Lead-Free Solder-Joint-Reliability Model Enhancement

Upon release of electronics products with lead-free (Pb-free) solders starting in 2006 and driven by the EU’s RoHS legislation, a few models have been in use by the electronics industry to predict the life of the Pb-free solder joints under product- application conditions based on accelerated testing results. These models, including one published by HP in 2005, have proven to have shortcomings, resulting in any of three probable scenarios: (1) over-design for reliability, (2) earlier-than-predicted field failures, or (3) missed technology opportunities. We have devised an approach to develop and implement improved models for predicting Pb-free solder joint life. This approach comprises: (1) comprehensive review of available published work to create a large data base of test results, (2) application of statistical techniques to analyze this large data base, and (3) the grouping of the data into clusters of comparable packaging attributes and test conditions. Using this new approach, a set of accurate models has been generated that significantly reduce the errors and uncertainties compared to earlier models, greatly enhancing HP’s ability to accurately predict Pb-free solder-joint life based on test data.