Cabled Copper Thermal Straps (CuTS®)
Cabled Copper Thermal Straps (CuTS®), also referred to as "heat straps," "S-links," or "flexible thermal links," are the most durable and affordable thermal strap available. CuTS® are made using only OFHC copper and fabricated using TAI's unique cold press assembly process. The solderless, heat-free process, refined over decades and tens of thousands of straps, optimizes flexibility and minimizes contact resistance losses, resulting in a highly-efficient link, ideal for thermally-conductive vibration isolation at nearly any operating temperature. This combination of quality and efficiency makes CuTS® ideal for numerous applications in the aerospace, superconductor, semiconductor, and cryogenic engineering industries.
Beyond their unrivaled quality, dependability, and thermal performance, several key factors make CuTS® unique:
In-House Manufacturing: experienced technicians assemble all of our thermal straps on-site, and we never outsource our products to third-party machine shops. In-house fabrication ensures strict quality control, the lowest prices in the industry, and allows TAI to guarantee our products with a one year warranty.
Assembly Method: TAI uses a unique swage process and post-assembly machining method to manufacture our copper thermal straps. We never weld, braze, or solder our straps.
Cable Flexibility: CuTS® use TAI's OFHC UltraFlex® I & II copper cabling.
Standard and Custom Designs: CuTS® are available in custom, and 100+ standard models.
Plating Options: Copper and aluminum-copper hybrid CuTS® are available with nickel and gold plating options exclusively offered by TAI.
Spaceflight Heritage: CuTS® have extensive flight heritage on satellites and commercial crew and cargo vehicles.
Experience: The TAI team has a combined total of 57 years of strap design, manufacturing, and qualification experience, and has designed and delivered more straps than any organization on the planet.
Manufacturing Capacity - TAI is the only supplier with the equipment, facilities, and technical, administrative, and manufacturing staff required to fill production orders (and we have the track record to prove it).
Whether you need a single thermal strap for a dewar, focal plane, or cryocooler, or tens of thousands of units for cold boxes or military optical systems, you can count on the experts at TAI. To learn more about TAI's thermal strap products, conductivity, and applications, download our handout: Thermal Straps - Performance, Pricing, and Product Options. Be sure to also request your copy of our CuTS® Catalog below.
Visit our CuTS® Design Galleries to See Hundreds More!
*Unlike some "suppliers," TAI does not post stolen or edited images in an attempt to misrepresent our design, production, or plating capabilities, spaceflight heritage, or program history.
TAI is the only supplier that offers a fully-customizable standard line of thermal strap products, and each year we release our annual edition of the CuTS® Catalog. Our CuTS® Catalog now features 120 Standard Models (though roughly half of the straps we manufacture are completely custom), and copies are available by request. Our standard line is comprised of our Standard and Cryocooler Series models, and the catalog outlines customization options in addition to performance and mass projections for each model (and at multiple operating temperatures).
While Standard and Cryocooler Series CuTS® provide customers with the most affordable option and shortest lead times, custom units typically cost the same (on a per-unit basis) but require an additional week for design and fixturing. To learn more about our standard and custom strap offerings, request a CuTS® Catalog.
Pictured: P6-503 CuTS® Units - Counterbored Bolt Holes and TAI Standard OFHC cu Braid
Pictured: CS-68B (Cryocooler Series CuTS®) with OFHC UltraFlex™ Cabling
Pictured: Custom CuTS® - Pulse Tube Cold Head Adapter Ring and OFHC UltraFlex™ Cabling
Superior Thermal Performance
TAI's Copper Thermal Straps are fabricated using only high purity, OFHC copper cabling and fittings. This 99.99 - 99.998% pure copper, combined with our unique cold press assembly process, make CuTS® the most efficient copper straps commercially-available, and ideal for use across a wide temperature range (CuTS® have been qualified at temperatures from 100mK - 873K).
Determining the thermal performance of a strap at a given operating temperature requires more than just a knowledge of the material purity, though. The residual resistivity ratio (RRR) of the copper (in the assembly as a whole), will more accurately represent the thermal conductivity at cryogenic temperatures than the material purity alone (OFHC copper typically has a RRR between 50 - 150). To learn more about the RRR of OFHC copper and other materials, visit NIST's Cryogenic Material Properties Page, here.
