TO-263S heat dissipation

[reyntjensm]

Hello everyone,

I'm designing a mosfet PWM device with a rather high current. According to my LTspice simulation the mosfet has an average power dissipation of 20W. The mosfet had a TO-263S package ( https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/mosfet/r6020pnjfratl-e.pdf ). What would be the best setup/design to get rid of this heat? I have two of those mosfets next to each other, so the heat sink should be able to dissipate 40W. Can i just connect the heat sink to the top of the case or are there better alternatives?

[thm_w]

The heatsink can be connected on top of the case, onto the copper plane on the top of the PCB, or on the copper plane on the bottom of the PCB. In the last case you'd use thermal vias to transfer heat through the board.

https://www.infineon.com/dgdl/smdpack.pdf?fileId=db3a304330f6860601311905ea1d4599

edit: looks like you crossposted it here https://www.eevblog.com/forum/projects/to-263s-heat-dissipation-261614/msg0/