# US 7,291,200 B2 · Monodisperse spherical metal particles and manufacturing method therefor

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- Number: US 7,291,200 B2
- Document ID: US7291200B2
- Status: Granted
- Kind: B2
- Application number: 11/043,633
- Filed: 2005-01-26
- Published: 2005-06-16
- Granted: 2007-11-06
- Earliest claimed: 2001-10-26
- Assignees: Miyazaki Prefecture
- Inventors: Masataka Shimizu; Kiyoshi Torigoe; Tadao Nakashima; Izumi Akazaki
- Web page: https://patentgrep.com/patent/US7291200B2

## CPC

- B23K 35/0244: {Powders, particles or spheres; Preforms made therefrom}
- B22F 1/052: characterised by a mixture of particles of different sizes or by the particle size distribution
- B22F 9/08: by casting, e.g. through sieves or in water, by atomising or spraying (using electric discharge B22F9/14)
- B22F 2009/0808: {Mechanical dispersion of melt, e.g. by sieves}
- B23K 35/025: {Pastes, creams or slurries}
- H05K 3/3485: Application of solder paste, slurry or powder (using printing techniques to form the desired conductive pattern of the printed circuit by applying conductive material H05K3/12)
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

It is an object of the present invention to provide spherical metal particles having excellent monodispersity. The present invention relates to a method of manufacturing monodisperse spherical metal particles characterized by passing liquid metal through a porous membrane so as to disperse the resulting liquid metal particles in a continuous liquid phase.

## Claims

### Claim 1

A method of manufacturing monodisperse spherical metal particles, comprising passing liquid metal through a porous membrane and dispersing the resulting liquid metal particles directly in a continuous liquid phase.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the porous membrane is a porous glass membrane.

### Claim 3 (depends on 2)

The method of claim 2, wherein the monodisperse spherical metal particles have a mean particle diameter in the range of 0.1-160 μm.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the liquid metal is a metal having a melting point of at most 250° C. which has been melted.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the continuous liquid phase further contains a dispersant.

### Claim 6 (depends on 5)

The method according to claim 5, wherein the dispersant is a metallic soap.

### Claim 7 (depends on 1)

The method of claim 1, wherein the monodisperse spherical metal particles have a mean particle diameter (particle diameter corresponding to 50 vol % in the cumulative volume distribution) in the range of 0.1-1000 μm.

### Claim 8 (depends on 1)

The method of claim 1, wherein the monodisperse spherical metal particles have a cumulative volume distribution in which:
(a) a particle diameter corresponding to 10 vol % in the distribution is at least 60% of the particle diameter corresponding to 50 vol % in the distribution; and
(b) a particle diameter corresponding to 90 vol % in the distribution is at most 125% of the particle diameter corresponding to 50 vol % in the distribution.

### Claim 9 (depends on 8)

The method of claim 8, wherein a particle diameter corresponding to 50 vol % in the distribution is 10 μm or smaller.

### Claim 10 (depends on 1)

The method of manufacturing monodisperse spherical metal particles as claimed in claim 1 as solder balls for BGA/CSP type packages.