System effectiveness activities in support of long life communications satellites

Action taken to overcome problems with latching relays, RF transistors, Schottky diodes, traveling wave tubes, hybrid circuits, and printed wire boards is described. The roles of product design control, quality assurance, parts, materials and processes control, reliability, safety and acceptance tests are highlighted. The current flow in relays which is blocked by a microscopic carbonaceous film is discussed. The transistors fail because of a parasitic oscillation within the transmitter and the repeated pulse degradation mechanism of the diodes is incorrect. Toluene cleaning causes conformal coatings to swell by up to 70%, breaking wire bonds in hybrid circuits, while a short between a diode and a hole on the circuit board causes printed wire boards to fail. Contact between a transformer winding and around potential wire which leads to short circuits in traveling wave tubes is discussed.