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Capacitance sensing pads

autodeskguest

I'm trying to make some symbols to use as capacitive sensing buttons for use

with a Cypress PSoC Capsense chip. The Cypress application note (AN2292)

says to fill ground around the pads. I can't figure out how to create a

buffer area to keep the polygon from filling right over the pads. Any ideas?

 

 

 

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  • LGR wrote:

    I guess I wasn't clear. The symbol consists of a through-hole pad (which is

    what the device connects to on the bottom layer), and a polygon around it.

    The polygon has to be made in the top layer only, because that's where the

    touch sensing happens. I can't make it with layer 17, because that would

    create polygons on both top and bottom. For the buttons, I suppose I could

    distort an SMD, but I also need to create W-shaped elements for the

    "slider". If you're curious, here's the application note:

     

    http://download.cypress.com.edgesuite.net/design_resources/application_notes/contents/capacitance_sensing___layout_guidelines_for_psoc_capsense___an2292_12.pdf

     

     

    Avoid top posting in newsgroups- the threads don't make sense that way.

     

     

     

    OK I guess it wasn't too clear to me. But here's my second guess.  You

    actually want to make a package in the library?  The libraries do not handle

    polygons well.

     

    My first guess was that you were just going to draw this straight on the

    PCB, which is where polygons of different rank make drawing this relatively

    straightforward.  If you want more than one pad, then use copy-cut and paste

    for the polygons

     

     

    cheers

     

    David

     

Reply

  • LGR wrote:

    I guess I wasn't clear. The symbol consists of a through-hole pad (which is

    what the device connects to on the bottom layer), and a polygon around it.

    The polygon has to be made in the top layer only, because that's where the

    touch sensing happens. I can't make it with layer 17, because that would

    create polygons on both top and bottom. For the buttons, I suppose I could

    distort an SMD, but I also need to create W-shaped elements for the

    "slider". If you're curious, here's the application note:

     

    http://download.cypress.com.edgesuite.net/design_resources/application_notes/contents/capacitance_sensing___layout_guidelines_for_psoc_capsense___an2292_12.pdf

     

     

    Avoid top posting in newsgroups- the threads don't make sense that way.

     

     

     

    OK I guess it wasn't too clear to me. But here's my second guess.  You

    actually want to make a package in the library?  The libraries do not handle

    polygons well.

     

    My first guess was that you were just going to draw this straight on the

    PCB, which is where polygons of different rank make drawing this relatively

    straightforward.  If you want more than one pad, then use copy-cut and paste

    for the polygons

     

     

    cheers

     

    David

     

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