3D Interconnect Structure for RF Circuits
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Solution Overview
Problem
High-frequency RF, μWave, or mmWave systems face challenges in providing low loss, good RF matching, and high isolation on printed circuit boards, particularly above 20 GHz, due to the need for different technologies for various components and the increased size, weight, and cost of assemblies with machined lids for shielding.
Innovation Solution
A three-dimensional interconnect structure with coaxial conductors filled with a solid dielectric medium, incorporating shielded chambers for circuit elements, and using a mixture of metal structures with a dielectric medium to achieve impedance matching and reduce radiation losses, while minimizing size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If components are placed inside cavities with machined lids for high isolation, then isolation is improved, but size, weight and cost increase significantly
Solution Approach 1:
The patent merges the shielding function with the cavity structure by integrating shielding walls directly into the PCB layers. The ground planes and shielding structures are combined with the circuit board layers, eliminating the need for separate machined cavity lids. This integration maintains high isolation while significantly reducing weight and cost.
Solution Approach 2:
The patent replaces the mechanical machining process (machined lids) with a PCB fabrication-based shielding approach. Instead of mechanically machining separate cavity lids, the shielding is achieved through printed circuit board layers with ground planes and shielding structures that are part of the standard PCB manufacturing process.
2Reliability
If components are placed inside cavities with machined lids for high isolation, then isolation is improved, but size increases significantly
Solution Approach 1:
The patent merges the shielding function with the cavity structure by integrating shielding walls directly into the PCB layers. The ground planes and shielding structures are combined with the circuit board layers, eliminating the need for separate machined cavity lids. This integration maintains high isolation while significantly reducing weight and cost.
Solution Approach 2:
The patent transitions from a three-dimensional machined cavity structure to a planar PCB-based shielding approach. The shielding is achieved through layered PCB structures with ground planes and shielding walls that are integrated into the board layers, effectively using the PCB's inherent three-dimensional layer structure to provide the same isolation function with reduced overall size.
3Ease of manufacture
If traditional PCB technologies are used for high frequency RF above 20 GHz, then manufacturing is simplified, but loss and impedance matching deteriorate
Solution Approach 1:
The patent changes the physical parameters of the PCB structure by using thicker substrate materials (0.048 to 0.064 inches) and adjusting the dielectric properties to optimize for high-frequency operation. These parameter changes reduce RF loss and improve impedance matching while maintaining compatibility with standard PCB manufacturing processes.
Solution Approach 2:
The patent employs composite material structures combining different dielectric materials with specific electrical properties optimized for RF operation. The PCB uses a substrate with controlled impedance characteristics and complementary metal strip lines that create a composite transmission line structure, reducing RF loss and improving signal integrity at frequencies above 20 GHz.
4Adaptability or versatility
If custom ICs are developed for hybrid microcircuits, then system integration is improved, but development cycle time and cost increase
Solution Approach 1:
The patent segments the system into modular components that can be independently designed and assembled. The hybrid microcircuit approach allows different components to be produced in separate technologies and then assembled on a PCB substrate, enabling parallel development and reducing the overall development cycle time compared to custom monolithic ICs.
Solution Approach 2:
The patent creates a universal PCB platform that can accommodate multiple different components and technologies. The standardized PCB design with integrated shielding and RF-optimized structures serves as a multi-functional base that can support various RF components, reducing the need for custom development for each application and lowering overall development costs.
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 solution provides effective impedance matching, reduces radiation losses, and eliminates the need for external shielding cavities, resulting in a more compact, cost-effective, and efficient high-frequency circuit assembly.
Implementation Method 1
The first coaxial conductor is filled with a solid dielectric medium. The shielded chamber is filled with the solid dielectric medium.
Implementation Method 2
The solution provides effective impedance matching, reduces radiation losses
Data Source
AI summary
A three-dimensional interconnect structure having a top surface, a first coaxial conductor, and a shielded chamber is disclosed. The first coaxial conductor is filled with a solid dielectric medium. The first coaxial conductor has a segment that runs parallel to the top surface and a segment connects the first coaxial conductor to the top surface. Conductive pads on the top surface are adapted to receive a signal and couple that signal to the first coaxial conductor at the top surface. The shielded chamber contains a device connecting two conductors that are part of the three-dimensional interconnect structure to one another in that chamber. The shielded chamber is filled with the solid dielectric medium. The structure is a solid block composed of a mixture of metal structures interspersed with the solid dielectric medium.