2 Replies Latest reply on Oct 23, 2018 5:31 PM by user_474444345

    MBR3, Minmum width of shield electrode

    user_474444345

      Hello,

       

      I have 2 questions.

       

      Q1)

      In old type of CapSense Design Guide, the below was recommended. I can not download the document anymore now, So I picked up the picture from Japanese ver.

      In the documentation, the maximum shield width is shown as 1cm. However, there is not described minimum width.

       

      図4-13.シールド電極パターン.png

       

      In other chapter, there is described that Hatch pattern should be 0.17mm trace and 1.143mm grid (25% filling)

      If we can satisfy this condition, can we take any shield electrode width?

       

      Q2)

      How much space is needed between Shield electrode and PCB Ground Plane.

       

      Best regards,

        • 1. Re: MBR3, Minmum width of shield electrode
          brvi

          Dear Takeshi-san,

           

          Kindly note that you need to follow the guidelines as per the newly updated English version of the document which has answers to your questions. The guidelines in the Japanese version of the document is old and needs update.

           

          Please note the following:

          Q1)

           

          1. The shield spread should be within 1 cm as given in the updated design guide.

           

          Refer: http://www.cypress.com/file/46366/download  (MBR3 Capsense Design Guide) - Layout Guidelines for Liquid Tolerance section. Pg no 41

           

          2. There is nothing as such like minimum spread for the shield. The minimum area for shield electrode can be the area remaining on the board after implementing the sensor (ie <1 cm)

           

          Q2)

           

          We don't recommend any PCB ground plane in the same layer of that of the shield or underneath the shield. You need to leave it empty (beyond 1cm spread).

          Refer http://www.cypress.com/file/41076/download  (Getting started with Capsense guide), Shield Electrode Construction for Liquid Tolerance section, Pg no 86.

           

          I hope this answers your questions!

           

          Regards,

          Bragadeesh

          • 2. Re: MBR3, Minmum width of shield electrode
            user_474444345

            Hello Bragaeesh-san,

             

            Thank you very much.

             

            Best regards,