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US 2026/0307143 A1Published application
Copper paste
AssigneeMaterial Concept, Inc.
InventorJunichi KOIKE
Life of this patent
Estimating the term…
Abstract
A copper paste according to the present invention contains copper powder and an alcohol solvent, where the alcohol solvent contains a first alcohol composed of at least one type of alcohol selected from the group comprising monohydric alcohols and dihydric alcohols, which has a viscosity of 3 mPa·s or more and 70 mPa·s or less at 25° C.; and a second alcohol composed of at least one type of dihydric alcohols and trihydric alcohols, which has a viscosity of 300 mPa·s or more and 1000 mPa·s or less at 25° C., and the viscosity of η10 at a shear rate of 10 s−1 at 25° C. is 1 Pa·s or more and 50 Pa·s or less, and the square root of √σ0 of the Casson yield stress of σ0 is 10 Pa1/2 or less.
Claims16
1:
- A copper paste comprising copper powder and an alcohol solvent, wherein
- the alcohol solvent contains:
- a first alcohol composed of at least one type of alcohol selected from the group comprising monohydric alcohols and dihydric alcohols, which has a viscosity of 3 mPa·s or more and 70 mPa·s or less at 25° C.;
- and
- a second alcohol composed of at least one type of dihydric alcohols and trihydric alcohols, which has a viscosity of 300 mPa·s or more and 1000 mPa·s or less at 25° C., and wherein
- the viscosity of η10 at a shear rate of 10 s−1 at 25° C. is 1 Pa·s or more and 50 Pa·s or less, and the square root of √σ0 of the Casson yield stress of σ0 is 10 Pa1/2 or less.
3 more elements
2:
- The copper paste according to claim 1, wherein the square root of √η∞ of the Casson viscosity of η∞ is 1 Pa·s1/2 or less.
3:
- The copper paste according to claim 1, wherein the copper powder further comprises:
- first copper particles which have an average particle diameter of 50 nm or more and 900 nm or less,
- second copper particles which have an average particle diameter of 150 nm or more and 1 μm or less, which are at least 100 nm larger than the average particle diameter of the first copper particles, and
- third copper particles that are in a plate-shape, a scaly shape, a flat-shape, or a flaky shape and have an average particle diameter of 1.5 μm or more and 20 μm or less.
1 more element
4:
- The copper paste according to claim 3, wherein
- the copper powder contains, relative to 100 mass % of the copper powder,
- 1 mass % or more and 30 mass % or less of the second copper particles, and
- 5 mass % or more and 60 mass % or less of the third copper particles.
1 more element
5:
- The copper paste according to claim 1, wherein
- the total amount of the first alcohol and the second alcohol is 5 mass % or more and 50 mass % or less, relative to the total mass of the copper powder, the first alcohol, and the second alcohol, which is 100 mass %.
6:
- The copper paste according to claim 1, wherein
- the paste contains no resin or contains resin in an amount of more than 0 mass % and 10 mass % or less, relative to 100 mass % of the copper powder.
7:
- The copper paste according to claim 1, which does not contain a silane coupling agent that has an epoxy group and a silane coupling agent that has an amino group, or contains the silane coupling agent that has the epoxy group and the silane coupling agent that has the amino group in an amount of more than 0 mass % and 0.05 mass % or less, relative to 100 mass % of the copper powder.
8:
- The copper paste according to claim 1, wherein
- the first alcohol contains one or more alcohols selected from the group comprising 1-hexanol, 1-heptanol, 2-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, benzyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 2,3-butanediol.
9:
- The copper paste according to claim 3, wherein
- at least one of the first copper particles and the second copper particles has polysaccharides coated on at least a part of their surface.
10:
- The copper paste according to claim 3, wherein
- at least one of the first copper particles and the second copper particles has one or more acids selected from the group comprising octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, and tetradecanoic acid on at least a part of its surface.
11:
- The copper paste according to claim 2, wherein the copper powder further comprises:
- first copper particles which have an average particle diameter of 50 nm or more and 900 nm or less,
- second copper particles which have an average particle diameter of 150 nm or more and 1 μm or less, which are at least 100 nm larger than the average particle diameter of the first copper particles, and
- third copper particles that are in a plate-shape, a scaly shape, a flat-shape, or a flaky shape and have an average particle diameter of 1.5 μm or more and 20 μm or less.
1 more element
12:
- The copper paste according to claim 11, wherein
- the copper powder contains, relative to 100 mass % of the copper powder,
- 1 mass % or more and 30 mass % or less of the second copper particles, and
- 5 mass % or more and 60 mass % or less of the third copper particles.
1 more element
13:
- The copper paste according to claim 2, wherein
- the total amount of the first alcohol and the second alcohol is 5 mass % or more and 50 mass % or less, relative to the total mass of the copper powder, the first alcohol, and the second alcohol, which is 100 mass %.
14:
- The copper paste according to claim 2, wherein
- the paste contains no resin or contains resin in an amount of more than 0 mass % and 10 mass % or less, relative to 100 mass % of the copper powder.
15:
- The copper paste according to claim 2, which does not contain a silane coupling agent that has an epoxy group and a silane coupling agent that has an amino group, or contains the silane coupling agent that has the epoxy group and the silane coupling agent that has the amino group in an amount of more than 0 mass % and 0.05 mass % or less, relative to 100 mass % of the copper powder.
16:
- The copper paste according to claim 2, wherein
- the first alcohol contains one or more alcohols selected from the group comprising 1-hexanol, 1-heptanol, 2-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, benzyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 2,3-butanediol.