High thermal conductivity underfill study for fine pitch Cu pillar bump

Along with the die size of device become more and more small, fine pitch, fine gap and multi-stacking are the market mainstream which applied for high performance system in advance technology, su ch as 3D IC. Th erefore, h eat dissipation is must process for this kind of electronic device to avoid internal heating form device during operate. Un derfill (UF) is an important process in 3D stackin g flip chip package that major function is reducing stress from coefficient of thermal expansion (CTE) mismatch, also can isolate bump and protect it. In this study, two kinds of fillers are evaluated on the heat dissipation which one is Silica and the other is Alumina. In order to clarify the performance of the test results, adhesion test was performed by pudding model on the silicon nitride. In addition, UF filing and flowing capability was determined by scanning acoustic tomography (SAT). Thermometer was used to analysis heat dissipation for comparing the effect of different UF filler material.