EVALUATION OF ELASTOPLASTIC INTERFACIAL FRACTURE PARAMETERS IN SOLDER-COPPER BIMATERIAL USING MOIRE INTERFEROMETRY

An experimental investigation dealing with failure characterization of 63/37 solder-copper interfaces is presented. The method of moire inte rferometry is used for mapping elasto;plastic deformations in bimateri als subjected to predominantly tensile loading. A method for quantifyi ng the fracture parameter-the J-integral-using full-field measurement of crack opening displacements has been developed. A linear relationsh ip between crack tip opening displacements (CTOD) and the J-integral i s demonstrated. The crack growth resistance curve and hence crack init iation toughness J(c) value for the bimaterial is obtained. Full-field optical information has also suggested the possibility of using a sim pler method for the J-integral estimation using a single strain gage f or fracture testing of interfaces with large mismatch in this geometry .