Mounting MA702 and magnet on opposite sides of PCB

Motor Drivers/Sensors
1

Is it possible to mount the encoder magnet on the opposite side of the PCB where the MA7xx sensor is located?

In my trials with MA702, I have successfully used the sensor with this configuration. In addition, the sensor-magnet distance is in accordance with application note “Selecting the Right Magnet for the MagAlpha in End-of-Shaft Mounting”. The PCB in question does not have copper layers between the sensor and magnet, only the traces to the IC pads.

My understanding is that copper and the FR material used in the PCB have negligible magnetic permeability and should not affect the sensor magnet field.

Is this understanding correct? Is such mounting possible?

2

Hi there,
Yes, this type of arrangement is possible, what really matters in the end is that there is enough magnetic field reaching the sensor.
Of course the minimum distance is imposed by the thickness of the PCB, so it puts some constraints on the design, that you have to take into account when chosing the magnet (you can use our online simulation tool for that). But as long as the PCB is not acting as a magnetic shield (due to copper plane), then it is fine.
Best regards,