AOI Optical Inspection in SMT Patch Processing: Technical Analysis and Industry Value

Abstract In SMT patch processing, AOI optical inspection (Automatic Optical Inspection) is the core link to ensure product quality. This article will deeply analyze the working principle, inspection process, core advantages and differences between AOI and SPI (solder paste inspection), and combine industry cases and data to help readers fully understand its key role in electronic manufacturing and provide feasible solution suggestions.

I. The core principle of AOI optical inspection

AOI (Automatic Optical Inspection) scans the surface of the PCB board through a high-definition CCD camera, collects images and compares them with qualified parameters in the database to identify solder joints, component mounting and process defects.

Inspection content

• Component defects: missing parts, wrong polarity, offset, reverse mounting, and tombstone effect.
• Soldering defects: short circuit, empty soldering, virtual soldering, solder balls, and solder beads.
• Process problems: uneven solder paste printing, foreign matter contamination, and abnormal component size.

II. Complete process of AOI inspection

1. Image acquisition
2. PCB board enters the equipment through the conveyor belt, and the high-definition camera scans the surface to obtain image data of components and solder joints.
3. Technical highlights: Supports 2D/3D imaging, adapting to high-density HDI boards and large-size PCBs.
4. Parameter comparison
5. Image data is compared with the preset qualified parameter library to identify abnormalities such as offset and short circuit.
6. AI algorithm: The deep learning model continuously optimizes the false alarm rate, and the accuracy rate of complex defect recognition exceeds 99%.
7. Defect marking and feedback
8. Mark the defect location through the display or automatic marking system, and feedback to the maintenance station in real time.
9. Closed-loop control: Defect data statistics generate SPC reports to help process improvement.

III. Core advantages of AOI inspection

1. High-precision replacement for manual visual inspection

• 0.01mm resolution, eliminating human errors, and improving detection consistency by more than 90%.
• Environmental adaptability: not affected by light and temperature, ensuring stable operation around the clock.

2. Real-time closed-loop control

• Millisecond response, defect interception rate up to 99.5%, avoiding defective products from being transferred to subsequent processes.
• Data-driven: Generate defect classification statistics, optimize production processes, and increase yield by 3%-8%.

3. Full-scenario adaptability

• Multi-industry coverage: Widely used in automotive electronics, new energy, and consumer electronics.
• Compatibility: Supports complex inspection requirements from 0201 micro components to BGA packaging.

Fourth, the difference between AOI and SPI: How to choose a suitable inspection solution?

Industry Recommendations: The combination of AOI + SPI can achieve full-process quality monitoring of SMT production lines, and the defect detection rate can be increased by 80%.

Five. FAQ: Answering Customers’ Frequently Asked Questions

Q1: ​​How accurate is AOI inspection?

• A: Using a 0.01mm resolution lens and combined with AI algorithms, the defect recognition accuracy rate exceeds 99%.

Q2: What types of defects can AOI detect?

• A: Including component offset, short circuit, empty solder joint, leaking solder joint, polarity error, etc.

Q3: What are the advantages of AOI compared with manual visual inspection?

• A: Eliminate human errors, increase the detection speed by 5 times, and support data analysis.

Q4: What industries is AOI suitable for?

• A: Widely used in automotive electronics, new energy, consumer electronics and other fields.

Q5: What is the cost of AOI inspection?

• A: The initial investment is high, but by reducing maintenance costs and scrap rates, the cost can be recovered within 6 months.

Q6: How to choose an AOI equipment supplier?

• A: Give priority to manufacturers that provide customized solutions, technical support and after-sales guarantees.

Summary

AOI optical inspection is an indispensable quality inspection tool in SMT patch processing. Its high precision, high efficiency and intelligent features are reshaping the electronics manufacturing industry. By combining 3D imaging, AI algorithms and data analysis, AOI not only improves product quality and yield rate, but also provides core competitiveness for enterprises to reduce costs and increase efficiency.