Electrical measurement of a lead-free solder assembly after environmental tests by SEM internal probing

In this study, electrical characterization for lead-free materials in bump technology was developed and joint assemblies were thermally treated under temperature cycling tests. Measurements of sheet resistivity and contact resistance of intermetallic compounds (IMCs) in solder joints were conducted. Quantitative analysis and elemental redistribution of IMCs were obtained by field-emission electron probe microanalyzer. A scanning-electron microscopy internal probing system was introduced to evaluate electrical characteristics in IMCs after thermal treatments. To determine resistivity of IMCs, a novel method incorporating SELA-EM2 and a focused ion beam was developed to prepare the joint sample.