ceramic capacitor microscopic cracks

Discussion in 'General Electronics Chat' started by Baron, May 31, 2011.

  1. Baron

    Thread Starter Active Member

    Jun 15, 2009
    31
    0
    Is anybody here familiar with that type of problem?
    After environmental testing I observe high current leakage in several ceramic capacitors (about 4mA).
    I know these capacitors are very sensitive to mechanical and thermal stress but the first microscopic crack probably began at earlier stages (Assembly house, packaging, etc...)
    If anyone here had same experience with this problem I would glad to hear about his findings, root causes and how he solved that issue.

    Thanks

     
  2. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    Most of the ceramic capacitor problems we found were more related to bad sourcing. Our problems were cracks in large surface mount parts, 1812 and above, during environmental testing. Purchasing would use anyone and everyone to source a part at the lowest cost. We found that some companies could not track who actually made the parts that they were shipping, or were unwilling to. Once we stuck with sourcing through known manufacturers our problems were much reduced.

    Paying a little more for each part solved the difficulties that we were having...
     
  3. #12

    Expert

    Nov 30, 2010
    16,337
    6,820
    Yes. When rejects are reprocessed in third world countries and resold, you get...REJECTS!

    There might be other causes, but that is the cause I nearly assaulted my boss about.
     
  4. Baron

    Thread Starter Active Member

    Jun 15, 2009
    31
    0
    Is there any way to check or to know what the capacitor quality is?
    How can I be sure this is the main root cause without repeating enviromental testing again and again?
     
  5. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    The only way to really know the quality of the parts is to buy high quality parts. Large smt ceramic capacitors can be fragile. So, if there is still a problem then you have to look into their application and your manufacturing. We ultimately reduced our usage of the parts to a bare minimum, even paralleling smaller parts where we could.
     
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