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
Engineering 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 causing reliability deterioration
Solution Approach 1:
The inorganic insulating layer is divided into multiple regions: a first inorganic insulating layer covering the transistor active region, and a second inorganic insulating layer covering the wiring region. This segmentation allows each layer to be optimized independently - the first layer maintains integrity for reliability while the second layer can accommodate bending stresses through openings.
Solution Approach 2:
Different regions of the inorganic insulating structure are given different properties. The first inorganic insulating layer is made continuous over the transistor region for reliability, while the second inorganic insulating layer has openings over the wiring region to reduce stress during bending, creating local quality differences that resolve the contradiction.
2Reliability
If the inorganic insulating layer is made continuous to prevent cracking, then reliability is improved, but moisture permeability increases causing deterioration of display elements
Solution Approach 1:
The insulating structure is segmented into inorganic and organic components arranged in specific patterns. The inorganic insulating layers provide moisture barrier functionality in critical areas, while organic insulating layers fill openings in non-critical areas, creating a segmented structure that simultaneously addresses both reliability and moisture protection.
Solution Approach 2:
The patent uses a composite structure combining inorganic insulating layers (for moisture barrier and reliability) with organic insulating layers (for stress relaxation and filling). This composite material approach allows the system to achieve both moisture protection and flexibility by leveraging the complementary properties of different materials in different locations.
Data Source
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.