Forum: Reliability & Maintainability Questions and Answers
Posted by: Ruby
Date posted: Mon Dec 18 13:45:33 US/Eastern 2000
Subject: Component Category
I'm doing some reliability prediction of electronics equipment by using PRISM. I want to have some information about the category of the components, such as what's the differences between IC and semiconductor, what's the differences among logic IC, analog IC, and digital IC, etc.
In addition, given a part number, how could I know which category it is? For example, intel firmware hub 82802AB. Totally no idea. Any resources are very welcome. Thanks.
Posted by: FJK
Date posted: Fri Dec 15 8:32:18 US/Eastern 2000
Please let me know how the term Integrity is defined in relation to BIT and whether there is a specification reference that can be cited.
Posted by: mark schofield (email@example.com )
Date posted: Fri Dec 15 4:54:10 US/Eastern 2000
Subject: Benefits of 883 grade components
MIL-STD-883 is a parts qualification and screening program. A fundamental requirement of any screening program is that its effectiveness is measured otherwise we don't know if we are actually doing useful work or simply destroying good product. Is there any data available that substantiates the benefits of the 883 screening process or has it simply become a means to an end: "We don't know what benefits it provides but we have to do it to meet the approval". Like many of us, I am stuck in the military spec versus commercial grade component trap and need to justify decisions made as to whether or not the components we select are fit for purpose.
Posted by: Lyle Beck (firstname.lastname@example.org )
Date posted: Wed Dec 13 10:39:21 US/Eastern 2000
Subject: UA709 Op Amp instability
I am looking for some documentaion related to the USAF's listing of the UA709 Op Amp as being substantially unstable thus unuseable in avionics applications. An email regarding this would be extremely helpful in saving the taxpayers some dollars (we have to pay for this extended election somehow!)
Posted by: P Biswas (email@example.com )
Organization:Aeronautical Development Agency Bangalore
Date posted: Thu Dec 7 23:52:38 US/Eastern 2000
Subject: System MTBF predction
I am doing prediction of system MTBF that has got large number of components. The predicted value of MTBF of the system depends on (i) number of components in the system (as individual failure rate of each component is accounted in system MTBF) and (ii) their individual failure rate / MTBF value. The system MTBF has been estimated much lower than individual component MTBF since there are large number of components in the system.
[As System Failure Rate = Sum of individual Failure Rate And MTBF = 1 / (System Failure Rate) Where as the MTBF estimate based on the data from reliability tests show higher value than what we get from the prediction based on analysis. The mathematical modeling as per the RBD (complex series-parallel configuration) should approximate to the field estimate. The reason for the difference is not clear. · Whether there is some mistake in the application of this concept ? · Why the system MTBF should be less than the minimum MTBF of individual components, even after ensuring individual component MTBF ? · What alternative approach should be followed to arrive at correct prediction ? I need some expert advice who is involved in such prediction work Or can provide answer / solution.