copper pour under the transformer

[jack_pcb]

Hi ,

I am using transformer at ethernet section and as per many other designs i have used transfomr , here while doing copper pour of GND , we give the no copper area under Transformer .
So no copper under the transformer , can tell why we do so , .Primary and Secondary of TR are coupled so there should not be issue of isolation .
pls guide .

Thanks in advance

 

[kabaleevisu]

Hi Jack,
Transformer is a EMI component.if you applying copper under that Transformer it might affect near by component.better remove copper under the transformer.

 

[jack_pcb]

thanks for the reply .
How copper affect the Tr?

 

[kabaleevisu]

Hi Jack,
if you applied copper under the transformer which magnetic field couple with under the copper.

 

[marce]

Transformers and Inductors have as stated strong magnetic fields, its how they work, this can couple to traces and the ground plane adding noise or coupling HF noise from one side of the transformer/Inductor via the ground to the quiet side. This is the main reason for the Ethernet interface is to avoid any noise picked up by the often very long cables...