Polyimide Plastic Substrate for Touch Screen Panels

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Solution Overview

Problem

Conventional touch screen panels face issues with light transmittance deterioration, complex processing, and high production costs due to the use of polyethylene terephthalate (PET) films, which have low heat resistance and are prone to deformation during heat treatment, affecting the durability and efficiency of resistive type touch screen panels.

Innovation Solution

A plastic substrate with a polyimide film, a hard coating layer, and a transparent electrode layer, where the polyimide film is polymerized from aromatic dianhydrides and diamines, providing high light transmittance, hardness, and ITO processibility, and the hard coating layer is formed using an organic-inorganic hybrid composition, enhancing chemical resistance and simplifying the touch screen panel structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If polyethylene terephthalate (PET) film is used as substrate, then flexibility and formability are improved, but heat resistance deteriorates causing deformation during heat treatment

Engineering Contradiction:
ImproveflexibilityVSAvoidheat resistance
Core Design Contradiction:
ShapeVSTemperature

Solution Approach 1:

The patent uses a composite structure consisting of a PET film substrate combined with a polyimide layer. The PET film provides flexibility and formability, while the polyimide layer contributes heat resistance and dimensional stability during heat treatment processes, resolving the contradiction between flexibility and heat resistance.

Inventive Principle:
Principle #40Composite materials

2Reliability

If multiple laminated films are used to improve durability, then reliability is improved, but device complexity increases

Engineering Contradiction:
ImprovedurabilityVSAvoidnumber of laminated films
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functional layers into an integrated structure where the PET film substrate and polyimide layer work together as a unified composite material. This merging approach provides the durability of multiple layers while reducing the complexity of assembling and managing separate laminated films.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If conventional PET film with low heat resistance is used, then ease of manufacture is improved, but manufacturing precision deteriorates due to deformation during heat treatment

Engineering Contradiction:
Improveease of manufactureVSAvoiddimensional stability
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The composite structure of PET film combined with polyimide layer maintains the ease of manufacture of PET while the polyimide component provides dimensional stability during heat treatment, preventing deformation and ensuring manufacturing precision.

Inventive Principle:
Principle #40Composite materials

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 plastic substrate achieves high light transmittance, hardness, and low surface resistance, reducing the number of laminated films and simplifying the touch screen panel structure, while maintaining stability during the ITO process, thus improving durability and production efficiency.

Implementation Method 1

a polyimide film including imides of polyimide resin precursors prepared by polymerization of aromatic dianhydrides, aromatic dicarbonyl compounds and aromatic diamines

Methodology Applied
Scientific EffectPolymerization:

Data Source

PatentEP2800104B1Plastic substrate
Publication Date: 2021.01.27 KOLON INDUSTRIES INC

AI summary

The present invention provides a plastic substrate, including: a polyimide film; a hard coating layer formed on one side of the polyimide film; and a transparent electrode layer formed on the other side of the polyimide film. The plastic substrate has excellent light transmittance high hardness characteristics, superior ITO processibility and flexibility. Further, the plastic substrate can function as both a window film and an electrode film when it is applied to a touch screen panel. Thus, the present invention provides a touch screen panel which can be slimmed by reducing the number of laminated films including the plastic substrate.