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User’s Guide
HB2637L-EVK-301
© 2022 ROHM Co., Ltd.
No. 65UG002E Rev.001
Apr. 2022
3.7 Mounting Heatsink
The evaluation board is mainly thought for electrical characterization using double pulse tests. For these tests, a heatsink is not
necessary since the power device is not continuously stressed. However, if measurements in continuous power operation are
needed then depending on output power requirement a heatsink must be mounted.
On this board, underneath the drain pad of each SiC MOSFET, a total of 370 vias that are filled and capped according to IPC
4761 Typ VII are provided. All the four layers (top, inner layer 1, inner layer 2 and bottom) are connected through and through with
these filled and capped vias. On the bottom layer, the copper is exposed so that a heatsink with a thermal interface material can
be mounted. Figure 11 shows the bottom side of the PCB with exposed copper and filled/capped vias.
The recommended thermal interface sheets are SIL pad 2000 from Henkel adhesives or dual side stickable WL 404 11 from
Fischer Elektronik. The heatsink LAM 5 100 5 from Fischer Elekronik is recommended. In order to mount this heatsink, four
mounting holes as shown in Figure 11 are provided. This heatsink has to be mounted underneath the board and M3 screws can
be used to secure it on to the board. The heatsink and the thermal interface must be mounted in such a way that air gaps between
the board – thermal interface material – heatsink are avoided. The fan for heatsink requires 5V and the onboard available 5V
supply from pin 3 of connector CO2 can be used for this purpose.
Figure 11: Board bottom view with exposed copper and filled/capped vias (top left), thermal interface material with heatsink (top
right), Mounting holes for heatsink (bottom left), evaluation board mounted with heatsink (bottom right)
Exposed pad on the bottom layer with filled
and caped vias underneath MOSFETs
LAM 5 100 5 - Heatsink
Mounting holes for heatsink
