Importance

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Abstract

A high-performance bonding wire that is suitable for semiconductor mounting technology, such as stacked chip bonding, thinning, and fine pitch mounting, where wire lean (leaning) at an upright position of a ball and spring failure can be suppressed and loop linearity and loop height stability are excellent. This bonding wire for a semiconductor device includes a core material made of a conductive metal, and a skin layer formed on the core material and containing a metal different from the core material as a main component; wherein a relationship between an average size (a) of crystal grains in the skin layer on a wire surface along a wire circumferential direction and an average size (b) of crystal grains in the core material on a normal cross section, the normal cross section being a cross section normal to a wire axis, satisfies an inequality of a/b≦0.7.

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First Claim