Introduction

AOI equipment plays an important role in many fields, and is currently mainly used in quality control, production efficiency, cost control and process improvement. In the selection of AOI equipment, we must first understand the basic structure and composition of the AOI equipment, and then combined with their actual needs, select the most suitable for their own equipment, so as to improve production efficiency and product quality.

I. The basic structure and principle of AOI machine

1. AOI inspection equipment hardware structure

• Computer mainframe: AOI equipment development place.
• Camera: AOI camera, according to the mode of image acquisition is divided into line array camera and surface array camera.
• Light source: the eyes of the AOI equipment, the light source is good or bad is to determine the strength of the AOI detection capabilities of the first step.
• Screw: The transmission device of AOI equipment, generally composed of screws and rails.
• Motor: AOI currently using the motor is divided into linear motor, servo motor and stepping motor three.
• Body: AOI equipment all parts of the carrier some suppliers called housing or rack, etc., used to fix the AOI equipment components, to achieve the AOI inspection function of the hardware structure of the carrier.

2. The principle of AOI inspection equipment

AOI technology, that is, optical automatic inspection, is an optical system imaging to realize the automatic inspection method. It uses camera technology to convert the reflected light intensity of the detected object into a quantitative gray scale value, and then compared with the gray scale value of the standard image analysis, in order to determine whether there are defects in the PCB and classified accordingly.

II. The key factors in choosing the right AOI inspection equipment

1. Performance parameters

• Resolution and accuracy: resolution is usually measured in microns (μm), determines the clarity of the inspection system. The higher the resolution, the smaller the defects that can be recognized by the equipment. Generally speaking, high resolution is required for detecting smaller components, usually at 10 μm or less. The higher the precision, the smaller the error and the more accurate the location of the detected defects.
• Detection speed: Detection speed directly affects production efficiency, high-speed image processing can significantly improve production efficiency.
• Defect coverage: The equipment should be able to detect a variety of defect types, such as wrong parts, offset, short circuit, virtual welding, standing monument, less tin, more tin, etc..
• 3D detection capability: Some high-end AOI equipment supports 3D detection, which can measure the height of solder joints and is more suitable for complex processes (such as BGA, QFN, etc.).

2. Compatibility

• PCB size range: the equipment needs to support different sizes of PCBs, from small boards (such as 50mm x 50mm) to large boards (such as 500mm x 500mm).
• Component type: the equipment needs to be able to detect a variety of package components, such as 0402, 0201, BGA, QFN, POP and so on.
• Production line integration: the equipment should support integration with MES (Manufacturing Execution System) and other systems to achieve real-time data transmission and management.

3. Hardware configuration

• Camera configuration: the resolution of the camera directly affects the quality of the image and the clarity of detection. The higher the resolution, the more the equipment can recognize small defects.
• Lens configuration: high-quality optical lens can reduce image distortion, to ensure the clarity and accuracy of the image.
• Light source configuration: common light source LED light source, white light, infrared light, etc., LED light source is the most commonly used type of light source in AOI inspection due to stable brightness and controllability.

4. Software features

• Detection algorithm: the detection algorithm is the core of the AOI equipment, used to identify and analyze defective images.
• Flexibility of the software: AOI equipment software should be adjustable in order to personalize the configuration for different products. User-friendly software interface, intelligent parameter adjustment function, automated data processing function, etc. can improve the simplicity of operation.
• Data analysis and traceability: The equipment should be able to record and store inspection data, providing trend analysis, anomaly detection and product traceability functions. These data help identify and solve potential problems and improve the controllability and efficiency of the production process.

5. After-sales service and maintenance

• Supplier reputation: choosing a reputable supplier can ensure the quality of the equipment and after-sales service.
• After-sales service: The supplier should provide perfect after-sales service.
• Training support: Suppliers should provide comprehensive training support to help operators quickly master the use of equipment and maintenance skills.

III. The characteristics of NeoDen ND800 AOI equipment

1. Inspection Items

• Stencil printing: Solder unavailability, insufficient or excessive solder, solder misalignment, bridging, stain, scratch etc.
• Component defect: missing or excessive component, misalignment, uneven, edging, opposite mounting, wrong or bad component etc.
• DIP: Missing parts, damage parts, offset, skew, inversion, etc
• Soldering defect: excessive or missing solder, empty soldering, bridging, solder ball, IC NG ,copper stain etc.

2. Calculation Method

Machine learning, color calculation, color extraction, gray scale operation, image contrast.

3. Inspection mode

PCB fully covered, with array and bad marking function.

4. SPC statistics function

Fully record the test data and make analysis, with high flexibility to check production and quality status.

5. Minimum component

0201 chip, 0.3 pitch IC.

IV. The summary

When you choose AOI equipment, you should first understand the basic knowledge of AOI equipment, and combined with their actual needs and budget, select the most suitable equipment, so as to improve the productivity of the SMT assembly line and the quality of PCB products.