The military electronics industry is constantly challenged to develop products with long life cycles using COTS components.  The rapid technological advances have prompted designers to be ever vigilant about emerging technology trends and standards.  For this reason, sustainability must be a comprehensive goal when developing new products.

New technology is driven by market demand.  To accurately forecast future trends, it is  necessary to remain current with the latest industry developments.  The following list of recommendations can help manage the design process in a rapidly changing environment:

• Follow Industry Recognized Standards - A good method of collecting current information on design trends is to monitor standards that are developed by industry trade groups.  These are consensus standards developed by committees, usually consisting of a consortium of the top tier companies with representatives in their respective disciplines.  Once a standard is adopted, it definitely has a stabilizing effect on the technology.  Some common military and commercial standards include cPCI, VME, MIL-STD-1553, WCDMA, and IEEE-802.11.  
  
  
• Leveraging Supply Chain Knowledge Base – Component distributors are very connected to emerging technologies and industry trends.  The same information they use to make business decisions regarding what product lines to sell can be used to mitigate component obsolesce and improve sustainability. Recognizing the possibility of a future payoff in manufacturing, distributors are very eager to provide data on product advancements and the OEM’s technology roadmap for a particular product line.  They have access to inside information that is not readily available to the general customer base.  Obtaining knowledge of the suppliers’ future product plans is an excellent way to maximize sustainability.  

Emerging trends are not the only concern in the design for sustainability.  Conventional design techniques can be targeted as well for extending product life.

• Component Selection – The key to any successful design is component selection.  Functionality is obviously the first priority when designing new hardware. The product cost is usually second, with reliability following a close third. Future component availability usually isn’t even a consideration.  It’s very difficult to predict what parts will and will not be available in the future, but selecting the more readily available COTS components that are mass produced by multiple manufacturers can clearly reduce the risk.
  
  
• Source Selection - To maximize a product’s life cycle, it’s important to avoid sole source items that control the overall design.  Selecting multiple (two to three) vendors for critical components in advance assures that the product has flexibility in design after production.  Most supply chain management systems will drive the need for alternate sources, but the key is to have a fully qualified, drop-in replacement part.
  
  
• Designing for the Future - Designers should anticipate component advancements or the need for an alternate component by incorporating alternate locations in their circuit design to accommodate a different package design.  This method could also provide for future system expansion or additional functionality once the system is deployed.
  
  
• Package Standardization - It is recommended that the designers identify and select standard component packages and layout patterns when and wherever possible.  Using standard packages with common pin counts for typical integrated circuits (IC) makes substituting components during the design process very simple. In the future, identifying replacement components for those that have been obsoleted can be simplified.  For example, 14 or 16 pin devices are common IC packages, swapping out parts or manufacturers becomes very simple.
  
  
• Quality - Looking beyond the issues of product reliability and mean time between failure (MTBF) performance, a sustainable design needs to be sufficiently robust for a number of repair or refresh cycles. Selecting quality materials that can tolerate the environmental extremes with an adequate operational margin is one method of improving both reliability and sustainability.  A good example of this is the selection of printed circuit board (PCB) materials and PCB workmanship class.  A material such as polyimide provides greater thermal stability than FR4 and can better tolerate the localized extreme temperatures generated during the repair or upgrade process.  IPC-A-600 is a workmanship standard for PCB fabrication.  It defines the workmanship requirements for three classes of PCBs.  High reliability applications are defined as Class III products and are designed to maximize PCB reliability by requiring suppliers to have a very tightly controlled fabrication process.  Designing systems with high quality materials is an excellent foundation for product sustainability.

In conclusion, designing for sustainability is not difficult, but it can be easily over looked.  While the number one priority of a new design must be functionality, sustainability is arguably the second.  When engineers plan for the inevitability of component obsolescence, system refresh and depot repair, the overall impact on the design process can be trivial and the long term benefits significant.