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This paper presents a study of the resistance of solder joints to failure when subjected to strain rates that simulate the conditions of drop impact on a portable electronic product. Two test methods are used in this study: board-level drop/shock test (BLDT) and component-level ball impact test (BIT). The performance of 12 material combinations consisting of 6 solder alloys and 2 pad finishes were investigated using these two test methods, and analysis of correlations between the methods was performed. Quantitative correlation and sensitivity coefficients for the failure modes and the measured characteristics, namely, number of drops to failure for BLDT and peak load, total fracture energy, and energy to peak load for BIT, were evaluated. Analysis of the test results indicates that there is a lack of universal correlation between BLDT and BIT. Nevertheless, BIT can still serve as a test methodology for quality assurance in view of the strong correlation between the measured BIT characteristics and the failure mode. The total fracture energy parameter is preferred over the peak load and energy to peak load due to its higher sensitivity and reduced susceptibility to measurement error.
Date of Conference: 22-24 Oct. 2008