Conductive Node Adhesive Composition for Resistance Welding
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Solution Overview
Problem
Weldable sealant and adhesive formulations with higher green-state viscosities face challenges in resistance welding due to the inability of conductive fillers to bridge the gap between substrates effectively, leading to increased electrical resistance and poor weld quality, as non-conductive fibers and encapsulations hinder the material's ability to 'squeeze-out' and form a conductive path.
Innovation Solution
Incorporating discrete solid carbon steel spheres with diameters between 0.20 mm and 2.5 mm within an epoxy-based material of high viscosity, which form nodes for welding and remain discrete to maintain the material's properties, allowing for improved weldability without the need for shunt means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If higher green-state viscosity is used to improve mechanical properties and handling, then mechanical strength and processing improve, but the ability to squeeze-out and form conductive paths deteriorates
Solution Approach 1:
The patent changes the physical state parameter of the conductive filler from fine powder to discrete solid spheres with diameter >0.20mm. This parameter change allows the spheres to remain suspended in high-viscosity materials without being fully encapsulated, enabling them to bridge gaps and form conductive paths during welding while maintaining the high viscosity needed for mechanical strength and handling properties.
2Strength
If conductive fillers are encapsulated by non-conductive materials to improve strength and corrosion resistance, then mechanical properties improve, but electrical conductivity deteriorates
Solution Approach 1:
The patent segments the conductive filler into discrete solid spherical particles rather than using continuous or finely distributed conductive material. These segmented spheres are large enough (0.20-2.5mm diameter) to remain as distinct entities within the non-conductive epoxy matrix, allowing them to protrude through the material during welding and form conductive bridges without being fully encapsulated by the non-conductive polymer.
Solution Approach 2:
The patent creates a composite structure where discrete conductive metal spheres are distributed within a non-conductive epoxy matrix. The spheres are present at 1-30% by volume and maintain their metallic conductivity while being embedded in the polymer matrix, creating a composite material that combines the mechanical properties of the epoxy with the electrical conductivity of the metal spheres at the weld interface.
3Stability of the object's composition
If non-conductive fibers are added to control flow and improve dimensional stability, then processing and dimensional stability improve, but the ability to form conductive paths deteriorates
Solution Approach 1:
The patent changes the form parameter of the conductive filler from fibrous to spherical geometry. The spherical shape with diameter 0.20-2.5mm allows the conductive particles to roll and reposition during welding, forming conductive paths without being hindered by the flow-control properties of fibers. The spheres maintain dimensional stability while enabling electrical conductivity at the weld interface.
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 formulation enables weldability of high-viscosity sealant and adhesive materials, achieving low resistance electrical pathways and enhanced mechanical properties, such as lap shear strengths greater than 1MPa, while maintaining structural integrity and handling benefits.
Implementation Method 1
the discrete spheres form at least one node for welding the material to a surface... achieve low resistance electrical pathways
Implementation Method 2
an epoxy-based material having a viscosity of greater than 50,000 Pa·s in its green state at room temperature
Implementation Method 3
Only during the pressure applied by the resistance welding and the displacement of the adhesive/sealant from the applied pressure does the material become thin enough to engage the conductive materials
Data Source
AI summary
A weldable adhesive or sealant formulation comprising a plurality of discrete solid metallic portions within a material having a viscosity of greater than 10,000 Pa s in its green state and at room temperature.