Sources and control of volatile gases hazardous to hermetic electronic enclosures

Four gases that threaten operating reliability may be present in hermetic electronic enclosures. Condensates of moisture and/or ammonia can cause metallization corrosion. Hydrogen is a rapid diffuser that can degrade metal-oxide-semiconductor (MOS) device operation. Oxygen can cause oxidation and ensuing failure of solder attachment materials within the sealed package. Other gases, such as carbon dioxide, helium, argon, and organic volatiles are not threats to reliability, but do provide clues to package materials behavior. Knowing sealed package ambient gas composition helps improve materials and processes for hermetic sealing and enables process control to assure reliable products. This paper describes the analysis method for hermetic microelectronics, residual gas analysis (RGA), available at only a few laboratories worldwide. It discusses sealing processes and package piece part materials that are sources of volatiles hazardous to product reliability. It presents materials selection and improvement considerations to reduce and control dangerous volatiles in hermetic packages.