Impact of package design and materials on reliability for temperature cycling, bend, and drop loading conditions

This paper presents a collection of test data showing how the choice of package design and material can have a different effect on performance depending on the loading conditions. Board level temperature cycling, drop (JESD22-B111), and cyclic bend (JESD22-B113) tests were performed on 0.4mm ball pitch packages. Factors investigated for this evaluation include mold compound material, mold cap thickness (0.45 vs. 0.7mm), ball pad finish (NiAu vs. Cu OSP), solder ball composition (SAC305, SAC105, SAC125Ni, Sn3.5Ag), solder volume (ball vs. bump), package material (RoHS vs Green), and board material (RoHS vs Green). The data presented in this paper indicates that lower silver content solder balls perform better under drop conditions, while temperature cycling reliability suffers as silver content decreases. In addition, mold compound material and thickness, die size, and solder volume have the opposite effect depending on the loading condition. The Green material for test board also showed lower performance than RoHS compliant board material.