Marks in PCB design are marking points typically used to promote accuracy and consistency during PCB manufacturing and assembly. These marks assist operators with automated positioning during the manufacturing process, ensuring that all components are assembled correctly and in their proper locations. This is crucial for ensuring product quality and reliability.

Below, I'll explain in detail why placing marks is necessary after PCB design is complete.

1. Improve Assembly Accuracy
Marks can improve PCB assembly accuracy. For surface mount technology (SMT), marks help assembly machines identify the position and orientation of the PCB and automatically locate components. Furthermore, marks make it easier for operators to place components in the correct locations during manual assembly.

2. Improve Manufacturing Efficiency
Marks can improve PCB manufacturing efficiency. During the initial stages of circuit board manufacturing, placing marks allows for quick PCB positioning. Compared to manually measuring PCB positions, using marks can significantly reduce manufacturing time, thereby improving efficiency and shortening manufacturing cycles.

3. Reduce Manufacturing Costs
Marks can reduce PCB manufacturing costs. By adding markings to PCBs, manufacturing plants can more easily identify and locate boards, reducing manufacturing costs. This can also reduce costs caused by manual errors, thereby improving manufacturing efficiency and lowering costs.

4. Reduce Reflow Oven Costs
Marking can reduce reflow oven costs. After components are mounted on a PCB, the reflow oven process is essential. This process requires temperature and time control to ensure soldering quality and reliability. Using markings can help the reflow oven perform automated alignment, thereby reducing defects and lowering reflow oven costs.

5. Improve PCB Stability and Reliability
Marking can improve PCB stability and reliability. These markings ensure accuracy and consistency during assembly and manufacturing, thereby improving PCB reliability and stability. This is crucial for producing high-quality, reliable products.

Overall, markings are an integral part of PCB design and are widely used in PCB manufacturing and assembly. Adding these markings to PCBs can improve assembly and manufacturing accuracy, consistency, and efficiency, thereby reducing manufacturing costs and improving PCB stability and reliability.

The above explains why we need to place a mark. Next, we'll explain its characteristics and how to create one.

The image above shows the required mark style and dimensions. The mark style consists of three elements: a 1mm diameter pad in the center, a 2mm diameter solder mask window, and a 3mm diameter conductor around the outside. The outer conductor can be polygonal or circular; there's no essential difference between the two; you can choose based on your preference.

Next, let's discuss the placement of the mark. Marks are generally placed on the side with components. If it's a single-sided layout, we only need to place one mark on the other side; we don't need to place the other. We typically place three marks on one side, near the edge of the board, usually in a corner, about 3mm from the edge.