Contact resistance of the chip-on-glass bonded 48Sn-52In solder joint

Abstract

An average contact resistance of a COG joint bonded with 48Sn-52In solder was characterized using daisy chain structure. The average contact resistances of the 48Sn-52In solder joint of 29 mu m diameter and 14 mu m height were 132 m Omega/bump. 28.5 m Omega/bump, and 8.6m Omega/bump on Ti(0.1 mu m)/Cu(1.5 mu m), Ti(0.1 mu m)/Cu(1.5 mu m)/Au(0.1 mu m), and Ti(0.1 mu m)/Cu(3 mu m)/Au(0.1 mu m) UBMs. respectively. Such difference in the average contact resistance of the 48Sn-52In solder joint on each UBM could be attributed to partial oxidation of the Cu UBM layer during solder evaporation and a difference of the thickness of the Cu UBM layer remaining underneath the intermetallic compounds after soldering.