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ceramic capacitor

Discussion in 'General Electronics Discussion' started by john_bry, Oct 31, 2011.

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  1. john_bry

    john_bry

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    Oct 31, 2011
    is it possible for a ceramic capacitor to be overheated during soldering?
    will it fail open or closed?

    will an LED fail open or closed?

    i am using a pic 12f683 to light some leds but it seems that i get a light but it is draining
    the battery within 5 seconds. its like the battery is almost shorting.
    whats wierd is the circuit works for about 5 seconds.

    thanks for your input
     
  2. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    Show us your circuit.

    Bob
     
  3. davenn

    davenn Moderator

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    Sep 5, 2009
    IC's can partly or totally fail immediately. some times it may take days or weeks to show the failure fault. Its very onpredictable cuz it depends so much on how the heat, excess voltage etc damage affected the IC.

    Ceramic caps will fail quite easily with too much heat... they can literally just fall apart

    cheers
    Dave
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,419
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    Jan 21, 2010
    OK, I see why you suspect the 1uF capacitor. It is the obvious thing across the supply rails.

    I've never failed a ceramic capacitor with too much heat and had it go short circuit. But that doesn't mean it won't, although I'd think that failing open or with a much reduced capacitance would be more likely.

    I also presume you've read the battery voltage and seen it fall to zero as soon as the power is connected, and also (probably) that the battery gets very hot. These observations would be consistent with your conclusion. To drain within a few seconds, we would also have to assume a very low battery capacity or very low internal resistance (so typically some rechargeable battery).

    I would be looking for shorts on my circuit board (I presume it's on a circuit board because you mentioned soldering this component). I'm also envisaging it as a surface mount capacitor because I've not used 1uF ceramics in a leaded form (although they may exist).

    If it is a surface mount board, it is possible that you have a misaligned component or a solder bridge causing a short. (the latter is also possible on through-hole boards too)

    I would remove the capacitor and see if the problem remains. I would also be testing the impedance across the power supply connections (without a battery) and be expecting a very low resistance if the fault remains.

    Images of your board would also probably help.
     
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