IPC-2152
Standard for Determining
Current Carrying Capacity in
Printed Board Design
August 2009
A standard developed by IPC
Association Connecting Electronics Industries
®
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IPC-2152
®
Standard for Determining
Current Carrying Capacity
in Printed Board Design
Developed by the Current Carrying Capacity Task Group (1-10b) of the
Printed Board Design Committee (1-10) of IPC
Users of this standard are encouraged to participate in the
development of future revisions.
Contact:
IPC
3000 Lakeside Drive, Suite 309S
Bannockburn, Illinois
60015-1249
Tel 847 615.7100
Fax 847 615.7105
This Page Intentionally Left Blank
August 2009
IPC-2152
Acknowledgment
Any document involving a complex technology draws material from a vast number of sources. While the principal members
of the Current Carrying Capacity Task Group (1-10b) of the Printed Board Design Committee (1-10) are shown below, it is
not possible to include all of those who assisted in the evolution of this standard. To each of them, the members of the IPC
extend their gratitude.
Printed Board
Design Committee
Current Carrying
Capacity Task Group
Technical Liaisons of the
IPC Board of Directors
Chair
Lionel Fullwood
WKK Distribution Ltd.
Chair
Michael Jouppi
Lockheed Martin
Peter Bigelow
IMI Inc.
Vice Chair
Gary Ferrari
FTG Circuits
Sammy Yi
Aptina Imaging Corporation
Current Carrying Capacity Task Group
Byron Case, L-3 Communications
Phillip Chen, L-3 Communications
Electronic Systems
David Corbett, Defense Supply
Center Columbus
William Dieffenbacher, BAE Systems
Platform Solutions
C. Don Dupriest, Lockheed Martin
Missiles and Fire Control
Gary Ferrari, FTG Circuits
Lionel Fullwood, WKK Distribution
Ltd.
Michael Green, Lockheed Martin
Space Systems Company
Christopher Katzko, Shanghai
Meadville Electronics Co. Ltd.
Donald Kyle, Schlumberger Well
Services
Jim Long, ITT Power Solutions
Kenneth Manning, Raytheon
Company
Michael Miller, NSWC Crane
Tim Minko, Coretec Inc.
Gary Morgan, Ball Aerospace &
Technologies
Jack Olson, Caterpillar Inc.
William Ortloff, Raytheon Company
Karl Sauter, Sun Microsystems Inc.
Dewey Whittaker, Honeywell Inc. Air
Transport Systems
John Williams, Raytheon Company
A special note of thanks goes to the following individuals for their dedication to bringing this project to fruition.
We would like to highlight those individuals who made major contributions to the development of this standard.
C. Don Dupriest, Lockheed Martin
Missiles and Fire Control
Michael Green, Lockheed Martin
Space Systems Company
Michael Jouppi, Lockheed Martin
Jack Olson, Caterpillar Inc.
Michael Miller, NSWC Crane
Brian Strandjord, Thermal
Management, Inc.
iii
IPC-2152
August 2009
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August 2009
IPC-2152
Table of Contents
SCOPE ........................................................................ 1
A.3.3
Parallel Conductors............................................ 20
1.1
1.2
Purpose ................................................................ 1
Presentation ......................................................... 1
A.3.4
Vias..................................................................... 26
1.3
1.4
1.4.1
1.4.2
1.4.3
1.4.4
Interpretation ....................................................... 1
Definition of Terms ............................................ 1
Ambient .............................................................. 1
Base Material ...................................................... 1
Circuitry Layer ................................................... 1
Conductive Pattern ............................................. 1
A.3.4.2 Microvia ............................................................. 26
1.4.5
1.4.6
1
A.3.4.1 Conductor to Via to Plane ................................. 26
A.4
SUPPLEMENTAL MATERIAL ............................... 27
A.4.1
Flex Circuits....................................................... 27
A.4.2
PB Thickness ..................................................... 27
A.4.3
Copper Weight ................................................... 28
Conductor Spacing ............................................. 1
Conductor Thickness .......................................... 1
A.4.4
Board Material ................................................... 29
A.4.5
Environments ..................................................... 29
1.4.7
1.4.8
1.4.9
1.4.10
1.4.11
Conductor Width ................................................ 1
Convection .......................................................... 1
Copper Weight .................................................... 1
Current-Carrying Capacity ................................. 1
Heat Sink Plane .................................................. 2
A.4.6
Copper Planes .................................................... 29
1.4.12
1.4.13
Thermal Conductivity ......................................... 2
Thermal Resistance ............................................ 2
A.5.1
Heat Transfer from a Conductor ....................... 31
A.5.2
Conductor Power Dissipation............................ 31
2
APPLICABLE DOCUMENTS ..................................... 2
2.1
IPC ...................................................................... 2
A.4.6.1 Single Plane ....................................................... 29
A.4.6.2 Conductor Distance from Plane ........................ 30
A.5
ADDITIONAL TOPICS ........................................... 31
A.5.2.1 Conductor Electrical Resistance........................ 31
A.5.3
Odd Shaped Geometries and SwissCheese Effect ..................................................... 32
3
CONDUCTOR SIZING INTRODUCTION ................... 2
4
CONDUCTOR SIZING DESIGN GUIDELINES ......... 2
A.5.3.2 Voltage Sources.................................................. 32
5
CONDUCTOR SIZING CHARTS ............................... 3
A.5.3.3 Current Source (or Sink) ................................... 32
Conductor Sizing Charts for Still Air
Environments ...................................................... 6
Still Air Environment Charts in Imperial
(Inch) Units ......................................................... 6
Still Air Environment Charts in SI
(Metric) Units ..................................................... 9
Conductor Sizing Charts for Vacuum/Space
Environments .................................................... 12
A.5.3.4 Electrical Conductivity ...................................... 32
5.1
5.1.1
5.1.2
5.2
A.5.3.1 Voltage Drop Analysis ....................................... 32
A.5.4
HDI..................................................................... 33
A.5.5
High-Speed......................................................... 33
A.6 CONDUCTOR SIZING CHARTS ............................ 33
A.6.1
Conductor Sizing Charts for Still Air
Environments ..................................................... 33
5.2.1
Vacuum/Space Environment Charts in
Imperial (Inch) Units ........................................ 12
A.6.1.1 Still Air Environment Charts in Imperial
(Inch) Units ........................................................ 34
5.2.2
Vacuum/Space Environment Charts in SI
(Metric) Units ................................................... 15
A.6.1.2 Still Air Environment Charts in SI
(Metric) Units .................................................... 50
APPENDIX A
.............................................................. 18
A.1
INTRODUCTION ..................................................... 18
A.2
DERATING .............................................................. 18
A.3
SELECTING A CHART .......................................... 18
A.6.2
A.6.2.1 Vacuum/Space Environment Charts in
Imperial (Inch) Units ......................................... 68
A.6.2.2 Vacuum/Space Environment Charts in SI
(Metric) Units .................................................... 76
A.3.1
Conductor Temperature Rise ............................. 20
A.7
A.3.2
How to Use the Charts ...................................... 20
A.7.1
A.3.2.1 Chart Basics: Known Current ........................... 20
Conductor Sizing Charts for Vacuum/Space
Environments ..................................................... 68
REFERENCES ....................................................... 85
The Origin of the First Conductor
Sizing Chart ....................................................... 85
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IPC-2152
August 2009
Figures
Figure 5-1
Internal and External Conductors (All
Environments) ................................................... 5
Figure 5-2
Internal and External Conductors (Still Air)
(5-700 Sq-mils) ................................................. 6
Figure 5-3
Internal and External Conductors (Still Air)
(5-700 Sq-mils) ................................................. 7
Figure A-10
Two 2.03 mm [0.080 in] Conductors
(25.4 mm [1.0 in] spacing) No amperage
adjustment ...................................................... 26
Figure A-11
Via Cross-sectional Area ................................ 27
Figure A-12
Via Temperature Gradient .............................. 27
Figure A-13
Distance from Conductor to Copper Plane .... 30
Figure A-14
Single Conductor in a PB ............................... 31
Figure A-15
3 oz. External Conductors (Still Air) Log
(5 - 700 Sq-mils) ............................................. 34
Figure A-16
3 oz. External Conductors (Still Air)
(5 - 700 Sq-mils) ............................................. 35
Figure A-17
3 oz. External Conductors (Still Air)
(5 - 100 Sq-mils) ............................................. 35
Figure A-18
3 oz. External Conductors (Still Air)
(5 - 50 Sq-mils) ............................................... 36
Figure A-19
3 oz. Internal Conductors (Still Air) Log
(5 - 700 Sq-mils) ............................................. 37
Figure A-20
3 oz. Internal Conductors (Still Air)
(5 - 700 Sq-mils) ............................................. 38
Figure 5-4
Internal and External Conductors (Still Air)
(5-100 Sq-mils) ................................................. 7
Figure 5-5
Internal and External Conductors (Still Air)
(5 - 50 Sq-mils) ................................................. 8
Figure 5-6
Internal and External Conductors (Still Air)
(0.001 - 0.5 Sq-mm) ......................................... 9
Figure 5-7
Internal and External Conductors (Still Air)
(0.001 - 0.5 Sq-mm) ....................................... 10
Figure 5-8
Internal and External Conductors (Still Air)
(0.001 - 0.1 Sq-mm) ....................................... 10
Figure 5-9
Internal and External Conductors (Still Air)
(0.001 - 0.03 Sq-mm) ..................................... 11
Figure A-21
Figure 5-10
Internal and External Conductors (Vacuum)
(5 - 700 Sq-mils) ............................................. 12
3 oz. Internal Conductors (Still Air)
(5 - 100 Sq-mils) ............................................. 38
Figure A-22
Figure 5-11
Internal and External Conductors (Vacuum)
(5 - 700 Sq-mils) ............................................. 13
3 oz. Internal Conductors (Still Air)
(5 - 50 Sq-mils) ............................................... 39
Figure A-23
Figure 5-12
Internal and External Conductors (Vacuum)
(5 - 100 Sq-mils) ............................................. 13
2 oz. External Conductors (Still Air) Log
(5 - 700 Sq-mils) ............................................. 40
Figure A-24
Figure 5-13
Internal and External Conductors (Vacuum)
(5 - 50 Sq-mils) ............................................... 14
2 oz. External Conductors (Still Air)
(5 - 700 Sq-mils) ............................................. 41
Figure A-25
Figure 5-14
Internal and External Conductors (Vacuum)
(0.001 - 0.5 Sq-mm) ....................................... 15
2 oz. External Conductors (Still Air)
(5 - 100 Sq-mils) ............................................. 41
Figure A-26
Figure 5-15
Internal and External Conductors (Vacuum)
(0.001 - 0.5 Sq-mm) ....................................... 16
2 oz. External Conductors (Still Air)
(5 - 50 Sq-mils) ............................................... 42
Figure A-27
Figure 5-16
Internal and External Conductors (Vacuum)
(0.001 - 0.1 Sq-mm) ....................................... 16
2 oz. Internal Conductors (Still Air) Log
(5 - 700 Sq-mils) ............................................. 43
Figure A-28
Figure 5-17
Internal and External Conductors (Vacuum)
(0.001 - 0.03 Sq-mm) ..................................... 17
2 oz. Internal Conductors (Still Air)
(5 - 700 Sq-mils) ............................................. 44
Figure A-29
Figure A-1
External and Internal Conductors
(This figure is a duplicate of Figure 5-1
in IPC-2152) ................................................... 19
2 oz. Internal Conductors (Still Air)
(5 - 100 Sq-mils) ............................................. 44
Figure A-30
2 oz. Internal Conductors (Still Air)
(5 - 50 Sq-mils) ............................................... 45
Figure A-2
External and Internal Conductor Sizing
Chart ............................................................... 21
Figure A-31
1 oz. Internal Conductors (Still Air) Log
(5 - 700 Sq-mils) ............................................. 46
Figure A-3
Parallel Conductors ........................................ 22
Figure A-32
Figure A-4
[0.010 in] wide (1-oz.) Conductor at 10 °C
Temperature Gradient ..................................... 23
1 oz. Internal Conductors (Still Air)
(5 - 700 Sq-mils) ............................................. 46
Figure A-33
1 oz. Internal Conductors (Still Air)
(5 - 100 Sq-mils) ............................................. 47
Figure A-34
1 oz. Internal Conductors (Still Air)
(5 - 50 Sq-mils) ............................................... 47
Figure A-35
1⁄2 oz. Internal Conductors (Still Air)
Log (5 - 700 Sq-mils) ..................................... 48
Figure A-36
1⁄2 oz. Internal Conductors (Still Air)
(5 - 700 Sq-mils) ............................................. 48
Figure A-37
1⁄2 oz. Internal Conductors (Still Air)
(5 - 100 Sq-mils) ............................................. 49
Figure A-38
1⁄2 oz. Internal Conductors (Still Air)
(5 - 50 Sq-mils) ............................................... 49
Figure A-39
3 oz. External Conductors (Still Air) Log
(0.001 - 0.5 Sq-mm) ....................................... 50
Figure A-5
4.06 mm [0.160 in] Single Conductor ............ 23
Figure A-6
Two 2.03 mm [0.080 in] conductors
(2.54 mm [0.100 in] spacing) amperage
adjusted for parallel conductor ....................... 24
Figure A-7
Two 2.03 mm [0.080 in] Conductors
(2.54 mm [0.100 in] spacing) No
amperage adjustment ..................................... 24
Figure A-8
Two 2.03 mm [0.080 in] Conductors
(12.7 mm [0.50 in] spacing) Amperage
adjusted for Parallel Conductor ...................... 25
Figure A-9
Two 2.03 mm [0.080 in] Conductors
(25.4 mm [1.0 in] spacing) Amperage
adjusted for Parallel Conductor ...................... 25
vi
August 2009
IPC-2152
Figure A-40
3 oz. External Conductors (Still Air)
(0 - 0.5 Sq-mm) .............................................. 51
Figure A-68
2 oz. Conductors (Vacuum)
(5 - 700 Sq-mils) ............................................. 72
Figure A-41
3 oz. External Conductors (Still Air)
(0 - 0.1 Sq-mm) .............................................. 51
Figure A-69
2 oz. Conductors (Vacuum)
(5 - 100 Sq-mils) ............................................. 72
Figure A-42
3 oz. External Conductors (Still Air)
(0 - 0.03 Sq-mm) ............................................ 52
Figure A-70
2 oz. Conductors (Vacuum)
(5 - 50 Sq-mils) ............................................... 73
Figure A-43
3 oz. Internal Conductors (Still Air) Log
(0 - 700 Sq-mm) ............................................. 53
Figure A-71
1⁄2 oz. Conductors (Vacuum) Log
(5 - 700 Sq-mils) ............................................. 74
Figure A-44
3 oz. Internal Conductors (Still Air)
(0 - 0.5 Sq-mm) .............................................. 54
Figure A-72
1⁄2 oz. Conductors (Vacuum)
(5 - 700 Sq-mils) ............................................. 74
Figure A-45
3 oz. Internal Conductors (Still Air)
(0 - 0.1 Sq-mm) .............................................. 54
Figure A-73
1⁄2 oz. Conductors (Vacuum)
(5 - 100 Sq-mils) ............................................. 75
Figure A-46
3 oz. Internal Conductors (Still Air)
(0 - 0.03 Sq-mm) ............................................ 55
Figure A-74
1⁄2 oz. Conductors
(5 - 50 Sq-mils) ............................................... 75
Figure A-47
2 oz. External Conductors (Still Air) Log
