"AlSiC-Based Hybrid
Composite Tool Kit"
By Richard W. Adams
and Mark A. Occhionero
Ceramics Process Systems
111 South Worcester St
Chartley MA 02712-0338
www.alsic.com
New England IMAPS 31 Annual Symposium
Thursday May 6, 2004
"AlSiC-Based Hybrid Composite Tool Kit"
• Abstract: AlSiC and multi-component structures provide unique
thermal management electronic packaging solutions for
microwave, microelectronics, power electronics, and
optoelectronics that result in improved product reliability. This
paper reviews volume AlSiC manufacturing applications today,
and then describes examples of a wide range of possibilities for
multi-component, multi-functional thermal management
structures.
AlSiC Packaging for Electronics Thermal Management
- Basic Parameters
• Controlled Thermal Expansion
– Engineered CTE values - for component and assembly
compatibility = reliability
– Engineered solutions can create typical CTE values 7-12 ppm/°C
• Thermal Dissipation
– High isotropic thermal conductivity, typical = 200 W/mK
• Lightweight
– 3 g/cm3
• Cost Effective Manufacturing Capability - net shape cast
CPS AlSiC Fabrication - Defines Properties and Design
•
SiC to Al-metal ratio defines thermal expansion
– 1st - SiC preform with controlled and variable volume content
– 2nd - Infiltrate with Al-metal to form the AlSiC composite
•
Thermal conductivity determined by components
– Electronic Grade SiC 230 - 260 W/mK
– A356.2 Casting Alloy 160 W/mK
– Little influence of ratio of 2 components
•
net shape forming
– preform is ~ smaller than final part
– infiltration tool = final dimensions
– eliminates costly machining
SiC preform
AlSiC product
injection molded
infiltration casting
AlSiC - Metal Matrix Composite Material
CPS AlSiC Instantaneous CTE
15
SiC
Instantaneous CTE (ppm/°C)
14
~37 vol% SiC
AlSiC-12
13
12
~55 vol% SiC
AlSiC-10
11
10
~63 vol% SiC
9
8
AlSiC-9
7
6
SiC particles uniformly distributed
in continuous Al-matrix
5
25
50
75
100
125
150
175
200
Temperature (°C)
See www.alsic.com
AlSiC Tools
• Marry Properties to Product Design
• Design Functionality
– Basic AlSiC
• lids
• baseplates
• package system structures
– AlSiC + Concurrent IntegrationTM
• Cooling Tubes - active fluid
• HOPG / Diamond -
passive transfer
• Dielectric Ceramic Inserts - Ω isolation
Basic AlSiC Design
•
•
Pick compatible AlSiC CTE
–
Seal rings
–
Substrates
–
Devices
Design rules for AlSiC casting
–
Draft Angles
–
Thicknesses
–
Radii
–
Al-Rich Areas for conventional
machining
See www.alsic.com
Basic AlSiC - lids
• Simple to Complex Geometries
•Applications:
•Microprocessor Lids
•DSP
•Flip Chip Lids
•Optical Lids
•Volumes
•100 pcs - 40K/week
•Price (Volume/Complexity)
• $ 2 - $ 5 in volumes of
~100K/yr
Basic AlSiC - lids
• Complex Geometries
•Product is net-shape fabricated no machining
•multiple pedestals
•angled features
•radial alignment features
•septums and walls
•lower cost than machined
Aluminum alternative
Basic AlSiC - Baseplates
•
Compatible CTE = unlimited
thermal cycling of package
– AlN soldered to AlSiC
•
Thomas Schuetze, Herman Berg, Oliver
Schilling “The new 6.5kV IGBT module: a
reliable device for medium voltage
applications”, PCIM September 2001
Design
– Dome Shape - Side 1
• Compressing a dome shape
against flat cold plate
maximizes heat transfer
– Flat - Side 2
• Attachment of “flat” substrates
convex bow cooler plate surface
flat dielectric substrate surface
Concurrent IntegrationTM -High Density Interconnect (HDI) for
GaAs Microwave Transmit/Receive Packages
• Dielectric Feedthrus
First, dense dielectric ceramic
ferrules are inserted into the
QuickCastTM infiltration tooling
along with the SiC preform.
Then, the Al-metal, that infiltrates
the SiC preform to form the AlSiC
composite, hermetically bonds and
fills the ferrules to form coaxial
feedthrus. This process is termed
Concurrent IntegrationTM.
Concurrent IntegrationTM - AlSiC LED Submount
• Alloy Metal Inserts
•Product Features:
•multiple pedestals
•angled features
•partially machined to expose Alloy
49 pads for assembly
•Alloy 49 bonded direct to Al phase
of AlSiC
Alloy 49 pad
Concurrent IntegrationTM - Optoelectronic AlSiC TE
Cooler Substrate with HOPG
• High Thermal Conductivity Insert
Heat source surface
•
Product Features:
– Pyrolytic Graphite (PG) compressively
encapsulated within AlSiC
– Thermal conductivity 1300 W/mK
– PG located near heat source/TE
cooler position.
1350 W/mK
• Selective use of costly material
AlSiC
HOPG
AlSiC
1300 W/mK
1350 W/mK
AlSiC laser diode TEC substrate system showing TEC
mount area (top) and the cross section showing the
HOPG insert in the AlSiC composite (bottom).
Concurrent IntegrationTM - Liquid Flow Thru Cooling
• Cooling Tube or Heat Exchanger
Product Features:
• Tube intimate within AlSiC casting
–
–
–
•
•
SiC overmolded onto tube
Direct bond AlSiC to tube
Maximize heat transfer AlSiC to tube
Low cost one step assembly
CPS Patented process
Metallurgical Bonding AlSiC to AlSiC
•
Friction Stir Welding
•Bonding of Engineered Al-Rich
Areas within AlSiC casting
•Al Solder Bonding Processes
•Various commercially available
•Desired Al Skin Present on
AlSiC
Heat sink and housing are joined by
Friction Stir Welding.
TOP
BASE
QuickCastTM High Pressure Precision Aluminum Casting
•
Aluminum-only precision casting
– Tolerances in the +/-0.003” Range
– Low cost tooling
– Rapid product introduction and
moderate production rate
•
Option for Concurrent IntegrationTM
– Diamond, PG, etc inserts
High Output LED light housing
• RV, Boats, Theater, Safety Lighting
Summary "AlSiC-Based Hybrid Composite Tool Kit"
• Basic AlSiC Properties coupled with Concurrent IntegrationTM
– AlSiC = Engineered CTE, Thermal Conductivity, Lightweight
– CPS AlSiC =
• Shape Complexity and Tight Tolerance - net shape
• Attractive Value Proposition for many (growing number) of Applications
• Concurrent IntegrationTM Presents Thermal Package Design
Options - limited only to your imagination
– AlN, ZTA, Al2O3, Si3N4 Substrates/Ferrules, etc.
– Stainless steel, alloy 49, Titanium inserts
– Tubes, Heat exchangers, welded pin fin coolers
– High Thermal Conductivity Diamond, PG
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