During the PCBA manufacturing process, mark points represent a critical process step. These reference points on the PCB board serve as visual markers for automated equipment, ensuring placement machines can precisely locate and mount components. For engineers at PCBA manufacturing facilities, understanding the function and design specifications of mark points is essential for guaranteeing production quality.　　

1. Function and Importance of Mark Points　　

   1.1 What Are Mark Points?　　Mark points refer to circular or square alignment markers placed on the PCB surface, typically positioned at fixed locations on the circuit board. These markers serve no electrical function and are specifically designed to assist placement machines in achieving precise positioning during automated production. Mark points are usually located at the edges of the PCB or in blank areas between components, appearing as optically visible indicators.

   1.2 Role of Mark Points in PCBA Placement

   Precise Positioning: When handling complex circuit boards—particularly multilayer and high-density boards—placement machines use mark points to achieve accurate X, Y, and angular positioning of PCBs. This ensures components are precisely placed at designated locations.

   Enhanced Production Efficiency: By automatically recognizing Mark points, placement machines significantly reduce manual alignment and operation time, greatly improving production line automation and output efficiency.

   Error Reduction: Mark points effectively prevent component placement errors caused by minor board shifts during production. Whether due to PCB shape deviations or movement during production, Mark points enable the placement machine to calibrate through feedback, ensuring precise placement for every component. Supports Mass Production: In high-volume manufacturing, Mark points minimize human error, enhance consistency and reliability per PCB, and maintain high product yield even under complex production conditions.

   1.3 Application Scenarios for Multiple Mark Points　　

   Board Mark Points: Typically located at the edges of the PCB, board mark points serve as the most critical positioning reference throughout the entire circuit board manufacturing process. They ensure the board undergoes global calibration before entering the placement machine.　　

   Local Mark Points: Positioned around components, local mark points enable finer positioning for individual or specific areas of components. They are particularly suitable for high-precision placement of micro-sized components.　　

   Component Mark Points: Certain large or specialized components feature mark points on their surfaces. These enable machines to perform more precise operations during assembly, ensuring accurate placement.

2. Design Specifications for Mark Points

During PCB design, mark point specifications directly impact placement accuracy and efficiency. To ensure their effectiveness in production, adherence to the following design guidelines is essential.

1. 2.1 Positioning Requirements

2. Global Mark Points: Typically positioned along the diagonal edges of the PCB to ensure accurate overall board alignment. The spacing between two Mark Points should be sufficiently large to prevent alignment errors caused by minor rotation or displacement during processing.　　

3. Local Mark Points: Place local mark points in high-density areas or near components requiring exceptional precision, particularly beside components demanding high-accuracy placement like BGAs (Ball Grid Arrays).　　

4. Avoid Proximity to Via Holes, Pads, and Other Electrical Components: Mark points should be positioned away from via holes or large pads, as these structures may interfere with optical recognition accuracy.　　

5. 2.2 Shape and Dimensions　　

6. Shape: Mark points are typically designed as circles or squares, with circles being more common due to their symmetry in all directions, which aids machine recognition.

7. Size: The diameter (or side length) of a mark point is usually between 1mm and 3mm. Mark points that are too small may be difficult for machines to recognize, while those that are too large occupy excessive PCB space, affecting component layout. A diameter between 1.0mm and 1.5mm is generally recommended.　　

8. Ring-shaped Clear Zone: Sufficient solder-free space should surround the mark point, with a recommended diameter approximately twice that of the mark point itself. This prevents interference from surrounding structures during optical recognition.

9. 2.3 Surface Treatment Requirements

10. Free of Oxides and Contaminants: The mark point surface must be smooth, free of oxides and contaminants to ensure accurate optical recognition. Common surface treatments include tin plating and gold plating; materials with high reflectivity are generally recommended.

11. Contrast: The mark point should exhibit clear contrast against the PCB background color. Typically, silver or white mark points are used on dark green or black PCBs to ensure high contrast and enhance visual recognition effectiveness.