Some remarks to Graham Naisbitt's comments concerning silicon coatings:

We did some repair of soldered SMDs on silicon conformal coated
assemblies. The trick is to turn the solder liquid by a solder tip and
then twist the component to break the (thin, typical 50 to 100
micrometers) conformal coating. After removing of the component resolder
a new component (solder wire or solder paste). Then clean the assembly
and recoat.

If by osmotic effects high pressure may build up this should be combined
with significant increase in volume to lead to delamination of the
coating and subsequent spreading of the contamination. And silicone is
quite elastic. Is this really a concern?


Ulrich Korndörfer
ALCATEL SEL AG
Germany

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]>   *
* with <subject: subscribe/unsubscribe> and no text in the body.          *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************