Measurements of metal/polymer interfacial fracture energy in microelectronics packaging

Using the T peel test, the interfacial fracture energies of flexible Cu/Cr/polyimide films were deduced from the direct measurement of root curvatures and the elastoplastic beam analysis. The T peel strength and peel angle were strongly affected by the Cu thickness and the biased RF plasma density of the polyimide pretreatment. As expected, the interfacial fracture energy between Cr and polyimide increased with the RF plasma power density, but was pretty much independent of the Cu film thickness, implying it has a close relationship with interfacial fracture toughness.