The obsolescence of all types of electronic components including integrated circuits (ICs) is a serious issue for many OEMs in the military and aerospace communities. 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. Nonetheless, when all those options are assessed, there is only one mitigation solution that really works—an Obsolescence Mitigation (OM) program from Maxim. An unusual and inventive solution, OM 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.