Film-Type Touch Sensor Electrode Pattern Sheet Resistance
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Solution Overview
Problem
Existing touch sensors face challenges in achieving low sheet resistance while maintaining high resolution, large area, and small thickness, with indium tin oxide (ITO) easily cracking on flexible substrates and degrading transmittance when thickness is increased.
Innovation Solution
A method involving a film-type touch sensor with a separation layer, electrode pattern layer, and protection layer, where the electrode patterns are formed using multiple conductive layers, including a transparent metal oxide layer and a thin-film metal layer, to reduce sheet resistance and withstand high-temperature processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO thickness is increased to reduce sheet resistance, then sheet resistance decreases, but transmittance is degraded and product thickness increases
Solution Approach 1:
The patent uses a composite structure consisting of a first transparent conductive layer (ITO) and a second transparent conductive layer (AZO) stacked in sequence. This composite material approach allows the first layer to provide low sheet resistance while the second layer maintains high transmittance, achieving sheet resistance of 200Ω/sq or less with transmittance of 85% or more, thus resolving the contradiction between reducing sheet resistance and maintaining transmittance.
2Reliability
If ITO thickness is increased to reduce sheet resistance, then sheet resistance decreases, but product thickness increases
Solution Approach 1:
The patent employs a composite structure with a first transparent conductive layer (ITO) and a second transparent conductive layer (AZO) where each layer has optimized thickness. The ITO layer provides conductive properties while the AZO layer adds minimal thickness while maintaining transparency. This composite approach achieves sheet resistance of 200Ω/sq or less with total thickness of 50nm or less, resolving the contradiction between reducing sheet resistance and maintaining small product thickness.
3Adaptability or versatility
If film layer is attached on substrate, then flexibility is improved, but film layer deforms due to high-temperature process
Solution Approach 1:
The patent changes the parameter of substrate material from flexible polymer to rigid glass substrate. This parameter change allows the structure to withstand high-temperature processes (such as sputtering and annealing) without deformation, while still achieving flexibility through subsequent lamination of flexible films. The glass substrate provides thermal stability during manufacturing while the final product can be made flexible through additional layers.
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 solution achieves a low sheet resistance of 10 Ω/square or less and high transmittance of 85% or more, enabling a high-performance touch sensor with improved sensitivity for large-area and high-resolution applications, including fingerprint recognition.
Implementation Method 1
a first transparent conductive layer and a second transparent conductive layer which are stacked on the first transparent conductive layer in this sequence
Implementation Method 2
both having a transmittance of 85% or more
Data Source
AI summary
The present invention relates to a high-performance film-type touch sensor that has a low sheet resistance and can have a high resolution, a large area, and a small thickness, and a method of fabricating the same. In the high-performance film-type touch sensor which is peeled off from a substrate and to which a base film is bonded, at least a separation layer, an electrode pattern layer, and a protection layer are sequentially stacked on the base film, and one or more of first and second electrode patterns arranged in different directions on the separation layer are formed of a plurality of conductive layers to reduce sheet resistance.