I need some help with a thermal question... I am trying to design an aluminium die casting. It is for an enclosure but will have a PCB screwed to its inside face. The outside face must act as a heatsink. I have two questions: 1) If I need to dissipate 20W of heat from that PCB, what should the heatsink â€œfinâ€ dimensions be like (thickness ad height), and what should their spacing be? I need to ensure optimal performance, but donâ€™t know how to best to design a heatsink. Is there a standard formula or standard rules for designing such a thing? 2) Secondly, I have seen heatsinks that have â€œpinsâ€ instead of â€œfinsâ€. How much better is the performance of pins compared to fins? I presume pins are better because they have more surface area? How could I calculate the geometry of the pins to ensure optimal performance? Any help appreciated.