Transparent Polyimide Laminate for Uniform Peelable Adhesion

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Solution Overview

Problem

Existing laminates using polyimide films and inorganic substrates face challenges in achieving uniform adhesive strength, colorlessness, and transparency, especially for large-area applications, leading to difficulties in peeling off the inorganic substrate without device destruction and alignment issues during multi-layer structure formation.

Innovation Solution

A manufacturing method that involves coating the inorganic substrate and polyimide film with a silane coupling agent, followed by wetting with an aqueous medium and extruding it between the layers to control the adhesive strength uniformly, minimizing blister defects and ensuring a thin, homogeneous silane coupling agent layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a silane coupling agent layer is used to bond the polyimide film to the inorganic substrate, then adhesive strength is improved, but uniform adhesive strength control becomes difficult

Engineering Contradiction:
Improveadhesive strengthVSAvoiduniform adhesive strength control
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention controls the film thickness of the silane coupling agent layer within a specific range (1 nm to 10 nm) to achieve uniform adhesive strength. By precisely controlling this critical parameter, the invention resolves the contradiction between achieving sufficient adhesive strength and maintaining uniformity across large areas.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a very thin film of silane coupling agent (1 nm to 10 nm), which is a partial amount rather than a thick layer. This thin film provides sufficient adhesive strength while enabling uniform control across large-area substrates, resolving the contradiction between strength and uniformity.

Inventive Principle:
Principle #16Partial or excessive action

2Temperature

If a polymer solution or polymer precursor solution is applied onto an inorganic substrate to form a polyimide film, then heat resistance is improved, but the film becomes brittle and easily torn

Engineering Contradiction:
Improveheat resistanceVSAvoidfilm toughness
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The invention creates a composite structure consisting of the inorganic substrate, silane coupling agent layer, and polyimide film. This composite structure combines the heat resistance of the polyimide film with the mechanical strength provided by the silane coupling agent layer, resolving the contradiction between heat resistance and film toughness.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The silane coupling agent layer acts as an intermediary between the inorganic substrate and the polyimide film. This intermediate layer improves the overall toughness and flexibility of the composite structure while maintaining the heat resistance of the polyimide film, preventing the film from being brittle and easily torn.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a thick silane coupling agent layer is used to ensure sufficient adhesive strength, then bonding reliability is improved, but blister defects increase and uniformity decreases

Engineering Contradiction:
Improvebonding reliabilityVSAvoidblister defects
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention optimizes the film thickness parameter of the silane coupling agent layer to within 1 nm to 10 nm. This precise parameter control ensures sufficient bonding reliability while minimizing blister defects that occur with thicker layers, resolving the contradiction between reliability and defect reduction.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a minimal thickness of silane coupling agent (1 nm to 10 nm), which is just sufficient to provide reliable bonding. This partial amount avoids the formation of blisters that occur with excessive thickness, resolving the contradiction between bonding reliability and blister defect prevention.

Inventive Principle:
Principle #16Partial or excessive action

4Stability of the object's composition

If the polyimide film is bonded to the inorganic substrate with strong adhesive strength, then manufacturing stability is improved, but peeling off becomes difficult and device destruction occurs

Engineering Contradiction:
Improvemanufacturing stabilityVSAvoidpeeling difficulty
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The invention controls the film thickness of the silane coupling agent layer within 1 nm to 10 nm, which provides stable bonding during manufacturing while allowing controlled peeling after device formation. This parameter control resolves the contradiction between manufacturing stability and peeling ease.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a thin film of silane coupling agent that provides just enough bonding strength for stable manufacturing processes, but allows for controlled peeling after device formation. This partial amount of adhesive material resolves the contradiction between manufacturing stability and peeling difficulty.

Inventive Principle:
Principle #16Partial or excessive action

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 method enables control of adhesive strength between 0.06 N/cm and 0.25 N/cm, reduces blister defects, and allows for large-area laminates with high-quality flexible electronic devices, ensuring easy peeling without device destruction and precise alignment.

Implementation Method 1

a silane coupling agent layer... bonded to an inorganic substrate

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

wetted with an aqueous medium and extruded between the inorganic substrate and the polyimide film

Methodology Applied
Scientific EffectWetting: Wetting

Data Source

PatentUS12472732B2Laminate, method for manufacturing laminate, and method for manufacturing flexible electronic device
Publication Date: 2025.11.18 TOYOBO CO LTD

AI summary

The purpose is to provide a laminate useful as a temporary support for producing a large-area, high-definition flexible electronic device, the laminate having stably low adhesive strength between a colorless and highly transparent polyimide film and an inorganic substrate even in the case of a large surface area and having few blister defects. The laminate that attains the purpose is obtained by initially wetting either one of an inorganic substrate coated with the silane coupling agent and a colorless polyimide film with an aqueous medium, and then laminating while pressing out the aqueous medium.