Frequently Asked Questions (FAQ) - Specific Questions to FIDES Guide 2004

Q: Do the models in FIDES Guide 2004 Issue A address products that meet WEEE and RoHS requirements? If not, is a revision coming that will address WEEE and RoHS compliant material and when is the revision expected to be available?
A: 

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.

Q: Do the models in FIDES Guide 2004 Issue A address hybrids and if not how can I do?
A: 

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.

Q: Page 64 (table with packages). There is the same description for two different packages: "PBGA CSP BP 0.8 & 0.75 mm" and "PBGA flex 0.8 mm".
A: 

This two different packages are very similar and indeed have the same description.

Q: Page 64. For package type SSOP, base failure rate for SSOP with 8-10 pins are far bigger than base failure rate for SSOP with other numbers of pins. Is this correct?
A: 

No. Failure rate for SSOP with 8-10 pins (page 64) shall not be used.

Q: Page 69. Why is there a line for SOD87 package in the family "SMD, small signal, C-lead, plastic"?
A: 

This is a mistake. This part of the line shall be canceled. SOD87 are only "SMD, hermetically sealed glass".

Q: Page 69. Why are the basic failure rates of TSSOP8, TSOP6 and SO8 packages for discrete semiconductor page 69 not the same as the basic failure rates for the same packages
A: 

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.

 

CaseEquivalent Names Description?0RH(FIT)?0Tcy_Case(FIT)?0Tcy_Solder joints (FIT)

?0 Mechanical(FIT)

TSSOP 8 – Discrete Thin Shrink Small Outlines, L lead, plastic0.00745 0.000102 0.00051

0.0000051

TSOP 6 – Discrete Thin Small Outlines, leads on long edges, L lead, plastic0.0114 0.000458 0.0023

0.0000145

SO 8 - Discrete Plastic Small Outlines, L lead, plastic0.00304 0.000147 0.000734

0.0000073

 

 

 

 

 

Q: Page 72. There is some misunderstanding about λ0_Tcy_Units, λ0_Unit_mech and λ0_Tcy_casing, λ0_casing_mech?
A: 

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.

Q: Page 72. "The values of λ0_Tcy_Units, λ0_Tcy_Solder joints, λ0_Unit_mech and λ0_RH are given in the base failure rates tables associated with the packages of integrated circuits
A: 

Yes, both. In practice only some CI package are used, but they are not sorted out.

Q: Page 87. Electromechanical Relays, in the list of Application Data there is parameter Ubob, but in the formula for Electrical factor this (Ubob) parameter doesn't exists, instead we can find Uwinding. Is it the same parameter?
A: 

"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.

Q: Page 94. On the Page 94 there is formula: λ0_Connector = λ_Type * Π_report * Π_contact *Π_Cycle
A: 

This is a translation mistake. The λ0 formula shall be read with Π_mount.

Q: Page 105. For all components the acceleration factor for the mechanical stress is raised with a power of 1.5; but for wired board the stress is raised with a power of 2.8 (page 100)
A: 

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:

formule 105.gif

Q: Expression from the page 92:
A: 

formule92.gif