On Fri, 13 Apr 2018 08:25:20 -0700 (PDT), "
wrote:
Silicon pads. No thinking involved. No grease. No smear. Why not?
W/m*K
Diamond 1000
c-BN 740 (Cubic Boron Nitride)
h-BN 600 (Hexagonal Boron Nitride)
Silver 406
Copper 385
Gold 314
AlN 285 (aluminum nitride ceramic)
Aluminum 205
Graphite 200
Carbon 150
SiC 120
Brass 109
Indium 86
ZnO 50 (zinc oxide)
Al2O3 25 (aluminum oxide ceramic)
Pastes 4.0
Sil Pad 2000 3.5
Circuit Works 1.84
Dow Corning 340 0.67
Sil Pad 2000, which is one of the better silicon impregnated pads, has
a fairly lousy thermal conductivity. The big advantage is that they
don't use thermal goo:
http://www.henkel-adhesives.com/product-search-1554.htm?nodeid=8806349996033
For non-critical applications, such as those encountered by most of
those in this newsgroup, they're just fine. There are ways to install
them incorrectly. If they have a problem, it's that performance
varies with the amount of pressure applied.
25 posts on the quantity of angels and pinheads involved. What a waste.
Really? I got most of my experience with thermal management at a
company that made various RF power products. I think the biggest was
a 2-30MHz 1000 watt PEP power amplifier. To do that with BJT devices
required careful balancing of the devices used in Class AB, which
included careful mechanical balancing. To remain competitive, the
power products had to be better than the competition, while still
meeting FCC IMD specifications and without faking the numbers. The
competitive edge turned out to be the way heat was removed from the
devices, which was my headache. I had to go back to basics because
most of the applications engineers working for the heatsink and power
device companies were more than happy to make their life easier by
accepting mediocre performance. To get what I wanted, I had to start
with basics, and work my way up, which soon demonstrated that much of
the "no thinking" methods, and understandings of how things worked,
were wrong. I don't think it was a waste, but you might if you don't
have similar problems to deal with. Should that happen, be advised
that I derive considerable sadistic enjoyment watching others reinvent
the wheel.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558