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conductive rubber glue?

Discussion in 'Electronic Design' started by jtaylor, Dec 21, 2004.

  1. jtaylor

    jtaylor Guest

    The more I think about this the longer a shot it appears likely to be, but
    here goes anyway:

    I have a car radio with button switches that don't work. Buttons for bands,
    memories, that sort of thing.

    The switches are a plastic button, a printed circuit with two traces, and a
    kind of black rubber doughnut with a tit in the middle. The tit sticks out
    a bit more from the bottom of the assemble, so it hits one pc board trace,
    the joint between the tit and the ring flexes, then the ring hits the other
    pc trace, and the switch is closed.

    Many of these little rubber things have broken where the tit is joined to
    the dougnut. I'm off to another car radio repair place tomorrow - at the
    really good electronics place that I go to first the guy just shook his
    head, so I don't have much hope of finding new bits. This radio is old and
    foreign.

    Is there a conductive flexible rubber glue?
     
  2. Active8

    Active8 Guest

    I got some Nickel Coat (Kote?) from Bainsville Electronics,
    Baltimore. Get that or whatever they have.
     
  3. Jerry G.

    Jerry G. Guest

    There is something called a remote control kit for fixing the buttons. This
    is an adhesive conductive coating that is painted on to the buttons to make
    them conductive again. It is formulated to stick to the type of silicon
    rubber that the pad buttons are made out of. Regular contact cement, and the
    others will not stick to the pad buttons.

    Many of the electronic parts suppliers can supply this kit for servicing the
    pad buttons.

    --

    Jerry G.
    =====

    The more I think about this the longer a shot it appears likely to be, but
    here goes anyway:

    I have a car radio with button switches that don't work. Buttons for bands,
    memories, that sort of thing.

    The switches are a plastic button, a printed circuit with two traces, and a
    kind of black rubber doughnut with a tit in the middle. The tit sticks out
    a bit more from the bottom of the assemble, so it hits one pc board trace,
    the joint between the tit and the ring flexes, then the ring hits the other
    pc trace, and the switch is closed.

    Many of these little rubber things have broken where the tit is joined to
    the dougnut. I'm off to another car radio repair place tomorrow - at the
    really good electronics place that I go to first the guy just shook his
    head, so I don't have much hope of finding new bits. This radio is old and
    foreign.

    Is there a conductive flexible rubber glue?
     
  4. Steve Dunbar

    Steve Dunbar Guest

    jtaylor wrote:

    ....

    See <http://www.sandman.com/rubberb.html>.
     
  5. Richard H.

    Richard H. Guest

    Another option: Aluminum tape. Used for furnace ductwork; purchased at
    the hardware store in a roll like duct tape. It's thin metal foil with
    strong adhesive on the back. A great fix for membrane keys that've lost
    their conductivity.

    Richard
     
  6. Ralph Barone

    Ralph Barone Guest

  7. Guy Macon

    Guy Macon Guest

    Aluminum is a poor choice. When exposed to air it forms a
    non-conductive layer of aluminum oxide. Tin or Gold-plated
    or even Copper foil would work far better.
     
  8. James Sweet

    James Sweet Guest

    That tape seems to remain pretty shiny over time, it may not be pure
    aluminum.
     
  9. Si Ballenger

    Si Ballenger Guest

    Sounds good. So where can these adhesive backed foils be easily
    purchased at a reasonable price?
     
  10. NSM

    NSM Guest

    |
    | | >
    | > Richard H. wrote:
    | >
    | > >Another option: Aluminum tape. Used for furnace ductwork; purchased at
    | > >the hardware store in a roll like duct tape. It's thin metal foil with
    | > >strong adhesive on the back. A great fix for membrane keys that've
    lost
    | > >their conductivity.
    | >
    | > Aluminum is a poor choice. When exposed to air it forms a
    | > non-conductive layer of aluminum oxide. Tin or Gold-plated
    | > or even Copper foil would work far better.
    |
    | That tape seems to remain pretty shiny over time, it may not be pure
    | aluminium.

    I believe it has a coating of lacquer over a VERY thin film of aluminium, so
    that's another reason to avoid it.

    N
     
  11. NSM

    NSM Guest

    | On Tue, 21 Dec 2004 18:01:20 +0000, Guy Macon
    |
    | >
    | >Richard H. wrote:
    | >
    | >>Another option: Aluminum tape. Used for furnace ductwork; purchased at
    | >>the hardware store in a roll like duct tape. It's thin metal foil with
    | >>strong adhesive on the back. A great fix for membrane keys that've lost
    | >>their conductivity.
    | >
    | >Aluminum is a poor choice. When exposed to air it forms a
    | >non-conductive layer of aluminum oxide. Tin or Gold-plated
    | >or even Copper foil would work far better.
    |
    | Sounds good. So where can these adhesive backed foils be easily
    | purchased at a reasonable price?

    Copper foil is used for crafts but may be too thick.

    N
     
  12. I read in sci.electronics.design that James Sweet
    What happens is that an oxide film forms almost instantaneously, but it
    is exceedingly thin and has a very low breakdown voltage. So unless you
    want a good contact for millivolt-level signals, aluminium will work
    reasonably well. But gold is better, and consequently costs more.
     
  13. James Sweet

    James Sweet Guest

    And shielding, sticky copper tape is readily available.

    I find though that those keypads don't really lose conductivity, they simply
    become saturated with skin oils. A good scrub of the membrane and circuit
    board with liquid dish detergent has fixed every one I've encountered yet.
     
  14. Richard H.

    Richard H. Guest

    Very possible it is tin, considering it's been aging in my shop for
    about 10 years before I put it to use... and still shiny.
     
  15. NSM

    NSM Guest

    | Guy Macon wrote:
    | > Aluminum is a poor choice. When exposed to air it
    | > forms a non-conductive layer of aluminum oxide.
    | > Tin or Gold-plated or even Copper foil would work
    | > far better.
    |
    | Very possible it is tin, considering it's been aging in my shop for
    | about 10 years before I put it to use... and still shiny.

    It may be vacuum deposited aluminium with lacquer over it.

    N
     
  16. DoN. Nichols

    DoN. Nichols Guest

    [ ... ]
    Hmm ... check your local electronics hobby store for the kind of
    tape used to build up "printed circuit" boards, instead of the more
    common etching away of the unwanted copper from a fully copper clad
    board.

    Enjoy,
    DoN.
     
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