Solder interface locking using unidirectional growth of an intermetallic compound

摘要

A ball grid array device includes a substrate, further including a first major surface and a second major surface. An array of pads is positioned on one of the first major surface or the second major surface. At least some of the pads include a barrier layer having pores or openings therein. When solder is placed on the pad, the barrier layer forms an intermetallic compound at a rate different from the rate of the intermetallic compound formed between the pad and the solder. The result is a solder ball on a pad that has a first intermetallic compound and a second intermetallic compound.