# US 5,705,082 A · Roughening of metal surfaces

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- Number: US 5,705,082 A
- Document ID: US5705082A
- Status: Granted
- Kind: A
- Application number: 08/378,525
- Filed: 1995-01-26
- Granted: 1998-01-06
- Earliest claimed: 1995-01-26
- Assignees: Chromalloy Gas Turbine Corporation
- Inventors: David Hinson
- Web page: https://patentgrep.com/patent/US5705082A

## CPC

- H05K 3/383: {by microetching}
- C23F 1/02: Local etching
- C23F 1/26: for etching refractory metals
- H05K 2201/0116: Porous, e.g. foam
- H05K 2201/0166: Polymeric layer used for special processing, e.g. resist for etching insulating material or photoresist used as a mask during plasma etching
- H05K 2201/0373: Conductors having a fine structure, e.g. providing a plurality of contact points with a structured tool
- H05K 2203/0769: Dissolving insulating materials, e.g. coatings, not used for developing resist after exposure
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- 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

## Abstract

A process for roughening a metal surface is provided comprising applying a coating to the metal surface wherein the coating is a temporary barrier to an etchant attacking the metal surface and the coating is susceptible to the etchant gradually removing the coating, and then etching the coated metal surface with an aqueous bath containing the etchant effective to produce a roughened metal surface.

## Claims

### Claim 1

Process for roughening a metal surface comprising:
applying to the metal surface a coating which is a temporary barrier to an etchant attacking the metal surface, wherein the coating is susceptible to being gradually removed by the etchant and to being erratically penetrated by the etchant causing irregular action between the etchant and the metal; and
etching the coated metal surface with an aqueous bath containing the etchant effective to produce a roughened metal surface.

### Claim 2 (depends on 1)

Process of claim 1 wherein the etchant is an acid.

### Claim 3 (depends on 2)

Process of claim 2 wherein the metal surface is of titanium or a titanium alloy.

### Claim 4 (depends on 3)

Process of claim 3 wherein the acid bath comprises hydrofluoric acid.

### Claim 5 (depends on 4)

Process of claim 4 wherein the acid bath further comprises an acid selected from the group consisting of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid and mixtures thereof.

### Claim 6 (depends on 4)

Process of claim 4 wherein the acid bath further comprises nitric acid.

### Claim 7 (depends on 1)

Process of claim 1 wherein the coating is a polymer composition.

### Claim 8 (depends on 6)

Process of claim 6 wherein the coating is a polymer composition.

### Claim 9 (depends on 8)

Process of claim 8 further comprising drying and curing the polymer composition.

### Claim 10 (depends on 9)

Process of claim 9 wherein the polymer composition is a heat curable adhesive.

### Claim 11 (depends on 9)

Process of claim 9 wherein etching is continued until the surface roughness is at least 150 microinches.

### Claim 12 (depends on 11)

Process of claim 11 wherein etching is continued until the surface roughness is at least 150 average surface peaks per inch.

### Claim 13 (depends on 12)

Process of claim 12 further comprising rinsing the roughened metal surface and removing any residual coating from the metal surface.

### Claim 14 (depends on 13)

Process of claim 13 further comprising prior to etching applying a mask to that portion of the metal surface which is not to be roughened.

### Claim 15 (depends on 6)

Process of claim 6 wherein the acid bath contains 1 to 20% by volume hydrofluoric acid and 1 to 20% by volume of nitric acid.

### Claim 16 (depends on 10)

Process of claim 10 wherein the acid bath contains 5 to 10% by volume of hydrofluoric acid and 5 to 16% by volume of nitric acid.

### Claim 17 (depends on 16)

Process of claim 16 wherein etching is carded out for 1 to 20 minutes at temperatures in the range of 70.degree.-110.degree. F.