1： The distance from the edge of the circuit board is generally not less than 2MM. The shape of the circuit board is rectangular, and the aspect ratio is 3:2 or 4:3. When the surface size of the circuit board is greater than 200MM by 150MM, the mechanical strength that the circuit board can withstand should be considered.

　　2： In general, all components should be arranged on the same side of the circuit board. Only when the top layer components are too dense can some highly limited and low heat generating devices, such as SMD resistors, capacitors, ICs, etc., be placed on the lower layer.

　　3： The minimum spacing between adjacent solder pads of different components on the PCB sample circuit board should be at least 1MM.

　　4： On the premise of ensuring electrical performance, components should be placed on a grid and arranged parallel or perpendicular to each other, in order to be neat and beautiful. In general, components are not allowed to overlap; The arrangement of components should be compact, and the components should be evenly distributed and densely distributed throughout the entire layout.