Touch Panel Electrode Stress Mitigation via Tensile Insulation
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Solution Overview
Problem
Conventional touch panels using indium tin oxide (ITO) for sensing electrodes are brittle and prone to breakage when bent, limiting their flexibility and reliability, especially when a large bending angle is applied, such as when the panel is folded.
Innovation Solution
A touch panel design that includes a substrate with transparent and opaque regions, featuring sensing electrodes composed of a first metal layer, a first insulation layer with tensile stress, and a first transparent conductive layer, which are electrically connected, and conducting wires, enhancing the bending ability by mitigating compressive stress through the insulation layer's tensile stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO is used to form sensing electrodes for transparency and conductivity, then transparency and conductivity are improved, but bending ability deteriorates because ITO is brittle and has compressive stress
Solution Approach 1:
The patent uses a composite material structure consisting of a metal layer, insulation layer, and transparent conductive layer. The metal layer provides mechanical strength and tensile stress to counteract ITO's compressive stress, the insulation layer provides tensile stress and protects the metal layer, and the transparent conductive layer maintains transparency and conductivity. This composite structure resolves the contradiction between transparency/conductivity and bending ability.
Solution Approach 2:
The patent changes the stress parameter of the sensing electrode structure by introducing an insulation layer with tensile stress. This tensile stress counteracts the compressive stress of the ITO layer, preventing crack formation during bending. The stress parameter transformation from compressive to tensile balance enables the electrode to withstand bending while maintaining electrical properties.
2Adaptability or versatility
If a large bending angle is applied to the touch panel, then flexibility is improved, but the sensing electrodes break due to compressive stress in ITO
Solution Approach 1:
The patent applies the counterweight principle by introducing an insulation layer with tensile stress to counterbalance the compressive stress in the ITO layer. When the panel is bent, the tensile stress from the insulation layer counteracts the compressive stress that would otherwise cause the brittle ITO to crack, thereby maintaining electrode integrity while enabling large bending angles.
Solution Approach 2:
The insulation layer acts as an intermediary between the metal layer and the transparent conductive layer. It provides mechanical support with tensile stress to protect the brittle ITO from breaking during large bending angles, while also ensuring electrical insulation and maintaining the overall structural integrity of the sensing electrode.
3Adaptability or versatility
If the touch panel is folded, then portability is improved, but abnormal operation occurs due to broken sensing electrodes
Solution Approach 1:
The composite structure of metal layer + insulation layer with tensile stress + transparent conductive layer ensures that the sensing electrodes can withstand the mechanical stress of folding without breaking. This maintains normal touch panel operation while enabling folded configurations for improved portability.
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 design improves the bending reliability and flexibility of the touch panel, allowing it to withstand larger bending angles without cracking, thereby enhancing its durability and functionality.
Implementation Method 1
the bending ability of the stack of the first transparent conductive layer, the first insulation layer and the first metal layer can be improved by disposing the first insulation layer with tensile stress between the first transparent conductive layer and the first metal layer
Data Source
AI summary
A touch panel is provided and includes a substrate and a plurality of sensing pads disposed on the substrate. Each sensing pad includes a metal layer, an insulation layer and a transparent conductive layer. The insulation layer is disposed between the metal layer and the transparent conductive layer, and the metal layer is in contact with the transparent conductive layer.