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Black PAD

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yqdeng@gsl.com.hk

#42133

Black PAD | 13 June, 2006

What is "Black pad"in ENIG(Electroless nickel/immersion gold), how to solve if it happen in SMD BGA solder joint?

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#42138

Black PAD | 13 June, 2006

Search the fine SMTnet Archives for background on black pad. If you have black pad on your boards, return them to your supplier.

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Bob R.

#42151

Black PAD | 13 June, 2006

Also be careful in assuming you have black pad. A nice straight crack along the Sn-Ni intermetallic is probably just overstress at some process (most likely ICT). The better board suppliers figured out how to avoid black pad years ago.

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YQ DENG

#42178

Black PAD | 14 June, 2006

How to check incoming bare PCB black pad phenomenon?

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#42187

Black PAD | 14 June, 2006

There is an IPC test method involving a tape test, which you can try for a start. Look at the IPC TM-650 free on the IPC site. Black pad occurrences are much reduced, but I don't believe you can say they never happen, even to the better board houses. That's why we do not use ENIG.

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#42201

Black PAD | 14 June, 2006

We too do not use ENIG. Too expensive and risky.

Implementing a Simple Corrosion Test Method to Detect "Black Pad" Phenomenon in Electroless Nickel/Immersion Gold Plating ; BabHui Lee; Circuitree 11/1/03 http://www.circuitree.com/CDA/Archives/34f2b343900f7010VgnVCM100000f932a8c0

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#42220

Black PAD | 15 June, 2006

Davef,

May I ask, what do you use?

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#42233

Black PAD | 16 June, 2006

We use HASL and immersion silver, depending on the board design.

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#42240

Black PAD | 16 June, 2006

Thanks Davef,

We recommend ENIG to our customers at this time, we have not had any customers reporting issues with it so far. I like the protection of the nickle from copper dissolution during wave in a PB free scenerio, but the "Black-Pad" issue is all-ways in back of my mind for some reason.

Thinking of going the immersion silver route in the future, collecting data now.

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YQ Deng

#42260

Black PAD | 19 June, 2006

Thanks very much!

In fact, "Black PAD" phenomenon have been found in our product, the total BGA came off PCB during drop test. if we apply the underfill to BGA after SMD process, Could the underfill add reliablility of product?

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#42286

Black PAD | 19 June, 2006

While underfilling BGA "mounted" on blacked pad boards could improve the reliability by attaching the BGA to the board, you should believe that all components soldered to the board will be affected by the black pad, not only BGA.

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