Halogen-Free Epoxy Resin Composition for Printed Circuit Boards
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Solution Overview
Problem
Conventional laminates for printed circuits using brominated flame retardants produce harmful combustion products and have limitations in thermal resistance and dielectric properties, while halogen-free alternatives face challenges in achieving high glass transition temperature and low water absorption.
Innovation Solution
A halogen-free thermosetting resin composition comprising a halogen-free epoxy resin, phosphorus-containing bisphenol, dicyclopentadiene novolac, and a phosphorus-containing flame retardant, which synergistically enhance glass transition temperature, thermal resistance, and dielectric performance, while ensuring halogen-free flame retardance and low water absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brominated epoxy resin is used to achieve flame retardance, then flame retardancy is improved, but harmful combustion products are generated
Solution Approach 1:
The patent replaces harmful brominated flame retardants with phosphorus-containing bisphenol as a curing agent. The phosphorus-containing bisphenol provides flame retardancy through phosphorus-based mechanisms rather than halogen-based mechanisms, thereby eliminating the generation of hydrogen bromide and carcinogenic dioxins while maintaining the required flame retardant performance.
Solution Approach 2:
The patent changes the chemical composition parameters by using phosphorus-containing bisphenol with specific molecular structure (where n is an integer from 2 to 20) as the curing agent instead of conventional brominated epoxy resin. This parameter change in the chemical composition fundamentally alters the combustion chemistry to eliminate harmful halogenated products while maintaining flame safety.
2Ease of operation
If dicyandiamide is used as curing agent for FR-4 materials, then process operability is improved, but thermal decomposition temperature is reduced
Solution Approach 1:
The patent changes the curing agent from dicyandiamide to phosphorus-containing bisphenol. This parameter change results in a cured system with higher thermal decomposition temperature due to the stronger chemical bonds and crosslinked structure formed by phosphorus-containing bisphenol, while maintaining adequate process operability through controlled curing characteristics.
Solution Approach 2:
The patent creates a composite curing system combining phosphorus-containing bisphenol with dicyclopentadiene novolac. This composite approach leverages the high thermal stability of phosphorus-containing bisphenol while the novolac component contributes to processability and adhesion, achieving both improved thermal resistance and acceptable process operability.
3Temperature
If phenolic resin is used as epoxy curing agent for lead-free process, then thermal resistance is improved, but dielectric properties are deteriorated
Solution Approach 1:
The patent changes the curing agent from phenolic resin to phosphorus-containing bisphenol. This parameter change maintains the high thermal resistance benefit (with glass transition temperature above 150°C) while improving dielectric properties by reducing water absorption and eliminating the benzene ring structure that causes dielectric deterioration in phenolic-resin-cured systems.
Solution Approach 2:
The patent uses phosphorus-containing bisphenol as a versatile curing agent that can be adjusted in amount (5-30 parts by weight based on 100 parts of epoxy resin) to optimize both thermal and dielectric properties, replacing the fixed phenolic resin approach with a flexible phosphorus-based solution that adapts to different performance requirements.
4Object-generated harmful factors
If halogen-free alternatives are used, then environmental compliance is improved, but glass transition temperature and water absorption performance are worsened
Solution Approach 1:
The patent changes the chemical composition by using phosphorus-containing bisphenol as the curing agent. This parameter change enables the system to achieve high glass transition temperature (above 150°C) and low water absorption (below 0.1%) while remaining halogen-free, thereby simultaneously achieving environmental compliance and superior thermal-moisture performance.
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 composition achieves high glass transition temperature, excellent dielectric properties, low water absorption, and halogen-free flame retardance, meeting UL94 V-0 standards, with improved process workability and thermal resistance for printed circuit boards.
Implementation Method 1
phosphorus-containing bisphenol has the following structure... reaction groups include hydroxyl groups and phosphorus units at both sides
Implementation Method 2
phosphorus-containing flame retardant... halogen-free flame retardance... UL94 V-0
Implementation Method 3
dicyclopentadiene novolac... excellent dielectric performance and thermal resistance... low water absorption
Data Source
AI summary
The present invention relates to a halogen-free thermosetting resin composition, and also a prepreg and a laminate for printed circuit prepared from the halogen-free thermosetting resin composition. The halogen-free thermosetting resin composition comprises, based on 100 parts by weight of organic solids, (A) from 30 to 60 parts by weight of a halogen-free epoxy resin, (B) from 5 to 30 parts by weight of a first curing agent of phosphorus-containing bisphenol, (C) from 5 to 30 parts by weight of a second curing agent of dicyclopentadiene novolac, and (D) a phosphorus-containing flame retardant. The prepreg and laminate for printed circuit prepared from the halogen-free thermosetting resin composition according to the present invention have high glass transition temperature, excellent dielectric properties, low water absorption, high thermal resistance and better process workability, and can fulfill halogen-free flame retardance and achieve the grade of UL94 V-0.