Automated Optical Inspection

AOI Inspection for
Zero-Defect PCB Assembly

Multi-camera 3D optical scanning at every critical process stage — catching missing components, solder defects and placement errors before they ever leave the line.

3D Multi-Angle AOI Sub-20µm Resolution Inline at Every Stage Full Image Traceability
99.5%
Defect detection accuracy
15µm
Detection resolution
500+
Inspection points per board
<0.5%
False-call rate
12+
3D AOI systems in operation
100 %
Boards inspected — no sampling
3x
Inline inspection stages per board
IPC
A-610 Class 2 / 3 acceptance criteria
Defects & Issues We Catch

What our AOI systems
are trained to find

Every board is compared against a golden-board reference library. Hover to explore.

01

Missing Components

Full-board component presence check against the assembled BOM — every placement position verified against the golden reference image.

02

Tombstoning

Detects chip components lifted at one end during reflow — a common defect on small-footprint 0201/01005 passives caused by thermal imbalance.

03

Solder Bridging

Identifies unwanted solder connections between adjacent pads or leads on fine-pitch QFP, SOIC and connector packages.

04

Wrong Polarity

Verifies orientation of diodes, electrolytic capacitors and polarized ICs via marking and pin-1 recognition on every unit.

05

Insufficient Solder

Volume and profile analysis of visible solder fillets flags starved joints post-reflow before they reach electrical test.

06

Lifted Leads

Multi-angle imaging reveals leads that failed to seat flush against the pad — a leading cause of intermittent field failures.

07

Wrong Component Value

2D barcode and OCR reading cross-checks marked component values and date/lot codes against the BOM where markings are present.

08

Scratches & Etch Defects

Bare-board AOI catches copper scratches, nicks, opens/shorts in etch and solder mask defects before components are ever placed.

Our Inspection Process

How every board is
optically verified

A repeatable, programmable sequence run at multiple points in the assembly line — not a single end-of-line check.

01

Board Loading & Reference Capture

The board is indexed into the AOI station and a high-resolution reference image is captured. A first-article "golden board," verified by an engineer, anchors the inspection library for that revision.

Fixture load · golden-board reference · revision-locked library
02

Multi-Angle 3D Scan

An array of high-resolution cameras captures the board from multiple angles under structured and coaxial lighting, building a 3D surface profile that reveals lifted leads and solder volume that a single top-down image would miss.

Multi-camera array · structured light · 3D surface profiling
03

Algorithmic Defect Comparison

Captured images are compared pixel-by-pixel and feature-by-feature against the golden-board library using programmable defect algorithms tuned per component class — minimizing false calls without missing real defects.

Golden-board comparison · component-class algorithms · tuned thresholds
04

Verification, Sort & Data Logging

Flagged boards are routed to an operator review station where each suspect defect is confirmed or dismissed. Pass/reject decisions, defect images and inspection data are logged against the board's serial number for full traceability.

Operator verification · pass/reject sort · serial-level image logging
Equipment & Technology

The AOI platforms behind
every inspection

All inspection is performed in-house on production-grade equipment — nothing is outsourced.

Bare Board & Assembled PCB

3D Multi-Camera AOI Systems

High-resolution multi-angle camera arrays combined with structured-light 3D height mapping capture both the 2D footprint and the physical solder profile of every joint — detecting lifted leads and solder volume issues that flat 2D imaging cannot see.

multi-angle camera array 15µm resolution 3D height mapping
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SMT Line Integration

Inline AOI at Every Process Stage

Dedicated stations are positioned post-paste-print, post-placement and post-reflow — catching defects at the earliest possible point rather than waiting for a single end-of-line inspection, which cuts rework cost and cycle time.

post-paste-print AOI post-placement AOI post-reflow AOI
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Traceability & Reporting

Programmable Libraries & Serial-Level Logging

Each board revision has its own inspection library, built from a first-article golden board and refined over the production run. 2D barcode/OCR reading cross-checks visible component markings, and every defect image is logged against the board's unique serial number.

revision-specific libraries 2D barcode / OCR reading serial-level image archive
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Technical Specifications

AOI capability
at a glance.

Every parameter below reflects our production AOI line, verified against IPC-A-610 acceptance criteria. Inspection reports and defect images ship with every assembly order.

  • 15µm
    Detection resolution
  • 800/h
    Boards inspected per hour
  • 0.4mm
    Smallest detectable component
  • <0.5%
    False-call rate, tuned library
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ParameterAOI CapabilityStatus
Detection ResolutionDown to 15 micronsAvailable
Inspection SpeedUp to 800 boards / hourAvailable
Board Size Range50 x 50 mm – 460 x 610 mmAvailable
Camera / Angle CountMulti-camera, 6+ viewing anglesAvailable
Component Size Range01005 and largerAvailable
False-Call Rate< 0.5% on tuned libraryAvailable
Programmable LibraryPer board revision, golden-board basedAvailable
Inline StagesPost-paste, post-placement, post-reflowAvailable
Data & Image LoggingFull defect image archive per serial numberAvailable
Quality & Compliance

Certified inspection processes your quality team can audit.

AOI is one layer of a multi-stage inspection strategy. Our IPC-A-610 trained operators and documented library-tuning procedures are available for customer audit on request.

