EFFECTS OF INTERLAYER RESIN BONDING ON FATIGUE CRACK INITIATION/PROPAGATION IN LAMINATE MATERIALS WITH A SURFACE LAYER OF COPPER FILM

摘要

As model specimens to examine the effects of interlayer resin bonding on fatigue properties in laminate materials with a surface film, pure copper films with a thickness of 100μm and 50μm were bonded with epoxy resin to steel base plates. The fatigue crack propagation from the notch root of the specimen was slower for the epoxy-bonded film than for the base specimen, because the epoxy bonding interlayer restricted crack propagation from the surface film to the inner base plate. On the epoxy-bonded film, however, many fatigue cracks initiated at multiple sites sufficiently away from the notch root, and propagated only on the surface copper film. In addition, the number of these multiple fatigue cracks, caused mostly at the site of the annealing twin boundaries, was larger on the surface copper film with a thickness of 100μm than 50μm.