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

摘要

A method (10) of manufacturing an environmentally robust electronic module (30) for aircraft avionics or other military or commercial electronic systems. The method (10) produces a sealed chip-on-board electronic module (30) and comprises the following steps. A printed wiring board (32) is provided having an electrical interconnection circuit printed thereon. Bare integrated circuit chips (33) are directly mounted and wirebonded to the printed wiring board (32). Solderable components are then mounted and conductively connected to the printed wiring board (32) to produce a chip-on-board electronic module (30). The chip-on-board electronic module (30) is then passivated with silicon nitride to produce a sealed chip-on-board electronic module (30). The electronic module is passivated by applying a coating (37) 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 (33) or wirebonds (36) of the electronic module (30). The silicon nitride coating (37) typically has a thickness on the order of one-half micron. After passivation, the sealed chip-on-board electronic module (30) is encapsulated (38) or a cover (38a) is disposed thereon.