The FIDES Guide is a global methodology for reliability engineering in electronics.
The FIDES Guide contains two parts:

- A reliability prediction guide
- A reliability process control and audit guide.

The FIDES Guide aims to enable a realistic assessment of the reliability of electronic equipment, including systems operating in severe environments (aeronautics, defense systems, industrial electronics, transport, etc.). The FIDES Guide also aims to provide a concrete tool to develop and control this reliability.

The FIDES Guide key features are:
- Providing models both for electrical, electronic, and electromechanical components, and for the PWAs or some subassemblies
- Revealing and taking into consideration all technological and physical factors that play an identified role in a product's reliability
- Taking into precise consideration the mission profile
- Taking into consideration the electrical, mechanical and thermal overstresses
- Taking into consideration the failures linked to the development, production, field operation and maintenance processes
- The possibility of distinguishing several suppliers of a same component.

By identifying the factors contributing to reliability, whether technological, physical or process-based, the FIDES Guide makes it possible to revise product definition and intervene throughout the product lifecycle, to improve and control reliability.