Sensitivity analysis of factors influencing MEMS package reliability

The solder joint is one of the key weakness points that influence the reliability of MEMS package, for maximum stress-strain will be produced under high-g impact, which may result in plastic distortion or even crack in solder joint. Based on the dynamic analysis of Finite Element Model (FEM), sensitivity analysis is conducted on a typical MEMS package (Leadless Chip Carrier, LCC) for the dependence of the maximum stress of solder joint on design parameters such as structure material, geometry size and shape. The dependence of the maximum effective stress of solder joint on materials (PCB and solder) properties such as density and Young´s modulus are discussed in detailed, and the Young´s modulus (both of the PCB and solder joint) has a significant influence on the maximum stress of solder joins; The maximum stress of solder joint is found increase with the PCB width increasing, while decrease with the increasing of PCB thickness, and the PCB thickness has a significant influence; With the volume of the cavity increasing, the maximum stress of solder joint is found decrease; With the solder height increasing, the maximum stress of solder joint is found increase; With the cover thickness increasing, the maximum stress of solder joint is found decrease; the maximum stress of solder joint is smaller when the shape of PCB is round.