I'm not sure this applies...I have seen first hand another failure of EN
separating from copper, although prior to assembly. An operator
mis-calculated the copper microetch rate leading to insufficient copper
roughening. The problem was caught when inspection tape tested the ENIG and
pulled up nickel from the copper surface. Operator logsheets contained the
raw data for the etchrate calculation so a swift root cause was mercifully
easy. Process wise we dumped and remade the acid pre-dip each day as Rudy
mentioned.

I hope this helps in some way.

Russ


>From: Gaby <[log in to unmask]>
>Reply-To: "TechNet E-Mail Forum." <[log in to unmask]>,
>Gaby <[log in to unmask]>
>To: [log in to unmask]
>Subject: [TN] Nickel separation
>Date: Sat, 5 Jul 2003 01:18:26 +0200
>
>Dear TechNetters,
>We encountered an unusual failure .
>After mounting and reflowing BGA's on a ENIG plated board, they failed the
>electrical test showing opens and intermittent contact.
>We tried to repair the failure by reflowing them again with our SRT, after
>developing a good profile. The result was that some of the opens
>dissappeared, but new ones appeared.
>We decided to remove the failed BGA and replace it with a new one. After
>removal of the old component , we tried to prepare the circuit pads for
>replacement. During this operation we observed that the nickel plating
>separated from the copper on many pads and after performing a cross section
>of the area. we saw that other pads had nickel separation and solder under
>the nickel (which creeped there during pad preparation).
>It is the first time that I saw this failure.
>Any comments?
>Gaby
>
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