Originality method in selecting high CTE molding underfill for low profile molded FCCSP

Abstract

In this paper, we propose a originality method in selecting high CTE molding underfill to control the warpage of low profile molded FCCSP with 0.8mm package height. A test vehicle was designed with package size of 7.5x7.5mm and die size 6.5x5.9mm with 65nm low K chip, the package height is 0.8mm after solder ball reflow, total IO count is 196 (Figure 1). We will demonstrate the warpage comparison of normal CTE (10~12) & high CTE (≫12) molding underfill and the reliability test results. In this study, the experiment result can achieve our expectation which warpage is less than 3mil and the reliability had passed MSL3 (Moisture Sensitivity Test, 60°C/60% ,40 hours + 3 times of IR260°C.), TCT (Temperature cycling test, −55 ~ 125.) 1500 cycles, HAST (High accelerated stress test, 130~C/85% R.H) 100 hours, TST (Thermal shock test, −55 ~ 125°C) 500 cycles and HTSL (High temperature storage life, 150°C) 1000 hours.