(0.001 - 0.5 Sq-mm) ....................................... 56
Figure A-75
3 oz. Conductors (Vacuum) Log
(0.001 - 0.5 Sq-mm) ....................................... 76
Figure A-48
2 oz. External Conductors (Still Air)
(0.001 - 0.5 Sq-mm) ....................................... 57
Figure A-76
3 oz. Conductors (Vacuum)
(0 - 0.5 Sq-mm) .............................................. 77
Figure A-49
2 oz. External Conductors (Still Air)
(0 - 0.1 Sq-mm) .............................................. 57
Figure A-77
3 oz. Conductors (Vacuum)
(0 - 0.1 Sq-mm) .............................................. 77
Figure A-50
2 oz. External Conductors (Still Air)
(0 - 0.03 Sq-mm) ............................................ 58
Figure A-78
3 oz. Conductors (Vacuum)
(0 - 0.03 Sq-mm) ............................................ 78
Figure A-51
2 oz. Internal Conductors (Still Air) Log
(0 - 0.5 Sq-mm) .............................................. 59
Figure A-79
2 oz. Conductors (Vacuum) Log
(0 - 0.5 Sq-mm) .............................................. 79
Figure A-52
2 oz. Internal Conductors (Still Air)
(0 - 0.5 Sq-mm) .............................................. 60
Figure A-80
2 oz. Conductors (Vacuum)
(0 - 0.5 Sq-mm) .............................................. 80
Figure A-53
2 oz. Internal Conductors (Still Air)
(0 - 0.1 Sq-mm) .............................................. 60
Figure A-81
2 oz. Conductors (Vacuum)
(0 - 0.1 Sq-mm) .............................................. 80
Figure A-54
2 oz. Internal Conductors (Still Air)
(0 - 0.03 Sq-mm) ............................................ 61
Figure A-82
2 oz. Conductors (Vacuum)
(0 - 0.03 Sq-mm) ............................................ 81
Figure A-55
1 oz. Internal Conductors (Still Air) Log
(0 - 0.1 Sq-mm) .............................................. 62
Figure A-83
1⁄2 oz. Conductors (Vacuum) Log
(0 - 0.5 Sq-mm) .............................................. 82
Figure A-56
1 oz. Internal Conductors (Still Air)
(0 - 0.5 Sq-mm) .............................................. 62
Figure A-84
1⁄2 oz. Conductors (Vacuum)
(0 - 0.5 Sq-mm) .............................................. 82
Figure A-57
1 oz. Internal Conductors (Still Air)
(0 - 0.1 Sq-mm) .............................................. 63
Figure A-85
1⁄2 oz. Conductors (Vacuum)
(0 - 0.1 Sq-mm) .............................................. 83
Figure A-58
1 oz. Internal Conductors (Still Air)
(0 - 0.03 Sq-mm) ............................................ 64
Figure A-86
1⁄2 oz. Conductors (Vacuum)
(0 - 0.03 Sq-mm) ............................................ 83
Figure A-59
1⁄2 oz. Internal Conductors (Still Air)
Log (0 - 0.5 Sq-mm) ....................................... 65
Figure A-87
Log width chart ............................................... 84
Figure A-88
Log width chart (inch) ..................................... 84
Figure A-60
1⁄2 oz. Internal Conductors (Still Air)
(0 - 0.5 Sq-mm) .............................................. 65
Figure A-89
Original NBS Chart ......................................... 86
Figure A-61
1⁄2 oz. Internal Conductors (Still Air)
(0 - 0.1 Sq-mm) .............................................. 66
Figure A-90
NBS 10 °C Data Curves ................................. 87
Figure A-91
Historical IPC Charts ...................................... 88
Figure A-62
1⁄2 oz. Internal Conductors (Still Air)
(0 - 0.03 Sq-mm) ............................................ 67
Figure A-63
3 oz. Conductors (Vacuum) Log
(5 - 700 Sq-mils) ............................................. 68
Table A-1
Minimum Internal Copper Foil Thickness
(For Reference Only) ........................................ 28
Figure A-64
3 oz. Conductors (Vacuum)
(0 - 700 Sq-mils) ............................................. 69
Table A-2
Minimum External Conductor Thickness
(For Reference Only) ........................................ 28
Figure A-65
3 oz. Conductors (Vacuum)
(0 - 100 Sq-mils) ............................................. 69
Table A-3
Material Thermal Conductivity .......................... 29
Table A-4
Skin Depth Parameters ..................................... 33
Figure A-66
3 oz. Conductors (Vacuum)
(5 - 50 Sq-mils) ............................................... 70
Table A-5
NBS Data Reference Table ............................... 89
Figure A-67
2 oz. Conductors (Vacuum) Log
(5 - 700 Sq-mils) ............................................. 71
Table A-6
NBS Data Reference Table (Cont’d) ................. 89
Table A-7
NBS Data Reference Table (Cont’d) ................. 89
Tables
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IPC-2152
Standard for Determining Current Carrying
Capacity in Printed Board Design
1 SCOPE
This document is intended as a general guide to understanding the relationship between current, conductor size, and temperature, and can be used more specifically in the design and evaluation of copper conductors in printed boards (PBs).
1.1 Purpose The purpose of this document is to provide guidance on determining the appropriate conductor sizes on the
finished PB as a function of the current carrying capacity required and the acceptable conductor temperature rise.
1.2 Presentation All dimensions and tolerances in this standard are expressed in hard SI (metric) units and parenthetical
soft imperial (inch) units. Users of this standard are expected to use metric dimensions.
1.3 Interpretation ‘‘Shall,‘‘ the imperative form of the verb, is used throughout this standard whenever a requirement is
intended to express a provision that is mandatory. Deviation from a ‘‘shall‘‘ requirement may be considered if sufficient data
is supplied to justify the exception.
The words ‘‘should’’ and ‘‘may’’ are used whenever it is necessary to express non-mandatory provisions.
‘‘Will’’ is used to express a declaration of purpose.
To assist the reader, the word ‘‘shall‘‘ is presented in bold characters.
1.4 Definition of Terms
The definition of all terms used herein shall be in accordance with IPC-T-50 and as defined in
1.4.1 through 1.4.13.
1.4.1 Ambient
The surrounding environment coming into contact with the system or component in question.
1.4.2 Base Material The insulating material upon which a conductive pattern may be formed (The base material may be
rigid or flexible or both. It may be a dielectric or insulated metal sheet).
1.4.3 Circuitry Layer
A layer of PB containing conductors, including ground and voltage planes.
1.4.4 Conductive Pattern The configuration or design of the conductive material on a base material. (This includes conductors, lands, vias, planes, and passive components when these are an integral part of the PB manufacturing process.)
1.4.5 Conductor Spacing The observable distance between adjacent edges (not center-to-center spacing) of isolated conductive patterns in a conductor layer.
1.4.6 Conductor Thickness
Thickness of a conductor including additional metallic coatings but excluding non-conductive
coatings.
1.4.7 Conductor Width The observable width of a conductor at any point chosen at random on a PB as viewed from
directly above unless otherwise specified.
1.4.8 Convection
Heat transfer that occurs at the interface of a solid and a fluid or gas that is due to their differences in
temperature.
1.4.9 Copper Weight The mass of copper per unit area for a foil, typically expressed in ounces per square foot or grams
per square centimeter (these units are not equivalent).
The maximum electrical current that can be carried continuously by a conductor, without causing an objectionable degradation of electrical or mechanical properties of the product.
1.4.10 Current-Carrying Capacity
1
IPC-2152
August 2009
1.4.11 Heat Sink Plane
A continuous sheet of metal on or in a PB that functions to dissipate heat away from heat gener-
ating components.
1.4.12 Thermal Conductivity The property of a material that describes the rate at which heat will be conducted through
a unit area of the material for a given driving force.
1.4.13 Thermal Resistance
The resistance of a material to the passage of thermal energy, usually measured in degrees
°C/W.
2 APPLICABLE DOCUMENTS
The following documents, of the issue currently in effect, form a part of this document to the extent specified herein.
2.1 IPC1
IPC-T-50
Terms and Definitions for Interconnecting and Packaging Electronic Circuits
IPC-A-600
Acceptability of Printed Boards
IPC-2221
Generic Standard on Printed Board Design
IPC-6012
Qualification and Performance Specification for Rigid Printed Boards
IPC-TM-650
Test Methods Manual2
2.5.4.1 Conductor Temperature Rise Due to Current Changes in Conductors
3 CONDUCTOR SIZING INTRODUCTION
A PB consists of one or more layers of conductive material (usually copper) separated or supported by layers of insulating
base material. When a circuit is energized, current flowing through the conductors generates heat, which creates a temperature rise in the conductor and the surrounding area. The conductor temperature rise, also referred to as delta T (ΔT), is the
conductor temperature compared to the local PB temperature.
When current is applied to a conductor, its temperature rise is dependent upon its cross sectional area and factors such as
the PB thickness, PB material, amount and adjacency of copper in the PB, and the environment in which the PB is being
operated. The mounting of the PB, environment (air, vacuum, forced air), copper plane layers, the components that the conductor is connected to, and length of the conductor are a partial list of the things that can impact the conductor temperature
rise. It is not feasible to assemble charts that address all of these concerns. Therefore, charts are presented that take into
account a wide spectrum of design concerns that bound most PB designs used in still air and vacuum environments.
The conductor temperature rise, calculated using the charts in this document and in Appendix A, is one contribution to the
overall temperature rise of the electronics system. Components on the PB will contribute to the PB temperature rise. Many
other contributions to the PB temperature rise may occur in a particular application. When considering the ambient temperature, with respect to the charts in this document, one must evaluate all the contributions to the overall temperature rise of
the PB in the worst case use conditions in which it is required to operate.
4 CONDUCTOR SIZING DESIGN GUIDELINES
The following guidelines may be used for determining conductor width, conductor thickness, cross-sectional area, and
current-carrying capacity with respect to temperature rise.
a) For the conductor being evaluated, it is assumed that the conductor surface area is relatively small compared to the adjacent free PB area and that the PB area is 76.2 x 76.2 mm [3.0 x 3.0 in] or greater. Reducing the PB size, as well as the
PB thickness, increases the conductor temperature rise.
Note: The reference PB size is 366 x 142 x 1.79 mm [14.4 x 5.6 x 0.07 in].
b) It is assumed that the PB thickness is between 1.52 mm [0.06 in] and 1.79 mm [0.07 in]. PBs less than 1.52 mm [0.06
in] in thickness will have a higher temperature rise than those represented by the charts in 5.1 and 5.2. Reducing the PB
1. www.ipc.org
2. Current and revised IPC Test Methods are available on the IPC Web site (www.ipc.org/html/testmethods.htm)
2
August 2009
IPC-2152
thickness from 1.79 to 1.02 mm [0.07 to 0.04 in] results in an increase in the ΔT by an approximate factor of 1.4. See
A.4.2 of Appendix A for further discussions regarding the effect of temperature rise and PB thickness.
c) The curves in Section 5 are not derated; they represent the temperature rise of a single conductor in a PB, as described
in Section 3. When estimating the conductor cross-sectional area, consideration should be given to allow for material
and process variations, such as undercut and final copper thickness. To account for process variations, a smaller crosssectional area should be used. See IPC-2221 or IPC-A-600 for discussion on etched conductor characteristics.
The thickness of copper after processing has a minimum allowable value (see IPC-6012 or procurement documentation).
d) As far as other design constraints allow, conductors should be sized to keep the temperature rise to a minimum. The conductor temperature rise, otherwise referred to as the ΔT, will be the temperature rise above the local PB temperature surrounding the conductor. Components and other conditions will drive the PB to temperatures above the surrounding environmental temperature. For example, if the PB is at 75 °C during operation and the conductor is sized for a 10 °C rise,
then the conductor temperature will be 85 °C.
NOTE: The increase in electrical resistance of the conductor due to an elevated temperature is a secondary effect on
conductor temperature rise. See A.5.2.1 of Appendix A for an example that shows the change in resistance of a conductor with respect to temperature rise.
e) For isolated conductor applications the charts in Section 5 may be used directly. For groups of parallel conductors, if
closely spaced, the temperature rise may be found by using an equivalent cross-section and an equivalent current. The
following apply to parallel conductors:
1) Parallel conductors refer to adjacent conductors on the same layer and on adjacent layers.
2) Adjacent conductors within 25.4 mm [1.0 in] can affect the temperature rise. This means that, for many PBs, all conductors are thermally linked and need to be considered as such.
3) The equivalent cross-section is equal to the sum of the cross-sections of the parallel conductors.
4) The equivalent current is the sum of the currents in the conductors.
See A.3.3 of Appendix A for computer generated simulations that illustrate the temperature distribution around heated
conductors.
f) For conductors with cross-sectional areas greater than 452 mm2 [0.700 in2], extrapolating the charts in Section 5 is not
recommended without first performing a thermal analysis of the application.
5 CONDUCTOR SIZING CHARTS
Charts have been developed as estimation tools to predict the relationship between current, conductor size and temperature
rise. If more accurate predictions are needed than these charts are capable of providing, a thermal analysis based on the specific parameters of the design may be necessary.
The charts included in this document represent copper conductors in a polyimide or FR-4 epoxy resin based PB without
copper plane layers. This configuration is consistent with IPC-TM-650, Method 2.5.4.1. Variations from this baseline configuration are discussed in Section A.3 and A.4.4 of Appendix A. The charts presented in this document, for most cases, will
predict higher temperatures than the actual conductor will experience for a specific current level. A discussion is included
in section A.2 and A.4.6 of Appendix A on the topic of temperature margins that can exist using the charts.
Multiple charts are presented for each set of parameters for sizing electrical conductors. These charts are presented as an aid
to increase the level of precision when determining the temperature rise of a conductor or group of conductors. If a more
precise estimate of the conductor temperature rise is needed, see Appendix A for further information.
The universal chart in Figure 5-1 is recommended for sizing all conductors, both internal and external, in all environments,
subject to the guidelines provided in Section 4. Results from this chart are dependable but very conservative, resulting in
conductor sizes that may be greater than needed for many applications. The series of charts following 5-1 are provided for
when design constraints require a more accurate estimation.
The charts in 5.1 are recommended for sizing both internal and external conductors in air environments when smaller conductor sizes are needed than those sized using Figure 5-1.
The charts in 5.2 are recommended for both internal and external conductors in vacuum environments when smaller conductor sizes are needed than those sized using Figure 5-1.
Review A.7.1 of Appendix A for details regarding the origin of these charts and further discussion on conductor temperature rise from an applied current.
3
IPC-2152
August 2009
How to Use the Chart in Figure 5-1 The charts require knowing two of three variables: desired continuous current,
acceptable conductor temperature rise, or conductor cross-sectional area. If any two of these are known, the third can be
approximated.
For example, if a conductor must carry 5 amps with a maximum temperature rise of 10 °C, what is the appropriate conductor width?
