Mitsui Minings & Melting Co., Ltd.

Shinya Hiraoka

Shinichi Obata

Toshiyuki Shimizu

Hideaki Matsushima

Koichi Miyake

Ayumu Tateoka

Sakiko Tomonaga

Hiroto Iida

Makoto Hosokawa

Tomoyuki Maeda

Misato Mizoguchi

Fumiaki Hosokoshi

An object of the present invention is to provide a copper foil excellent in softening resistance performance which reduces decrease in tensile strength after heat treatment at about 350&#xb0; C. to 400&#xb0; C. In order to achieve the object, a surface-treated copper foil provided with a rust-proofing treatment layer on both surfaces of a copper foil in which a rust-proofing treatment layer is constituted by zinc alloy, and the either rust-proofing treatment layer is a zinc alloy layer having zinc amount of 20 mg/mto 1,000 mg/m; and the copper foil contains one or two or more of small amount elements selected from carbon, sulfur, chlorine and nitrogen, and a sum amount thereof is 100 ppm or more is adopted.

Surface-treated copper foil

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Saitama, Japan

Shinya Hiraoka