Ceramic RF Feedthrough With Non-Ferrous Conductors for Low PIM
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Solution Overview
Problem
Glass-to-metal feedthrough components in hermetically sealed electrical circuit packages are laborious and costly to manufacture, and they suffer from poor RF conductivity and passive intermodulation (PIM) distortion due to the lossy nature of materials like nickel and Kovar, which attenuate RF signals and cause interference.
Innovation Solution
The use of non-ferrous conductors, such as silver or palladium, adhered to a ceramic body using thick-film or thin-film technology, with voids to accommodate thermal expansion, and a hermetic seal formed by non-leaching solder, reduces manufacturing complexity and improves RF conductivity and reduces PIM distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass-to-metal feedthrough components are used, then hermetic sealing is achieved, but RF conductivity deteriorates due to lossy materials like nickel and Kovar
Solution Approach 1:
The patent changes the material parameters by replacing ferrous materials (Kovar, nickel) with non-ferrous materials (copper, beryllium copper, beryllium) that have superior RF conductivity and lower loss characteristics, while maintaining the hermetic sealing function through alternative design approaches
Solution Approach 2:
The patent employs composite material structures combining non-ferrous conductive materials with ceramic or glass insulators, creating a feedthrough component that achieves both hermetic sealing and improved RF conductivity through the synergistic properties of different materials
2Reliability
If traditional glass-to-metal feedthrough manufacturing is used, then hermetic seal is formed, but manufacturing complexity increases due to laborious assembly processes
Solution Approach 1:
The patent merges the sealing and conducting functions into an integrated non-ferrous conductor structure that is hermetically sealed directly to the ceramic body, eliminating the need for separate ferrule and plating assemblies, thereby simplifying the manufacturing process
Solution Approach 2:
The patent extracts the problematic ferrous materials (nickel, Kovar) from the feedthrough structure and replaces them with non-ferrous alternatives, removing the source of RF losses and manufacturing complexities associated with traditional glass-to-metal bonding processes
3Reliability
If Kovar pin with nickel plating is used, then corrosion resistance is achieved, but PIM distortion increases due to ferrous material properties
Solution Approach 1:
The patent changes the material composition from ferrous (Kovar, nickel) to non-ferrous materials (copper, beryllium copper) that inherently provide both corrosion resistance and low PIM distortion characteristics, eliminating the harmful ferrous material properties
Solution Approach 2:
The patent replaces expensive, complex multi-layer plated ferrous structures with simpler, more cost-effective non-ferrous conductor designs that achieve the same or better performance in terms of corrosion resistance and RF performance
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
Ceramic RF feedthroughs with non-ferrous conductors offer improved RF conductivity, reduced attenuation, and lower PIM distortion, resulting in cost-effective and efficient performance compared to traditional glass-to-metal feedthroughs.
Implementation Method 1
The non-ferrous conductor is selectively adhered to an outer peripheral surface of a ceramic body and to an inner peripheral surface of an aperture through the ceramic body. A non-ferrous conductive lead is disposed through the aperture... with voids to accommodate thermal expansion
Implementation Method 2
The use of non-ferrous conductors, such as silver or palladium, adhered to a ceramic body using thick-film or thin-film technology
Implementation Method 3
The use of non-ferrous conductors, such as silver or palladium, adhered to a ceramic body using thick-film or thin-film technology
Implementation Method 4
The hermetic seal is necessary to prevent infiltration of fluids, particulates and other environmental contaminants
Implementation Method 5
The non-ferrous conductor selectively adhered to an outer peripheral surface of a ceramic body... offers improved RF conductivity, reduced attenuation, and lower PIM distortion
Data Source
AI summary
A radio frequency (RF) feedthrough component having an impedance greater than 20 ohms is disclosed. The feedthrough includes a ceramic body having a flexible non-ferrous conductor adhered to its outer peripheral surface and to an inner peripheral surface of an aperture through the ceramic body. A non-ferrous conductive lead is disposed through the aperture and protrudes from at least one side thereof. A non-ferrous hermetic seal is formed between a portion of the non-ferrous conductive lead disposed in the aperture and the non-ferrous conductor adhered to the surface of the aperture. The RF feedthrough can be assembled in an opening of a conductive housing to form an electromagnetically shielded package for an electrical circuit.