Hybrid Printed Heater with Segmented Bridge Pattern
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Solution Overview
Problem
Conventional electric heating devices for automotive applications face challenges in achieving uniform heat distribution, mechanical robustness, and cost efficiency due to the limitations of copper wires and high silver load inks, which result in reduced heating power and increased material fragility.
Innovation Solution
A method involving a sheet of electrically conductive material with a predetermined line pattern and bridge members, where the adhesive is cured except under the bridge members, allowing for high current density and integration close to surfaces with improved handling properties, using materials like copper, copper alloys, or conductive textiles with a positive temperature coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heating wires (copper) are used, then high current density can be carried, but the heating device becomes noticeable and causes hot spots
Solution Approach 1:
The heating function is segmented from the current conduction function. A separate resistive heating trace (printed pattern) is introduced to provide heating, while the copper feed lines are designed to minimize their visual and thermal impact. The heating trace is distributed across the surface in a pattern that avoids hot spots
Solution Approach 2:
Different regions of the heating device have different functions and properties. The feed lines are optimized for current conduction with minimal heating, while the distributed printed pattern provides uniform heating across the surface. The adhesive layers and carrier material are selected to have specific thermal and electrical properties for their local function
2Manufacturing precision
If high silver load inks are used for printed heating traces, then uniform heating can be achieved, but mechanical robustness decreases and cost increases
Solution Approach 1:
A composite structure is used combining multiple materials: copper feed lines for high conductivity, resistive ink for heating, and adhesive layers for bonding. The printed heating trace uses a resistive material with optimized properties rather than pure silver, achieving uniform heating while maintaining mechanical flexibility and reducing cost
Solution Approach 2:
The electrical resistance, thickness, and material composition of the printed heating trace are optimized to achieve uniform temperature distribution. The sheet resistance is controlled to provide even heating without requiring high silver content, thus maintaining mechanical robustness
3Volume of moving object
If the heating device is miniaturized, then integration is improved, but handling and installation become more difficult
Solution Approach 1:
The heating traces and feed lines are pre-formed on a flexible carrier substrate with adhesive layers. The bridge members are pre-positioned to facilitate connection. This preliminary configuration on the carrier makes the miniaturized device easy to handle and install as a complete unit
Solution Approach 2:
A flexible carrier substrate with adhesive layers serves as an intermediary that holds all components in place during handling and installation. The bridge members act as intermediaries for electrical connection, making the device easy to integrate into the application
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
This method enables the production of electric heating devices with high current density and uniform heating, improved mechanical robustness, and cost-effectiveness, suitable for automotive applications such as steering wheels and door panels, while avoiding the limitations of conventional heating wires and inks.
Implementation Method 1
The predetermined line pattern comprises an electrically conductive line and at least two electrically highly conductive feed lines
Implementation Method 2
depositing a layer of curable adhesive material onto a surface of the flexible carrier
Implementation Method 3
Electrically resistive inks exhibiting a positive temperature coefficient (PTC), which is desirable as such materials are inherently self-limiting
Data Source
AI summary
A method of producing an electric heating device, in particular for automotive application, includes steps of: cutting through a sheet of electrically highly conductive material of appropriate thickness for obtaining a predetermined line pattern having at least one electrically conductive line with electrically conductive bridge members interconnecting portions of the at least one electrically conductive line; depositing a layer of curable adhesive material onto a surface of a dielectric, planar, flexible carrier; placing the obtained line pattern onto the layer of adhesive material; curing the adhesive material below the line pattern with the exception of the adhesive material below the bridge members; cutting through each bridge member at all ends between portions of the at least one electrically conductive line interconnected by the respective bridge member; and removing the cut bridge members.