The probability of failure modes for different types of resistors are listed in the Article, Resistor Reliability & Failure Mode Probability Distributions. Here I will summarize the causes for failure of different types resistors.

  • A fixed composition resistors normally fail to open circuit when overheated or overly stressed due to shock or vibration.
  • A variable composition resistor may wear out after extensive use, and worn away particles may cause high resistance short circuits.
  • Wirewound resistors may experience open windings due to overheating or stress
  • Wirewound resistors may experience the windings short circuited due to accumulation of dirt, dust, breakdown of the insulation coating or high humidity.
  • Film resistors fail to open circuit when overheated or overly stressed due to shock or vibration.
  • Film resistors also fails in its stability, due to changes in resistive material characteristics resulting in increase/decrease in resistance value.
  • For all types of resistors, Excessive humidity may cause an increase in resistance.
  • Potentiometers and presets fail to open circuit due to aging and/or heavy usage of resistance tracks.
  • Potentiometers and presets gives erratic output when the wiper and/or spindle fail due to excessive usage.

To learn more about designing for high reliability, you can read my previous article, Resistor Guidelines – Design For Reliability (DFR).