Two-Sided Touch Sensor UV-Blocking Layer Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch screen technologies face challenges in precisely aligning conductive circuits on both sides of a transparent substrate due to the optically transparent nature of substrates and certain conductor materials, leading to issues like unintended exposure and increased costs with current solutions.
Innovation Solution
A method involving a UV-blocking layer applied to one surface of a transparent substrate, with photoresist layers on both sides, allowing for the formation of conductive patterns without unintended UV exposure, using materials like indium-tin-oxide (ITO) or antimony tin oxide (ATO) and metal layers, and a metal passivation layer to create a low-visibility conductive micro-mesh.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transparent substrate is used for two-sided patterning, then cost and complexity are reduced, but unintended UV exposure occurs on the opposite side
Solution Approach 1:
A UV-blocking layer is introduced as an intermediary between the transparent substrate and the photoresist on one side. This layer selectively blocks UV wavelengths that would cause unintended exposure on the opposite side while allowing the desired UV exposure to reach the photoresist from the same side, thus enabling single-substrate two-sided patterning without cross-contamination
Solution Approach 2:
The substrate system is segmented into multiple functional layers: the transparent substrate, the UV-blocking layer, and photoresist layers on both sides. This segmentation allows each layer to perform its specific function - the substrate provides mechanical support and optical transparency, the UV-blocking layer prevents harmful radiation transmission, and the photoresist layers receive controlled UV exposure for patterning
2Object-affected harmful factors
If two separate substrates are used to avoid unintended exposure, then UV exposure control is improved, but cost and alignment difficulty increase
Solution Approach 1:
Two separate substrate approaches are merged into a single substrate solution by integrating the UV-blocking functionality directly onto one side of the transparent substrate. This combines the benefits of UV exposure control with the advantages of a single-substrate structure, eliminating the need for separate substrates and their associated alignment and assembly complexities
3Object-affected harmful factors
If UV wavelength below 315 nm is used with photosensitive material, then substrate opacity is achieved, but material properties and process resistance deteriorate
Solution Approach 1:
Instead of changing the UV wavelength to below 315 nm which would compromise material reliability, the solution changes the parameter of the UV-blocking layer's wavelength selectivity. The layer is designed to block specific UV wavelengths that would cause unintended exposure while allowing other UV wavelengths to pass through for photoresist activation, thus maintaining both effectiveness and material compatibility
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
Enables the simultaneous patterning of conductive circuits on both sides of a transparent substrate, reducing costs and complexity, while maintaining optical performance and mechanical strength, and providing a low-visibility conductive micro-mesh for touch screens.
Implementation Method 1
a UV-blocking layer is applied to one surface of a transparent substrate. The photosensitive material is then applied on the UV absorbing layer on one side and directly on the substrate surface on an opposing side. The UV absorbing layer may be tuned to block the UV frequency from activating the photoresist.
Data Source
AI summary
A touch sensor having conductive circuits on both surfaces of a substrate is fabricated by including UV-blocking material into the substrate or depositing UV-blocking layer on the substrate. This can be used for fabricating sensors having transparent conductor circuits, or having metallic circuits, which are opaque to visible light. Photoresist is applied to both surfaces of the substrate and patterns are transferred to the photoresist by exposure to UV radiation. The UV-blocking layer prevents UV-radiation applied to one side from exposing the opposite side. If desired, both photoresist layers may be exposed simultaneously by splitting one UV beam.