Silver paste

Patent metadata

Field	Value
Publication number	US-11535767-B2
Application number	US-201917417895-A
Country	US
Kind code	B2
Filing date	Nov 28, 2019
Priority date	Dec 26, 2018
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

The present invention provides a silver paste containing at least a silver powder, a binder resin, and an organic solvent, wherein the silver powder contains a first silver powder having a D50 of 3.50 to 7.50 μm and a second silver powder having a D50 of 0.80 to 2.00 μm, where D50 represents a 50% value of a volume-based cumulative fraction obtained by laser diffraction particle size distribution measurement; a copper content of the whole silver powder is 10 to 5000 ppm by mass; a copper content of the second silver powder is 80 ppm by mass or more; and the first silver powder contains substantially no copper. The present invention provides a silver paste containing a powder in a high concentration and excellent in printability, and provides a silver conductor film that has a high filling factor, a high film density, high electrical conductivity, and excellent migration resistance.

First claim

The invention claimed is:

1. A silver paste comprising at least a silver powder, a binder resin, and an organic solvent,
wherein the silver powder satisfies all of the following conditions [1] to [4]:
[1] the silver powder contains a first silver powder (a) having a D50 of 3.50 to 7.50 μm and a second silver powder (b) having a D50 of 0.80 to 2.70 μm, where D50 represents a 50% value of a volume-based cumulative fraction obtained by laser diffraction particle size distribution measurement;
[2] a copper content of the silver powder is 10 to 5000 ppm by mass;
[3] a copper content of the second silver powder (b) is 80 ppm by mass or more; and
[4] the first silver powder (a) contains substantially no copper.

2. The silver paste according to claim 1 , wherein the second silver powder (a) has a D10 of 0.70 μm or more, where D10 represents a 10% value of a volume-based cumulative fraction obtained by laser diffraction particle size distribution measurement.

3. The silver paste according to claim 1 or 2 , wherein a copper content of the first silver powder (a) is less than 50 ppm by mass.

4. The silver paste according to claim 1 , wherein the first silver powder (a) has a D50 of 3.70 to 7.50 μm.

5. The silver paste according to claim 4 , wherein the first silver powder (a) has a D50 of 4.00 to 6.00 μm.

6. The silver paste according to claim 1 , wherein the second silver powder (b) has a D50 of 0.80 to 2.00 μm.

7. The silver paste according to claim 1 , wherein the silver powder has a D10 of 1.00 to 3.00 μm, and a D50 of 3.00 to 7.00 μm.

8. The silver paste according to claim 7 , wherein the silver powder has a D10 of 1.20 to 2.00 μm.

9. The silver paste according to claim 7 or 8 , wherein the silver powder has a D50 of 3.90 to 5.00 μm.

10. The silver paste according to claim 1 , wherein a copper content of the silver powder is 30 to 500 ppm by mass.

11. The silver paste according to claim 1 , further satisfying the following condition [5]:
[5] a content C AG of the silver powder based on the silver paste is 80.00 to 97.00% by mass.

12. The silver paste according to claim 11 , wherein the content C AG of the silver powder based on the silver paste is 92.00 to 96.00% by mass.

13. The silver paste according to claim 1 , wherein the silver paste has a dry film density of 7.50 g/cm 3 or more.

14. The silver paste according to claim 1 , wherein a value C BND /S BET is 2.00 to 3.40, where S BET (m 2 /g) represents a specific surface area of the silver powder, and C BND (% by mass) represents a content percentage of the binder resin based on the silver powder.

15. The silver paste according to claim 1 , wherein a specific surface area S BET of the silver powder is 0.10 to 0.30 m 2 /g.

16. The silver paste according to claim 1 , to be used for forming a conductor film by a heat treatment at 700° C. or less.

17. The silver paste according to claim 1 , wherein a content percentage of the first silver powder (a) ((the first silver powder (a)/(the first silver powder (a)+the second silver powder (b)))×100) is 40 to 95% by mass in the silver powder.

18. The silver paste according to claim 17 , wherein the content percentage of the first silver powder (a) ((the first silver powder (a)/(the first silver powder (a)+the second silver powder (b)))×100) is 60 to 90% by mass in the silver powder.

Assignees

• Shoei Chemical Ind Co

Inventors

• Nishimura Kousuke
• Shindo Naoto
• Mashima Hiroshi
• Akimoto Yuji

Classifications

• B22F1/10 Primary

  Metallic powder containing lubricating or binding agents; Metallic powder containing organic material · CPC title

• B22F2301/255

  Silver or gold · CPC title

• H01B1/22 Primary

  the conductive material comprising metals or alloys · CPC title

• C09D11/037

  characterised by the pigment · CPC title

• B22F1/052

  characterised by a mixture of particles of different sizes or by the particle size distribution · CPC title