ALUMINUM FOIL THERMAL STRAPS
Solderless Flexible Thermal Links
TAI no longer offers aluminum foil thermal straps, due to low customer demand, superior alternatives, and high manufacturing costs when compared with copper rope straps. While aluminum thermal straps/aluminum thermal links (AlTS) were beneficial in the past (in limited spaceflight applications operating between 40K - 80K), they have largely been replaced by TAI's CuTS® and PGL™ products. This is because our copper rope straps provide superior thermal performance, at a small fraction of the cost of aluminum foil links, and our pyrolytic graphite film links/straps (while slightly more expensive), offer superior thermal performance, at a fraction of the mass of an equivalent aluminum link (down to operating temperatures as low as 50K). Furthermore, TAI's PGL™ products are made using the industry's highest performing carbon material at cryogenic temperatures.
Because 1100 Al has roughly one third the density of copper and half the thermal conductivity, intrinsically there is a mass benefit of up to one third less for aluminum compared to copper straps. However, there are a number of other factors to consider including:
1) Aluminum straps will occupy twice the volume of copper straps for the same thermal conductance.
2) Aluminum straps are limited to stacked-foil configurations that do not provide good flexibility on each axes. This means that curvature must be included in the thermal strap design to permit directional flexibility between the strap ends. When this is done, more mass and volume are added to the strap in order to maintain a specified thermal conductance, thereby reducing any benefit over copper braided thermal straps.
3) Aluminum readily forms an oxide that can greatly degrade thermal performance at interface locations without proper surface passivation measures.
4) Aluminum foil straps are far more expensive than TAI's CuTS®, and competing AlTS are the same price as TAI's GFTS® products.
5) Aluminum straps have more handling and integration constraints than copper rope straps.
Comparison of Thermal Conductivity