Fortunately, TAI's copper thermal straps have been extensively tested (on the assembly level), by researchers at numerous US National Laboratories, and have produced a consistent RRR of 75 - 100+. Should your application require additional thermal performance, CuTS® can always be vacuum annealed or e-beam welded to increase RRR (TAI does not perform these services at our facility).
However, superior performance is more than just materials; it is predictability, consistency, and the ability to provide accurate conductance projections at any temperature for any design. This requires extensive testing, and the design, manufacture, and qualification of thousands of copper thermal straps. Our experience and strict quality control allows TAI to continuously refine our projection software and capabilities, and enables our experts to provide highly-accurate performance projections from 1K, to over 800K, accounting for contact resistance losses at the heat sink and source interfaces, and various thermal interface materials including eGraf, Sigraflex, or Indium foils.
Pictured (top left): Historical NBS measurements of copper thermal conductivity.
Thermal Strap Conductivity Calculator
New for 2020, TAI customers (and engineers that have downloaded our 2020 CuTS® Catalog), can now use our CuTS® Conductivity Calculator app to calculate the thermal conductivity of many of our standard models at various rope lengths. To learn more about our standard models and use the app, request a copy of our new catalog, or contact our Director of Business Development (if you are a previous customer).
More models, product calculators, and calculator options are coming throughout 2020, so be sure to bookmark this page today, and come back and visit our Graphite Fiber, and X-Series® Thermal Strap Pages.
OFHC UltraFlex™ I & II Copper Cabling
OFHC UltraFlex™ I is our 0.10" diameter cabling. It was developed by our engineers in 2016, is only available from TAI, and is specifically designed to provide increased flexibility, while maintaining the same diameter and thermal performance of our previous TAI Standard OFHC copper braid. CuTS® assemblies made with OFHC UltraFlex™ cabling offer >65% flexibility on the compression axis (X), and average >25% flexibility on the Y and Z axes than other commercial straps and shunts using braided (flat and rope) materials. Though our team has extensive experience with multiple cable and braid types, all of our custom and standard CuTS® come standard with our OFHC UltraFlex™ I and II Copper Cabling.
OFHC UltraFlex™ II is our 0.20" diameter copper cabling and is used in custom and standard models. UltraFlex II is unique in the industry, is only available from TAI, and is the industry's most flexible 0.20" diameter cabling. This cabling is ideal for customers with larger heat dissipation needs with the available volume to accommodate thicker end fittings.
In addition to US National Laboratory thermal conductance qualification in the mK and 1K - 10K range, TAI's CuTS® products have successfully passed several life cycle flex tests, of up to 1 Million flex cycles on the compression axis. To view videos of the life cycle flex tests, click here now.
Pictured (Bottom): TAI CuTS® Models P60-501 and P60-502, using our exclusive OFHC UltraFlex™ II (July 2019).
Aluminum End Fittings (Hybrid Copper Thermal Straps)
Aluminum end fittings are available on all of our standard and custom CuTS® products. Aluminum fittings are 70% lighter than their copper counterparts and have a negligible impact on thermal performance. This option is available at no additional cost, and our expert technicians can also directly integrate our OFHC UltraFlex I and II Cabling into aluminum cold plates, adapter/extension brackets, and other components.
Pictured: Custom CuTS® with Al 6061 fittings; SUrface Dust Analyzer instrument on the Europa Clipper Mission (March 2019).
Gold & Nickel Plated CuTS®
CuTS® are available with gold and nickel-plating options exclusive to TAI. For customers requiring gold plating, we offer multiple diffusion barrier options (both magnetic and non-magnetic), and straps can be plated to certain ASTM standards (B-488 Type I & III, Code C & D, for example). However, our two most popular gold plating options are TAI's "Lab Grade" (99.7% pure gold, non-magnetic diffusion barrier), and our "NASA Grade" (99.99% pure, "hard gold" plating, with a Knoop Hardness of 180, and electroless ni diffusion barrier). Plating does increase unit cost and lead time by 1 - 2 weeks (depending on plating type); so plan accordingly.
TAI designs, assembles, plates, and cleans our thermal straps using proprietary methods (developed by our experts), so that each assembly is as clean as possible. While customers consider them UHV-compatible/ready, we recommend a vacuum bake-out prior to installation in UHV and optical applications (as we cannot guarantee cleanliness to a specific spec). RGA Spectra analysis proves TAI's plated straps are as clean as non-plated CuTS® that are ultrasonically cleaned and subjected to a standard vacuum bake out (24 hours at 150C).
