Investigation of interfacial behavior of a Si-epoxy-FR4 structure under thermal testing using moire interferometry

摘要

The interfacial behavior of a flip chip structure under thermal testing was investigated using real-time moire interferometry. The maximum shear strain occurred at the silicon-epoxy interface. The shear strain variation increased significantly along the interface, with the maximum shear concentration occurring at the edge of the specimen. The creep effect was more dominant in the FR4-epoxy interface. To characterize the behavior of the interfacial crack, stress intensity factors and the strain energy release rate in the vicinity of the crack tip were used to conduct a qualitative study. A sharp strain gradient occurred at the crack tip. The stress intensity factors were dependent on temperature.