Optimal Interface Strength of Lead Free Solder Ball to IC Package Subjected to High Thermal Loading and Electromigration

• Main Authors: Lin, Yu-Min, 林昱旻
• Other Authors: Thaiping Chen
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/33827045581189437381

碩士 === 和春技術學院 === 電機工程研究所 === 98 === In the structures of IC package, Pb free solder ball is very important key. Solder ball may produce the void between interface of solder and package under electron movement and thermal condition. The interface becomes brittle. The reliability of electronic equipment may become poor. The purpose of this research is to study the solder ball adhesion effect to IC package subjected to electrical and thermal loading. The specimens were experienced different electrical currents and storage temperatures. Then, adhesive strength and electrical resistance between Pb free solder ball and Cu layer were measured respectively. The variable resistance for joint of solder ball and Cu layer represents electron movement level. To design experimentally controllable factors is applied Taguchi method. There are four controllable factors which are storage time, solder ball size, storage temperature and current density. The damage mechanisms were conditioning to storage temperature and current density. The uncontrollable factors, adhesive strength and electrical resistance, were measured by shear test and micro resistance test respectively. Two optimal indexes were found for adhesive strength and electrical resistance respectively. Finally, the optimal case of the multiple performance characteristics index (MPCI) was obtained for joint strength of Cu and solder ball. MPCI is only one index and represents entire joint strength. MPCI is combined from two indexes of adhesive strength and electrical resistance by applied fuzzy logic.