Electrical and thermal conductive paste composition and method of reducing percolation threshold and enhancing percolating conductivity using the same

• US 20160358687A1
• Filed: 03/10/2015
• Published: 12/08/2016
• Est. Priority Date: 03/11/2014
• Status: Active Grant

• Current Assignee: Hong Kong University of Science and Technology
• Original Assignee: Hong Kong University of Science and Technology
• Inventors: YUEN, Matthew Ming-Fai, ZHANG, Xinfeng
• Granted Patent: US 9,870,843 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C08J 2333/12 Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C08J 2363/02 Polyglycidyl ethers of bis-phenols
• CPC Class Codes: C08J 2383/04 Polysiloxanes
• CPC Class Codes: C08J 3/205 in the presence of a continuous liquid phase
• CPC Class Codes: C08J 3/212 and solid additives
• CPC Class Codes: C08K 9/00 Use of pretreated ingredients
• CPC Class Codes: C09D 5/24 Electrically-conducting paints conductive materials H01B1/00
• CPC Class Codes: C09D 5/26 Thermosensitive paints
• CPC Class Codes: C09K 5/14 Solid materials, e.g. powdery or granular
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys

Abstract

An electrical and thermal conductive paste composition includes a wetting agent that is arranged as a conduction promoter. Further, a method produces an electrical and thermal conductive paste composition by using a wetting agent as a conduction promoter or a conductivity promoter. The electrical and thermal conductivity of a conductive particle-filled polymer composite is enhanced by using the wetting agent. Capillary forces exerted by the wetting agent cause a particle-filled polymeric suspension to percolate at a decreased volume fraction into a highly conductive network and enhance the conductivity of the composite. Through a jamming gelation technique, the percolation threshold in the particle filled polymer composite is lowered to as low as 3 volume percent. As a result, the electrical and thermal conductivity of the composite is maintained at a significantly lower filler volume fraction with a reduction of particle filler content of up to 50 weight percent.

Claims

1. An electrical and thermal conductive composite comprising:

a base material configured to form a matrix and mixed with conductive particulate fillers, thereby forming a polymeric suspension;

a conduction promoter configured to saturate a filler surface, wherein the conduction promoter is an immiscible wetting agent having an ultra-low particle filler volume fraction;

capillary bridges configured between the conductive particulate fillers; and

a conductive network including a percolated polymeric suspension and the capillary bridges.

2. The electrical and thermal conductive composite of claim 1, further comprising auxiliary components mixed with the base material and the conductive particulate fillers.

3. The electrical and thermal conductive composite of claim 2,

wherein the auxiliary components are selected from any type of liquid or powder and are configured as a functional additive to the electrical and thermal conductive composite, and

wherein the functional additive is selected from at least one of an organic solvent configured as a diluent, a prepolymer compound configured as a thickening agent, an inorganic nanoparticle configured as a thixotropic agent, a curing agent, and a catalyst.

4. The electrical and thermal conductive composite of claim 1, wherein the base material is selected from at least one of polymers, biomacromolecular materials, organic-inorganic sol-gels, metals, metal oxide, ceramics and/or precursors or derivatives of polymers, biomacromolecular materials, organic-inorganic sol-gels, metals, metal oxide, and ceramics.

5. The electrical and thermal conductive composite of claim 4,

wherein the base material further comprises polymer materials, and

wherein the polymer materials are selected from at least one of polymer solutions or polymer suspensions, thermo-plastics, thermo-setting resins, rubbers, elastomers, polymer gels, hydrogels, organogels, or other types of macromolecular based materials or derivatives of polymer solutions or polymer suspensions, thermo-plastics, thermo-setting resins, rubbers, elastomers, polymer gels, hydrogels, organogels, and types of macromolecular based materials.

6. The electrical and thermal conductive composite of claim 1,

wherein the conductive particulate fillers are selected from at least one of metal, non-metal, metal oxide, ceramic powders or a derivative form of metal, non-metal, metal oxide, and ceramic powders, and

wherein each conductive particulate filler particle size is tens of a nanometer to a few millimeters.

7. The electrical and thermal conductive composite of claim 1, wherein the conduction promoter is selected from at least one of water, organic compounds, metallorganic compounds, ionic liquids, and deep eutectic solvents and/or a mixture of water, organic compounds, metallorganic compounds, ionic liquids, and deep eutectic solvents.

8. The electrical and thermal conductive composite of claim 1, wherein the conduction promoter is a precursor and generates immiscible wetting agents during processing or under processing conditions.

9. The electrical and thermal conductive composite of claim 1, wherein a content of the conduction promoter is within a range of 0.1 wt % to 20 wt % of a polymer matrix.

10. The electrical and thermal conductive composite of claim 1, wherein the conduction promoter contains additional functional materials selected from a nanoparticle of a metal, metal oxides or ceramics, and carbon-based materials including a carbon tube, graphene, and graphene oxide.

