Outgassing materials are detrimental for critical applications that require very clean vacuum environment. Outgassing occurs when a material is placed in a vacuum environment and subjected to heat, and some of its constituents are volatilized or emitted. It is necessary to create a very clean vacuum environment for many applications, such as spacecraft equipment, sensitive analytical instruments, and lithography processing.
In order to prevent contamination in vacuum environments, the choice of materials, cleaning methods, and handling procedures must be screened by the outgassing test. The outgassing facility at ITL is capable to determine the total mass loss (TML) and collected volatile condensable material (CVCM) of materials or components when exposed to a heated vacuum environment. Mass loss may be due to outgassing of low molecular weight materials, such as trapped process solutions, uncured materials (resin, adhesive, ink, paint, coating, etc.), surface contaminants like oils and release agents used during manufacturing, and in some cases, plasticizers, flame retardants and catalysts.
The procedure in ASTM E 595 consists of heating the sample material in a vacuum chamber providing pressures of about 10-6 Torr a better. Material testing is carried out by placing known amounts of material in a 10x12x6 mm3 container boats that are placed inside a receptacle within a temperature controlling heated copper bar (see Fig. 1). The receptacle has a venting port facing a collector to measure the materials with lower volatilities. For the test, the copper bar and the materials under test are held at 125°C and the collectors at 25°C.