Hi Steve
-Yes ceramic is an excellent conductor of heat so your profiling will be
different, delta T is less of a concern for example, but you already deduced
that..
So far as panels and individual circuits are concerned you should be able to
get your panels scribed (analogous to scoring) so they will snap apart after
soldering. Alternatively irregular shaped parts can be profiled leaving only
retaining ligaments so they can be popped out. Maybe a combination can be
done. If you have a decent laser house they will help you with an optimum
design for this, its standard stuff for them.
Profiling is expensive so if you can get scribed parts its much cheaper,
Contact me off-line if you like on this.

Things that people tend to forget
- Ceramic is extremely abrasive and can be sharp edged so if you are
handling any significant volumes you will get fixtures wear, need a little
care when handling
- Ceramic does not flex or bounce too well when dropped.
- Solder joints may be duller so your inspection criteria needs to be
adjusted
- Depending on the dielectrics and so forth you may have some problems if
you use machine vision, ceramic is pure white when not coated.
- Depending on the complexity of the circuitry you may be registering to
edges rather than fixture holes or fiducials.

Mike Fenner
Indium Corporation of Europe
 T: + 44 1908 580 400
 F: + 44 1908 580 411
M: + 44 7810 526 317

  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen R. Gregory
  Sent: Saturday, August 18, 2001 12:57 AM
  To: [log in to unmask]
  Subject: [TN] Assemblies using ceramic substrates...


  Hey all,

  This message is going out Friday night, so I know I won't hear much until
  next week. But anyways, we may be getting some work for an assembly that
is
  on a 2" X  2" ceramic substrate...double sided SMT by the way...

  I know that things are going to be different than the standard fiberglass
  substrate assemblies, IE: more heat for reflow, ect....but is there
anything
  else that I should watch out for?

  Did some ceramic substrate stuff a while back at a past employer, but it
was
  single side stuff and didn't really present too much of a problem..

  I was asked if we could put them in a panel, and as far as I know, you
don't
  want to do that unless you have some very specialized singulation
equipment
  to singulate each assembly. I thought I would get some workpiece fixturing
  and leave them in their 2" X  2"  size...

  Sorry if I'm asking dumb questions, but as once said; "The only dumb
question
  is the one that's not asked..."

  Thanks, and I hope ya'll had a good weekend...

  -Steve Gregory-