Tight-Pitched 10 μm-Width Solder Joints for c-2-c and c-2-w 3D-Integration in NCF Environment

Solder micro-joint (μ-joint) fenced with non-conducting film (NCF) under tight pitch configuration has been studied for its thermal and electrical stability after chip-to-chip and chip-to-wafer integaration via thermal cycle (TC) test and Kelvin measurement under constant-current-stressing (CCS). For the optimized flip-chip bonding parameters, we have obtained 28-30 mΩ resistance for a single Cu-SnAg μ-joint of 10 μm in size at 20 μm pitch configuration. We hardly observed any change in the μ-joint resistance after 500 cycles of TC test as well as CCS for 100 ksec at 100 °C. Both the TC and the CCS results confirm that 10 μm-sized solder μ-joints fenced with NCF under tight-pitched configuration were successfully formed for 3-D chip stacking applications.