Phosphorus-Containing Polyimides for Flexible PCBs

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Solution Overview

Problem

Traditional flame-resistant compositions, such as those containing halogen compounds, pose environmental contamination risks and fail to effectively inhibit the formation of charge-transfer complexes in polyimide films, leading to dark colors and poor mechanical properties.

Innovation Solution

Development of novel phosphorus-containing compounds, specifically derivatives of phosphorus-containing diphenol (HPP), which are used to synthesize polyamides and polyimides with phosphorus in the side chain, inhibiting charge-transfer complex formation and improving mechanical properties and transparency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If halogen-containing flame resistant compositions are used, then flame resistance is improved, but environmental contamination and toxicity increase

Engineering Contradiction:

Improveflame resistanceVSAvoidenvironmental contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes harmful halogen elements from the flame resistant composition, replacing them with phosphorus-containing compounds. This extraction eliminates the source of environmental contamination and toxicity while maintaining the desired flame resistance function through alternative chemical mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs phosphorus-containing diphenol derivatives as readily available, cost-effective alternatives to expensive halogen-based flame retardants. These compounds provide effective flame resistance without the long-term environmental persistence and toxicity associated with halogenated materials.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Temperature

If conventional polyimide films are used, then thermal stability is improved, but color deepening and light absorption increase

Engineering Contradiction:

Improvethermal stabilityVSAvoidlight absorption

Core Design Contradiction:

TemperatureVSIllumination intensity

Solution Approach 1:

The invention introduces phosphorus-containing side chains at specific local positions within the polyimide structure. These localized phosphorus groups selectively inhibit charge-transfer complex formation in the vicinity of the polymer backbone, reducing color deepening and light absorption while preserving the overall thermal stability provided by the polyimide framework.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite polyimide structure combining the thermally stable polyimide backbone with phosphorus-containing diphenol side chains. This composite architecture integrates the thermal performance of polyimide with the optical benefits of phosphorus-based charge-transfer inhibition, achieving both thermal stability and reduced light absorption.

Inventive Principle:

Principle #40Composite materials

3Illumination intensity

If aromatic diamine with bulky groups is used, then charge-transfer complex formation is inhibited, but mechanical properties and flexibility deteriorate

Engineering Contradiction:

Improvecolor reductionVSAvoidmechanical properties

Core Design Contradiction:

Illumination intensityVSStrength

Solution Approach 1:

The phosphorus-containing diphenol side chains act as intermediary groups that mediate between the aromatic diamine and the polyimide backbone. These intermediary phosphorus groups effectively inhibit charge-transfer complex formation and reduce color deepening, while their flexible ether linkages maintain polymer chain mobility and mechanical properties, avoiding the brittleness associated with bulky aromatic substituents.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical parameters of the side chains by introducing phosphorus-containing diphenol groups with ether linkages instead of bulky aromatic groups. This parameter change maintains the charge-transfer inhibition function while improving mechanical properties and flexibility through the more flexible phosphorus-based structure.

Inventive Principle:

Principle #35Parameter changes

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 use of HPP derivatives results in polyimides with improved transparency, mechanical properties, and reduced color, making them suitable for flexible printed circuit board materials while avoiding environmental hazards associated with halogen-based flame retardants.

Implementation Method 1

phosphorus-containing compound 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) has active hydrogen atoms capable of reacting with electron deficient compounds

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentUS9527962B2Phosphorous-containing compounds and their preparation process and use

Publication Date: 2016.12.27 CHANG CHUN PLASTICS CO LTD

AI summary

A series of novel phosphorus-containing compounds having the following formula is provided:in which:R1-R4, A, Q and m are as defined in the specification.A process for the preparation of the compound of formula (I) is also provided. A polymer of formula (PA), and preparation process and use thereof are further provided. A polymer of formula (PI), and preparation process and use thereof are also provided.