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Flaky Copper Powder, Method For Producing The Same, And Conductive Paste

Inactive Publication Date: 2007-09-13
MITSUI MINING & SMELTING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0031] The flaky copper powder is free from compression deformation process. It is less oxidized or strained, fine, sharp distribution in particle size, and has a large crystallite diameter. As such, when used for a conductive paste, the powder is resistant to oxidation in evaporation of volatile contents process from the conductive paste, well dispersible in the paste, and densely fills the conductive paste can downsize of electrodes, circuits or the like formed by a thick copper film. The method of the present invention can efficiently produce the flaky copper powder of the present invention. The conductive paste of the present invention is highly oxidation-resistant in evaporation of volatile contents process from the conductive paste; densely filled with the flaky copper powder; electrodes, circuits and or the like by a thick copper film can be finer; and a thick copper film can be excellent thermal expansion rate.

Problems solved by technology

However, the flaky copper powder disclosed by Patent Document 1, although fine, is produced by breaking agglomerated copper particles and then deforming the broken particles by compression in a high-energy ball mill.
As a result, it involves problems that it tends to be oxidized or strained during the compression deformation step and to have small crystallite diameter.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0082] Pure water (6 L) kept at 70° C. was added with 4 kg of copper sulfate pentahydrate, 120 g of aminoacetic acid and 50 g of sodium phosphate with stirring, and the resulting aqueous solution was further added with pure water to 8 L and continuously kept stirred for 30 minutes.

[0083] Next, the aqueous solution was added, while it was kept stirred, with 5.8 kg of a 25 wt % aqueous solution of sodium hydroxide, kept stirred for 30 minutes, and further added with 1.5 kg of glucose, and kept stirred for 30 minutes.

[0084] Then, the resulting aqueous solution was added, while it was kept stirred, with 1 kg of 100 wt % hydrated hydrazine (N2H4·H2O) slowly taking 5 minutes, and kept stirred for 1 hour to complete the reaction.

[0085] On completion of the reaction, the resulting slurry was filtered using a Buchner funnel, and the precipitate was rinsed with pure water and then rinsed with methanol, and dried to prepare the flaky copper powder.

[0086] The flaky copper powder was analyze...

example 2

[0092] Pure water (6 L) kept at 70° C. was added with 4 kg of copper sulfate pentahydrate, 120 g of aminoacetic acid and 75 g of sodium phosphate with stirring, and the resulting aqueous solution was further added with pure water to 8 L and continuously kept stirred for 30 minutes.

[0093] Next, the aqueous solution was added, while it was kept stirred, with 5.8 kg of a 25 wt % aqueous solution of sodium hydroxide, kept stirred for 30 minutes, and further added with 1.5 kg of glucose, and kept stirred for 30 minutes.

[0094] Then, the resulting aqueous solution was added, while it was kept stirred, with 1 kg of 100 wt % hydrated hydrazine (N2H4·H2O) slowly taking 30 minutes, and kept stirred for 1 hour to complete the reaction.

[0095] On completion of the reaction, the resulting slurry was filtered using a Buchner funnel, and the precipitate was rinsed with pure water and then rinsed with methanol and dried to prepare the flaky copper powder.

[0096] The flaky copper powder was analyze...

example 3

[0099] Pure water (6 L) kept at 70° C. was added with 4 kg of copper sulfate pentahydrate, 120 g of aminoacetic acid and 75 g of sodium phosphate with stirring, and the resulting aqueous solution was further added with pure water to 8 L and continuously kept stirred for 30 minutes.

[0100] Next, the aqueous solution was added, while it was kept stirred, with 5.8 kg of a 25 wt % aqueous solution of sodium hydroxide, kept stirred for 30 minutes, and further added with 1.5 kg of glucose, and stirring was continued for 30 minutes.

[0101] Then, the resulting aqueous solution was added, while it was kept stirred, with 1 kg of 100 wt % hydrated hydrazine (N2H4·H2O) slowly taking 30 minutes, and kept stirred for 1 hour to complete the reaction.

[0102] On completion of the reaction, the resulting slurry was filtered using a Buchner funnel, and the precipitate was rinsed with pure water and then with methanol. The filtration residue was immersed for one hour in a methanol solution which is obt...

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Abstract

It is an object of the present invention to provide a flaky copper powder composed of fine particles having a sharp distribution particle size, a large crystallite diameter and high oxidation resistance. The flaky copper powder of the present invention contains P and has a crystallite diameter / D1A ratio of 0.01 or more to achieve the object. The method for producing the flaky copper powder comprises four steps: a first step of preparing an aqueous solution containing a copper salt and complexing agent; a second step of adding an alkali hydroxide to the aqueous solution to prepare a first slurry containing cupric oxide; a third step of adding a first reducing agent which can reduce the cupric oxide into cuprous oxide to the first slurry to prepare a second slurry containing cuprous oxide; and a fourth step of adding a second reducing agent which can reduce the cuprous oxide into copper to the second slurry to provide a flaky copper powder, wherein phosphoric acid and its salt are added in at least one of the first to third steps and / or in the second slurry in the fourth step.

Description

TECHNICAL FIELD [0001] The present invention relates to a flaky copper powder, a method for producing the same and a conductive paste. More specifically a flaky copper powder useful as a raw material for a copper paste which is used for securing electrical continuity of electrical circuits on printed circuit substrate and external electrodes of ceramic condensers and the like, a method for producing the same and a conductive paste. BACKGROUND ART [0002] One of the convertible methods for forming electrodes or circuits in an electronic device or the like is, that printing a conductive paste in which a copper powder is dispersed as a conductive material on a substrate and then hardening by calcining or curing the paste to obtain electrodes or circuits. [0003] Recently, as the markets have required downsizing and higher density for electronic devices for multi functional electronic devices, so, a copper powder for a conductive paste is required to have distribution sharper in particle ...

Claims

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Application Information

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IPC IPC(8): B22F9/24B22F1/00B22F1/052B22F1/068B22F1/102B22F1/16H01B1/02H01B1/22H01B13/00H05K1/09
CPCB22F9/24H01B1/22H05K1/095B22F1/0551B22F1/07B22F1/052B22F1/068B22F1/102B22F1/16B22F1/00H01B1/02
Inventor SAKAUE, TAKAHIKOYOSHIMARU, KATSUHIKONAKAMURA, YOSHINOBUSHIMAMURA, HIROYUKI
Owner MITSUI MINING & SMELTING CO LTD
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