AOI and RTG Inspection

AOI and RTG Inspection – inline AOI inspection, real‑time X‑ray inspection, quality control for smart parking

AOI and RTG Inspection is a production‑grade inspection strategy used to deliver consistent, documented quality for automotive‑grade parking sensors and mass‑market IoT parking devices. In practice, a layered inspection approach (high‑speed AOI + targeted AXI/CT) closes coverage gaps: AOI finds visible defects such as misplacement or solder bridges, while RTG (AXI/CT) finds hidden defects (BGA voids, head‑in‑pad or underside issues). Fleximodo product documentation lists electronic assembly inspection by AOI and RTG as part of its production QA for parking sensors.

Why this matters: procurement teams and municipal clients who explicitly require AOI+RTG in supplier tenders reduce escapes in the field and improve manufacturing reliability metrics.

AOI = rapid, non‑destructive visual coverage (AOI vision system).
RTG / AXI / CT = hidden defect detection where internal solder quality is critical.

Practical evidence in Fleximodo documentation: AOI and RTG inspection are listed in the device datasheet and production notes; operational lifetime and environmental qualification details are published per model.

Standards and regulatory context

Inspection strategy is shaped by three intersecting requirements: radio/EMC compliance, ingress/mechanical protection, and operator safety for RTG/X‑ray equipment. For Fleximodo sensors the EN radio tests and safety certifications were executed by accredited labs (ETSI/RED/EN 300 220 and EN 62368 series). See the test reports and datasheets for details of compliance.

Standard / Requirement	Why it matters	Typical acceptance notes	Evidence
ETSI EN 300 220‑2 (SRD / LoRa)	Required for LoRa module regulatory approval and declared band/power	Pass radio tests, declared band and power; test logs for environmental extremes are needed	Fleximodo RF test report.
IP68, IK10 (Ingress / Mechanical)	Sealing and mechanical resilience for street use	Visual AOI checks for casing integrity, torque checks for housings	Datasheets show ultrasonic welded one‑piece casing and IP68 rated enclosures.
ISO 9001 / ISO 14001	Manufacturing & environmental management	Process controls & traceability for AOI/RTG outputs	Manufacturer certification referenced in product brief.
Radiation & operator safety (local)	AXI/RTG requires shielding, training and local licensing	Shielding, interlocks, logging and local authority registration	Follow local radiological authority rules (site dependent)

Key practical note: align AOI false‑call thresholds with functional tests and life‑cycle qualification; feed AOI/RTG outputs into SPC/FMEA to close the quality loop.

Types of AOI and RTG inspection (practical view)

Common inspection elements in a sensor assembly line:

2D AOI (fast camera checks for presence/polarity/bridges) — used on SMT lines; tie to easy installation & production flows and real-time data transmission for traceability.
3D AOI / True3D — height mapping for solder fillet height and coplanarity (useful for QFN/BGA). Link to self‑calibrating sensor techniques when you need high first‑pass yield.
Inline AOI — AOI placed after reflow to get near‑real‑time feedback and to enable firmware‑over‑the‑air quality gates.
AXI / RTG / X‑ray (AXI/CT) — microfocus X‑ray and CT for internal defects; use as 100% AXI for critical boards or as sampled AXI for cost control. Map to real‑time X‑ray inspection.
Hybrid AOI→AXI — AOI first, AXI on flagged boards or statistical samples (cost‑effective balance).

References to the equipment used in those stages typically include high‑resolution cameras, 3D structured‑light heads, conveyor indexing, microfocus X‑ray hardware and AI‑assisted AOI software stacks. Tie AOI/AXI outputs to your device analytics platform (for example internal fleet monitoring such as DOTA monitoring).

System components (quick reference)

AOI vision system — cameras & programmable lighting for placement and surface defects.
3D/structured light heads for height mapping.
AXI / micro‑CT hardware for internal void/underside inspection.
AOI software + AI for faster programming and reduced false calls.
MES/SPC integration and traceability (link images to serial numbers and production lots): ensure integration with your cloud integration and secure data transmission pipelines.

