rubber button fixes?

Discussion in 'General Electronics Chat' started by circuitfella11, May 10, 2013.

  1. circuitfella11

    Thread Starter Member

    May 10, 2013
    56
    5
    I have a machine that has a control pad that uses rubber buttons, this are the ones that have a bit of conductive material on the end of it and it shorts two traces on the PC board.

    One button dont work well if at all. I've cleaned the contact area on the PC board and the button. I also tested the contact pad and its fine.

    I think I has seen kits to fix this somewhere, but I'm not sure if its just something to clean the contact pad.

    I can't even Google it right because I can't even come up with the right term for this button.

    thanks in advance
     
  2. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    What have you cleaned it with... ± 200 proof denatured alcohol, - Methanol = or " everclear " ethanol work best...
     
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  3. MrChips

    Moderator

    Oct 2, 2009
    12,449
    3,363
  4. absf

    Senior Member

    Dec 29, 2010
    1,493
    372
    I have come across this type of problem many times especially on music keyboards. Normally I would just order the rubber membrance and the PCB as the keyboard contacts are hard to get access to. I have to repeatedly repair the rubber contacts, mount it, then test and if it doesnt work. The whole process has to be repeated again.

    If your rubber contact is easy to get access to, you may try with the repairing carbon glue or even make your own as listed here:

    http://www.2spi.com/catalog/spec_prep/cond_paints3.php

    http://www.instructables.com/id/Conductive-Glue-And-Conductive-Thread-Make-an-LED/step1/Make-Conductive-Glue-Conductive-Paint-and-Conduc/

    But be warned that I have came across one case where the carbon surface looked fine but somehow the contact doesnt make at all when the rubber is pressed. It was found that the carbon was not making properly with the copper trace on the PCB. This was due to factory fault, as they didnt clean the PCB properly before coating the carbon glue. I have to change the PCB as there is no way for me to repair it.

    Allen
     
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  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,061
    3,826
    You can try polishing the PCB pads with a high quality pencil eraser. Depending on how deep (Thick) the rubber conductive pad is, you can try slicing a 1/2 mm layer and expose new conductive particles.

    Another option is to melt some silver solder onto the PCB contacts. unlike copper oxide, silver oxide is conductive.
     
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