Flexible Array Substrate Stress Cushion Layer for Narrow Border Displays
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Solution Overview
Problem
Conventional flexible array substrates face challenges in achieving a stress-neutral state for source/drain electrode wiring due to significant differences in Young's modulus between materials, leading to stress imbalance during pad bending, which complicates the design of narrow border display devices.
Innovation Solution
Incorporating a stress cushion layer with a Young's modulus ranging from 50 to 200 GPa, disposed over or between the organic photoresist and photosensitive adhesive layers, to balance stress at the pad bending area, featuring a stepped through-hole structure and varying thickness to accommodate the source/drain electrode wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the thickness of photosensitive adhesive layer or organic photoresist layer is increased to balance stress, then stress balance is improved, but the width of bottom border increases after bending
Solution Approach 1:
The stress cushion layer is selectively disposed only in the pad area above the source/drain electrode wiring, not throughout the entire substrate. This localized approach balances stress where needed while avoiding additional border width increase. The layer has different Young's modulus (50-200 GPa) compared to surrounding layers, providing targeted stress management.
Solution Approach 2:
The stress cushion layer is divided into multiple discrete layers including inorganic cushioning layers and organic cushioning layers, which can be independently controlled in thickness and material properties. This segmentation allows precise stress adjustment without uniformly increasing overall film thickness across the entire substrate.
2Stress or pressure
If the thickness of film layers is increased to balance stress, then stress adjustment effect is improved, but the available space is limited due to association with active area layers
Solution Approach 1:
The stress cushion layer is segmented into multiple thin layers (inorganic and organic cushioning layers) distributed vertically above the source/drain electrode wiring. This allows cumulative stress adjustment effect while maintaining each individual layer within available space constraints.
Solution Approach 2:
The stress cushion layer utilizes the vertical dimension (Z-axis) above the source/drain electrode wiring to provide stress balancing, rather than expanding horizontally. This allows stress adjustment without consuming lateral space that would be needed for border reduction.
3Stress or pressure
If a stress cushion layer with high Young's modulus is added, then stress balance is improved, but the device structure becomes more complex
Solution Approach 1:
The stress cushion layer is localized only in the pad area above source/drain electrode wiring where stress imbalance occurs during bending, not throughout the entire display area. This reduces overall structural complexity while providing targeted stress management where needed.
Solution Approach 2:
The stress cushion layer acts as an intermediary element between the substrate and the photosensitive adhesive/organic photoresist layers. It mediates stress distribution without requiring fundamental redesign of existing layers, integrating smoothly into the existing multi-layer structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The stress cushion layer effectively balances stress between layers, allowing for flexible array substrates to be bent without increasing film thickness, thus enabling the creation of display devices with narrow borders.
Implementation Method 1
the stress cushion layer is disposed over the source/drain electrode wiring, wherein the stress cushion layer is disposed in the organic photoresist layer, in the photosensitive adhesive layer, or between the organic photoresist layer and the photosensitive adhesive layer
Data Source
AI summary
A flexible array substrate and a display are disclosed. The flexible array substrate includes a substrate, an insulation layer disposed on the substrate and having a stepped through-hole, an organic photoresist body disposed in the stepped through-hole of the insulation on the substrate, a source/drain electrode wiring disposed over the organic photoresist body, an organic photoresist layer disposed over the source/drain electrode wiring, a photosensitive adhesive layer disposed over the organic photoresist layer, and a stress cushion layer disposed over the source/drain electrode wiring.