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Solderability issues due to excessive nickel

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#72967

Solderability issues due to excessive nickel | 27 October, 2014

Hello,

We are facing solderability issues on a particular lot of board. THe Nickel thickness measured with an XRF is around 400 U inches. Spec calls out for 130 u inches Nickel and 3 - 5 U inches gold over it.

Assuming there is no porosity on the gold. Is there any explanation as to why we are seeing solder wetting issues? Profile seems to be running at good peak and TAL. Running Lead free SAC 305.

THanks!

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#72982

Solderability issues due to excessive nickel | 30 October, 2014

Rather than asking why, maybe the better response is to reject the PWBs and have them re-fabricated correctly?

Of course circular reasoning tells me that the reason for your issues is that you have 3x the amount of nickel beneath the gold.

I wish I was metallurgist enough to know the exact answer, though.

No help, I know, but a bump nonetheless.

'hege

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#72983

Solderability issues due to excessive nickel | 30 October, 2014

Why soldering issues? I'd guess the nickel is corroded. It is very difficult to solder to oxidized nickel. Your SAC305 would get kicked all the way down the conveyor by nickel oxide. A lack of Ni-Sn-IMC formation will confirm this dewetting .

What's the deal on 400 uin nickel thickness? Plating nickel thicker than 250 uin is difficult to control

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