Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


한국표면공학회지 (28권2호 67-76)

Microstructure Characterization of the Solders Deposited by Thermal Evaporation for Flip Chip Bonding

진공 증발법에 의해 제조된 플립 칩 본딩용 솔더의 미세 구조분석


한양대학교 공과대학 재료공학과;한양대학교 공과대학 전자공학과;전자통신연구소 반도체실장연구실;
한양대학교 공과대학 재료공학과;한양대학교 공과대학 전자공학과;전자통신연구소 반도체실장연구실;


The microstructure of 95wt.%Pb/5wt.%Sn and 63wt.%Sn/37wt.%Pb solders for flip chip bonding process has been characterized. Solders were deposited by thermal evaporation and reflowed in the conventional furnace or by rapid thermal annealing(RTA) process. As-deposited films show columnar structure. The microstructure of furnace cooled 63Sn/37Pb solder shows typical lamellar form, but that of RTA treated solder has the structure showing an uniform dispersion of Pb-rich phase in Sn matrix. The grain size of 95Pb/5Sn solder reflowed in the furnace is about $5mu extrm{m}$, but the grain size of RTA treated solder is too small to be observed. The microstructure in 63Sn/37Pb solder bump shows the segregation of Pb phase in the Sn rich matrix regardless of reflowing method. The 63Sn/37Pb solder bump formed by RTA process shows more uniform microstructure. These result are related to the heat dissipation in the solder bump.