Optimal design of PBGA mixed solder joints under random vibration

This article provides a method to perform finite element analysis (FEA) and theoretical analysis on stress and strain characteristics of plastic ball grid array (PBGA) assembly under the random vibration environment. For the mixed solder joints, ball diameter, ball pitch and ball array were selected as three critical parameters. By using a L₉ (3⁴) orthogonal matrix, the mixed solder joints of PBGA components which have nine different technology parameter combinations were designed. In order to investigate the distribution of stress and strain of mixed solder joints, random vibration simulation for the PBGA assembles was simulated. Based on the stress value, range analysis was researched. The results indicate that the maximum stress of PBGA occurs at the outside corner of solder joints matrix and concentrates on the interface between the solder ball and pad near the PCB. In this study, the stress of mixed solder joints is affected by solder ball array, ball pitch, ball diameter in a descending order, and the maximum stress of the mixed solder joints is inversely proportional to all of them. The results lay a basis for high reliability design of PBGA assembly for engineering application.