電子部品用銅はくの降伏および破壊特性

抄録

Mechanical properties under uniaxial and equi-biaxial tensions are examined for electronic copper foils and sheets ranging from 5 μm to 1 mm in thickness. A hydraulic microbulge test is proposed for the equi-biaxial tension applicable to very thin metal foils, and its validity is confirmed by computer simulation based on the Bassani yield function. The yield stresses in both the uniaxial and equi-biaxial tests are dependent on the grain size, but not on thickness. The conventional yield criteria are shown to be applicable even to very thin foils as well as to sheets with usual thickness. However, the fracture mechanism varies according to the thickness, and thus, the limit strain and ductility of foils become markedly low.