The layout of components on a PCB board is to move the components to an appropriate position according to the size of components, the mutual interference between components, the thermal effect of components and the logical relationship between components.The layout of components is very important, which is the key to the success of circuit board layout, the general principles of layout are as follows.
（1）According to the layout principle of "first big then small, first difficult then easy", that is, the important unit circuit and core components should be layout preferentially.
（2）The layout shall refer to the principle block diagram and arrange the main components from left to right or from top to bottom according to the main signal flow rule of the single board.
（3）Layout should meet below requirement:The overall connection line should be as short as possible, and the key signal line should be the shortest.High-voltage and high-current signals should be completely separated from low-voltage and low-current signals.Separate analog signals from digital signals;High frequency signal is separated from low frequency signal;High frequency components should be at large interval.
（4）For same structure circuits, "symmetrical" standard layout should be adopted as far as possible.
(5)Optimize layout according to standards of uniform distribution、balance of gravity and beautiful layout
(6)Heating components should be evenly distributed to facilitate the heat dissipation of the single board and the whole machine. Except temperature sensitive components other temperature detection components should be kept away from components with high heat dissipation.
(7)The array of components should be convenient for debugging and maintenance, that is, large components cannot be placed around small components, and there should be enough space around the components to be debugged.
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