Thick film conductive composition and use thereof
View Patent ↗The invention relates to a thick film conductive composition comprising metal particles wherein the specific surface area of the silver particles measured by BET according to ISO 9277 is equal to or more than 1.8 m 2 /g; manganese oxide; glass particles; and an organic vehicle.
1. A thick film conductive composition comprising:
(a) metal particles, wherein the specific surface area of the metal particles measured by BET according to ISO 9277 is equal to or greater than 1.8 m 2 /g;
(b) manganese oxide;
(c) glass particles; and
(d) an organic vehicle.
2. The thick film composition of claim 1 , wherein the manganese oxide is 0.2 to 5 wt.-% based on the total composition.
3. The thick film composition of claim 1 , wherein the manganese oxide is Mn(II)O.
4. The thick film composition of claim 2 , wherein the metal particles are 10-75 wt.-% based on the total composition, the glass particles are 0.5-10 wt.-% based on the total composition, and the organic vehicle is 25-70 wt.-% based on the total composition.
5. The thick film composition of claim 1 , wherein the metal particles comprise silver.
6. A method of forming soldering pads, comprising the steps of:
(a) applying a dielectric layer to a semiconductor substrate; and
(b) applying a thick film conductive composition according to claim 1 on the dielectric layer to form soldering pads.
7. The method according to claim 6 , wherein the manganese oxide is 0.2 to 5 wt.-% based on the total composition.
8. The method according to claim 6 , wherein the manganese oxide is Mn(II)O.
9. The method according to claim 7 , wherein the metal particles are 10-75 wt.-% based on the total composition, the glass particles are 0.5-10 wt.-% based on the total composition, and the organic vehicle is 25-70 wt.-% based on the total composition.
10. The method according to claim 6 , wherein the metal particles comprise silver.
11. The method according to claim 6 , comprising the step of forming the soldering pads on the backside of the semiconductor substrate.
12. A method of forming soldering bus bars, comprising the steps of:
(a) applying a dielectric layer to a semiconductor substrate; and
(b) applying a thick film conductive composition according to claim 1 on the dielectric layer to form bus bars.
13. The method according to claim 12 , wherein the manganese oxide is 0.2 to 5 wt.-% based on the total composition.
14. The method according to claim 12 , wherein the manganese oxide is Mn(II)O.
15. The method according to claim 13 , wherein the metal particles are 10-75 wt.-% based on the total composition, the glass particles are 0.5-10 wt.-% based on the total composition, and the organic vehicle is 25-70 wt.-% based on the total composition.
16. The method according to claim 12 , wherein the metal particles comprise silver.
17. The method according to claim 12 , comprising the step of forming the soldering bus bars on the front side of the semiconductor substrate.
18. A method of making a solar cell, comprising the steps of:
(a) providing a semiconductor substrate comprising at least one dielectric layer deposited onto a surface of the semiconductor substrate;
(b) applying a thick-film composition according to claim 1 onto at least a portion of the dielectric layer to form a layered structure;
(c) firing the layered structure to form a soldering element in contact with the dielectric layer of the semiconductor substrate.
19. The method according to claim 18 , comprising the steps of:
(a) first applying the dielectric layer to a front side of the semiconductor substrate; and
(b) next applying the thick-film composition to the front side of the semiconductor substrate to form bus bars.
20. The method according to claim 18 , comprising the steps of:
(a) first applying the dielectric layer to a backside of the semiconductor substrate; and
(b) next applying the thick-film composition to the backside of the semiconductor substrate to form soldering pads.
21. The thick film composition of claim 1 , wherein the particle size of the manganese oxide is equal to or less than 200 nm.
22. The thick film composition of claim 1 , wherein the metal particles are 10-70 wt.-% based on the total composition.
23. The thick film composition of claim 1 , wherein the specific surface area of the metal particles measured by BET according to ISO 9277 is 2.0 to 3.0 m 2 /g.