TFT Array Bridge Routing for Bend-Region Metal Line Breakage
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Solution Overview
Problem
In conventional flexible AMOLED display panels, the metal lines in the bending region are prone to breakage due to raised edges in the filling layer, leading to stress and short circuits during the etching process.
Innovation Solution
A novel segmented bridge routing structure for the first metal layer in the bending region, where the metal layer is divided into segments and connected by a bridging second metal layer, avoiding direct passage through holes in the filling layer and using a planarization layer to fill the original position, thereby preventing breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first metal layer is routed through holes in the filling layer in the bending region, then the metal line can be formed to connect source and drain, but the metal line is prone to breakage due to raised edges and stress concentration
Solution Approach 1:
The first metal layer is divided into two separate segments (first segment and second segment) that are disposed at intervals, avoiding the need for the metal layer to pass through the problematic filling layer holes. This segmentation eliminates the stress concentration point and prevents breakage while maintaining electrical connectivity through alternative routing.
Solution Approach 2:
An insulating layer is introduced as an intermediary between the first metal layer segments and the filling layer structure. This insulating layer provides a protective barrier and stress-distributing interface, preventing direct contact between the metal layer and the raised filling layer edges that cause breakage.
2Ease of manufacture
If the filling layer holes are positioned on both sides of the frame line region, then the filling layer structure is formed, but the middle portion becomes raised causing bending stress concentration
Solution Approach 1:
The insulating layer is selectively applied in the frame line region where the filling layer holes create raised portions. This localized modification addresses the stress concentration problem specifically in the problematic area without altering the overall filling layer structure or manufacturing process for the rest of the device.
Solution Approach 2:
The insulating layer is deposited beforehand to cushion and distribute the bending stress that will occur during device operation. This preventive measure compensates for the inherent stress concentration caused by the filling layer hole configuration before the stress actually occurs during bending.
Data Source
AI summary
A TFT array substrate includes a substrate layer and a metal layer disposed on the substrate layer. The metal layer includes a metal layer bridging structure having a first metal layer and a bridging second metal layer. An insulating layer is disposed between the first metal layer and the bridging second metal layer. The first metal layer includes two segments of a first segment and a second segment of the first metal layer, which are disposed at intervals. The first segment and the second segment of the first metal layer are connected by the bridging second metal layer. The TFT array substrate has a bending region adopting a new metal layer routing structure, and routing of the first metal layer in the bending region is prevented from passing through two holes of a filling layer (OILD), thereby effectively reducing the risk of subsequent breakage due to over-etching.