SMTA International Conference Proceedings

High Reliability Low Temperature Solder Alloys

Authors: Pritha Choudhury, Ph.D., Morgana Ribas, Ph.D., Raghu Raj Rangaraju and Siuli Sarkar, Ph.D.
Company: MacDermid Alpha Electronics Solutions
Date Published: 9/22/2019   Conference: SMTA International

Abstract: Economic, environmental and technical benefits have led to an increasing demand for low temperature solder alloys that reflow below 200C. Thermal stresses are lower and defects like warping are lesser during assembly. In a long term, this will allow the use of lower cost packages and substrates and enable thinner and advanced package designs. Eutectic SnBi alloys are suitable low temperature alternatives but also suffer from major drawbacks like inherent brittleness. The recent introduction of non-eutectic SnBi alloys with micro-additives has paved the way for replacement of SAC alloys in high mechanical reliability applications while reducing reflow soldering temperatures. In this paper, we will update the status of our ongoing work on developing Sn-Bi alloys having superior mechanical and thermal reliability.

Key Words: 

Lead-free, low temperature soldering, Sn-Bi alloys, drop shock, voids, reflow optimization

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