New analytical study for popcorn phenomenon (package cracking)

摘要

Package cracking during soldering is considered. This cracking is classified by two mechanisms. One mechanism is a classical MODE-I, whereby delamination originates under the die pad and propagates in most cases to the package's outer surface. The other is MODE-II cracking which starts from delamination at the die attach material interface. A simulated method of MODE-II cracking is established. Using this method, suitable properties of encapsulant to prevent MODE-II cracking are presented. These properties led to the development of a new molding compound, which has excellent resistance to MODE-II cracking.