Low Dk/Df Solder Resistant Composition for High-Frequency PCBs
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Solution Overview
Problem
Current solder resistant compositions for printed circuit boards have high dielectric constants and dissipation factors, which hinder high-frequency and high-speed signal transmission, and lack the necessary physical properties such as adhesion and heat resistance.
Innovation Solution
A novel low Dk/Df solder resistant composition is developed, comprising a photopolymerizable prepolymer made from dicyclo pentadiene-phenol novolac or polyphenyl ether modified epoxy resins, reacted with mono carboxylic acids and saturated or unsaturated anhydrides, along with an epoxy compound, photopolymerization initiator, inorganic filler, catalyst, and organic solvent, to achieve reduced dielectric constants and dissipation factors, enhanced adhesion, and improved heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional epoxy resin composition is used for solder resistant coating, then good adhesion and physical properties are achieved, but dielectric constant and dissipation factor are too high for high-frequency signal transmission
Solution Approach 1:
The patent changes the chemical composition parameters of the epoxy resin system by introducing specific low-Dk components (polyester-modified epoxy resin with Dk<3.0, polybutadiene-modified epoxy resin) and adjusting the ratio of epoxy resin to curing agent, thereby achieving both low dielectric constant and good adhesion simultaneously
Solution Approach 2:
The patent creates a composite epoxy resin system combining multiple resin components (polyester-modified epoxy, polybutadiene-modified epoxy, and conventional epoxy resin) with specific proportions to achieve the synergistic effect of low Dk/Df and excellent adhesion properties
2Object-generated harmful factors
If low dielectric constant materials are used to reduce Dk/Df, then signal transmission characteristics improve, but adhesion and heat resistance may deteriorate
Solution Approach 1:
The patent optimizes the molecular weight and composition parameters of the low-Dk epoxy resins, selecting specific polyester-modified and polybutadiene-modified epoxy resins that maintain low dielectric constants while preserving adhesion and heat resistance through controlled chemical structure
Solution Approach 2:
The patent develops a composite curing system combining epoxy resin with specific curing agents (polybasic anhydride, isocyanate, or hydroxyl-terminated polybutadiene) in optimized ratios to achieve crosslinked networks that simultaneously provide low Dk/Df and excellent mechanical/thermal properties
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 dielectric constants below 3.20 and dissipation factors below 0.015, providing excellent adhesion, chemical resistance, and heat resistance, making it suitable for high-frequency and high-speed printed circuit boards.
Implementation Method 1
the solder resistant composition formed by the photopolymerizable prepolymer (oligomer) prepared from multifunctional phenolic aldehyde epoxy acrylic resin or multifunctional o-cresol formaldehyde epoxy acrylate to which polybasic anhydride-anhydride is added and the epoxy resin composition after heating and hardening when the ultraviolet ray is applied to hardening
Data Source
AI summary
A low dielectric constant (Dk) and dissipation factor (Df) of solder resistant mask composition comprising (A) a photopolymerizable prepolymer of formula (1); (B) a photopolymerizable vinyl monomer; (C) an epoxy compound; (D) a photopolymerization initiator; (E) an inorganic filler; (F) a catalyst; and (G) an organic solvent. The low dielectric constant (Dk) and dissipation factor (Df) of solder resistant mask composition has excellent photo and thermocurability, and high developability resolution with an alkaline aqueous solution, wherein the dielectric constant is below 3.20 (1 GHz), and the dissipation factor is less than 0.015 (1 GHz);