Managing technical uncertainties

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MTBF calculation with FIDES 2009

MTBF-Calculation acc. to Standards

Mil-HDBK-217

Telcordia SR-332

IEC-TR-62380

Siemens SN 29500

→ FIDES 2009

217Plus

GJB/Z 299C

Like IEC-TR-63280, FIDES 2009 has been developed by the french industry. Latest issue is 2009.
Like 217Plus, FIDES uses not only technical parameters, but also "soft parameters" for assessing failure rates. This makes these two standards substantially different from all other standards.

Traditional methodology for assessing failure rates use physical and technical parameters (hard parameters).
Apart from the technical approach, FIDES (and 217Plus) uses a so called management approach, too, with a substantial amount of soft parameters derived from audit questionnaires.
Many engineers have difficulties in acknowledging that this could be a valid approach at all.

The following Ceramic Capacitor example may give some insight:

Technical parameters:

Class (-->temperature drift)
Rated voltage
termination type (polymer or other)
CV (product of current and voltage)

Soft parameters:

Maturity of the component
Maturity of the component supplier
Maturity of the production process
Maturity of the final product where the component is built in
Maturity of ..........

FIDES provides exhaustive questionnaires in order to assess all the required maturity levels. In fact these questionnaires form the major part of the more than 300 page FIDES standard.

From quality management perspective, and in contrast to the opinion of many engineers, this is definitely a valid approach, because it addresses today's main causes of unreliability better than traditional technical approaches. Reliability of today's electronic components has increased dramatically over the last decades, and therefore it is questionable to assign the root causes of component failures to weaknesses of the components themselves, while in fact today's failures are rather caused by operator misunderstanding, interface problems, misuse, noncompliance with operating procedures and specifications and the like.

FIDES methodology can be compared with ISO 9001 methodology. ISO 9001 is a management standard about process quality. Simply put: If the processes are compliant with ISO 9001 requirements, then the product quality is assumed to be good.
The FIDES methodology is similar: The better the processes, the less likely a component would fail.

Apart from the management approach, FIDES has yet another differentiator:
In addition to environment type and temperature, FIDES mission profile takes furthermore into account air pollution, air salinity and RMS vibration.

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