Fatigue Crack Propagation Behavior in Surface Film-Bonded Materials with Resin Bonding layer

摘要

Surface film-bonded materials with resin interlayer are often used in electronic parts, fatigue properties of which have to be discussed in order to maintain the expected electronic function without fracture during operating. In this study, pure copper and commercial grade iron films with the thickness of 100 mum were bonded to the surface of carbon steel base plate by epoxy resin adhesive or by diffusion. As a result of fatigue testing, there was a tendency for the epoxy-bonding layer to restrict fatigue crack propagation from the surface film to inner base plate. In addition, the epoxy-bonded iron film had a compressive residual stress and also caused smaller stress amplitude in the inner base plate between films, so that the fatigue life of the epoxy-bonded plate was longer for the iron film than for the copper film. The fatigue crack propagation rate, da/dN, for all the film-bonded plates was expressed by a power law of the measured crack opening displacement range, DELTA PHI_(250), as well as for several metal base plates, although the fatigue crack on the epoxy-bonded film propagated at the low value of DELTA PHI_(250) in which the fatigue crack did not propagate for the diffusion-bonded plate and the base plates.