Investigations on the Electrical Properties and Material Reaction Behavior of Solder Bumps Produced by Stencil Printing

• Main Authors: Yu-Lan Chang, 張毓藍
• Other Authors: Kwang-Lung Lin
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/58066995814221539239

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 91 === The objective of this research was to investigate the mechanical and electrical properties of solder bumps produced with solder paste by printing. The shear strength of solder bumps and the interfacial reaction behavior between solder and UBM was investigated after reliability tests. Besides, it was also to measure the electrical resistance of flip chip bonded solder joints and to investigate the correlation between the change of the electrical resistance and the reaction behavior of the materials after different environmental tests. The interfacial investigation of solder bump indicated that Ni3Sn4 was formed. It was also observed that the (AuXNi1-X)Sn4 was formed between the Ni3Sn4 layer and solder after aging. A raise in aging temperature enhances the growth of (AuXNi1-X)Sn4 and inhibits the growth of Ni3Sn4. The average shear strength of solder bumps after reflow was about 50g, and the fracture occurred at the solder. It was also found that the shear strength of solder bumps was decreased with reflow times and aging time. But the fracture still occurred at the solder after reliability tests. The experimental results revealed that the lowering in shear strength was not induced by intermetallic compounds. The intermetallics exhibit a good adhesion between solder and UBM after reliability tests. The electrical test results showed that the increase of electrical resistance of solder joints after the multiple reflow test and high temperature storage test was ascribed to the growth of intermetallic compounds. In addition, the oxidation of solder and elimination of defects also affect the electrical resistance of the annealed solder joints. Furthermore, it was found that the electrical resistance of the solder joints greatly increases after the humidity-temperature test and thermal cycling test. The humidity-temperature test affect the electrical resistance of solder joints through the circuit corrosion and oxidation of solder. The thermal cycling test resulted in the formation of crack which caused the solder joint failure.