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Reply To: | TechNet E-Mail Forum. |
Date: | Thu, 22 Oct 1998 07:40:00 +0200 |
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Hi ,
Many of PCB manufacturers knows this phenomena all along PCB manufacturing :
1 ) "Stubborn " lines in innerlayers , that are reluctant in black oxide .
This is being explained by galvauc action of titanium parts in black oxide tank
2 ) Certain pads and lines in stage of tin-lead ( as etch resist ) on
outerlayers
3 ) Problems in electroless Nickel -immersion Gold . Mainly on the same
problematic areas , that appeared during tin-lead stripping .
There are some theories , but I never had opportunity to get practical
advices on " do - do not do level " .
I am anxious learn more about it .
Regards
At 18:39 20/10/98 -0400, you wrote:
> Hi
> My question is about galvanic action on panels being fabricated.
> What I am seeing is that certain areas of panels are reacting
> differently in certain processes. These pads are internally connected
> to each other. The panel has the normal pattern plate and Ni/Au as
> well.
> The pads look different from the surrounding pads and etch at a
> much higher rate in microetch. I would like to know how common this is
> and what can be done to eliminate or at least bring it to an
> acceptable level.
>
> MikeDoty
> P.E. Hadco TCE
>
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Edward Szpruch
Eltek Ltd - Israel
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