Aromatic Polyether Substrate for Flexible Wiring

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Solution Overview

Problem

Substrates for flexible printed wiring face challenges in achieving high light transmission, heat resistance, mechanical strength, and resistance to thermal coloration, particularly due to the yellow-brown coloration caused by charge transfer complexes in aromatic polyimides, which limits their application in devices requiring transparency and high-temperature processing.

Innovation Solution

A substrate comprising an aromatic polyether-typed polymer with a glass transition temperature of 230° C. to 350° C., formed from specific structural units, which provides excellent transparency, heat resistance, and resistance to thermal coloration, allowing for high light transmission and robust mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If aromatic polyimide is used for FPC substrate, then heat resistance is improved, but light transmission property deteriorates due to yellow-brown coloration

Engineering Contradiction:

Improveheat resistanceVSAvoidlight transmission property

Core Design Contradiction:

TemperatureVSIllumination intensity

Solution Approach 1:

The patent changes the chemical structure parameters of the polymer by introducing specific aromatic polyether units with particular molecular weights and compositions (controlling the ratio of structural units I and II), which fundamentally alters the material's optical properties while maintaining thermal stability, eliminating the yellow-brown coloration issue

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite polymer structure combining aromatic polyether units with specific structural units (I and II) in controlled ratios, achieving a material that integrates both high light transmission and heat resistance properties that neither component alone could provide

Inventive Principle:

Principle #40Composite materials

2Temperature

If polyimide film is formed, then heat resistance is improved, but manufacturing complexity increases due to high-temperature imidization process

Engineering Contradiction:

Improveheat resistanceVSAvoidmanufacturing process

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent changes the processing temperature parameter by designing a polymer that achieves high heat resistance without requiring high-temperature imidization, enabling film formation at lower temperatures through alternative chemical structures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention extracts the high-temperature imidization step from the manufacturing process by using pre-formed aromatic polyether structures that do not require thermal imidization, simplifying the production process while maintaining heat resistance

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of operation

If conventional polymer is used, then flexibility is maintained, but resistance to thermal coloration deteriorates at high temperature

Engineering Contradiction:

ImproveflexibilityVSAvoidresistance to thermal coloration

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by incorporating specific aromatic polyether units with controlled molecular weights and structural unit ratios, which inherently resist thermal coloration while preserving the flexibility needed for FPC applications

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9028949B2Substrate for printed wiring and resin composition used therefor

Publication Date: 2015.05.12 JSR CORPORATION

AI summary

There are provided a substrate for printed wiring excellent in light transmission property, heat resistance, mechanical strength and resistance to thermal coloration; a printed wiring laminate; and a resin composition used to produce the substrate and the laminate. The substrate for printed wiring comprises an aromatic polyether-typed polymer having a glass transition temperature, as measured by differential scanning calorimetry (DSC, heating rate: 20° C./minute), of from 230° C. to 350° C.