A Study of Thermal Stress and Failure Mechanism of Solder Jointsfor Thin and Fine-pitch Ball Grid Array Package

• Main Authors: Chien-Ho Chen, 陳建和
• Other Authors: Wen-Fung Pan
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/y6wxhj

碩士 === 國立成功大學 === 工程科學系專班 === 90 === The major reliability issue of Ball Grid Array package is solder joint crack due to thermal expansion mismatch between joined materials.In this study, a nonlinear finite element mode was used to analyze solder joints under the thermally induced stress and failure mechanism during thermal cycling between -55℃ and 125℃. The Ansys software was performed to compute the thermal stress and plastic strain. The Coffin-Manson formula was used to predict the fatigue life.It is found that the maximum von Mises stress occurs at the outest corner solder joint . The plastic strain range of solder joints in hourglass shape is less than the ones in barrel shape. The smaller pitch and the joints with larger solder pad area result in less stress. The reliability of BGA package is dramatically improved by decreasing the peak thermal stress.　These empirical correlations would be very useful to design engineers in selecting the electronic packaging materials and their properties to reduce the peak stress on the critical electronic devices.