Polyimide Laminate Separation for Flexible Displays
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Solution Overview
Problem
The existing methods for fabricating flexible display devices require complex processes and increased costs due to the need for laser or light irradiation to separate flexible substrates from carrier substrates, which can lead to defects and reliability issues.
Innovation Solution
A laminate comprising a carrier substrate and polyimide resin layers with controlled thermal expansion coefficients and adhesive properties, allowing for easy separation of the flexible substrate without chemical changes or additional processing steps, such as laser or light irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser or light irradiation is used to separate the flexible substrate from the carrier substrate, then the separation can be achieved, but the device structure is affected and defects increase
Solution Approach 1:
The patent applies preliminary action by forming a sacrificial layer with specific adhesive properties before device fabrication. This sacrificial layer is designed to have controlled adhesion to both the carrier substrate and flexible substrate, enabling subsequent easy separation without laser or light irradiation. The sacrificial layer acts as a pre-prepared separation interface that eliminates the need for harmful post-fabrication irradiation processes.
2Ease of manufacture
If laser or light irradiation system and separate process are added for separation, then the flexible substrate can be separated, but the fabrication process becomes complex and cost increases
Solution Approach 1:
The patent merges the separation function into the existing sacrificial layer structure used during device fabrication. Instead of adding a separate laser irradiation process, the sacrificial layer is designed to provide both its traditional function (supporting the flexible substrate during fabrication) and an additional function (enabling easy separation). This integration eliminates the need for separate separation equipment and processes, reducing overall fabrication complexity.
3Strength
If an additional adhesive layer is formed between the sacrificial layer and flexible substrate to improve adhesion, then adhesion is sufficient, but the process becomes more complicated and separation conditions become more severe
Solution Approach 1:
The patent applies local quality by creating different adhesive characteristics at different interfaces of the sacrificial layer. The sacrificial layer is designed to have strong adhesion to the carrier substrate (to maintain structural integrity during fabrication) and controlled, reversible adhesion to the flexible substrate (to enable easy separation). This localized differentiation of adhesive properties allows the single-layer sacrificial structure to fulfill both adhesion and easy separation requirements without adding extra adhesive layers.
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 approach simplifies the fabrication process, reduces costs, and enhances the reliability and characteristics of flexible display devices by enabling easy separation of the flexible substrate using a physical stimulus, thereby eliminating the risks associated with laser or light irradiation.
Implementation Method 1
the first polyimide resin layer has a coefficient of thermal expansion (CTE) equal to or lower than the CTE of the second polyimide resin layer at a temperature of 100 to 200° C.
Data Source
AI summary
A method for producing a device substrate by obtaining a laminate comprising a carrier substrate with a first polyimide film disposed on at least one surface of the carrier substrate, a second polyimide film disposed on the first polyimide film, applying a physical stimulus to the second polyimide film without causing chemical changes in the first polyimide film such that the adhesive strength of the first polyimide to the second polyimide film decreases and separating the second polyimide film from the first polyimide film formed on the carrier substrate to obtain the device.