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Addressing obsolescence issues in mil/aero industry

Posted: 11 Sep 2012 ?? ?Print Version ?Bookmark and Share

Keywords:Obsolescence Mitigation? OEM? COTS?

The obsolescence of all types of electronic components including integrated circuits (ICs) is a serious concern for many OEMs in the military and aerospace domain. Many of the ICs that these OEMs have designed into systems are, unfortunately, becoming obsolete for reasons beyond the control of these companies.

This article discusses some history of IC obsolescence which will help shed light on the root cause of the problem impacting Mil/Aero OEMs. The history will also describe the unintended consequences for Mil/Aero customers when they shifted from traditional high-reliability mil parts to commercial-off-the-shelf (COTS) parts.

The article also describes how the IC industry has offered several approaches to address the disruption for mil/aero OEMs. It also tackles an Obsolescence Mitigation (OM) program from Maxim, which is a collaborative effort between Maxim and an individual OEM.

Initially mil/aero customers drove the IC business
If you reflect on the military and aerospace industry and its use of ICs, you discover that the military and aerospace communities were the predominant customers for semiconductors in the 1950s and 1960s (the early years of the industry). Then, over the years, IC demand shifted from Mil/Aero applications to computer and telecommunications where usage rose during the 1970s and 1980s. Later, the computer and telecom applications were supplanted by even higher demand from consumer electronics when ICs became truly commoditized at the end of the century.

The early ICs were prone to failure from a variety of causes including wafer defects (e.g. inclusions in the crystal lattice), mask imperfections, layout errors, process variations, and similar problems. Because military and aerospace applications required high reliability, the U.S. government, through the Department of Defense among others, developed detailed methods and techniques to assure reliability from the design of the IC itself, through the wafer fabrication processes, the piece part assembly steps, and ending with the physical testing (electrical, environmental, and structural) of the device.

These manufacturing and test procedures were detailed in military standards (STDs and PRFs, pronounced "perfs"). These highly detailed and thorough specifications and procedures covered IC layout and design, even to specifications for the thickness of the metal, the coverage of the metal in the vias between layers, and the metal coverage on the contacts to the active silicon region itself. Additional specifications defined fab process quality steps and various aspects of testing for a given end environment. The end result of all these specifications was a U.S. Department of Defense series of definitions of steps for producing and testing the most reliable devices possible. This was all outlined in familiar documents like the MIL-STD-883, MIL-PRF-38535, and many more. Most IC engineers and OEMs are familiar with these testing protocols and recognize that "mil spec parts" take longer to make since the testing is very involved and time consuming.

As with all things technical, by the late 1980s and early 1990s, IC reliability had improved dramatically as manufacturing processes and quality controls evolved (Moore's Law at work). Meanwhile, as noted above, the market for ICs shifted from a focus on military to computers and telecommunications and then more recently to a focus on consumer electronics. With the IC industry emphasis now on personal communications and consumer-driven electronics, Mil/Aero OEM customers were able to obtain more complex devices. Meanwhile, the IC industry experienced far more rapid product evolution and shorter life cycles. The end result, of course, was the displacement of older ICs by newer devices. In short, while ICs were advancing, they were also being obsoleted in growing numbers and at a faster pace than perhaps anticipated by anyone.

Seeing only the rapid advancement in performance and the concomitant price decline of these new "commercial-oriented" devices, the military community longed for the improved performance (and lower cost) of these ICs. These commercial devices offered more function/performance per square micron of silicon than the traditional mil-spec parts. Moreover, the prices of the new ICs were dramatically lower. The enhanced reliability of the new generation of ICs, derived from the much improved manufacturing processes, leads many to postulate that the use of COTS devices should be seriously considered. More performance and at a lower costa true win-win!

Of course, this weighed against the staid (tried and true) view that a certified mil spec part would offer the desired long term reliability.

Into this dynamic situation stepped the famous Admiral Perry who effectively argued for, and essentially mandated, that government-funded programs use COTS parts. The government's rationale was lower cost with higher performance from the latest technologies and much improved reliability. So Program Offices began to call for COTS parts as the means to achieve Adm. Perry's call for "cost containment" for the ever more costly military applications.

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