Interfacial Delamination – Fatigue Crack Propagation Model
Research Report Highlight
Asymmetric Double Cantilever Beam testing was performed on epoxy molding compound and copper leadframe samples. Experimental and analytical approaches were combined to enable accurate monitoring of crack growth without requiring costly measuring equipment
Fatigue crack propagation for copper/epoxy molding compound interfaces is modeled in this work by conducting cyclic loading on double cantilever beam test specimens. The continued increase in mechanical compliance of test specimens as the crack propagates through hundreds of cycles is used to determine the crack length and thus, the crack growth rate per cycle which is used to determine the Paris’-law constants as a function of strain energy release rate range. When monotonic debonding testing is conducted, it is seen that the critical strain energy release rate initially increases with the crack length and then stabilizes demonstrating the increasing resistance for the epoxy/copper interface. When such an increasing R-curve is used to normalize the strain energy release rate range, it is observed that the Paris’-law constants can be determined with good consistency for a wide range of specimens over different crack lengths.