Array Substrate Signal Line Stacking for Minimal-Pitch Fanout
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Solution Overview
Problem
Existing flexible display apparatuses face challenges in patterning a high number of signal lines in limited areas such as the fanout and bending areas while maintaining a minimal pitch, particularly in high-resolution arrays with complex pixel arrangements like Real RGB, leading to fabrication issues and potential cross-talk between signal lines.
Innovation Solution
The array substrate design incorporates signal lines in multiple layers, with portions of signal lines in different layers partially stacked and insulated by insulating layers, and uses multiplexers to reduce the number of signal lines, allowing for minimal pitch maintenance and reducing cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If signal lines are patterned in a single layer with minimal pitch in high-resolution arrays, then the number of signal lines can be increased, but fabrication issues and cross-talk between signal lines occur
Solution Approach 1:
The patent transitions from a single-layer signal line configuration to a multi-layer configuration. Signal lines are distributed across multiple layers (e.g., first metal layer, second metal layer, third metal layer) with vertical stacking. This dimensional change allows more signal lines to be accommodated without increasing the planar pitch, thereby preventing cross-talk while maintaining high signal line quantity.
Solution Approach 2:
The signal line network is segmented into multiple independent layers. Each layer contains a subset of signal lines that are electrically isolated from other layers by insulating structures. This segmentation allows each layer to be patterned and processed independently, improving fabrication reliability while increasing the total number of signal lines through vertical stacking.
2Area of stationary object
If signal lines are placed closer together to maintain minimal pitch, then area is saved, but cross-talk between adjacent signal lines increases
Solution Approach 1:
The patent resolves the cross-talk issue by moving signal lines from a two-dimensional planar arrangement to a three-dimensional multi-layer arrangement. Signal lines that would be adjacent in the planar view are separated vertically into different layers, with insulating layers providing electrical isolation. This allows minimal pitch maintenance in the planar direction while eliminating cross-talk through vertical separation.
Solution Approach 2:
Insulating layers and interlayer dielectric structures are introduced as intermediary elements between adjacent signal lines in different layers. These intermediary structures provide electrical isolation and prevent cross-talk while allowing the signal lines to maintain minimal pitch in the planar direction. The insulating materials act as mediators that enable close spacing without harmful electromagnetic coupling.
3Quantity of substance
If more signal lines are patterned in limited areas like fanout and bending areas, then connection density is increased, but fabrication precision requirements become more stringent
Solution Approach 1:
The high-density signal line region is segmented into multiple fabrication layers, each containing a manageable subset of signal lines. This segmentation reduces the patterning density requirement for each individual layer, making fabrication more feasible. Each layer can be processed with standard precision requirements while the overall connection density is achieved through vertical stacking of multiple layers.
Solution Approach 2:
The patent distributes signal lines across multiple vertical layers to reduce the horizontal patterning density. Instead of fitting all signal lines in a single planar layer with extremely tight pitch, the same number of signal lines are distributed across multiple layers with relaxed pitch requirements. This dimensional distribution significantly reduces manufacturing precision requirements while maintaining high connection density.
4Object-generated harmful factors
If signal lines are arranged in multiple layers with stacking, then cross-talk is reduced, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the multi-layer structure: signal transmission, electrical isolation, and mechanical support are all integrated into the layered architecture. The same structural elements that provide mechanical support and insulation also enable the vertical stacking of signal lines. This merging reduces the need for additional separate components and processes, offsetting the apparent complexity with functional integration.
Solution Approach 2:
The multi-layer structure serves multiple purposes simultaneously: it provides electrical isolation between signal lines (reducing cross-talk), provides mechanical support for the flexible display, enables routing of different signal types, and allows for minimal pitch maintenance. Each layer is designed to be multi-functional, reducing the need for separate dedicated structures and thereby managing overall device complexity despite the increased layer count.
Data Source
AI summary
An array substrate is provided, comprising a plurality of signal lines; wherein a respective signal line of the plurality of signal lines comprises a first portion in a first area and a second portion in a second area, the first portion and the second portion being in different layers; second portions of the plurality of signal lines are grouped into a plurality of pairs, a respective pair comprising a first-second portion and a second-second portion of two adjacent signal lines of the plurality of signal lines; and an orthographic projection of the first-second portion on a base substrate and an orthographic projection of the second-second portion on the base substrate at least partially overlap with each other.