Touch Panel Bezel Through Holes Conductive Glue Connection
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Solution Overview
Problem
Conventional touch panels face yield rate issues due to the fragility of ITO conductive films, which are prone to fracture from the height difference between the bezel and substrate, leading to open-circuit failures.
Innovation Solution
A touch panel structure with a substrate, touch sensor, bezel layer, signal wire layer, and protective layer, where through holes in the bezel layer are filled with conductive glue to connect signal and trace contacts, preventing the ITO conductive layer from bending and damage, and using a dummy pattern for improved transmittance and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the bezel thickness is reduced to few microns to achieve thinner touch panels, then the overall panel thickness is improved, but the height difference between bezel and substrate increases causing ITO conductive film fracture
Solution Approach 1:
The patent introduces an intermediate structure (recessed region with relief pattern) between the bezel and the ITO conductive film to mediate the height difference. This intermediate structure gradually transitions from the bezel surface to the substrate surface, preventing direct contact and stress concentration on the ITO film at sharp edges.
Solution Approach 2:
The patent creates a recessed region with relief pattern beforehand in the bezel layer to cushion the height difference before the ITO film encounters it. This pre-prepared gradual transition zone protects the fragile ITO film from sudden height changes that would cause fracture.
2Illumination intensity
If the ITO conductive film is made thinner to improve transparency, then the optical performance is improved, but the film becomes more fragile and prone to fracture
Solution Approach 1:
The patent designs the bezel structure with flexible relief patterns that can deform to accommodate the thin ITO film. The relief pattern creates a gradual slope rather than a sharp edge, allowing the thin film to bend smoothly without concentrating stress that would cause fracture.
3Reliability
If the sensing traces are extended to the periphery to improve contact coverage, then the electrical connection reliability is improved, but the traces are more exposed to height difference damage
Solution Approach 1:
The recessed region with relief pattern serves as an intermediary protective structure that shields the extended sensing traces from direct exposure to the height difference between bezel and substrate. The gradual transition protects the traces even when they extend to the periphery for better electrical connection.
Data Source
AI summary
A touch panel includes a substrate, a touch sensor, a bezel layer, a signal wire layer and a protective layer, which are superposed in order. The touch sensor has sensing traces and a dummy pattern. A trace contact at an end of each sensing trace is located at a margin of the substrate. The bezel layer is provided with through holes corresponding to the trace contacts. The signal wire layer includes signal wires arranged in a range of the bezel layer. A signal contact at an end of each signal wire is located correspondingly to one of the through holes. The through holes are filled with conductive glue to electrically connect the signal contacts and the trace contacts. The conductive glue is made of opaque conductive material with a color which is substantially identical to the bezel layer.