Dielectric substrate and method of forming the same
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Solution Overview
Problem
Existing copper-clad laminates (CCLs) used in printed circuit boards (PCBs) face challenges in maintaining thermomechanical stability, electrical signal speed, and resistance to high temperatures and moisture absorption, which affect their performance in high-frequency applications.
Innovation Solution
A dielectric substrate comprising a fluoropolymer-based adhesive layer, a polyimide layer, and a filled polymer layer with a ceramic filler component having a mean particle size of at most 10 microns, which is integrated into copper-clad laminates and PCBs to enhance thermal stability and reduce electrical signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric materials are used in copper-clad laminates, then manufacturing is simpler and cost is lower, but thermomechanical stability deteriorates and electrical signal loss increases at high frequencies
Solution Approach 1:
The patent employs a composite dielectric layer comprising a fluorinated polymer matrix combined with ceramic particles (such as alumina, silica, or titania). This composite structure integrates the low dielectric constant and high thermal stability of fluorinated polymers with the high dielectric strength and thermal conductivity of ceramic fillers, achieving superior thermomechanical stability and reduced electrical signal loss while maintaining manufacturing feasibility through established lamination processes
2Speed
If the dielectric constant of the dielectric layer is reduced to increase signal speed, then electrical signal speed improves, but moisture absorption resistance deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the dielectric material by incorporating fluorinated polymers with specific molecular structures (such as PTFE, PFA, or FEP) that inherently possess low dielectric constants (2.0-2.6) and exceptional moisture resistance. The fluorine atoms create strong C-F bonds that are hydrophobic and chemically inert, simultaneously achieving high signal speed through low permittivity while preventing moisture absorption that would otherwise increase the dielectric constant and degrade performance
3Temperature
If conventional polymers are used in the dielectric layer, then manufacturing is easier, but resistance to high temperatures and dramatic temperature fluctuations deteriorates
Solution Approach 1:
The patent utilizes the thermal processing characteristics of fluorinated polymers, which exhibit controlled phase transitions during curing. The resin composition includes fluorinated polymer prepolymers that can be processed at elevated temperatures (up to 200-250°C) during lamination, then undergo controlled crosslinking or crystallization to achieve a stable, high-temperature-resistant network structure. This allows the dielectric layer to withstand soldering temperatures and thermal cycling while maintaining dimensional stability and electrical properties
Solution Approach 2:
The integration of ceramic particles (alumina, silica, titania) into the fluorinated polymer matrix creates a composite with enhanced thermal stability. The ceramic fillers have high melting points and low thermal expansion coefficients that match the polymer matrix, providing dimensional stability during temperature fluctuations. The composite structure also improves heat dissipation while maintaining ease of manufacture through conventional lamination and curing processes
Data Source
AI summary
The present disclosure relates to a dielectric substrate that may include a first fluoropolymer based adhesive layer, a polyimide layer overlying the fluoropolymer based adhesive layer, and a first filled polymer layer overlying the polyimide layer. The first filled polymer layer may include a resin matrix component, and a first ceramic filler component. The first ceramic filler component may include a first filler material. The first filler material may further have a mean particle size of at not greater than about 10 microns.