Bonding temperature effect on the performance of flip chip assembled 150nm mHEMT device on organic substrate

In this paper, due to the rapid growth of wireless communication systems, high frequency packages become very important and they require compactness, low cost and high performances even at frequency up to 60 GHz. Flip-chip assembly using organic substrate at very high frequency has become a cost competitive packaging method in semiconductor industries. The coefficients of thermal expansion (CTEs) of GaAs chip and RO 3210 organic substrate are 5.4 and 13 ppm/K, respectively, which result in a large CTE mismatch in flip-chip package. The effect of thermomechanical stress is generated by the CTE mismatch from the package materials in the assembly. In this work, a demonstration of flip-chip assembled In_0.52Al_0.48As-In_0.6Ga_0.4As mHEMT on organic substrate is presented. The DC and RF characteristics of the package were measured and compared to the bare die data at operating frequency from 2 to 110 GHz. Correlation between flip-chip bonding temperatures and the RF performance is investigated in this study.