Ten golden rules of Flex rigid PCB design：

Rule 1: Choose the right grid-set and always use the grid spacing that matches the most components. 

Although the multi-grid seems to be effective, if engineers can think more in the early stage of PCB layout design, they can avoid the problems encountered in the interval setting and maximize the application of the circuit board. Because many devices use multiple package sizes, engineers should use the product that is most conducive to their own design. In addition, polygon is very important for circuit board copper. Multi-grid circuit boards generally produce polygonal filling deviation when polygonal copper is applied. Although it is not as standard as based on a single grid, it can provide more than the required circuit board life.

Rule 2: Keep the path shortest and most direct. 

This sounds simple and common, but it should be kept in mind at every stage, even if it means to change the circuit board layout to optimize the wiring length.

Rule 3: Use the power layer as much as possible to manage the distribution of power lines and ground lines. 

The power layer copper is a faster and simpler choice for most PCB design software. By connecting a large number of wires in common, it is possible to ensure that the current with the highest efficiency and minimum impedance or voltage drop is provided, while providing sufficient ground return paths.

Rule 4: Group related components together with the required test points.

Rule 5: Copy the required circuit board on another larger circuit board multiple times for PCB imposition. 

Choosing the size that is most suitable for the equipment used by the manufacturer will help reduce the cost of prototyping and manufacturing. First carry out the circuit board layout on the panel, contact the circuit board manufacturer to obtain their preferred size specifications for each panel, then modify your design specifications, and try to repeat your design multiple times within these panel sizes.