Journal of SMT Article

Isothermal Fatigue of High Temperature Solder Joints

Authors: Harry Schoeller, Ph.D., and Gregory Parks
Company: Universal Instruments Corporation and Annapolis Micro Systems
Date Published: 4/1/2017   Volume: 30-2

Abstract: With electronics being integrated into higher temperature environments such as those associated with deep well drilling and distributed controls for “under the hood” automotive applications, higher melting temperature solders are needed. While limited data on bulk high temperature solders is available, data on joint level behavior is woefully lacking. Further, the data presented is often measured at room temperature and cannot be extended to higher service temperatures where the solders are actually used.

In this work, a test methodology was developed for high temperature isothermal shear fatigue of individual solder joints. A total of six solder alloys, five Pb-based alloys and one Pb-free alloy were tested at 25°C and 200°C. Joints tested at 200°C were first stored at 200°C for 1000hrs to measure performance in a simulated high temperature environment. The microstructure was studied in conjunction with the fatigue results to understand the structure-property-performance relationship. Result show those alloys with a dendritic structure had a greater characteristic life at room temperature. At 200°C coarsening of the microstructures led to dramatically different results.


Key words: Isothermal Fatigue, High Temperature, Microstructure, Solder Alloys

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