Flexible Vacuum Feedthrough Wiring With Thermal Break and RF Shielding
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Solution Overview
Problem
Existing cryostat systems face challenges in efficiently transmitting electrical signals and power across the vacuum-sealed interface between the cold, low-pressure region and the outside environment while maintaining thermal isolation and minimizing heat transfer.
Innovation Solution
The development of trans-vacuum flexible wiring apparatus using multilayer printed circuits with electromagnetic shielding and annular sealing regions, which includes a mesh pattern for RF shielding and a thermal break to manage thermal conductivity and electrical conductivity effectively, allowing for efficient signal transmission and power delivery while maintaining vacuum integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used to transmit electronic signals, then electrical conductivity is improved, but thermal conductivity increases causing heat transfer from room temperature to cryogenic region
Solution Approach 1:
The wiring apparatus is divided into multiple discrete wiring elements (individual traces) rather than using solid copper. This segmentation allows electrical conductivity to be maintained through the network of traces while reducing thermal conductivity by removing the continuous thermal path that solid copper would provide.
Solution Approach 2:
Different regions of the wiring apparatus have different properties: the wiring traces provide electrical conductivity where needed, while the spaces between traces and the support structure provide thermal isolation. The mesh pattern creates local variations in density and conductivity to balance electrical and thermal requirements.
2Object-affected harmful factors
If electromagnetic shielding is provided using solid copper layers, then RF shielding effectiveness is improved, but thermal conductivity and flexibility are compromised
Solution Approach 1:
The electromagnetic shielding is implemented using a mesh pattern rather than solid copper layers. This porous structure provides RF shielding effectiveness by blocking electromagnetic fields while allowing the flexible substrate to bend and flex. The mesh geometry can be optimized to provide adequate shielding at specific frequencies while maintaining flexibility.
Solution Approach 2:
The wiring apparatus uses a composite structure combining conductive traces, mesh shielding layers, and flexible substrate materials. This composite construction integrates electromagnetic shielding functionality with mechanical flexibility, allowing the apparatus to provide both RF shielding and the required flexibility for cryogenic applications.
3Reliability
If a vacuum seal is provided at the interface between air side and vacuum side, then vacuum integrity is maintained, but heat transfer through the seal region increases
Solution Approach 1:
The wiring apparatus acts as an intermediary element that crosses the vacuum interface. By routing electrical traces through the seal region rather than using separate feedthroughs, the apparatus provides both vacuum sealing and electrical connectivity. The trace geometry can be optimized to minimize thermal conduction through the seal while maintaining vacuum integrity.
4Adaptability or versatility
If multiple wiring elements are used to cross the vacuum interface, then electrical signal transmission is enabled, but manufacturing consistency and assembly reliability become difficult to maintain
Solution Approach 1:
Multiple wiring elements are merged into a single integrated flexible printed circuit apparatus. This consolidation ensures that all wiring elements are manufactured together as one unit, guaranteeing consistent spacing, alignment, and electrical properties. The integrated structure eliminates assembly variations that would occur if multiple separate wires or cables were manually positioned and connected.
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
This solution enables effective electromagnetic shielding, minimizes thermal conductivity, and reduces energy loss by using two flex cables with a thermal break, allowing for reliable and efficient transmission of signals and power across the vacuum interface with minimal thermal conductivity and energy loss.
Implementation Method 1
a flat laminated flexible material having an annular shaped sealing region able to be vacuum sealed between a cover plate and a perimeter of a hole in a vacuum chamber
Implementation Method 2
The two outer layers serve as electromagnetic shields while the two inner layers comprise the signal lines which typically require electromagnetic shielding
Implementation Method 3
The wiring apparatus also functions to balance electrical resistance with the thermal conductivity of the power and signal conductors
Data Source
AI summary
A novel and useful system wiring apparatus and related techniques that address the need to feed power and electronic signals to and from a sample board between the cold, low pressure region in a vacuum chamber and outside room temperature and atmospheric pressure. The wiring apparatus balances electrical resistance with the thermal conductivity of the power and signal conductors. Printed flexible cables are used having an annular sealing region which together with O-rings provide vacuum sealing while allowing electrical signals to pass between integrated circuit(s) inside the vacuum chamber and equipment outside the chamber. A thermal anchor is placed along the printed flexible cable to maintain a desired temperature along the cable. The printed flexible circuits are multilayer with two outer layers serving as an RF shield while two inner layers comprise the signal lines which typically require shielding, electrical isolation from each other and from external electromagnetic fields.