Continuous Silica Fiber PCB Composite for Low Dielectric Loss
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Solution Overview
Problem
Current composite materials for printed circuit boards (PCBs) fail to meet the requirements of low dielectric loss tangents at high frequencies (e.g., >10 GHz) while maintaining mechanical strength and dimensional stability necessary for handling during production and post-processing operations.
Innovation Solution
A composite comprising a polymer layer encapsulating a fiber layer with longitudinally co-aligned continuous silica fibers, which are uniformly spaced or in contact, providing a dielectric loss tangent of less than 0.0015 at 15 GHz or higher frequencies, along with mechanical properties such as flexural modulus and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy/glass composite materials are used for PCB insulating layers, then mechanical strength and dimensional stability are improved, but dielectric loss tangent increases and becomes inadequate for GHz performance regime
Solution Approach 1:
The patent uses a composite material consisting of continuous silica fibers embedded in a polymer matrix. The silica fibers provide mechanical strength and dimensional stability, while the polymer matrix provides low dielectric loss. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both mechanical performance and low dielectric loss.
Solution Approach 2:
The patent changes the material parameters by transitioning from traditional epoxy/glass composites to a polymer/silica fiber composite system. Specifically, it uses polymers with low dielectric loss tangent (≤0.0015 at 15 GHz) and incorporates high-purity silica fibers to maintain mechanical properties while achieving the required dielectric performance for GHz applications.
2Loss of energy
If materials with low dielectric loss tangent are used for GHz applications, then dielectric performance is improved, but mechanical strength and toughness decrease and cannot withstand handling during production
Solution Approach 1:
The patent creates a composite where continuous silica fibers are embedded in a polymer matrix. The polymer provides the low dielectric loss tangent required for GHz performance, while the silica fibers provide the mechanical strength and toughness needed to withstand handling during PCB production and post-processing operations.
Solution Approach 2:
The patent applies different material properties to different components of the composite: the polymer matrix is optimized for low dielectric loss to handle electromagnetic signals at GHz frequencies, while the silica fibers are optimized for mechanical strength and dimensional stability to provide structural support and withstand mechanical handling.
3Loss of energy
If continuous silica fibers are longitudinally co-aligned in a monolayer, then dielectric loss tangent is reduced to ≤0.0015 at 15 GHz, but manufacturing complexity increases
Solution Approach 1:
The patent employs a preliminary action by pre-aligning the continuous silica fibers in a monolayer configuration before embedding them in the polymer matrix. This pre-alignment ensures the fibers are properly oriented to achieve the required low dielectric loss tangent while simplifying the subsequent manufacturing process compared to attempting to align fibers after polymerization.
Data Source
AI summary
A printed circuit board (PCB) composite material includes a polymer layer and a fiber layer encapsulated within the polymer layer. The fiber layer includes a first monolayer of continuous silica fibers longitudinally co-aligned in a first direction. Each continuous silica fiber in the first monolayer extends without discontinuity through the polymer layer such that opposed ends of each continuous silica fiber are adjacent to a perimeter of the polymer layer. The PCB composite material has a dielectric loss tangent of less than or equal to about 0.0015 at 15 GHz or higher frequency. A printed circuit board (PCB) includes the PCB composite material and at least one conductive layer disposed on a side of the PCB composite material.