Pad finish related board-level solder joint reliability research

Abstract

Pad finish is the direct interface between PCB and solder ball, it plays an important role in determining the compound and characteristics of IMC formed at those interfaces, and even to change the mechanical property and microstructure of bulk solder joint. In this paper, we investigated the reliability property of 10 different pad finish combinations. The substrate finish includes electro-plated NiAu, ENEPIG with different Gold and Palladium thickness, and OSP. Board side finishes are ENIG and OSP. We have set up the database of life data for all groups under different reliability test conditions and found out the pad finish related failure mechanism.