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Old 12-22-2011, 08:12 AM
forest gump forest gump is offline
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Smile MIL 217 Quality Factors

I need your help on MIL 217 quality factors for electronic components. How do we determine quality class for a specific type of component from the 217 table? For e.g. in ceramic capacitorís table quality factors such as S, R, P, M etc. are listed, what is the criteria to select these factors.

How does MIL quality factor co relate with the automotive grade components. Can we use our same MIL quality factor for automotive components?

Thanks...
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Old 12-22-2011, 10:45 AM
rwisniewski rwisniewski is offline
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The failure rate designation (M, P, R, S, etc.) identifies the failure rate level for which a component is qualified. The designation and quality factor varies by component type. For example, for a CDR capacitor, the failure rate levels and PI Q factors are as follows:

Failure-rate level Failure rate PI Q Factor
designation percent/1,000 hrs
____________________________________________
M........... 1.0 PI Q = 1.0
P........... 0.1 PI Q = 0.3
R........... 0.01 PI Q = 0.1
S........... 0.001 PI Q = 0.03

The appropriate failure rate designation for mil-spec qualified parts is often included in the mil-spec part number. The pertinent mil specification document would provide details for making this determination.

Parts that are not procured to military specifications, including automotive parts, are more difficult to assess. A “by the book” prediction analysis would treat these parts as having a commercial or unknown screening level with the requisite PI Q factor. However, it may possible to justify “adjustments” to this factor if you have experience data on specific components or can determine how a commercial part is manufactured and screened as compared to the military specification. Depending upon your requirements, adjustments may have to be reviewed and approved by your customer.

Additionally, 217Plus may be considered as an alternative approach to reliability predictions. Based upon more recent field data obtained on a variety of components, including those of commercial grade, it eliminates the component quality factors in favor of process grading and a reliance on actual operating and non-operating stresses.
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  #3  
Old 12-27-2011, 12:51 AM
forest gump forest gump is offline
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Quote:
Originally Posted by rwisniewski View Post
The failure rate designation (M, P, R, S, etc.) identifies the failure rate level for which a component is qualified. The designation and quality factor varies by component type. For example, for a CDR capacitor, the failure rate levels and PI Q factors are as follows:

Failure-rate level Failure rate PI Q Factor
designation percent/1,000 hrs
____________________________________________
M........... 1.0 PI Q = 1.0
P........... 0.1 PI Q = 0.3
R........... 0.01 PI Q = 0.1
S........... 0.001 PI Q = 0.03

The appropriate failure rate designation for mil-spec qualified parts is often included in the mil-spec part number. The pertinent mil specification document would provide details for making this determination.

Parts that are not procured to military specifications, including automotive parts, are more difficult to assess. A “by the book” prediction analysis would treat these parts as having a commercial or unknown screening level with the requisite PI Q factor. However, it may possible to justify “adjustments” to this factor if you have experience data on specific components or can determine how a commercial part is manufactured and screened as compared to the military specification. Depending upon your requirements, adjustments may have to be reviewed and approved by your customer.

Additionally, 217Plus may be considered as an alternative approach to reliability predictions. Based upon more recent field data obtained on a variety of components, including those of commercial grade, it eliminates the component quality factors in favor of process grading and a reliance on actual operating and non-operating stresses.
Thanks for the explanation. Can you please direct to MIL-SPEC documents for these electronic components.

Thanks...
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  #4  
Old 02-28-2012, 05:57 AM
ajaykumar ajaykumar is offline
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Join Date: Feb 2009
Posts: 37
Default Quality factor

are you using MIL-HDBK-217F or MIL-217Plus??

If you are using MIL-HDBK-217F you need not worry about quality factors. Because The MIL-217F is not updated from 1995 and it is abonded. More over for Military components the quality factor will be given in Datasheets. for other components like Commercial, automative and COTS parts i use to take MIL-SPEC Quality factor which is the value is 3. We should not take Commercial value 10 in prediction. Because there are lot of changes in capacitors models, size and other specs compare to 1995. Directly you can use MIL-SPEC for other then milatary componenets.

Coming to the 217Plus, 217plus is new standard. now a days most of the people are using 217plus for prediction. because it is depend on manufacterer specs, process grade and hope it gives acurate value.

I think its useful.
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