Polybutadiene Composite for High-Frequency Circuit Substrates
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Solution Overview
Problem
Current thermosetting resin-based high-frequency circuit substrates face challenges with high dielectric loss tangent, poor heat resistance, and inadequate thermal aging performance, making them unsuitable for high-frequency applications, particularly due to issues with solvent solubility and process operability.
Innovation Solution
A composite comprising a thermosetting resin based on polybutadiene or copolymer resin with ethylene-propylene rubber having a specific weight-average molecular weight range (100,000 to 150,000) and number-average molecular weight range (60,000 to 100,000), combined with glass fiber cloth and a curing initiator, which improves thermal oxidative aging performance and dielectric properties while maintaining good solvent solubility and process operability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermosetting polybutadiene or copolymer resin of polybutadiene and styrene is used to achieve good dielectric properties, then the dielectric constant and dielectric loss tangent are reduced, but the heat resistance deteriorates with glass transition temperature of only about 100°C
Solution Approach 1:
The patent uses a composite resin system comprising polybutadiene main chain with styrene crosslinking segments and aromatic ring-containing crosslinking segments. This composite structure combines the low dielectric loss properties of polybutadiene with the high heat resistance of aromatic rings, achieving both good dielectric properties and heat resistance simultaneously.
Solution Approach 2:
The patent optimizes the molecular weight of polybutadiene (5,000-50,000) and controls the content of styrene crosslinking segments (10-40 mol%) and aromatic ring-containing crosslinking segments (60-90 mol%). By adjusting these parameters, the resin achieves optimal balance between dielectric properties and heat resistance.
2Strength
If copolymer of butadiene and styrene is used to crosslink and improve the sticky condition of the prepreg, then the adhesive property is improved, but the process performance deteriorates and the rigidity and bending strength become very low
Solution Approach 1:
The patent introduces aromatic ring-containing crosslinking segments at specific locations in the resin molecule to provide localized rigidity and strength. The styrene crosslinking segments provide adhesive properties at the interface, while aromatic rings provide structural strength in the bulk, achieving both good adhesion and mechanical properties.
Solution Approach 2:
The patent controls the molecular weight of polybutadiene (5,000-50,000) and the ratio of different crosslinking segments to optimize the balance between adhesivity and mechanical strength. The specific molecular weight range ensures good processability while the crosslinking structure provides adequate strength.
3Reliability
If liquid ethylene-propylene rubber is used to improve the long-term retention rate of bending strength and dielectric strength, then the thermal aging performance is improved, but the solvent solubility and process operability deteriorate
Solution Approach 1:
The patent specifies a narrow molecular weight range for ethylene-propylene rubber (weight-average molecular weight 100,000-150,000 and number-average molecular weight 60,000-100,000). This precise parameter control ensures optimal balance between thermal aging resistance and solvent solubility, enabling good processability while maintaining thermal stability.
Data Source
AI summary
The present invention relates to a composite, a high-frequency circuit substrate prepared therefrom and a process for preparing the same. Such composite includes (1) from 20 to 70 parts by weight of a thermosetting mixture, including (A) a thermosetting resin based on polybutadiene or a copolymer resin of polybutadiene and styrene having a molecular weight of 11,000 or less, being composed of carbon and hydrogen elements and containing 60% or more of vinyl groups, and (B) an ethylene-propylene rubber having a weight-average molecular weight of greater than 100,000 and less than 150,000 and a number-average molecular weight of greater than 60,000 and less than 100,000 and being in a solid state at room temperature; (2) from 10 to 60 parts by weight of a glass fiber cloth; (3) from 0 to 70 parts by weight of a powder filler; and (4) from 1 to 3 parts by weight of a curing initiator. The composite of the present invention has good solvent solubility and good process operability. The high-frequency circuit substrate made by using the composite has good high frequency dielectric properties and better thermal oxidative aging performance.