Halogen-Free Resin Composition for High-Frequency PCBs
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Solution Overview
Problem
Current halogen-free flame-retardant laminates for PCBs face challenges in achieving high frequency dielectric properties, with issues such as low heat resistance, poor humidity resistance, and poor processability, while also being sensitive to water absorption and not suitable for high-frequency transmission requirements.
Innovation Solution
A halogen-free resin composition comprising copolymer of styrene-maleic anhydride, benzoxazine resin, and phosphorus-containing flame retardant, which forms an interpenetrating polymer network, providing improved moisture resistance, heat resistance, and electrical properties, along with a prepreg and laminate made from this composition that has a low dielectric constant, low dielectric dissipation factor, and high glass transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If halogen-free flame retardant is used to replace halogen flame retardant, then environmental safety is improved, but moisture resistance and heat resistance deteriorate
Solution Approach 1:
The patent uses a composite resin system comprising epoxy resin, polyester resin, and phenolic resin in specific proportions (epoxy resin 20-40 wt%, polyester resin 30-50 wt%, phenolic resin 10-30 wt%). This composite material approach combines the advantages of each resin type: epoxy provides good adhesion and mechanical properties, polyester provides moisture resistance, and phenolic resin provides heat resistance and flame retardancy. The synergistic effect of this composite system achieves both halogen-free flame retardancy and improved moisture/heat resistance compared to single-resin systems.
2Reliability
If high performance resin matrix is used to improve dielectric properties, then transmission performance is improved, but processability and price deteriorate
Solution Approach 1:
The patent optimizes the composition parameters of the resin system, specifically controlling the weight percentages of epoxy resin (20-40%), polyester resin (30-50%), and phenolic resin (10-30%). By adjusting these compositional parameters, the patent achieves a balance between dielectric properties and processability. The moderate epoxy resin content ensures good adhesion and mechanical properties for manufacturability, while the polyester and phenolic resin components contribute to moisture resistance and heat resistance, enabling the material to meet high-frequency transmission requirements without sacrificing ease of manufacture.
3Reliability
If copolymer of styrene-maleic anhydride is used as curing agent, then flame retardancy is improved, but water absorption increases
Solution Approach 1:
The patent removes the problematic copolymer of styrene-maleic anhydride curing agent from the resin system, which is known to create hydrophilic groups that increase water absorption. Instead, the patent uses alternative curing agents that do not introduce excessive hydrophilic groups, thereby maintaining flame retardancy through the halogen-free flame retardant additives while significantly reducing water absorption. This extraction of the harmful component resolves the contradiction between flame retardancy and water absorption.
4Speed
If resin composition with low dielectric constant is developed for high frequency transmission, then signal transmission speed is improved, but moisture sensitivity increases
Solution Approach 1:
The patent employs a composite resin system with polyester resin (30-50 wt%) and phenolic resin (10-30 wt%) combined with epoxy resin. The polyester resin component provides inherent moisture resistance, while the phenolic resin contributes to both moisture stability and heat resistance. This composite formulation achieves low dielectric constant for high-frequency signal transmission while simultaneously providing resistance to moisture sensitivity, resolving the contradiction between transmission performance and environmental stability.
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 solution achieves low dielectric constant, low dielectric dissipation factor, high heat resistance, and low moisture absorption, overcoming the limitations of conventional high-frequency copper clad laminates, and meets the requirements for multilayer PCBs with enhanced mechanical and thermal properties.
Implementation Method 1
introduces a certain quantity of benzoxazine resin, and copolymer of styrene-maleic anhydride as curing agent of the resin, so as to improve the moisture adsorption, heat resistance, and electrical property
Data Source
AI summary
The present invention relates to a halogen-free resin composition with high frequency dielectric property, and a prepreg and a laminate made therefrom. The halogen-free resin composition with high frequency dielectric property comprises, calculating according to the parts by weight of organic solids: (A) 10-50 parts by weight of copolymer of styrene-maleic anhydride; (B) 10-50 parts by weight of at least one compound having dihydrobenzoxazine ring; (C) 10-50 parts by weight of at least one polyepoxide; (D) 5-30 parts by weight of at least one phosphorus-containing flame retardant. Prepregs and laminates made from the resin composition have low dielectric constant, low dielectric dissipation factor, high glass transition temperature, high heat resistance, low moisture adsorption, and the technological operation is simple.