On the lower chart in Figure 5-1, find the ‘‘5-amp’’ line on the vertical axis, and follow it across until it intersects the 10
°C curve. Follow the line at that intersection down to the axis to find the appropriate cross-sectional area of the conductor
(400 sq-mils).
Then, move to the upper chart in Figure 5-1, which shows the relationship between cross-sectional area and conductor width
and thickness. Assume the PB design is going to use 1 oz. copper layers. To find the appropriate conductor width, use the
same 400 sq-mil line and follow it to where it crosses the 1 oz. copper curve. Finally, follow the line intersecting the 1 oz.
copper curve back to the axis labeled ‘‘Conductor Width In Inches’’ to find that the conductor width should be 0.30 in. Work
in reverse to find the maximum current if the conductor width is known.
4
August 2009
IPC-2152
0
Conductor Width in Inches
.001
.005
.010
.015
.020
.030
.050
.070
(3 o
z/ft 2
).00
42"
(2
oz/ 2
ft )
.00
28"
.100
.150
.200
(1
2 oz
/ft 2
).0
.250
.300
.350
(1
00
oz
/ft 2
).0
7"
01
4"
.400
0
1
5
10
20 30
50
70
100
150
200
250 300
400
500
600
700
Cross-Sectional Area (Sq-mils)
Conductor width to cross-section relationship
17.5
15.0
C
45º
C
30º
12.5
Current in Amperes
10.0
20º
C
7.5
10ºC
6.0
5.0
4.0
3.5
3.0
2.5
2.0
1.5
1.0
.75
.50
.30
.25
.125
.062
0
0
1
5
10
20 30
50
70
100
150
200
250 300
400
500
600
700
Cross-Sectional Area (Sq-mils)
IPC-2152-5-1
Figure 5-1
Internal and External Conductors (All Environments)
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August 2009
5.1 Conductor Sizing Charts for Still Air Environments
5.1.1 Still Air Environment Charts in Imperial (Inch) Units Figure 5-2 through Figure 5-5 represent charts for internal and
external conductors in still air environments in imperial (inch) units.
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
5ºC
Current (Amps)
10
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-Sectional Area (Sq-mils)
1
10
100
1000
0.0001
Width (inch)
0.001
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1-oz (0.0013 in thick)
1
1/2-oz (0.00065 in thick)
1/4-oz (0.000325 in thick)
10
IPC-2152-5-2
Figure 5-2
6
Internal and External Conductors (Still Air) (5-700 Sq-mils)
August 2009
IPC-2152
30
100ºC
25
75ºC
60ºC
Current (Amps)
20
45ºC
15
30ºC
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
600
700
800
Cross-Sectional Area (Sq-mils)
IPC-2152-5-3
Figure 5-3
Internal and External Conductors (Still Air) (5-700 Sq-mils)
100ºC
75ºC
60ºC
45ºC
5
30ºC
4.5
4
20ºC
Current (Amps)
3.5
3
10ºC
2.5
2
5ºC
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Cross-Sectional Area (Sq-mils)
IPC-2152-5-4
Figure 5-4
Internal and External Conductors (Still Air) (5-100 Sq-mils)
7
IPC-2152
August 2009
100ºC
5
75ºC
4.5
60ºC
4
45ºC
3.5
Current (Amps)
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-5-5
Figure 5-5
8
Internal and External Conductors (Still Air) (5 - 50 Sq-mils)
August 2009
IPC-2152
5.1.2 Still Air Environment Charts in SI (Metric) Units Figure 5-6 through Figure 5-9 represent charts for internal and
external conductors in still air environments in SI (metric) units.
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
Current (Amps)
10
5ºC
2ºC
1ºC
1
0.1
0.001
0.01
0.1
1
Cross-sectional Area (Sq-mm)
0.001
0.01
0.1
1
0.01
Width (mm)
0.1
1
10
3-oz (0.099 mm thick)
2-oz (0.066 mm thick)
1-oz (0.033 mm thick)
1/2-oz (0.00165 mm thick)
1/4-oz (0.00826 mm thick)
100
IPC-2152-5-6
Figure 5-6
Internal and External Conductors (Still Air) (0.001 - 0.5 Sq-mm)
9
IPC-2152
August 2009
35
30
100ºC
25
75ºC
Current (Amps)
60ºC
20
45ºC
30ºC
15
20ºC
10
10ºC
5ºC
2ºC
1ºC
5
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-sectional Area (Sq-mm)
IPC-2152-5-7
Figure 5-7
Internal and External Conductors (Still Air) (0.001 - 0.5 Sq-mm)
100ºC
10
75ºC
9
60ºC
8
45ºC
Current (Amps)
7
30ºC
6
5
20ºC
4
10ºC
3
5ºC
2
2ºC
1ºC
1
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Cross-sectional Area (Sq-mm)
IPC-2152-5-8
Figure 5-8
10
Internal and External Conductors (Still Air) (0.001 - 0.1 Sq-mm)
August 2009
IPC-2152
100ºC
5
75ºC
4.5
60ºC
4
Current (Amps)
45ºC
3.5
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Cross-sectional Area (Sq-mm)
IPC-2152-5-9
Figure 5-9
Internal and External Conductors (Still Air) (0.001 - 0.03 Sq-mm)
11
IPC-2152
August 2009
5.2 Conductor Sizing Charts for Vacuum/Space Environments The following charts are for vacuum or space environments. They can also be considered as a conservative estimate for high altitude requirements.
5.2.1 Vacuum/Space Environment Charts in Imperial (Inch) Units Figure 5-10 through Figure 5-13 represent charts for
internal and external conductors in vacuum environments in imperial (inch) units.
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
5ºC
Current (Amps)
10
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-sectional Area (Sq-mils)
1
10
100
1000
0.0001
Width (inch)
0.001
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1-oz (0.0013 in thick)
1
1/2-oz (0.00065 in thick)
1/4-oz (0.000325 in thick)
10
IPC-2152-5-10
Figure 5-10
12
Internal and External Conductors (Vacuum) (5 - 700 Sq-mils)
August 2009
IPC-2152
30
Current (Amps)
25
100ºC
75ºC
20
60ºC
45ºC
15
30ºC
20ºC
10
10ºC
5
5ºC
2ºC
1ºC
0
0
100
200
300
400
500
600
700
800
Cross-Sectional Area (Sq-mils)
IPC-2152-5-11
Figure 5-11
Internal and External Conductors (Vacuum) (5 - 700 Sq-mils)
100ºC
75ºC
60ºC
45ºC
5
4.5
30ºC
4
Current (Amps)
3.5
20ºC
3
2.5
10ºC
2
5ºC
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Cross-Sectional Area (Sq-mils)
IPC-2152-5-12
Figure 5-12
Internal and External Conductors (Vacuum) (5 - 100 Sq-mils)
13
IPC-2152
August 2009
100ºC
Current (Amps)
5
4.5
75ºC
4
60ºC
3.5
45ºC
3
30ºC
2.5
20ºC
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-5-13
Figure 5-13
14
Internal and External Conductors (Vacuum) (5 - 50 Sq-mils)
August 2009
IPC-2152
5.2.2 Vacuum/Space Environment Charts in SI (Metric) Units Figure 5-14 through Figure 5-17 represent charts for internal and external conductors in vacuum environments in SI (metric) units.
100
20ºC
10ºC
5ºC
5ºC
1ºC
Current (Amps)
10
100ºC
75ºC
60ºC
45ºC
30ºC
1
0.1
0.01
0.001
0.01
0.1
1
Cross-sectional Area (Sq-mm)
0.001
0.01
0.01
0.1
1
Width (mm)
0.1
1
10
3-oz (0.099 mm thick)
2-oz (0.066 mm thick)
1-oz (0.033 mm thick)
1/2-oz (0.0165 mm thick)
1/4-oz (0.00826 mm thick)
100
IPC-2152-5-14
Figure 5-14
Internal and External Conductors (Vacuum) (0.001 - 0.5 Sq-mm)
15
IPC-2152
August 2009
30
100ºC
25
Current (Amps)
75ºC
20
60ºC
45ºC
15
30ºC
20ºC
10
10ºC
5
5ºC
2ºC
1ºC
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
IPC-2152-5-15
Figure 5-15
Internal and External Conductors (Vacuum) (0.001 - 0.5 Sq-mm)
100ºC
10
9
75ºC
8
60ºC
Current (Amps)
7
45ºC
6
30ºC
5
20ºC
4
3
10ºC
2
5ºC
1
2ºC
1ºC
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Cross-Sectional Area (Sq-mm)
IPC-2152-5-16
Figure 5-16
16
Internal and External Conductors (Vacuum) (0.001 - 0.1 Sq-mm)
August 2009
IPC-2152
100ºC
5
Current (Amps)
4.5
75ºC
4
60ºC
3.5
45ºC
3
30ºC
2.5
20ºC
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Cross-Sectional Area (Sq-mm)
IPC-2152-5-17
Figure 5-17 Internal and External Conductors (Vacuum) (0.001 - 0.03 Sq-mm)
17
IPC-2152
August 2009
APPENDIX A
A.1 INTRODUCTION
This appendix is included as a resource for topics concerning conductor temperature rise and determining current carrying
capacity in printed board (PB) conductors.
PBs can be extremely different from one design to another. They can vary from a double-sided PB the size of a postage
stamp to a forty layer PB that is two feet wide, four feet long and a half-inch thick. The environment in which the PB must
operate is also a consideration, whether it is used on Earth, at sea-level or 18,288 m [60,000 ft], immersed in a fluid, operating in space (vacuum), or on some other planet.
With such a broad range of PB construction, materials, and operating environments, a single conductor-sizing chart cannot
be expected to describe the temperature rise of a conductor as a function of current for all PB designs. Fine line and space,
heavy copper, single-layer PBs and multilayer PBs all constitute different configurations in which conductors with the same
cross-sectional area vary from 10 to 100 °C or more for the same amount of applied current.
If the designer is coming to this appendix as a means of reducing conductor size and/or determining temperature margin,
then a new set of criteria needs to be considered. The criteria are PB thickness, copper thickness, number of copper plane
layers and the distance from the conductor to each adjacent copper plane layer.
The charts in IPC-2152, with the exception of Figure 5-1 (which is duplicated in this Appendix as Figure A-1), are developed from 1.79 mm [0.070 in] thick, polyimide PB test vehicles. This appendix discusses how PB thickness, copper thickness vs. cross-sectional area, copper plane layers, and the distance from a conductor to a copper plane layer affect the temperature rise of a PB conductor.
Information in this appendix was developed from current carrying capacity testing using polyimide and FR-4 PB test
vehicles with no internal copper planes. Test vehicles and testing were performed following IPC-TM-650, Method 2.5.4.1.
Data from 1.79 mm [0.070 in] thick polyimide PB test vehicles are presented in the form of charts. Although data was also
collected for FR-4 boards with thicknesses of 0.965 mm [0.038 in] and 1.50 mm [0.059 in], only the polyimide data is presented. The FR-4 data sets are used for comparison and to discuss the effect of the PB thickness and material thermal conductivity with respect to the charts in IPC-2152.
A.2 DERATING
Conductors that are sized using IPC-2152 have no specific derating applied to them. In most cases, conductors will operate
at a temperature rise less than estimated using the charts in this document. In the general case of a PB that has one or more
copper planes in the PB, the conductors will have a lower temperature rise than estimated using the conductor sizing charts.
Conductor temperature rise margins based on the presence of copper plane layers in a PB design can be estimated using
guidelines in A.4.6.
Internal and external conductors operate very close to the same temperature rise for the same applied current and crosssectional area. Conductors in a vacuum environment operate at higher temperatures than in air for the same size conductor
and applied current.
A.3 SELECTING A CHART
A chart is selected by knowing the desired conductor thickness and the environment in which it will operate, such as in air
or vacuum.
Considerations before selecting a chart include:
a)
PB Material: If the PB material is not polyimide or FR-4, and if the material has a lower thermal conductivity than the
values listed in Table A-3, it is recommended to only use Figure A-1 for sizing conductors.
b) PB Thickness: If the PB thickness is less than 1.79 mm [0.070 in], see A.4.2.
c)
Conductor Thickness: Increasing the width of a conductor by using a thinner copper layer for a desired conductor
cross-sectional area will lower the temperature rise of a conductor. (See the charts for the differences.)
Figure A-1 is the most conservative of all conductor-sizing charts, taking into consideration both internal and external conductors, the PB material, board thickness, and environmental conditions such as air or vacuum. Presented in A.7.1 is a full
discussion of the chart in Figure A-1. Conservative, in this case, is when the actual temperature rise of a conductor is lower
than that estimated by the chart.
18
August 2009
IPC-2152
0
Conductor Width in Inches
.001
.005
.010
.015
.020
.030
.050
.070
(3 o
z/ft 2
).00
42"
(2
oz/ 2
ft )
.00
28"
.100
.150
.200
(1
2 oz
/ft 2
).0
.250
.300
.350
(1
00
oz
/ft 2
).0
7"
01
4"
.400
0
1
5
10
20 30
50
70
100
150
200
250 300
400
500
600
700
Cross-Sectional Area (Sq-mils)
Conductor width to cross-section relationship
17.5
15.0
C
45º
C
30º
12.5
Current in Amperes
10.0
20º
C
7.5
10ºC
6.0
5.0
4.0
3.5
3.0
2.5
2.0
1.5
1.0
.75
.50
.30
.25
.125
.062
0
0
1
5
10
20 30
50
70
100
150
200
250 300
400
500
600
700
Cross-Sectional Area (Sq-mils)
IPC-2152-a-1
Figure A-1
External and Internal Conductors (This figure is a duplicate of Figure 5-1 in IPC-2152)
19
IPC-2152
August 2009
Figure A-15 through Figure A-89 represent test data collected using test vehicles made from polyimide PB material. The
charts are organized with respect to copper thickness, external conductors (air) in imperial (inch) units, external conductors
(air) in SI (metric) units, internal conductors (air) in imperial (inch) units, internal conductors (air) in SI (metric) units and
then charts following the same outline for vacuum environments.
A.3.1 Conductor Temperature Rise The conductor temperature rise derived from a chart represents the increase in the
conductor temperature above the local PB temperature surrounding the conductor. Knowing the continuous current that is
applied to a specific size conductor and using the most appropriate chart, an estimate of the conductor temperature rise can
be made. The cross-sectional area is defined by the width and thickness of the conductor.
The temperature rise as mentioned above is the increase in conductor temperature above the local PB temperature when current is applied. For example, if the PB operates at 85 °C and the conductor is designed for a 10 °C rise, then the conductor
will be 95 °C. A 10 °C rise is a common temperature rise for a design. The temperature rise should always be minimized.
Increasing the size of a conductor will lower the temperature rise, lower the power being dissipated in the PB, lower the
voltage drop across the conductor, decrease component temperatures and improve the reliability of the product. It is important to always consider the component temperature for its worst-case environment to determine the allowable conductor
temperature rise.
The designer must know the PB temperature during the worst case operating conditions. The PB temperature must take into
consideration the power dissipation from the components, conductors, connectors, mounting configuration and environment
that it must operate.
