Touch Sensor Pad Unit Crack Prevention via Insulating Film Holes
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Solution Overview
Problem
Touch sensors face issues with crack prevention and contact resistance in the pad unit, which affects their reliability and performance.
Innovation Solution
The touch sensor design includes a substrate with a sensing area and a non-sensing area, featuring a touch input unit with intersecting sensing electrodes and a pad unit with conductive films and insulating films having holes of varying sizes and shapes, which helps in preventing cracks and optimizing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pad unit uses a conventional structure with uniform holes in the insulating film, then the manufacturing process is simple, but cracks occur in the pad unit and contact resistance increases
Solution Approach 1:
The insulating film is configured with different hole sizes in different regions: first holes with a first size in a first region, and second holes with a second size in a second region. This local differentiation allows the pad unit to prevent cracks while maintaining manageable complexity through targeted structural variation rather than uniform design throughout.
2Reliability
If the pad unit uses a conventional structure with uniform holes in the insulating film, then the device structure is simple, but contact resistance increases
Solution Approach 1:
Different hole sizes are implemented in different regions of the insulating film to optimize electrical contact properties. The first holes and second holes with different sizes create varied contact resistance characteristics in different pad regions, improving overall contact performance while maintaining reasonable structural complexity.
Solution Approach 2:
The hole size parameter in the insulating film is varied across different regions rather than maintaining a uniform value. This parameter change allows optimization of contact resistance by adjusting the effective contact area between conductive layers in different pad regions.
3Reliability
If holes of different sizes are introduced in the insulating film, then crack prevention and contact resistance improve, but the manufacturing precision requirements increase
Solution Approach 1:
The differentiation of hole sizes is implemented in a systematic manner with first holes in a first region and second holes in a second region. This localized approach allows manufacturing processes to focus on controlling specific hole size ranges in specific regions, making the precision requirements more manageable compared to requiring uniform precision across all holes.
Data Source
AI summary
A touch sensor includes a substrate, a touch input unit, a plurality of wires, and a pad unit. The touch input unit is disposed on the substrate and includes a plurality of sensing electrodes for sensing user touch. The pad unit includes a plurality of pads electrically connected to the sensing electrodes through the wires. The pads include a first pad. The first pad includes a first conductive film disposed on the substrate, an insulating film disposed on the first conductive film, and a second conductive film disposed on the insulating film. The insulating film includes a plurality of first-type holes and a plurality of second-type holes. Each first-type hole of the first-type holes is smaller than each second-type hole of the second-type holes.