Microcantilever Fracture Testing of Intermetallic Cu3Sn in Lead-Free Solder Interconnects
Driven by legislation and the abolishment of harmful and hazardous lead-containing solders, lead-free replacement materials are in continuous development. Assessment of the mechanical properties of intermetallic phases such as Cu3Sn that evolve at the interface between solder and copper metalization is crucial to predict performance and meet the high reliability demands in typical application fields of microelectronics. While representative material parameters and fracture properties are required to assess mechanical behavior, indentation-based testing produces different results depending on the sample type. In this work, focused ion beam machined cantilevers were used to unravel the impact of microstructure on the fracture behavior of Sn-Ag-Cu lead-free solder joints. Fracture testing on notched cantilevers showed brittle fracture for Cu3Sn. Unnotched samples allowed measurement of the fracture stress, to estimate the critical defect size in unnotched Cu3Sn microcantilevers.
KeywordsLead-free solder Cu3Sn small-scale testing fracture toughness
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This work was jointly funded by the Austrian Research Promotion Agency (FFG, Project No. 854247) and the Carinthian Economic Promotion Fund (KWF, Contract KWF-1521/28101/40388).
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