Dave D wrote:
wrote in message
ups.com...

This is almost always a grease made of silicone oil and zinc oxide
powder, and some is thick enough to hold the parts together firmly to
require tools to separate them. Don't substitute it with a heatsink
grease containing silver powder, commonly sold for computer CPU
cooling, in case there's high voltage (silver powder is also very
messy).

Shouldn't be an issue with the voltages one would expect to see in a
transistor amp. Cheap white compound will dry out over time and lose its
effectiveness, whereas something like arctic silver shouldn't. I wouldn't
necessarily recommend silver loaded compound mind, but I see no reason not
to use it for this kind of job. It's possible in this case that the
transistor is directly mounted anyway, ie without an insulating pad.

I have a Leach audio amplifier built in the 1970s, and a few years ago
its Radio Shack or GC silicone grease hadn't dried out. So I wouldn't
worry about this, and I don't see why Arctic Silver would be more
resistant to drying out (it may use ester instead of silicone grease).