Touch Sensor Bezel Recess for Bonding Reliability
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Solution Overview
Problem
The reduction of bezel area in touch sensors complicates the bonding process between bonding pads and electrode pads, leading to increased connection failure rates and product defects, making it difficult to further narrow the bezel area.
Innovation Solution
A touch sensor design featuring a base layer with recessed portions outside the electrode pad, allowing for a wider bonding area and the use of a conductive film and through holes to facilitate bonding with a printed circuit board, while removing excess base layer material post-bonding to achieve a narrow bezel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the bezel area is reduced to widen the display area, then the display area is increased, but the bonding process between bonding pad and electrode pad becomes difficult and connection failure rate increases
Solution Approach 1:
The invention forms a protrusion structure on the bonding pad before the actual bonding process. This preliminary structural preparation provides a larger bonding surface area and better mechanical interlocking, ensuring reliable bonding even when the overall electrode pad size is reduced due to narrower bezel requirements.
Solution Approach 2:
The invention creates a localized protrusion structure specifically at the bonding pad region, concentrating the bonding functionality in this local area. This allows the bonding pad to have enhanced bonding capability without increasing the overall size of the electrode pad, thus maintaining the reduced bezel width while ensuring bonding reliability.
2Area of moving object
If the bezel area is reduced, then the display area is widened, but the width of ACF is reduced leading to increased connection failure rate
Solution Approach 1:
The protrusion structure concentrates the bonding function in a specific localized region with enhanced surface area. This localized enhancement provides better alignment tolerance and bonding precision without requiring the entire ACF width to be increased, thus maintaining narrow bezel while improving bonding reliability.
3Length of stationary object
If the electrode pad size is reduced to match narrow bezel, then the bezel area is narrowed, but the bonding process becomes more difficult
Solution Approach 1:
The invention creates a localized protrusion structure on the bonding pad that provides enhanced bonding surface area. This allows the overall electrode pad to remain small (maintaining narrow bezel) while the local protrusion region provides sufficient bonding area to make the bonding process easy and reliable.
Solution Approach 2:
The protrusion structure is formed in advance on the bonding pad before the bonding process. This preliminary structural preparation ensures that when bonding occurs, there is already an optimized bonding surface geometry that facilitates easier and more reliable bonding, even with reduced electrode pad dimensions.
Data Source
AI summary
A touch sensor includes a base layer and an electrode pad portion formed in a bezel area of the base layer. The base layer includes recessed portions, which are spaced apart along the edge and recessed inward, outside the electrode pad portion.