Flexible Display Base Layer Silane Adhesion
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Solution Overview
Problem
Conventional flexible organic EL display devices experience film peeling issues during manufacturing due to poor adhesion between inorganic films and second resin layers, leading to reduced yield.
Innovation Solution
A method and configuration where a base layer is formed on a non-flexible substrate with a first resin layer, an inorganic film, and a second resin layer layered in order, with the second resin layer being in contact with the substrate or first resin layer at the end portion, and a flexible substrate is bonded via an adhesive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic film is formed by CVD between two polyimide resin layers to prevent infiltration of water and oxygen, then the barrier performance against foreign matter is improved, but the adhesion between the inorganic film and the second resin layer deteriorates, causing film peeling during washing steps
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the inorganic film and the second polyimide resin layer. The silane coupling agent contains both inorganic components (silicon-based) that bond with the inorganic film and organic components that bond with the polyimide resin, thereby improving adhesion between the two layers without compromising the barrier performance of the inorganic film
Solution Approach 2:
The patent creates a composite structure by incorporating silane coupling agent into the second polyimide resin layer. This composite material combines the properties of the polyimide resin (flexibility, barrier properties) with the adhesion-promoting properties of the silane coupling agent, resulting in a layer that adheres well to both the inorganic film and provides continuous barrier protection
2Reliability
If the inorganic film is formed covering the entire surface including end portions, then the barrier performance is improved, but the adhesion at the end portions deteriorates, causing peeling to progress from end portions inward during washing steps
Solution Approach 1:
The silane coupling agent is applied specifically at the end portions and regions where peeling is likely to occur, rather than uniformly across the entire surface. This localized treatment strengthens the adhesion at the most vulnerable areas without requiring changes to the overall structure, preventing peeling from initiating at the end portions
3Reliability
If a conventional base layer structure with inorganic film between resin layers is used, then the barrier performance against water and oxygen is improved, but film peeling occurs during washing steps reducing manufacturing yield
Solution Approach 1:
The silane coupling agent is applied in advance during the manufacturing process, before the washing steps that cause peeling. This preliminary treatment ensures that the adhesion problem is prevented before it occurs, allowing the device to withstand subsequent washing steps without film peeling, thereby maintaining high manufacturing yield
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
This configuration enhances the resistance to film peeling during manufacturing, resulting in a flexible display device with higher yield and improved reliability.
Implementation Method 1
an inorganic film formed by Chemical Vapour Deposition (CVD) or the like such as, for example, silicon oxide, silicon nitride, and silicon oxynitride
Data Source
AI summary
In a non-flexible substrate (10) including a base layer (2), the base layer (2) includes a portion where a first resin layer (2a), an inorganic film (2b′), and a second resin layer (2c) are layered in this order, and at an end portion of the base layer (2), the second resin layer (2c) is formed in contact with a glass substrate (1).