Aluminum-tin paste and its use in manufacturing solderable electrical conductors

Patent metadata

Field	Value
Publication number	US-9966479-B2
Application number	US-201514715113-A
Country	US
Kind code	B2
Filing date	May 18, 2015
Priority date	Jun 12, 2014
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

The present invention is directed to a paste composition comprising Al and Sn dispersed in an organic medium and to paste compositions that provide a solderable electrode. The present invention is further directed to an electrode formed from the paste composition and a semiconductor device and, in particular, a solar cell comprising such an electrode. The paste compositions that provide a solderable electrode are particularly useful for forming a solar cell back side solderable electrode.

First claim

What is claimed is:

1. A paste composition consisting of:
(a) 10-70 wt % aluminum powder having aluminum particles of particle size in the range of 0.5-10 μm;
(b) 5-85 wt % tin powder having tin particles of particle size in the range of 1-200 μm; and
(c) organic medium with 0.1-5 wt % polymer binder;

wherein said aluminum powder and said tin powder are dispersed in the organic medium and wherein the wt % are based on the total weight of said paste composition.

2. The paste composition of claim 1 , said paste composition consisting of:
(a) 15-50 wt % aluminum powder having aluminum particles of particle size in the range of 0.5-10 μm;
(b) 35-80 wt % tin powder having tin particles of particle size in the range of 10-200 μm; and
(c) organic medium with 0.1-5 wt % polymer binder;

wherein said aluminum powder and said tin powder are dispersed in said organic medium and wherein the wt % are based on the total weight of said paste composition.

3. The paste composition of claim 2 , said tin powder having tin particles of particle size in the range of 10-150 μm.

4. The paste composition of claim 1 , said paste composition consisting of:
(a) 10-25 wt % aluminum powder having aluminum particles of particle size in the range of 0.5-10μm;
(b) 65-85 wt % tin powder having tin particles of particle size in the range of 1-10 μm; and
(c) organic medium with 0.1-5 wt % polymer binder;

wherein said aluminum powder and said tin powder are dispersed in said organic medium and wherein the wt % are based on the total weight of said paste composition.

5. The paste composition of claim 4 , said tin powder having tin particles of particle size in the range of 3-10 μm.

6. A solar cell comprising:
(a) a non-solderable aluminum back side electrode containing gaps between areas of the non-solderable aluminum back side electrode; and
(b) a solderable aluminum-tin back side electrode obtained by firing a solderable aluminum-tin back side paste deposited as tabbing bus bars in the gaps between areas of the non-solderable aluminum back side electrode, said solderable aluminum-tin back side paste consisting of:
(1) 10-70 wt % aluminum powder having aluminum particles of particle size in the range of 0.5-10 μm;
(2) 5-85 wt % tin powder having tin particles of particle size in the range of 1-200 μm; and
(3) organic medium with 0.1-5 wt % polymer binder;
wherein the aluminum powder and the tin powder are dispersed in the organic medium and wherein the wt % are based on the total weight of the paste composition.

7. The solar cell of claim 6 , said tin powder having tin particles of particle size in the range of 10-150 μm.

8. A solar cell containing a front surface and a back surface, said solar cell comprising:
a solderable aluminum-tin back side electrode obtained by firing a solderable aluminum-tin back side paste covering the entire back side surface of said solar cell, said solderable aluminum-tin back side paste consisting of:
(1) 10-70 wt % aluminum powder having aluminum particles of particle size in the range of 0.5-10 μm;
(2) 5-85 wt % tin powder having tin particles of particle size in the range of 1-200 μm; and
(3) organic medium with 0.1-5 wt % polymer binder;

wherein the aluminum powder and the tin powder are dispersed in the organic medium and wherein the wt % are based on the total weight of the paste composition.

9. A solar cell containing a front surface and a back surface, said solar cell comprising:
(a) non-solderable aluminum back side electrode covering the entire back side surface; and
(b) a solderable aluminum-tin back side electrode obtained by firing a solderable aluminum-tin back side paste deposited on portions of the non-solderable aluminum back side electrode, said solderable aluminum-tin back side paste consisting of:
(1) 10-25 wt % aluminum powder having aluminum particles of particle size in the range of 0.5-10 μm;
(2) 65-85 wt % tin powder having tin particles of particle size in the range of 1-10 μm; and
(3) organic medium with 0.1-5 wt % polymer binder; wherein the aluminum powder and the tin powder are dispersed in the organic medium and wherein the wt % are based on the total weight of the paste composition.

10. The solar cell of claim 9 , said tin powder having tin particles of particle size in the range of 3-10 μm.

Assignees

• Du Pont

Inventors

• Rogojina Elena V
• Wang Gonghou
• Tai Elizabeth
• Kelman Maxim

Classifications

• C22C13/00

  Alloys based on tin · CPC title

• C22C21/003

  containing at least 2.6% of one or more of the elements: tin, lead, antimony, bismuth, cadmium, and titanium · CPC title

• B23K35/288 Primary

  with Sn or Zn · CPC title

• B23K35/025

  Pastes, creams or slurries · CPC title

• H01B1/023 Primary

  Alloys based on aluminium · CPC title