Prepreg with Low Dielectric Loss Using Polar Solvent
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Solution Overview
Problem
Existing laminated boards for printed wiring boards face challenges in achieving a low dielectric loss tangent when using polar solvents, as the residual solvent content affects the prepreg's properties, and there is a need for environmentally friendly alternatives to toluene.
Innovation Solution
A prepreg is developed by impregnating a base material with a varnish containing an inorganic filler, propylene glycol monomethyl ether acetate as a polar solvent, and a resin composition with 50% or more polyphenylene ether, followed by a drying process that limits the polar solvent content to 3 mass% or less, achieving a dielectric loss tangent of 0.001-0.007 at 10 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If toluene is used as the organic solvent to achieve low dielectric loss tangent, then the dielectric properties are improved, but environmental pollution increases and the solvent is restricted for use
Solution Approach 1:
The patent changes the solvent type from non-polar toluene to polar solvents (propylene glycol monomethyl ether acetate, acetone, methyl ethyl ketone, N,N-dimethylformamide, or dimethylacetamide) while controlling the residual solvent content to 3 mass% or less. This parameter change allows achieving low dielectric loss tangent (0.001-0.007) without using environmentally restricted solvents like toluene.
2Object-affected harmful factors
If polar solvents are used as environmentally friendly alternatives to toluene, then environmental pollution is reduced, but the dielectric loss tangent increases due to residual solvent content
Solution Approach 1:
The patent controls the residual polar solvent content to 3 mass% or less through optimized drying conditions (120-200°C for 2-30 minutes). This precise parameter control enables the use of environmentally friendly polar solvents while maintaining low dielectric loss tangent values of 0.001-0.007, effectively resolving the contradiction between environmental friendliness and electrical properties.
Solution Approach 2:
The patent implements a preliminary drying step before final product formation to remove excess polar solvent. By conducting drying at 120-200°C for 2-30 minutes, the residual solvent content is reduced to 3 mass% or less in advance, ensuring that the final prepreg achieves the required low dielectric loss tangent while using environmentally friendly solvents.
3Ease of manufacture
If the residual polar solvent content is increased to improve ease of manufacture, then the manufacturing process is simplified, but the dielectric loss tangent increases
Solution Approach 1:
The patent optimizes the drying parameters (temperature of 120-200°C and time of 2-30 minutes) to achieve the right balance between ease of manufacture and dielectric properties. By controlling the residual solvent content to 3 mass% or less through these optimized parameters, the patent maintains low dielectric loss tangent (0.001-0.007) while keeping the manufacturing process practical and efficient.
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 prepreg achieves a low dielectric loss tangent suitable for high-speed data processing devices, supports densification, and suppresses dust falling during production, ensuring stable manufacturing and improved industrial utility.
Implementation Method 1
a varnish containing an inorganic filler, a polar solvent containing at least propylene glycol monomethyl ether acetate, and a resin composition containing 50 mass% or more of polyphenylene ether
Implementation Method 2
subjecting the base material treated to a drying step, wherein the polar solvent content of the prepreg is 3 mass% or less
Data Source
AI summary
To provide a prepreg that achieves a low dielectric loss tangent, despite the use of a polar solvent. A prepreg produced by impregnating or coating a base material with a varnish comprising an inorganic filler, a polar solvent, and a resin composition principally comprising polyphenylene ether, and subjecting the base material treated to a drying step, wherein the polar solvent content of the prepreg is 3 mass% or less, and a dielectric loss tangent at 10 GHz of a laminated board produced using this prepreg is 0.001-0.007.