The Status of U.S. and International Standards Addressing the Use of Non-Hermetic Parts in Severe Operating Environments

摘要

Standard Working Groups in the U.S./Europe: The segment of the electronics industry that designs and manufactures electronic systems that operate in severely stressed environments is faced with diminishing manufacturing sources (DMS) for military grade components required in these designs. This situation is compounded further by the fact that today's microcircuits and integrated circuits, designed for the latest in surface mount technology, are available only as plastic encapsulated microcircuits (PEMs). The reluctance in the past to the use of PEMs in severely stressed environments is well founded. Failure data from the 1970s and 1980s provide proof that the porous nature of plastic encapsulated molding materials allowed the penetration of corrosive moisture, which led to premature device failures. However, as a result of semiconductor industry improvements in materials and processes in the 1990s, evidence is growing that PEMs may actually be as reliable, or even more reliable, than hermetically packaged microcircuits in specific applications, It was recognized that Industry standards were needed to control how PEMs were manufactured, packaged, and assembled on to printed circuit cards. Standards working groups were formed under the auspices of semiconductor manufacturers, the IPC [international association of printed circuit board, printed circuit board (PCB) manufacturers], and Electronics Industry Association (EIA/JEDEC). EIA is an association of original equipment manufactures (OEMs). The membership on these standards working groups includes the participation from the U.S. Department of Defense and other Government agencies, NASA, NSA, Energy, etc. These PEM working groups are developing standards and guidelines to assist the PCB designer and user in the selection of PEMs. These standards and guidelines have that been developed and published or are pending, address the design of the PCB to accommodate Plastic Encapsulated Microcircuits (PEMs), the protection of PEMs during the PCB assembly and during the soldering re-flow processes. The standards also address the qualification and characterization of PEMs by the semiconductor manufacturers prior to shipping. To be successful OEM manufacturers must applied these industry standards and guidelines for the use, characterization, and handling of PEMs to their internal processes. This paper will present the status of PEM standards.