Highly crystalline silver powder and method for producing the same

a silver powder and high-crystalline technology, applied in the field of high-crystalline silver powder, to achieve excellent thermal shrinkage resistance, high dispersibility, and excellent filling properties of conductive paste with silver powder in the process

Inactive Publication Date: 2009-01-22
MITSUI MINING & SMELTING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0027]Since the highly crystalline silver powder according to the present invention is of fine particles, has high dispersibility, and whose particle size distribution is not excessively sharp and relatively broad, and crystallites are large. And when it is used as a material for a conductive paste, the dispersibility of the silver powder to the conductive paste and the filling property of the conductive paste with the silver powder in can be excellent; an electrode, circuit and the like can be finer; the thick silver film obtained from the conductive paste can be excellent in thermal shrinkage resistance; and the resistivity thereof can be lowered. The method for producing the highly crystalline silver powder according to the present invention can efficiently produce the above-described highly crystalline silver powder according to the present invention.

Problems solved by technology

However, when the conductive paste is printed on the ceramic substrate, since the thermal shrinkage of the ceramic substrate is generally different from the thermal shrinkage of the thick silver film formed from the conductive paste, there is possibility wherein the thick silver film is separated from the ceramic substrate, or the substrate itself is deformed.
As a cause of the thermal shrinkage of the above-described thick silver film in such baking process, it is considered that the silver powder in the conductive paste causes sintering during baking.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0054]10 g of PVP (K-value: 30), 50 g of silver nitrate and 24.6 g of concentrated nitric acid (concentration: 61 wt %) were added into 500 g of pure water at room temperature, and dissolved by stirring to prepare a first aqueous solution (first aqueous solution A). In addition, 35.8 g of ascorbic acid was added into 500 g of pure water at room temperature, and dissolved by stirring to prepare a second aqueous solution (second aqueous solution A). The compositions of the first aqueous solution and the second aqueous solution are shown in Table 1 and Table 2.

[0055]Next, the second aqueous solution A was added to the stirring first aqueous solution A at once, after that, stirring was continued for 5 minutes to grow particles in the blended solution. Thereafter, stirring was stopped to settle the particles in the blended solution. After settling the particles, the supernatant of the blended solution was disposed, and the rest of blended solution was filtered using a Nutsche. Then the f...

example 2

[0058]20 g of PVP (K-value: 30), 50 g of silver nitrate and 24.6 g of concentrated nitric acid (concentration: 61%) were added into 500 g of pure water at room temperature, and dissolved by stirring to prepare a first aqueous solution (first aqueous solution B). In addition, 35.8 g of ascorbic acid was added into 500 g of pure water at room temperature, and dissolved by stirring to prepare a second aqueous solution (second aqueous solution A). The compositions of the first aqueous solution and the second aqueous solution are shown in Table 1 and Table 2.

[0059]Next, the second aqueous solution A was added to the first aqueous solution B in at once, after that, stirring was continued for 5 minutes to grow particles in the blended solution. Thereafter, stirring was stopped to settle the particles in the blended solution. After settling the particles, the supernatant of the blended solution was filtered using a Nutsche. Then, the filtered product was rinsed with pure water and dried, an...

example 3

[0064]1.0 g of gelatin (manufactured by Nitta Gelatin Inc.), 50 g of silver nitrate and 24.6 g of concentrated nitric acid (concentration: 61%) were added into 250 g of pure water at room temperature, and then, heated up to 50° C. and dissolved by stirring to prepare a first aqueous solution (first aqueous solution D). In addition, 26.4 g of ascorbic acid was added into 250 g of pure water at room temperature, and dissolved by stirring to prepare a second aqueous solution (second aqueous solution C). The compositions of the first aqueous solution D and the second aqueous solution C are shown in Table 1 and Table 2.

[0065]Next, the second aqueous solution C at room temperature was gradually added to the stirring first aqueous solution D at 50° C. in 30 minutes, after that, stirring was continued for 5 minutes to grow particles in the blended solution. Thereafter, stirring was stopped to settle the particles in the blended solution. After settling the particles, the supernatant of the ...

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Abstract

An object of the present invention is to provide highly crystalline silver powder which is characterized in fine particles, showing high dispersibility, it's particle size distribution is not excessively sharp but relatively broad and crystallites are large; and a method for producing the same. In order to achieve the object, a method for producing highly crystalline silver powder is characterized in that mixing a first aqueous solution and a second aqueous solution, wherein the first aqueous solution contains silver nitrate, a dispersing agent and nitric acid, and the second solution contains ascorbic acid. For dispersing agent, polyvinylpyrrolidone or gelatin is preferred. Highly crystalline silver powder produced by the above-described method is preferred to be a crystallite diameter of 300 Å or more, an average particle diameter D50 in the range from 0.5 μm to 10 μm, and a thermal shrinkage rate for the length direction after heating at 700° C. in the range from −3% to 3%. For ratio D90 / D10 of the silver powder is preferred to be in the range from 2.1 to 5.0.

Description

TECHNICAL FIELD[0001]The present invention relates to highly crystalline silver powder and a method for producing the same, and more specifically, to highly crystalline silver powder preferable for production of a conductive paste that can significantly reduce the size of the electrode or circuit of, for example, a chip devices, plasma display panel and the like with high density, high accuracy and high reliability. In particular it can enable to form a minute wiring or a thin and flat coating film with high density, high accuracy and high reliability. It is because the silver powder is composed of fine particles, has high dispersibility, particle size distribution is not excessively sharp but is relatively broad, and crystallites are large. So when it is used as the material for the conductive paste, the dispersibility of the silver powder and the filling properties of the paste are excellent, and then the size of the electrode or circuit formed from the thick silver film can be re...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C5/06B22F9/24B22F1/00
CPCB22F1/0044Y10T428/12014B22F9/24B22F1/07B22F1/00
Inventor FUJIMOTO, TAKUSASAKI, TAKUYAYOSHIMARU, KATSUHIKOSHIMAMURA, HIROYUKI
Owner MITSUI MINING & SMELTING CO LTD
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