Dear Technetters,

Recently we have encountered FC high-lead bump (95Pb5Sn) failures. Let me
first briefly decribe the package. It uses BT substrate, die is about
13x16mm, package size is ~ 27mm. The underfill thickess is about 100
microns. Solder bumps are about 100 microns in diameter. x-sections show
that all the failures are consistently the separation between the
oxidation layers under the aluminum pads. It also appears that the corner
towards the center of die separated earlier than the corner away from the
die center. The interfaces between the bumps and pads are OK. Have anyone
ever seen this kind of failures before. Any hints and helps are very
appreciated.

Thanks,

Yuan

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