Background
A consumer electronics EMS provider assembling smartphones and waterproof action cameras needed to move from water immersion sampling to 100% inline dry-air waterproof testing. The water immersion process tested 2% of production (AQL sampling), took 30 minutes per batch, and left devices wet — requiring a drying station before final packaging. Field return data showed IP-related failures at 0.8% — above the brand's 0.3% warranty target.
The requirement: an inline test station delivering OK/NG in under 10 seconds per unit, no water, 100% coverage, compatible with the existing conveyor loading system.
Test Requirements
| Parameter | Smartphone | Action Camera |
|---|---|---|
| IP target | IP68 (1.5 m / 30 min) | IP68 (10 m / 60 min) |
| Test method | Differential pressure | Differential pressure |
| Test pressure | 15 kPa | 25 kPa |
| Leak limit | ≤ 0.015 kPa differential over 6 s | ≤ 0.010 kPa differential over 8 s |
| Cycle time target | ≤ 8 s total | ≤ 10 s total |
| Coverage | 100% inline | 100% inline |
Solution
LD Series differential pressure instruments were installed at two dedicated inline stations — one for smartphones, one for cameras. Custom form-fitting fixture nests hold each device with a soft-seal gasket contacting the device perimeter. The LD pressurizes the enclosed air space around the device (outside-in test), comparing it against a reference cavity of identical volume.
The bridge-compensation architecture eliminates temperature and vibration noise from the production floor — critical in a factory environment where nearby pick-and-place machines and conveyor motors introduce continuous low-frequency vibration that would generate false rejects on direct pressure instruments.
Cycle timing: Seal verification (1 s) → Fill (1.5 s) → Stabilize (2 s) → Measure (3 s) → Exhaust (0.5 s) = 8 seconds total for smartphone. OK/NG signal drives a diverter gate on the conveyor — NG units are automatically rejected to a re-inspection lane without operator intervention.
Results After Deployment
- 100% coverage achieved — from 2% sampling to every unit tested
- Cycle time: 7.8 s (smartphone), 9.5 s (camera) — both within target
- Water immersion station removed — eliminated drying station and floor space
- Field IP return rate: 0.8% → 0.11% within 3 months of deployment
- False reject rate: 0.08% — below 0.1% target after fixture gasket optimization
Instruments Used
- LD Series Differential Pressure Tester — 0.01 kPa resolution, common-mode noise rejection, 8-second cycle
- Custom form-fit soft-seal fixture nests for each device model
- Conveyor diverter gate integration via digital I/O OK/NG output
- Calibrated standard leaks at 0.010 and 0.015 kPa for fixture validation
Replacing water immersion or reducing IP-related field returns? Contact us with your device type, IP target rating, and conveyor layout.
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