RF Power Transistor MountingNovember 7th Fact-of-the-Day
Contrary to popular belief, the area around and under RF power transistor mounting bolt heads conduct the bulk of the heat way from most types of RF power transistors rather than the area directly under the silicon chip. Furthermore, contrary to what might be expected intuitively, increasing mounting bolt torque beyond manufacturer's specifications often actually decreases thermal conductivity. The most important way to increase thermal conductivity is to apply a 'very thin' layer of heatsink compound between a transistor and a heatsink. However, as with excessive mounting bolt torque, excessive heatsink compound thickness actually decreases thermal conductivity. ©2004 Martek International All rights reserved.
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