Study on mechanical properties of innovative power IC attach joints

• Main Authors: Chun-Chieh Chang, 張駿杰
• Other Authors: 宋振銘
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/29898689055719216069

碩士 === 國立中興大學 === 材料科學與工程學系所 === 105 === Power devices such as invertors for electronic vehicles usually operate at temperatures higher than enduable temperature range for common Pb-free solders. Development of high temperature solders, as well as nano-Ag sintering technique, for the power IC attach applications are now under development. This study aims to evaluate the thermal stability of new innovative power IC attach joints bonded using BiAgX® solder pastes by reflowing, and Ag-Cu nanocomposite pastes with the copper formate additives developed in our lab by thermal-compression bonding, respectively. Microstructural feature and shear strength of the joints subjected aging at 150oC are investigated. Due to the alloying effect of minor Sn addition, joints, Cu3Sn formed at the interface of BiAgX®/Cu joints. The fact that shear strength of as-bonded BiAgX® joints was 28.4MPa and that of 800hr-aged joints was 22.9MPa suggests excellent reliability in high temperature storage. In contrast, the joint strength of nano-composite samples drastically decrease from 43.6MPa at as-bonded state to 16.8MPa when aged for 200 hr. After that, the shear strength of nanocomposite joint remained alsmost the same up to 800 hr. The as-bonded Cu-Ag nanocomposite joints possessed a homogeneous Ag matrix supersaturated with 1.86w% Cu. Subjected to aging, Cu atoms diffused towards joint interface and precipited to form Cu2O. This may account for the deterioration in joint strength.