The equipment under test must be monitored so that if the equipment fails under test, the failure is detected. Monitoring is typically performed with thermocouple sensors, vibration accelerometers, multimeters and data loggers. Common causes of failures during HALT are poor product design, workmanship, and poor manufacturing. Failures to individual components such as resistors, capacitors, diodes, printed circuit boards occur because of these issues. Failure types found during HALT testing are associated with the infant mortality region of the bathtub curve.
