Composite Dielectric Layer for Low Loss and High Peel Strength
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Solution Overview
Problem
Developing a dielectric composition for bond ply layers in multi-layered printed circuit boards that balances minimum melt viscosity and coefficient of thermal expansion while achieving low dielectric loss and high peel strength to copper, which is challenging due to these properties typically being diametrically opposed.
Innovation Solution
A composition comprising a hydrocarbyl thermoplastic polymer, a reactive monomer capable of free-radical crosslinking, a free radical source, and functionalized fused silica, which forms a crosslinked network and enhances peel strength and reduces thermal expansion without the need for reinforcing layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional dielectric compositions are used to achieve low dielectric loss, then dielectric loss is reduced, but peel strength to copper deteriorates
Solution Approach 1:
The patent uses a composite material system comprising a thermoplastic polymer matrix combined with reactive monomers that crosslink to form a network structure. This composite approach allows simultaneous achievement of low dielectric loss (≤0.0030 at 10 GHz) and high peel strength (≥0.54 kg/cm) by combining the electrical properties of the polymer with the adhesive properties of the crosslinked network, resolving the contradiction between these two properties
2Strength
If reinforcing layers are added to increase peel strength, then peel strength is improved, but device complexity and layer thickness increase
Solution Approach 1:
The patent changes the chemical and physical parameters of the dielectric composition by incorporating reactive monomers (such as di- or tri-functional monomers) that crosslink with the thermoplastic polymer. This parameter change enables the formation of a crosslinked network within the dielectric layer itself, achieving high peel strength (≥0.54 kg/cm) without requiring additional reinforcing layers, thus maintaining simplicity in layer structure while improving strength
3Strength
If crosslinked networks are formed to improve peel strength and reduce thermal expansion, then peel strength and dimensional stability are improved, but manufacturing process complexity increases
Solution Approach 1:
The patent incorporates the reactive monomers and crosslinking agents into the dielectric composition before lamination and curing processes. The crosslinked network forms in-situ during the standard lamination process, eliminating the need for separate crosslinking steps. This preliminary incorporation of crosslinking components allows the formation of a crosslinked network (achieving peel strength ≥0.54 kg/cm and low CTE) while maintaining simplicity in the manufacturing process, as the crosslinking occurs during routine processing
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 composition achieves a high peel strength to copper of at least 0.54 kg/cm, low dielectric loss of ≤0.0030 at 10 GHz, and reduced thermal expansion, enabling thinner, unreinforced layers with improved electrical and thermal performance.
Implementation Method 1
a reactive monomer that is free-radically crosslinkable to produce a crosslinked network
Implementation Method 2
a functionalized fused silica that is capable of chemically coupling to the crosslinked network
Data Source
AI summary
In an aspect, a composition comprises a hydrocarbyl thermoplastic polymer comprising repeat units derived from an alpha-olefin and a C4-30 cycloalkene; a reactive monomer which is free-radically crosslinkable to produce a crosslinked network; a free radical source; and a functionalized fused silica capable of chemically coupling to the crosslinked network.