Whether the Y capacitor is placed before or after the common mode

The capacitance of the board should be placed on the basis of the capacitors. We all know the Y capacitor, and its advantages are recognized by many people, and it is used in many switching power supplies.

So, where is the placement of the Y capacitor before or after the common mode? To prevent interference from coming in, it is better to put it after the common mode; to prevent the interference from running out, it is good to put the Y capacitor outside. Many power supplies directly solder the Y capacitor to the AC input socket.

Different circuits are placed in different locations and should be understood before use.