BGA Reballing Reliability

摘要

During the solder ball removal process, the manual method using wicking braid resulted in the BGA being subjected to fewer thermal stresses than would be encountered with a flowing solder bath method.rnIt was expected there would be significant copper dissolution when using a Pb-free flowing solder bath to remove the solder balls. However, the robust nickel layer on these particular devices appeared a very effective barrier, preventing solder from leaching the copper from the device lands.rnAll devices passed all electrical tests after numerous thermal cycles.