Evaluation of Elasto-Plastic Interfacial Fracture Parameters in Solder-Copper Bimaterial Using Moiré Interferometry

Abstract

An experimental investigation dealing with failure characterization of 63/37 solder-copper interfaces is presented. The method of moiré interferometry is used for mapping elasto-plastic deformations in bimaterials subjected to predominantly tensile loading. A method for quantifying the fracture parameter—the J-integral—using full-field measurement of crack opening displacements has been developed. A linear relationship between crack tip opening displacements (CTOD) and the J-integral is demonstrated. The crack growth resistance curve and hence crack initiation toughness Jc value for the bimaterial is obtained. Full-field optical information has also suggested the possibility of using a simpler method for the J-integral estimation using a single strain gage for fracture testing of interfaces with large mismatch in this geometry.