Display Panel Pad Alignment Mark Layout for Precise Film Bonding
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Solution Overview
Problem
Existing display devices face challenges in achieving precise alignment between the circuit film and the display panel, leading to reduced reliability due to position tolerance issues in the alignment process.
Innovation Solution
The alignment mark is disposed in the same layer as the pad pattern, allowing simultaneous formation with the pad pattern, thereby reducing alignment tolerance and improving the accuracy of the circuit film and display panel connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the alignment mark is disposed in a different layer from the pad pattern, then the alignment process is simpler, but the alignment accuracy between the circuit film and display panel deteriorates due to position tolerance accumulation
Solution Approach 1:
The alignment mark is merged with the pad pattern by disposing them in the same layer. This combining approach eliminates the need for separate alignment mark formation processes while ensuring that both the alignment mark and pad pattern share the same position tolerance reference, thereby improving alignment accuracy without significantly increasing process complexity
2Manufacturing precision
If the alignment mark is disposed close to the pad group, then the alignment accuracy improves, but the alignment mark becomes vulnerable to damage during the bonding process
Solution Approach 1:
The protective layer is selectively disposed to cover the alignment mark while leaving the pad group exposed through openings. This local protection approach ensures that the alignment mark is protected from damage during bonding and subsequent processes, while the pad group remains accessible for electrical connection, thus maintaining both alignment accuracy and alignment mark integrity
3Strength
If the protective layer covers both the pad group and alignment mark with openings for pads, then the pad patterns are protected, but the alignment mark may be exposed to damage
Solution Approach 1:
The protective layer is configured with different coverage characteristics for different regions: it covers the alignment mark to protect it from damage, while providing openings that expose the pad group for electrical connection. This differentiated protection strategy ensures both the alignment mark and pad patterns are appropriately protected or exposed based on their functional requirements
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.