Pad Connection Structure for High-Resolution Touch Sensors
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Solution Overview
Problem
High-resolution touch sensors face challenges in maintaining electrical connection reliability due to decreasing pad width and pitch, leading to increased electrical resistance and mechanical connection failures.
Innovation Solution
A pad connection structure is developed with a substrate, lower insulation layer, pad electrode, and upper insulation layer, where the lower insulation layer has inclined sidewalls and the pad electrode covers it, with an upper insulation layer forming a protrusion to reduce step height and enhance adhesion of conductive connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the width or pitch of the pad is decreased to achieve high resolution, then the resolution of the touch sensor is improved, but the electrical connection reliability is degraded and electrical connection resistance is increased
Solution Approach 1:
The pad electrode is extended in the vertical dimension by forming it on an inclined lower insulation layer, creating a stepped structure that increases the pad height. This dimensional extension allows the pad to maintain adequate electrical connection properties even when the horizontal width and pitch are reduced for high resolution requirements.
Solution Approach 2:
The lower insulation layer is formed with an inclined sidewall at a specific angle (30° to 60°), changing the geometric parameters of the pad structure. This inclination angle optimization allows the pad electrode to achieve both compact horizontal footprint and sufficient vertical height, resolving the contradiction between reduced pitch and maintained connection reliability.
2Measurement precision
If the width or pitch of the pad is decreased to achieve high resolution, then the resolution of the touch sensor is improved, but the mechanical connection failure risk is increased
Solution Approach 1:
By extending the pad electrode vertically through the inclined lower insulation layer structure, the mechanical connection interface is enhanced in the vertical dimension. This increased pad height provides greater structural integrity and resistance to mechanical failure, compensating for the reduced horizontal dimensions required for high resolution.
Solution Approach 2:
The structure combines the lower insulation layer with inclined sidewalls and the pad electrode forming a composite stepped structure. This composite design integrates mechanical support and electrical connection functions, enhancing overall connection strength while maintaining compact horizontal footprint for high resolution.
3Reliability
If the pad electrode height is increased to improve connection reliability, then the adhesion of conductive connection structure is enhanced, but the step height between upper insulation layer and pad electrode increases
Solution Approach 1:
The lower insulation layer is formed with a controlled inclination angle (30° to 60°) to optimize the pad electrode height. This parameter control ensures that the pad achieves sufficient vertical extension for reliable connection while the upper insulation layer is positioned to minimize the exposed step height, balancing adhesion enhancement with planarization requirements.
Data Source
AI summary
A pad connection structure includes a substrate, a lower insulation layer formed on a top surface of the substrate, a pad electrode disposed on the lower insulation layer, and an upper insulation layer including an opening through which a top surface of the pad electrode. A step height via the opening is reduced by the lower insulation layer so that connecting reliability with a conductive connection structure is improved.