Touch Pad Bonding Reliability via Layer Segmentation
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Solution Overview
Problem
Existing touch pad manufacturing methods face challenges in ensuring strong adhesion between bonding pads due to differences in expansion coefficients of materials, leading to detachment issues and reduced product pass rates.
Innovation Solution
A touch pad design featuring a single layer of bonding pads in the second conductive pattern layer, with a first conductive pattern layer more proximate to the base and using different materials for the conductive pattern layers to prevent etching, along with a specific layer structure and connection pads to enhance bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers of bonding pads are stacked to ensure bonding, then bonding reliability is improved, but adhesion between layers deteriorates due to material expansion coefficient differences
Solution Approach 1:
The patent divides the bonding pad structure into two separate single-layer bonding pads located in different conductive pattern layers (first bonding pad in first conductive pattern layer, second bonding pad in second conductive pattern layer), eliminating the need for stacked multi-layer bonding pads and avoiding adhesion issues between stacked layers
Solution Approach 2:
The patent transitions from a vertical stacking approach (multiple layers stacked in the thickness direction) to a lateral distribution approach (bonding pads distributed across different conductive pattern layers in the plane), resolving the adhesion problem by eliminating direct vertical contact between bonding pad layers
2Ease of manufacture
If the first conductive pattern layer uses the same material as the second conductive pattern layer, then manufacturing is simplified, but etching damage occurs to the bonding pads
Solution Approach 1:
The patent applies different material properties to different conductive pattern layers: the first conductive pattern layer uses a material resistant to etching by the etchant used for the second layer (e.g., aluminum or aluminum alloy), while the second conductive pattern layer uses a different material (e.g., molybdenum, tungsten, or copper) that requires a different etchant, thereby protecting the first layer's bonding pads from etching damage
Solution Approach 2:
The patent introduces an insulating layer between the first and second conductive pattern layers, which also serves as an etching barrier, preventing the etchant used for the second layer from reaching and damaging the first layer's bonding pads
Data Source
AI summary
A touch pad includes a first conductive pattern layer, a second conductive pattern layer, a first trace, a second trace, a first bonding pad, and a second bonding pad. The first conductive pattern layer includes a first touch electrode extending in a first direction. The second conductive pattern layer includes a second touch electrode extending in a second direction. A first end of the first trace is coupled to the first touch electrode, and a second end of the first trace is coupled to the first bonding pad. A first end of the second trace is coupled to the second touch electrode, and a second end of the second trace is coupled to the second bonding pad. The first direction intersects the second direction.