Plastic encapsulated integrated circuits application issues for severe environments

The appropriateness of plastic encapsulated microcircuits (PEMs) in systems operating in severely stressed environments must be addressed on an application specific basis. A PEM cannot be arbitrarily substituted for a mil-spec hermetic microcircuit. Factors such as the detailed system requirements, the characteristics of the particular component, and the component's total quality management (TQM) mode of production are pertinent inputs to the design process that must be painstakingly addressed. Proponents of PEMs argue that PEMs are more available (due to high volume production), the latest in technology, light weight and smaller in size, and lower in cost. Critics are concerned that the reliability of PEMs in severe environments is uncertain, at best. The critics claim there is insufficient data on the effects of long term storage and an insufficient data on the effects of quality and reliability history to warrant their use. Standards working groups, that include semiconductor manufacturers, printed circuit board (PCB) manufacturers, and original equipment manufacturers (OEMs), with DoD participation are developing standards and guidelines to assist the designer and user in the selection of PEMs. These standards and guidelines address the design of printed circuit boards to accommodate PEMs, the protection of PEMs during the PCB assembly and soldering manufacturing processes, and the qualification and characterization of PEMs by the semiconductor manufacturer.