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Subject:
From:
Gary Bremer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Gary Bremer <[log in to unmask]>
Date:
Mon, 14 Jul 2008 19:21:56 -0700
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What type of capacitors are these (polarized, non-polarized)?  I have seen polarized tantilum caps work for up to 8 hours before failure.Gary Bremer> Date: Mon, 14 Jul 2008 16:04:23 -0400> From: [log in to unmask]> Subject: Re: [TN] Ceramic caps> To: [log in to unmask]> > I don't know. They reportedly showed a short and it happened during a> test (the boards had been functional for quite a few hours and then> failed). I was assured (or should I say told) that the board temperature> should have been holding steady.> > Regards,> > Vladimir> > -----Original Message-----> From: Guy Ramsey [mailto:[log in to unmask]] > Sent: Monday, July 14, 2008 4:00 PM> To: 'TechNet E-Mail Forum'; Igoshev, Vladimir> Subject: RE: [TN] Ceramic caps> > If you energize them, do they get hot or do they then open up?> My experience with caps that fractured from end to end, the length of> the> plates, the parts opened up. It was caused by a shearing force as two> different materials expanded at different rates. I don't see how they> would> short.> > Once when I was auditing a facility I heard the sound of boards sliding> into> each other. They had built a little ramp off the reflow oven so the> parts> could slide down onto a table to cool. Things piled up at the end while> the> operator was engaged in other activities. Little SIMMs, in six up> panels, in> this case the caps were sheared off the board. > > Needless to say they had some explaining to do. > > > > -----Original Message-----> From: TechNet [mailto:[log in to unmask]] On Behalf Of Igoshev, Vladimir> Sent: Monday, July 14, 2008 3:05 PM> To: [log in to unmask]> Subject: Re: [TN] Ceramic caps> > Yes. They are all identical and they all show a short, which doesn't> make> much sense to me. That is why I keep thinking it's a manufacturing> defect.> > Regards,> > Vladimir> > -----Original Message-----> From: Stadem, Richard D. [mailto:[log in to unmask]]> Sent: Monday, July 14, 2008 3:01 PM> To: Igoshev, Vladimir; TechNet E-Mail Forum> Subject: RE: [TN] Ceramic caps> > Totally understand.> The MLCCCs are in a sort of laminated configuration, with the capacitive> plates stacked on top of dialectrics. They vary depending on the value,> ie,> the higher the capacitance, the more layers and the thinner/thicker the> dielectric in between each one. As a result, I know that higher values> of> capacitance have more of a tendency to fracture with a lateral> delamination> than smaller capacitance values do (I think I said that correctly). Are> the> caps that are fracturing all of the same value? > > -----Original Message-----> From: Igoshev, Vladimir [mailto:[log in to unmask]]> Sent: Monday, July 14, 2008 1:55 PM> To: TechNet E-Mail Forum; Stadem, Richard D.> Subject: RE: [TN] Ceramic caps> > I know Steve would do it, but I need a permission form the "local> authorities" so to say :-)> > Regards,> > Vladimir> > -----Original Message-----> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.> Sent: Monday, July 14, 2008 2:49 PM> To: [log in to unmask]> Subject: Re: [TN] Ceramic caps> > Vladimer, if you have photos you can email them to Steve Gregory. Steve> is a> gentleman and a scholar of the industry who posts photos so all of us> can> see, then it is easier to make a "root cause" analysis or just a WAG.> Steve's email address is [log in to unmask]> > -----Original Message-----> From: John Maxwell [mailto:[log in to unmask]]> Sent: Monday, July 14, 2008 1:44 PM> To: TechNet E-Mail Forum; Stadem, Richard D.> Subject: Re: [TN] Ceramic caps> > Richard & Vladimir,> It would be helpful to post the photos and then I can comment.> > John Maxwell> > Vladimir> > Here are potential causes of MLCCC cracking, and how to tell what > > caused the crack based on the crack's position, run direction, etc.> > http://www.ami.ac.uk/courses/topics/0179_fmcc/index.html#3> >> > http://www.syfer.com/category_docs/AN0005_Mechanical_Cracking.pdf> >> > And an authorative paper on the subject by John Maxwell, who I think > > knows more about root causes of cap cracking than anyone:> >> > http://www.avx.co.il/docs/techinfo/cracks.pdf> >> > And a potential solution to the problem:> >> > http://www.avx.co.il/docs/techinfo/mlccflex.pdf> >> > Qualify it first.> >> > -----Original Message-----> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Igoshev, Vladimir> > Sent: Monday, July 14, 2008 1:13 PM> > To: [log in to unmask]> > Subject: Re: [TN] Ceramic caps> >> > Well, in the case I was asking about none of the failures were in that> > > direction (across the body) but always along it splitting both ends in> > > half either vertically or horizontally. Still a puzzle to me :-)> >> > Regards,> >> > Vladimir> > > > ---------------------------------------------------> Technet Mail List provided as a service by IPC using LISTSERV 15.0 To> unsubscribe, send a message to [log in to unmask] with following text in> the> BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or> (re-start) delivery of Technet send e-mail to> [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing> per> day of all the posts: send e-mail to> [log in to unmask]: SET Technet Digest> Search the archives of previous posts at:> http://listserv.ipc.org/archives> Please visit IPC web site> http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional> information,> or contact Keach Sasamori at [log in to unmask] or 847-615-7100> ext.2815> -----------------------------------------------------> > ---------------------------------------------------> Technet Mail List provided as a service by IPC using LISTSERV 15.0 To> unsubscribe, send a message to [log in to unmask] with following text in> the> BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or> (re-start) delivery of Technet send e-mail to [log in to unmask]: SET> Technet> NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send> e-mail to [log in to unmask]: SET Technet Digest Search the archives of> previous posts at: http://listserv.ipc.org/archives Please visit IPC web> site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional> information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100> ext.2815> -----------------------------------------------------> > ---------------------------------------------------> Technet Mail List provided as a service by IPC using LISTSERV 15.0> To unsubscribe, send a message to [log in to unmask] with following text in> the BODY (NOT the subject field): SIGNOFF Technet> To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)> To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest> Search the archives of previous posts at: http://listserv.ipc.org/archives> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815> -----------------------------------------------------
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