High-purity electrolytic copper and electrolytic refining method thereof

Patent metadata

Field	Value
Publication number	US-9783904-B2
Application number	US-201313915093-A
Country	US
Kind code	B2
Filing date	Jun 11, 2013
Priority date	Jun 14, 2012
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

This electrolytic refining method of high-purity electrolytic copper includes: performing electrolysis by using an electrolyte which includes a copper nitrate solution, a cathode made of stainless steel, and an anode made of copper so as to deposit high-purity electrolytic copper on the cathode.
(a) The electrolyte includes a mixture of polyethylene glycol and polyvinyl alcohol at a content of 20 ppm or more as an additive. (b) When a molecular weight of the polyethylene glycol is given as Z and a current density during the electrolysis is given as X (A/dm 2 ), the electrolysis is performed under conditions that fulfill the following relational expressions,

1000≦ Z ≦2000

1.2−( Z −1000)×0.0008≦ X ≦2.2−( Z −1000)×0.001.

First claim

The invention claimed is:

1. An electrolytic refining method of high-purity electrolytic copper, the method comprising:
performing electrolysis by using one electrolyte which includes a copper nitrate solution, a cathode made of stainless steel, and an anode made of copper so as to deposit high-purity electrolytic copper on the cathode,
wherein (a) the electrolyte includes a mixture of polyethylene glycol and polyvinyl alcohol at a content of 20 ppm or more as an additive,
(b) polyethylene glycol and polyvinyl alcohol are mixed to prepare a replenishment mixture thereof, and 500 mg or more of the replenishment mixture of polyethylene glycol and polyvinyl alcohol is added to the electrolyte per 1 kg of deposited copper in the electrolyte, and thereby, a content of the mixture of polyethylene glycol and polyvinyl alcohol in the electrolyte is maintained in a range of 20 ppm or more while the electrolysis is performed, and
(c) when a molecular weight of the polyethylene glycol is given as Z and a current density during the electrolysis is given as X (A/dm 2 ), the electrolysis is performed under conditions that fulfill the following relational expressions,
1000 ≦Z≦ 2000
1.2−( Z− 1000)×0.0008 ≦X≦ 2.2−( Z− 1000)×0.001.

2. The electrolytic refining method of high-purity electrolytic copper according to claim 1 ,
wherein the polyethylene glycol and the polyvinyl alcohol of the replenishment mixture are mixed at a volume ratio of polyethylene glycol:polyvinyl alcohol=4:1, and the mixture of polyethylene glycol and polyvinyl alcohol in the electrolyte has a volume ratio of polyethylene glycol:polyvinyl alcohol=4:1,
(a) a content of S in the deposited high-purity electrolytic copper is in a range of 0.01 ppm or less,
(b) a crystallite diameter on an electrolyte surface side of the deposited high-purity electrolytic copper is in a range of 400 nm or less,
(c) a crystallite diameter on a cathode side of the deposited high-purity electrolytic copper is in a range of 140 nm or more, and
(d) an orientation index of the deposited high-purity electrolytic copper on the cathode side fulfills the following relational expression,
an orientation index of (1, 1, 1) crystal face>an orientation index of (2, 2, 0) crystal face.

Assignees

• Mitsubishi Materials Corp

Inventors

• Watanabe Mami
• Nakaya Kiyotaka
• Kato Naoki

Classifications

• C25D3/38 Primary

  of copper · CPC title

• C25C1/12 Primary

  of copper · CPC title

• C25C7/06 Primary

  Operating or servicing · CPC title