Black Pad article in SMT Magazine

Black pad was a big problem a few years ago when ENIG (Electroless Nickel Immersion Gold) finish boards first started popping up. It's not so much of a problem these days, but we do still see it from time to time.

Sc_black_pad_illustration If you think you may be having black pad problems with you ENIG boards, or similar problems with immersion silver boards, Check out the article Screaming Circuits recently had published in SMT Magazine online.

Just note that down near the end of the fifth paragraph, I say that problems with the "tin" layer lead to black pad. It's really the nickel layer that causes the problems. I inadvertently said tin. One of our readers pointed that out to me. Oops.

Duane Benson
Don't look; Heisenberg may have been right...

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Comments

People discuss the cause and avoidance of black pad. So what's the impact of black pad
i. If it were to happen on a solder pad?
ii. What if the black pad happens on a gold contact pad only?

Hi Fakhrozi; My understanding is that the cause of black pad comes at the board house. That being said, I do suspect it's possible for the problem to show up after a rework cycle that included pad dressing instead of after the original solder pass. The solution would still be to work with your board house.

Rework can cause pad lifting and other similar issues that look like black pad though.

Any one else, with thoughts, feel free to chime in.

Can the Black Pad issue (coresponds to Ni corrosin) happen due to BGA pad dressing process?

thank you

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