On-Cell Touch Trace Layout to Prevent Dam-Induced Short Circuits
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Solution Overview
Problem
Flexible Multi-Layer On Cell (FMLOC) display panels suffer from short circuits between adjacent touch traces, leading to touch failure due to photoresist residue on dam structures during the manufacturing process.
Innovation Solution
The touch trace design includes alternately arranged sub-portions with varying widths and reduced widths at dam structure intersections to minimize photoresist accumulation, enhancing the spacing between traces and reducing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the touch trace width is increased to improve signal transmission, then the electrical performance is improved, but the spacing between adjacent traces decreases causing short circuits
Solution Approach 1:
The touch trace is designed with varying widths along its length, with narrower sections positioned where traces are closest to each other and wider sections where more spacing is available. This local variation in trace width optimizes the balance between electrical performance and spacing requirements at different locations along the trace path.
2Manufacturing precision
If the photoresist coating thickness is increased to ensure complete trace coverage, then the manufacturing coverage is improved, but the photoresist residue on dam structures increases causing short circuits
Solution Approach 1:
The trace geometry is pre-designed with wider spacing sections and narrower sections positioned strategically before the photoresist coating process. This preliminary geometric optimization ensures that even with standard photoresist thickness, adequate spacing is maintained between traces, preventing residue-induced short circuits while still achieving complete coverage.
3Object-affected harmful factors
If the spacing between adjacent touch traces is increased to prevent short circuits, then the short circuit risk is reduced, but the trace density and screen real estate utilization decreases
Solution Approach 1:
The touch trace is segmented into multiple sections with different widths along its path. Narrower segments are positioned in high-density areas where spacing is constrained, while wider segments are placed in areas with more available space. This segmentation allows the trace to adapt to local spacing constraints while maintaining overall trace density and screen utilization.
Data Source
AI summary
A display panel and a display device are disclosed. The display panel includes: a touch electrode, at least located in the display region; and a touch trace, electrically connected with the touch electrode, and disposed on a side of the dam structure away from the base substrate; where the touch trace includes a first trace portion, and an orthographic projection of at least a part of the first trace portion on the base substrate overlaps with an orthographic projection of the first dam portion on the base substrate; the first trace portion comprises at least one first trace sub-portion having an average width of a first width, and at least one second trace sub-portion having an average width of a second width, where the first width is less than the second width.