How AOI and RTG Inspection is implemented — step‑by‑step

Implementation checklist (short): define targets → design AOI stations → tune AOI programs → decide AXI sampling → integrate with MES/SPC → correlate AOI/AXI/FCT → release validation.

Define acceptance targets and procurement requirements (escape rate / PPM, environmental lifetime e.g., thermal cycling -30 to +60 °C).
Map production flow and place AOI stations where feedback is fastest (after reflow is typical). Link approach with production line practices.
Program AOI (teach good/bad, fiducials, lighting) and tune for PCB finish and components.
Use 3D AOI for fillet‑height critical assemblies; calibrate height thresholds against known good boards.
Design AXI strategy (100% AXI for critical assemblies vs AOI‑flagged AXI for sampling).
Integrate AOI/AXI with MES and SPC (store images, link to serial numbers and analytics dashboards such as parking occupancy analytics).
Correlate AOI fails with AXI confirmation and FCT results to reduce false calls.
Train operators on maintenance, false‑call analysis and CAPA workflows.
Run release validation across environmental and mechanical cycles and confirm AOI/RTG flags correlate with field returns.

(Structured HowTo JSON‑LD for these steps is included in the article schema at the top.)

Maintenance & performance considerations

Daily/shift AOI camera & lighting checks — keep a reference board and image baseline.
AXI tube life and detector calibration — plan spares and log tube hours.
False‑call reduction — use AI verification engines to reduce operator review time.
Store AOI images and AXI slices for failed lots and link them to serial numbers for post‑mortem analysis.
Monitor KPIs: escape rate (PPM), false‑call rate, AOI throughput (boards/h), AXI throughput and MTBC (mean time between calibrations).

Operational note: Fleximodo datasheets and testing documents list AOI + RTG steps in the production QA stack and publish environmental qualification data per model (see datasheet references).

Call‑out — Key production tip

Align AOI false‑call thresholds with your functional test (FCT) acceptance criteria. A practical pattern: reduce AOI strictness for non‑functional cosmetic features and escalate to AXI for safety‑critical or reliability‑critical joints.

Key Takeaway — Field pilot example (benchmarked)

In short pilots and early deployments that we reviewed, sensors operated through sub‑zero cycles without premature battery failures; pilots reported no battery replacements during their test window. Use pilot telemetry and energy‑consumption logs to project lifecycle metrics conservatively (datasheet lifetime is model dependent).

Current trends and advancements

3D AOI has moved to mainstream for fillet assessment.
AI‑assisted auto‑programming reduces AOI teach time and improves first‑pass yield.
Hybrid AOI→AXI gating is the standard model to balance coverage and CAPEX.
LoRaWAN regional parameter updates and ecosystem growth make LPWAN choices even more important for large IoT rollouts; consider the LoRa Alliance RP2‑1.0.5 regional parameter update for data‑rate and airtime improvements. (lora-alliance.org)
The European Smart Cities ecosystem is actively publishing updated guidance and case studies that show the value of rigorous procurement and validation for replicable smart‑parking projects. (smart-cities-marketplace.ec.europa.eu)

Summary

AOI + RTG is the practical route to raising production yield and field reliability for parking sensors: AOI gives high‑speed surface coverage, RTG/AXI finds hidden defects. Implement correctly and integrate outputs with SPC/MES and device analytics to reduce escapes and lower TCO. Fleximodo production documentation includes AOI and RTG inspection steps and environmental qualification per sensor family.

Referencies

Below are selected Fleximodo deployments (internal project references). Each entry highlights why AOI/RTG and production QA matter in real projects and links to related glossary topics for procurement and operations.

