Overview

Many different cases and packages have been developed to protect discrete and integrated circuit devices. The wide selection has been dictated by cost as well as the ability of the package to protect the device under the most severe environmental stresses it is likely to encounter in its intended application. The chips or dies inside must withstand shock, vibration, both operating and storage temperature excursions, chemical spills, and humidity swings. Circuit designers select package styles with one eye on cost and the other on the minimum amount of protection needed for a long useful service life.

The cases chosen for military and aerospace electronics will obviously differ from those chosen for the more tolerant industrial and automotive electronic circuits, and those, in turn, will differ from the cases typically specified for consumer products. In military, aerospace, commercial aircraft, and high-reliability applications, metal and ceramic packages are the first line of defense. Whether small-signal, IC or power devices, they are likely to be exposed to far wider temperature excursions than most industrial, commercial, or consumer-grade devices. The far higher prices charged for military-qualified devices are influenced more by the higher costs of screening, inspection, testing, and documentation mandated by military specifications than the cost of the more rugged, temperature-resistant cases.

Semiconductor devices that will be exposed to the more rigorous industrial and automotive environments are also likely to be packaged in ceramic or metal cases, but they will not undergo the same quality inspections as those conforming to MIL-S-19500, MIL-M-38510,...