If anyone requires someone to assist in REALLY getting "nutty" about
thermal control/dissipation on electronic components, I'd be happy to
oblige from my experience.
I have had some fairly extensive hand-on experience. Once upon a time,
I invented Arctic Silver thermal compound and adhesive. Before, during,
and after that time I spent thousands of hours working on custom thermal
control solutions.
It's.... an addiction.
73,
Clay KY5G
On 10/27/2017 6:00 PM, Don Wilhelm wrote:
Bill is entirely correct.
Once in my prior career, I did a study of Mean Time Between Failure
for IC circuits (same applies to transistors). That study had to
consider the case temperature of the IC (or transistor) with respect
to the junction temperature.
The specification for the IC or transistor package will include a
thermal resistance parameter, which must be considered to obtain the
maximum temperature for the case of the device.
Bill's comment about the screw tightness is entirely correct - the
heat of the device case must be transferred to the heatsink in an
efficient manner.
73,
Don W3FPR
On 10/27/2017 6:07 PM, Nr4c wrote:
Yes. But I believe that is Junction temperature, not case on heatsink
temp. Remember the case bottom is heatsink for those. Make sure
screws are tight.
Sent from my iPhone
...nr4c. bill
On Oct 27, 2017, at 12:19 PM, N2TK, Tony <[email protected]> wrote:
50C is not hot for a transistor. Commercial transistors are usually
speced to 85C. JANS (space) transistors are speced to 125C and
actually baked without bias for 320 hours at 200C. The hFE is
measured before and after to check for change.
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