Touch Panel Terminal Groove Design for Reliable Electrical Connection
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Solution Overview
Problem
The manufacturing yield of touch panels is reduced due to difficulties in ensuring reliable electrical connection between electrode-side and circuit-side terminal portions, caused by conductive material not physically contacting conductive balls in the anisotropic conductive film, resulting from excess conductive material not being properly removed from the substrate surface.
Innovation Solution
A touch panel design where the dimensions of the conductive balls and grooves are optimized such that the conductive balls can easily come into contact with the conductive material, with the average diameter of the balls being either equal to or less than the groove width and greater than the depth of the space left by the conductive material, or the balls being larger and deformed to fit within the groove, ensuring a conductive path between the terminal portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conductive material is applied excessively onto the substrate surface to ensure groove filling, then the groove can be fully filled with conductive material, but the conductive material remaining on the substrate surface prevents physical contact with conductive balls, reducing manufacturing yield
Solution Approach 1:
The patent applies a release agent to the substrate surface before applying conductive material. This preliminary action creates a non-stick surface that prevents conductive material from adhering to the substrate, ensuring that excess material can be easily removed and the groove-filling process does not compromise electrical connection reliability.
Solution Approach 2:
The patent systematically removes excess conductive material from the substrate surface after groove filling. This extraction process separates the useful conductive material (inside grooves) from harmful excess material (on surface), preventing interference with conductive ball contact while maintaining complete groove filling.
2Productivity
If the number of manufacturing processes is reduced by forming grooves and filling them in one operation, then productivity increases, but it becomes difficult to ensure proper contact between conductive material and conductive balls
Solution Approach 1:
The release agent application is performed as a preliminary step before the one-step groove formation and filling operation. This enables the simplified manufacturing process to proceed while still allowing for precise control of conductive material placement and easy removal of excess material to ensure proper contact.
Solution Approach 2:
The patent modifies the surface properties of the substrate by applying a release agent, changing its adhesion parameters. This allows the conductive material to be applied in excess without sticking, and enables precise control over where the material remains (in grooves) versus where it is removed (from surface), maintaining contact precision in the simplified process.
3Reliability
If conductive material is removed from the substrate surface to enable contact with conductive balls, then electrical connection reliability improves, but the process complexity increases
Solution Approach 1:
By applying the release agent beforehand, the removal of excess conductive material becomes a simple mechanical process rather than a complex selective removal operation. The release agent has already done the work of preventing adhesion, so the removal step is straightforward and does not add significant process complexity.
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 optimization significantly increases the manufacturing yield of touch panels by ensuring reliable electrical connections between the electrode-side and circuit-side terminal portions, enhancing the probability of contact and reducing contact resistance.
Implementation Method 1
the conductive ball physically comes into contact with the conductive material in the groove
Implementation Method 2
a resin material that is interposed between the substrate and the circuit board and includes a conductive ball electrically connecting the electrode-side terminal portions and the circuit-side terminal portions
Data Source
AI summary
A touch panel 10 includes a first electrode-side terminal portion 42A that is electrically connected to an upper detection electrode 36A. The first electrode-side terminal portion 42A includes a first resin layer 44a which is provided on a first substrate 34A and in which a first terminal groove 54a is formed and a first conductive material 48a which fills the first terminal groove 54a. A flexible print substrate 28 which is a circuit board is stacked on the first electrode-side terminal portion 42A through an anisotropic conductive film 60 including a conductive ball 61. A film including the conductive ball 61, of which the average diameter x has a predetermined relationship with the dimensions a of the first terminal groove 54a in a width direction and the depth c of a space 64 formed in the first terminal groove 54a, is selected as the anisotropic conductive film 60.