Method for producing high-purity electrolytic copper

Patent metadata

Field	Value
Publication number	US-11753733-B2
Application number	US-201816617574-A
Country	US
Kind code	B2
Filing date	Jun 1, 2018
Priority date	Jun 1, 2017
Publication date	Sep 12, 2023
Grant date	Sep 12, 2023

Abstract

In a method for producing high-purity electrolytic copper, a first additive (A) containing an aromatic ring of a hydrophobic group and a polyoxyalkylene group of a hydrophilic group, a second additive (B) formed of polyvinyl alcohols, and a third additive (C) formed of tetrazoles are added to a copper electrolyte, copper electrolysis is performed by controlling each concentration of the first additive (A), the second additive (B), and the third additive (C), a current density and a bath temperature, and accordingly, electrolytic copper in which a concentration of Ag is less than 0.2 mass ppm, a concentration of S is less than 0.07 mass ppm, a concentration of all impurities is less than 0.2 mass ppm, and an area ratio of crystal grains having an average crystal grain misorientation (referred to as a GOS value) exceeding 2.5° is 10% or less is obtained.

First claim

The invention claimed is:

1. A method for producing high-purity electrolytic copper, comprising:
Preparing a copper electrolyte using copper sulfate;
adding a first additive (A) containing an aromatic ring of a hydrophobic group and a polyoxyalkylene group of a hydrophilic group, a second additive (B) formed of polyvinyl alcohols, and a third additive (C) formed of tetrazoles to the copper electrolyte; and
performing copper electrolysis by setting a concentration of the first additive (A) to be 10 mg/L to 500 mg/L, a concentration of the second additive (B) to be 1 mg/L to 100 mg/L, a concentration of the third additive (C) to be 0.01 mg/L to 5 mg/L, a concentration ratio (B/A) of the second additive (B) to the first additive (A) to be 0.1 to 0.8, and a concentration ratio (C/A) of the third additive (C) to the first additive (A) to be greater than 0 and 0.7 or less, and controlling a current density and a bath temperature to produce electrolytic copper in which a concentration of Ag is less than 0.2 mass ppm, a concentration of S is less than 0.1 mass ppm, a concentration of all impurities is less than 0.2 mass ppm, and an area ratio of crystal grains having an average crystal grain misorientation (referred to as a GOS value) exceeding 2.5º is 10% or less, wherein
the third additive (C) is one or more of the tetrazoles selected from a group consisting of 5-methyl-1H-tetrazole and 5-phenyl-1H-tetrazole.

2. The method for producing high-purity electrolytic copper according to claim 1 , comprising:
performing copper electrolysis by setting the current density to be 150 A/m 2 to 190 A/m 2 and the bath temperature to be 30° C. to 35° C. to produce electrolytic copper in which the concentration of Ag is less than 0.15 mass ppm, the concentration of S is less than 0.07 mass ppm, the concentration of all impurities is less than 0.2 mass ppm, and the area ratio of crystal grains having an average crystal grain misorientation (GOS value) exceeding 2.5º is 10% or less.

3. The method for producing high-purity electrolytic copper according to claim 1 , comprising:
setting the concentration of the first additive (A) to be 40 mg/L to 200 mg/L, the concentration of the second additive (B) to be 10 mg/L to 50 mg/L, the concentration of the third additive (C) to be 0.1 mg/L to 5 mg/L, the concentration ratio (B/A) of the second additive (B) to the first additive (A) to be 0.1 to 0.65, and the concentration ratio (C/A) of the third additive (C) to the first additive (A) to be 0.001 to 0.5 to produce electrolytic copper in which the concentration of Ag is less than 0.1 mass ppm, the concentration of S is less than 0.02 mass ppm, the concentration of all impurities is less than 0.1 mass ppm, and the area ratio of crystal grains having an average crystal grain misorientation (GOS value) exceeding 2.5º is 8% or less.

4. The method for producing high-purity electrolytic copper according to claim 1 , comprising:
setting the concentration of the second additive (B) to be 10 mg/L to 50 mg/L, the concentration of the third additive (C) to be 1 mg/L to 5 mg/L, the concentration ratio (B/A) of the second additive (B) to the first additive (A) to be 0.13 to 0.4, and the concentration ratio (C/A) of the third additive (C) to the first additive (A) to be 0.005 to 0.10 to produce electrolytic copper in which the concentration of Ag is less than 0.08 mass ppm, the concentration of S is less than 0.01 mass ppm, the concentration of all impurities is less than 0.1 mass ppm, and the area ratio of crystal grains having an average crystal grain misorientation (GOS value) exceeding 2.5º is 5% or less.

5. The method for producing high-purity electrolytic copper according to claim 2 , comprising:
setting the concentration of the first additive (A) to be 40 mg/L to 200 mg/L, the concentration of the second additive (B) to be 10 mg/L to 50 mg/L, the concentration of the third additive (C) to be 0.1 mg/L to 5 mg/L, the concentration ratio (B/A) of the second additive (B) to the first additive (A) to be 0.1 to 0.65, and the concentration ratio (C/A) of the third additive (C) to the first additive (A) to be 0.001 to 0.5 to produce electrolytic copper in which the concentration of Ag is less than 0.1 mass ppm, the concentration of S is less than 0.02 mass ppm, the concentration of all impurities is less than 0.1 mass ppm, and the area ratio of crystal grains having an average crystal grain misorientation (GOS value) exceeding 2.5º is 8% or less.

6. The method for producing high-purity electrolytic copper according to claim 2 , comprising:
setting the concentration of the second additive (B) to be 10 mg/L to 50 mg/L, the concentration of the third additive (C) to be 1 mg/L to 5 mg/L, the concentration ratio (B/A) of the second additive (B) to the first additive (A) to be 0.13 to 0.4, and the concentration ratio (C/A) of the third additive (C) to the first additive (A) to be 0.005 to 0.10 to produce electrolytic copper in which the concentration of Ag is less than 0.08 mass ppm, the concentration of S is less than 0.01 mass ppm, the concentration of all impurities is less than 0.1 mass ppm, and the area ratio of crystal grains having an average crystal grain misorientation (GOS value) exceeding 2.5º is 5% or less.

7. The method for producing high-purity electrolytic copper according to claim 2 , wherein the current density is 175 A/m 2 to 190 A/m 2 .

8. The method for producing high-purity electrolytic copper according to claim 1 , the GOS value is represented by an expression (1),

G
⁢
OS

=

(

∑

i
,

j
-
1

n

α

i
⁢

j
⁡
(

i
≠
j

)

)

/

n
⁡
(

n
-
1

)

(
1
)

wherein, in the expression (1), a pixel number in the same crystal grain is n, respective numbers of different pixels in the same crystal grain are i and j (1≤i, j≤n), and a crystal misorientation obtained from a crystal orienta

Assignees

• Mitsubishi Materials Corp

Inventors

• Tarutani Yoshie
• Kubota Kenji
• Nakaya Kiyotaka
• Arai Isao

Classifications

• C22C9/00 Primary

  Alloys based on copper · CPC title

• C25C1/12 Primary

  of copper · CPC title