Non-cyanide copper-zinc electroplating bath, method of surface treatment of copper foil for printed wiring board using the same and copper foil for printed wiring board

• US 5,534,128 A
• Filed: 02/24/1995
• Issued: 07/09/1996
• Est. Priority Date: 02/24/1994
• Status: Expired due to Term

• Current Assignee: Nippon Denkai Ltd. (Resonac Holdings Corp.)
• Original Assignee: Nippon Denkai Ltd. (Resonac Holdings Corp.)
• Inventors: Aso, Kazuyoshi, Kobayashi, Katsumi, Yamagishi, Takeshi, Noguchi, Masami
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Wong, Edna
• Application Number:
  US08/393,496
• Time in Patent Office: 501 Days
• Field of Search: 205/176, 205/177, 205/178, 205/182, 205/191, 205/194, 205/196, 205/240, 205/244, 106/1.05, 106/1.13, 106/1.17, 106/1.18, 106/1.26, 106/1.29
• US Class Current: 205/176
• CPC Class Codes: C25D 3/58 containing more than 50% by weight of copper
• CPC Class Codes: H05K 2201/0323 Carbon
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 2201/2063 mixed adhesion layer containing metallic/inorganic and polymeric materials
• CPC Class Codes: H05K 2203/0307 Providing micro- or nanometer scale roughness on a metal surface, e.g. by plating of nodules or dendrites
• CPC Class Codes: H05K 2203/0723 Electroplating, e.g. finish plating
• CPC Class Codes: H05K 3/384 by plating
• CPC Class Codes: Y10S 428/935 Electroplating
• CPC Class Codes: Y10T 428/12438 Composite
• CPC Class Codes: Y10T 428/12549 Adjacent to each other
• CPC Class Codes: Y10T 428/12569 Synthetic resin
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12792 Zn-base component
• CPC Class Codes: Y10T 428/1291 Next to Co-, Cu-, or Ni-base component

Abstract

A copper foil for a printed wiring board which has a carbon-containing copper-zinc coating comprising 40 to 90 atomic % of copper, 5 to 50 atomic % of zinc and 0.1 to 20 atomic % of carbon is produced by dipping a copper foil in a non-cyanide copper-zinc electroplating bath containing a copper salt, a zinc salt, a hydroxycarboxylic acid or a salt thereof, an aliphatic dicarboxylic acid or a salt thereof and a thiocyanic acid or a salt thereof, and carrying out electrolysis in the non-cyanide copper-zinc electroplating bath using the copper foil as a cathode to form on at least one surface of the copper foil a carbon-containing copper-zinc coating.

Claims

1. A non-cyanide copper-zinc electroplating bath comprising an aqueous solution containing 5 to 60 g/l of a copper salt, 2 to 30 g/l of a zinc salt, 30 to 120 g/l of a hydroxycarboxylic acid or salt thereof, an aliphatic dicarboxylic acid or a sodium salt or a potassium salt thereof, and a thiocyanic acid or a salt thereof.

2. The non-cyanide copper-zinc electroplating bath of claim 1, wherein the aliphatic dicarboxylic acid or salt thereof is in a concentration of 20 to 120 g/l and the thiocyanic acid or salt thereof is in a concentration of 1 to 20 g/l.

3. The non-cyanide copper-zinc electroplating bath of claim 1 or claim 2, wherein the copper salt is copper sulfate, the zinc salt is zinc sulfate, the salt of the hydroxycarboxylic acid is sodium glucoheptonate, the salt of the aliphatic dicarboxylic acid is potassium oxalate, and the salt of the thiocyanic acid is potassium thiocyanate.

4. A method of surface treatment of a copper foil for a printed wiring board comprising dipping a copper foil in a non-cyanide copper-zinc electroplating bath which comprises an aqueous solution containing a copper salt, a zinc salt, a hydroxycarboxylic acid or a salt thereof, an aliphatic dicarboxylic acid or a salt thereof and a thiocyanic acid or a salt thereof, and carrying out electrolysis in the non-cyanide copper-zinc electroplating bath using the copper foil as a cathode to form on at least one surface of the copper foil a carbon-containing copper-zinc coating.

