# US 5,700,389 A · Etching solution for copper or copper alloy

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- Number: US 5,700,389 A
- Document ID: US5700389A
- Status: Granted
- Kind: A
- Application number: 08/510,299
- Filed: 1995-08-02
- Granted: 1997-12-23
- Earliest claimed: 1994-08-12
- Assignees: Mec Company Ltd.
- Inventors: Toshiko Nakagawa
- Web page: https://patentgrep.com/patent/US5700389A

## CPC

- C23G 1/103: {copper or alloys of copper}
- C23F 1/18: for etching copper or alloys thereof
- H05K 3/383: {by microetching}
- H05K 3/064: {Photoresists}
- H05K 3/28: Applying non-metallic protective coatings {(H05K3/0091 takes precedence; methods for intermediate insulating layers for build-up multilayer circuits H05K3/4673)}
- H05K 2203/0796: Oxidant in aqueous solution, e.g. permanganate
- H05K 2203/124: Heterocyclic organic compounds, e.g. azole, furan
- C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

An etching solution for copper or copper alloys comprising, (a) sulfuric acid, (b) a persulfate, (c) at least one compound selected from imidazole, imidazole derivatives, pyridine derivatives, triazine, and triazine derivatives, and (d) water. The etching solution exhibits a high etching speed and does not oxidize the copper surfaces after etching.

## Claims

### Claim 1

An etching solution for copper or copper alloys comprising:
(a) sulfuric acid,
(b) a persulfate,
(c) at least one compound selected from the group consisting of imidazole, imidazole derivatives, pyridine derivatives in which the 2-position or 4-position thereof is substituted with an alkyl group, an amino group or a carboxyl group, triazine, and triazine derivatives,
(d) water, and
(e) amidosulfuric acid or an aliphatic sulfonic acid.

### Claim 2 (depends on 1)

The etching solution according to claim 1, wherein component (c) is imidazole or an imidazole derivative.

### Claim 3 (depends on 2)

The etching solution according to claim 2, wherein component (c) is an imidazole derivative and said imidazole derivative is selected from the group consisting of 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-aminoimidazole, 4-methylimidazole, 4-ethylimidazole and 4-propylimidazole.

### Claim 4 (depends on 1)

The etching solution according to claim 1, wherein component (c) is triazine or a triazine derivative.

### Claim 5 (depends on 4)

The etching solution according to claim 4, wherein component (c) is a triazine derivative and said triazine derivative is selected from the group consisting of 2,4-diamino-6-methyltriazine and 2,4-diamino-6-ethyltriazine.

### Claim 6 (depends on 1)

The etching solution according to claim 1, wherein component (c) is a pyridine derivative selected from the group consisting of 2-methylpyridine, 2-aminopyridine, 2-aminomethylpyridine, 2-carboxypyridine, 4-methylpyridine, 4-aminopyridine and 4-aminomethylpyridine.

### Claim 7 (depends on 1)

The etching solution according to claim 1, wherein component (e) is an aliphatic sulfonic acid and said aliphatic sulfonic acid is selected from the group consisting of methylsulfonic acid, aminosulfonic acid and aminomethylsulfonic acid.

### Claim 8 (depends on 1)

The etching solution according to claim 1, wherein component (c) is present in an amount of 0.1-10 g/l of etching solution.

### Claim 9 (depends on 8)

The etching solution according to claim 8, wherein component (c) is present in an amount of 0.5-10 g/l of etching solution.

### Claim 10 (depends on 1)

The etching solution according to claim 1, wherein component (e) is present in an amount of 1-100 g/l of etching solution.

### Claim 11 (depends on 10)

The etching solution according to claim 10, wherein component (e) is present in an amount of 1-50 g/l of etching solution.

### Claim 12 (depends on 1)

The etching solution according to claim 1, wherein said persulfate is present in an amount of 50-250 g/l of etching solution.

### Claim 13 (depends on 1)

The etching solution according to claim 1, further comprising a fluorine-containing surfactant or nonionic surfactant.