Low Dielectric PPE-LCP Composite for High-Frequency PCBs
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Solution Overview
Problem
Polyphenylene ether (PPE) resin, used in high-frequency printed circuit boards, faces challenges such as high melting viscosity, poor solvent resistance, and difficulty in operating above 250°C due to its thermal properties, leading to compatibility issues with crosslinking agents and curable resins, which compromises its dielectric and mechanical properties.
Innovation Solution
A low dielectric material comprising 5-50 parts by weight of PPE resin, 10-90 parts by weight of liquid crystal polymer with an allyl group, 0.01-15 parts by weight of bismaleimide resins, and 0.01-10 parts by weight of polymer additives, along with crosslinking agents, catalysts, and fillers like fused silica, to enhance thermal conductivity, mechanical strength, and reduce thermal expansion and water absorption, while maintaining excellent dielectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PPE resin is used for high frequency PCB, then dielectric properties are improved, but processability deteriorates due to high melting viscosity
Solution Approach 1:
The patent combines PPE resin with liquid crystal polymer (LCP) having specific molecular weight range (1000-5000) and narrow distribution (Mw/Mn=1.0-1.8). This composite formulation maintains the excellent dielectric properties of PPE while the specific LCP components improve processability by reducing melting viscosity and enhancing flow characteristics during manufacturing.
Solution Approach 2:
The patent specifies precise parameter ranges for the resin components: PPE resin with Mw of 1000-7000 and Mn of 1000-4000, and LCP with Mw of 1000-5000 and Mn of 1000-4000. By controlling these molecular weight parameters and their distribution, the material achieves optimal balance between dielectric performance and processability, enabling easy handling during PCB manufacturing.
2Reliability
If PPE resin is used in copper-clad laminate, then dielectric properties are improved, but solvent resistance deteriorates causing interlayer film release
Solution Approach 1:
The patent creates a composite system where PPE resin is combined with specific liquid crystal polymer components. This composite structure provides synergistic effects: PPE maintains dielectric properties while the LCP component enhances solvent resistance, preventing interlayer film release during the solvent clean step in PCB manufacturing processes.
3Reliability
If PPE resin is used for high temperature operation, then dielectric properties are maintained, but mechanical integrity deteriorates above 250°C due to melting point close to Tg
Solution Approach 1:
The patent formulates a composite material where PPE resin is combined with liquid crystal polymer having specific molecular weight characteristics. This composite structure elevates the overall thermal stability: while PPE maintains dielectric properties at high temperatures, the LCP component raises the melting point above 250°C, ensuring mechanical integrity is preserved during soldering processes and high-temperature operations.
4Temperature
If crosslinking modification is applied to PPE resin, then thermal resistance is improved, but compatibility deteriorates due to polar difference with active functional groups
Solution Approach 1:
The patent introduces liquid crystal polymer as an intermediary component that bridges the compatibility gap. The LCP acts as a mediator between PPE resin and crosslinking agents, reducing the polar difference and improving compatibility. This allows crosslinking modification to proceed effectively while maintaining homogeneous mixture and proper curing characteristics.
5Temperature
If curable resins are introduced to PPE resin, then thermal resistance is improved, but dielectric properties deteriorate due to incompatibility
Solution Approach 1:
The patent uses liquid crystal polymer as an intermediary to ensure compatibility between PPE resin and curable resins. This mediator prevents phase separation and maintains homogeneous distribution, allowing the curable resin to enhance thermal resistance through crosslinking while the PPE component preserves its excellent dielectric properties in the final cured material.
Data Source
AI summary
The invention provides a low dielectric material. The low dielectric material comprises: (i) 5-50 parts by weight of polyphenylene ether (PPE) resin having a Mw of 1000˜7000, a Mn of 1000-4000 and Mw/Mn=1.0-1.8; and (ii) 10-90 parts by weight of liquid crystal polymer with allyl group having a Mw of 1000˜5000, a Mn of 1000-4000 and Mw/Mn=1.0-1.8, wherein the dielectric material has Dk of 3.4-4.0 and Df of 0.0025-0.0050. The dielectric material is suitably used in prepregs and insulation layers of a circuit board, because it has high Tg, low thermal expansion coefficient, low moisture absorption and excellent dielectric properties such as Dk and Df.