2 Replies Latest reply on Feb 2, 2014 8:17 AM by hgibbons

    RF Shield clearence violation




      I have a design where I use some RF shield boxes.

      The footprint for the box is a closed rectangle with a 1.5mm wide line. I have made a single pad i one corner, and combined it with 1.5mm wide copper strips along the edges of the rectangle.


      The problem is that I can place the outline of the shielded box on my pcb, and I can place the components of the circuits that need to go into the box in Layout, but when I switch to Router to lay some tracks, I get a clearence violation when I select the pads of the components inside the box.


      Is there a way to define the area inside the rectange as a valid place to have components? Or is there a workaround?

      Should the RF shield footprint have been made differently?




      Peter Karlsen

        • 1. Re: RF Shield clearence violation

          Interesting.  This same topic was brought up by another user on another forum recently.


          So it sounds like you've defined a component for your shield box (a neat idea).  Unfortunately PADS doesn't deal well with components mounted under components; it considers it a body to body clearance violation.  This might be a popular topic for Bright Ideas, to support 'components less than xxx mils under component yy'.  These seems like a natural extension of the 'geometry.height' attribute to apply it to items on the PCB as well as items off the PCB.  I'll vote for it!


          One workaround may be to define the RF shield as a 2D Line item instead of a part and then define a height keepout where you place it (I believe this will have to be done manually as you can't define the keepout in the library).  The BOM gets tricky then.

          • 2. Re: RF Shield clearence violation

            This is a common thing that users want to do.  Reasons for it include defining footprints for mezzanine boards and as you say RF shields.


            I think the way to do it is for Layout to allow the user to define a placement exception area within the part.