LAB GRADE Gold Plating - JANIS ST-400 Cryostat
LAB GRADE Gold Plating
Electroless Nickel (High Phosporus)
Using our plating technique, there is virtually no measurable impact to flexibility/stiffness of the copper cables.
Pictured (Top Left): P6-501 units with Nickel and Gold Plating, Post-Bake out and RGA Spectra Analysis (August 2017).
Gold & Nickel-Plated Al-Cu Hybrid Thermal Straps
Developed in 2019 and exclusively offered by TAI, our experts now provide the world's only nickel and gold plated Al-Cu hybrid thermal links. Previously, it was only possible to plate straps made entirely of copper OR aluminum ropes and foils, due to the chemicals and processes required with traditional metallization/plating. Now, customers requiring the corrosion protection of electroless nickel or gold, and the thermal performance of OFHC copper cables, can have the added benefit of lightweight aluminum end fittings (reducing overall assembly mass as much as ~60%, depending on rope length); making Al-Cu hybrid straps an attractive option for many spaceflight and airborne systems for defense and commercial applications.
|P5-502 Al-Cu Hybrid Strap (June 2019)||P5-502 Al-Cu Hybrid with Electroless Nickel Plating (August 2019)|
Gold Plating Thermal Straps for Cryogenic Applications
Contact resistance at cryogenic temperatures affects a large number of important terrestrial and spaceflight applications. These include space-based detectors, ground-based dark matter and dark energy experiments, electronic packaging of superconducting circuits, and most cryogen-free systems which are conductively cooled via cryocoolers. Additionally, engineers working with dilution refrigerators, cryostats, and cold boxes are often equally-sensitive to thermal contact resistance losses, and in need of a means improve efficiency.
Poor thermal contact can lead to longer cool-down times, poor thermal equilibrium between samples and the cooler, and large temperature gradients across the contact for small heat flows during operation. These problems become more severe as operating temperature decreases, thus, the need for gold plating increases.
Due to its low oxygen affinity, gold plating of copper fittings and cables is a highly effective solution to prevent oxidation and achieve electronic thermal conductance across interfaces. Additionally, surface oxide of gold breaks at a low applied load, thereby giving a larger probability of achieving a metallic contact. Gold also has a lower surface hardness than copper, and as a result, gold plated contacts have a larger area of physical contact, and therefore, lower thermal resistance for a given applied force. Gold plating also is used to minimize the absorption of radiant heat, and TAI's gold plating options offer the lowest surface emittance in the industry.
Pictured (Top Right): NASA GRADE Gold Plating CuTS®.
Content Credit: Ram Dhuley, FNAL, "Pressed copper and gold-plated copper contacts at low temperatures – A review of thermal contact resistance"
CuTS® Spaceflight Heritage
The list below details just a handful of the missions our CuTS® products have flown, or will be launching on, shortly:
Lockheed Martin/NOAA's GOES-R - Launched November 2016
NASA's OSIRIS REx - Launched September 2016
Numerous Department of Defense Satellites (Program Names Withheld) - Launched 2016 - 2018, scheduled for launch 2019 - 2022
NOAA's GOES-S/T/U - Launched 2017 - 2018 and beyond
NASA JPL's GRACE-FO - Launched 2018
Orbital ATK's Cignus OA-9 Spacecraft - Launched May 2018
NASA's GEDI Sensor (on board the ISS) - Launched December 2018
Eumetsat's METEOSAT - Launches 2020
NASA JPL's Deep Space Atomic Clock (DSAC) - June 22, 2019
ESA's Solar Orbiter - Launches February 2020
In 2016 - 2019, TAI provided over 1,500 prototype, "proto-flight," and FM CuTS® assemblies for numerous space programs (and for nearly all commercial crew/manned spacecraft programs). Our customers include: Lockheed, NASA, Ball, Airbus, OHB, Thales, L-3, Honeywell, Harris Corp., MIT, Orbital ATK, Surrey Satellite (SSTL), ABB, Micos, and many others.
Pictured: NASA Engineer prepares the GEDI Sensor (complete with 9 CuTS®), for launch (Fall 2018).
CuTS® for University Research Programs
TAI offers unique partnership and support opportunities for our university (and some) national laboratory customers across the globe. From exclusive offers and reduced pricing of our CuTS® products, to complimentary thermal system design and manufacturing services for cutting-edge programs in the areas of physics, chemistry, and aerospace engineering, our team is happy to help!
