Hi John,
They do or at least they used to. When I was a kid I built lots of stuff
with TTL and there were some ICs that came in purple, others in blue.
Then there were quad opamps that came in Hunter green. That's not a
joke. The green ones looked the best.
Just make sure there is no beryllium in them. Its oxide can lop some
years off of your lifetime and that of those around you.
Good point. I was tempted to buy a bunch of custom-sliced BeO things a
while back; it has the best thermal conductivity/dielectric constant
ratio of anything except diamond. People will still cheerfully slice
the stuff to your dims and sell it to you. Chickened out, what with
the hazard to everybody, and used AlN, which is almost as good.
I did soak a slice of AlN halfway in a cup of water for a couple of
days, having read that moisture can decompose it into AlO2 and
ammonia, or something. Didn't seem to affect it.
John