Capacitive touch keypad-PCB layout in eagle

Discussion in 'The Projects Forum' started by pharmerlary, Mar 28, 2014.

  1. pharmerlary

    Thread Starter New Member

    Sep 1, 2013
    Hello, I'm designing a PCB for a capacitive touch sensing keypad using eagle. The sensor I'm using is Atmel's AT42QT1110-AU IC.
    I've read a number of guides on designing capacitive touch sensors and I'm aware that component placement, trace length and routing are all important in creating a reliable "Product".

    My questions: Are the components too close? With the traces so close together will the capacitive loading reduce the sensitivity too much? Are the signal traces too close to the sense traces?

    Unfortunately I'm using a single layer board.

    I wasn't sure how to add pictures in text (without link) but schematic and board (as .zip) are attached.
    Also, the electrodes are 8 mm across although they appear larger with whatever layer settings are on (I'm new to eagle) and they will have a small hole drilled in the center for led back-lighting.

    Touch sensor Datasheet:

    Design guidelines

    Any suggestions on component placement/trace routing (ect.) would be greatly appreciated!


    (this is my first post so hopefully this is in the right place)
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Then you should also be aware that stages of prototyping and testing are very important in making a reliable product. :)

    You really need to make one and test it. And maybe rinse and repeat.

    Especially if it is a layout-fussy capacitive component you have not worked with before.

    Sorry if that's not what you wanted to hear.
  3. pharmerlary

    Thread Starter New Member

    Sep 1, 2013
    Alright, thanks for the response I'll give it a try.
  4. nqmartin

    New Member

    Aug 12, 2015
    I just found this thread and was curious if your design worked.