Blocking Layers for Double Sided Touch Sensors
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Solution Overview
Problem
Existing touch sensor panel fabrication methods, such as lithography and laser ablation, face issues with light exposure and damage to underlying layers, particularly when using materials like indium tin oxide, which can alter feature sizes and damage substrates due to unwanted light penetration or high ablation fluence values.
Innovation Solution
The implementation of blocking layers on the touch sensor structure to prevent light exposure from both sides during lithography and laser ablation processes, using materials with specific transmittance properties to shield unwanted wavelengths and prevent damage to underlying layers, allowing for precise patterning without altering the properties of the substrate or conductive films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lithography is used to pattern drive and sense lines, then multiple features can be patterned at once reducing fabrication time, but light exposure penetrates to underlying layers and alters their properties
Solution Approach 1:
A blocking layer is introduced as an intermediary between the light source and the underlying layers during lithography. This blocking layer absorbs or reflects the exposure light, preventing it from penetrating to and altering the properties of underlying layers such as ITO, while still allowing the lithography process to pattern multiple features simultaneously.
Solution Approach 2:
The substrate structure is segmented into multiple layers with distinct functions: the blocking layer is positioned between the light source and the underlying functional layers. This segmentation allows the blocking layer to specifically address the light penetration issue without affecting the overall lithography productivity.
2Manufacturing precision
If laser ablation is used to achieve finer patterns for drive and sense lines, then pattern precision is improved, but the laser beam damages underlying layers or substrate when material has high ablation fluence value
Solution Approach 1:
The blocking layer serves as a protective intermediary positioned between the laser beam and the underlying substrate or layers. It absorbs or reflects the laser energy, preventing the high ablation fluence from damaging the substrate while still allowing precise patterning of the ITO material to be achieved.
Solution Approach 2:
The blocking layer converts the potentially harmful laser energy that would otherwise damage the substrate into a beneficial protective function. By absorbing or reflecting the excess laser energy, the blocking layer protects the underlying layers while the necessary laser ablation for fine patterning can proceed.
3Reliability
If transparent conductive material like ITO is used for drive and sense lines, then electrical conductivity is improved, but the material requires high ablation fluence that can damage underlying layers
Solution Approach 1:
The blocking layer acts as a protective intermediary that specifically addresses the high ablation fluence requirement of ITO. It absorbs or reflects the excessive laser energy during patterning, preventing damage to underlying layers while allowing the ITO to maintain its excellent electrical conductivity properties in the final device.
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 enables the fabrication of compact touch sensors that maintain the integrity of underlying layers and substrates, ensuring accurate feature sizes and preventing damage during the manufacturing process, thereby enhancing the reliability and performance of touch sensor panels.
Implementation Method 1
The one or more blocking layers can be formed to block underlying layers from exposure to certain wavelengths of light
Implementation Method 2
The one or more blocking layers can be formed to block underlying layers from penetration of a laser beam that can cause damage
Data Source
AI summary
Compact touch sensors for touch sensitive devices and processes for forming the touch sensors are disclosed. The touch sensor structure can include a substrate, one or more underlying layers disposed on the substrate, one or more blocking layers disposed on the substrate or on one or more underlying layers, and one or more patterned layers disposed on the underlying layers or blocking layers. The one or more blocking layers can be configured to block underlying layers from exposure to certain wavelengths of light or from penetration of a laser beam that can cause damage. Additionally, the one or more underlying layers can be multi-functional, including the ability to block one or more light sources.