Effect of Solder Volume on Interfacial Reactions between Sn3.5Ag0.75Cu Solder Balls and Cu Pad
This study focused on the effect of solder volume on the interfacial reaction between Sn3.5Ag0.75Cu solder balls and Cu pads on PCB after various reflow soldering times. The diameters of the solder balls were 200, 300, 400 and 500 μm, respectively, and the opening diameter of the Cu pads was 250 μm. The solder volume ratio for the 200, 300, 400 and 500 μm balls was approximately 1:4:8:16. The interfacial intermetallic compound (IMC) was common scallop-type Cu6Sn5. The thickness of the interfacial Cu6Sn5 IMC layer was obviously thicker for the smaller solder ball after the same reflowing times from 1 to 5. After the first reflow, the thickness of the interfacial Cu6Sn5 IMC layer for the 200 μm solder ball was 4.39 μm compared to that of 3.15 μm for the 500 μm solder ball. The average diameter of the interfacial Cu6Sn5 grains for the smaller solder ball was significantly larger than that for the bigger one after the same reflowing times from 1 to 5. After the first reflow, the average diameter of the interfacial Cu6Sn5 grains for the 200 μm solder ball was 5.23 μm compared to that of 4.22 μm for the 500 μm solder ball. Both the thickness of the Cu6Sn5 IMC layer and the average diameter of the interfacial Cu6Sn5 grains increased with the increasing reflow time. The ratios of the average diameter of Cu6Sn5 grains to the thickness of the interfacial Cu6Sn5 IMC layer for all the four kinds of solder balls varied from 1 to 1.5, which showed a vivid growth of the interfacial Cu6Sn5 grains from the perspective of 3 dimensions. Based on the data from the experiment, the dissolution kinetics of the Cu pad can be simulated.
Luwei Liu Mingliang Huang
Electronic Packaging Materials Laboratory,School of Materials Science & Engineering,Dalian University of Technology,Dalian, China, 116024
国际会议
西安
英文
299-304
2010-08-16（万方平台首次上网日期，不代表论文的发表时间）