Capacitive Touch Sensor Injection Molding and Coating
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Solution Overview
Problem
The production of capacitive touch sensors involves complex assembly processes and is prone to contamination and damage during handling, with existing methods not ensuring a simple, high-quality, and durable product.
Innovation Solution
A method where a plastic film carrying sensor electrodes and conductor tracks is placed in an injection molding tool cavity, with a polycarbonate or polymethyl methacrylate carrier plate injected on the opposite side, forming a component that is then coated with a scratch-resistant material in a second cavity, eliminating separate assembly steps and enhancing durability and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate assembly processes are used to connect sensor electrodes to the carrier plate, then flexibility in component manufacturing is maintained, but the production process becomes complex and prone to contamination and damage
Solution Approach 1:
The patent combines the sensor electrode carrier film and the carrier plate into a single integrated component through injection molding. The carrier plate is molded directly onto the carrier film in one manufacturing step, eliminating separate assembly processes for connecting sensor electrodes to the carrier plate, thus simplifying production and reducing contamination risks
2Device complexity
If the carrier plate is molded directly onto the sensor electrodes, then assembly complexity is reduced, but the sensor electrodes may be damaged or shifted during high-pressure injection
Solution Approach 1:
The patent uses the carrier film as a protective cushioning layer between the sensor electrodes and the injection-molded carrier plate. The carrier film absorbs the impact and pressure during the injection molding process, preventing damage and position shifts of the sensor electrodes while still allowing the carrier plate to be molded directly onto them
3Strength
If a scratch-resistant coating is applied to the carrier plate, then durability is improved, but the production process requires additional steps
Solution Approach 1:
The patent combines the carrier plate and the scratch-resistant coating into a single integrated component through a two-shot injection molding process. The first shot creates the carrier plate, and the second shot applies the scratch-resistant coating material directly onto it, eliminating separate coating steps and simplifying production while maintaining durability
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 approach simplifies the production process, reduces the risk of contamination and damage, and results in a high-quality, durable touch sensor with improved dimensional accuracy and chemical resistance, suitable for use in harsh environments like vehicle control panels.
Implementation Method 1
with the polycarbonate in the contact area reacting plastic is injected
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
The invention relates to a method for producing a capacitive contact sensor and to a capacitive contact sensor having a carrier plate (4) made of plastic, the front surface (7) thereof initiating a switching process when contacted and the rear surface thereof having one or more capacitive sensor electrodes disposed thereon and connected via conductors to analysis electronics. The regions on the front surface (7) of the carrier plate (4) opposite the sensor electrodes thereby form contact zones (5). A plastic film (1) supporting the sensor electrodes and conductors is placed on a first side wall of a cavity of an injection molding tool, wherein the sensor electrodes face the first side wall, and then a polycarbonate forming the carrier plate (4) is injected into the cavity on the side of the plastic film (1) facing away from the sensor electrodes. The cavity is then expanded, forming a gap on the side facing away from the plastic film (1) and the gap is injected with a further plastic reacting with the polycarbonate in the contact region and forming a scratchproof coating (3).