Assessment of Factors Influencing Thermomechanical Fatigue Behavior of Sn-Based Solder Joints under Severe Service Environments

Abstract

Reliability of solder joints under thermal excursions encountered in service depends on the solder performance during each stage, its extent in each cycle of temperature excursion, and the cumulative effects of the same under repeated thermal cycling. Extent of such field influence, and the resultant damage, will also be significantly affected by the constraints imposed by the solder joint geometry. Any realistic evaluation of the solder joint behavior should account for all of the above with specimen geometry, and thermal excursion stages that are representative of the actual conditions, encountered in service to arrive at meaningful results. Findings based on studies carried out to evaluate the roles of each of these, with specimens possessing same geometry and prepared under the same conditions, indicate the important contributions of each of the service and material parameters, and the solder alloy composition, for reliability considerations.