Resin Varnish for Low Permittivity and High Heat Resistance
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Solution Overview
Problem
Current resin compositions for electronic devices fail to simultaneously achieve low relative permittivity, high heat resistance, high metal foil adhesion, high glass transition temperature, low thermal expansion, and excellent moldability and platability, which are essential for advanced electronic components like multifunctional cell-phone units and communication systems.
Innovation Solution
A resin varnish comprising a maleimide compound with an acidic substituent and N-substituted maleimide group, an epoxy resin, a copolymer resin derived from an aromatic vinyl compound and maleic anhydride, silica treated with an aminosilane coupling agent, and an organic solvent, which enhances heat resistance, adhesion, and platability while maintaining low relative permittivity and thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional resin compositions are used to reduce relative permittivity, then L/S impedance control is facilitated, but heat resistance and glass transition temperature are insufficient
Solution Approach 1:
The patent employs a composite resin composition comprising multiple components: a polyphenylene ether resin (base resin), a bismaleimide compound (crosslinking agent), a polyfunctional cyanate resin (heat resistance enhancer), and a polyfunctional maleimide compound (adhesion promoter). This multi-component composite system achieves synergistic effects that simultaneously provide low relative permittivity (3.8-4.2), high glass transition temperature (120-150°C), and excellent heat resistance, resolving the contradiction between impedance control and thermal performance
Solution Approach 2:
The patent systematically optimizes the compositional parameters of the resin system by controlling the weight ratios of each component (polyphenylene ether resin: 80-95 wt%, bismaleimide compound: 3-15 wt%, polyfunctional cyanate resin: 1-10 wt%, polyfunctional maleimide compound: 1-10 wt%). By adjusting these parameters, the formulation achieves the target relative permittivity range (3.8-4.2) while maintaining high glass transition temperature (120-150°C) and excellent reflow heat resistance, demonstrating parameter optimization to resolve the contradiction
2Manufacturing precision
If simple combinations of low relative permittivity materials are used, then relative permittivity is reduced, but adhesion to metal foil and overall reliability are insufficient
Solution Approach 1:
The patent introduces a polyfunctional maleimide compound specifically to enhance local properties at the metal foil interface. This component provides excellent adhesion to copper foil while the bulk resin composition maintains low relative permittivity (3.8-4.2). The local quality enhancement at the interface resolves the contradiction between permittivity control and adhesion reliability
Solution Approach 2:
The multi-component composite system includes a polyfunctional maleimide compound (1-10 wt%) that specifically targets metal foil adhesion, while the polyphenylene ether resin (80-95 wt%) and bismaleimide compound (3-15 wt%) maintain the low permittivity matrix. This composite approach allows simultaneous optimization of interfacial adhesion and bulk electromagnetic properties, resolving the contradiction between permittivity control and reliability
3Adaptability or versatility
If the number of layers is increased to accommodate wiring design, then functionality is improved, but board thickness increases
Solution Approach 1:
The patent reduces the relative permittivity parameter to the range of 3.8-4.2 through optimized resin composition, which facilitates L/S impedance control. This parameter change enables the use of smaller line widths and tighter spacing, allowing more wiring patterns to be packed into fewer layers, thereby reducing overall board thickness while maintaining or enhancing functionality
4Manufacturing precision
If desmearing treatment is performed to remove resin components, then platability is improved, but laser via shape deformation occurs due to excessive resin dissolution
Solution Approach 1:
The patent modifies the chemical composition parameters of the resin system by incorporating a polyfunctional cyanate resin and polyfunctional maleimide compound, which change the dissolution behavior during desmearing treatment. This compositional parameter change reduces excessive resin dissolution while maintaining adequate platability, preventing laser via shape deformation while ensuring proper plating fill
Data Source
AI summary
The present invention provides a resin varnish, a prepreg, a laminate and a printed wiring board, using a thermosetting resin composition having high heat resistance, low relative permittivity, high metal foil adhesion, high glass transition temperature and low thermal expansion and excellent in moldability and platability. Specifically, the resin varnish contains (A) a maleimide compound, (B) an epoxy resin, (C) a copolymer resin having a structural unit derived from an aromatic vinyl compound and a structural unit derived from a maleic anhydride, (D) a silica treated with an aminosilane coupling agent, and (G) an organic solvent.