Flexible Printed Wiring Board Heater for Automotive Windshields
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Solution Overview
Problem
Conventional film-like heaters for automotive windshields and camera lenses require multiple manufacturing steps, including bonding a soaking plate, which reduces thermal conductivity and reliability due to the use of pressure-sensitive adhesive layers and necessitates additional components like wire harnesses.
Innovation Solution
A flexible printed wiring board heater with a base film, a first metal foil forming a heater circuit, and a second metal foil forming a heat conductive foil portion, where the heat conductive foil portion is integrated directly onto the base film, eliminating the need for a separate soaking plate and wire harness, and reducing manufacturing steps through etching and laminating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a soaking plate is bonded to the second insulating film using a pressure-sensitive adhesive layer, then the heating temperature distribution becomes uniform, but the thermal conductivity decreases and the bonding reliability is compromised
Solution Approach 1:
The soaking plate and the second insulating film are merged into a single integrated structure where the soaking plate serves dual functions as both a heat distribution element and the insulating film itself. This eliminates the need for separate bonding layers while maintaining both uniform heating and reliable structural integrity.
Solution Approach 2:
The pressure-sensitive adhesive layer is extracted and removed from the structure. By eliminating this intermediate bonding layer, the patent achieves direct thermal contact between components while maintaining structural reliability through the integrated soaking plate design that performs both heating and insulating functions.
2Reliability
If multiple components including soaking plate and wire harness are used, then the heater functionality is complete, but the manufacturing steps increase and device complexity increases
Solution Approach 1:
Multiple functional components are merged into the flexible printed wiring board structure. The soaking plate, insulating films, and heating elements are integrated into a single multi-layer FPCB structure, eliminating the need for separate wire harnesses and reducing the number of discrete components while maintaining complete heater functionality.
Solution Approach 2:
The flexible printed wiring board serves multiple functions simultaneously: it provides electrical connections for heating elements, acts as the soaking plate for uniform heat distribution, and serves as the insulating film structure. This multi-functionality reduces component count while ensuring reliable heater operation.
3Ease of manufacture
If pressure-sensitive adhesive layers are used between heater wire and soaking plate, then the components can be assembled, but the thermal conductivity is reduced
Solution Approach 1:
The pressure-sensitive adhesive layers are extracted and removed from the thermal path. The integrated FPCB structure provides direct thermal contact between the heating elements and the soaking plate regions, eliminating thermal resistance introduced by adhesive layers while maintaining assembly capability through the laminated FPCB construction process.
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 configuration enhances thermal conductivity, reduces manufacturing complexity, and increases reliability by integrating the heat conductive foil directly onto the base film, allowing for uniform heating and flexible attachment to curved surfaces.
Implementation Method 1
the first metal foil forms a heater circuit portion that generates heat when energized
Implementation Method 2
the second metal foil forms a heat conductive foil portion that maintains a non-energized state
Data Source
AI summary
Provided is a heater which includes a flexible printed wiring board, in which the flexible printed wiring board includes a base film, a first metal foil, and a second metal foil, the first metal foil forms a heater circuit portion that generates heat when energized, on a first surface of the base film, and the second metal foil forms a heat conductive foil portion that maintains a non-energized state, on a second surface of the base film.