Nippon Mining & Metals Co., Ltd.

Hironori Kobayashi

Masashi Kumagai

Katsuyuki Tsuchida

Ryu Murakami

The invention provides a two-layer flexible substrate free of surface defects and having excellent etching characteristics and adherence to a resist. The two-layer flexible substrate has a copper layer provided on one or both faces of an insulator film without using an adhesive, wherein the surface roughness (Ra) of the copper layer is 0.10 to 0.25 &#x3bc;m, and wherein the average crystal grain size [of copper] is no greater than 0.8 &#x3bc;m at 1 &#x3bc;m from the insulator film in the cross-section of the copper layer. Preferably, the insulator film is a polyimide film.

Two-layer flexible substrate

The object of the present invention is to obtain a low profile electrolytic copper foil with a low surface roughness at the rough surface side (opposite side from the glossy side) in the electrolytic copper foil manufacture using a cathode drum and, particularly, to obtain an electrolytic copper foil with excellent elongation and tensile strength that permits fine patterning. Another object is to obtain a copper electrolytic solution that allows uniform copper plating without pinholes on a 2-layer flexible substrate. This copper electrolytic solution contains, as an additive, a compound having the specific skeleton represented by General Formula (1) below which is obtained by an addition reaction in which water is added to a compound having in a molecule one or more epoxy groups: wherein A is an epoxy compound residue and n is an integer of 1 or more.

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Kitaibaraki, Japan

Hironori Kobayashi