# US 10,478,924 B2 · Metal particle and electroconductive paste formed therefrom

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- Number: US 10,478,924 B2
- Document ID: US10478924B2
- Status: Granted
- Kind: B2
- Application number: 16/000,202
- Filed: 2018-06-05
- Published: 2018-11-01
- Granted: 2019-11-19
- Earliest claimed: 2016-03-29
- Assignees: Napra Co., Ltd.
- Applicants: Napra Co., Ltd.
- Inventors: Shigenobu Sekine
- Web page: https://patentgrep.com/patent/US10478924B2

## CPC

- B23K 35/025: {Pastes, creams or slurries}
- B22F 1/065: Spherical particles
- B22F 1/17: Metallic particles coated with metal
- B23K 35/26: with the principal constituent melting at less than 400°C
- B23K 35/262: {Sn as the principal constituent}
- B23K 35/302: {Cu as the principal constituent}
- C22C 9/02: with tin as the next major constituent
- C22C 13/00: Alloys based on tin
- H01B 1/02: mainly consisting of metals or alloys
- H01B 1/026: {Alloys based on copper}
- H01B 1/04: mainly consisting of carbon-silicon compounds, carbon or silicon
- H01B 1/22: the conductive material comprising metals or alloys
- H10W 72/20: Bump connectors, e.g. solder bumps or copper pillars; Dummy bumps; Thermal bumps
- B22F 2301/30: Low melting point metals, i.e. Zn, Pb, Sn, Cd, In, Ga
- B22F 2301/40: Intermetallics other than rare earth-Co or -Ni or -Fe intermetallic alloys
- B22F 2303/15: Intermetallic
- B22F 2303/30: Coating alloy
- B22F 2304/10: Micron size particles, i.e. above 1 micrometer up to 500 micrometer
- H10W 72/222: {Multilayered bumps, e.g. a coating on top and side surfaces of a bump core}
- H10W 72/225: {Bumps having a filler embedded in a matrix}
- H10W 72/252: {comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu}
- 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
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

An electro-conductive paste includes a metal particle and a vehicle in which the metal particle is dispersed. The metal particle has a particle size in a range from 1 μm to 20 μm and consists of an outer shell and a core part. The core part contains Sn or a Sn alloy. The outer shell contains an intermetallic compound of Sn and Cu and covers 50% or more of a total surface area of the core part.

## Claims

### Claim 1

An electro-conductive paste comprising a metal particle and a vehicle, wherein:
the metal particle consists of a core part and an outer shell, the core part containing a metal or an alloy, the outer shell containing an intermetallic compound and covering the core part;
50% or more of a total surface area of the core part is covered with the outer shell;
a particle size of the metal particle is from 1 μm to 20 μm;
the core part containing Sn or a Sn alloy;
the outer shell containing an intermetallic compound of Sn and Cu; and
the metal particle is dispersed in the vehicle.