SOP package surface discoloration after PCT test

Although the new assembly technology is developed well in this recent era, the conventional surface mount package technology such as dual-side small-outline package (SOP) is still useful to the common commercial IC products. If the IC products will be delivered to the market, they must pass the reliability tests such as the pressure cook test (PCT). Unfortunately, some tested products depicted an outlook of metal migration on the surface of the packaged ICs after this product reliability test. The stressed ICs with discoloration showed a function fail.