Different point settings are required in different stages of design, and large grid points can be used for device layout in the layout stage;

For large devices such as IC and non positioning connectors, the grid precision of 50 ~ 100mil can be used for layout, while for passive small devices such as resistance, capacitance and inductance, the grid precision of 25mil can be used for layout. The accuracy of large grid points is conducive to the alignment and beautiful layout of devices.

PCB layout rules:

1. Under normal circumstances, all components shall be arranged on the same side of the circuit board. Only when the top-level components are too dense, can some devices with limited height and low calorific value, such as chip resistor, chip capacitor, chip IC, etc., be placed on the lower layer.

2. On the premise of ensuring the electrical performance, the elements shall be placed on the grid and arranged in parallel or vertical to each other in order to be neat and beautiful. Generally, the elements are not allowed to overlap; The arrangement of elements shall be compact, and the elements shall be evenly and uniformly distributed on the whole layout.

3. The minimum spacing between adjacent pad patterns of different components on the circuit board shall be more than 1mm.

4. The distance from the edge of the circuit board is generally not less than 2mm The best shape of the circuit board is rectangle, and the aspect ratio is 3:2 or 4:3 When the surface scale of the circuit board is greater than 200mm by 150mm, the mechanical strength that the circuit board can withstand shall be considered.

In the PCB layout design, the unit of the circuit board shall be analyzed, and the layout design shall be carried out according to the function. When all components of the circuit are laid out, the following principles shall be met:

1. Arrange the position of each functional circuit unit according to the circuit flow, make the layout convenient for signal flow, and keep the signal in the same direction as far as possible.

2. Take the core components of each functional unit as the center and layout around it. The components shall be evenly, integrally and compactly arranged on the PCB to minimize and shorten the lead and connection between components.