A.3.2 How to Use the Charts Conductor sizing charts require knowing two of three variables: current, conductor temperature rise, or conductor cross-sectional area. Knowing any two of the three variables will allow the other to be determined.
A.3.2.1 Chart Basics: Known Current When the current and the desired temperature rise are known, then the conductor
width can be calculated for various conductor thicknesses.
Example 1: What is the recommended size conductor for a 10 °C rise when 1 Amp is applied to it?
Starting with the upper chart in Figure A-2, follow the line going across from 1 Amp to the curve labeled 10 °C. The 10
°C curve represents the temperature rise that will occur for a specific size conductor at a specific current level. Next, follow the line going down from the 10 °C curve and look at where it intersects the axis labeled ‘‘Cross-Sectional Area
Sq-mils’’. The cross section is the cross-sectional area of the conductor. The final step is to determine the conductor width.
The lower chart in Figure A-2 is used to determine the conductor width for various copper thicknesses. For the same crosssectional area, the width will be smaller for thick copper and wider for thinner copper. Continuing with the example, follow the vertical line down from 50 sq-mils into the lower chart to the line labeled ‘‘1 oz. (0.0013’’ thick). Following the line
across to the axis labeled ‘‘Width (inch)’’ it shows the conductor should be approximately 0.040 in. wide for a copper conductor that is 0.0013 in. thick. If 3 oz. copper was selected, the conductor width would be approximately 0.015 in wide,
rather than 0.040 in wide for 1 oz. copper.
A.3.3 Parallel Conductors Parallel conductors refer to conductors on the same layer as shown in Figure A-3, as well as
conductors on adjacent layers. The concept of parallel conductors and how to calculate the cross-sectional area of a group
of parallel conductors is critical to properly sizing PB conductors. The method for sizing parallel conductors from the design
guidelines is described below.
For groups of closely spaced parallel conductors, the temperature rise may be found by using an equivalent cross-section
and an equivalent current. (Closely spaced is on the order of 25.4 mm [1.0 in] spacing and less.) The equivalent cross-section
is equal to the sum of the cross-section of the parallel conductors, and the equivalent current is the sum of the current in
each of the parallel conductors.
Example 2: Determine the maximum current in a 0.03 mm [0.0011 in] wide conductor, 1⁄4-oz. copper (0.00035 in thick),
with a maximum temperature rise of 10 °C; if there are 16 conductors in parallel.
a) Cross-sectional area of one conductor = 0.00035 x 0.0011 in. = 3.85 E-07 in2 = 0.385 sq-mils.
b) Cross-sectional area of 16 conductors = 3.85 x E-07 in2 * 16 = 6.2 sq-mils.
c) Find the current for the total cross-sectional area, 6.2 sq-mils, and a 10 °C rise using the charts in Figure A-35 through
Figure A-38, which results in 0.7 Amps.
20
August 2009
IPC-2152
17.5
15.0
C
45º
C
30º
12.5
Current in Amperes
10.0
20º
C
7.5
10ºC
6.0
5.0
4.0
3.5
3.0
2.5
2.0
1.5
1.0
.75
.50
.30
.25
.125
.062
0
0
1
5
10
20 30
50
70
100
150
200
250 300
400
500
600
700
Cross-Sectional Area (Sq-mils)
1
10
100
1000
0.0001
Width (inch)
0.001
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1-oz (0.0013 in thick)
1
1/2-oz (0.00065 in thick)
1/4-oz (0.000325 in thick)
10
IPC-2152-a-2
Figure A-2
External and Internal Conductor Sizing Chart
21
IPC-2152
August 2009
d) Divide the current by 16 conductors, 0.7/16 = 0.0438 Amps.
e) Round down = 0.04 Amps per conductor.
f) For boards that are less than [0.070 in] thick, the temperature rise will be higher. A.4.2 discusses PB thickness and conductor temperature rise.
g) If copper planes are present in the PB, then the temperature rise will be lower. It is recommended to use copper planes
for design margin and not for actual sizing of conductors. Methods for estimating the temperature effect of copper planes
are discussed in A.4.6.
Figure A-3
Parallel Conductors
Conductor Spacing: Fine line conductors and spacing as shown in Figure A-3 are easily distinguished as parallel conductors. In other cases, the temperature gradient around the conductor can determine when the parallel conductor rule should
be used. A general rule is that conductors within 25.4 mm [1.0 in] spacing should be considered parallel. The rule is based
on a 12.7 mm [0.5 in] gradient on the side of each conductor. That is the significant area of temperature change. See Figure A-4 and Figure A-5. The temperature gradient will extend to all sides of the conductor. As conductors are spaced closely
with each other their gradients overlap, which causes each of the conductors to increase in temperature. The temperature
gradients in the following figures are representative for polyimide and FR-4 PBs with no copper planes. To estimate the
change in conductor temperature rise when copper planes are present, see A.4.6.
The temperature gradient around a single conductor is illustrated in Figure A-4 and Figure A-5. Figure A-4 represents a
0.254 mm [0.010 in] wide internal conductor, with a 10 °C rise, in a 1.79 mm [0.070 in] thick polyimide PB. The numbers
on the left side of the illustration show the distance from conductor at 35 °C to the PB temperature at the distances shown.
This illustrates the temperature gradient in a PB with no copper planes. The conductor in Figure A-4 is internal and too small
to see the 35 °C temperatures. The conductor itself is at 35 °C.
Example 3: Figure A-5 represents an internal, 1-oz., 4.06 mm [0.160 in] wide conductor, in a polyimide PB that is 1.79
mm [0.070 in] thick. The PB is in still air and represents the test configuration defined in IPC-TM-650, Method 2.5.4.1. The
conductor is designed for a 10 °C rise. The conductor is large enough to show a small temperature difference between the
conductor at 35 °C and external PB temperature directly above the conductor, which is less than 1 °C cooler in a still air
environment.
When comparing the conductor temperature gradient in Figure A-4 and Figure A-5, the purpose of these two figures is to
show that, at 0.127 mm [0.5 in], there is a small temperature rise that will begin to overlap with another conductor that is
at the same temperature rise.
Figure A-6 shows two parallel 2.03 mm [0.080 in] conductors, separated by 2.54 mm [0.100 in], each with half the current
as a single 4.06 mm [0.160 in] conductor designed for a 10 °C rise. The two parallel conductors each have a 9.4 °C rise.
Figure A-7 shows the same two 2.03 mm [0.080 in] wide conductors each designed for a 10 °C rise and not following the
parallel conductor sizing rules. In this case, a 17.35 °C temperature rise results from not following the parallel conductor
sizing rules.
Figure A-8 and Figure A-9 show how the conductor temperature rise drops as separation distance between the conductors
increases. The conductors in Figure A-8 and Figure A-9 are designed following the parallel conductor-sizing rule. The conductors in Figure A-10 show the temperature rise when the parallel conductor rule is not used with 25.4 mm [1.0 in] spacing.
22
August 2009
IPC-2152
ºC
0.9 in (25.5ºC)
0.6 in (26.4ºC)
0.33 in (29ºC)
0.0 in (35ºC)
IPC-2152-a-4
Figure A-4
[0.010 in] wide (1-oz.) Conductor at 10 °C Temperature Gradient
ºC
0.506 in, 26.8 ºC
0.436 in, 27.4 ºC
0.366 in, 27.9 ºC
0.297 in, 28.6 ºC
0.226 in, 29.6 ºC
0.15 in, 30.8 ºC
0.07 in, 32.7 ºC
35 ºC
IPC-2152-a-5
Figure A-5
4.06 mm [0.160 in] Single Conductor
23
IPC-2152
August 2009
ºC
0.1 in
IPC-2152-a-6
Figure A-6
Two 2.03 mm [0.080 in] conductors (2.54 mm [0.100 in] spacing) amperage adjusted for parallel conductor
ºC
IPC-2152-a-7
Figure A-7
24
Two 2.03 mm [0.080 in] Conductors (2.54 mm [0.100 in] spacing) No amperage adjustment
August 2009
IPC-2152
ºC
0.5 in
IPC-2152-a-8
Figure A-8
Two 2.03 mm [0.080 in] Conductors (12.7 mm [0.50 in] spacing) Amperage adjusted for Parallel Conductor
ºC
IPC-2152-a-9
Figure A-9
Two 2.03 mm [0.080 in] Conductors (25.4 mm [1.0 in] spacing) Amperage adjusted for Parallel Conductor
25
IPC-2152
August 2009
ºC
IPC-2152-a-10
Figure A-10
Two 2.03 mm [0.080 in] Conductors (25.4 mm [1.0 in] spacing) No amperage adjustment
Closely related to parallel conductors are etched coils. ‘‘For applications where etched coils are to
be used, the maximum temperature rise may be obtained by using an equivalent cross-section equal to 2n times the crosssection of the conductor, and an equivalent current equal to 2n times the current in the coil, where n is equal to the number of turns.’’1
A.3.3.1 Etched Coils
Example 4: Determine the maximum current for a coil with 10 turns and which has the same size conductor as shown in
Example 2.
a) Conductor cross-sectional area = 0.385 sq-mils or 3.85E-07 sq-in.
b) The number of turns, n, is = 10
c) 2*n* cross-sectional area = 2*10*0.385 sq-mils = 7.7 sq-mils
d) Equivalent current = 2 * n * current = 0.8 Amps
e) Coil current for a 10 °C rise = 0.8 Amps / 2n = 0.04 Amps
A.3.4 Vias The cross-sectional area of a via should have at least the same cross-sectional area as the conductor or be larger
than the conductor coming into it. If the via has less cross-sectional area than the conductor, then multiple vias can be used
to maintain the same cross-sectional area as the conductor. The cross-sectional area can be calculated based on the barrel
diameter and the plating thickness. The plating thickness can be assumed to be 0.0178 mm [0.0007 in] thick unless otherwise defined. Figure A-11 illustrates the cross-sectional area of a via.
A.3.4.1 Conductor to Via to Plane If a conductor is connected to a via and the via is connected to a plane, the plane will
conduct heat away from the via and the via will run cooler than the conductor.
A.3.4.2 Microvia Microvias react to temperature rise due to current in the same manner as a through-hole via. The crosssectional area is the parameter that relates to a current level and temperature rise.
1. National Bureau of Standards Report 4283, Characterization of Metal-Insulator Laminates, Progress Report to Navy Bureau of Ships, D. S. Hoynes, May 1,
1956, page 25.
26
August 2009
IPC-2152
Cross-sectional
Area of a Via =
Π*D2
4
−
Π*d2
4
D
d
(D-d)
2
Figure A-11
Conductor Via Trace
= barrel plating thickness
IPC-2152-a-11
Via Cross-sectional Area
Conductor Via Plane
IPC-2152-a-12
Figure A-12
Via Temperature Gradient
A.4 SUPPLEMENTAL MATERIAL
A.4.1 Flex Circuits Figure 5-1 in IPC-2152 is recommended for designing flex circuit conductors. Data is not available
for evaluating temperature rise due to current in flex, although all the same rules apply including those for parallel conductors. Flex circuits will perform as conductors in thin PBs. Copper planes included in a flex design will help lower the temperature rise of a conductor.
A.4.2 PB Thickness The PB thickness has a direct impact on conductor heating. The charts presented in this appendix
represent the temperature rise in a 1.79 mm [0.070 in] thick PB with no copper planes. The conductor temperature rise will
increase as the PB thickness decreases. The thickness of the PB impacts the heat transfer path for energy to flow away from
the conductor.
Current carrying capacity testing of conductors in 0.965 mm [0.038 in] thick FR-4 PBs show results that are 30-40% higher
in temperature compared to the 1.79 mm [0.070 in] thick PB temperatures. The higher temperatures (a 40% increase) are
seen in larger conductors (2.54 vs.0.203 mm [0.100 vs. 0.008 in]). Testing with 1.50 mm [0.059 in] thick FR-4 PBs showed
temperatures that are 10-20% higher compared to the 1.79 mm [0.070 in] thick polyimide test boards.
The thermal conductivity, a contributor to the conductor temperature differences, is listed in Table A-3.
27
IPC-2152
August 2009
⁄ oz. copper conductors are similar in temperature rise for the same size cross-sectional area as 1
oz. conductors. An increase in temperature rise of 10-15% over 1 oz. conductors is observed for 2 oz. conductors and an
additional 15-20% increase for 3 oz. conductors for the same cross-sectional area. The higher percentage is for a 45 °C rise
and the lower percentage is for a 10 °C rise. These differences can be observed when reviewing the charts in Section A.6.
A.4.3 Copper Weight
12
The nominal thickness of 1 oz. copper is 0.034 mm [0.00134 in], which is the resulting thickness for 1 oz. of copper distributed evenly over one square foot of PB material on a PB layer (copper density = 0.324 lb/in3). In practice, manufactured
conductors may be thinner, so a value of 0.033 mm [0.0013 in] is used in Figure 5-2 and Figure A-15 when calculating the
conductor width. Two oz. copper is twice those values and half that thickness for 1⁄2 oz. copper. IPC-2221 specifies the
minimum acceptable copper thickness for an internal layer as shown in Table A-1. The final cross-sectional area after processing may be significantly different than the nominal value and must be considered. For example, 1 oz. is allowed to be
a minimum of 0.025 mm [0.00098 in] and, when compared to 0.036 mm [0.0014 in], this difference in thickness can cause
a 50% difference in conductor temperature rise.
Table A-1
Minimum Internal Copper Foil Thickness (For Reference Only)
Weight
Absolute Cu Min. (IPC-4562 less
10% reduction) (µm) [µin]
Maximum Variable Processing
Allowance Reduction1 (µm) [µin]
Minimum Final Finish after
Processing (µm) [µin]
18
⁄ oz. [5.10]
4.60 [181]
1.50 [59]
3.1 [122]
14
⁄ oz. [8.50]
7.70 [303]
1.50 [59]
6.2 [244]
38
⁄ oz. [12.00]
10.80 [425]
1.50 [59]
9.3 [366]
12
⁄ oz. [17.10]
15.40 [606]
4.00 [157]
11.4 [449]
1 oz. [34.30]
30.90 [1,217]
6.00 [236]
24.9 [980]
2 oz. [68.60]
61.70 [2,429]
6.00 [236]
55.7 [2,193]
3 oz. [102.90]
92.60 [3,646]
6.00 [236]
86.6 [3,409]
4 oz. [137.20]
123.50 [4,862]
6.00 [236]
117.5 [4,626]
Above 4 oz. [137.20]
IPC-4562 value
less 10% reduction
6.00 [236]
6 µm [236 µin] below
minimum thickness of
calculated 10% reduction of
foil thickness in IPC-4562
Note 1: Process allowance reduction does not allow for rework processes for weights below 1⁄2 oz. For 1⁄2 oz. and above, the process allowance reduction
allows for one rework process.
External conductors have a higher minimum than internal conductors due to plating during the final processing steps at PB
fabrication. See Table A-2, taken from IPC-2221. It is always recommended to discuss variation of the PB processing
parameters with the PB fabricator.
Conductor thickness can be verified through the use of coupons from the PB fabrication panels.
