What is ASTM E595?

ASTM E595 is a standard test method for total mass loss (TML) and collected volatile condensable materials (CVCM) from outgassing in a vacuum environment. Although the test itself does not specify maximum allowable limits, NASA has established requirements that are quoted and used. The most commonly quoted requirement is CVCM < 0.1% and TML < 1%. Because some water vapor (WVR) is regained after testing is complete, another (but less commonly quoted) requirement is CVCM < 0.1% and TML-WVR < 1%.

Why is Outgassing a Problem in Electronics, Optics, and Space?

When volatile compounds evaporate, they usually condense upon something else. This causes surface contamination and, depending on the contaminated material, problems such as corrosion or fogging. With microelectronics, volatiles that condense may cause devices to malfunction or fail. With optics, fogging occurs. With satellites, the vacuum pressure of outer space draws-out volatiles so that they escape more readily than at atmospheric pressure. Because it’s difficult if not impossible to repair or replace electronics and optics in outer space, it’s critical to use low-outgassing materials in applications such as satellites.

How Does SSP Make ASTM E595 EMI Silicones?

SSP has access to silicone bases and polymers from a variety of producers. This allows us to formulate specialized materials that meet customer requirements not only for physical properties, but also for outgassing – or off-gassing, as it’s sometimes called. Today, SSP is working across different silicone chemistries to combine other desirable properties such as low temperature resistance or solvent and fuel resistance with low outgassing performance.