[Amps] FET cases / heat sink

[Scott, Christopher]

I know that Manfred and others on this list have advanced thermodynamics knowledge - and hope to explore a curiosity of mine regarding high power amplifiers with the current 48 volt big fets.

There is prevalent thought that unless one can significantly derate device power handling, bolted device to copper heat spreader connections are  quite inferior - soldering is best.  The device case to copper connection seems the weakest link.

Why don't the manufacturers add another $3.00 worth of copper to the case size (and mass) to better spread the heat over more area (and slow the thermal time constant)?

Wouldn't this greatly improve the functioning?  Wouldn't bolted mounting then work better?

Chris Scott

W4NEQ