The dissolution rate of copper in the molten solder with current stressing

• Main Authors: Chien-Zong Huang, 黃建融
• Other Authors: C. Robert Kao
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/37233324838846256742

碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 93 === The electromigration of solder at solid state was studied in the past, but it was not discussed at liquid state. In this study, we take the micro capillary to design a Cu/solder/Cu structure. We make the marker on the copper wire with the distance of 300 �慆 from the head. At 240 °C with current stressing of 6.3×103 amp/cm2, the copper wire at cathode dissolve rapidly. For up to 3 hr with current stressing, the consumption of copper at cathode was 125 �慆 and there was a lot of IMCs formed at anode. At 185 °C with the same current density and stressing time, the consumption of copper at cathode was only 1 �慆. For up to 3 hr at 255 °C without current stressing, the consumption of copper was 8.5 �慆. And it was about 1 �慆 at 200 °C. The result of this study indicate that temperature is important as much as the current density in the consumption of copper. We will disscuss the phenomenon in detail, and it was useful to analyze the failure mechanism in flip-chip solder joints. Electromigration will induce local melting in flip-chip solder joints, then lead to the serious dissolution of copper and fail finally.