Table A-2
Minimum External Conductor Thickness (For Reference Only)
Plus Minimum
Plating for
Class 1 and 2
(20 µm) [787 µin]2
Plus Minimum
Plating for
Class 3
(25 µm) [984 µin]2
Maximum
Variable
Processing
Allowance
Reduction3
(µm) [µin]
Minimum Surface
Conductor Thickness
after Processing (µm) [µin]
Weight1
Absolute Cu Min.
(IPC-4562 less 10%
reduction)
(µm) [µin]
18
⁄ oz.
4.60 [181]
24.60 [967]
29.60 [1,165]
14
⁄ oz.
7.70 [303]
27.70 [1,091]
32.70 [1,287]
⁄ oz.
10.80 [425]
30.80 [1,213]
35.80 [1,409]
12
⁄ oz.
15.40 [606]
35.40 [1,394]
40.40 [1,591]
2.00 [79]
33.4 [1,315]
38.4 [1,512]
1 oz.
30.90 [1,217]
50.90 [2,004]
55.90 [2,201]
3.00 [118]
47.9 [1,886]
52.9 [2,083]
2 oz.
61.70 [2,429]
81.70 [3,217]
86.70 [3,413]
3.00 [118]
78.7 [3,098]
83.7 [3,295]
3 oz.
92.60 [3,646]
112.60 [4,433]
117.60 [4,630]
4.00 [157]
108.6 [4,276]
113.6 [4,472]
4 oz.
123.50 [4,862]
143.50 [5,650]
148.50 [5,846]
4.00 [157]
139.5 [5,492]
144.5 [5,689]
38
Class 1 & 2
Class 3
1.50 [59]
23.1 [909]
28.1 [1,106]
1.50 [59]
26.2 [1,031]
31.2 [1,228]
1.50 [59]
29.3 [1,154]
34.3 [1,350]
Note 1. Starting foil weight of design requirement per procurement documentation.
Note 2. Process allowance reduction does not allow for rework processes for weights below 1⁄2 oz. For 1⁄2 oz. and above, the process allowance reduction
allows for one rework process.
Note 3. Reference: Min. Cu Plating Thickness
Class 1 = 20 µm [787 µin]
Class 2 = 20 µm [787 µin]
Class 3 = 25 µm [984 µin]
28
August 2009
IPC-2152
A.4.4 Board Material The PB material thermal conductivity has a direct impact on the temperature rise of a conductor.
The differences between the FR-4 and polyimide material thermal conductivity as shown in Table A-3 have approximately
a 2% impact on conductor temperature rise in thermal models used to evaluate the material.
The thermal conductivity reported in most dielectric material data sheets is the z-axis thermal conductivity and it represents
the dielectric resin in the material. The x and y-axis thermal conductivity is higher due to the woven fibers in the laminate.
There is little information available on the thermal conductivity of laminate materials and the values listed in Table A-3 for
FR-4 and polyimide are measured values from current carrying capacity test vehicle coupons.
The thermal conductivity of copper is almost 1000 times greater than the dielectric material’s thermal conductivity and is
the reason that internal copper planes have such a significant effect on conductor temperature rise. The thermal conductivity of air, which is 10 times less than the dielectric, helps to explain why external conductors generally run hotter than internal conductors in a still air environment. Natural convection has less of an effect on the conductor temperature rise than the
materials immediately surrounding it. The materials draw attention to the thermal conductivity of copper and the effect that
a copper plane can have on heat spreading.
Table A-3
Material Thermal Conductivity
Material
Kx
W/in-C (W/m-K)
Ky
W/in-C (W/m-K)
Kz
W/in-C (W/m-K)
FR-4
Polyimide
Copper OFHC (Oxygen Free
High Thermal Conductivity)
Air
0.0124 (0.488)
0.0138 (0.543)
9.935 (391.2)
0.0124(0.488)
0.0138 (0.543)
9.935 (391.2)
0.0076 (0.299)
0.0085 (0.335)
9.935 (391.2)
0.000879 (0.0346)
0.000879 (0.0346)
0.000879 (0.0346)
A.4.5 Environments Charts in Figure 5-1 through Figure 5-5 of IPC-2152 represent conductors in PBs in still air and
vacuum environments. The environment refers to the surroundings to which the PB is exposed and operates. Conductors in
PBs operating in an air environment have a lower temperature rise than the same conductor operating in a vacuum environment. Forced air, liquid coolants and other gaseous coolants are among the environments not documented.
A.4.6 Copper Planes The factor that has the most significant impact on the temperature rise of a conductor for a given
current level and conductor size is the influence of copper planes. Whether it is a power, ground or simply a thermal plane,
the copper material of the plane helps spread the heat and lower the temperature rise of what would otherwise be a hot spot.
When designing with the charts provided in IPC-2152, copper planes add margin to the design. A single plane of copper
may be the first mitigation of a design to reduce the operating temperature. Multiple planes will lower the temperature even
more.
A.4.6.1 Single Plane Computer thermal models were created and correlated with conductor heating data collected using
1.79 mm [0.070 in] thick polyimide test vehicles. After correlating the models2, layers of copper, or plane layers, were added
to the models. Results from those models were used to develop charts that represent conductor temperature rise as a function of current for conductors in PBs with layers of copper.
Conductor temperature rise has been characterized with respect to the distance from copper planes. A single copper plane
has the most significant impact of all the variables that influence conductor temperature rise. Guidelines for estimating conductor temperature rise when a copper plane is present are given below:
a) Initial conductor temperature rise:
1) The initial conductor temperature rise represents the conductor temperature rise in a PB with dielectric only (no internal copper planes).
2) The charts represent a 1.79 mm [0.070 in] thick polyimide PB.
3) The influence of a copper plane on the conductor temperature rise is more significant for thinner PBs and PBs with
lower dielectric thermal conductivity values than polyimide and FR-4.
2. The finite element models were developed in Harvard Thermal (ANSYS) TAS and TASPCB/Iceboard thermal analysis software. They were correlated to the
conductor heating data collected in still air environments. After the models were correlated with the test data, single copper planes and then two copper
planes were added to the models for the purpose of simulating power, ground or thermal planes.
29
IPC-2152
August 2009
b) Distance from conductor to copper plane. The closer the conductor is to the plane the lower the temperature rise of the
conductor.
c) Area of copper plane. The size of the internal copper plane impacts the amount of heat spreading that can occur:
1) Below 9 sq-in the impact has not been completely characterized, although the effect is reduced.
2) From 9 sq-in to 40 sq-in the effect is increased by approximately 10%.
3) Above 40 sq-in the effect remains constant.
d) Thickness of copper plane. As the amount of copper thickness increases, the temperature rise of the conductor decreases.
e) Number of copper planes. As the number of planes increase, the conductor temperature rise will decrease.
A.4.6.2 Conductor Distance from Plane Figure A-13 provides reduction factors for temperature rise as a function of copper plane size and distance from conductor to plane in a 1.79 mm [0.070 in] thick polyimide PB. The set of curves in Figure A-13 may be used in conjunction with the charts in Section 6 to calculate improvement from a nearby plane.
The first step is to calculate a conductor temperature rise or ΔT using the appropriate chart. The second step is to determine
the size of a copper plane in the PB and the distance from the conductor to the plane. For example, assume a solid, 1 oz.,
copper ground plane in a 127 mm [5.0 in] long and 203 mm [8.0 in] wide PB (25,806 mm2 [40 in2]). In addition, assume
that the conductor is several dielectric layers from the copper plane. If the distance from the conductor to the plane is 0.51
mm [0.020 in], then the conductor temperature rise will be approximately 0.42 times the temperature rise calculated. If the
conductor were 0.127 mm [0.005 in] from a 2 oz. copper plane, the temperature rise would be 0.29 times the temperature
rise. Therefore, if a 10 °C rise were calculated from the appropriate chart, then the temperature rise would be 4.2 °C in the
first case, and 2.9 °C in the second case.
Figure A-13 is derived using thermal analysis software; it assumes solid copper planes and therefore may be nonconservative in estimating the reduction in conductor temperature rise. Therefore it is recommended to only use this chart
for estimating temperature margin in a conductor temperature rise calculation.3
ΔT with Cu Plane
.070" Thick Polyimide Board
Coefficient
(Portion of No Plane TMCΔT)
0.60
0.50
1 oz plane .040 in from trace
0.40
1 oz plane .020 in from trace
1 oz plane .005 in from trace
030
2 oz plane .005 in from trace
0.20
0.10
0.00
0
20
40
60
80
100
120
Board Area, in2
Copyright 2006©Thermal Man Inc.
Figure A-13
Distance from Conductor to Copper Plane
IPC-2152-a-4
3
3. The copper planes do not take into account the ‘‘Swiss-cheese effect’’ from vias, which is described in A.5.3. The planes are assumed continuous solid planes.
30
August 2009
IPC-2152
A.5 ADDITIONAL TOPICS
A.5.1 Heat Transfer from a Conductor Heat transfer from a conductor is fairly complex when all aspects of a design are
taken into consideration. The PB thickness, copper thickness, length of conductor, number of layers, PB material, environment (earth, vacuum, forced air, high-altitude), vias, odd shaped copper planes, multiple layers, ‘‘Swiss-cheese effect’’ due
to vias in planes, mounting configurations, airflow, components, radiation and convection are all variables that impact the
temperature rise of a conductor in a PB. These variables don’t all affect the temperature rise equally and the key is to understand what the primary and secondary factors are that affect the conductor temperature rise. Working with a very simple
circuit, adding one complexity at a time, and discussing areas that have the biggest impact on the temperature rise of a conductor is the focus of this section. Consider Figure A-14 for the beginning of this discussion.
A
A-A
Top View
I
A
Side View
IPC-2152-a-14
Figure A-14
Single Conductor in a PB
Figure A-14 represents a single internal conductor in a PB. When current is applied to the conductor, it will heat up until it
stabilizes at some temperature. Energy (Joules) will conduct at some rate (Joules per second (Watts)) out from the conductor into the PB. That energy will spread (conduct) into the PB until it reaches the external surfaces of the PB where it will
convect and radiate away from the PB. It is this basic construction of a conductor in a PB that constitutes the ‘‘baseline’’
configuration and the design rules for sizing conductors.
As PBs get more complicated, the conductor sizing rules become more detailed. Knowing that the conductor temperature
rise is due to the power that is dissipated in the conductor is a fundamental concept. The power dissipation in the conductor, the heat transfer path from the conductor through the PB and the heat transfer from the PB to the ambient determine the
temperature rise. The amount of copper in a PB has a significant impact on the temperature rise of the conductor in the PB.
The scope of this discussion is limited to a basic understanding of conductor heating, power dissipation in a conductor, the
conductor resistance and PB thermal resistance.
A.5.2 Conductor Power Dissipation The rate that the energy leaves the conductor is the conductor power dissipation. The
conductor power can be calculated using Equation [A-1] and Equation [A-2]. The power is a function of the conductor electrical resistance and the current applied to the conductor. The power dissipation is also the current multiplied by the voltage drop across the conductor.
P = Q = I2R
[A-1]
Where: P = power dissipation (Watts)
Q = power dissipation = energy flow (Joules/sec)
I = current (Amps)
R = conductor electrical resistance (Ohm)
P = V*I
[A-2]
Where: P = power dissipation (Watts)
V = voltage drop across the length of the conductor (V)
I = current (Amps)
The conductor electrical resistance can be calculated using Equation [A-3].
When calculating the resistance of the conductor at a temperature other than 25 °C, Equation [A-4] is also used.
A.5.2.1 Conductor Electrical Resistance
31
IPC-2152
August 2009
R =
L
ρ
A ν
[A-3]
Where: ρν = volume resistivity
= 7.55E-07 ohm in2/in at 25 °C 1⁄2 oz.
= 7.09E-07 ohm in2/in at 25 °C 1 oz. and greater
A = cross-sectional area (in2
L = length (in)
R = resistance in ohms
Rt2 = Rt1 (1+ αt1 [t2 - t1])
[A-4]
Where: Rt2 = R at new temperature (Ohm)
Rt1 = R at t1
αt1 = temperature coefficient = 0.00385 @ 25 °C (C-1)
t1 = initial temperature (°C)
t2 = new temperature (°C)
Test data and cross-sections of conductors were used to compare against the values of resistivity listed above. The value for
1⁄2 oz. copper and the value for 1 oz. and greater (2 oz., 3 oz., etc.) are from IPC-TM-650, Method 2.5.4.1. The values from
the IPC test method compared well with measured data. For further discussion on the tolerance of the resistivity values, see
Reference [1] in Section A.7.
A.5.3 Odd Shaped Geometries and Swiss-Cheese Effect High current is often applied to copper planes that deliver the
power to various locations in the printed design. It is not uncommon for these copper planes to be odd shaped geometries.
The simple conductor sizing charts become limited in their use for these applications.
A software program is required to perform this analysis.
A technique for evaluating the temperature distribution in copper planes that have odd
shaped geometries, as well as the result of many vias and cutouts, is by using a voltage drop analysis. Voltage drop in an
odd shaped geometry can only be calculated accurately with numerical techniques. The easiest way is to use software tools
that are designed for this type of problem.
A.5.3.1 Voltage Drop Analysis4
There is a direct analogy between thermal resistance and electrical resistance. Because of this, thermal analysis tools can be
used to calculate voltage drop rather than temperature drop. The following summarizes the analogy between thermal and
voltage drop analysis.
Temperature (Degrees)
Heat flux (Watts)
Thermal conductivity (Watts/(in-C)
Resistance (Degrees/Watt)
≥
≥
≥
≥
Voltage (Volts)
Current (Amps)
Electrical conductivity (Mhos/in)5
Resistance (ohms or 1/Mhos)
Mho is a unit of conductance equal to the reciprocal of an ohm.
The voltage drop is calculated based on actual dimensions for the analysis. If plate elements are used to represent a copper
plane in a PB, the actual PB dimensions are needed and the actual copper thickness is required.
A.5.3.2 Voltage Sources A voltage source is defined as a point where voltage is applied to a circuit. This would typically
be a power supply. In a thermal analysis tool, this is analogous to defining a boundary temperature.
A.5.3.3 Current Source (or Sink) A point where a defined amount of current is added or removed is considered a heat
load in a thermal analysis tool. If a component draws a specified current at a point in the PB model, the current would be
represented as a negative heat load at that point. If a voltage source acts as a constant current source, as opposed to a constant voltage source, it would be represented as a positive heat load.
A.5.3.4 Electrical Conductivity For geometric elements such as plates, bricks and tetrahedrons, thermal conductivity
should be in units of Mhos/length where Mhos equals 1/ohm. Units of length must be consistent with those used in the rest
of the model.
4. ANSYS Thermal Analysis System (TAS) Thermal Modeling Software is an example of a program providing this analysis.
5. Mho is more properly referred to as siemens = amperes/volts.
32
August 2009
IPC-2152
A.5.4 HDI Fine line and space, thin copper and small PBs create new design challenges. When PBs get smaller than 76.2
x 76.2 mm [3.0 x 3.0 in], the current carrying capacity decreases. In addition, as PB thickness decreases the current carrying capacity decreases. The charts in IPC-2152 are limited to PB sizes larger than 76.2 x 76.2 mm [3.0 x 3.0 in].
