Layered Contacting System for Flexible Heating Elements
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Solution Overview
Problem
Existing methods for producing flexible heating elements with electrical conductive particles face issues such as significant contact resistance, 'hot spots', reduced flexibility, and unpredictable heating output due to varying mechanical loads and thermal expansion coefficients, especially when using sewing, gluing, or embedding conductive wires within the polymer matrix.
Innovation Solution
A method for producing a contacting system with a layered composite of a carrier material, metallic conductor, and electrically conductive layer, where the bond between the carrier material and metallic conductor is formed first, followed by integration with the conductive layer, ensuring stable and flexible contact without encasing the metallic conductor, allowing for uniform and reliable electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wires are sewn onto the heating element, then the contacting process is quick and uncomplicated, but significant contact resistance occurs and hot spots form
Solution Approach 1:
An adhesive layer is introduced as an intermediary substance between the wire and the heating element surface. This adhesive layer fills gaps and irregularities, ensuring intimate contact between the wire and the conductive particles in the heating element, thereby reducing contact resistance while maintaining ease of manufacture.
Solution Approach 2:
The contacting system uses a composite structure consisting of the wire, adhesive layer, and heating element surface with conductive particles. This composite approach combines the mechanical strength of the wire with the conformability and electrical conductivity of the adhesive and heating element, resolving the contradiction between simple application and low contact resistance.
2Reliability
If conductive wires are embedded during film production, then reliable all-round contact is ensured, but flexibility is greatly reduced
Solution Approach 1:
The contacting system is segmented into distinct functional layers: the flexible heating element base layer, the adhesive layer for electrical contact, and the wire conductor. This segmentation allows each layer to perform its optimal function - the base layer maintains flexibility, the adhesive ensures reliable contact, and the wire provides electrical conduction, resolving the contradiction between contact reliability and flexibility.
Solution Approach 2:
The heating element uses a thin-film structure with the wire positioned on the surface rather than embedded throughout the bulk material. This thin-film approach maintains the overall flexibility of the heating element while ensuring reliable electrical contact through the adhesive layer, avoiding the rigidity associated with full embedding.
3Reliability
If conductive lacquer is used to glue wires, then permanent material-to-material contact is established, but flexibility is reduced due to high filling requirements
Solution Approach 1:
The adhesive layer's physical and chemical parameters are optimized to balance conductivity and flexibility. By controlling the composition, viscosity, and curing characteristics of the adhesive, the system achieves permanent electrical contact while maintaining sufficient flexibility for practical applications, resolving the contradiction between permanent contact and flexibility.
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 solution achieves high stability and flexibility in the contacting system, preventing 'hot spots' and maintaining consistent heating performance across different mechanical loads, while avoiding the limitations of encasing conductive materials, ensuring reliable and uniform power distribution.
Implementation Method 1
an electrically conductive layer (1), wherein in the method first a bond (3) is produced between the carrier material (2) and the metallic conductor (3) and then the bond (3) is joined to the electrically conductive layer (1)
Implementation Method 2
Heating elements based on plastics and suitable electrically conductive particles (soot, graphite, carbon fibers, metals, metal oxides or mixtures of these components) are already known
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a contacting system, particularly for electrically contacting essentially planar heating elements. The invention also relates to a corresponding heating element. Lastly, the invention relates to a method for producing a contacting system and to a method for producing a heating element.