Pardubice 2021 — 3,676 SPOTXL NBIOT sensors

Deployed: 2020‑09‑28. Large‑scale deployment (3,676 sensors) using SPOTXL NBIOT — demonstrates NB‑IoT connectivity and large‑fleet management. See NB‑IoT connectivity and sensor health monitoring.

RSM Bus Turistici — 606 SPOTXL NBIOT (Roma Capitale)

Deployed: 2021‑11‑26. Transit and bus‑parking focused install; underscores requirement for real‑time data transmission and cloud integration.

CWAY Virtual Car Park series (Portugal) — virtual car parks no. 4 & 5 (507 / 178 sensors)

Deployed 2023–2025. Virtual parking solutions that rely on accurate detection and long battery lifetime projections; map to predictive maintenance parking sensor.

Kiel Virtual Parking 1 — mixed tech (326 sensors)

Deployed: 2022‑08‑03. Mixed SPOTXL LORA and NBIOT configurations — highlights multi‑connectivity choices and the need for radio/EMC test evidence (ETSI/EN 300 220).

Chiesi HQ White & Chiesi Via Carra — indoor/outdoor SPOT MINI deployments (297 / 170 sensors)

Indoor and exterior sensor variants with ultrasonic welded casing and IP68 protection — important for underground parking sensor and ultrasonic‑welded casing.

Skypark 4 Residential Underground Parking — 221 SPOT MINI

Deployed: 2023‑10‑03. Example of underground deployment: alignment with freeze‑thaw resistance and flood‑resistant design considerations.

Henkel underground parking — 172 SPOT MINI

Deployed: 2023‑12‑18. Demonstrates the need to correlate AOI/RTG pass criteria to functional tests to avoid escapes in enclosed environments.

(Additional projects: Banská Bystrica, Wroclaw, Abu Dhabi SSMC Hospital installations, Kortrijk virtual parking — all show production scale and the diversity of site conditions that make combined AOI+RTG QA valuable.)

Internal cross‑references used above (examples): AOI vision system, IP68 ingress protection, IK10 impact resistance, LoRaWAN connectivity, NB‑IoT connectivity, Mini exterior 1.0 parking sensor, Mini interior 1.0 parking sensor, OTA firmware update, sensor health monitoring, long battery life parking sensor, maintenance-free parking sensor, self-calibrating parking sensor, parking occupancy analytics, real-time parking occupancy.

Frequently Asked Questions

What is AOI and RTG Inspection?

AOI and RTG Inspection is the combined use of automated optical inspection (AOI) and radiographic testing (RTG/AXI/X‑ray) to check PCB assemblies for visible and hidden defects during production of parking sensors.

How is AOI and RTG Inspection implemented in smart parking manufacturing?

As inline and offline inspection stations (AOI after reflow; AXI sampling rooms or inline AXI). Results feed MES/SPC and link to device serial numbers for traceability.

When should I use AXI/RTG vs 3D AOI?

Use 3D AOI for fillet height and coplanarity issues; use AXI when internal voids, underside joints or BGA reliability is a concern. Hybrid AOI→AXI gating is cost‑effective.

Can AOI achieve 100% QC by itself?

No—AOI is excellent for surface checks but cannot detect subsurface voids; RTG/AXI complements AOI to approach higher coverage for critical assemblies.

What maintenance cadence should I plan for?

AOI needs daily lighting & alignment checks; AXI needs tube/detector maintenance, logs for tube hours and regular calibration. Plan vendor contracts for critical spares.

How does AOI+RTG affect procurement for cities?

Specify AOI+RTG evidence (images, AXI slices, SPC reports) and environmental qualification runs in tenders — this reduces field returns and TCO.

Author Bio

Ing. Peter Kovács — Technical freelance writer

Ing. Peter Kovács is a senior technical writer specialising in smart‑city infrastructure. He writes for municipal parking engineers, city IoT integrators and procurement teams evaluating large tenders. Peter combines field test protocols, procurement best practices and datasheet analysis to produce practical glossary articles and vendor evaluation templates.