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  • Author Author: rscasny
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How are you be affected by the shortage of multi-layer ceramic capacitors?

The global shortage in Multi-layer Ceramic Capacitors (MLCCs) is creating a squeeze on getting them. There’s an industry-wide shortage of MLCCs, and lead times, where quoted, are up to 50 weeks on new orders. Companies are struggling to get their hands on MLCCs, which could result in production slowing down or even stopping. We’re already receiving anecdotal evidence of companies having reached line-stops because they can’t get the MLCCs to assemble their printed circuit boards.

 

So, my question is: how are you being affected by the reported shortage of MLCCs.

  • in reply to sleuz

    Hi Simon,

     

    Thanks for the link, it was very informative. I just now tried Red Expert, it is really nice to see the level of detail it provides!

  • Here's a tip for potential users of polymer aluminium caps as replacements for MLCC.

     

    The polymer parts are polarised - which most people know. What you may not know is that short exposure to small reverse voltage can damage them so that thye subsequently fail short ciruit (or very very high leakage) after the applicatrion of correct polarity bias. This can happen after anything from  a few minutes to a few hours (possibly longer - no information available).

     

    You may wonder how I know this

     

    No time for a lot of detail, but on a current project I use pos and neg 5V supplies to operate a load of op amps (about 48 of them). We have a 100uF 10V polymer aluminium cap across the negative supply to ground. If the positive supply is applied without the negative it pulls the negative rail up above ground due to the supply current of the op amps. The switching negative 5V regulator hates this because it has to start up against a 7V step rather than a 5V step so we have a diode to prevent the negative rail going more than 0.4V positive. On the latest pcb iteration we added a solderable link so that we could isolate the -5V supply for debugging. Unfortunately I put the link on the wrong side of the diode so when the link is missing the negative rail on the op amps went positive (not much, probably less than 2V). Once the link was fitted all four boards we built worked OK, two are still working but one died after about 20 minutes and the other after more than an hour (the faults being that the 100uF cap had gone short (or nearly so)).

     

    Be warned - protect your polymer electrolytics from reverse bias - and until you have more info, assume that any exposure has damaged them and replace them.

     

    If I get time I may try to characterise ths a bit better and put some more definitive numbers on it.

     

    MK

  • It's incredible how the lead times have stretched so much.. also amazing how reliant electronics is on such capacitors.

    I was just looking at the underside of a PCB, and in a space of about 2 square inches, there were easily more than a hundred of them : ) I couldn't count them, there were that many.

     

    The shortage encouraged me to do what I should have done a long time ago, purchase a LCR meter to more closely understand capacitor behavior since it doesn't match the ideal, so knowing the real-world behavior will sometimes help make choices including other capacitor technologies too.