ISO 9001 : 2015
Third-party audited quality management
ISO 13485 : 2016
Medical device quality management
IATF 16949 : 2016
Automotive quality management system
IPC-A-610 Class 2 / 3
Acceptance criteria for electronic assemblies

Complementary Test & Inspection Methods

  • Solder Paste Inspection (SPI)Volume & alignment check pre-reflow, upstream of AOI
  • X-Ray Inspection — BGA & Hidden JointsCovers solder joints AOI cameras cannot see
  • In-Circuit Test (ICT)Confirms electrical integrity behind visually-passed joints
  • Flying Probe TestNet-level open/short verification, no fixture required
  • Functional TestEnd-to-end circuit performance verification
  • Final Visual InspectionManual sign-off on cosmetic and mechanical criteria
  • Microsection & Cross-section AnalysisDestructive verification on qualification samples
  • First Article Inspection (FAI) ReportsFull documentation on first production run
Case Studies

AOI inspection in practice

Real assembly challenges — and how programmable AOI caught them before shipment.

Automotive · ECU Assembly

High-Volume ECU Tombstoning Reduction

0201 passive tombstoning was slipping through end-of-line visual checks on a 20,000-unit automotive ECU run. Post-reflow inline AOI was added to catch it at source.

98%
Tombstone catch rate
20k
Units screened
0ppm
Field escapes
Outcome

Post-reflow AOI, tuned to the 0201 component library, caught every tombstoned part before functional test — eliminating rework at the customer's line.

Medical Device · Sensor Board

Polarity & Placement Verification

A Class 2 medical sensor board required 100% verification of polarized component orientation across a mixed run of diode and electrolytic packages.

100%
Boards inspected
15µm
Resolution used
0defects
Escaped to test
Outcome

Pin-1 and marking-based orientation checks flagged two mis-oriented diode lots before functional test, avoiding a costly field recall for the customer.

Telecom · High-Density Board

Fine-Pitch QFP Bridging Detection

A 0.4mm-pitch QFP network switch board showed intermittent solder bridging under standard 2D AOI. 3D multi-angle imaging was applied to resolve the issue.

0.4mm
Pin pitch
99.5%
Detection accuracy
0.3%
False-call rate
Outcome

3D height mapping isolated true bridges from shadow artifacts that were causing false calls, cutting operator review time by half while catching every real defect.

Why HanSphere

Why customers trust
our AOI process.

Optical inspection is only as good as the library behind it. Our engineers build and tune every inspection library by hand, backed by a documented, auditable process.

99.5%
Detection accuracy

High-accuracy, low-noise inspection

Our libraries are tuned per revision by trained engineers, not left on factory defaults — delivering high catch rates without burying operators in false calls.

3-stage
Inline coverage

Inspection at the point of defect creation

Post-paste, post-placement and post-reflow AOI catch issues at the earliest possible stage — reducing rework cost and preventing defects from compounding downstream.

100%
Boards imaged & logged

Full traceability, every serial number

Every board's defect images, pass/reject decision and inspection data are archived against its serial number — retrievable for any customer audit or field investigation.

<0.5%
False-call rate

Optimized libraries, not blanket rejection

We continuously refine defect algorithms per component class, cutting false-call rates that would otherwise slow down production and mask real defects in the noise.

FAQ

Frequently asked questions

Common questions about AOI inspection and how it fits into your assembly process.

Automated Optical Inspection uses high-resolution cameras to scan bare boards and assembled PCBs, comparing what the camera sees against a golden-board reference to flag defects. We run it at multiple stages: post-paste-print, post-placement and post-reflow, so issues are caught at the earliest possible point rather than at final inspection alone.

No. AOI only sees what is visible to a camera — it cannot inspect solder joints hidden underneath BGA, CSP or QFN packages. For those, we run dedicated X-ray inspection alongside AOI. The two methods are complementary, not interchangeable, and both are standard on our BGA assembly process.

AOI inspects the visible portion of a joint — fillet shape, volume and surface condition on leaded and chip components. It cannot see under a package or inside a barrel. Voiding, head-in-pillow and hidden bridging under BGA/QFN packages require X-ray inspection, which we run as a complementary step on relevant designs.

Our tuned libraries typically run below 0.5% false calls once a program is stabilized after first-article builds. We reduce false calls by building revision-specific golden-board libraries, tuning algorithm thresholds per component class, and reviewing flagged defects at an operator verification station before any board is rejected.

Yes. Every inspected board's images and pass/reject decision are archived against its serial number. On request we provide full defect image logs, inspection summary reports and traceability data for any batch, which is especially useful for root-cause investigations and customer audits.

Yes — 100% inline AOI is standard on every SMT assembly order at no extra charge. Library setup and first-article golden-board qualification is included in your first production run. Additional X-ray or ICT coverage can be added depending on your board's component mix and reliability requirements.

Get a Quote

Start your assembly
project with confidence.

Our engineering team will review your BOM and design files and return a full quote, including your inspection plan, within 8 working hours.

  • 100% inline AOI included on every assembly order
  • NDA signed on request — standard practice
  • IPC-A-610 documentation available
  • Response within 8 working hours
  • No commitment required to get a quote
Request AOI Inspection Quote All files encrypted · Max 80MB per upload · NDA available
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