HDI products may include unconventional design methods, ultra-thin or ultra-fine conductor patterns or be constructed of
unconventional conductor or insulation materials resulting in a system with lower current carrying capacity than indicated
in this standard. Therefore, designers should exercise caution and test representative products to validate performance. HDI
product features potentially limiting current carrying capacity may include (but are not limited to):
a) Conductor lines less than 0.05 mm [0.0020 in] width
b) Finished conductor thickness less than 18 µm [0.0007 in]
c) Conductive paste or conductive bump via interconnections
d) Conductive polymer conductor patterns
e) Unreinforced polymer insulation materials
f) Ultra-thin dielectric materials
g) Embedded passive devices
A.5.5 High-Speed As signal speed increases, the current will flow through the perimeter of a conductor or the outer skin.
The frequency and the conductor material determine the thickness of the outer layer (skin depth) of the conductor in which
the current flows. As the frequency increases, the skin depth decreases and the resistance to the current flow increases. The
conductor temperature rise in high-speed circuits can be estimated based on the calculated cross-sectional area and an average current. Skin depths have been calculated for a number of frequencies. The effective resistance in a conductor can be
calculated using the skin depth along the perimeter of the conductor. Current densities will occur in the cross-section of the
conductor due to copper planes. In addition, current tends to flow through the smooth sides of the conductor, which lowers
the cross-sectional area that the current will flow. Each of these considerations will increase the effective resistance to the
current flow. Table A-4 is included as a resource for calculating skin depth in conductors.
Table A-4
Skin Depth Parameters
Skin Depth in Copper at Select Frequencies1
According to Lance(2), the Skin Depth δ of a particular metal with a Resistivity ρ at a frequency F is equal to:
δ = [ρ/(Π * µ * F)]1/2, where Π ≈ 3.141592654, and µ ≡ 4 * Π * 10-7.
According to Ramo(3), the surface resistivity Rs of a particular metal with a Resistivity ρ is equal to: Rs = [ρ * Π * µ * F]1/2.
Metal
Copper
ρ(4)
(µΩ−cm)
1.678
Rs (Ω/sq)
(1E−9 √F
257
δ (1 GHz)
2.06
δ (5 GHz)
0.922
Skin Depth (µm)
δ (10 GHz)
δ (15 GHz)
0.652
0.532
δ (20 GHz)
0.461
δ (26 GHz)
0.412
1.
Gathered and calculated by Pat Zabinski, Mayo Foundation, Rochester, MN 55905, January 3, 1995.
Lance, A. L., ‘‘Introduction to Microwave Theory and Measurements,‘‘ McGraw Hill, New York, 1964, page 30.
Ramo, S., et. al., ‘‘Fields and Waves in Communication Electronics, 2nd ed.,‘‘ Wiley, 1984, pages 147-153.
4.
Values for Resistivity, ρ, were found in the ‘‘CRC: Handbook of Chemistry and Physics, 75th ed,‘‘ 1994, at 20°C.
2.
3.
A.6 CONDUCTOR SIZING CHARTS
Charts listed in 5.1 and 5.2 of the IPC-2152 are the 3 oz. external charts. External and internal conductors experience
approximately the same temperature rise when current is applied to them. This is true in both still-air and vacuum environments. The 3 oz. charts show the least current carrying capacity when compared to the 1⁄2 oz., 1 oz., and 2 oz. charts; therefore they were selected as the single chart to be included in the main document.
The chart that is recommended for all conductors (Figure 5-1 of IPC-2152) is conservative for internal and external conductors in air and vacuum environments. Its origin and information related to it are further discussed in A.7.1.
The remaining charts included in this appendix are provided for those that are looking for more detailed information regarding conductor temperature rise in PB design.
A.6.1 Conductor Sizing Charts for Still Air Environments
The following charts are for external and internal conductors
in still air environments.
33
IPC-2152
August 2009
A.6.1.1 Still Air Environment Charts in Imperial (Inch) Units Figure A-15 through Figure A-38 represent charts for internal and external conductors in still air environments in imperial (inch) units.
A.6.1.1.1 3 oz. Conductor Sizing Charts, Still Air, External, Imperial (Inch) Units
3 oz Air Ext Poly 0.07
100
Current (Amps)
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
5ºC
10
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-Sectional Area (Sq-mils)
1
10
100
1000
0.0001
0.001
Width (inch)
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1-oz (0.0013 in thick)
1
1/2-oz (0.00065 in thick)
1/4-oz (0.000325 in thick)
10
IPC-2152-a-15
Figure A-15
34
3 oz. External Conductors (Still Air) Log (5 - 700 Sq-mils)
August 2009
IPC-2152
3 oz Air Ext Poly 0.07
30
100ºC
25
75ºC
60ºC
Current (Amps)
20
45ºC
15
30ºC
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
600
700
Cross-Sectional Area (Sq-mils)
Figure A-16
800
IPC-2152-a-16
3 oz. External Conductors (Still Air) (5 - 700 Sq-mils)
3 oz Air Ext Poly 0.07
100ºC
75ºC
60ºC
45ºC
5
30ºC
4.5
4
20ºC
Current (Amps)
3.5
3
10ºC
2.5
2
5ºC
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
Cross-Sectional Area (Sq-mils)
Figure A-17
70
80
90
100
IPC-2152-a-17
3 oz. External Conductors (Still Air) (5 - 100 Sq-mils)
35
IPC-2152
August 2009
3 oz Air Ext Poly 0.07
100ºC
5
75ºC
4.5
60ºC
4
45ºC
3.5
Current (Amps)
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-a-18
Figure A-18
36
3 oz. External Conductors (Still Air) (5 - 50 Sq-mils)
August 2009
IPC-2152
A.6.1.1.2 3 oz. Conductor Sizing Charts, Still Air, Internal, Imperial (Inch) Units
3 oz Air Int Poly 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
5ºC
Current (Amps)
10
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-Sectional Area (Sq-mils)
1
10
100
1000
0.0001
Width (inch)
0.001
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1-oz (0.0013 in thick)
1
1/2-oz (0.00065 in thick)
1/4-oz (0.000325 in thick)
10
IPC-2152-a-19
Figure A-19
3 oz. Internal Conductors (Still Air) Log (5 - 700 Sq-mils)
37
IPC-2152
August 2009
3 oz Air Int Poly 0.07
30
100ºC
25
75ºC
60ºC
Current (Amps)
20
45ºC
15
30ºC
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
600
700
800
Cross-Sectional Area (Sq-mils)
IPC-2152-a-20
Figure A-20
3 oz. Internal Conductors (Still Air) (5 - 700 Sq-mils)
3 oz Air Int Poly 0.07
100ºC
5
75ºC
30ºC
45ºC
60ºC
4.5
20ºC
4
Current (Amps)
3.5
3
10ºC
2.5
5ºC
2
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
Cross-Sectional Area (Sq-mils)
Figure A-21
38
3 oz. Internal Conductors (Still Air) (5 - 100 Sq-mils)
70
80
90
100
IPC-2152-a-21
August 2009
IPC-2152
3 oz Air Int Poly 0.07
100ºC
5
75ºC
60ºC
4.5
45ºC
Current (Amps)
4
3.5
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-a-22
Figure A-22
3 oz. Internal Conductors (Still Air) (5 - 50 Sq-mils)
39
IPC-2152
August 2009
A.6.1.1.3 2 oz. Conductor Sizing Charts, Still Air, External, Imperial (Inch) Units
2 oz Air Poly Ext 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
5ºC
Current (Amps)
10
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-sectional Area (Sq-mils)
1
10
100
1000
0.0001
Width (inch)
0.001
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1-oz (0.0013 in thick)
1
1/2-oz (0.00065 in thick)
1/4-oz (0.000325 in thick)
10
IPC-2152-a-23
Figure A-23
40
2 oz. External Conductors (Still Air) Log (5 - 700 Sq-mils)
August 2009
IPC-2152
2 oz Air Poly Ext 0.07
30
100ºC
25
75ºC
60ºC
Current (Amps)
20
45ºC
30ºC
15
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
600
700
800
Cross-Sectional Area (Sq-mils)
IPC-2152-a-24
Figure A-24
2 oz. External Conductors (Still Air) (5 - 700 Sq-mils)
2 oz Air Poly Ext 0.07
100ºC
75ºC
60ºC
45ºC
5
30ºC
4.5
20ºC
4
Current (Amps)
3.5
10ºC
3
2.5
5ºC
2
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
Cross-Sectional Area (Sq-mils)
Figure A-25
70
80
60
100
IPC-2152-a-25
2 oz. External Conductors (Still Air) (5 - 100 Sq-mils)
41
IPC-2152
August 2009
2 oz Air Poly Ext 0.07
100ºC
75ºC
5
4.5
60ºC
4
45ºC
Current (Amps)
3.5
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-a-26
Figure A-26
42
2 oz. External Conductors (Still Air) (5 - 50 Sq-mils)
August 2009
IPC-2152
A.6.1.1.4 2 oz. Conductor Sizing Charts, Still Air, Internal, Imperial (Inch) Units
2 oz Air Int Poly 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
Current (Amps)
10
5ºC
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-Sectional Area (Sq-mils)
1
10
100
1000
0.0001
0.001
Width (inch)
0.01
0.1
3-oz(0.0039 in thick)
2-oz(0.0026 in thick)
1-oz(0.0013 in thick)
1
1/2-oz(0.00065 in thick)
1/4-oz(0.000325 in thick)
10
IPC-2152-a-27
Figure A-27 2 oz. Internal Conductors (Still Air) Log (5 - 700 Sq-mils)
43
IPC-2152
August 2009
2 oz Air Int Poly 07
100ºC
30
75ºC
25
60ºC
Current (Amps)
20
45ºC
30ºC
15
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
600
700
Cross-Sectional Area (Sq-mils)
IPC-2152-a-28
Figure A-28
2 oz. Internal Conductors (Still Air) (5 - 700 Sq-mils)
2 oz Air Int Poly 0.07
100ºC
75ºC
60ºC
45ºC
30ºC
5
4.5
20ºC
4
Current (Amps)
3.5
10ºC
3
2.5
5ºC
2
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
Cross-Sectional Area (Sq-mils)
Figure A-29
44
2 oz. Internal Conductors (Still Air) (5 - 100 Sq-mils)
70
80
90
100
IPC-2152-a-29
August 2009
IPC-2152
2 oz Air Int Poly 0.07
100ºC
75ºC
60ºC
5
4.5
45ºC
Current (Amps)
4
30ºC
3.5
3
20ºC
2.5
10ºC
2
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-a-30
Figure A-30
2 oz. Internal Conductors (Still Air) (5 - 50 Sq-mils)
45
IPC-2152
August 2009
A.6.1.1.5 1 oz. Conductor Sizing Charts, Still Air, Internal, Imperial (Inch) Units
1 oz Air Int Poly 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10
Current (Amps)
10ºC
5ºC
2ºC
1ºC
1
0.1
0
10
100
1000
Cross-Sectional Area (Sq-mils)
IPC-2152-a-31
Figure A-31
1 oz. Internal Conductors (Still Air) Log (5 - 700 Sq-mils)
1 oz Air Int Poly 0.07
100ºC
30
75ºC
60ºC
25
45ºC
Current (Amps)
20
30ºC
15
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
600
700
800
Cross-Sectional Area (Sq-mils)
IPC-2152-a-32
Figure A-32
46
1 oz. Internal Conductors (Still Air) (5 - 700 Sq-mils)
August 2009
IPC-2152
1 oz Air Int Poly 07
100ºC
75ºC
60ºC
45ºC
30ºC
5
20ºC
4.5
4
Current (Amps)
3.5
10ºC
3
2.5
5ºC
2
1.5
2ºC
1ºC
1
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Cross-Sectional Area (Sq-mils)
IPC-2152-a-33
Figure A-33
1 oz. Internal Conductors (Still Air) (5 - 100 Sq-mils)
1 oz Air Int Poly 0.07
100ºC
75ºC
60ºC
5
45ºC
4.5
4
30ºC
Current (Amps)
3.5
20ºC
3
2.5
10ºC
2
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-a-34
Figure A-34
1 oz. Internal Conductors (Still Air) (5 - 50 Sq-mils)
47
IPC-2152
August 2009
A.6.1.1.6 1⁄2 oz. Conductor Sizing Charts, Still Air, Internal, Imperial (Inch) Units
1/2 oz Air Int Poly 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10
Current (Amps)
10ºC
5ºC
2ºC
1ºC
1
0.1
1
100
10
1000
Cross-Sectional Area (Sq-mils)
IPC-2152-a-35
Figure A-35
⁄ oz. Internal Conductors (Still Air) Log (5 - 700 Sq-mils)
12
1/2 oz Air Int Poly 0.07
100ºC
30
75ºC
25
60ºC
Current (Amps)
45ºC
20
30ºC
15
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
Cross-Sectional Area (Sq-mils)
Figure A-36
48
⁄ oz. Internal Conductors (Still Air) (5 - 700 Sq-mils)
12
600
700
800
IPC-2152-a-36
August 2009
IPC-2152
1/2 oz Air Int Poly 0.07
100ºC
75ºC
60ºC
45ºC
30ºC
5
20ºC
4.5
4
Current (Amps)
3.5
10ºC
3
2.5
5ºC
2
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Cross-Sectional Area (Sq-mils)
Figure A-37
IPC-2152-a-37
⁄ oz. Internal Conductors (Still Air) (5 - 100 Sq-mils)
12
1/2 oz Air Int Poly 0.07
75ºC
100ºC
60ºC
5
45ºC
4.5
4
30ºC
Current (Amps)
3.5
20ºC
3
2.5
10ºC
2
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
Cross-Sectional Area (Sq-mils)
Figure A-38
40
45
50
IPC-2152-a-38
⁄ oz. Internal Conductors (Still Air) (5 - 50 Sq-mils)
12
49
IPC-2152
August 2009
A.6.1.2 Still Air Environment Charts in SI (Metric) Units Figure A-39 through Figure A-62 represent charts for internal
and external conductors in still air environments in SI (metric) units.
