[sdiy] BP Electrolytics & Obscure Solina ICs?

[Tom Wiltshire]

On 6 May 2007, at 23:21, Michael Ruberto wrote:
>
> Regarding the console I'm now thinking the corrosion I see isn't  
> caused by cap leakage afterall. I desoldered some of the caps off  
> the PCB and after inspecting them I don't see signs of leakage on  
> them. The bottoms of the caps and the areas where the leads connect  
> are clean. I now suspect the glue that was applied to them. The  
> glue on the BP caps is darker than the glue used on the other caps  
> around the PCB. Where this glue comes in contact with any metal  
> there is heavy corrosion. OTOH the glue on the polar caps is a  
> light color and there is no corrosion where it comes into contact  
> with metal. The smaller caps which aren't glued at all have no  
> corrosion near them either. Is it possible they used a glue formula  
> that became highly acidic over the years?

I worked in the repair dept. of an electronics manufacturing company  
that had enormous problems with one particular type of data-logging  
unit. The problems were caused by a silicone sealant that had been  
used to seal the enclosures against water ingress. Unfortunately, the  
sealant gave off acetic acid fumes, which over time ate the copper  
tracks on the PCB. It didn't have to be particularly acidic - over  
time it was enough to damage fine tracks on a PCB (the board used  
surface-mount ICs).

So I'd say your guess is a good possibility.