George Harman, a world authority on materials for microelectronic interconnections and packaging at the National Institute of Standards and Technology (NIST), recently made a workshop presentation for National Aeronautics and Space Administration (NASA) engineers at the Jet Propulsion Laboratory on designing semiconductor device interconnections to withstand extreme space environments.
Harman recommended that spacebound microelectronics interconnections be made with corrosion resis-tant, highly stable metals, especially gold. He also suggested the use of some newer polymers that can withstand extreme temperatures but are not yet used in the space program. "Flip chips" are another interconnection approach, that, with proper metallurgy, may make sense in high-temperature planetary environments. Instead of using wire leads around the edges of a microchip to export electrical signals, flip chips normally use a pattern of ball-shaped solder contacts that are attached directly on the chip surface. Harman suggested that NASA consider using flip chips designed with gold contacts to produce spacecraft electronics that are both space-saving and heat resistant.