Display Panel Passive Covering Layer Thickness Variation
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Solution Overview
Problem
The Chip-On-Glass packing technique for display panels faces challenges with shifting errors during manufacturing, leading to potential short-circuiting of metal signal traces due to conductive particles penetrating the isolation structure, which limits the tolerance range and can result in beaded drainage between signal pads.
Innovation Solution
A passive covering layer with varying thicknesses is introduced, extending from the display area to the non-display area, featuring protruding or concave structures to prevent conductive particles from penetrating the isolation structure and forming beaded drainage, thereby enhancing the anti-penetration effect and allowing a wider tolerance range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the Chip-On-Glass packing technique is used to reduce display panel thickness, then the overall profile is reduced, but the tolerance range for manufacturing shifts becomes extremely limited due to the risk of conductive particles short-circuiting metal signal traces
Solution Approach 1:
A passive covering layer is formed over the metal signal traces in the non-display area before the bonding process. This covering layer is prepared in advance to prevent conductive particles from short-circuiting the traces during subsequent manufacturing steps, thereby enabling greater tolerance for manufacturing shifts while maintaining the thin profile achieved through Chip-On-Glass packing
Solution Approach 2:
The passive covering layer acts as an intermediary barrier between the metal signal traces and conductive particles. This intermediate structure prevents direct contact between conductive particles and the traces, resolving the contradiction by allowing thicker bonding layers without short-circuit risks, thus expanding the manufacturing tolerance range
2Manufacturing precision
If the tolerance range is expanded to accommodate manufacturing shifts, then manufacturing errors are reduced, but conductive particles may penetrate the isolation structure and short-circuit metal signal traces
Solution Approach 1:
The passive covering layer is implemented as a preventive cushioning measure before the bonding process. This layer provides a safety buffer that absorbs manufacturing variations and prevents conductive particles from reaching the metal signal traces, thereby maintaining reliability even when the tolerance range is expanded to accommodate manufacturing shifts
3Manufacturing precision
If a passive covering layer is extended to the non-display area to prevent short-circuiting, then manufacturing tolerance is improved, but the device complexity increases
Solution Approach 1:
The passive covering layer is selectively extended only to the non-display area where metal signal traces are located, rather than covering the entire display panel. This localized approach provides the necessary protection and manufacturing tolerance improvement while minimizing the increase in device complexity by avoiding unnecessary coverage in the display area
Data Source
AI summary
A display panel includes a display area, a non-display area, a plurality of signal pads and a passive covering layer. The non-display area is adjacent to the display area. The signal pads are disposed within the non-display area. The passive covering layer is disposed on the display area and extends to cover at least a portion of the non-display area. The passive covering layer has a first thickness within the display area. The passive covering layer has a second thickness within the non-display area. The first thickness is greater than the second thickness.