curamik® COOLING SOLUTIONS
Integrated DBC Coolers
curamik® CoolPower Plus, curamik® CoolPerformance Plus
Design Rules Version 02/2015
Content
1. General construction of integrated DBC coolers ............. 11
5. Performance................................................................... 10
2. Cooling direction and active area
6. Physical properties and recommendations
2.1. Serial cooling.................................................................... 03
6.1. Properties.......................................................................... 11
2.2. Parallel cooling................................................................ 03
6.1.1. Material.......................................................................... 11
6.1.2. Temperature resitance................................................... 11
3. Cooler outline
6.1.3. Pressure resitance......................................................... 11
3.1. Geometric properties....................................................... 04
6.1.4. Thermal conductivity..................................................... 11
3.1.1. Length, width and active cooled area........................... 04
6.1.5. Electrical resistivity (ceramic)....................................... 11
3.1.2. Wall thickness............................................................... 04
6.1.6. Dielectric strength (ceramic)......................................... 11
3.1.3. Mounting holes............................................................. 05
6.1.7. Electrical conductivity (copper).................................... 11
3.1.4. Outside dimension tolerances...................................... 05
6.2. Recommendations...........................................................12
3.1.5. Thickness....................................................................... 06
6.2.1. Cooling fluid...................................................................12
3.1.6. Thickness tolerance...................................................... 06
6.2.2. Flow velocity..................................................................12
3.2. Flatness........................................................................... 07
6.2.3. Particle size...................................................................12
3.3. Inlet & Outlet................................................................... 07
6.2.4. Cooling system..............................................................12
3.3.1. O-Ring seats.................................................................. 07
3.3.2. Copper fittings (inner thread)...................................... 07
3.4. Holes................................................................................ 08
4. Surface options
4.1. Surface roughness........................................................... 09
4.2. Plating.............................................................................. 09
1. General construction of integrated DBC coolers
1
2
3
4
5
6
7
Picture 1 Example of cooler construction (see also table)
1
Fittings for in- and outlet (optional)
For connection of hoses / tubes
2
Bottom DBC
DBC substrate with holes for in-/ outlet
3
Sealing layer
Structured layer forming the inlet and outlet
4
Manifold layers (optional)
Structured layers to distribute the cooling liquid
5
Separation layer (optional)
Structured layer to guide the cooling liquid for more uniform cooling of active side
6
Active cooling layers
Structured layers for liquid cooling
7
Top DBC
DBC substrate for assembly of components
2. Cooling direction and active area
2.1. Serial cooling
2.2. Parallel cooling
Cooling direction from the inlet to outlet side
Cooling direction crosswise to inlet and outlet
Outlet
flow
Inlet
Picture 2 Serial cooling
dire
ctio
n
Outlet
flo
w
Inlet
di
re
ct
io
n
Picture 3 Parallel cooling
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3. Cooler outline
3.1. Geometric properties
3.1.1. Length, width and active cooled area
Max. outer dimension [mm]
178 x 127
Max. active cooled area [mm]
175 x 124
Note Mounting holes (see 3.1.3) are required for all DBC coolers.
Quantity of mounting holes depends on the size of the cooler (minimum 2; maximum 4 necessary for production).
mounting hole
Active cooled area
wall thickness
Picture 4 Length, width and active cooled area with mounting holes
3.1.2. Wall thickness
Minimum wall thickness (around active cooling area)
Depending on cooler size:
Outline ≤ 60 x 80 mm (w x l)
wall thickness ≥ 0.8 mm
Outline > 60 x 80 mm (w x l)
wall thickness ≥ 1.5 mm
wall thickness
DBC
pullback
Picture 5 Active cooled area and wall thickness (cross section)
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curamik® COOLING SOLUTIONS I Integrated DBC Coolers I Design Rules I Version 02/2015
3.1.3. Mounting holes
Typical diameter = 4.1 mm
Note Other diameter on request.
3.1.4. Outside dimension tolerances
Tolerance of
outside dimension
+ 0.2 mm / -0.05 mm
Note Reference is top (active side) or bottom DBC (TBD).
Possible mismatch of single layers ≤ 0.15 mm
Bottom DBC 0.4 mm smaller in length and width than top DBC = offset
mismatch
offset
Picture 6 Mismatch copper layers and offset top to bottom DBC
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3.1.5. Thickness
The thickness of the cooler depends on the number of active cooling layers.
Using a separation layer will increase the thickness of a cooler compared to
a cooler with no separation layer.
Recommended maximum number of active cooling layers
8 – 10
Minimum number of active cooling layers
2
Maximum number of copper layers
30
Available copper layer thicknesses in mm*
0.2 / 0.25 / 0.3 / 0.4 / 0.5 / 0.6
Available ceramic thickness AlN in mm
0.5 / 0.63
Available ceramic thickness HPS** in mm
0.32
Maximum copper thickness on DBC in mm
0.3
Maximum total thickness in mm
10
* Standard thickness of active cooling layers = 0.3 mm (other thickness on request)
** The HPS products are subject to patent restrictions in some countries.
Based on zirconia toughened alumina (ZTA).
Note Other ceramic thickness and more copper layers on request.
Different thicknesses of copper layers can be combined.
Symmetrical DBC combination top to bottom is mandatory due to CTE mismatch/ requirements.
thickness
Picture 7 Cooler thickness
3.1.6. Thickness tolerance
Non machined cooler
Tolerance is depending on quantity
and thickness of copper layers;
can be defined after first sample
evaluation
Top side diamond turned cooler
± 50 µm
Note In case of machined surface the cooler can either be machined to a total
thickness requirement or to a remaining copper thickness on DBC surface.
