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Diode intermittent thermal failure

Discussion in 'General Electronics Discussion' started by ddahlgren, Mar 9, 2012.

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  1. ddahlgren


    Mar 9, 2012
    I have a 1N4007 in an application that has demonstrated open circuit failure at temperatures above 100C. Circuit operates normally when temps fall below 100C. This is isolated to a few components but is relatively repeatable. No current or voltage is applied other than monitoring voltage from a meter. Is anyone familiar with this type of failure mode?
  2. shrtrnd


    Jan 15, 2010
    I don't know if we've got enough information to give you the best answer.
    The 1N4007 is a low wattage device, do you have room on the board to install a
    higher wattage diode?
    I can't remember the part number off the top of my head, but I bought some high temperature diodes at one time that helped with a similar problem I had a while back.
    (you might look into that).
    If you can't figure a way to sink the heat, and you indicated other devices are also affected,
    are you sure your circuit current isn't running too high?
    Basically, I'd consider making SURE it's the actual ambient temperature causing your
    failure, and not some circuit problem (like another device in the circuit failing at the
    high temperature, and then allowing an increase in current through your diode and other
    components that is destroying them.)
    Sometimes when I'm convinced it's a heat problem with one device, it actually turns
    out to be a problem elsewhere in the circuit, and the device I was convinced was the
    problem, was just a symptom of some other primary problem.
  3. davenn

    davenn Moderator

    Sep 5, 2009
    yes, many semiconductors will show this failure mode
    One has to ask... why the heck are you subjecting the circuitry to such abnormal temperatures. ??

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