5 Replies Latest reply on Nov 6, 2018 6:40 AM by ari.fox_3842691

    PCB layer stack up and routing for lots of capacitive touch buttons and surface mount LEDs

    m_shihab_2337616

      Hi,

         

      I am working on a design which has about 30 capacitive buttons. Each button needs an LED for backlight. 

         

      I know that recommended approach in this scenario is to use back-firing LEDs but there are many other components in the design that need to be placed on the bottom side of PCB. 

         

      So I was wondering, Can I place surface mount LEDs (e.g., 0603 size) at the center of sensor electrodes?

         

       

         

      My other question is: What layer stack up should I choose?

         

      There will be sensor electrodes and LEDs only on the top most layer. The second layer can be used for sensor traces. Plus I need at least two layers for digital signals. From what I have read so far, I need a hatched ground plane between sensor signal layers and digital signal layers.

         

      so should I select a six-layer stack up? and what signal-plane configuration?

         

       

         

      Regards