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ASIC and Component Supplier Selection for the Aerospace & Defense Markets

Fri, 07/01/2011 - 7:36am
Terry Danzer & Mike Walsh, ON Semiconductor

Mike WalshThe decision making processes that go into choosing an ASIC or component supplier can be rather complex in nature. Thorough analysis involves technical and financial criteria heavily weighing in on the selection. Obvious questions include whether or not the supplier’s product(s) can meet the technical requirements of a program, whether or not the right intellectual property to support a particular design is available, and whether they have the operational efficiencies to support competitive pricing while maintaining high quality standards.

End market dynamics may also compound the decision making process as specific requirements such as long-term product availability, quality requirements, and special processing flows can be mandatory and may trump other seemingly critical selection factors. For example, in the automotive market, suppliers are often required to support QS16949 quality standards, while the aerospace market may require support for DO-254 to provide a means of compliance for design of complex electronic hardware in airborne systems. In the aerospace and defense market, many factors may be critical for the success of the program that quite possibly might not even be considered if the product was targeting a different end application such as the consumer market.

Figure 1 - Typical Production Flow of Discrete Devices Qualified to MIL-PRF-19500 and MIL-STD-750

Unique Manufacturing, Screening, and Quality Requirements
Most end markets are satisfied with off-shore wafer fabrication and low cost plastic packaging. Contrary to the requirements of other perhaps more cost- and time-sensitive markets, high reliability applications continue to require unique and demanding manufacturing and quality flows for both ASIC and discrete products. Packaging material, for example, in most markets has evolved to require compliance with the restriction of hazardous substance directive (RoHS Compliance) and the entire elimination of lead (Pb) content. Many commercial suppliers, in turn, have eliminated any option for such an offering. Due to the reliability concern of tin whisker growth, mission-critical military and aerospace applications are temporarily exempt from this directive and still require supplier support for Sn/Pb or Ni/Pd/Au lead finish, while nearly all other volume programs have moved away from this processing. Unique requirements such as these need to be taken into consideration when evaluating sourcing.

Electronic components used in high-reliability applications are subject to rigorous manufacturing, screening and quality requirements and must demonstrate a high-reliability level to avoid in-system failure and where their failure can reasonably be expected to be extremely disruptive, if not catastrophic. For ASICs, a Qualified Manufacturers List (QML) line is set up where high-reliability screening and extended reliability testing is performed on an ongoing-basis on the manufacturing line. The Defense Logistics Agency (DLA) Land and Maritime (formerly DSCC) audits the line on a frequent basis to ensure the supplier is compliant to the military quality spec MIL-PRF-38535 (MIL-PRF-19500 for discretes). These rigorous test requirements are costly, time consuming and require a unique culture within the supplier’s organization that both understands the requirements and is willing to have a high-reliability operation to support these types of products. In addition, for ASIC products, they must be in compliance with ITAR regulations restricting the export of products and technical information.

Table 1 - DLA Land and Maritime documents  governing ICs and Discretes for QML and QPL Products used in Military and Aerospace Applications

ASIC Technology Offering - New and Legacy Required
Having a broad technology offering is a must for the aerospace and defense market. For new ASIC designs, targeting a current technology that meets performance and power requirements and also supports needed IP is the natural selection process. For military and aerospace designs where product life-cycles can be unique as compared to other end markets, careful consideration must also be given to the foundry supplier; their intent to support process longevity and availability that fits with the program requirements.

The typical product life-cycle for military and aerospace applications usually involves standard development cycle times but projects are often budgeted for a lengthy qualification cycle. Once qualified, production demand can then often run in excess of ten years. This introduces a risk down the road of the need to migrate the design to a newer, more current technology if a process discontinuance is issued by the supplier. The additional time and money required to qualify the migrated design can be costly and should be calculated into the risk factors when selecting a supplier. However, this can also be an opportunity for the design to get an overhaul to improve performance, make changes to better suit the system, or give the design the flexibility to support additional platforms that would not otherwise be considered.

Domestic Supply is a Must for certain ASIC applications
There is a sub-set of the military market that drives even more demanding services of its supplier base. There are US Government mission-critical programs that have silicon technology demand considered to be sensitive. An example application might be a military GPS positioning system. With design centers and wafer manufacturing all over the world, there is increased concern about the potential of obfuscation in the design process of a particular IC, reverse engineering the design, or tampering with the manufacturing process to create failure at the system level. The US Government is putting increased focus on ensuring mission-critical systems are being designed, manufactured, and tested in a “trusted” environment. This is achieved by only allowing silicon to be manufactured by government controlled known suppliers. Some minimum criteria for being able to offer assured access is being a US owned and US located facility, having a facility security clearance, and allowing no foreign personnel processing material in the manufacturing line.

With many of the advances in foundry offerings occurring offshore, the US Government is determined to address the offshore security concern with its assured access program. Now, many new mission-critical programs are required to be designed, wafers manufactured, and backend processed (wafer sort, assembly, and final test) all domestically with accredited suppliers. OEMs needing to deliver US Government programs and maintain compliance to this model are struggling due to a limited domestic supplier base focusing on these types of requirements.

Summary
While many end markets continue pushing ASIC and discrete suppliers towards a hyper-efficient manufacturing model with off-shore manufacturing and low cost models to achieve very aggressive cost targets, a niche market has emerged to service a the aerospace and defense electronics industry that demands mission-critical quality, ensures protection of government sensitive product, and often has requirements for decades worth of relatively small production volumes. Many suppliers have moved away from supporting such needs as it can be in conflict with objectives to serving other markets. Suppliers committed to the high-reliability market will continue to engage OEMs with these requirements, work to forge mutually beneficial and long term relationships and provide support for products requiring this type of support.

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