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EPC90132
EPC – POWER CONVERSION TECHNOLOGY LEADER |
| ©2021 |
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Components to remove
prior
to Heat-spreader attach
Spacers for heat-spreader
attach
M2 screws (x3)
20 mm
9.2 mm
16.7 mm
Heat-spreader
Insulator
PCB
assembly
SMD spacer (x3)
eGaN FETs (x2)
TIM
Figure 10: Details for attaching a heatsink to the EPC90132 board.
(a) 3D perspective, (b) top view details.
THERMAL CONSIDERATIONS
The EPC90132 is intended for bench evaluation
with low ambient temperature and convection
cooling. The addition of a heat-spreader or heatsink
and forced air cooling can significantly increase
the current rating of these devices, but care must
be taken to not exceed the absolute maximum die
temperature of 150°C.
The EPC90132 board is equipped with three
mechanical spacers that can be used to easily
attach a heat-spreader or heatsink as shown in
figure 10 (a), and only requires a thermal interface
material (TIM), a custom shape heat-spreader/
heatsink, and screws. Prior to attaching a heat-
spreader, any component exceeding 1 mm in
thickness under the heat-spreader area will need
to be removed from the board as shown in figure
10 (b).
When assembling the heatsink, it may
be necessary add a thin insulation layer for
components with expose conductors such as
capacitors and resistors
.
The choice of TIM needs to consider the following
characteristics:
• Mechanical compliance
– The TIM becomes
compressed during heatsink attached and exerts
a force on the FETs. A maximum compression of
2:1 is recommended for maximum thermal perfor-
mance and to constrain the mechanical force that
maximizes thermal mechanical reliability.
• Electrical insulation
– The backside of the eGaN
FETs are substrate that are connected to source
and the upper FET will thus be connected to the
switch-node. The TIM must therefore provide
insulation to prevent short-circuiting the upper
FET to the ground.
• Thermal performance
– The choice of thermal
material will affect the thermal performance.
Higher thermal conductivity materials will result in
higher thermal performance.
EPC recommends t-Global P/N: TG-X 500 µm for
the thermal interface material.
The mechanical spacers will accept M2 x 0.4 mm
thread screws.
NOTE
. The EPC90132 development board does not have
any current or thermal protection on board. For more
information regarding the thermal performance of EPC
eGaN FETs, please consult:
D. Reusch and J. Glaser,
a supplement to GaN Transistors for Efficient
First Edition, Power Conversion
Publications, 2015.
(a)
(b)
