An environmental test report can say “pass” or “fail” in just one line — but for that conclusion to be valid, the pass criteria must be defined.beforewhen trying. Otherwise, the conclusion is just an opinion.
This article covers how to determine pass/fail criteria after environmental testing, how to arrange functional testing between steps, and what items are often missing from records.
1. Why pass/fail criteria must be defined before testing
Three practical reasons:
- Avoid favorable interpretations.After seeing the results, both the seller and the buyer tend to interpret it in the direction they want.
- Guaranteed reproducibility.Two different laboratories must reach the same conclusion on the same sample.
- Ensure comparability.Results between tests, suppliers, and design versions can only be compared when the criteria are the same.
2. Three points of inspection
| Time | Purpose | Notes |
|---|---|---|
| Before the test sequence | Set up comparison benchmarks: appearance, function, electrical parameters | Required. Without a baseline, deterioration cannot be concluded |
| Between steps (in a sequence) | Determine which step caused the failure | Depending on the goal: to serve design analysis, it should be done; Qualitative tests can be combined |
| While testing under extreme conditions | Detects faults that only appear at temperature/humidity extremes | Some tests require continuous monitoring or measurements under specified conditions |
| After testing and recovery | Final conclusion according to passing criteria | Must comply with specified conditions and recovery time |
3. Classifying results to write the criteria
| Type | Examples | How to treat it in the criteria |
|---|---|---|
| Serious damage | Fire, smoke, insulation breakdown, loss of safety functions, permanent deformation | Not acceptable in any case |
| Loss of function | Fails to start or to perform its function during or after the test | It is necessary to define which functions are mandatory and which are secondary |
| Parameter drift | Increased leakage current, decreased sensitivity, deviation of parameters out of tolerance | Need specific numerical thresholds and measurement conditions |
| Mechanical damage | Cracks, loose screws, plastic deformation, coating peeling | Needs a defined accept/reject boundary, with reference photographs |
| Appearance defects | Slight discolouration, minor scratches, surface marks | Usually accepted, but boundaries must be clearly stated |
| Temporary phenomenon | Error occurs at extreme temperatures but recovers automatically | Need to stipulate: accept, or must self-recover within X time |
Important point: criteria are only valid when adhered totest, conditions, timing and measurement methodsspecifically. “Not damaged” is an unverifiable statement.
4. How to write a verifiable pass criterion
A good criterion answers four questions: what to test, how to measure, what threshold, and when.
| Vague criteria | Verifiable criteria |
|---|---|
| The product still works normally | At all regulatory testing times, the product performs all 6 functions in table F; no functional errors under test conditions; The measured parameters are within the tolerances of the technical specification |
| Not damaged | After testing, there are no visible cracks on the shell surface when observed at the specified magnification; All screw joints have tightening torque within the allowable range; There are no signs of fluid leakage |
| Humidity does not affect the product | After the humidity test, the insulation resistance and leakage current measurement results are within the threshold of the technical specification sheet; There is no flashover phenomenon |
5. Handling borderline results
- Record original datawith measurement conditions, no beneficial rounding.
- Measure again when in doubt.If the result is close to the threshold, measurement uncertainty should be considered before drawing conclusions.
- Distinguish between measurement system errors and product errors.Errors in the measurement system can be mistaken for product defects.
- Clearly state the sample status when concluding.Some phenomena only appear under extreme conditions and disappear after recovery — need to be recorded separately.
- Don’t change criteria midway.If a change is required, there must be a written record and reason.
6. Records to keep when concluding pass or fail
| Section | Minimal content |
|---|---|
| Sample identification | Sample code, design version, pre-test status |
| Test | Standard number with year, test designation, severity level |
| Test conditions | Temperature, humidity, vibration data over time; how to mount; power supply status |
| Functional checks | Inspection time, method, measuring equipment, measured parameters |
| Pass criteria | The criteria document has been agreed upon, with a confirmation date |
| Evidence | Before/after photographs, recorded data, confirmation records |
7. Common mistakes
- Write the criteria after getting the results,makes the records lose objectivity.
- Only visual inspection,do not check functions and parameters.
- Measurement conditions are not recorded,making it impossible for readers to compare with the technical specifications.
- Use qualifying phraseslike “works well”, “negligible” without definition.
- Do not state the acceptance boundaryfor visual defects, leading to disputes upon delivery.
- Skip recovery before concluding,misjudging the product’s ability to recover.
8. Frequently asked questions
Who defines the pass criteria?
Usually determined by the requesting party (customer or product owner), based on technical specifications. Manufacturers should be involved to ensure verifiable criteria.
Are interim functional examinations mandatory?
Not required in all cases. If you need to know which step causes damage, you should check between steps; If only the final conclusion is needed, it can be checked later in the sequence.
How to record “pass with minor defects”?
Clearly state: meets the agreed criteria, with a description and photo of the defect, so that the recipient can self-assess the level of impact.
What if the sample fails due to a fixture error?
No conclusion means the sample fails. It is necessary to note the operation error, correct the mounting method and try again according to regulations.
May tested samples be sold?
Depends on quality policy and customer requirements. Samples that have passed environmental tests may have potential deterioration, so they are usually not used for customer deliveries.
Whose signature should the conclusion carry?
Depending on the testing room’s process and customer’s requirements. The important point is that the signer must confirm: the sample is received correctly, the test is performed correctly, and the data is truthful.
9. Conclusion
Pass/fail criteria are the part that determines the value of an environmental test report. Late definition means loss of objectivity; Vague definition means loss of reproducibility.
Three things to do: finalize criteria in writing before testing, based on measured parameters instead of feel; Full recording of measurement conditions and original data; and clearly distinguish product errors from operational errors or measurement system errors.
References
- IEC 60068-1 — Environmental testing: General provisions and guidance.
- IEC 60068-2-1, 2-2, 2-14, 2-30, 2-78 — Temperature and humidity tests.
- IEC 60068-3-7 — Measurement in loaded temperature chamber.
- IEC 60068-3-11 — Uncertainty of climatic conditions in the test chamber.
- ISO/IEC 17025 — General requirements for testing and calibration laboratory competence.
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Disclaimer
This article is an interpretive content compiled by us;not legal advice. Enterprises need to compare relevant documents/standards verbatim before applying them to specific products.
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