# US 5,344,503 A · Method of preventing oxidation of copper powder

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- Number: US 5,344,503 A
- Document ID: US5344503A
- Status: Granted
- Kind: A
- Application number: 08/003,637
- Filed: 1993-01-13
- Granted: 1994-09-06
- Earliest claimed: 1992-01-13
- Assignees: Murata Manufacturing Co., Ltd.
- Inventors: Shizuharu Watanabe; Shuji Mushimoto
- Web page: https://patentgrep.com/patent/US5344503A

## CPC

- H01B 1/026: {Alloys based on copper}
- B22F 1/145: Chemical treatment, e.g. passivation or decarburisation
- H05K 1/092: {Dispersed materials, e.g. conductive pastes or inks}
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

A method of preventing oxidation of copper powder which comprises the steps of: mixing copper powder, boric acid, and a solvent to form a mixture; and drying the mixture to evaporate the solvent, the boric acid being used in such an amount that the amount of boron atoms present in the copper powder after the drying step is from 0.01 to 0.1% by weight based on the weight of the copper powder, the solvent being selected from the group consisting of ketone solvents, hydrocarbon solvents and aromatic solvents, and being used in such an amount that the boric acid concentration of the mixture is not higher than the saturated concentration of boric acid.

## Claims

### Claim 1

A method of preventing oxidation of copper powder which comprises the steps of:
mixing copper powder, boric acid, and a solvent to form a mixture; and
drying said mixture to evaporate said solvent,
said boric acid being used in such an amount that the amount of boron atoms present in said copper powder after said drying step is from 0.01 to 0.1% by weight based on the weight of said copper powder,
said solvent being selected from the group consisting of ketone solvents, hydrocarbon solvents and aromatic solvents, and being used in such an amount that the boric acid concentration of said mixture is not higher than the saturated concentration of boric acid.

### Claim 2 (depends on 1)

A method as claimed in claim 1, wherein said drying step is conducted at a temperature of 260.degree. C. or less.

### Claim 3 (depends on 1)

A method as claimed in claim 1, wherein said solvent is a ketone solvent.

### Claim 4 (depends on 3)

A method as claimed in claim 3, wherein said ketone solvent is selected from the group consisting of acetone, methyl ethyl ketone, and diethyle ketone.

### Claim 5 (depends on 4)

A method as claimed in claim 4, wherein said ketone solvent is acetone.

### Claim 6 (depends on 1)

A method as claimed in claim 1, wherein said solvent is a hydrocarbon solvent.

### Claim 7 (depends on 6)

A method as claimed in claim 6, wherein said hydrocarbon solvent is selected from the group consisting of pentane, hexane, and heptane.

### Claim 8 (depends on 1)

A method as claimed in claim 1, wherein said solvent is an aromatic solvent.

### Claim 9 (depends on 8)

A method as claimed in claim 8, wherein said aromatic solvent is selected from the group consisting of benzene, xylene, and toluene.