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36 The PCB Magazine • September 2016 ferred to as conformal coatings within the cir- cuit board industry. The document, although officially inactive since 1998, is still widely used throughout the printed circuit board/assembly industry to this day and contains various visu- al, electrical, and environmental test methods, pertaining to the analysis of the coating mate- rial itself. MIL-PRF-31032 This military performance specification was established to test printed circuit boards and printed wiring boards in a manner that would certify they meet the necessary requirements for military use. Successful completion of the certification/qualification process results in a company being listed on the qualified manu- facturer's list (QML)—a resource that others can use for various other aspects of the marketplace. As for the document itself, requirements for ob- taining the QML listing are obviously included, along with appendices that address various re- quirements/methods grouped by technology and specific end use. MIL-PRF-50884 and MIL-PRF-55110 These military performance specifications were established to test flexible and rigid-flex printed wiring boards (MIL-PRF-50884) and rigid single-sided, double-sided, and multilay- er printed wiring boards (MIL-PRF-55110), as they pertain to military use. The main docu- ment contains general information about the qualification process, with various appendi- ces dedicated to topics such as: the qualified products list (QPL), the QML (as mentioned in the MIL-PRF-31032 section above), test- ing products to superseded design standards, as well as requirements for this qualification specifically. MIL-STD-202 This military test method standard was es- tablished for the testing of electronic and elec- trical component parts. The methods contained within the document set guidelines for envi- ronmental, physical, and electrical tests, in line with conditions expected for military operation. The test methods are grouped in the following way: environmental tests (100 class), physical characteristics tests (200 class), and electrical characteristics tests (300 class). MIL-STD-810 This military test method standard is not so much a collection of test methods, although it does have some, but more so a document to help engineers, analysts, and managers with material selection. Specifically, the direction of the document is to marry an environmental test screening process with expected design and end use environment. MIL-STD-883 This military test method standard was es- tablished for the testing of microelectronic de- vices that are destined for use within military and aerospace systems. The document as a whole is comprised of environmental, mechan- ical and electrical tests, as well as workmanship and training procedures that have been shown to ensure a specific level of quality and reliabil- ity. The test methods are grouped in the follow- ing way: environmental tests (1000 series), me- chanical tests (2000 series), electrical tests—dig- ital (3000 series), electrical tests—linear (4000 series), and test procedures (5000 series). The above descriptions are general in nature and by no means cover all of the documents that govern the military electronics world. That being said, the list is a good representation of common documents that are typically associ- ated with a PCB or a printed circuit assembly's place in the military market. At the same time, it is not uncommon for those desiring high lev- els of quality and reliability to test to these same documents even if the end use of the specific product is not military in nature. After all, the military realm is one sector of the market al- ways looking for the best products and the most dependable equipment. PCB Keith M. Sellers is operations manager with NTS in Baltimore, Maryland. DOES YOUR PRODUCT HAVE A MILITARY APPLICATION?

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