PGS & GRAPHENE THERMAL STRAPS
X-Series® | The World’s Highest Performance Straps
In recent years, the flexibility and thermal performance requirements demanded by certain spaceflight applications have reached unprecedented levels (particularly with ultra-fine pointing laser communication systems, optical systems, FPGA’s, and inside tightly-packaged electronics boxes). In some cases, these have effectively eliminated traditional metallic cable, foil, and graphite fiber straps as a solution. To meet these challenges, TAI offers our X-Series® product line; the world's highest thermal performance, "Zero-Stiffness" thermal straps.
X-Series® PGL™ and GTL™ straps are made with Pyrolytic Graphite Sheets (PGS), and are also available with Graphene Foil. When combined with our proprietary design and assembly methods, they are entirely unique in the industry, offering a number of important benefits over other strap types, including:
- 3 – 4X the performance of equivalent copper and graphite fiber straps
- 10 – 30% greater thermal performance than competing carbon straps
- PGS offers 6X the thermal performance of aluminum and 4X the performance of copper at room temp
- PGS and Graphene are both 28% lighter than aluminum, and 77% lighter than copper
- TAI's X-Series® PGS straps (PGL™) are the industry’s most flexible thermal straps
- X-Series® straps are exceptionally clean and passed strict PCL/PAC/FPAC testing
- X-Series® PGL™ straps are at NASA Technology Readiness Level (TRL) 8
Because of these many advantages, TAI's X-Series® are the ideal thermal straps for many space system and cubesat applications. However, while they offer superior thermal performance to our CuTS®, CuFS®, and GFTS® products, all forms of pyrolytic graphite sheet and graphene foil straps have their own limitations and trade-offs to consider. Our engineering and design team is here to help you understand these, and to identify the most efficient and affordable strap for your program.
Visit our New X-Series® Thermal Strap Design & Program Gallery
Custom and Standard Model (X-Series®) Straps
PGL™ and GTL™ products are made entirely of NASA approved, low/zero outgassing materials, and are offered in standard and custom configurations. X-Series® Links/Straps are our standard model line, and can be manufactured with either PGS film or Graphene foils (depending on customer preference and performance requirements). The X-Series® comes with 12 standard configurations (based on design and material), and multiple end fitting options.
All PGL™ and GTL™ products come with optional Mylar® or kapton encapsulation sleeves, and chromated end fittings for corrosion mitigation. Models in our new 2020 Catalog now offer even higher thermal performance, and both products have been qualified by engineers at NIST and medical engineering & instrument companies from 10K - 300K, and TAI can make highly accurate projections across this range.
To learn more about our standard and custom strap offerings, request your copy of the X-Series® Catalog.
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The World's Highest Thermal Performance
TAI's X-Series® products offer the highest thermal performance available in the industry; providing a material thermal conductivity of 1,600- 2,500 W/(m-K), depending on material, operating temperature, and sheet thickness (though graphene foil/sheet may one day offer even higher thermal performance than the current 1,700 W/(m-K) available in the industry, as the manufacturing technology improves). However, the materials used are just one aspect that makes our products unique. These materials, when combined with our proprietary design and assembly methods (which minimize resistance losses), result in unrivaled thermal performance.
Though these straps do not have years of spaceflight heritage (like our copper and graphite fiber thermal straps), they are a unique product, offering a particular set of benefits which make them ideal in volume-restricted applications like Xilinx™ electronics boxes, FPGA/chip & PCB cooling applications, and cubesats.
*It should be noted that we do not provide "monolayer graphene straps," as there are no (actual) monolayer graphene sheet thermal straps available in the industry. While a single layer of graphene can achieve a thermal conductivity in excess of 3,500 W/(m-K), it is only 0.35 nm thick.
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Specific Thermal Conductivity of Strap Materials
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Thermal Conductivity of Strap Materials
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NASA Spaceflight Qualification & Current Programs
TAI's X-Series® (PGL™) products were space-qualified by NASA JPL in 2018, and are now being used on multiple spaceflight programs in both Europe and the United States, by Airbus, Lockheed Martin, the DLR, CNES, Ball Aerospace, General Atomics, NASA, and the University of Hawaii-Honolulu, and are slated for use in spaceflight programs in 2021-2023 by NASA and others. Testing performed by TAI, NASA, and outside facilities included:
- Thermal Conductance
- Thermal Cycling
- Post-Thermal Cycling Thermal Conductance
- Stiffness
- Vibration
- Post-Vibration Thermal Conductance
- Particulation Contamination Level (PCL)
- Outgassing
- Post-Vibration PCL
This extensive qualification proved that TAI's X-Series® PGL™ products are the cleanest, most efficient, and most flexible carbon sheet strap on the market, and are durable enough to withstand extremely high vibration environments (while at the same time offering the highest thermal performance of any space-qualified strap in the industry). For test data, please contact us today (complete vibration, thermal conductance, stiffness, and PCL/PAC/FPAC reports are available).
