First Article Inspection: The 48-Point Checklist Before You Approve Production

Why “I Approved the Sample” Isn’t Enough

When you approve a production sample, you’re approving one unit built with extra care by the factory’s best workers, using components selected for that specific order.

Production is different: different workers, different component batches, different production line conditions. The difference between sample quality and production quality is where most quality problems originate.

A proper FAI catches this drift before it becomes a systemic problem.

The 48-Point Inspection Protocol

Here’s the checklist we use for every new product and every new factory. It’s extensive. It’s not optional.

Visual and Physical Inspection (12 points)

Housing dimensions — Measure length, width, and thickness at three points. Compare against approved drawing. Tolerance: ±0.5mm.

Silicone color consistency — Compare to approved sample under daylight lamp. Shade variation should not be visible to the naked eye.

Surface finish — Check for flow marks, sink marks, or flash lines on the silicone housing.

LED placement accuracy — Verify LED positions against approved layout drawing. LEDs should be centered within 0.3mm of specified position.

LED alignment uniformity — All LEDs should face perpendicular to the treatment surface. Tilted LEDs create hot spots.

Switch/button tactility — Test power button and mode buttons. They should click clearly, not feel mushy.

USB/charging port fit — Insert and remove the charging cable five times. It should fit snugly without resistance.

Battery door/cover security — On battery-powered devices, verify cover clips are secure.

Label placement — Verify model number, voltage, and certification labels are in correct position.

Weight — Weigh the unit and compare to approved sample weight. Unexpected weight changes indicate component substitutions.

Packaging integrity — If packaged for shipping, verify no damage occurs during standard shipping simulation.

Wrist strap/headband security — For wearable devices, test strap attachment points for pull-out strength.

Optical Performance Testing (12 points)

Wavelength measurement — each color — Use spectrometer to measure output wavelength of red, blue, and near-infrared LEDs individually. Compare to spec. Maximum deviation: ±5nm for therapeutic wavelengths.

Power density at skin surface — Measure irradiance at 10 points across the treatment surface. Record minimum, maximum, and average. Uniformity: max deviation from average should be <20%.

Power density at operating distance — Repeat at the distance your marketing claims (typically 1-3cm for masks). This number should match your spec.

Multi-wavelength simultaneous output — When device is set to combined mode, measure each wavelength independently. Verify no single wavelength drops below 80% of single-mode output.

LED uniformity photography — Photograph the device in a dark room. Hot spots and dead zones will be immediately visible.

No flickering — Run the device under variable battery conditions. No visible flicker should occur above 70% battery.

Startup time to full output — Time from power-on to stable full output. Should be <2 seconds.

Mode switching — Verify each mode (red only, blue only, NIR only, combined) activates correctly and delivers correct wavelengths.

Timer accuracy — If the device has built-in timers (10 min, 20 min), verify accuracy against stopwatch. ±30 seconds is acceptable.

Auto shutoff functionality — Verify device automatically shuts off when timer completes.

Thermal at continuous operation — Run device at maximum output for 30 minutes. Surface temperature should not exceed 42°C.

Thermal imaging — Use thermal camera to identify hot spots. No area should exceed 45°C.

Electrical and Safety Testing (12 points)

Input voltage range — Test device across voltage range (typically 100-240V for global markets).

Charging current — Verify charging indicator shows correct status for full, charging, and empty states.

Battery capacity — Run device on full charge until auto-shutoff. Compare runtime to specification.

Leakage current — Measure chassis leakage current. Must be <0.5mA for Class II devices.

Dielectric strength — Hipot test: apply 1500V between primary and secondary circuits. No breakdown.

Grounding continuity — For metal-housed devices: ground resistance should be <0.1Ω.

USB connector polarity — Verify correct polarity on charging port.

Over-charge protection — Verify battery management system prevents overcharging.

Over-discharge protection — Verify battery management system prevents deep discharge.

Short circuit protection — Verify device survives output short circuit without damage.

Drop test — Drop from 1 meter onto concrete floor. Device should remain functional.

Flex testing on cables — For devices with wired controllers: flex cable 1000 times. No intermittent connection.

Documentation and Compliance (12 points)

User manual accuracy — Verify manual matches actual product functions, modes, and specifications.

Warranty card presence — Verify warranty terms match what was agreed in the purchase contract.

Certification labels match certificates — Confirm model numbers on device labels match the certified test reports.

RoHS compliance — Verify RoHS test report covers the specific component batch in this production run.

FCC/EMC test report — Verify the FCC ID on the device matches the test report.

Component traceability — Request bill of materials with component lot numbers. Traceable components matter for recall management.

Wavelength test report — Factory should provide spectrometer test report for this batch.

Power density test report — Factory should provide irradiance test report for this batch.

Certificate of conformance — Factory should provide a signed document stating this batch meets all agreed specifications.

Photograph comparison — Take 20 photographs of the FAI unit from standardized angles. These become your production reference.

Discrepancy log — Document every specification deviation found, no matter how small.

Sign-off documentation — FAI should be formally signed by both supplier QC manager and your company’s quality representative.

What to Do When You Find Deviations

Any deviation from spec requires a formal response from the factory:

Critical deviations (functionality, safety): Production should not start until corrected and re-inspected.

Major deviations (cosmetic, minor spec): Factory should provide corrective action plan. Production may proceed with explicit written approval and a clearly documented deviation allowance.

Minor deviations (tolerance stack-up, measurement error): Document and monitor. If the same minor deviation appears in three consecutive FAI units, escalate to major deviation status.

The FAI Report Structure

Every FAI should conclude with a formal report containing:

FAI unit identification (date, production batch, worker shift)

Photographs of every deviation found

Complete test results for all 48 points

Factory corrective action requests

Your approval or rejection decision

Conditions of approval (if any)

This report protects you. When production quality issues arise six months from now, the FAI report tells you whether this problem existed from the beginning or emerged during production.

The Most Common FAI Mistakes

Only inspecting one unit. We inspect five units minimum. If one passes and one fails, you have a problem before production even starts.

Not measuring wavelength. This is the most commonly skipped test and the one that causes the most downstream problems.

Accepting verbal explanations. If the factory tells you “that will be fixed in production,” get it in writing. And verify it on the FAI unit.

Rushing the timeline. A proper FAI takes three to five days. If the factory pressures you to approve faster, that’s a red flag about their quality priorities.

Not photographing every deviation. Disputes about whether a deviation existed at FAI stage are common. Photographs resolve them.

The first article inspection is the most important quality gate in your entire production process. Skip it to save time and you’ll spend that time many times over dealing with quality problems, customer returns, and brand damage.

Inspect it properly the first time.