# Reliability testing: define the claim before choosing the stress. Distinguish production verification, design qualification and reliability screening, with clear test purpose, representative samples and failure analysis. Canonical: https://vieox.com/insights/electronics/electronics-reliability-testing/ Publisher: VIEOX Published: 2026-10-25 Updated: 2026-10-25 ## How should electronics manufacturers use reliability tests without overstating their meaning? Separate production acceptance from design qualification, reliability assessment and any production screening. Agree the expected use, sample configuration, failure criteria and statistical assumptions before testing. Preserve actual exposure and every failure investigation, then state what the results support. A passed stress test or a small sample with no failures does not establish unlimited life or every aspect of product safety. A product that works at the end of the line has passed a useful checkpoint. Its behaviour after transport, storage and repeated service raises different questions. Reliability testing starts by defining those questions, the product configuration they concern and the evidence needed to answer them. More severe testing is not automatically more informative. ## Name the decision the test should support A production check asks whether a manufactured unit meets the specified checks at that stage. Design qualification evaluates a defined design against agreed requirements. Reliability assessment examines performance over time under stated conditions. A production screen is intended to expose selected weaknesses in manufactured units before release. These purposes should be explicit in the plan. The same chamber or measurement equipment might support several purposes, but its presence does not make the evidence interchangeable. Record who requested the test, which configuration it covers and what decision follows. Distinguish discovering a weakness from demonstrating that a predefined requirement has been met. ## Translate the intended environment into a reviewed plan The IEC 60068-1 publisher summary describes environmental testing in relation to expected transport, storage and operational conditions, with guidance for tailoring test specifications. That framing starts with the product environment rather than a convenient chamber programme. For the actual equipment, document relevant operating modes, installation, handling, cooling and exposure assumptions. A board inside a sealed enclosure may experience different conditions from the surrounding room. Have the responsible specialists select applicable methods, severities, sequences and acceptance criteria. Keep the approved plan linked to the requirement it evaluates; a generic list of environmental tests cannot establish that coverage. Sources: [1](https://webstore.iec.ch/en/publication/501) ## Choose a sample that can answer the question NIST explains that reliability-test planning depends on the intended conclusions, assumed models and the risk of an incorrect decision. Sample size and test duration follow those choices. A number selected because it fits the available fixture may not support the desired claim. Record how specimens were selected, their material and manufacturing history, hardware revision and firmware. Note whether they represent normal production, a pilot build or a deliberate design variation. Preserve units that finish without failure as well as failed units, with their actual exposure. Explain exclusions, interruptions and replacements so the analysis does not silently become a study of only the convenient survivors. Sources: [2](https://www.itl.nist.gov/div898/handbook/apr/section3/apr31.htm) ## Keep accelerated testing and production screening distinct NIST describes accelerated life testing as using stress and failure data with models to make projections, and cautions against introducing failure mechanisms that would not occur in use. A shorter, harsher test therefore needs an engineering basis before its outcome can be translated into a service-life statement. A production screen serves a different operating purpose. Define which weaknesses it targets, how its effectiveness is evaluated and how screened units are dispositioned. Do not assume that a screen qualifies the design or that increasing severity always improves outgoing quality. Document the authorised limits and review the effects on the tested product. Sources: [3](https://itl.nist.gov/div898/handbook/apr/section3/apr314.htm) ## Treat a failure as evidence to preserve Hypothetical example: a batch of controller assemblies passes room-condition functional testing, but some units reset during an approved environmental test. The team retains the event timing, measured behaviour, specimen identities, firmware and actual chamber history. It also checks the test connections and measurement system before assigning a product cause. Keep the first observations available before repair or destructive examination changes the evidence. Link the failure-analysis plan, findings, corrective action and subsequent verification. If a modification is made, identify which specimens and configurations it affects. A successful rerun can support the next decision without erasing the original failure or automatically validating every production variant. ## Report the result with its useful limits A useful report states the tested configuration, sample selection, exposure, failure definitions, departures from the plan and conclusions supported by the analysis. Distinguish measured outcomes from extrapolated estimates. Explain whether the result supports a design decision, process investigation, supplier review or defined release action. When the design or supplier changes, ask which previous evidence remains applicable and which assumptions need review. Return relevant findings to manufacturing instructions and quality checks through the responsible owners. VIEOX welcomes a conversation about connecting test history with production context so a reliability finding can lead to a clear, accountable next step. ## Practical starting points - State whether the work is verification, qualification, assessment or screening. - Connect the plan with the intended use and environment. - Document specimen selection, configuration and actual exposure. - Keep model assumptions and unsupported extrapolations visible. - Preserve failures, interruptions and non-failed specimens. - Return findings to the design and manufacturing owners. ## Questions, answered ### Does a test with no failures prove the product cannot fail? No. It describes the observed sample during a particular exposure. The strength of a reliability conclusion depends on the plan, sample, duration and analytical assumptions, which should accompany the result. Sources: [2](https://www.itl.nist.gov/div898/handbook/apr/section3/apr31.htm) ### Can a supplier component qualification replace testing the assembled equipment? It supplies evidence about the component within its qualification scope. The assembled product adds its own configuration, connections, environment and interactions. The responsible engineering team must establish which additional validation and production checks apply. ### Should every production unit receive the design-qualification test sequence? Not automatically. Qualification and production screening have different purposes, and some evaluations consume or alter the specimens. The approved product and manufacturing plan should define the testing population and subsequent disposition. ## Sources and further reading - [IEC — IEC 60068-1:2013, Environmental testing: general and guidance, publisher summary](https://webstore.iec.ch/en/publication/501) - [NIST — How do you plan a reliability assessment test?](https://www.itl.nist.gov/div898/handbook/apr/section3/apr31.htm) - [NIST — Accelerated life tests](https://itl.nist.gov/div898/handbook/apr/section3/apr314.htm) ## Related reading - [Electronics: explore the series](https://vieox.com/insights/electronics/) - [Inspection and functional testing](https://vieox.com/insights/electronics/inspection-and-functional-test/) - [PCBA manufacturing](https://vieox.com/insights/electronics/pcba-manufacturing/) - [Automotive and power electronics](https://vieox.com/insights/electronics/automotive-and-power-electronics/) - [Component traceability and changeovers](https://vieox.com/insights/electronics/component-traceability-and-changeovers/)