Frequently Asked Questions (FAQ) - Specific Questions to FIDES Guide 2004
The RoHS requirements concern mainly (but not only) the lead-free solders. Today the substitute alloys are not stabilized. After some first investigations, the FIDES Group has concluded that it will be very hard to build realistic models in the next two years. So the answer to this question is no, this will probably not be addressed in the next issue of FIDES methodology. The WEEE requirements have for the moment, and from the FIDES Group point of view, very few or no impact on electronic design. The only possible impact identified today concern the removal of the item. In the field of aeronautic and defense were electronic board are almost ever interchangeable for easy maintenance, this is not a problem. So the answer to this question is yes, WEEE compliant product are already covered by FIDES methodology.
The FIDES Guide 2004 Issue A don't address hybrids. Hybrids family is one of the most likely expected models in the next issue of the FIDES Guide. For the moment the only solution is to break down the hybrid in component addressed by the methodology. If the right type of package can not be found, a package of the same type (hermetic/plastic, pin type and shape) may be used. Of course, this remains palliative.
This two different packages are very similar and indeed have the same description.
No. Failure rate for SSOP with 8-10 pins (page 64) shall not be used.
This is a mistake. This part of the line shall be canceled. SOD87 are only "SMD, hermetically sealed glass".
Although this data for discrete semiconductor are not a mistake, it is now recommended to use the same failure rates as for IC's packages. So the basic failure rates for this packages shall be taken in the following table.
|Case||Equivalent Names||Description||?0RH(FIT)||?0Tcy_Case(FIT)||?0Tcy_Solder joints (FIT)|
|TSSOP 8 – Discrete||Thin Shrink Small Outlines, L lead, plastic||0.00745||0.000102||0.00051|
|TSOP 6 – Discrete||Thin Small Outlines, leads on long edges, L lead, plastic||0.0114||0.000458||0.0023|
|SO 8 - Discrete||Plastic Small Outlines, L lead, plastic||0.00304||0.000147||0.000734|
This are translation mistakes. The word "case" should have been used instead of "casing" or "unit". Therefore, in this page: λ0_Tcy_case shall be read instead of λ0_Tcy_Units or λ0_Tcy_casing. λ0_mechanical_case shall be read instead of λ0_Unit_mech or λ0_casing_mech.
Yes, both. In practice only some CI package are used, but they are not sorted out.
"Bob" was an abbreviation from the French "Bobine" and should have been translated in "winding coil". Therefore U_bob is U_winding. No, the ratio U_rated / U_winding is correct. If the command voltage (U_winding) is low, the relay may have problem to operate and this accelerate failure rate.
This is a translation mistake. The λ0 formula shall be read with Π_mount.
Page 100, wired board: Because of the special construction process of this model, the
acceleration factors for wired board are specific. So this power of 2.8 is correct.
Page 105, hard disk: The acceleration factor for hard disk shall be 1.5. The right formula is: