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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