Sheldahl can coat flexible substrates with a wide variety of coatings.  The materials listed below are the ones we most commonly coat.

Aluminum
Aluminum is the workhorse of Sheldahl's Thermal Control product line.  It can be coated on a wide range of substrates, is low in cost, has low solar absorptance, and low infrared emittance.  Multilayer insulation blankets typically include many layers of aluminized films to create very effective thermal isolation between a spacecraft and outer space.  Sheldahl uses a thicker aluminum layer than many other suppliers in order to assure excellent optical properties in a rugged coating.  When even more rugged coatings are desired, Sheldahl can protect the aluminum with an acrylic overcoat (see the adhesives based coatings page) or other specialty coating.  Sheldahl produces aluminum coatings in a high speed web processing chamber.

In addition to aluminum coatings for thermal control applications, Sheldahl has produced a number of custom films targeted to specific surface resistivity levels.  These are typically thin coatings with surface resistivity between 20 and 50 ohms per square (in contrast to Sheldahl's standard coatings with a resistivity of less than 1 ohm per square).

Silver
Silver coatings are used whenever the lowest possible absorptance levels are needed.   Silver's primary drawbacks are high cost in comparison to aluminum and its need for protection.  When used for second surface mirrors (the vast majority of applications), the silver is protected by a thin layer of inconel to prevent the silver from tarnishing.  For first surface mirrors, the silver is typically protected by a thin layer of silicon oxide.  Silver coatings are produced in batch chambers producing about 40 square feet of finished product at a time.

Gold
Gold's comparatively inert nature provides the most durable thin film coating.  Gold coated surfaces can withstand high humidity environments (as are often found around satellite launch sites) better than bare aluminum.  Gold also has the lowest infrared emittance.  Gold's biggest drawbacks are its very high price and high solar absorptance (compared to silver or aluminum).  Gold coatings can be applied on a roll to roll basis or in batch chambers producing approximately 40 square feet of finished product per run.

Indium Tin Oxide
Protection of spacecraft from electrostatic discharge build-up is becoming more important as payloads become more complex and electronics become more sophisticated.  Sheldahl has been providing moderate surface resistivity coatings (2,000 to 10,000 ohms per square) for nearly a decade.  Indium tin oxide coatings for electrostatic discharge control can be applied on a roll to roll basis or in a batch chambers producing approximately 40 square feed of finished product per run.

Sheldahl also manufactures a line of low resistivity ITO coatings in our Accentia product line.

Germanium
Germanium coatings provide an alternate approach to controlling surface electrostatic charge build-up on spacecraft.  Germanium differs from ITO in two key aspects.   First, where ITO is transparent in the visible spectrum, germanium is a moderately good reflector.  Second, germanium has extremely low insertion loss in the radio and microwave frequency ranges.

The surface resistivity of germanium coatings is much higher than ITO (in the range of 10⁷ to 10⁸ ohms per square), but is still adequate for ESD control.  Sheldahl's germanium coating has been specially developed to resist humidity problems that are often seen in these coatings.   Germanium coatings are produced in batch chambers producing about 40 square feet of finished product at a time.

Silicon Oxide (SiO₂)
Development of the International Space Station generated new categories of requirements for vacuum deposited materials on spacecraft.  Flying for many years in a low earth orbit, the ISS is the first spacecraft needing extensive protection against the reactivity of atomic oxygen.  Sheldahl's silicon oxide coatings provide the necessary protection of the films from the ravages of atomic oxygen.  Silicon oxide coatings are produced in batch chambers producing about 40 square feet of finished product at a time.

Sheldahl deposits materials on flexible substrates using thermal evaporation, electron beam evaporation, DC Magnetron sputtering, and RF sputtering.

In addition to Sheldahl's production coating chambers, we have several small bell jars for development of new coating processes.   Over the years we have developed processes for coating bismuth, chromium, copper, iron cobalt, lead, lithium, molybdenum, nickel, NiChrome, Permalloy, rhodium, tin, titanium nitride, and tungsten in addition to our more common coatings.  If you have any unique coating requirements, please contact our applications engineering group for assistance.