A.6.1.2.1 3 oz. Conductor Sizing Charts, Still Air, External, SI (Metric) Units
3 oz Air Int Poly 0.07
100
100ºC
75ºC
60ºC
Current (Amps)
45ºC
30ºC
20ºC
10ºC
5ºC
10
2ºC
1ºC
1
0
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
0.001
0.01
0.01
0.1
1
Width (mm)
0.1
1
3-oz(0.099 mm thick)
2-oz(0.066 mm thick)
10
1-oz(0.033 mm thick)
1/2-oz(0.0165 mm thick)
1/4-oz(0.00826 mm thick)
100
IPC-2152-a-39
Figure A-39
50
3 oz. External Conductors (Still Air) Log (0.001 - 0.5 Sq-mm)
August 2009
IPC-2152
3 oz Ext Air Poly 0.07
Current (Amps)
35
30
100ºC
25
75ºC
60ºC
20
45ºC
30ºC
15
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0.1
0
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
Figure A-40
IPC-2152-a-40
3 oz. External Conductors (Still Air) (0 - 0.5 Sq-mm)
3 oz Ext Air Poly 0.07
100ºC
10
75ºC
9
60ºC
8
45ºC
Current (Amps)
7
6
30ºC
5
20ºC
4
10ºC
3
5ºC
2
2ºC
1ºC
1
0
0
0.01
0.02
0.03
0.04
0.05
0.06
Cross-Sectional Area (Sq-mm)
Figure A-41
0.07
0.08
0.09
0.1
IPC-2152-a-41
3 oz. External Conductors (Still Air) (0 - 0.1 Sq-mm)
51
IPC-2152
August 2009
3 oz Ext Air Poly 0.07
100ºC
5
75ºC
4.5
60ºC
4
45ºC
Current (Amps)
3.5
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
Cross-Sectional Area (Sq-mm)
Figure A-42
52
3 oz. External Conductors (Still Air) (0 - 0.03 Sq-mm)
0.025
0.03
IPC-2152-a-42
August 2009
IPC-2152
A.6.1.2.2 3 oz. Conductor Sizing Charts Still Air, Internal, SI (Metric) Units
3 oz Air Int Poly 0.07
100ºC
75ºC
60ºC
45ºC
Current (Amps)
30ºC
20ºC
10ºC
5ºC
2ºC
1ºC
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
0.01
0.1
1
Width (mm)
0.001
3-oz(0.099 mm thick)
2-oz(0.066 mm thick)
1-oz(0.033 mm thick)
1/2-oz(0.0165 mm thick)
1/4-oz(0.00826 mm thick)
IPC-2152-a-43
Figure A-43
3 oz. Internal Conductors (Still Air) Log (0 - 700 Sq-mm)
53
IPC-2152
August 2009
3 oz Air Int Poly 0.07
35
100ºC
30
75ºC
25
Current (Amps)
60ºC
45ºC
20
30ºC
15
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
Cross-Sectional Area (Sq-mm)
Figure A-44
0.5
IPC-2152-a-44
3 oz. Internal Conductors (Still Air) (0 - 0.5 Sq-mm)
3 oz Air Int Poly 0.07
100ºC
10
75ºC
60ºC
9
45ºC
8
Current (Amps)
7
30ºC
6
20ºC
5
4
10ºC
3
5ºC
2
2ºC
1ºC
1
0
0
0.02
0.04
0.06
Cross-Sectional Area (Sq-mm)
Figure A-45
54
3 oz. Internal Conductors (Still Air) (0 - 0.1 Sq-mm)
0.08
0.1
IPC-2152-a-45
August 2009
IPC-2152
3 oz Air Int Poly 0.07
100ºC
75ºC
5
60ºC
4.5
45ºC
4
Current (Amps)
3.5
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
Cross-Sectional Area (Sq-mm)
Figure A-46
0.025
0.03
IPC-2152-a-46
3 oz. Internal Conductors (Still Air) (0 - 0.03 Sq-mm)
55
IPC-2152
August 2009
A.6.1.2.3 2 oz. Conductor Sizing Charts Still Air, External, SI (Metric) Units
2 oz Air Poly Ext 0.07
100
100ºC
75ºC
60ºC
Current (Amps)
45ºC
30ºC
20ºC
10
10ºC
5ºC
2ºC
1ºC
1
0.1
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
0.001
0.01
0.01
0.1
1
Width (mm)
0.1
1
10
3-oz (0.099 mm thick)
2-oz (0.066 mm thick)
1-oz (0.033 mm thick)
1/2-oz (0.0165 mm thick)
1/4-oz (0.00826 mm thick)
100
IPC-2152-a-47
Figure A-47
56
2 oz. External Conductors (Still Air) Log (0.001 - 0.5 Sq-mm)
August 2009
IPC-2152
2 oz Air Poly Ext 0.07
100ºC
30
75ºC
25
Current (Amps)
60ºC
45ºC
20
30ºC
15
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
IPC-2152-a-48
Figure A-48
2 oz. External Conductors (Still Air) (0.001 - 0.5 Sq-mm)
2 oz Air Poly Ext 0.07
75ºC
100ºC
10
60ºC
9
8
45ºC
Current (Amps)
7
30ºC
6
20ºC
5
4
10ºC
3
5ºC
2
2ºC
1ºC
1
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-49
Figure A-49
2 oz. External Conductors (Still Air) (0 - 0.1 Sq-mm)
57
IPC-2152
August 2009
2 oz Air Poly Ext 0.07
100ºC
5
75ºC
4.5
60ºC
4
45ºC
Current (Amps)
.3.5
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Cross-Sectional Area (Sq-mm)
IPC-2152-a-50
Figure A-50
58
2 oz. External Conductors (Still Air) (0 - 0.03 Sq-mm)
August 2009
IPC-2152
A.6.1.2.4 2 oz. Conductor Sizing Charts Still Air, Internal, SI (Metric) Units
2 oz Air Poly Int 0.07
100
100ºC
75ºC
60ºC
Current (Amps)
45ºC
30ºC
20ºC
10ºC
5ºC
10
2ºC
1ºC
0
0.1
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
0.001
0.01
0.01
0.1
1
Width (mm)
0.1
1
3-oz (0.099 mm thick)
2-oz (0.066 mm thick)
10
1-oz (0.033 mm thick)
1/2-oz (0.0165 mm thick)
1/4-oz (0.00826 mm thick)
100
IPC-2152-a-51
Figure A-51
2 oz. Internal Conductors (Still Air) Log (0 - 0.5 Sq-mm)
59
IPC-2152
August 2009
2 oz Air Poly Int 0.07
35
100ºC
30
75ºC
Current (Amps)
25
60ºC
45ºC
20
30ºC
15
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
Figure A-52
IPC-2152-a-52
2 oz. Internal Conductors (Still Air) (0 - 0.5 Sq-mm)
2 oz Air Poly Int 0.07
100ºC
75ºC
10
60ºC
9
45ºC
8
Current (Amps)
7
30ºC
6
20ºC
5
4
10ºC
3
5ºC
2
2ºC
1ºC
1
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-53
Figure A-53
60
2 oz. Internal Conductors (Still Air) (0 - 0.1 Sq-mm)
August 2009
IPC-2152
2 oz Air Poly Int 0.07
100ºC
75ºC
5
60ºC
4.5
45ºC
Current (Amps)
4
3.5
30ºC
3
20ºC
2.5
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Cross-Sectional Area (Sq-mm)
IPC-2152-a-54
Figure A-54
2 oz. Internal Conductors (Still Air) (0 - 0.03 Sq-mm)
61
IPC-2152
August 2009
A.6.1.2.5 1 oz. Conductor Sizing Charts Still Air, Internal, SI (Metric) Units
1 oz Int Air Poly 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
5ºC
Current (Amps)
10
2ºC
1ºC
1
0.1
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-55
Figure A-55
1 oz. Internal Conductors (Still Air) Log (0 - 0.1 Sq-mm)
1 oz Int Air Poly 0.07
100ºC
35
75ºC
30
60ºC
Current (Amps)
25
45ºC
20
30ºC
15
20ºC
10ºC
10
5ºC
5
2ºC
1ºC
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
IPC-2152-a-56
Figure A-56
62
1 oz. Internal Conductors (Still Air) (0 - 0.5 Sq-mm)
August 2009
IPC-2152
1 oz Int Air Poly 0.07
100ºC
75ºC
60ºC
10
9
45ºC
Current (Amps)
8
30ºC
7
6
20ºC
5
4
10ºC
3
5ºC
2
2ºC
1ºC
1
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-57
Figure A-57
1 oz. Internal Conductors (Still Air) (0 - 0.1 Sq-mm)
63
IPC-2152
August 2009
1 oz Int Air Poly 0.07
100ºC
75ºC
60ºC
5
45ºC
4.5
4
30ºC
Current (Amps)
3.5
20ºC
3
2.5
10ºC
2
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Cross-Sectional Area (Sq-mm)
IPC-2152-a-58
Figure A-58
64
1 oz. Internal Conductors (Still Air) (0 - 0.03 Sq-mm)
August 2009
IPC-2152
A.6.1.2.6 1⁄2 oz. Conductor Sizing Charts Still Air, Internal, SI (Metric) Units
1/2 oz Air Int Poly 0.07
100
Current (Amps)
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10
10ºC
5ºC
2ºC
1ºC
1
0.1
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-59
Figure A-59
⁄ oz. Internal Conductors (Still Air) Log (0 - 0.5 Sq-mm)
12
1/2 oz Air Int Poly 0.07
100ºC
35
75ºC
30
60ºC
25
Current (Amps)
45ºC
20
30ºC
15
20ºC
10ºC
10
5ºC
5
2ºC
1ºC
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
IPC-2152-a-60
Figure A-60
⁄ oz. Internal Conductors (Still Air) (0 - 0.5 Sq-mm)
12
65
IPC-2152
August 2009
1/2 oz Air Int Poly 0.07
100ºC
75ºC
60ºC
10
9
45ºC
8
30ºC
Current (Amps)
7
6
20ºC
5
10ºC
4
3
5ºC
2
2ºC
1ºC
1
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-61
Figure A-61
66
⁄ oz. Internal Conductors (Still Air) (0 - 0.1 Sq-mm)
12
August 2009
IPC-2152
1/2 oz Air Int Poly 0.07
75ºC
100ºC
60ºC
5
4.5
45ºC
4
30ºC
Current (Amps)
3.5
3
20ºC
2.5
10ºC
2
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Cross-Sectional Area (Sq-mm)
IPC-2152-a-62
Figure A-62
⁄ oz. Internal Conductors (Still Air) (0 - 0.03 Sq-mm)
12
67
IPC-2152
August 2009
A.6.2 Conductor Sizing Charts for Vacuum/Space Environments The following charts are for external and internal conductors in vacuum or Space environments. They can also be considered as a conservative estimate for high altitude requirements.
Figure A-63 through Figure A-74 represent charts
for internal and external conductors in vacuum/space environments in imperial (inch) units.
A.6.2.1 Vacuum/Space Environment Charts in Imperial (Inch) Units
A.6.2.1.1 3 oz. Conductor Sizing Charts, Vacuum, Imperial (Inch) Units
3 oz Vac Poly 0.07
Current (Amps)
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10
10ºC
5ºC
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-Sectional Area (Sq-mils)
1
10
100
1000
0.0001
Width (inch)
0.001
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1
1-oz (0.0013 in thick)
1/2-oz (0.00065 in thick)
1/4-oz (0.000325 in thick)
10
IPC-2152-a-63
Figure A-63
68
3 oz. Conductors (Vacuum) Log (5 - 700 Sq-mils)
August 2009
IPC-2152
3 oz Vac Poly 0.07
30
Current (Amps)
25
100ºC
75ºC
20
60ºC
45ºC
15
30ºC
20ºC
10
10ºC
5
5ºC
2ºC
1ºC
0
0
100
200
300
400
500
600
700
800
Cross-Sectional Area (Sq-mils)
IPC-2152-a-64
Figure A-64
3 oz. Conductors (Vacuum) (0 - 700 Sq-mils)
3 oz Vac Poly 0.07
100ºC
75ºC
60ºC
45ºC
5
4.5
30ºC
4
Current (Amps)
3.5
20ºC
3
2.5
10ºC
2
5ºC
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Cross-Sectional Area (Sq-mils)
IPC-2152-a-65
Figure A-65
3 oz. Conductors (Vacuum) (0 - 100 Sq-mils)
69
IPC-2152
August 2009
3 oz Vac Poly 0.07
100ºC
5
75ºC
4.5
60ºC
Current (Amps)
4.5
4
45ºC
3.5
30ºC
3
20ºC
2.5
10ºC
2
5ºC
1.5
2ºC
1ºC
1
0.5
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-a-66
Figure A-66
70
3 oz. Conductors (Vacuum) (5 - 50 Sq-mils)
August 2009
IPC-2152
A.6.2.1.2 2 oz. Conductor Sizing Charts, Vacuum, Imperial (Inch) Units
2 oz Vac Poly 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10
Current (Amps)
10ºC
5ºC
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-Sectional Area (Sq-mils)
1
10
100
1000
0.0001
Width (inch)
0.001
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1-oz (0.0013 in thick)
1
1/2-oz (0.00065 in thick)
1/4-oz (0.000325 in thick)
10
IPC-2152-a-67
Figure A-67
2 oz. Conductors (Vacuum) Log (5 - 700 Sq-mils)
71
IPC-2152
August 2009
2 oz Vac Poly 0.07
30
25
100ºC
75ºC
20
Current (Amps)
60ºC
45ºC
15
30ºC
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
600
700
800
Cross-Sectional Area (Sq-mils)
IPC-2152-a-68
Figure A-68
2 oz. Conductors (Vacuum) (5 - 700 Sq-mils)
2 oz Vac Poly 0.07
100ºC
75ºC
60ºC
45ºC
5
4.5
30ºC
4
3.5
20ºC
Current (Amps)
3
2.5
10ºC
2
5ºC
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Cross-Sectional Area (Sq-mils)
IPC-2152-a-69
Figure A-69
72
2 oz. Conductors (Vacuum) (5 - 100 Sq-mils)
August 2009
IPC-2152
2 oz Vac Poly 0.07
100ºC
5
75ºC
4.5
60ºC
4
45ºC
3.5
Current (Amps)
3
30ºC
2.5
20ºC
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-a-70
Figure A-70
2 oz. Conductors (Vacuum) (5 - 50 Sq-mils)
73
IPC-2152
August 2009
A.6.2.1.3 1⁄2 oz. Conductor Sizing Charts, Vacuum, Imperial (Inch) Units
1/2 oz Vac Poly 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
Current (Amps)
10
10ºC
5ºC
2ºC
1ºC
1
0.1
1
10
100
1000
Cross-Sectional Area (Sq-mils)
IPC-2152-a-71
Figure A-71 1⁄2 oz. Conductors (Vacuum) Log (5 - 700 Sq-mils)
1/2 oz Vac Poly 0.07
30
100ºC
25
75ºC
Current (Amps)
20
60ºC
45ºC
15
30ºC
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
100
200
300
400
500
600
700
800
Cross-Sectional Area (Sq-mils)
IPC-2152-a-72
Figure A-72 ⁄ oz. Conductors (Vacuum) (5 - 700 Sq-mils)
12
74
August 2009
IPC-2152
1/2 oz Vac Poly 0.07
100ºC
5
60ºC
75ºC
45ºC
4.5
30ºC
4
20ºC
Current (Amps)
3.5
3
2.5
10ºC
2
5ºC
1.5
2ºC
1
1ºC
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Cross-Sectional Area (Sq-mils)
IPC-2152-a-73
Figure A-73 1⁄2 oz. Conductors (Vacuum) (5 - 100 Sq-mils)
1/2 oz Vac Poly 0.07
100ºC
75ºC
5
4.5
60ºC
4
45ºC
Current (Amps)
3.5
3
30ºC
2.5
20ºC
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
5
10
15
20
25
30
35
40
45
50
Cross-Sectional Area (Sq-mils)
IPC-2152-a-74
Figure A-74 1⁄2 oz. Conductors (5 - 50 Sq-mils)
75
IPC-2152
August 2009
A.6.2.2 Vacuum/Space Environment Charts in SI (Metric) Units Figure A-75 through Figure A-88 represent charts for
internal and external conductors in vacuum/space environments in SI (Metric) units.
