What is AOI (Automated Optical Inspection) in SMT equipment?

AOI (Automated Optical Inspection) equipment within SMT facilities serves as a critical tool in electronics manufacturing for assessing the quality of PCB (Printed Circuit Board) assembly. It identifies issues such as soldering defects and component misalignment through optical imaging and algorithmic analysis.

Core Functions and Principles

Inspection Scope: Primarily identifies solder joint defects (e.g., cold solder joints, bridging), missing/misplaced components, and polarity errors.

Operating Principle:

High-resolution cameras scan the PCB, capturing images;

Computers compare images against preset standards, analysing discrepancies via greyscale or 3D algorithms;

Defect locations are marked and reports generated.

Principal Types and Characteristics

In-line AOI: Integrated into production lines for real-time inspection (3-10 seconds per board), suitable for high-volume manufacturing, capable of triggering equipment to intercept defective items.

Offline AOI: Standalone sampling equipment supporting 3D solder joint analysis, suitable for small batches or multi-variety scenarios.

3D AOI: Combines X-ray technology to detect internal solder voids and complex structures (e.g., BGAs), enhancing defect coverage.

Advantages and Applications

Efficiency Enhancement: Replaces manual inspection with speeds exceeding multiple PCBs per second and low misjudgement rates.

Process Optimisation: Identifies defect root causes through SPC data analysis to adjust soldering parameters.

Industry Applications: Widely deployed in high-precision sectors like mobile phone motherboards and automotive electronics, with enterprise adoption projected to exceed 60% by 2025.