Display Test Line Layout to Resist Liquid-Induced Shorts
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Solution Overview
Problem
During the manufacturing of display devices, such as LCDs and OLEDs, the test line region is prone to defects like shorts or burnt portions due to liquid penetration, which can occur when the display device is exposed to cleaning liquids or environmental moisture, leading to potential image quality issues.
Innovation Solution
The display device incorporates a unique arrangement of test lines with varying intervals and orientations, where the test lines are inclined and bent, forming groups that converge towards the center, with a flexible printed circuit board overlapping the pad region but not the test line region, and an anisotropic conductive layer ensuring electrical connectivity without sealing the test line region, thereby minimizing exposure to liquids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If test lines are arranged in a regular grid pattern in the test line region, then manufacturing is simple and easy, but liquid penetration causes shorts and burnt portions leading to defects
Solution Approach 1:
The patent applies asymmetry by arranging test lines with non-uniform intervals and varying orientations. Test lines are inclined at different angles and positioned asymmetrically relative to the pad region and display area, creating an irregular pattern that prevents liquid accumulation pathways while maintaining manufacturing feasibility through systematic design rules.
Solution Approach 2:
The patent implements curvature by bending test lines in multiple directions rather than using straight lines. Test lines include curved sections that change direction, creating a meandering path that reduces liquid penetration risk. The curved geometry disrupts straight liquid flow paths while maintaining electrical connectivity for testing.
2Manufacturing precision
If test lines are arranged with uniform intervals, then manufacturing precision is easier to control, but liquid can easily penetrate and cause defects
Solution Approach 1:
The patent applies local quality by varying test line intervals based on location. Test lines closer to the pad region have different spacing compared to those near the display area edge. This non-uniform spacing creates regions with different liquid resistance characteristics, preventing uniform liquid penetration while maintaining controllable manufacturing tolerances through localized design parameters.
3Reliability
If the flexible printed circuit board covers the test line region, then electrical connectivity is ensured, but liquid exposure to test lines increases causing defects
Solution Approach 1:
The patent extracts the test line region from the area covered by the flexible printed circuit board. By positioning test lines in a region not overlapped by the FPCB, the design separates the electrical connectivity function (handled by FPCB over pad region) from the testing function (handled by exposed test lines). This extraction reduces liquid exposure risk while maintaining necessary electrical connections through alternative routing.
Data Source
AI summary
A display device includes a substrate, pixels on the substrate, pads, and test lines. The pads are between the pixels and an edge of the substrate and include a first pad and a second pad. The test lines include a first test line and a second test line. The first test line includes a first section and a second section. The second section is closer to the edge of the substrate than the first section and is connected through the first section to the first pad. The second test line includes a first segment and a second segment. The second segment is closer to the edge of the substrate than the first segment and is connected through the first segment to the second pad. A minimum distance between the first section and the first segment is larger than a minimum distance between the second section and the second segment.