Flexible Display Insulating Layer Cracking Prevention

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Solution Overview

Problem

Flexible display devices with inorganic insulating layers face reliability issues due to cracking when bent, and existing solutions that remove insulating films to prevent cracking compromise moisture barrier properties, leading to deterioration of thin-film transistors and display elements.

Innovation Solution

A display device configuration with an inorganic insulating layer having openings that expose wiring surfaces, filled with an organic insulating layer, which acts as a stress relaxation region to prevent cracking while maintaining moisture barrier functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the flexible substrate is bent, then the flexibility and portability of the display device are improved, but the inorganic insulating layer cracks and reliability deteriorates

Engineering Contradiction:

ImproveflexibilityVSAvoidinsulating layer integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The inorganic insulating layer is divided into multiple regions: continuous insulating regions over pixel regions and transistor regions, and discontinuous insulating regions over wiring regions. This segmentation allows the wiring regions to flex during bending while maintaining insulating coverage where needed, preventing cracks in critical areas.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different structural configurations are applied to different regions of the display device. The inorganic insulating layer is made continuous over pixel and transistor regions for reliability, while discontinuous over wiring regions for flexibility. This local differentiation resolves the contradiction between overall flexibility and local integrity.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the inorganic insulating layer is made discontinuous to prevent cracking, then flexibility is improved, but moisture barrier properties deteriorate

Engineering Contradiction:

Improvebending capabilityVSAvoidmoisture permeability

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent combines inorganic insulating layers with organic insulating layers to form a composite insulating structure. The inorganic layer provides moisture barrier properties while the organic layer provides flexibility. This merging allows the structure to bend without cracking the inorganic layer while maintaining moisture barrier functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

A composite insulating structure is formed by stacking inorganic and organic insulating layers. The inorganic insulating layer (e.g., silicon oxide, silicon nitride) provides excellent moisture barrier properties, while the organic insulating layer (e.g., polyimide) provides flexibility and crack resistance. This composite approach resolves the contradiction between moisture barrier and flexibility.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS10374023B2Flexible display device

Publication Date: 2019.08.06 MAGNOLIA WHITE CORP

AI summary

A display device includes: a flexible substrate; a pixel over the flexible substrate, the pixel including a transistor and a display element; a first wiring for transmitting a signal to the pixel, the first wiring extending in a first direction; a second wiring extending in a second direction intersecting the first direction; an inorganic insulating layer on a higher level than the first wiring or the second wiring; and an organic insulating layer on a higher level than the inorganic insulating layer, wherein the inorganic insulating layer has an opening exposing a part of the upper surface of the first wiring or the second wiring is exposed, and the organic insulating layer is provided in such a way as to fill the opening.