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curamik® COOLING SOLUTIONS I Integrated DBC Coolers I Design Rules I Version 02/2015
3.2. Flatness
Requested flatness of coolers cannot be guaranteed in advance due to specific influences of the inner design
and circuit structure. Flatness (not 100% inspected) can only be specified after design definition and sample
delivery with initial sample test report.
3.3. Inlet & outlet
3.3.1. O-Ring seat
bottom DBC
sealing layer
Picture 8 O-Ring seat
Note O-Ring seat layer thickness = 0.6 mm recommended to avoid deformation of this layer.
Open cross section of inlet and outlet should be bigger than open cross section of cooling structure to avoid
high pressure drop in in- & outlet → open cross section of cooling structure approx. 50%.
3.3.2. Copper fittings
Picture 9 Fitting with G 1/8 inner thread
Note Fitting seat layer thickness = 0.6 mm recommended to avoid deformation of this layer.
Open cross section of inlet and outlet should be bigger than open cross section of cooling structure to avoid
high pressure drop in in- & outlet → open cross section of cooling structure approx. 50%.
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x
y
Picture 10 Copper fittings tolerance
Note Tolerance of fittings X / Y ± 0.4 mm.
Other fitting dimensions and geometries on request.
3.4. Holes
Min. hole diameter in ceramic ≥ 1 mm
Min. hole diameter in copper ≥ 1mm
Hole tolerance
Through hole
(hole in ceramic smaller than in copper layers)
± 0.05 mm
Machined hole (copper)
(hole in inner copper layers smaller than in ceramic)
on request (e.g. tight fit hole)
Ø hole
wall thickness
offset
Picture 11 Through hole (hole in ceramic)
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curamik® COOLING SOLUTIONS I Integrated DBC Coolers I Design Rules I Version 02/2015
Ø hole
Picture 12 Machined hole (e.g. tight fit hole)
Note Active cooling around holes will be reduced by wall thickness and copper pullback.
4. Surface options
4.1. Surface roughness
a) Standard: Rmax = 50 µm; Ra ≤ 4 µm; Rz ≤ 16 µm
b) Diamond turned surface: Rmax ≤ 10 µm; Ra ≤ 0,8 µm; Rz ≤ 5 µm *
*Depending on surface plating lower values possible
4.2. Plating
Electroless Ni
3 – 7 µm (8% ± 2% P)
Electroless Ag
0.1 – 0.6 µm
Electroless NiAu
Ni: 3 – 7 µm (8% ± 2% P)
Au: 0.03 – 0.13 µm
Note Inside plating is not possible. No plating in tight fit holes.
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5. Performance
Pressure drop and thermal resistance
(Example for AlN 0.63 mm and HPS 0.32 mm cooler with 10 active
cooling layers 0.3 mm thickness & standard cooling structure)
Pressure Drop & Rth(A)
0.6
450
0.54
400
0.48
350
0.42
300
0.36
250
0.3
200
0.24
150
0.18
100
0.12
50
0.06
0
0
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
Flowrate [l/min]
Pressure Drop
Rth(A) AIN 0.63 mm
Rth(A) HPS 0,32 mm
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curamik® COOLING SOLUTIONS I Integrated DBC Coolers I Design Rules I Version 02/2015
8.00
Rth(A) [K*cm2/W]
Pressure Drop [mbar]
500
6. Physical properties* and recommendations
*values from literature
6.1. Properties
6.1.1. Material
Insulation material
AIN
HPS
Copper
OFHC
6.1.2. Temperature resistance
Max. 400°C
6.1.3. Pressure resistance
Max. 5 bar (no leakage, deformation possible depending on design)
6.1.4. Thermal conductivity
HPS
26 W/mK @ 20 °C
AIN
170 W/mK @ 20 °C
6.1.5. Electrical resistivity (ceramic)
Electrical resistivity of ceramic
>1014 Ωcm @ 20 °C
6.1.6. Dielectric strength (ceramic)
Dielectric strength (DC voltage) of ceramic
>20kV/mm
6.1.7. Electrical Conductivity (copper)
Electrical conductivity of cooper surface
58 x 106 S/m @ 20 °C
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6.2. Recommendations
6.2.1. Cooling fluid
Tap water (no DI-water!), no corrosive fluids
6.2.2. Flow Velocity
< 2 m/s (critical value for flow corrosion; depending on water temperature this value can be lower)
6.2.3. Particle size
≤ 200 µm (depending on inner cooler design smaller)
6.2.4. Cooling system
Do not use materials which build a galvanic cell with copper (e.g. Al, Zinc, brass), preferably V4A-alloy without sulfur.
Use synthetic materials (tubes, gaskets, etc.) with lower diffusivity of oxygen and without soluble additives.
For layout design and further information on DBC refer to Rogers Germany GmbH DBC-Design Rules.
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curamik® COOLING SOLUTIONS I Integrated DBC Coolers I Design Rules I Version 02/2015
The information contained in this document is intended to assist you in designing with Rogers’ Power Electronics Solutions
Materials. It is not intended to and does not create any warranties, express or implied, including any warranty of merchantability or fitness for a particular purpose or that the results shown in this document will be achieved by a user for a particular
purpose. The user should determine the suitability of curamik® products for each application. The Rogers logo, the curamik
logo and curamik are licensed trademarks of Rogers Corporation.
© 2015 Rogers Corporation. All rights reserved.
This document is not subject of updating.
Version 01/2015 issued in January 2015.
Issued by Nico Kuhn and Paul Ren
Approved by Tomas Block and Stephan Schrenker
curamik® COOLING SOLUTIONS I Integrated DBC Coolers I Design Rules I Version 02/2015
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Rogers Germany GmbH
Am Stadtwald 2
92676 Eschenbach
Germany
Phone +49 9645 92 22 0
Fax +49 9645 92 22 22
www.rogerscorp.com/pes