AIBOU KAKASHI

EMI test will be
(1) Radiation
    Most of the time, we need to deal with class A requirement
    The watched frequency WINDOW is from 30MHz ~ 1GHz.
    Make sure all the trace are well terminated. You can measure the waveform
    using scope. For those signals has overshooting or undershooting, the PCBA is
    suffering from noise radiated.
   
    In PCB layout, looping in the signal is forbidden. try another placement
    to avoid the circular trace.
   
    Adding serial damping resistor in the high current trace will always help
   
    Make sure leave some capacitor between Signal Ground and Framing ground.
   
   
    You might have chance to deal with Class B.
    My suggestion is to have some consulting service from other company.
    Make sure clock will never go through a moat.
   

(2) Conduction
(2a) Power line
    Most of the time, this is heavily on the power side.
    The measurement is taken by connecting the power cable to a listener.
    You can treat the listener as the noise coulper.
    Any noise from the power will be picked up by listener.
    Remember, those noise are not radiated will be conducted to the power.
    The watched frequency WINDOW is from 150kHz ~ 30MHz.
    Most of the noise will be the harmonics of the PWM clock.
    If the DC/DC runs at 250kHz, then n x 250kHz will be the peak noise.
    The noise floor is also a problem. Bad layout or poor grounding will also
    has bad influence.
    So make sure good filters are put in the power I/P stage and O/P stage.
    For lower voltage, try low ESR capacitor.
   
(2b) ISN
    SOmetimes it will be required to have ISN conduction test if there are
    RJ-45 or RJ-11 jack on the equipment. Putting common choke at the interface will
    help a lot. Most of the time, good isolation to noise source will also help.