via「Google News search」：https://www.edn.com/design/power-management/4461941/PCB-design-for-low-EMI-DC-DC-converters

It is best to use a two-side assembled PCB with at least four layers, where the DC/DC circuit and filter components are placed on opposite sides of the board. At least one inner layer should be solid GND to minimize cross-coupling from the noise source into the filter circuits.
In systems where the DC/DC circuit must be placed very close to the connector, effective shielding must be considered early in the design process. Thermally necessary heatsinks can sometimes be utilized for shielding. Ideally, the inductor, the DC/DC IC with power MOSFETs, and its decoupling capacitors are all located under the shield.
PCB layout guidelines
In a step-down converter, the main field sources are:
High di/dt loop (hot loop), formed by the two power switches and CIN, which radiates wide-band magnetic fields
SW node between power FETs and the inductor, with strong E-field radiation
The inductor, which radiates E-fields and H-fields
AC-magnetic fields are shielded by solid metal areas that allow the induction of eddy currents. Due to its high conductivity, copper is very effective. Any conductor in the path of the potential difference that returns to a fixed potential on the PCB will effectively shield E-field radiation.
Any high di/dt loop radiates H-fields proportional to the loop area and current amplitude. Place the input capacitor close to the two power switches with a low-impedance connection to minimize the antenna loop area.


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