Signal Pad Alignment Inspection Using Reference Polymer Patterns
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Solution Overview
Problem
Misalignment during the deposition of materials on signal pads in display devices leads to performance and reliability issues, especially as display device shapes become more complex, impacting the yield and functionality of these devices.
Innovation Solution
The introduction of an alignment pad and alignment polymer pattern, both formed in the same process step and strategically spaced apart from the main signal pad, allows for precise alignment inspection by comparing the centers of these features, enhancing alignment inspection quality and ensuring correct alignment of polymer patterns on signal pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If material is deposited on signal pads during manufacturing, then reliable electrical connections are achieved, but misalignment occurs leading to performance degradation and yield loss
Solution Approach 1:
An alignment pad is introduced as an intermediary element between the signal pad and the deposited material. The alignment pad includes alignment markers that serve as reference points for precise alignment during material deposition. This intermediary structure enables accurate positioning without directly involving the functional signal pad, thereby maintaining connection reliability while improving alignment precision.
Solution Approach 2:
The alignment pad creates a simplified copy or reference model of the signal pad structure, containing only the essential alignment markers needed for positioning. This copied structure allows for precise alignment inspection and material deposition without the complexity of the full signal pad structure, improving manufacturing precision while keeping the original signal pad intact for reliable electrical connections.
2Adaptability or versatility
If display device shape becomes more complex, then functionality is enhanced, but alignment and deposition processes become more challenging
Solution Approach 1:
The manufacturing process is segmented into two independent stages: first, forming the alignment pad with alignment markers; second, using these markers to guide material deposition on the signal pad. This segmentation allows the alignment reference to be established separately from the functional structure, making the process more manageable for complex device shapes and reducing overall manufacturing difficulty.
Solution Approach 2:
The alignment pad and alignment markers are formed in advance before the actual material deposition on the signal pad. This preliminary action establishes a ready-made alignment reference system that simplifies subsequent deposition processes, even for complex display device shapes, thereby reducing the difficulty of alignment operations.
3Device complexity
If alignment inspection is performed without dedicated alignment features, then manufacturing process is simpler, but alignment inspection quality is insufficient
Solution Approach 1:
Dedicated alignment markers on the alignment pad serve as intermediary reference features specifically for inspection purposes. These markers provide high-contrast, easily detectable features that enable precise alignment measurement without complicating the overall manufacturing process, as the markers are formed simultaneously with the alignment pad structure.
Solution Approach 2:
The alignment pad structure serves multiple functions: it provides mechanical support, defines the alignment reference, and enables inspection. By combining these functions into a single structure formed in the same process step as the signal pad, the solution maintains process simplicity while achieving high alignment inspection quality through the integrated alignment markers.
Data Source
AI summary
A display device includes a pixel, a signal line electrically connected to the pixel, a signal pad electrically connected to the signal line, an alignment pad spaced apart from the signal pad, and an alignment polymer pattern spaced apart from the alignment pad. The signal pad includes a first conductive pattern electrically connected to an end of the signal line, a conductive polymer pattern disposed on the first conductive pattern, and a second conductive pattern disposed on the conductive polymer pattern.