EVALUATING SOLDER JOINT FATIGUE RELIABILITY BY MOIRÉ INTERFEROMETRY
Author: Cemal Basaran Company: University at Buffalo, SUNY Date Published: 6/12/2001
Advanced Packaging Technology
Abstract: The study of solder joint reliability is a significant issue in electronic packaging. Solder joints are subjected to cyclic strain due to thermal expansion mismatch between the bonded layers, as a result they undergo elastic, plastic and creep deformations, and finally experience microcracking and damage. There is very little test data available in the literature about thermomechanical response of actual micron scale solder joints in BGA products. In this study, a ball grid array (BGA) package was thermally cycled between -55 degrees C and 125 degrees C by using a large capacity Super AGREE thermal chamber. High sensitivity Moiré Interferometry is used for measuring the irreversible strain field during cycling. A novel specimen preparation technique allowed us to measure irreversible strain accumulation up to failure. The technique used casts a new look in the application of Moiré Interferometry method to fatigue testing. Previously reported similar studies in the literature included one thermal cycle only. This new technique allows recording plastic deformations up to failure of the solder joint.