Touch Substrate Pad Adhesion via Organic Interlayer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In capacitive touch screens, poor adhesion between film layers of pads leads to manufacturing challenges due to mismatched crystal lattices and hydrogen bonding during the patterning and heat treatment processes, affecting the reliability of the touch substrate.
Innovation Solution
The touch substrate design includes a first and second metal layer with an organic layer in between, featuring vias that allow for improved contact and adhesion, along with a cover layer and light shielding layer to enhance the bonding between the metal layers and the substrate, increasing the total contact area and firmness of the pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pad structure with metal layers is used, then the pad can conduct electrical signals, but the adhesion between film layers is poor due to lattice mismatch and hydrogen bonding
Solution Approach 1:
An organic layer is introduced as an intermediary between the first metal layer and the second metal layer. This organic layer acts as a mediator that prevents direct contact between metal layers, avoiding lattice mismatch and hydrogen bonding issues. The organic layer improves adhesion between film layers while maintaining electrical conductivity through the metal layers and their connections via vias.
Solution Approach 2:
The pad structure employs a composite material approach by combining metal layers with an organic layer. This composite structure integrates the electrical conductivity of metals with the adhesion benefits of organic materials, creating a multi-material system that resolves the adhesion problem while maintaining functional performance.
2Ease of manufacture
If the pad structure is simplified, then manufacturing is easier, but the firmness and adhesion of the pad deteriorates
Solution Approach 1:
The pad structure transitions from a planar two-dimensional configuration to a three-dimensional structure by introducing vias that penetrate through the organic layer. This dimensional change allows the second metal layer to connect with the first metal layer through the organic layer, enhancing pad firmness and adhesion while maintaining manufacturing feasibility through standard via formation processes.
Solution Approach 2:
The vias are formed within the organic layer, creating a nested structure where conductive pathways are embedded within the insulating organic material. This nesting approach allows the conductive elements to be contained within the pad structure, improving firmness without significantly increasing overall structural complexity.
3Reliability
If vias are formed in both metal layers and organic layer, then contact area increases improving adhesion, but the structure becomes more complex
Solution Approach 1:
The via structure is segmented into distinct components: first vias formed in the first metal layer, second vias formed in the organic layer, and third vias formed in the second metal layer. This segmentation allows each via type to be optimized independently for its specific function, increasing total contact area while managing structural complexity through modular design.
Data Source
AI summary
A touch substrate includes: a substrate, which includes a touch area and a bonding area on one side of the touch area; and a plurality of pads on the substrate, wherein the plurality of pads are arranged in the bonding area at intervals, wherein the pad includes a first metal layer, a first organic layer and a second metal layer, arranged in this order on the substrate, a first via is formed in the first metal layer, a second via is formed in the first organic layer, an orthographic projection of the first via on the substrate and an orthographic projection of the second via on the substrate do not overlap, a part of the first organic layer is in the first via, and a part of the second metal layer is in contact with the first metal layer through the second via.