Cryo encompasses many different applications from Quantum Computing to Medical, from Defence and Aerospace to Test & Measurement, Science and Space.
Intelliconnect through its CryoCoax brand are a leading manufacturer and supplier of Cryogenic products in the USA, Europe and Far East. Products include cable, cable assemblies, attenuators, adaptors and connectors, including our award winning solderless connector series and unique high density connectors as well as a range of non-magnetic connectors and adaptors.
Case Study:
Cable and Connector systems for milli-Kelvin dilution fridges.
Background
Dilution refrigerators are routinely used to provide sub-Kelvin temperatures for quantum physics research, there is also a growing use in quantum computing applications. For many of these applications coaxial cables are used to connect the control electronics at room temperature to devices at the lowest temperature stage of the dilution refrigerator.
The coaxial cables are commonly incorporated into modular inserts sometimes known as ‘coax sticks’ or ‘coax trees’. These inserts help with customisation of the dilution refrigerator and often use cables of different materials at the various temperature stages. Cable having Niobium Titanium conductors is a popular choice at the low temperature stages to take advantage of its superconducting properties.
Our customer required us to develop process, procedures, supply chains and test regimes to manufacture their ‘sticks’.
Brief
Produce tooling for cutting, stripping, termination, forming, stick assembly.
Develop a suitable process to terminate all cable types including Niobium-Titanium.
Agree criteria for RF testing.
Provide suitable packaging.
Challenges & Solutions
Providing reliable connections and predictable RF performance can be a challenge, particularly with some of the exotic materials which we were required to use. The conventional method of terminating semi rigid cables is to solder the connectors, however Niobium-Titanium is very difficult to solder. Solder joints can also present issues at sub-kelvin temperatures. We first of all tried ultra-sonic soldering which, despite a significant outlay on equipment, failed to work! After looking at several options our design team developed a clever crimp/clamp solution which, while achieving similar electrical performance (Insertion loss/VSWR), removed to need for soldering altogether.
Another challenge was that due to the extremely high cost of these exotic and fragile cables, it was essential to minimise waste in the production process. We spent a huge amount of time effort and money in developing techniques and tooling in order to reduce process waste.
Transportation was another issue. With a product which potentially was 2m long with a multitude of layers of multiple cables, we were dealing with something both large, unwieldy and incredibly delicate. With the help of our packaging suppliers, we engineered a special packaging solution involving bespoke foam inserts and ribbed tubing which has successfully overcome the issue.
Outcome
Our customer is now established and happily receiving defect-free product for the past 5 years.