Thermosetting Resin Composition for High-Frequency PCBs
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Solution Overview
Problem
Current copper clad laminates face challenges with high dielectric constants and dielectric loss tangents, brittleness, and insufficient heat resistance, making them unsuitable for high-frequency and high-speed applications, particularly in multilayer printed circuit boards.
Innovation Solution
A thermosetting resin composition comprising a solvent-soluble polyfunctional vinyl aromatic copolymer and polybutadiene resin, with specific molecular weight and structural unit ratios, which enhances crosslinking density, toughness, and dielectric properties, and is formulated to prevent polar group formation, ensuring low water absorption and improved heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy resin is used for circuit boards, then adhesion characteristics are excellent, but dielectric constant and dielectric loss tangent are high, resulting in insufficient high frequency characteristics
Solution Approach 1:
The invention uses a composite resin system combining polyphenylene ether (PPE) as the base resin with polyfunctional vinyl aromatic compounds as crosslinking agents. This composite approach achieves both excellent adhesion characteristics and superior high-frequency dielectric properties, with dielectric loss tangent Df of 0.006 or less and dielectric constant Dk of 3.2 or less, while maintaining strong adhesion to copper foils and glass fiber cloths.
Solution Approach 2:
The invention optimizes the molecular weight parameters of the polyfunctional vinyl aromatic compound, specifically controlling the number average molecular weight Mn to be 500-30,000 and the weight average molecular weight Mw to be 2,000-60,000, with Mw/Mn ratio of 1.05-2.0. These parameter changes enable the resin to achieve both good adhesion and excellent high-frequency characteristics.
2Reliability
If curable crosslinking hydrocarbon resin is used, then dielectric loss tangent is low and fluidity is good, but heat resistance is insufficient
Solution Approach 1:
The invention creates a composite system where polyphenylene ether (providing heat resistance with decomposition temperature Td of 400°C or more) is combined with curable crosslinking hydrocarbon resin (providing low dielectric loss tangent Df of 0.006 or less). This composite approach successfully achieves both low dielectric loss and high heat resistance, eliminating the trade-off between these properties.
3Reliability
If soluble polyfunctional vinyl aromatic copolymer is used, then dielectric properties and heat resistance are improved, but brittleness increases, causing serious wear of drill and delamination
Solution Approach 1:
The invention optimizes the molecular weight parameters of the vinyl aromatic copolymer, controlling Mn to be 500-30,000 and Mw to be 2,000-60,000, with Mw/Mn ratio of 1.05-2.0. This parameter optimization reduces brittleness while maintaining good dielectric properties and heat resistance, preventing drill wear and delamination issues.
Solution Approach 2:
The invention combines vinyl aromatic copolymer with polyphenylene ether and other resins to create a composite system that balances toughness and dielectric properties. The composite formulation maintains dielectric loss tangent Df of 0.006 or less while improving impact resistance and reducing brittleness, thereby preventing processing defects.
4Strength
If thermoplastic resin is added to improve toughness, then toughness is improved, but glass transition temperature is greatly lowered and phase separation occurs, causing delamination after lead-free reflow soldering
Solution Approach 1:
Instead of using thermoplastic resins that cause long-term reliability issues, the invention employs vinyl aromatic copolymers with optimized molecular weights that provide adequate toughness without compromising thermal stability. This approach achieves necessary toughness while maintaining glass transition temperature and preventing phase separation during lead-free reflow soldering.
5Strength
If high dielectric constant resin is used, then adhesion is excellent, but signal transmission loss increases for high-frequency signals
Solution Approach 1:
The invention creates a composite resin system that achieves both excellent adhesion and low signal transmission loss. The formulation achieves dielectric constant Dk of 3.2 or less and dielectric loss tangent Df of 0.006 or less, while maintaining strong adhesion to copper foils and glass fiber cloths, thus eliminating the trade-off between adhesion and signal transmission 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 solution provides copper-clad laminates with improved toughness, drilling processability, and reliability for high-frequency applications, maintaining high glass transition temperatures and excellent dielectric properties, suitable for high-speed and multilayer printed circuit boards.
Implementation Method 1
a thermosetting resin composition comprising component (A) a soluble polyfunctional vinyl aromatic copolymer and component (B) polybutadiene resin
Implementation Method 2
formulated to prevent polar group formation, ensuring low water absorption and improved heat resistance
Data Source
AI summary
The present invention provides a thermosetting resin composition, and a prepreg and metal foil clad laminate prepared from same. The thermosetting resin composition comprises: a component (A): a solvent-soluble polyfunctional vinyl aromatic copoly mer, the copolymer being a polyfunctional vinyl aromatic copolymer having a structural unit derived from a monomer including a divinyl aromatic compound (a) and an ethyl vinyl aromatic compound (b); and a component (B): selected from a polybutadiene resin having a number-average molecular weight of 500 to 10,000, the content of vinyl addition across 1, 2 positions in the molecule of the polybutadiene resin being 50% or more. The prepreg and the copper foil clad laminate prepared from the thermosetting resin composition of the present invention have a good toughness, maintain a high glass-transition temperature and a low water absorption, dielectric property and heat and humidity resistance, and are suitable for use in the field of high-frequency high-speed printed circuit boards and for processing of multilayer printed circuit boards.