Hi Amol,
Unfortunately, in most cases nobody analyzes failures. The reason is that to do a proper root cause analysis takes time, resources and expertize—and in many cases is too late for corrective action.
This is too bad, because a lot could be learned for future designs.
There are 2 important aspects to failure analysis—the physics-of-failure aspect and the statistical failure information.
Failures occur for the main part for 3 reasons: 1) inadequate design, allowing premature wear-out and/or overstress conditions, 2) insufficient quality, due to bad processing and causing latent defects, and 3) misuse.
Commercial or in-house laboratories can be utilized to establish failure modes and compliance with standards/specifications, however, the determination of the failure root cause typically requires an expert.
Werner
-----Original Message-----
From: Inge <[log in to unmask]>
To: [log in to unmask]
Sent: Sat, 7 Mar 2009 5:23 am
Subject: Re: [TN] Failure Data Analysis Techniques
We follow HDB-217 and 883 and 1553 stds in essential. One NASA example:
http://www.moasoftware.co.kr/board2/data/design/dfr07.pdf
Another typical example is this good one from EXIDA:
http://www.prelectronics.com/filer/9202_FMEDA.pdf
However, the handbook refer to one decade or more old statistics, so for
many new components derating and failure rate figures etc are not available.
You have to make your own FMEA, Arrhenius nomograms and all that stuff.
I'm not
an expert but have been involved frequently in the field. We had
several people with a PhD degree working with Failure Data Analysis, but
nowadays only one guy is left. The reason is that the reliability of many
processes has been improved a lot. One or two decades ago, we had boxes with
hundreds of components waiting for registering and analysis. Today nearly
nothing. If there are any issues, we are causing them ourselves in the
manufacturing process. And even these are few nowadays. Those of you who
have been involved, remember all the problems with tantalum caps? Or CMOS?
Or humidity in DIPs? Ahora nada de estos.
Best you can do to get answer on your questions is to call someone at NASA
(e.g. Mr Brusse, who use to read TN mails). Or ESTEC. Or Vernier Anglemajor.
Inge
----- Original Message -----
From: "Kane, Amol (349)" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, March 06, 2009 3:48 PM
Subject: [TN] Failure Data Analysis Techniques
Dear Technetters,
I am doing some research (for my PhD dissertation) on the common Failure
Data Analysis Techniques (or software) people are using in the industry to
analyze their failure data. Specifically, end of line SMT defects across all
assemblies and product lines. I realize that failure data is something that
all companies will not discuss. I am not looking for results, just methods
that you might be using to arrive at informed conclusions.
Any responses
(offline or on the forum) will be greatly appreciated
Regards,
Amol
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