Comparing Ordinary AOI and Online AOI for SMT Assembly Use

Key Takeaways

• Ordinary AOI suits low-volume production and detailed offline inspections, offering flexibility for small batches.
• Online AOI enables real-time in-line inspection, reducing rework costs by catching defects during production.
• Choose AOI based on production scale, speed requirements, budget, and quality standards.

Understanding Ordinary AOI and Online AOI in SMT Assembly Use

What Is Ordinary AOI?

Ordinary AOI (Automated Optical Inspection) performs offline PCB inspection after production. It uses cameras to detect defects like missing components or soldering issues, ideal for small batches or prototype testing.

Aspect	Description
Measurement Uncertainty	±0.4mil accuracy for defect detection
Repeatability	Consistent results under identical conditions
Design Rule Inspection	Validates PCB layouts against standards

What Is Online AOI?

Online AOI inspects PCBs in real-time during production, using image comparison to identify defects like misaligned parts or solder bridges. It integrates with production lines for high-volume manufacturing.

LTPCBA’s AOI Approach

LTPCBA combines AOI with Automated X-ray Inspection (AXI) for comprehensive checks, especially for hidden solder joints in BGAs that AOI alone can’t visualize.

Key Differences Between Ordinary AOI and Online AOI

Offline vs. Inline Inspection

• Ordinary AOI: Manual post-production inspection, prone to handling delays.
• Online AOI: Real-time in-line checking, enabling immediate defect resolution.

Production Line Integration

Online AOI boosts Overall Equipment Effectiveness (OEE) from 30% to 80% by reducing downtime, while ordinary AOI requires manual PCB handling.

Speed and Efficiency

Metric	Online AOI	Ordinary AOI
Detection Speed	Automated, high-volume	Manual, slower
Automation	Fully integrated with lines	Requires manual operation

Cost and Complexity

• Ordinary AOI: Lower upfront cost, simpler setup for small runs.
• Online AOI: Higher investment but saves costs through early defect detection.

Advantages and Disadvantages of Ordinary AOI

Benefits

• Flexibility: Adapts to diverse PCB designs.
• Short Programming Time: Quick setup for prototype testing.
• Data Collection: Tracks defect trends for process improvement.

Limitations

Challenge	Impact
Hidden Solder Joints	Misses under-BGA defects
False Defect Rates	2D systems may flag non-issues

Advantages and Disadvantages of Online AOI

Benefits

• Real-time Feedback: Cuts rework costs (e.g., defect cost from 0.40 to 45 if undetected).
• High Accuracy: Detects 95%+ surface defects, like solder bridges.
• Production Efficiency: Integrates with SMT lines for continuous flow.

Limitations

• Can’t inspect under BGAs or hidden joints.
• Time-consuming template setup for complex PCBs.
• Relies on accurate database programming.

Factors to Consider When Choosing an AOI System

Production Volume and Speed

• High-volume: Online AOI for in-line efficiency.
• Low-volume/prototyping: Ordinary AOI for flexibility.

Budget and ROI

Aspect	Online AOI	Ordinary AOI
Initial Cost	Higher	Lower
Payback Period	14–18 months for medium firms	Immediate for small runs

Quality Standards

• Class 3 (high-reliability): Online AOI for real-time compliance.
• Class 1 (consumer electronics): Ordinary AOI for cost-effective checks.

Practical Tips for SMT Assembly Use

When to Choose Ordinary AOI

• Small-batch production or custom PCB designs.
• Prototype validation and detailed offline analysis.

When to Choose Online AOI

• High-volume manufacturing with tight deadlines.
• Complex PCBs requiring immediate defect correction.

LTPCBA’s AOI Expertise

LTPCBA offers tailored AOI/AXI solutions, ensuring:

• 99.5% pass rates for delivered PCBs.
• Compliance with ISO, IATF, and UL standards.

FAQ

1. What’s AOI’s role in SMT assembly?AOI detects defects like missing components or soldering issues, improving quality and reducing rework.
2. Can ordinary and online AOI be combined?Yes—ordinary AOI for detailed offline checks and online AOI for in-line production monitoring.
3. How does LTPCBA ensure AOI compliance?LTPCBA uses advanced AOI/AXI tools that meet international quality standards, ensuring reliable results.