Meaning
Maintenance procedure verifies the electrical integrity and contact resistance of probe-pin test hardware used to inspect assembled circuit boards. The ICT test fixture calibration ensures that contact resistance and signal attenuation on the spring-loaded pins fall within acceptable tolerances. This process applies to in-circuit testers on high-speed production lines and does not cover manual multi-meter probes.
Verification Procedure
Technicians perform this check by running a specialized diagnostics program that measures the contact resistance of every spring probe. The ICT test fixture calibration detects worn or contaminated pins that must be cleaned or replaced. This preventative run runs daily to ensure that the test equipment does not falsely fail good circuit boards.
Measurement Accuracy
Measurement accuracy is preserved by adjusting the software baseline to account for the resistance of the fixture wiring. This calibration step prevents the tester from registering a false open circuit when the actual board assembly has solid solder joints. Accurate calibration keeps the line running efficiently, preventing unnecessary board re-work and diagnostic labor.
Production Maintenance
Maintenance logs document these calibration events to prove that the testing process remains within the limits of the quality system. If a fixture cannot be calibrated, it is pulled from the line to prevent defective units from shipping to customers. This log serves as a record for quality audits by the product buyer.
In high-volume consumer electronics, these records must be archived for several years to track fixture wear and trace the origin of field failures back to specific production runs.