11. The electrical and thermal conductive composite of claim 1, wherein the immiscible wetting agent is selected from a liquid form or a solid form that melts under a processing condition.

12. The electrical and thermal conductive composite of claim 1, wherein the immiscible wetting agent is selected from any inorganic or organic compound that wets the filler surface.

13. The electrical and thermal conductive composite of claim 1, wherein the immiscible wetting agent is selected from any inorganic or organic compound that wets the filler surface in the matrix of the base material.

14. The electrical and thermal conductive composite of claim 1, wherein an electrical conductivity and a thermal conductivity of the electrical and thermal conductive composite remains at a same thermal conductivity value as a conventional commercial product with a reduction of silver content by up to 50 wt %.

15. A method for producing an electrical and thermal conductive composite comprising:

mixing a base material with conductive particulate fillers, wherein the base material forms a matrix;

forming a polymeric suspension including a mixture of the base material and the conductive particulate fillers;

saturating a filler surface with a conduction promoter having an ultra-low particle filler volume fraction, wherein the conduction promoter is an immiscible wetting agent;

exerting capillary forces from the immiscible wetting agent upon the polymeric suspension;

inducing capillary bridging between the conductive particulate fillers; and

forming a conductive network including a percolated polymeric suspension and the induced capillary bridging.

16. The method for producing an electrical and thermal conductive composite of claim 15, further comprising mixing auxiliary components with the base material and the conductive particulate fillers.

17. The method for producing an electrical and thermal conductive composite of claim 16,

wherein the auxiliary components are selected from any type of liquid or powder and are configured as a functional additive to the electrical and thermal conductive composite, and

wherein the functional additive is selected from an organic solvent configured as a diluent, a prepolymer compound configured as a thickening agent, an inorganic nanoparticle configured as a thixotropic agent, a curing agent, and a catalyst.

18. The method for producing an electrical and thermal conductive composite of claim 15, wherein the base material is selected from at least one of polymers, biomacromolecular materials, organic-inorganic sol-gels, metals, metal oxide, ceramics and/or precursors or derivatives of polymers, biomacromolecular materials, organic-inorganic sol-gels, metals, metal oxide, and ceramics.

19. The method for producing an electrical and thermal conductive composite of claim 18,

wherein the base material further comprises polymer materials, and

wherein the polymer materials include at least one of polymer solutions or polymer suspensions, thermo-plastics, thermo-setting resins, rubbers, elastomers, polymer gels, hydrogels, organogels, or other types of macromolecular based materials or derivatives of polymer solutions or polymer suspensions, thermo-plastics, thermo-setting resins, rubbers, elastomers, polymer gels, hydrogels, organogels, or other types of macromolecular based materials.

20. The method for producing an electrical and thermal conductive composite of claim 15,

wherein the conductive particulate fillers are selected from at least one of metal, non-metal, metal oxide, ceramic powders or a derivative form of metal, non-metal, metal oxide, and ceramic powders, and

wherein each conductive particulate filler particle size is tens of a nanometer to a few millimeters.

21. The method for producing an electrical and thermal conductive composite of claim 15, wherein the conduction promoter is selected from at least one of water, organic compounds, metallorganic compounds, ionic liquids, and deep eutectic solvents and/or a mixture of water, organic compounds, metallorganic compounds, ionic liquids, and deep eutectic solvents.

22. The method for producing an electrical and thermal conductive composite of claim 15, wherein the conduction promoter is a precursor and generates immiscible wetting agents during processing or under processing conditions.

23. The method for producing an electrical and thermal conductive composite of claim 15, wherein a content of the conduction promoter is within a range of 0.1 wt % to 20 wt % of a polymer matrix.

24. The method for producing an electrical and thermal conductive composite of claim 15, wherein the conduction promoter contains additional functional materials selected from at least one of a nanoparticle of a metal, metal oxides or ceramics, and carbon-based materials including a carbon tube, graphene, and graphene oxide.

25. The method for producing an electrical and thermal conductive composite of claim 15, wherein the immiscible wetting agent is selected from a liquid form or a solid form that melts under a processing condition.

26. The method for producing an electrical and thermal conductive composite of claim 15, wherein the immiscible wetting agent is selected from any inorganic or organic compound that wets the filler surface.

27. The method for producing an electrical and thermal conductive composite of claim 15, wherein the immiscible wetting agent is selected from any inorganic or organic compound that wets the filler surface in the matrix of the base material.

28. The method for producing an electrical and thermal conductive composite of claim 15, wherein an electrical conductivity and a thermal conductivity of the electrical and thermal conductive composite remains at a same thermal conductivity value as a conventional commercial product with a reduction of silver content by up to 50 wt %.