CCTS Features & Benefits
- Lowest Mass Thermal Strap Product Commercially-Available (End Fitting Mass is 33% less than Al 6061)
- Highly Flexible (GraFlex III woven sheet products offer unique flexibility and durability attributes, different from our GraFlex I and II bundle, and graphite/graphene sheet straps)
- Highly efficient and thermally conductive (2x-5x as thermally conductive as metallic straps)
- Unmatched vibration attenuation/damping
- 1/4th-1/15th the mass of equivalent copper and aluminum strap assemblies (on average)
- High conductance to low interface area ratio: end fittings/terminal blocks are a fraction of the mass and size of those of metallic straps
Graphite Woven Sheet or Bundles/Rope
TAI builds our CCTS assemblies using our GraFlex I and II bundles, GraFlex III weave/sheet material (made from graphite fiber with thermal conductivity over 800 W/m-K), pyrolytic graphite sheets (1,500 - 2,000 W/(m-K)), or graphene composite (1,500 W/(m-K)) sheets (come back for pictures of our stacked graphene composite and pyrolytic graphite sheet CCTS assemblies, coming spring of 2017).
GraFlex III Woven Sheets
GraFlex III in under development by our sister company, TAI, Inc. (which specializes in thermal strap R&D programs and developing new strap and thermal management technologies). This new material utilizes a proprietary, high conductance graphite that is woven into a highly flexible cloth/sheet material. Sheets are available in standard 1", 2" and 3" widths.
GraFlex III is more flexible than I and II on the compression axis, and also offers other unique flexibility attributes. Unlike foil, PGS or graphene composite sheet straps, it also offers flexibility on the horizontal / Y axis. This thin, low profile material is ideal for electronics box applications with limited volumes that often rule out a traditional GFTS™ or CuTS™ solution. GraFlex III, while having lower thermal conductivity, is also far more durable than PGS or graphene composite sheet straps. While (theoretically), pyrolytic graphite and graphene composite sheets should be extremely strong ("as strong as diamond, as material manufacturers often claim); the reality (that most at NASA and in the aerospace world can attest to), is that PGS and graphene composite sheets and films are incredibly delicate and fragile. As a result, simple mishandling during transportation, testing and installation, can catastrophically damage PGS and graphene straps (let alone the typical vibration and shock profiles straps are subject to during qualification and launch).
While there are some limited cases where a PGS or graphene composite strap may be ideal (where flexibility on all 3 axis is not important, and thermal conductance requirements cannot be met using copper or GraFlex), and TAI does produce PGS and graphene compsoite straps for these cases, it is important to note to our customers that neither PGS nor graphene sheet straps have space flight heritage, and their durability concerns are a serious concern which must be weighed when choosing your strap.
GraFlex I and II
Each GraFlex bundle consists of thousands of individual carbon fibers wrapped with a special polyester cord for support. Our GraFlex II bundles offer higher conductance, as they have twice the number of fibers per bundle, and a 100% larger diameter. These graphite fibers have 2.75 times the thermal conductivity of copper at room temperature and one quarter of the density. Therefore, on a thermal conductivity/mass basis, they are eleven times more weight efficient than copper, and over six times more weight efficient than aluminum. Our proprietary CCTS fabrication process realizes up to 95% of the material thermal conductivity while providing a metal interface configuration for bolting the strap between the heat source and sink. The graph below shows the temperature dependent thermal conductivity of the graphite fiber in comparison with other typical thermal strap materials.
End Fittings / Terminal Blocks
Our CCTS end fittings / terminal blocks are made of aerospace grade, proprietary carbon fiber composite material, and GraFlex is bonded into the end fittings with our Condux epoxy. The table below compares material specs of our carbon composite end fittings and that of aluminum 6061 and cu 10100:
Graphite (GraFlex I, II, III) Thermal Conductivity vs Al and Cu