Presentation Title:

Speaker name:

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ESA Guidelines for using COTS Components

Ferdinando Tonicello

TEC-E, ESA-ESTEC

Abstract:                   

The presentation will address the application of COTS components and modules in modules, equipment or subsystems of different criticality categories for ESA institutional missions.

The work has been performed by a dedicated ESA working group, including a pool of experts in different technological and application domains (material and processes, components, radiation aspects, electrical applications both at subsystem and system level).

The approach intends to keep a balanced approach especially between reliability and radiation performances, according to a progressive scheme from higher to less risk taking, and allowing both an economic/experimental (but more risky) use of COTS for cost reduction reasons, and a reliable (but expensive) use of COTS for performance reasons.

Since typically not large, but small procurement lots of COTS components and modules apply to ESA missions, a special care has been given to address expected or not sure lot homogeneity (not only for reliability aspects, but also in terms of radiation tolerance).

In fact, only with guaranteed lot homogeneity one can be sure that the flight specimen has the same properties of the part that is evaluated, “qualified” and/or screened on ground.

Considering that the approach provides a set of guidelines and not requirements, the identified criticality categories at modules, equipment or subsystem level are divided in two main groups: a normative (“green”) area and an informative (“yellow”) one.

See Figure 1.

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COTS, overall approach

Figure 1, COTS, overall approach

The normative (“green”) area addresses COTS components and modules for which homogeneity of procurement lot is expected, and therefore for which evaluation, “qualification” and/or screening activities make sense.

In this case, the proposed approach is the one given in the ECSS-Q-ST-60-13 standard and in all ECSS applicable standards. The relevant criticality category is then Q0, and it is subdivided in three components classes as shown in Figure 2.

The informative (“yellow”) area addresses COTS components and modules for which homogeneity of procurement lot is aimed at but not fully sure, and therefore for which evaluation, “qualification” and/or screening activities are not fully effective.
In this case, the proposed approach identifies two criticality categories:

  • Q2, the most risky and economic;
  • Q1, less risky and more expensive than Q2.

The presentation will provide the application perimeters of the criticality categories, identifying the reliance on design mitigation techniques and reference designs to minimise the risk especially related to radiation tolerance and random quality issues at EEE component level.

 

ECSS-Q-ST-60-13C, summary (annex G)

Figure 2, ECSS-Q-ST-60-13C, summary (annex G)

For each criticality category, the following aspects are addressed:

  • Perimeter of application
  • Methods to resolve the critical points relevant to
    • RAMS
    • Material and processes
    • EEE components general issues
    • Radiation
    • Economy of scale
    • Application, including
      • approaches for data sheets review
      • electrical analyses needs
      • mitigation techniques
      • reference application circuits
      • modules

Finally, a set of recommended activities are identified to finalise the proposed COTS components and modules approach:

  1. Update of ECSS-Q-ST-60-13C
  2. Identification of safe operation factors for criticality categories Q2 and Q1
  3. COTS components and modules information gathering
  4. Reference application circuits
  5. New test methods for modules and boards
  6. Lead free recommendations
  7. Good practices for Radiation
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