PPE Prepreg Molecular Weight Optimization for PCB Adhesion
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Solution Overview
Problem
High-molecular-weight polyphenylene ether (PPE) prepregs exhibit high melting points and insufficient adhesiveness, leading to molding failures such as voids and thin spots in multilayer printed wiring boards, making it difficult to achieve reliable multilayer printed wiring boards with high adhesiveness to base materials.
Innovation Solution
A prepreg comprising a base material, specifically a glass cloth with a dielectric constant of 6.8 or less, and a polymer with structural units represented by specific formulae, along with a curable compound, curing aid, and inorganic filler, which enhances adhesiveness and reliability by improving melt viscosity and adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-molecular-weight PPE is used as the polymer, then high-frequency characteristics (dielectric constant and dielectric loss) are improved, but melting point increases and adhesiveness deteriorates
Solution Approach 1:
The patent changes the molecular weight parameter of the PPE polymer to a specific range (weight-average molecular weight: 10,000 to 100,000) to simultaneously achieve good high-frequency characteristics and adequate adhesiveness. This parameter optimization resolves the contradiction by finding the optimal balance point where dielectric properties remain excellent while melting point and adhesiveness are improved compared to high-molecular-weight PPE.
2Reliability
If high-molecular-weight PPE is used to maintain dielectric properties, then signal transmission quality is improved, but melt viscosity increases causing molding failures
Solution Approach 1:
The patent optimizes the molecular weight parameter of PPE to achieve an optimal balance between dielectric properties and processability. By controlling the weight-average molecular weight within 10,000 to 100,000, the resin maintains excellent high-frequency characteristics while achieving adequate melt viscosity for successful multilayer molding without voids or thin spots.
3Strength
If PPE with sufficient adhesiveness is selected, then bonding strength to base material is improved, but high-frequency characteristics deteriorate
Solution Approach 1:
The patent optimizes the molecular weight parameter of PPE to achieve an optimal balance between adhesiveness and dielectric properties. By controlling the weight-average molecular weight within 10,000 to 100,000, the resin achieves adequate adhesiveness to base materials and other members while maintaining excellent high-frequency characteristics that would be lost with lower molecular weight variants.
Data Source
AI summary
Provided is a prepreg for producing a multilayer printed wiring board having high reliability and being excellent in adhesiveness with respect to a base material or the like. The prepreg includes: a base material; and a polymer having a structural unit represented by at least one kind of the following formulae (1-1), (1-2), and (1-3).