Conductive material and process

• US 10,999,933 B2
• Filed: 03/03/2014
• Issued: 05/04/2021
• Est. Priority Date: 09/06/2011
• Status: Active Grant

• Current Assignee: Henkel AG & Co KGaA
• Original Assignee: Henkel IP & Holding GmbH (Henkel AG & Co KGaA)
• Inventors: Wei, Bin, Huang, Xiaoyan, Xiao, Allison Yue
• Primary Examiner(s): Turocy, David P
• Assistant Examiner(s): Mayy, Mohammad
• Application Number:
  US14/195,239
• Publication Number:
  US 20140178601A1
• Time in Patent Office: 2,619 Days
• Field of Search: None
• CPC Class Codes: B41M 5/0023 Digital printing methods characterised by the inks used inks per se C09D11/00
• CPC Class Codes: C09D 11/52 Electrically conductive inks
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H05K 1/092 Dispersed materials, e.g. conductive pastes or inks
• CPC Class Codes: H05K 2203/1131 Sintering, i.e. fusing of metal particles to achieve or improve electrical conductivity
• CPC Class Codes: H05K 2203/125 Inorganic compounds, e.g. silver salt
• CPC Class Codes: H05K 3/027 the conductive material being removed by irradiation, e.g. by photons, alpha or beta particles
• CPC Class Codes: H05K 3/105 by conversion of non-conductive material on or in the support into conductive material, e.g. by using an energy beam
• CPC Class Codes: H05K 3/1283 After-treatment of the printed patterns, e.g. sintering or curing methods

Abstract

A method for making a conductive network of sintered silver comprises preparing a conductive ink comprising a silver compound and a binder; depositing the conductive ink on a substrate and applying an external energy source to the deposited conductive ink to dry the ink; and applying an external energy source to the dried ink to decompose the ink to elemental silver and to sinter the elemental silver into a conductive network.

Claims

1. A method for making a conductive network of sintered silver in an organic matrix comprising:

(a) depositing an ink consisting essentially of a silver compound, a reducing agent, an organic binder and an optional solvent,

wherein the silver compound is silver oxalate and is present in an amount of about 18% by weight, based on the total weight of the ink;

wherein the reducing agent comprises isopropanolamine in an amount of about 36% by weight, octylamine in an amount of about 9% by weight, and ethanol in an amount of about 36% by weight, each based on the total weight of the conductive ink composition;

wherein the organic binder includes polyvinylpyrrolidone and is present in the amount of about 0.1-30% by weight of the total ink and forms into the organic matrix;

on a substrate and applying an external energy source to dry the deposited ink; and

(b) applying an additional external energy source to the dried ink to decompose the silver compound to elemental silver and to sinter the elemental silver into a conductive network in the organic matrix,

wherein the additional external energy source comprises pulsed UV irradiation, and

wherein the organic matrix remains substantially intact following pulse UV irradiation.

2. The method according to claim 1, in which the silver compound is a combination of silver formate and silver oxalate.

3. The method according to claim 1 in which the reducing agent further comprises methanol, isopropanol, terpineol, t-butanol, ethylene glycol, diethylene glycol, triethylene glycol, ethylene glycol diacetate, formaldehyde, octanal, decanal, dodecanal, or dimethylformamide.

4. The method according to claim 1 in which the external energy source to dry the ink is heat at a temperature or within a temperature range from 25°

to 200°

C.

5. The method of claim 1, wherein the reducing agent further includes an oxime, guanidine, carbazone, a further alcohol, polyol, hydrazine, hydrazine, hydrazide, aldehyde, or amide.

6. The method of claim 1, wherein after applying pulsed UV irradiation, resistance drops by at least eight orders of magnitude.

7. A method for making a conductive network of sintered silver in an organic matrix comprising:

(a) depositing an ink consisting of a silver compound, a reducing agent, an organic binder, and an optional solvent,

wherein the silver compound is silver oxalate;

wherein the silver compound is about 18% by weight of the total conductive ink composition;

wherein the reducing agent comprises isopropanolamine in an amount of about 36% by weight, octylamine in an amount of about 9% by weight, and ethanol in an amount of about 36% by weight, each based on the total weight of the conductive ink composition;

wherein the organic binder includes polyvinylpyrrolidone and is present in the amount of about 0.1-30% by weight of the total ink and forms into the organic matrix on a substrate and applying an external energy source to dry the deposited ink; and

(b) applying an additional external energy source to the dried ink to decompose the silver compound to elemental silver and to sinter the elemental silver into a conductive network in the organic matrix,

wherein the additional external energy source comprises pulsed UV irradiation and

wherein the organic matrix remains substantially intact following pulse UV irradiation.

8. The method of claim 7, wherein the reducing agent further includes an oxime, guanidine, carbazone, a further alcohol, polyol, hydrazine, hydrazine, hydrazide, aldehyde, or an amide.

9. The method of claim 7, wherein after applying pulsed UV irradiation, resistance drops by at least eight orders of magnitude.