The initial key of pcb design - pcb overall layout

a. Outer dimensions. When the size is too large, the printed lines are long, the impedance increases, the anti-noise ability decreases, and the cost increases. When the size is too small, the heat dissipation is not good, and the adjacent lines are susceptible to interference. Therefore, we must first give a reasonable position to the PCB size and shape.

b. Location of special components and unit circuits. According to the flow of the circuit, the entire circuit is divided into several unit circuits or modules, and the core components of each unit circuit are taken as the center, and other components are arranged on the PCB board in a certain order evenly and neatly. Can't rely too close

c. Large components, especially some relatively large and relatively high components, must have a certain distance, which is helpful for welding and repair.

d. Power integrated circuits should consider color heat sinks, leave sufficient space, and place them in a well-ventilated location. At the same time, do not be too concentrated, have a certain distance, and make them in the direction of the 45 angle.

e. Some smaller integrated circuits are arranged along the axial direction, and the capacitive elements are arranged vertically. All these directions are relative to the direction of the PCB manufacturing process. The regular arrangement of the components will reduce the defects in the welding.

f. Light-emitting diodes for display purposes are used for observation during application and may be placed at the edge of the printed board.

g. Switches, fine-tuning components, etc. should be placed in an easy-to-operate place.

h. In the same frequency circuit should consider the distribution parameters between components, general high-frequency circuits should consider the distribution parameters between components, the general circuit as much as possible parallel arrangement of components, this is not only beautiful, but also easy to install welding At the same time easy to batch production. i. Components located on the edge of the board must be 3-5 cm from the edge.

j. At the same time, consider the thermal expansion coefficient, thermal conductivity, heat resistance, and flexural strength of the PCB board so as to avoid adverse effects on the components or the PCB during production.

After the above considerations are complete, you can proceed to the next step. You can't underestimate this step. This is the beginning of a pcb board, which determines what kind of board it will be, and what kind of function it has. One step, so it is necessary to do this step.