[SOLVED] what is the use of Solid trace surrounding the PCB boundary of Power supply ?

Hi all ,

I was looking at some artwork of the Power supply where i found the solid trace surrounding the boundaries of PCB . That solid trace was connected to the EARTH point of the Power supply Connector .

I just want to know the purposee of that solid Trace and why is it required ???


Regards !!

V V

It may be a Faraday ring, a place for E-field noise to go if it
wants.

It may be just a piece of art, a harmless border to the
layout section (better for someone to run too close to
ground, than too close to a high voltage switch node -
where relaxed rules might be needed but someone might
forget).

It may be used to absorb any electrical noise during circuit operation, so by giving such a closed surrounding earth connection most of the noise can be suppressed.

I also found some I/O modules with the same isolation but ( Hatched type & not solid traces like in power supply ) at the boundaries .

It might be for EMI reduction like Faraday Cage or Farday ring as stated above .

Still have doubt about use of HATCHED ISOLATION .
Any useful input about HATCHED ISOLATION would be of great help .

Regards !!

V V

vikasveshan said:

Hi all ,

I was looking at some artwork of the Power supply where i found the solid trace surrounding the boundaries of PCB . That solid trace was connected to the EARTH point of the Power supply Connector .

I just want to know the purposee of that solid Trace and why is it required ???


Regards !!

V V

Click to expand...

One possibility is that it relates to electrical safety and isolation requirements in particular creepage and clearance. If the power supply is mounted within a metal chassis where the Earth Bonding on the chassis may not be guaranteed then the designer would have had to allow 6mm to 8mm clearance for high voltage tracks at the edge of the PCB.

By placing a track around the periphery of the PCB and connecting that directly to the Earth pin of the power supply connector such requirements will have been relaxed. The designer would still have had to ensure minimum spacing depending on the voltages he was dealing with in the circuit itself and there may be a minimum requirement of 1mm HT to Earth anyway.

A 2mm track with 1mm clearance would waste 3mm of board as opposed to the previous 6mm to 8mm which will be significant if space was tight. The track should be dimensioned to cope with fault current.

Genome

It helps little for EMI reduction in my experiments. It can reduce noise.