Electronic – Resistor failed open

resistorsvoltage divider

I am using this voltage divider circuit on a control board. Customer brought a board back stating the board wouldn't function after a few months in the field. After inspection, I found the 4.3kΩ resistor failed open. The resistor shows no signs of discoloration of any kind, but measures open. I've never seen a resistor just fail in this way. Has anyone else seen such a thing?

enter image description here

enter image description here

Best Answer

If your circuit is built with SMT resistors there is a good possibility that the failure could be due to a fracture of the resistor.

SMT fractures can be caused by:

  1. Board flexing
  2. Board vibration
  3. Improper board handling
  4. Stress in the component due to bad solder process
  5. Being hit by a tool such as a screwdriver if the resistor is located close to a board mount hole or right next to a screw terminal block where input wires are connected.

If your board is built using THMT (through hole) type resistors then a fractured component could be caused by:

  1. Board vibration
  2. Improper board handling
  3. Stress in the component due using too small of holes in board
  4. Stress in component due to holes being too close together in board or bending the leads too close to the component body.
  5. Being hit by a tool such as a screwdriver if the resistor is located close to a board mount hole or right next to a screw terminal block where input wires are connected.