Conductive Paste Using Wetting Agent to Lower Percolation Threshold
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Solution Overview
Problem
Conventional high electrical and thermal conductive polymer composites have a high resistivity and a relatively high percolation threshold, making it difficult to enhance conductivity and lower filler content, especially with the use of expensive and difficult-to-handle nanomaterials.
Innovation Solution
A novel jamming gelation technique is employed using an immiscible wetting agent to induce capillary bridging between conductive particulate fillers, reducing the percolation threshold and enhancing conductivity at a lower filler volume fraction, allowing for the formation of a highly conductive network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive polymer composites are used, then electrical and thermal conductivity can be achieved, but the percolation threshold is high and resistivity remains high
Solution Approach 1:
The patent introduces an immiscible wetting agent as an intermediary substance that forms capillary bridges between conductive filler particles. This wetting agent mediates the interaction between the filler particles and the polymer matrix, enabling the formation of a conductive network at much lower filler concentrations. The capillary bridges created by the wetting agent act as conduits that enhance electrical and thermal conductivity while reducing the required filler volume fraction from conventional levels to below 5 vol%.
Solution Approach 2:
The patent changes the physical and chemical parameters of the composite system by introducing a wetting agent with specific surface tension properties. This alters the interfacial interactions between filler particles and matrix, enabling capillary condensation and bridge formation. The parameter change in surface energy and wettability allows the system to achieve percolation at ultra-low filler concentrations, transforming the conventional high-resistivity composite into a highly conductive material.
2Reliability
If nanomaterials such as single-wall nanotubes and silver nanowires are used to lower percolation threshold, then conductivity can be enhanced, but handling difficulty and cost increase significantly
Solution Approach 1:
The patent replaces expensive, difficult-to-handle nanomaterials (such as single-wall nanotubes and silver nanowires) with conventional, inexpensive conductive filler particles. The immiscible wetting agent compensates for the lower intrinsic conductivity of these conventional fillers by forming capillary bridges that enhance charge and heat transfer. This substitution dramatically reduces material cost and simplifies handling while achieving comparable or superior conductivity at lower filler loadings.
Solution Approach 2:
The wetting agent serves as a mediator that enables conventional filler particles to perform functions previously only achievable with expensive nanomaterials. By forming capillary bridges, the wetting agent creates efficient conduction pathways that compensate for the lower aspect ratio and surface area of conventional fillers, eliminating the need for difficult-to-handle nanomaterials while maintaining high conductivity.
3Reliability
If filler content is reduced to lower percolation threshold, then conductivity can be enhanced, but manufacturing process complexity increases
Solution Approach 1:
The immiscible wetting agent performs multiple functions simultaneously: it wets the filler surface, forms capillary bridges, and self-organizes into a network structure that enables conduction. This self-service capability eliminates the need for complex external processing steps to create conductive pathways. The system self-assembles the conductive network during mixing and curing, simplifying the manufacturing process despite the ultra-low filler content and unique rheological behavior.
Solution Approach 2:
The introduction of the wetting agent changes the rheological and surface energy parameters of the composite system, enabling self-organization and capillary bridge formation during standard mixing and curing processes. These parameter changes allow the conductive network to form automatically without requiring additional processing steps, maintaining manufacturing simplicity even at ultra-low filler loadings below 5 vol%.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The jamming gelation technique significantly lowers the percolation threshold from approximately 20% to less than 5% filler volume fraction, enhancing electrical and thermal conductivity while being compatible with conventional manufacturing processes and cost-effective.
Implementation Method 1
A mixture of the base material, conductive particulate fillers, and the immiscible wetting agent form a particle-filled polymeric suspension that undergoes capillary forces exerted by the immiscible wetting agent. Due to the capillary forces, capillary bridges are arranged between the conductive particulate fillers.
Implementation Method 2
Percolation of the particle-filled polymeric suspension and the presence of capillary bridges form a conductive network that is highly conductive and enhances the conductivity of the composite.
Data Source
AI summary
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.