Metal powder sintering paste and method of producing the same, and method of producing conductive material

Patent metadata

Field	Value
Publication number	US-11634596-B2
Application number	US-202117158295-A
Country	US
Kind code	B2
Filing date	Jan 26, 2021
Priority date	Apr 4, 2016
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

Abstract

There is a problem that when a silver powder sintering paste that is substantially free from resin is used, an organic solvent used as a dispersion medium bleeds, which results in contamination and wire bonding defects. In order to solve the problem, provided is a metal powder sintering paste that contains, as a principal component, silver particles having an average particle diameter (a median diameter) of 0.3 μm to 5 μm and further contains an anionic surfactant but is substantially free from resin.

First claim

The invention claimed is:

1. A metal powder sintering paste,
the paste comprising, as a principal component, silver particles having a median diameter of 0.3 μm to 5 μm, and
further comprising an anionic surfactant, and
being substantially free from resin,
wherein
in the silver particles, a content of particles with a particle diameter of smaller than 0.3 μm is not more than 5% by mass,
wherein
a content of the surfactant is not more than 2% by mass with respect to the paste, and
wherein
the surfactant is a saturated carboxylic acid represented by Formula (I) below:
R 1 O(CH 2 CH(R 2 )O) n1 CH 2 COOR 3   (I)

wherein R 1 is a linear or branched alkyl group having at least 7 carbon atoms,
R 2 is any one of —H, —CH 3 , —CH 2 CH 3 , and —CH 2 CH 2 CH 3 ,
R 3 is —H or alkali metal, and
n1 is in a range of 2 to 5.

2. The metal powder sintering paste according to claim 1 , wherein
the surfactant is one in which when the temperature is increased with thermogravimetric-differential thermal analysis (TG-DTA) from room temperature to 350° C. at 2° C./min, a residue is reduced to not more than 20% by mass with respect to the initial mass.

3. The metal powder sintering paste according to claim 1 , wherein
the surfactant is liquid at 25° C.

4. The metal powder sintering paste according to claim 1 , wherein
the silver particles are in a flake form.

5. The metal powder sintering paste according to claim 1 , wherein
in the silver particles, the content of particles with a particle diameter of smaller than 0.5 μm is not more than 15% by mass.

6. The metal powder sintering paste according to claim 1 , wherein
the metal powder sintering paste further comprises an organic solvent as a dispersion medium.

7. The metal powder sintering paste according to claim 6 , wherein
the organic solvent has a boiling point in a range of 150 to 250° C.

8. The metal powder sintering paste according to claim 1 , capable of being sintered to form a conductive material having an electric resistance of not higher than 6 μΩ·cm.

9. The metal powder sintering paste according to claim 1 , wherein
a content of the silver particles is at least 70% by mass with respect to the paste.

Assignees

• Nichia Corp

Inventors

• Kunimune Teppei
• Kuramoto Masafumi

Classifications

• H10W72/071 Primary

  Connecting or disconnecting · CPC title

• C09D7/68

  Particle size between 100-1000 nm · CPC title

• B22F2301/255

  Silver or gold · CPC title

• C09J11/04

  inorganic · CPC title

• B22F9/30

  with decomposition of metal compounds, e.g. by pyrolysis · CPC title