Other Manufacturing & Integration Capabilities
Thermal straps provide mechanical decoupling and vibration damping in thermal systems which also incorporate vapor chambers and heat pipes. While our traditional approach is to design the ideal fittings (given your interfaces and attachment method), TAI can (in many cases), press our OFHC copper cabling directly into the structure of a cold plate, heat pipe, or vapor chamber (eliminating the end fittings entirely, thereby eliminating the additional joints and subsequent resistance losses).
TAI can design and manufacture various adapter blocks, brackets, clamps, cold plates, and other structural components as needed. These parts are made using a wide range of materials, though OFHC Cu and Al 6061 are the most common. While it may make sense for some customers to machine their components (as is the case with many of our university customers), TAI can often provide these components at a lower unit cost than if they were machined (internally) by most of our aerospace customers.
Pictured (Left): FM CuTS® With Adapter/Extension Arms - Parker Solar Probe, NASA. Pictured (Right): TAI's Flexible Vapor Chambers (integrated directly with OFHC UltraFlex™ Cu Cabling).
Outsourced vs. In-House Thermal Strap Manufacturing
There are several important questions to consider when ordering thermal links, given the substantial differences between in-house and outsourced manufacturing:
Will your thermal straps arrive damaged, unusable, or extremely dirty?
Is the supplier involved in each step of the process, or do they only place an order to a 3rd party machine shop?
- Are your thermals straps assembled by children, day laborers, or unskilled machine shop workers?
Has your supplier ever made this particular type of strap?
Has the supplier ever plated a thermal strap, or do they try to fool you by editing photos of bare copper units?
What quality, risk and cleanliness risks are these issues going to expose your program to?
Unfortunately, this is all too common an issue in our industry, and when a supplier has zero hands-on experience manufacturing the copper thermal straps they sell, no production facilities—nor production staff—this dramatically increases the risk of issues like:
Oils, cutting fluids, grease and other contaminants, and
Production Orders: when you need thousands, or tens of thousands of units (like many of our customers), it's important to ask other questions: "Do they have the necessary staff (technicians, engineers, and administrative personnel), and an actual manufacturing facility to fill my order?" Or, "Do they have a track record of production programs, and timely, successful deliveries?"
With TAI, no matter the application, quantity, or budget, your thermal straps will always be made to the same quality standards demanded by organizations like NASA, ESA, or Lockheed Martin, yet will be the most affordable thermal strap product on the market. TAI has provided (or is currently providing), production orders of hundreds and even thousands of straps, to customers from BAE Systems, to ASML, KLA, Fermi, Jefferson, and Argonne National Labs, and multiple technology and aerospace companies across the United States and Europe.
Thermal Strap Cleaning and Testing Services
After fabrication, all copper thermal straps are tested and then ultrasonically cleaned and bagged before shipping. TAI offers optional nitrogen purged bags for shipping your straps, but we also recommend that any thermal strap used in a UHV, sensitive optical, or space/satellite application, undergo any additional cleaning spec/procedure your organization requires for copper hardware. For example: some laboratory and aerospace customers will perform an additional round of ultrasonic cleaning in a bath of Alconox™, Citranox™, acetone, or various copper cleaners (and then perform a vacuum bake out), prior to installation. In rare cases (such as sensitive satellite optical systems), some customers may require their copper straps are cleaned to a specific spec. TAI does contract with a partnering test and cleaning facility to perform the cleaning in these cases.
TAI provides a comprehensive range of strap testing services to our clients (some of which are complimentary, and other services are offered at an affordable rate and performed either here at our facility, or by one of our internationally renowned testing facilities). Each assembly will pass quality checks and undergo thermal conductance testing after construction to verify requirements-compliance. TAI's Management, Engineers, and Program Managers have extensive experience with the Quality Assurance processes and qualification that is required by the industry's top primes, NASA, ESA, and JAXA.
Pictured (Above): Custom UHV Chamber CuTS® [Post-Polishing] (1/9/18). (Left): Custom FM CuTS® - ESA Solar Orbiter (February 2016).
CuTS® Flexibility Demonstrations & Stiffness Data
TAI also offers stiffness graphs taken from several custom and standard model copper thermal straps we've manufactured. While the data gathered is not a guarantee of performance in your own design (as stiffness is a function of the rope/cable/braid type, the rope length (RL), number of ropes and number of rows), it can provide you with a rough understanding of what to expect (in N/mm, on each axis).
Contact TAI for more information.