A STUDY ON PARAMETERS THAT IMPACT THE THERMAL FATIGUE LIFE OF BGA SOLDER JOINTS

Estimation of the thermal fatigue life of solder joints and identification of parameters that enhance the fatigue life are important steps in the development stage of BGA packages. In this study, different parameters of Sn-Ag-Cu 305 BGA (Ball Grid Array) solder balls are investigated to understand their impact on the number of cycles to failure under thermal fatigue life tests. Initially, accelerated thermal cycling fatigue tests on two electronic packages were conducted by three different vendors and it was observed that the results were significantly different. The first part of this study dwells into understanding the influence of parameters such as the solder mask design; SMD and NSMD, the variation in the solder ball geometry, copper pad thickness and diameter and material properties of the PCB on the accelerated thermal cycling performance of the BGA packages. The later part deals with understanding the root cause for the variation in the estimated life of two BGA packages by the three different vendors.