Touch Panel Adhesive Seepage into Acute-Angled Silver Mesh Cells
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Solution Overview
Problem
Touch panels with silver mesh electrodes of lozenge or parallelogrammatic shape suffer from seepage failures and ion migration due to the inability of optically clear adhesives (OCAs) to effectively cover acute-angled portions, leading to resistance changes and short circuits.
Innovation Solution
A touch panel design incorporating fine silver lines with a width of 4 μm or less and a specific adhesive with a loss coefficient tan δ of 0.13 or greater and storage elastic modulus of 8.9×10^4 Pa or less, which allows the adhesive to seep into acute-angled portions, preventing water entry and ion migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the widthwise dimension of fine silver lines is reduced to increase visibility, then image quality improves, but ion migration occurs leading to resistance changes and short circuits
Solution Approach 1:
The patent applies different properties to different parts of the adhesive layer. The adhesive has high loss coefficient (tan δ ≥ 0.13) and low storage elastic modulus (≤ 8.9×10^4 Pa) specifically in regions corresponding to acute-angled portions of parallelogrammatic cells, enabling targeted seepage into these critical areas to prevent ion migration while maintaining overall structural integrity
Solution Approach 2:
The patent changes the physical parameters of the adhesive material by specifying a loss coefficient tan δ of 0.13 or greater and storage elastic modulus of 8.9×10^4 Pa or less. These parameter changes enable the adhesive to achieve appropriate viscosity and flow characteristics that allow it to seep into acute-angled portions effectively
2Strength
If optically clear adhesive is applied to silver mesh transparent electrode with parallelogrammatic cells, then electrode bonding is achieved, but seepage failure occurs in acute-angled portions
Solution Approach 1:
The patent modifies the adhesive's physical parameters by specifying loss coefficient tan δ ≥ 0.13 and storage elastic modulus ≤ 8.9×10^4 Pa, which transform the adhesive's flow and bonding characteristics to enable effective seepage into acute-angled portions while maintaining adequate bonding strength
Solution Approach 2:
The patent employs an adhesive with dynamic viscoelastic properties characterized by high loss coefficient and low storage elastic modulus, allowing the adhesive to dynamically adapt its viscosity during application - flowing into acute-angled portions during application then maintaining bonding strength after curing
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
The solution effectively prevents resistance value changes and short circuits in the touch panel, ensuring excellent visibility and reliability even with fine silver lines, by ensuring the adhesive covers the electrodes effectively.
Implementation Method 1
the OCA fails to enter into the acute-angled portions of the cells, i.e., a seepage failure occurs
Data Source
AI summary
A touch panel and a display device are disclosed. Either a cell or a cell, which is formed by the intersections of silver fine wires which form either first electrodes or second electrodes, forms parallelogram shapes (preferably rhomboids), having opposite angles wherein intersection angles are obtuse angles and intersection angles are acute angles. The first electrodes and/or the second electrodes have an adhesive (OCA) deployed thereupon, which has a loss coefficient (tan δ) of 0.13 or more at 140° C. and 1 Hz, and a reserve elasticity of 8.9×104 Pa or less at 25° C. and 1 Hz.