A.6.2.2.1 3 oz. Conductor Sizing Charts, Vacuum, SI (Metric) Units
3 oz Int Vac Poly
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
5ºC
Current (Amps)
10
2ºC
1ºC
1
0.1
0
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
0.001
0.01
0.1
1
0.01
Width (mm)
0.1
1
10
3-oz (0.099 mm thick)
2-oz (0.06 mm thick)
1-oz (0.033 mm thick)
1/2-oz (0.065 mm thick)
1/4-oz (0.00826 mm thick)
100
IPC-2152-a-75
Figure A-75
76
3 oz. Conductors (Vacuum) Log (0.001 - 0.5 Sq-mm)
August 2009
IPC-2152
1/2 oz Vac Poly 0.07
30
100ºC
25
Current (Amps)
75ºC
60ºC
20
45ºC
15
30ºC
20ºC
10
10ºC
5
5ºC
2ºC
1ºC
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
IPC-2152-a-76
Figure A-76
3 oz. Conductors (Vacuum) (0 - 0.5 Sq-mm)
3 oz Int Vac Poly
100ºC
10
9
75ºC
8
60ºC
Current (Amps)
7
45ºC
6
30ºC
5
20ºC
4
3
10ºC
2
5ºC
1
2ºC
1ºC
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-77
Figure A-77
3 oz. Conductors (Vacuum) (0 - 0.1 Sq-mm)
77
IPC-2152
August 2009
3 oz Int Vac Poly
100ºC
5
4.5
75ºC
4
60ºC
Current (Amps)
3.5
45ºC
3
30ºC
2.5
20ºC
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
Cross-Sectional Area (Sq-mm)
Figure A-78
78
3 oz. Conductors (Vacuum) (0 - 0.03 Sq-mm)
0.025
0.03
IPC-2152-a-78
August 2009
IPC-2152
A.6.2.2.2 2 oz. Conductor Sizing Charts, Vacuum, SI (Metric) Units
2 oz Int Vac Poly
100
20ºC
10ºC
5ºC
2ºC
1ºC
Current (Amps)
10
100ºC
75ºC
60ºC
45ºC
30ºC
1
0.1
0.01
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
0.001
0.01
Width (mm)
0.1
1
3-oz (0.099 mm thick)
2-oz (0.06 mm thick)
10
1-oz(0.033 mm thick)
1/2-oz (0.065 mm thick)
1/4-oz (0.00826 mm thick)
100
IPC-2152-a-79
Figure A-79
2 oz. Conductors (Vacuum) Log (0 - 0.5 Sq-mm)
79
IPC-2152
August 2009
2 oz Int Vac Poly
30
100ºC
25
75ºC
Current (Amps)
20
60ºC
45ºC
15
30ºC
20ºC
10
10ºC
5ºC
5
2ºC
1ºC
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
IPC-2152-a-80
Figure A-80
2 oz. Conductors (Vacuum) (0 - 0.5 Sq-mm)
2 oz Int Vac Poly
100ºC
Current (Amps)
10
9
75ºC
8
60ºC
7
45ºC
6
30ºC
5
20ºC
4
10ºC
3
5ºC
2
2ºC
1ºC
1
0
0
0.02
0.04
0.06
0.08
0.1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-81
Figure A-81
80
2 oz. Conductors (Vacuum) (0 - 0.1 Sq-mm)
August 2009
IPC-2152
1/2 oz Vac Poly 0.07
100ºC
5
75ºC
4.5
60ºC
4
45ºC
Current (Amps)
3.5
3
30ºC
2.5
20ºC
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Cross-Sectional Area (Sq-mm)
IPC-2152-a-82
Figure A-82
2 oz. Conductors (Vacuum) (0 - 0.03 Sq-mm)
81
IPC-2152
August 2009
A.6.2.2.3 1⁄2 oz. Conductor Sizing Charts, Vacuum, SI (Metric) Units
1/2 oz Vac Poly 0.07
100
100ºC
75ºC
60ºC
45ºC
30ºC
20ºC
10ºC
5ºC
Current (Amps)
10
2ºC
1ºC
1
0.1
0.01
0.001
0.01
0.1
1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-83
Figure A-83 1⁄2 oz. Conductors (Vacuum) Log (0 - 0.5 Sq-mm)
1/2 oz Vac Poly 0.07
30
100ºC
25
75ºC
60ºC
Current (Amps)
20
45ºC
15
30ºC
20ºC
10
10ºC
5
5ºC
2ºC
1ºC
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Cross-Sectional Area (Sq-mm)
IPC-2152-a-84
Figure A-84 ⁄ oz. Conductors (Vacuum) (0 - 0.5 Sq-mm)
12
82
August 2009
IPC-2152
1/2 oz Vac Poly 0.07
100ºC
10
75ºC
9
60ºC
8
45ºC
Current (Amps)
7
6
30ºC
5
20ºC
4
3
10ºC
2
5ºC
1
2ºC
1ºC
0
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Cross-Sectional Area (Sq-mm)
IPC-2152-a-85
Figure A-85 1⁄2 oz. Conductors (Vacuum) (0 - 0.1 Sq-mm)
1/2 oz Vac Poly 0.07
100ºC
5
75ºC
4.5
60ºC
4
45ºC
Current (Amps)
3.5
3
30ºC
2.5
20ºC
2
10ºC
1.5
5ºC
1
2ºC
1ºC
0.5
0
0
0.005
0.01
0.015
0.02
Cross-Sectional Area (Sq-mm)
0.025
0.03
IPC-2152-a-86
Figure A-86 1⁄2 oz. Conductors (Vacuum) (0 - 0.03 Sq-mm)
83
IPC-2152
August 2009
0.001
0.01
0.01
0.1
1
Width (mm)
0.1
1
3-oz (0.099 mm thick)
2-oz (0.066 mm thick)
10
1-oz (0.033 mm thick)
1/2-oz (0.0165 mm thick)
1/4-oz (0.00826 mm thick)
100
IPC-2152-a-87
Figure A-87
Log width chart
Cross-Sectional Area (Sq-mils)
1
10
100
1000
0.0001
0.001
Width (inch)
0.01
0.1
3-oz (0.0039 in thick)
2-oz (0.0026 in thick)
1
1-oz (0.0013 in thick)
1/2-oz (0.0165 in thick)
1/4-oz (0.000335 in thick)
10
IPC-2152-a-88
Figure A-88
84
Log width chart (inch)
August 2009
IPC-2152
A.7 REFERENCES
[1] NBS (National Bureau of Standards) Report #4283 ‘‘Characterization of Metal-insulator Laminates’’, D.S. Hoynes, May
1, 1956. Commissioned by Navy Bureau of Ships.
A.7.1 The Origin of the First Conductor Sizing Chart Conductor current carrying capacity became an area of interest
when the first single-sided PBs started to be manufactured in the 1950’s. The National Bureau of Standards (NBS) was
funded by the United States Navy to derive guidelines for sizing electrical conductors. The result of this study was the
development of a chart that shows the relationship between conductor cross-sectional area, conductor temperature rise, and
current, as shown in Figure A-89. The comment, ‘‘FOR USE IN DETERMINING CURRENT CARRYING CAPACITY
AND SIZES OF ETCHED COPPER CONDUCTORS FOR VARIOUS TEMPERATURES ABOVE AMBIENT’’ is relevant
to the testing performed and documented in the Reference [1]. The word (Tentative) in Figure A-89 is also relevant to Reference [1], where additional testing had been proposed, although not performed. The comment within Figure A-89 that refers
to a design guide on the preceding page is included for historical purposes only and is not relevant to IPC-2152.
Test data was collected from different size external conductors on two-sided PBs. The conductors consisted of varying
widths and copper thicknesses of 1⁄2 oz., 1 oz., 2 oz. and 3 oz. copper. The PB dielectric materials were phenolic (XXXP)
and epoxy. The PB thicknesses were 0.79 mm [0.0313 in], 1.59 mm [0.0625 in] and 3.18 mm [0.125 in]. Testing was performed following procedures that resulted in finding the conductor temperature rise as a function of current for a specific
cross-sectional area. Figure A-89 is the result of using a best-fit curve through data points that were influenced by all of
these variables. See Figure A-90 for an example of one of the NBS original data sets. These data sets were combined to
create the first external conductor-sizing chart, which is shown in Figure A-89.
As a result of combining conductor heating data influenced by multiple variables into one chart, the temperature rise predicted for a specific current level and conductor size will vary depending on PB size, conductor thickness, material property and environmental conditions.
It was determined from the original testing that:
a)
Current carrying capacity decreased when copper thickness increased for the same cross-sectional area.
b) Current carrying capacity decreased as the PB thickness decreased.
c)
Current carrying capacity increased when the opposite side of the double-sided PBs was copper clad.
Finally, Figure A-91 is presented for comparison with Figure A-89.
85
IPC-2152
August 2009
DESIGN CHART
(TENTATIVE)
FOR USE IN DETERMINING CURRENT CARRYING CAPACITY AND SIZES OF ETCHED COPPER
CONDUCTORS FOR VRIOUS TEMPERATURE RISES ABOVE AMBIENT.
(NOTE: SEE DESIGN GUIDE ON PRECEDING PAGE FOR USE OF THIS CHART).
36
ºC
0ºC 75
ºC
60 ºC
45
C
30º
10
30
25
20
C
20º
Current in Amperes
16
10ºC
12
9
8
7
6
5
4
3
2
1.5
1
.75
.50
.25
.125
Conductor Width in Inches
0
.001
.004
.009
.016
.025
.036
.049
.064
(3 o
.081
.100
z).0
04"
.121
.144
.169
.196
(2
oz
).0
.225
.256
.289
.324
(1
/2
(1
oz
oz
01
00
35
"
67
"
4
16
36
64
100
144
196
7"
).0
).0
.361
.400
02
256
324
400
484
576
676
Cross Section in Sq mils
IPC-2152-a-89
Figure A-89
86
Original NBS Chart
August 2009
IPC-2152
IPC-2152-a-90
Figure A-90
NBS 10 °C Data Curves
87
IPC-2152
August 2009
35.0
C
0ºC 75º 0ºC
6
ºC
45
C
30º
25.0
20.0
.001
C
20º
15.0
Conductor Width in Inches
Current in Amperes
0
10
30.0
C
10º
12.0
10.0
8.0
7.0
6.0
5.0
4.0
.005
.010
.015
.020
.030
.050
.070
(3 o
.100
(2
.150
.200
3.0
.250
2.0
1.5
1.0
.75
.50
.25
.125
0
0
.300
(1
2 oz
(1
/ft 2
).0
oz
/ft 2
).0
00
01
4"
7"
.350
z/ft 2
).00
42"
oz/ 2
ft )
.00
28"
.400
0
1
5
10
20 30
50
70
100
150
200
250 300
400
500
600
700
Cross-Sectional Area (Sq-mils)
1
5
10
20 30
50
70
100
150
200
250
300
400
500
600
700
Conductor Width to Cross-Section Relationship
Cross-Sectional Area (Sq-mils)
External Conductors
17.5
15.0
C
45º
C
º
30
12.5
Current in Amperes
10.0
C
20º
7.5
10ºC
6.0
5.0
4.0
3.5
3.0
2.5
2.0
1.5
1.0
.75
.50
.30
.25
.125
.062
0
0
1
5
10
20 30
50
70
100
150
200
250 300
400
500
600
700
Cross-Sectional Area (Sq-mils)
Internal Conductors
IPC-2152-a-91
Figure A-91
88
Historical IPC Charts
August 2009
IPC-2152
Table A-5 through Table A-7 lists the codes that represent the test vehicles used by the National Bureau of Standards to create the chart in Figure A-89. The tables also include the type of material and PB (core) thickness, copper thickness, additional processing that the test vehicle went through and the test method used to measure the conductor temperature rise.
Table A-5
NBS Data Reference Table
Materials, Processing, and Conditions Used in Determining the Temperature
Rises of Various Etched Conductors (K denotes single clad KK double clad)
Code
Material and Core
Thickness (in.)
Copper Thickness (in.)
Additional
Processing
Test Temp (°C)
Test Method
A
5-7 XXXP 1/16
0.0027 KK
None
50
IR & TC
B
2-7 XXXP 1/16
0.004 K
None
50
IR & TC
C
4-7 XXXP 1/16
0.00135 K
None
50
IR
D
4-10 Epoxy 1/16
0.00135 K
None
50
IR & TC
E
5-7 XXXP 1/16
0.0027 K
None
60
IR & TC
F
2-7 XXXP 1/16
0.0027 K
None
60
IR
G
4-7 XXXP 1/16
0.00135 KK
None
60
IR
H
5-7 XXXP 1/16
0.0027 KK
None
25
IR
I
2-7 XXXP 1/16
0.004 K
None
25
IR & TC
J
5-10 Epoxy 1/16
0.0027 K
None
25
IR
K
4-7 XXXP 1/16
0.00135 KK
None
25
IR
Table A-6
NBS Data Reference Table (Cont’d)
(K denotes single clad KK double clad)
L
5-7 XXXP 1/16
0.00135 K
None
25
IR
M
2-7 XXXP 1/16
0.00135 K
None
25
TC
N
4-7 XXXP 1/16
0.0067 K
None
25
IR
O
4-10 Epoxy 1/16
0.00135 KK
None
25
IR
P
5-7 XXXP 1/16
0.00135 K
None
25
IR
Q
2-7 XXXP 1/16
0.00135 K
None
25
IR
R
4-7 XXXP 1/16
0.0027 K
None
25
IR
S
5-7 XXXP 1/16
0.00135 K
None
25
IR
T
2-7 XXXP 1/16
0.0027 K
None
25
IR
U
5-10 Epoxy 1/16
0.00135 K
None
25
IR
Table A-7
NBS Data Reference Table (Cont’d)
(K denotes single clad KK double clad)
V
2-7 XXXP 1/16
0.0027 K
Dip soldered 10 sec 250 °C
25
IR
W
10-7 XXXP 1/16
0.00135 K
Dip soldered 10 sec 250 °C
25
IR
X
5-10 Epoxy 1/16
0.0027 K
Dip soldered and coated with 0.005 epoxy resin
25
IR & TC
Y
4-7 XXXP 1/16
0.00135 K
Dip soldered 10 sec 250 °C
25
IR
Z
2-7 XXXP 1/16
0.0027 K
Dip soldered 10 sec 250 °C
25
TC
1
5-7 XXXP 1/16
0.00135
Core removed conductor in free air (CRFAIR)
25
IR
2
6-16 G-5
0.00135
(CRFAIR)
25
IR
3
2-7 XXXP 1/16
0.00135
(CRFAIR)
25
IR
4
5-7 XXXP 1/16
0.0027
(CRFAIR)
25
IR
5
2-7 XXXP 1/16
0.0027
(CRFAIR)
25
IR
6
2-7 XXXP 1/16
0.0027
(CRFAIR)
25
IR
7
4-10 Epoxy
0.00135
(CRFAIR)
25
IR
89
IPC-2152
August 2009
This Page Intentionally Left Blank
90
ANSI/IPC-T-50 Terms and Definitions for
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