Flexible Substrate Fabrication with Stress-Absorbing Layer

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Solution Overview

Problem

The fabrication of flexible display panels is hindered by stresses generated between the flexible substrate material layer and the rigid substrate, leading to bending and cracking issues, which affect device precision and performance due to differences in Young's modulus and thermal expansion coefficients.

Innovation Solution

A stress-absorbing layer is formed on the back-surface of a bearing substrate, allowing a flexible substrate material layer, a blocking layer, and a device layer to be sequentially deposited on the bearing surface, with the bearing substrate and stress-absorbing layer subsequently removed to balance interface stresses and prevent cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a flexible substrate material layer is formed on a rigid substrate, then the flexible substrate can be fabricated, but stresses are generated due to different Young's modulus and thermal expansion coefficients, causing bending and cracking

Engineering Contradiction:

Improveflexible substrate fabricationVSAvoidsubstrate integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent divides the substrate structure into multiple functional layers: a rigid bearing substrate providing mechanical support, a flexible substrate material layer containing the device, and a stress-absorbing layer specifically designed to manage thermal and mechanical stresses. This segmentation allows each layer to perform its specialized function, preventing stress-induced cracking while enabling flexible substrate fabrication.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stress-absorbing layer acts as an intermediary between the rigid bearing substrate and the flexible substrate material layer. It mediates the stress transfer by absorbing thermal expansion differences and mechanical stresses, preventing direct stress transmission that would cause cracking in the flexible substrate while still allowing the structure to be manufactured.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If sequential layers are formed on the rigid substrate, then device functionality is achieved, but interface stresses cause bending and affect fabrication precision

Engineering Contradiction:

Improvedevice functionalityVSAvoidfabrication precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The device structure is segmented into distinct functional layers (flexible substrate material layer, blocking layer, device layer) formed on the bearing substrate, with the stress-absorbing layer providing structural support. This segmentation enables each layer to be optimized for its specific function while the bearing substrate maintains overall structural integrity and fabrication precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stress-absorbing layer serves as a mediator that decouples the thermal and mechanical stress effects from the functional device layers. By absorbing interface stresses between the bearing substrate and flexible substrate material layer, it prevents stress-induced bending that would compromise fabrication precision, while allowing the device layers to function as intended.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the bearing substrate is removed to obtain a flexible substrate, then flexibility is achieved, but stress balance is disrupted causing cracking

Engineering Contradiction:

Improvesubstrate flexibilityVSAvoidsubstrate integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The stress-absorbing layer is formed on the bearing substrate before the flexible substrate material layer is deposited. This preliminary action ensures that the stress-absorbing layer is already in place to manage stresses during subsequent processing and when the bearing substrate is removed, preventing cracking while achieving substrate flexibility.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The stress-absorbing layer acts as a permanent intermediary that remains attached to the flexible substrate material layer after the bearing substrate is removed. It continues to provide stress management and structural support, maintaining substrate integrity while allowing the substrate to achieve the necessary flexibility for its intended application.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10325941B2Flexible substrate and fabrication method thereof, and display panel

Publication Date: 2019.06.18 SHANGHAI TIANMA MICRO ELECTRONICS CO LTD

AI summary

A flexible substrate, a display panel, and a fabrication method of the flexible substrate are provided. The fabrication method comprises providing a bearing substrate including a bearing surface and a back-surface opposite to the bearing surface, and forming a stress-absorbing layer on the back-surface of the bearing substrate. The fabrication method further comprises forming a flexible substrate material layer, a blocking layer, and a device layer sequentially on the bearing surface of the bearing substrate, and removing the bearing substrate and the stress-absorbing layer formed on the back-surface of the bearing substrate.