Plastic packaging is highly reliable

Plastic encapsulation is now a high reliability (HiReI) method of packaging active semiconductor devices and microelectronics in general. In this new work, tropical climates have been analyzed and shown to be appreciably more severe than those safeguarded by current hermeticity and accelerated test standards in Mil-Std-883, ''Test Methods & Procedures for Microcircuits''. Field-failure returns show that Mil-Std-883 approved hermetic CerDIP (ceramic dual-in-Line) packaged integrated circuits (IC), installed in digital switching systems, failed catastrophically with a failure rate of 1750 Fit (10(-9)/hour). The cause of failure mas severe ingress of moisture, resulting in dew-points up to 30 degrees C. Alternative indigenous developments of modular digital switches for widespread rural use in India have incorporated plastic encapsulated components selected according to the criteria developed from earlier extensive and successful reliability work by British Telecommunications (BT). Such criteria include the use of HAST (highly accelerated stress test,invented at BT Labs). The pioneering work at BT Labs demonstrated that commercial plastic packaged devices from certain sources were more reliable than their hermetic counterparts, and that both plastic & hermetic packaged devices should be subjected to similar environmental tests, including HAST, in order to separate the robust from the vulnerable packages. The invention of the non-saturating autoclave test (HAST) has proved to be an invaluable tool in the drive to develop HiReI plastic packaging. Combined with the climatic analyses. there are now clear methods for evaluating plastic packaged device reliability for various climates. Of course, tests provide only the basis for selecting the right technologies. The essence of reliability engineering is to develop the technologies and build in the reliability improvements. Other researchers have since confirmed that polymers endure as HiReI materials for packaging and interconnecting microelectronics, including pioneering work in the USA by: the IEEE Gel Task Force, AT&T, CALCE University of Maryland, as well as continuing work by BT Labs on optoelectronics, and analyses by the author of MCM technologies for satellites. The evidence is that plastic encapsulation may now be used for microelectronics & optoelectronics in telecommunications, automotive, military, and space applications as the better option in many instances. Each day's production of commercial plastic-packaged IC provides sufficient data to obtain information on parts-per-million defects, By contrast, the ponderous qualified components route for hermetic-package evaluation can take three years to obtain less than the same magnitude of data. The inexorable momentum resulting from production throughput, product quality, and good reliability for global applications will make plastic packaging the undisputed dominant encapsulation of future HiReI microelectronics.