 Pictured: X6-501 NASA Stiffness Test (October 2018). |
 Pictured: Dual X6-501 NASA Vibration Test (November 2018). |
PGL™ - The "Zero-Stiffness" Thermal Strap
Perhaps one of the most unique and exciting benefits of our X-Series® PGL™ products, is their inherent "low/zero stiffness" attribute (when assembled and encapsulated using TAI's proprietary process). Not only does the pyrolytic graphite sheet material used in our products offer superior flexibility to graphene foils and all other strap materials (as a film material, it is far more flexible and durable than graphene foils), but stiffness tests performed on our X6-501 PGL™ assemblies revealed stiffness measurements in the mN/mm range, and on all 3 axes when installed in curved or S-configurations (with many measurements ≤3mN/mm). As a result, our PGL™ products exceeded all expectations and came in well under the most restrictive stiffness requirements ever levied on a thermal strap in NASA's history (making PGL™ straps ideal for highly sensitive optical and photonics applications).
For more information and stiffness qualification data and graphs, contact us today.
Pictured (Right): X6-501 PGL in shipping fixture (October 2018).
X-Series® Program and Spaceflight Heritage
TAI will be adding details about our program and spaceflight heritage throughout 2019 and 2020, as QM and FM models are delivered to our customers at Lockheed Martin, Airbus, the DLR, NASA and more. Come back soon to learn more about the programs and applications our straps are a part of!
Our team will be adding pictures and test data from programs with customers from Lockheed Martin, to Airbus, the DLR, CNES, NASA JPL, and more, throughout the year. To learn more, contact us today!
Pictured: X-Series® PGL™ straps with mylar sleeves and adapter brackets; DLR / CNES (April 2019).
Which Carbon-Based Thermal Strap is Right for Me?
TAI offers multiple carbon-based strap products because no single configuration or material is ideal under all operational and environmental conditions.
Though they have a lower thermal performance, our Graphite Fiber-based straps are typically more durable and lighter than carbon sheet straps, and they do not need to be designed into C/U/S-shapes in order to flex on the lateral axis/provide lateral deflection (which is helpful for applications such as battery pack cooling, antenna arrays, optical instruments, and some deployable/moving/rotating instruments and equipment). Though spaceflight customers most commonly choose GraFlex I and II, GraFlex III is also ideal for applications with extremely limited volumes, but requiring flexibility on each axis.
Graphite/Graphene sheet straps are better-suited to applications with compact envelopes, requiring little to no flexibility/range of motion or repeated flex cycles (such as electronics boxes, chip cooling, etc.), or those with extremely low stiffness requirements. Because of their higher performance at lower temperatures, PGL™ products are now a superior replacement for aluminum foil thermal links at temperatures as low as 50K, and can be used in place of OFHC copper straps at temperatures as low as 70 - 80K (to reduce mass but offer similar thermal performance).
Pictured (Right): Custom PGL™ pre-thermal conductance test (May 2018).
Important Limitations To Consider With PGS & Graphene Foil
First and foremost: do not confuse "single/monolayer graphene," with "graphene sheets or foils," or be deceived by claims regarding the durability of pyrolytic graphite and graphene sheets. Straps can be torn if mishandled (these are not metallic cable or foil straps), flexed on the lateral axis (while not in a full C or U-shape, or in an S-shaped/curved installation configuration), or if the straps are meant to be a load bearing component in the system.It is also important to understand that despite any claim to the contrary, all carbon materials; graphite, pyrolytic graphite, and graphene sheets/films/foils, can pose particulation and contamination risks under certain circumstances, and will generate FOD if damaged. As a result, all carbon-based straps should be encapsulated (typically with an aluminized mylar sleeve, or "blanket"), if used in contamination/particulation-sensitive applications like optical and laser systems.
This does not mean that PGL™ and GTL™ products are not suitable for any application; only 
that they are ideal under certain circumstances, and environmental & operational conditions. Our experts will help you to determine which product best suits your operational environment and performance requirements, to ensure the success of your program.
that they are ideal under certain circumstances, and environmental & operational conditions. Our experts will help you to determine which product best suits your operational environment and performance requirements, to ensure the success of your program. Pictured (Top): All forms of graphite, pyrolytic graphite, and graphene foil/sheet present FOD & contamination risks (and must be encapsulated). (Bottom): First generation PGL/PGS thermal strap with tearing/mechanical failure due to improper handling during installation and removal from test fixture.
Graphene Foil and "Micro-Cracking"
While TAI has extensive experience designing and testing our graphene foil-based straps (and our PGL™ & GTL™ products have been tested by NIST researchers), our team will only recommend a graphene foil solution under very limited applications and operating environments.
As our customers and colleagues at NASA, NIST, the Indian Space Research Organization (ISRO), and the European Space Agency (ESA) have all noted and experienced firsthand (either with graphene foil thermal links / straps, or individual graphene foil sheets), one critical problem plagues all graphene foils and composite sheets: "micro-cracking" or stress fractures. These tiny cracks are caused by flexing/bending strap assemblies (or sheets), and even occur with the minimal movements associated with thermal expansion. These fractures can grow over time, and eventually lead to reduced performance, damaged foils, and compromised straps / links.
Further, tests performed by NIST researchers demonstrated that layered graphene foil-based thermal links experienced significant performance degradation after being thermally-cycled (just two additional cycles can result in conductance losses of >15% at 160K).
Graph: Graphene-based Thermal Links demonstrated a 10-15% drop (depending on operating temperature), in thermal conductance after two thermal cycles (February 2020).