The Furukawa Electric Co., Ltd.

Nippon Steel & Sumikin Chemical Co., Ltd.

Koichi Hattori

Takeo Uno

Satoshi Fujisawa

Naoya Kuwasaki

Yuji Suzuki

Keiichi Kimura

Provided are a flexible circuit board with excellent bendability and durability against hard conditions particularly in a repeated bend portion having a small curvature radius, and a method of producing the same. The flexible circuit board includes a resin layer and a wiring formed of a metal foil and is used with a bend portion provided at least one position of the wiring. The metal foil is made of a metal having a cubic crystal structure, and a cross section of the wiring cut in a thickness direction from a ridge line in the bend portion forms a principal orientation on any one of planes within a range of (20 1 0) to (1 20 0) in a rotation direction from (100) to (110) with [001] set as a zone axis. The wiring is formed so that the metal foil is made of a metal having a cubic crystal structure, and that the ridge line in the bend portion has an angle in a range of 2.9&#xb0; to 87.1&#xb0; relative to one of fundamental crystal axes &#x3c;100&#x3e; in a surface of the metal foil.

Flexible circuit board and method for producing same and bend structure of flexible circuit board

Provided is an industrially excellent surface-treated copper foil which satisfies requirements for adhesiveness to an insulating resin such as polyimide, heat-resistant adhesiveness, chemical resistance and soft etching properties. Also provided is a method for producing a surface-treated copper foil which achieves a high adhesion strength between an insulating resin and the copper foil, shows high chemical resistance in circuit formation and sustains good soft etching properties after forming vias by laser-processing. A base copper foil is subjected to a roughening treatment to give a surface roughness (Rz) of 1.1 &#x3bc;m or below. On the roughened surface, an Ni&#x2014;Zn alloy layer is formed. The aforesaid roughening treatment is conducted in such a manner that the roughened surface comprises sharp-pointed convexes, which have a width of 0.3-0.8 &#x3bc;m, a height of 0.6-1.8 &#x3bc;m and an aspect ratio of 1.2-3.5, and the surface roughness (Rz) of said base copper foil is increased by 0.05-0.3 &#x3bc;m. The aforesaid Ni&#x2014;Zn alloy layer has a Zn content of 6-30 wt % and a Zn deposition amount of 0.08 mg/dmor more.

Surface-treated copper foil, method for producing same, and copper clad laminated board

In order to provide a flexible laminate circuit board using a surface treated copper foil satisfying all of a bonding strength of a copper foil with respect to polyimide, acid resistance, and etching property, in a flexible laminate circuit board formed by a copper foil on the surface of a polyimide resin layer, the copper foil is a surface treated copper foil formed by depositing an Ni&#x2014;Zn alloy onto at least one surface of a untreated copper foil, and the Zn deposition amount in the deposited Ni&#x2014;Zn alloy is 6% or more and 15% or less of the (Ni deposition amount+Zn deposition amount), and the Zn deposition amount is 0.08 mg/dmor more to provide a flexible copper clad laminate.

Growing community of inventors

Chiba, Japan

Koichi Hattori