On Thu, 06 Oct 2005 19:28:54 -0700, Jim Thompson
wrote:

On Thu, 6 Oct 2005 19:35:36 -0500, "Ron H" wrote:

The 3M conductive adhesives like the 9703 work well. Not sure how they do it
but it conducts in the Z axis ( thru the adhesive ) but not accross the
surface direction ( X & Y axis ). It's a pressure sensitive transfer
adhesive ( tape that you stick on then peel off the paper carrier leaving
the adhesive behind)

X-Y axis Insulation Resistance = 3.4 x 10 to the 14th Ohms/square
Z axis Contact Resistance = 1.25 milliOhm-in2

Pretty neat stuff!

Ron H.


Sounds VERY interesting! I have some clients that need to mount
components that can't stand the heat of soldering. The only problem
might be "tenacity"... how much "shake, rattle and roll" can it take?

...Jim Thompson

Conductive adhesives have been discussed in Advanced Packaging
magazine (IIRC, might have been another trade mag) and the main
problems preventing widespread replacement of solder are not adhesion
but high initial resistance (not suitable for the current required by
large processors etc), and worse, gradual increase in resistance over
time especially at higher temperatures and humidities due to slow
oxidation of the conductors as water vapor and oxygen diffuse through
the adhesive polymers. Not ready for prime time now, and might not be
for a long time due to the lack of candidate impermeable adhesive
polymers. Suitable now for low power apps in benign envireonments
where long life is not important.