SMD resistor tolerances

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  • Super_Pseudo
    New Member
    • Apr 2023
    • 3
    • None

    #1

    SMD resistor tolerances

    No tolerances are listed for SMD resistors, only the value, on pcbs.

    If I had a 1R0 Ω (i.e. 1.0 Ω), would a 1.5 Ω in-circuit reading be bad (+50%)? Or do they not go bad?

    Ty.
  • eccerr0r
    Solder Sloth
    • Nov 2012
    • 8701
    • USA

    #2
    Re: SMD resistor tolerances

    make sure you zero out your meter first.

    Comment

    • Super_Pseudo
      New Member
      • Apr 2023
      • 3
      • None

      #3
      Re: SMD resistor tolerances

      Do you have an answer on smd resistor tolerances?

      Comment

      • jiroy
        Badcaps Legend
        • Jun 2016
        • 2416
        • Lebanon

        #4
        Re: SMD resistor tolerances

        First of all , resistors and eventually most of the components should be tested outside board when dealing with resistance .
        That's said , SMD Resistors as an international standard (there will always be some exception and especially from amateur companies if I may say so) , are typically 5% tolerance when they are labeled in 3 digits , and 1% tolerance when labeled 4 digits .. Hope this help you .

        Comment

        • eccerr0r
          Solder Sloth
          • Nov 2012
          • 8701
          • USA

          #5
          Re: SMD resistor tolerances

          A resistor won't read higher than its written/banded value (within tolerance) in-circuit when the circuit is off and completely discharged. Again the most likely cause for reading low value resistors (say less than 5 ohms) higher but within about 70% of their stated resistance is due to measurement error. A Kelvin connect is much preferred to do these measurements but most DMMs do not have this functionality.

          Usually SMD resistors like any resistor will go open circuit by a lot when they fail. Having it increase a mere 50% is very uncommon.

          I haven't seen many SMD resistors that are more than 5% tolerance and quite a few of them are 1% or better, unlike typical gold-band ¼W and ⅛W through hole resistors...

          Comment

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