Patterned Overcoat Layer for Flexible Touch Screen Vias
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In roll-to-roll manufacturing of touch screen devices, forming reliable electrical connections between non-adjacent conductive layers is challenging due to complex registration requirements and the risk of defects like ribbing and pinholes, which increases costs and reduces productivity.
Innovation Solution
A method for creating self-forming vias on flexible substrates using a low surface energy material pattern that allows a liquid overcoat composition to de-wet and withdraw, leaving discrete areas for electrical connections, enabling precise control of coating thickness and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct printing of conductive material is used to form patterns, then manufacturing complexity is reduced and material waste is minimized, but variations in print thickness due to defects such as ribbing and pinholes occur, resulting in unacceptable conductivity variations and optical performance degradation
Solution Approach 1:
The patterning process is divided into two distinct steps: first forming a continuous conductive layer, then applying a resist material that is selectively removed to create the desired pattern. This segmentation allows each step to be optimized independently, avoiding the thickness variation problems of direct printing while maintaining process simplicity.
Solution Approach 2:
The continuous conductive layer is formed in advance before patterning. This preliminary action ensures a uniform conductive base layer is established, eliminating the thickness variation issues that would occur if patterning were performed directly on the conductive material in a single step.
2Manufacturing precision
If subtractive patterning with resist material and selective removal is used, then manufacturing precision of conductive patterns is improved, but device complexity increases and additional materials are required
Solution Approach 1:
Instead of directly patterning the conductive material, a separate resist material layer is applied and then selectively removed. This extraction of the patterning function into a distinct resist layer allows for precise pattern definition while keeping the conductive layer formation simple and uniform.
3Manufacturing precision
If multiple deposition steps are used to form patterns on flexible substrates, then manufacturing precision of pattern registration is improved, but productivity decreases and process time increases
Solution Approach 1:
The substrate continues to move continuously through the roll-to-roll process while the resist material is applied and patterned. This continuous action maintains high productivity while the resist layer provides the necessary registration precision for multi-layer constructions, eliminating the need for stopping and repositioning the substrate.
4Reliability
If precise registration between adjacent layers is maintained in multi-layer construction, then reliability of via formation is improved, but device complexity and process cost increase
Solution Approach 1:
The resist material layer serves as an intermediary between the continuous conductive layer and the overcoat layer. This intermediary layer provides a stable reference for registration, enabling reliable via formation in multi-layer constructions without requiring complex registration control systems. The resist layer's pattern defines the via locations precisely.
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 method enhances the reliability and cost-effectiveness of forming electrical connections in roll-to-roll processes, reducing defects and allowing for more precise control of coating thickness, thereby improving the manufacturing efficiency of touch screens and other opto-electronic devices.
Implementation Method 1
the overcoat solution de-wets and withdraws from the first region of the conductive surface
Data Source
Figure 1A~1C-1
Figure 1D~1E
Figure 2A~2E
AI summary
A composite article includes a conductive layer on at least a portion of a flexible substrate, wherein the conductive layer has a conductive surface. A patterned layer of a low surface energy material is on a first region of the conductive surface. An overcoat layer free of conductive particulates is on a first portion of a second region of the conductive surface unoccupied by the patterned layer. A via is in a second portion of the second region of the conductive surface between an edge of the patterned layer of the low surface energy material and the overcoat layer. A conductive material is in the via to provide an electrical connection to the conductive surface.