PCB Technical - Common layout principles of PCB boards

Common layout principles of PCB boards
1. Component arrangement rules
1). Under normal conditions, all PCB components should be arranged on the same surface of the PCB boards. Only when the top components are too dense, can some devices with limited height and low heat generation, such as chip resistors and chip Capacitors, paste ICs, etc. are placed on the bottom layer.
2). Under the premise of ensuring electrical performance, the components should be placed on the grid and arranged parallel or perpendicular to each other in order to be neat and beautiful. Under normal circumstances, components are not allowed to overlap; the arrangement of components should be compact, and the input and output components should be as far away as possible .
3). There may be a relatively high potential difference between certain components or wires, and their distance should be increased to avoid accidental short circuits due to discharge and breakdown.
4). Components with high voltage should be arranged as far as possible in places that are not easily reachable by hands during debugging.
5). Components located at the edge of the board should be at least 2 board thickness away from the edge of the board
6). Components should be evenly distributed and densely distributed on the entire PCB boards,.
2. Follow the principle of signal layout

1). The position of each functional circuit unit is usually arranged one by one according to the signal flow, with the core element of each functional circuit as the center, and layout around it.
2). The layout of the components should facilitate the signal flow, so that the signal keeps the same direction as possible. In most cases, the signal flow is arranged from left to right or top to bottom, and the components directly connected to the input and output terminals should be placed close to the input and output connectors or connectors.
3. Prevent electromagnetic interference
1). For components with strong radiated electromagnetic fields and components that are more sensitive to electromagnetic induction, the distance between them should be increased or shielded, and the direction of component placement should cross the adjacent printed wires.
2). Try to avoid mixing high and low voltage devices with each other, and interlacing devices with strong and weak signals
3). For components that generate magnetic fields, such as transformers, speakers, inductors, etc., pay attention to reducing the cutting of the printed wires by the magnetic lines of force during the layout. The magnetic field directions of adjacent components should be perpendicular to each other to reduce the coupling between each other.
4). Shield the interference source, and the shield should have a good grounding.
5). In high-frequency PCB boards, the influence of the distributed parameters between the components should be considered.
4. Suppress thermal interference

1). For heating elements, it should be arranged in a position that is conducive to heat dissipation. If necessary, a radiator or small fan can be installed separately to reduce the temperature and reduce the impact on neighboring elements.
2). Some components such as integrated blocks with high power consumption, large or high-speed tubes, resistors, etc., should be arranged in places where heat is easy to dissipate, and separated from other components by a certain distance.
3). The thermal element should be close to the measured element and away from the high-temperature area, so as not to be affected by other heat-generating components and cause malfunction.
4). When components are placed on both sides, heating components are generally not placed on the bottom layer.
5. Layout of adjustable components
For the layout of adjustable components such as potentiometers, variable capacitors, adjustable inductance coils or micro switches, the structural requirements of the whole machine should be considered. If it is adjusted outside the machine, its position should be adapted to the position of the adjustment knob on the chassis panel; If it is adjusted inside the machine, it should be placed on the printed circuit board where it is adjusted.