Preserve the First Failure When a PCB Assembly Passes Retest

A PCB assembly that passes on its second attempt has two important results, not one. The first failure may indicate an intermittent product fault, a contact problem, an incomplete setup, or a test-system issue. Overwriting it with the later pass prevents the team from distinguishing those possibilities.

NI’s TestStand reporting guidance explains how result collection and report configuration determine what is retained. Review the actual logging behavior of your station. A visible result during execution is not proof that the same information survives in the saved record.

Separate unit identity from attempt identity

Use one stable identity for the physical assembly and a separate identifier for each execution. Include the station, start time, test software release, and build variant. A serial number alone cannot distinguish two attempts made on the same unit, especially when several stations may process it.

Link a retest to the earlier attempt and state why it occurred. Record whether the operator reseated the board, changed a cable, replaced a component, updated software, or made no change. Avoid the vague note “tested again,” which hides the information most useful for diagnosis.

Keep result states distinct

Do not silently convert an interrupted test into a product failure or a skipped check into a pass. The final disposition may be accepted, rejected, or held for investigation, but that decision is separate from the historical sequence of attempts.

Review the pattern across units

1. Count first-pass results separately from results after intervention.
2. Group repeated failures by step, fixture position, and station.
3. Compare intervention types with successful retests.
4. Investigate recurring patterns before changing acceptance rules.
5. Preserve the original records when a cause is confirmed.

A high eventual pass rate can hide excessive reseating or repeated retries. State whether summary metrics count physical units or executions; otherwise additional attempts can change the denominator and obscure the actual first-pass outcome. Conversely, a single retest does not prove a manufacturing defect. Use the history to decide what evidence is needed next instead of assigning the cause from the final status alone.

Close the investigation with the cause, corrective action, and affected population where known. For contact-related patterns, the fixture contact diagnosis guide explains how to separate station behavior from board defects.