First-pass yield is the proportion of units that meet the defined test acceptance criteria on their first completed attempt.
Why this matters in the industry
Factories use this metric to understand process stability, but station errors and retest policies can distort its meaning.
The technical reasoning
First-pass yield counts assemblies that pass their initial eligible test attempt. It reveals process and station behavior only when the attempt definition is consistent. Including retests in the numerator or silently dropping aborted attempts can make a reported improvement unrelated to actual manufacturing quality.
Using production data to separate product and station behavior
Manufacturing measurements contain variation from products and from the test process. Stable station offsets, contact wear, reference-device drift and inconsistent retest rules can alter apparent yield. A specification limit defines a product requirement; a process-control limit describes observed process behavior and serves a different purpose. Replacing one with the other can hide defects or create unnecessary rejection, so the data model must distinguish product, station and attempt identity.
How to structure the investigation
Define the denominator, excluded interruptions and treatment of incomplete tests. Separate device failures from station faults. Trend results by product, station and failure type, and retain original attempts when reporting retest outcomes.
Preserve first-attempt records and classify confirmed station interruptions separately from completed DUT failures. Trend results by station, product revision, channel and relevant operating state. Use repeated reference checks and controlled cross-station comparisons to investigate shifts. Release corrections or test-limit changes through a documented review, and evaluate whether earlier results were affected when a station fault is discovered.
Worked example or engineering scenario
If 900 of 1,000 units pass initially, first-pass yield is 90 percent. If 70 additional units later pass retest, the eventual pass rate is 97 percent; those are different metrics.
Evidence to collect
| Record | Purpose |
|---|---|
| Attempt definition | Defines the tested state and scope of the comparison. |
| Station faults | Makes the stimulus or route condition reproducible. |
| Failure classification | Supports interpretation of variation and possible confounding effects. |
| Retest treatment | Connects the observation with the stated engineering decision. |
Trade-offs and common interpretation errors
Passing a retest does not erase an intermittent failure, and improved yield does not automatically show improved radio performance. A golden device can itself change. Interpret station trends alongside reference stability and measurement uncertainty, retaining enough detail to distinguish a real process improvement from a changed test decision.
What the result can support
Report first-pass and eventual outcomes separately, with explicit handling of aborted tests and station-induced failures.
Yield improvement alone does not establish improved radio performance.
Further technical reading
Related industry knowledge
- How to Investigate RF Power Drift During a Factory Shift
- Writing Measurable RF Production Test Requirements
Numerical scenarios are illustrative assumptions, not reported measurements of a supplied product or installation.