Steve,

My initial reaction to your comments are that the fabricator has liquid leaking back out of the vias after curing.

I'll explain why I believe this:

If it were a curing problem causing peeling it would be more widespread
If it were poor adherance at the copper (i.e. via pads, trace, etc) you would see peeling in those other places as well
If the copper was contaminated, it would also be affecting other areas than vias.
Component holes being larger than vias would drain of liquids better than vias
Vias being tented can entrap liquid if precautions and proper processing are not performed, and this is what I believe is happening.

I have seen this happen a few times here at our place.

Keep in mind I am basing this solely on the information available, I could be way off base...

Curious to know how this evolves though...

Franklin D Asbell

----- Original Message -----

From: Stephen R. Gregory <[log in to unmask]>

To: <[log in to unmask]>

Sent: Friday, February 11, 2000 8:12 AM

Subject: [TN] Solder mask failing tape test..

> Mornin' all!!
>
> This morning I got a email from one of our buyers telling me that one of the
> boards at one of our fab shops is being held-up because it doesn't pass their
> solder mask tape test. My buyer said that they told him that the mask is only
> coming off the via's, and it was because of uncured mask. The mask is a LPI
> and the via's aren't meant to be tented. Also the board doesn't go through
> wave solder as the only through-hole is hand soldered because it goes up
> through the board from the bottomside.
>
> My buyer is asking me if we should accept the boards. I have a few concerns.
> One thing is that if there is uncured mask at the via's, what guarantees are
> there that there isn't more at other places on the board? Shouldn't uncured
> mask be a simple thing to fix by either baking the PCB (if it's a thermal
> cure), or exposing it to more UV (if it's a UV cure)?
>
> Further still, does uncured mask come off in a tape test? Or is mask coming
> off from a tape test more an indication of an adhesion problem from
> contamination?
>
> Thanks in advance for all replies,
>
> -Steve Gregory-
>
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