Jx Nippon Mining Metals Corporation

Keisuke Yamanishi

Ryo Fukuchi

Kengo Kaminaga

Atsushi Miki

Yousuke Kobayashi

Provided is a rolled copper foil or electrolytic copper foil for an electronic circuit to be used for forming a circuit by etching, wherein the copper foil comprises a nickel or nickel alloy layer with a lower etching rate than copper formed on an etching side of the rolled copper foil or electrolytic copper foil, and a heat resistance layer composed of zinc or zinc alloy or its oxide formed on the nickel or nickel alloy layer. This invention aims to prevent sagging caused by the etching, to form a uniform circuit having the intended circuit width, and to shorten the time of forming a circuit by etching as much as possible, when forming a circuit by etching a copper foil of the copper-clad laminate; and also aims to make the thickness of the nickel or nickel alloy layer as thin as possible, to inhibit oxidation when exposed to heat, to prevent tarnish (discoloration) known as 'YAKE', to improve the etching properties in pattern etching, and to prevent the occurrence of short circuits and defects in the circuit width.

Rolled copper foil or electrolytic copper foil for electronic circuit, and method of forming electronic circuit using same

Provided is a rolled copper foil or electrolytic copper foil for an electronic circuit to be used for forming a circuit by etching, wherein the copper foil comprises a heat resistance layer composed of zinc or zinc alloy or its oxide formed on an etching side of the rolled copper foil or electrolytic copper foil, and a layer of nickel or nickel alloy, which is a metal or alloy with a lower etching rate than copper, formed on the heat resistance layer. This invention aims to prevent sagging caused by the etching, to form a uniform circuit having the intended circuit width, and to shorten the time of forming a circuit by etching as much as possible, when forming a circuit by etching a copper foil of the copper-clad laminate; and also aims to make the thickness of the nickel or nickel alloy layer as thin as possible, to inhibit oxidation when exposed to heat, to prevent tarnish (discoloration) known as 'YAKE', to improve the etching properties in pattern etching, and to prevent the occurrence of short circuits and defects in the circuit width.

Provided is a rolled copper or copper alloy foil having a roughened surface formed of fine copper particles, obtained by subjecting a rolled copper or copper alloy foil to roughening plating with a plating bath containing copper sulfate (Cu equivalent of 1 to 50 g/L), 1 to 150 g/L of sulfuric acid, and one or more additives selected among sodium octyl sulfate, sodium decyl sulfate, and sodium dodecyl sulfate under the conditions of a temperature of 20 to 50&#xb0; C. and a current density of 10 to 100 A/dm. The provided rolled copper or copper alloy foil subject to roughening is reduced in craters which are obvious defects unique to rolled copper or copper alloy foils having a roughened surface, has high strength, adhesive strength with the resin layer, acid resistance and anti-tin plating solution properties, high peel strength, favorable etching properties and gloss level, and also suits for use in producing a flexible printed wiring board capable of bearing a fine wiring pattern. Additionally provided is a method of roughening the rolled copper or copper alloy foil.

Rolled copper or copper alloy foil with roughened surface and method of roughening rolled copper or copper alloy foil

Provided is a method of forming an electronic circuit, wherein a nickel or nickel alloy layer is formed on an etching side of a rolled copper foil or an electrolytic copper foil, the rolled copper foil or the electrolytic copper foil is bonded to a resin substrate to obtain a copper-clad laminate, a resist pattern for forming a circuit is subsequently applied on the copper foil, any unwanted portion of the copper foil and the nickel or nickel alloy layer of the copper-clad laminate other than the portion to which the resist pattern was applied is removed using an etching solution of an aqueous ferric chloride, the resist is further removed, and soft etching is additionally performed in order to remove the remnant nickel or nickel alloy layer and thereby form a circuit in which the space between copper circuit lines is of a width that is double or more from the thickness of copper. This invention aims to form a circuit with a uniform circuit width, improve the etching properties in pattern etching, and prevent the occurrence of short circuits and defects in the circuit width.

Method of forming electronic circuit

A rolled copper or copper alloy foil having a roughened surface formed of fine copper particles is obtained by subjecting a rolled foil to roughening plating with a plating bath containing copper sulfate (Cu equivalent of 1 to 50 g/L), 1 to 150 g/L of sulfuric acid, and one or more additives selected among sodium octyl sulfate, sodium decyl sulfate, and sodium dodecyl sulfate under the conditions of temperature of 20 to 50&#xb0; C. and current density of 10 to 100 A/dm. The foil has reduced craters, which are defects unique to rolled foils having a roughened surface, has high strength, adhesive strength with the resin layer, acid resistance and anti-tin plating solution properties, high peel strength, favorable etching properties and gloss level, and is suitable for producing a flexible printed wiring board capable of bearing a fine wiring pattern. A method of roughening the rolled foil is also provided.

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Ibaraki, Japan

Keisuke Yamanishi