Re: Conformal coating of circuit boards(All Audi content)

[e6941tb@ix.netcom.com]

Anton Gaidos III wrote:
> 
> All,
>  At one time, if at all did Audi begin to put a conformal coating on the
> engine management circuit boards? I have been doing a three day training
> class about high-speed logic circuits and while talking about the
> properties of various conformal coatings, epoxies, urethane etc. my
> instructor pointed out Audi. You'll all recall this as one of those Audi
> disasters which now makes it easy for us to get second hand Audi's
> cheap. At one point Audi and probably all car manufacturers simply did
> not coat their boards. When condensation builds up, unprotected traces
> have a perfect opportunity to create contact between two running
> parallel. I have seen films of this happening very quickly.
>   If none of Audi's boards are conformally coated, I would highly
> recommend this be something we all do at the
> time of chip upgrades. It is simple to clean the surface and give it a
> quick spray.

Amen to that. 

The board house, that I use, has just screwed up the whole batch of my
new signal conditioners by neglecting to conformal coat the boards
(5-layer, extremely dense surface mounted sandwich). The circuit listens
to nanoampers of a current gradient, but even at these low currents I
can see some parasitic leaks between the traces, caused by flux residue
and air moisture.

Igor Kessel, 
EE
'89 200TQ