Study of Substrate Materials on Bias-HAST Reliability of Fine Pitch FCBGA Package

This study is to investigate the effect of relationship on substrate material (including ABF and solder mask) after JEDEC bias-HAST condition. As a result, adhesion degraded between the solder mask to ABF material by moisture sensitivity level 3 test. Therefore, copper dendrite formed and grew along solder mask to ABF interface or through solder mask and touch another copper trace caused short after bias-HAST test. At this paper, an ECM corrosion failure model of substrate and mechanism of dendrite growth condition of copper trace will be discussed, also interacted design & material property of substrate, to identify selection & design risk on copper to copper for substrate material.