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A growing infrastructure of companies and organizations are available to help military system designers cope with component obsolescence, often referred to as Diminishing Manufacturing Sources and Materials Shortages (DMSMS). COTS Journal’s “Seventh Annual End-of-Life Supplier Directory,” following this article, lists over 30 of those players and what they do.
As the EOL Directory shows, there are a number of ways to deal with the problem of a chip that’s gone end-of-life. Numerous after-market chip suppliers stock inventories of obsoleted devices. Among them is a mix of small firms specializing in after-market business, as well as large distributors who include after-market products in their portfolio. In addition, some packaging firms perform custom assembly of obsolete ICs using existing wafers and die.
The Directory includes both key DoD organizations and commercial firms involved in the problems of component obsolescence, as well as the services provided by each. The three DoD organizations are the Defense Microelectronics Activity (DMEA), the Defense Supply Center Columbus (DSCC) and the Government-Industry Data Exchange Program (GIDEP).
Lead-Free: A Global Transition
However, there’s a major new wrinkle to the management of obsolete parts. An additional set of concerns has been added to complicate the issue, as the deadline looms for compliance with the European Restriction of Hazardous Substances (RoHS) directive. It restricts not only lead, but also cadmium, mercury, hexavalent chromium, polybrominated biphenyl and polybrominated diphenyl ether. Although military equipment is technically exempt from this and similar initiatives, that status could easily change. Meanwhile, related legislation is underway in Japan and China.
Even if military equipment does remain exempt programs will be affected, since commercial component manufacturers and board makers supply both the military electronics market and the much larger, worldwide commercial electronics market.
As far as the DoD is concerned, the transition to lead-free electronics is a global one, according to Kevin Rankin, chief of the DMEA’s Microelectronics Systems Branch. “Lead-free brings new and re-emerging failure modes in electronics” he says. “Lead-free exemptions will only buy us a little time. Programs are needed to develop and implement a lead-free transition strategy.”
In most cases, component manufacturers have not found it cost-effective to produce both lead-free and leaded components. “A good number are phasing out their lead-containing components, since their main market is not military/aerospace,” says Vance Anderson, a DMEA program manager focused on special projects, including RoHS.
For defense and aerospace systems, this poses special problems, since they have several unique requirements, such as high reliability, a very long service life and extended temperature ranges. The primary impacts on military/aerospace systems are performance problems with lead-free solder materials, failures caused by tin “whiskers,” the availability of leaded solder and components, and the need for new processes and configuration control to track which repairs used leaded or lead-free solder. Strategies for commercial solutions to the lead-free transition are therefore not necessarily suitable to military/aerospace applications, says Anderson.
Several different military/aerospace lead-free efforts are underway. The University of Maryland’s Computer Aided Life Cycle Engineering (CALCE) Electronic Products and Systems Center (EPSC) has produced a number of projects and tools related to lead-free issues and the tin whisker problem. It also possesses considerable research and survey data on the status of manufacturers transitioning to lead-free parts.
In other efforts, NASA’s Goddard Space Flight Center has conducted research efforts on tin whisker effects. So has the Navy’s Office of Naval Research, in conjunction with CALCE, NASA and several aircraft manufacturers and their suppliers. The Joint Council on Aging Aircraft/Joint Group on Pollution Prevention and NASA Kennedy perform lead-free solder testing for high-reliability applications.
The LEAP-WG: Best Practices, Technical Guidelines
In 2004, the Lead-Free Aerospace Electronics Working Group was formed by the Aerospace Industries Association (AIA). Now called the Lead-Free Electronics in Aerospace Project Working Group (LEAP-WG), its purpose is to develop and implement actionable deliverable items in the form of best practices and technical guidelines that enable the aerospace industry and the military to accommodate the global transition to lead-free electronics.
Under the joint aegis of the AIA, the Avionics Maintenance Conference (AMC) and the Government Electronics and Information Technology Association (GEIA), the LEAP-WG includes members from all stakeholders in different market segments, geographic regions and parts of the supply chain. “The goal was to tie in all of the parties who were forced to address the lead-free issue in the military and the aerospace/high-reliability industry,” says Anderson.
The LEAP-WG’s actionable deliverables consists of four documents. The first is GEIA-HB-0005-1, the Program Manager’s Handbook. This will be used to address all issues related to lead-free electronics, such as logistics, warranty, design, production, contracts and procurement. The second is GEIA-STD-0005-1, Performance Standard for Aerospace Electronic Systems Containing Lead-Free Solder. Aerospace electronic system customers will use this document to communicate requirements to aerospace electronic system suppliers.
The third document, GEIA-STD-0005-2, is the Technical Guidelines for Mitigating the Deleterious Effects of Pure Tin in Aerospace Electronic Systems. Finally, GEIA-HB-0005-2 is the Technical Guidelines for Using Lead-Free Solder in Aerospace Applications. Suppliers will use these guidelines to select and employ lead-free solder alloys, as well as other materials and processes.
While the LEAP-WG was formed to generate documentation, the DoD’s Executive Lead-Free Integrated Product Team (ELFIPT) looks specifically at how to deal with lead-free issues within the DoD, says Rankin. A management-level group, its DoD members include representatives from the DMEA, each military service, the Defense Logistics Agency and the Federal Aviation Administration. Other members are representatives from weapon system prime contractors. A DoD Lead-Free WG has been formed that will draw from both the LEAP-WG and the ELFIPT to recommend lead-free policy and technology investment.
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