Touch Screen Insulating Layer for Bubble-Free Substrate Bonding
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Solution Overview
Problem
The production of air bubbles during the joining of upper and lower substrates in touch screen panels can lead to failures and reduce the reliability of the display device, as existing technologies do not effectively address the step caused by the black matrix, resulting in air bubbles and manufacturing yield issues.
Innovation Solution
Incorporating an insulating layer made of transparent organic material on the first substrate, which covers the conductive sensing cells and overlaps the concave portion formed by the black matrix on the second substrate, minimizing air bubble production by compensating for the step caused by the black matrix when the substrates are joined.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the black matrix is formed on the second substrate to define the non-touch active area, then the structural definition and boundary clarity are improved, but air bubbles are generated during substrate joining due to the step caused by the black matrix
Solution Approach 1:
An insulating layer is introduced as an intermediary element between the first substrate and the second substrate. This insulating layer specifically covers the step region created by the black matrix, providing a transition surface that eliminates the abrupt height difference. By doing so, it prevents air bubbles from forming during the bonding process while maintaining the clear boundary definition provided by the black matrix structure.
Solution Approach 2:
The insulating layer is formed in advance on the first substrate before the bonding process. This preliminary action creates a pre-compen sated surface that accounts for the step height difference caused by the black matrix. By preparing this insulating layer beforehand, the design ensures that no air bubbles will be trapped during the subsequent substrate joining operation.
2Strength
If the substrates are joined together to form the touch screen panel, then the structural integrity and functionality are improved, but air bubbles are trapped between the substrates reducing manufacturing yield
Solution Approach 1:
The insulating layer serves as a mediator that fills the step region between the black matrix and the substrate surface. This eliminates void spaces where air bubbles could be trapped during bonding, thereby maintaining high manufacturing yield while preserving the structural integrity achieved through proper substrate joining.
3Reliability
If the insulating layer is added to cover the step region, then air bubble production is minimized, but the device complexity increases
Solution Approach 1:
The insulating layer performs multiple functions simultaneously: it provides electrical insulation, fills the step region to prevent air bubbles, and creates a flat bonding surface. By combining these multiple functions into a single layer, the design achieves air bubble prevention without proportionally increasing device complexity, as the insulating layer is an integrated component rather than an additional separate element.
Data Source
AI summary
A touch screen panel includes first and second substrates disposed to face each other, conductive sensing cells in a touch active area on a first surface of the first substrate that faces the second substrate, a black matrix in a non-touch active area on a first surface of the second substrate that faces the first substrate, the non-touch active area being positioned outside the touch active area, an adhesive layer between the first and second substrates, the adhesive layer joining the first and second substrates together, and an insulating layer in the touch active area on the first substrate, the insulating layer covering the conductive sensing cells and overlapping a concave portion formed on the first surface of the second substrate by the black matrix.