5. The method of claim 4, wherein, in the non-cyanide electroplating bath, the copper salt is in a concentration of 5 to 60 g/l, the zinc salt is in a concentration of 2 to 30 g/l, the hydroxycarboxylic acid or the salt thereof is in a concentration of 20 to 120 g/l, the aliphatic dicarboxylic acid or the salt thereof is in a concentration of 20 to 120 g/l and the thiocyanic acid or the salt thereof is in a concentration of 1 to 20 g/l.

6. The method of claim 4 or 5, wherein the copper salt is copper sulfate, the zinc salt is zinc sulfate, the salt of the hydroxycarboxylic acid is sodium glucoheptonate, the salt of the aliphatic dicarboxylic acid is potassium oxalate, and the salt of the thiocyanic acid is potassium thiocyanate.

7. A method of surface treatment of a copper foil for a printed wiring board comprising dipping a copper foil in a non-cyanide copper-zinc electroplating bath which comprises an aqueous solution containing a copper salt, a zinc salt, a hydroxycarboxylic acid or a salt thereof, an aliphatic dicarboxylic acid or a salt thereof and a thiocyanic acid or a salt thereof, carrying out electrolysis in the non-cyanide copper-zinc electroplating bath using the copper foil as a cathode to form on at least one surface of the copper foil a carbon-containing copper-zinc coating, and carrying out electrolysis in an aqueous solution containing hexavalent chromium ion using the copper foil as a cathode to form on the carbon-containing copper-zinc coating a chromate-treatment coating.

8. The method of claim 7, wherein, in the non-cyanide copper-zinc electroplating bath, the copper salt is in a concentration of 5 to 60 g/l, the zinc salt is in a concentration of 2 to 30 g/l, the hydroxycarboxylic acid or the salt thereof is in a concentration of 20 to 120 g/l, the aliphatic dicarboxylic acid or the salt thereof is in a concentration of 20 to 120 g/l and the thiocyanic acid or the salt thereof is in a concentration of 1 to 20 g/l.

9. The method of claim 7 or 8, wherein the copper salt is copper sulfate, the zinc salt is zinc sulfate, the salt of the hydroxycarboxylic acid is sodium glucoheptonate, the salt of the aliphatic dicarboxylic acid is potassium oxalate, and the salt of the thiocyanic acid is potassium thiocyanate.

10. A method of surface treatment of a copper foil for a printed wiring board comprising dipping a copper foil in a non-cyanide copper-zinc electroplating bath which comprises an aqueous solution containing a copper salt, a zinc salt, a hydroxycarboxylic acid or a salt thereof, an aliphatic dicarboxylic acid or a salt thereof and a thiocyanic acid or a salt thereof, carrying out electrolysis in the non-cyanide copper-zinc electroplating bath using the copper foil as a cathode to form on at least one surface of the copper foil a carbon-containing copper-zinc coating, carrying out electrolysis in an aqueous solution containing hexavalent chromium ion by using the copper foil as a cathode to form on the carbon-containing copper-zinc coating a chromate-treatment coating, and applying an aqueous solution of a silane coupling agent on the chromate-treatment coating to form a silane coupling agent coating.

11. The method of claim 10, wherein, in the non-cyanide copper-zinc electroplating bath, the copper salt is in a concentration of 5 to 60 g/l, the zinc salt is in a concentration of 2 to 30 g/l, the hydroxycarboxylic acid or the salt thereof is in a concentration of 20 to 120 g/l, the aliphatic dicarboxylic acid or the salt thereof is in a concentration of 20 to 120 g/l and the thiocyanic acid or the salt thereof is in a concentration of 1 to 20 g/l.

12. The method of claim 10 or 11, wherein the copper salt is copper sulfate, the zinc salt is zinc sulfate, the salt of the hydroxycarboxylic acid is sodium glucoheptonate, the salt of the aliphatic dicarboxylic acid is potassium oxalate, and the salt of the thiocyanic acid is potassium thiocyanate.