Influence Of Solder Cap Thickness On The Interfacial Reaction In Cu/Sn/Ni Copper Pillar Bump

For a limited solder volume interconnect structure, bump interconnect reliability is more sensitive to the growth behavior of the interfacial intermetallic compounds(IMCs). The study of the effect of solder cap thickness on the interfacial diffusion reaction is of great importance to the application of copper pillar bump. Here, we investigated the effect of different solder cap thicknesses on IMCs and void growth. Cu/Sn/Ni copper pillar bump sandwich structure was prepared by multi-layer electroplating method with 5 mu m, 10 mu m, 20 mu m Sn layer, then aged at 150 degrees C for 24, 48, 84 and 108 hours without reflow. We find that the morphology, thickness and volume ratio of IMCs are significantly affected by the solder cap thickness. These results are instructive for the reliability of micro-bump interconnects.