Method of constructing a sealed chip-on-board electronic module

A method of manufacturing an environmentally robust electronic module for aircraft avionics or other military or commercial electronic systems. The method produces a sealed chip-on-board electronic module and comprises the following steps. A printed wiring board is provided having an electrical interconnection circuit printed thereon. Bare integrated circuit chips directly mounted and wirebonded to the printed wiring board. Solderable components are then mounted and conductively connected to the printed wiring board to produce a chip-on-board electronic module. The chip-on-board electronic module is then passivated with silicon nitride to produce a sealed chip-on-board electronic module. The electronic module is passivated by applying a coating of silicon nitride using a plasma enhanced chemical vapor deposition process at a temperature near room temperature so that no stress is induced in the integrated circuit chips or wirebonds of the electronic module. The silicon nitride coating typically has a thickness on the order of one-half micron. After passivation, the sealed chip-on-board electronic module is encapsulated or a cover is disposed thereon.