Conductive paste comprising a silicone oil

• US 10,453,974 B2
• Filed: 02/23/2017
• Issued: 10/22/2019
• Est. Priority Date: 02/23/2016
• Status: Active Grant

• Current Assignee: BASF SE
• Original Assignee: BASF SE
• Inventors: Fiess, Markus, Pan, Han Chang, Wang, Yu Lin, Cho, Chia Chin
• Primary Examiner(s): Smoot, Stephen W
• Application Number:
  US16/078,176
• Publication Number:
  US 20190051774A1
• Time in Patent Office: 971 Days
• CPC Class Codes: C03C 2204/00 Glasses, glazes or enamels with special properties
• CPC Class Codes: C03C 2205/00 Compositions applicable for the manufacture of vitreous enamels or glazes
• CPC Class Codes: C03C 4/14 for electro-conductive glass
• CPC Class Codes: C03C 8/18 containing free metals
• CPC Class Codes: H01B 1/02 mainly consisting of metals or alloys
• CPC Class Codes: H01B 1/124 Intrinsically conductive polymers
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01B 1/24 the conductive material comprising carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H01L 21/705 of thick-film circuits or parts thereof
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

The invention relates to a conductive paste comprising from 30 to 97% by weight of electrically conductive particles, from 0 to 20% by weight of a glass frit, from 3 to 70% by weight of an organic medium and from 0.1 to 67% by weight of a silicone oil, each based on the total mass of the paste, wherein the silicone oil has a boiling point or a boiling range in the range between 180° C. and 350° C. The invention further relates to a use of the conductive paste and a process for producing electrodes on a semiconductor substrate using the paste.

Claims

1. A conductive paste comprising:

from 30 to 97% by weight of electrically conductive particles;

from 1 to 20% by weight of a glass frit;

from 3 to 70% by weight of an organic medium; and

from 0.1 to 67% by weight of a silicone oil;

wherein each % by weight is based on a total mass of the conductive paste; and

wherein the silicone oil has a boiling point or a boiling range in a range between 180°

C. and 350°

C.

2. The conductive paste according to claim 1, wherein the silicone oil comprises at least one selected from the group consisting of a linear silicone oil molecule, a branched silicone oil molecule, and a cyclic silicone oil molecule.

3. The conductive paste according to claim 2, comprising the linear silicone oil molecule, wherein the linear silicone oil molecule is at least one selected from the group consisting of decamethyltetrasiloxane, dodecamethylpentasiloxane, tetradecamethylhexasiloxane, and hexadecamethylheptasiloxane.

4. The conductive paste according to claim 2, comprising the cyclic silicone oil molecule, wherein the cyclic silicone oil molecule is at least one selected from the group consisting of decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and tetradecamethylcycloheptasiloxane.

5. The conductive paste according to claim 1, wherein the silicone oil comprises polydimethylsiloxane.

6. The conductive paste according to claim 1, wherein the electrically conductive particles comprise carbon, silver, gold, aluminum, platinum, palladium, tin, nickel, cadmium, gallium, indium, copper, zinc, iron, bismuth, cobalt, manganese, molybdenum, chromium, vanadium, titanium, tungsten, mixtures thereof, alloys thereof, or core-shell structures thereof.

7. The conductive paste according to claim 1, wherein the electrically conductive particles are coated with an organic additive.

8. A printed electrode on a semiconductor substrate, the printed electrode comprising the conductive paste according to claim 1.

9. A process for producing an electrode on a semiconductor substrate, the process comprising:

(a) screen printing the conductive paste according to claim 1 on a semiconductor substrate in a predetermined pattern to form a printed semiconductor substrate;

(b) drying the printed semiconductor substrate at a temperature in a range from 100 to 300°

C. to obtain a dried printed semiconductor substrate;

(c) heating the dried printed semiconductor substrate to a sintering temperature in a range from 650 to 900°

C. to sinter the electrically conductive particles.

10. The process according to claim 9, wherein the drying (b) is carried out for a duration in a range from 10 to 50 sec.

11. The process according to claim 9, wherein the heating (c) comprises:

heating the dried printed semiconductor substrate from room temperature to the sintering temperature within 5 to 50 sec;

holding the sintering temperature for 1 to 5 sec; and

cooling the dried printed semiconductor substrate down to room temperature within 3 to 60 sec.

12. The process according to claim 9, wherein the semiconductor substrate is a semiconductor substrate for a solar cell.