Silver-coated copper powder and method for producing same

Patent metadata

Field	Value
Publication number	US-2018272425-A1
Application number	US-201615542464-A
Country	US
Kind code	A1
Filing date	Jan 6, 2016
Priority date	Jan 13, 2015
Publication date	Sep 27, 2018
Grant date	—

Abstract

A silver-coated copper powder obtained by coating the surface of a copper powder, which is obtained by the atomizing method or the like, with 5 wt % or more (with respect to the silver-coated copper powder) of a silver containing layer of silver or a silver compound, is added to a silver supporting solution of a potassium silver cyanide solution (or a potassium silver cyanide solution containing at least one selected from the group consisting of potassium pyrophosphate, boric acid, tripotassium citrate monohydrate, anhydrous citric acid and L-aspartic acid) to cause 0.01 wt % or more (with respect to the silver-coated copper powder) of silver to be supported on the surface of the copper powder coated with the silver containing layer.

First claim

1 . A method for producing a silver-coated copper powder, the method comprising the steps of:
preparing a copper powder, the surface of which is coated with a silver containing layer; and adding the copper powder to a silver supporting solution to cause silver to be supported on the surface of the copper powder coated with the silver containing layer.

2 . A method for producing a silver-coated copper powder as set forth in claim 1 , wherein said surface, on which silver is caused to be supported, is an exposed surface of said copper powder coated with said silver containing layer.

3 . A method for producing a silver-coated copper powder as set forth in claim 1 , wherein said silver containing layer is a layer of silver or a silver compound.

4 . A method for producing a silver-coated copper powder as set forth in claim 1 , wherein the amount of said silver containing layer with respect to said silver-coated copper powder is not less than 5% by weight.

5 . A method for producing a silver-coated copper powder as set forth in claim 1 , wherein the amount of the supported silver with respect to said silver-coated copper powder is not less than 0.01% by weight.

6 . A method for producing a silver-coated copper powder as set forth in claim 1 , wherein said silver supporting solution comprises a potassium silver cyanide solution.

7 . A method for producing a silver-coated copper powder as set forth in claim 6 , wherein said potassium silver cyanide solution contains at least one selected from the group consisting of potassium pyrophosphate, boric acid, tripotassium citrate monohydrate, anhydrous citric acid and L-aspartic acid.

8 . A method for producing a silver-coated copper powder as set forth in claim 1 , wherein a particle diameter (D 50 diameter) corresponding to 50% of accumulation in cumulative distribution of said copper powder, which is measured by a laser diffraction particle size analyzer, is in the range of from 0.1 μm to 15 μm.

9 . A silver-coated copper powder,
wherein silver is supported on an exposed portion of a surface of a copper powder coated with a silver containing layer, and wherein two exothermic peaks appear when the silver-coated copper powder is heated to raise the temperature thereof from room temperature to 400° C. in the atmosphere by means of a thermogravimetry differential thermal analyzer.

10 . A silver-coated copper powder as set forth in claim 9 , wherein one of said two exothermic peaks is a main peak which has an exothermic peak temperature of 330 to 370° C., and the other exothermic peak is a sub-peak which has an exothermic peak temperature of 230 to 270° C.

11 . A silver-coated copper powder,
wherein silver is supported on an exposed portion of a surface of a copper powder coated with a silver containing layer, and wherein the percentage of increase of the weight of the silver-coated copper powder is 0.3% or less at 250° C. and 1.0% or less at 300° C., respectively, when the silver-coated copper powder is heated to raise the temperature thereof from room temperature to 400° C. in the atmosphere by means of a thermogravimetry differential thermal analyzer.

12 . A silver-coated copper powder as set forth in claim 9 , wherein said silver containing layer is a layer of silver or a silver compound.

13 . A silver-coated copper powder as set forth in claim 9 , wherein the amount of said silver containing layer with respect to said silver-coated copper powder is not less than 5% by weight.

14 . A silver-coated copper powder as set forth in claim 9 , wherein the amount of the supported silver with respect to said silver-coated copper powder is not less than 0.01% by weight.

15 . A silver-coated copper powder as set forth in claim 9 , wherein a particle diameter (D 50 diameter) corresponding to 50% of accumulation in cumulative distribution of said copper powder, which is measured by a laser diffraction particle size analyzer, is in the range of from 0.1 μm to 15 μm.

16 . A silver-coated copper powder as set forth in claim 9 , wherein the amount of cyanogen in said silver-coated copper powder is in the range of from 10 ppm to 3000 ppm.

17 . A silver-coated copper powder as set forth in claim 9 , wherein the content of each of carbon and nitrogen in said silver-coated copper powder is not less than 0.04% by weight.

18 . An electrically conductive paste wherein a silver powder as set forth in claim 9 is used as an electric conductor.

19 . An electrically conductive paste comprising:
a solvent; a resin; and a silver powder as set forth in claim 9 as an electrically conductive powder.

20 . A method for producing an electrode for solar cell, the method comprising the steps of:
applying an electrically conductive paste as set forth in claim 18 , on a substrate; and curing the electrically conductive paste to form an electrode on the surface of the substrate.

Assignees

• Dowa Electronics Materials Co Ltd

Inventors

• Nogami Noriaki
• Kamiga Hiroshi

Classifications

• H01B1/02

  mainly consisting of metals or alloys · CPC title

• H05K2201/0218

  Composite particles, i.e. first metal coated with second metal · CPC title

• H01B1/22

  the conductive material comprising metals or alloys · CPC title

• H05K1/092

  Dispersed materials, e.g. conductive pastes or inks · CPC title

• B22F2301/255

  Silver or gold · CPC title