What's wrong with heatsinking SMPS SMD FETs by having them on a PCB, with thermal vias going through to bottom copper pour...then 0.05mm thin thermal/insulator pad....then that PCB screwed to a metal heatsink/plate?
...Why instead, do people put the SMD FETs on the bottom side of the PCB, then gouge out a divet in the metal plate for the said FETs, then gap-pad the SMD FET tops to the metal plate?