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ENIG-BLACK PAD!!!!

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Jack

#45979

ENIG-BLACK PAD!!!! | 5 December, 2006

It is very common to relate ENIG pad surface finishing with BLACK PAD defect. However, is anyone know why BLACK PAD defect only happen on fine pitch pad areas suach as BGA, QFP? Why this defect did not or seldom happen on capacitor @ resistor pad??

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RDR

#45983

ENIG-BLACK PAD!!!! | 5 December, 2006

I do not see this same scenario.

Russ

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#45994

ENIG-BLACK PAD!!!! | 5 December, 2006

I would suspect if you had a full evaluation done there would be the same issue with Nickel oxidation everywhere. The reason BGA's fall off (or have solder connection issues first) is due to their size. A slight flex in the board has a much larger impact on a big part than a small part. One other issue, we are seeing BGA's with non-eutectic balls more frequently today and if you do not profile to accommodate for that mild black pad will seem like the worst BP you have ever seen on BGA's but not so evident on smaller parts.

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Jack

#45995

ENIG-BLACK PAD!!!! | 5 December, 2006

Hi Doug,

I think you are right..Let me do some EDX on other location to see any nickel oxide...BTW, is this black pad reworkable?? If yes, how?

Thanks in advance,..

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#46006

ENIG-BLACK PAD!!!! | 6 December, 2006

Not to my knowledge it is not.

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Cmiller

#46080

ENIG-BLACK PAD!!!! | 7 December, 2006

it is not that I am aware of either. Make sure you get your boards from a house that does the gold plating in-house or you will continue to have the problem. The gold needs to be plated immediatly after the nickel, not a few days later. I have only had this problem twice in nine years but the result is the same, SCRAP. Both times we found out the gold plating was outsourced and we were lied to.

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Jack

#46085

ENIG-BLACK PAD!!!! | 8 December, 2006

Hi all,

I found this article (Dealing with "the black pad defect)about reworking bare PCB with black pad symptom...Use HASL to treat black pad..Have you guys try this before??

www.smta.org/files/SMTAI01-Jay

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Cmiller

#46102

ENIG-BLACK PAD!!!! | 8 December, 2006

I cant seem to get to that link but we tried everything we could think of and there was no way we found to get solder to adhere to the pads. I guess if you took a burnishing brush and polished the nickel off and got down to the bare copper you may be able to solder that fine but you would have to be carfull not to take the copper down too thin.

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Jack

#46110

ENIG-BLACK PAD!!!! | 8 December, 2006

Re-address the link...

http://www.smta.org/files/SMTAI01-Jay.pdf

Look at the last page about bare board reparing..

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Jack

#46323

ENIG-BLACK PAD!!!! | 20 December, 2006

Hi all,

Any comment after read this article?

Best wishes, Jack

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#46347

ENIG-BLACK PAD!!!! | 21 December, 2006

Waving the board will sweap away the crud of black pad and to produce a solderable surface, but this surface may have too much solder and may not be very flat. This can create problems when printing paste and placing and soldering components, depending on the design and the component.

A more straight forward solution is returning the boards to your fab for credit and finding another fab that has the proper experience and production capability.

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Jack

#46369

ENIG-BLACK PAD!!!! | 23 December, 2006

Hi Davef,

I think you are right..Rgds, Jack..

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