Composite nanometal paste containing copper filler and joining method

Patent metadata

Field	Value
Publication number	US-9796052-B2
Application number	US-201214389668-A
Country	US
Kind code	B2
Filing date	Mar 30, 2012
Priority date	Mar 30, 2012
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

The present invention addresses the problem of providing a composite nanometal paste which is relatively low in price and is excellent in terms of bonding characteristics, thermal conductivity, and electrical property.
The present invention is a copper-filler-containing composite nanometal paste that contains composite nanometal particles each comprising a metal core and an organic coating layer formed thereon. The metal paste contains a copper filler and contains, as binders, first composite nanometal particles and second composite nanometal particles which differ from the first composite nanometal particles in the thermal decomposition temperature of the organic coating layer, wherein the mass proportion W 1 of the organic coating layer in the first composite nanometal particles is in the range of 2-13 mass %, the mass proportion W 2 of the organic coating layer in the second composite nanometal particles is in the range of 5-25 mass %, and these particles satisfy the relationships W 1.

First claim

The invention claimed is:

1. A copper-filler-containing composite nanometal paste comprising composite nanometal particles in which each particle has an organic coating layer being an organic matter formed around a metal core, and a copper filler which has no organic coating layer,
wherein said composite nanometal particles comprise at least a first composite nanometal particle with a first organic coating layer thereon and a second composite nanometal particle with a second organic coating layer thereon in which the first and second organic coating layers have different compositions so that pyrolysis temperatures of the first and second organic coating layers differ from each other, and
wherein, when a mass percent concentration of said organic coating layers in said composite nanometical particles is defined by a term of mass ratio, a mass ratio W 1 of said first organic coating layer in said first composite nanometal particle exists within a range of 2 to 13 mass %, and a mass ratio W 2 of said second organic coating layer in said second composite nanometal particle exists within a range of 5 to 25 mass %, and
when T 1 is a pyrolysis temperature of said first organic coating layer and T 2 is a pyrolysis temperature of said second organic coating layer, relationships of T 1 <T 2 and W 1 <W 2 are satisfied for said first and second composite nanometal particles.

2. The copper-filler-containing composite nanometal paste according to claim 1 , wherein a relationship of N 1 <N 2 is satisfied where N 1 is a carbon number of said organic matter included in said first composite nanometal particle and N 2 is a carbon number of said organic matter included in said second composite nanometal particle.

3. The copper-filler-containing composite nanometal paste according to claim 2 , wherein said carbon number N 1 is selected from a range of 1 to 6, and said carbon number N 2 is selected from a range of 7 to 12.

4. The copper-filler-containing composite nanometal paste according to any one of claims 1 to 3 , wherein a metallic element forming said metal core is selected from one or more kinds among Ag, Au, Pt, Ru, Zn, Sn and Ni.

5. The copper-filler-containing composite nanometal paste according to any one of claims 1 to 3 , wherein said copper filler is contained in a range of 10 mass % to 90 mass % of total mass of said copper-filler-containing composite nanometal paste.

6. The copper-filler-containing composite nanometal paste according to any one of claims 1 to 3 , wherein said organic matter is selected from one or more kinds among an alcohol molecule, a cut residue of an alcohol molecule and an alcohol derivative derived from an alcohol molecule.

7. The copper-filler-containing composite nanometal paste according to any one of claims 1 to 3 , wherein an addition agent comprising a viscosity grant agent and/or a viscosity adjustment solvent is added, and an addition amount of said addition agent is determined by a ratio of a total amount of organic matter contained in said composite nanometal particles and a total amount of all metal ingredients contained in said copper-filler-containing composite nanometal paste.

8. The copper-filler-containing composite nanometal paste according to claim 2 or 3 , wherein a third composite nanometal particle in which a third organic coating layer comprising an organic matter of carbon number N 3 is formed around said metal core is additionally contained, a mass ratio W 3 of said third organic coating layer in said third composite nanometal particle is not more than 0.2 mass %; said carbon number N 3 satisfies a relationship of N 3 <N 2 , and a pyrolysis temperature T 3 of said third organic coating layer satisfies a relationship of T 3 <T 2 because of a difference of composition.

9. A joining method comprising the steps of forming a paste layer by applying the copper-filler-containing composite nanometal paste according to any one of claims 1 to 3 between joined members, and sintering said paste layer by heating or heating with pressurization to join said joined members.

10. The joining method according to claim 9 , wherein a sinter layer formed by sintering said paste layer absorbs a deformation caused due to difference of thermal expansion coefficients in said joined members.

11. The joining method according to claim 9 , wherein said joined members comprise first copper specimen and second copper specimen, and a shear strength with which said first copper specimen and said second copper specimen are joined is not less than 20 MPa, when a joining area of said first copper specimen is the area of a circle with a diameter of 5 mm, a joining area of said second copper specimen is larger than the area of a circle with a diameter of 5 mm, a heating temperature of said heating is not lower than 250° C. and said pressurization is not less than 5 MPa.

Assignees

• Komatsu Teruo
• Matsubayashi Ryo
• Applied Nanoparticle Laboratory Corp
• Shindengen Electric Mfg

Inventors

• Komatsu Teruo
• Matsubayashi Ryo

Classifications

• B22F1/054

  Nanosized particles · CPC title

• B22F1/102

  Metallic powder coated with organic material · CPC title

• H05K2201/0257

  Nanoparticles · CPC title

• B23K35/302

  Cu as the principal constituent · CPC title

• H05K2201/0224

  Conductive particles having an insulating coating · CPC title