Flat Source-Drain Electrode Surface for Flexible Touch Display Yield
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Solution Overview
Problem
In Flexible Multiple Layer On Cell (FMLOC) display panels, the touch electrode line is prone to breaking when bent, leading to reduced yield and functionality of touch display products due to the non-flat surface of the source-drain electrode layer under the passivation layer, which causes damage during etching and bending.
Innovation Solution
A display panel design with a flat surface of the second source-drain electrode layer exposed through a large-sized through hole in the dielectric layer, and additional through holes in the passivation and planarization layers to ensure a flat and protected surface for the touch electrode line connection, reducing the risk of damage and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source-drain electrode layer has a non-flat surface under the passivation layer, then the touch electrode line connection is achieved, but the touch electrode line is easily broken when the wiring is bent
Solution Approach 1:
The patent applies preliminary action by creating a flat surface on the source-drain electrode layer before subsequent processing steps. The method involves removing excess electrode material to form a flat surface, and then forming a protective layer over this flat surface. This preliminary flatening prevents bending-induced breakage of the touch electrode line during later wiring processes.
Solution Approach 2:
The patent implements beforehand cushioning by introducing a protective layer (dielectric layer with through-hole) that covers and protects the source-drain electrode layer. This protective structure cushions the electrode line from mechanical stress during bending, preventing breakage while maintaining electrical connectivity.
2Productivity
If the touch electrode line is connected through the source-drain electrode layer in the peripheral area, then the solder pad area can be positioned on the back, but the touch electrode line is easily damaged during etching and bending
Solution Approach 1:
The patent applies beforehand cushioning by forming a protective dielectric layer with a through-hole that covers the source-drain electrode layer. This protective structure is established before the touch electrode line is routed through the peripheral area, cushioning the electrode line from etching damage and bending stress, thereby improving production yield.
Solution Approach 2:
The patent uses an intermediary protective layer (dielectric material) that mediates between the touch electrode line and harmful external factors such as etching chemicals and mechanical bending forces. This intermediary layer protects the electrode line while allowing electrical connectivity through the through-hole.
3Manufacturing precision
If the surface of the source-drain electrode layer is made flat by removing excess material, then the touch electrode line connection is improved, but additional manufacturing steps are required
Solution Approach 1:
The patent merges the flatening operation with the existing source-drain electrode layer formation process. The flat surface is created during the same manufacturing stage as the electrode layer deposition, combining multiple functions into a single process step. This reduces overall manufacturing complexity while achieving the required surface precision.
Data Source
AI summary
A display panel includes: an active area; a peripheral area; a solder pad area at a side of the peripheral area away from the active area; a first source-drain electrode layer, a passivation layer and a second source-drain electrode layer and a dielectric layer stacked on a back plate in the peripheral area; a touch electrode in the active area; a touch electrode line connected to the touch electrode. The touch electrode line extends from the active area to the peripheral area, and is connected to the solder pad area through the second source-drain electrode layer in the peripheral area. The touch electrode line is connected to the second source-drain electrode layer through a first through hole in the dielectric layer. A portion of a surface of the second source-drain electrode layer, which is away from the passivation layer and exposed through the first through hole, is a flat surface.