Adhesion-Enhancing Layer for Flexible Display Substrates
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Solution Overview
Problem
Flexible display substrates face issues with film layer separation and cracking in bending areas, leading to signal trace breakage and poor display performance during reliability tests, especially under high temperature and humidity conditions.
Innovation Solution
A display substrate design that includes adhesion-enhancing layers between the trace layer and insulating layers, with overlapping areas within the bending region, using materials like acrylic resin, epoxy resin, or polyimide, to enhance adhesion and reduce stress on the signal traces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible base substrate with bending area is used to enable flexible display, then adaptability and versatility are improved, but film layer separation and cracking occur in the bending area leading to reduced reliability
Solution Approach 1:
An adhesion-enhancing layer is introduced as an intermediary between the trace layer and the first insulating layer. This intermediate layer specifically addresses the film layer separation problem in the bending area by providing enhanced bonding strength, allowing the flexible substrate to bend without causing delamination of the trace layer and insulating layer.
Solution Approach 2:
The adhesion-enhancing layer is formed using a composite material structure with specific material composition (acrylic resin, epoxy resin, or polyimide) and controlled thickness (1-3 microns). This composite approach combines the flexibility needed for bending with the adhesion strength required to prevent film layer separation, resolving the contradiction between flexibility and reliability.
2Ease of operation
If the display substrate is made flexible to enable bending, then ease of operation is improved, but stress concentration causes signal trace breakage reducing reliability
Solution Approach 1:
The thickness of the adhesion-enhancing layer is precisely controlled within the range of 1-3 microns. This parameter optimization balances the mechanical properties: thin enough to maintain flexibility and allow bending, but thick enough to provide sufficient adhesion strength and stress distribution to prevent signal trace breakage in the bending area.
3Reliability
If adhesion-enhancing layer is added to improve film layer adhesion, then reliability is improved, but device complexity increases
Solution Approach 1:
The adhesion-enhancing layer is selectively applied in the bending area where film layer separation is most likely to occur. By concentrating the adhesion enhancement only where needed rather than uniformly across the entire substrate, the solution improves reliability in the critical bending region while minimizing the increase in overall device complexity.
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 solution effectively reduces the likelihood of signal trace breakage and improves the reliability of flexible display substrates by enhancing adhesion and balancing stress across film layers, thereby enhancing display performance and durability.
Implementation Method 1
the first adhesion-enhancing layer is bonded to the first insulating layer and the trace layer respectively
Implementation Method 2
a material of the first adhesion-enhancing layer includes one or more of an acrylic resin, an epoxy resin, and a polyimide
Data Source
AI summary
The display substrate includes: the flexible base substrate and the trace layer, a first adhesion-enhancing layer, and a first insulating layer that are stacked on the flexible base substrate, wherein the first adhesion-enhancing layer is between the first insulating layer and the trace layer, and the first adhesion-enhancing layer is bonded to the first insulating layer and the trace layer respectively. The flexible base substrate is provided with a bending area, and an overlapping area is present between an area which an orthographic projection of the first adhesion-enhancing layer on the flexible base substrate is within and the bending area, and an orthographic projection of the signal trace in the trace layer on the flexible base substrate falls in the bending area.