Display Panel Pad Structure With Same-Layer Alignment Mark
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Solution Overview
Problem
Existing display devices face challenges in achieving accurate alignment between the circuit film and the display panel, leading to reduced reliability due to position tolerance issues in the alignment mark and pad patterns.
Innovation Solution
The alignment mark is disposed in the same layer as the pad pattern, allowing both to be formed through the same process, thereby reducing the impact of position tolerance and improving alignment accuracy between the circuit film and the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the alignment mark and pad pattern are formed in different layers, then the alignment process becomes more flexible, but the alignment accuracy deteriorates due to position tolerance accumulation
Solution Approach 1:
The alignment mark and pad pattern are merged into the same layer (the second conductive layer), eliminating the need for cross-layer alignment. This resolves the technical contradiction by forming both features simultaneously through the same patterning process, thereby achieving high alignment accuracy without increasing device complexity.
2Reliability
If the alignment mark is spaced close to the pad group, then the alignment process is simplified, but the electrical connection reliability deteriorates due to potential interference
Solution Approach 1:
The alignment mark is positioned in a specific location (the pad area but spaced from the pad group) where it can perform its alignment function without interfering with electrical connections. This local optimization resolves the contradiction by maintaining electrical reliability while preserving alignment simplicity.
3Reliability
If multiple pad patterns are stacked vertically, then the electrical connection capability is improved, but the alignment precision deteriorates due to cumulative position tolerance
Solution Approach 1:
The alignment mark is placed in the same layer as the uppermost pad pattern (second pad pattern), allowing them to be formed in the same patterning step. This eliminates cumulative position tolerance from multi-layer alignment while maintaining the vertical stacking of pad patterns for improved electrical connection capability.
Data Source
AI summary
A display device includes a display panel including a display area and a pad area. The display panel includes a base substrate, a pixel, a pad group, an alignment mark, and a protective layer. The pad group includes a plurality of pads arranged in a first direction. The alignment mark is spaced apart from the pad group in the first direction. The protective layer covers the pads and the alignment mark and a plurality of openings respectively exposing upper surfaces of the pads is defined in the protective layer. Each of the pads includes at least one pad pattern, and the alignment mark is disposed in a same layer as a pad pattern spaced farthest from the base substrate among the at least one pad pattern.