SMTA International Conference Proceedings

Effects Of Aging On The Secondary Intermetallic Layer (Cu3Sn1) For SAC305 Solder

Authors: Kelsey Fitzgerald, Jay Marshall, Teneil Ryno, Andrew Kelley, and Clay Voyles
Company: South Dakota School of Mines and Technology and Radiance Technologies Inc.
Date Published: 10/16/2011   Conference: SMTA International

Abstract: With the transition from lead based solder to lead-free solder in electronics manufacturing, several reliability issues have emerged. These issues include copper dissolution, tin-copper intermetallic formations, and tin whiskers. Several research studies at South Dakota School of Mines and Technology (SDSM&T) have focused on quantifying the affect intermetallic formations have on electronic systems. This research project investigates the Cu3Sn1 (e phase) intermetallic formation at the solder-copper interface with respect to thermal aging times and temperatures. By analyzing the growth kinetics of the intermetallic layer and by observing the degradation of the solder-copper bond, the influence of thermal aging is further understood. In this research project, samples were manufactured with SAC305 solder paste applied to a copper substrate. The samples were reflowed with identical application parameters, and then subjected to an array of thermal aging times and temperatures. Samples were aged at 50, 70, 80, 90, 100, and 125 °C, and analyzed in approximately 100 hour intervals. The thicknesses of the intermetallic compounds were then recorded, as well as the presence of Kirkendall voids.

Key Words: 

Intermetallic Formation, Cu3Sn1, Copper Dissolution, SAC305 Solder

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