Soldering an LDMOS FET onto/into a copper spreader is not difficult.
W6PQL has a video of the process on his site. A heating plate is used to
bring the copper spreader up to temperature.
Once soldered there is no requirement to re-tighten mounting hardware
after so many hours of operation nor is there the possibility of
snapping a screw off in the spreader or God forbid cracking the device
with too much torque.
On 1/2/2017 12:03 PM, Scott, Christopher wrote:
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
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R. Kevin Stover
AC0H
ARRL
FISTS #11993
SKCC #215
NAQCC #3441
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