Rubber Keypad problems – liquid… oil… moisture… found inside the buttons. What is it? Where does it come from??

Anyone who has taken apart a few failing TV remotes, cordless phones or other devices with bad buttons has probably run into a curious oily liquid inside the buttons causing the problem. You can clean it up using isopropyl alcohol but the problem returns.

Like most people (including myself) when you first run into this you probably think the liquid is from a drink spill… or humidity… or maybe oil from your hand…  What is it!?!?

Come to find out…
It’s NOT from a spill, finger oil, humidity… or even spit 😉
The liquid found in rubber keypads is left over silicone oil from the manufacturing process when they rubber keypad has not been baked enough…. it’s a gooey center, undercooked rubber keypad!

Cooking those rubber pads takes a lot of time and energy….. and when you can save some time and energy (money) you can lower the cost of your product. Since it can take years for the oils to ooze out of the rubber pad it will never be caught by the development team….. and if lucky, never even cause a problem for the consumer.

I once took several different  new rubber keypads and crushed them overnight in a 3000lb press between two metal plates and a few paper towels…. just to see for myself.  The next day there was a ring of oil around each keypad in the paper,  one much more than the other. I can assure you that stain was not a drink spill, humidity or oil from my hands as I put handled the keypads.

Some rubber keypads have large rubber button contacts and those always have the most trouble with oils. A better keypad design uses a thin rubber keypad and a larger plastic button over the keypad.  Of course if one button is used more you are going to see more problems…. like the channel and volume buttons on the TV remote… or the Answer button on a cordless phone.

The KX-TGA400b phone had… no has, terrible button problems. The keypad is entirely rubber (no plastic key caps)…. and the keypad was produced as cheaply as possible (less baking). This model is famous for the #1 key not working. Being curious as to why the #1 button on a phone would be the first to act up, eventually after looking into it for a while I discovered that the way many people hold the cordless phone was the issue. Their thumb would need to apply more pressure to the top left key just by the way it was held in the hand. A little extra pressure over hundreds of button presses was all it took.

Posted in Button Repair
3 comments on “Rubber Keypad problems – liquid… oil… moisture… found inside the buttons. What is it? Where does it come from??
  1. Carl Tuszynski says:

    This explains everything. I have an Onkyo RC-810M remote with a bad volume up/down button. Over time you would have to press the button harder and harder to make it work. Eventually it quit working. Upon inspection, I noticed clear silicone oil on the circuit board below the button. Again this is a large button, and when you press it hard over time, if it is not fully cooked, you will indeed see oil seeping out. Cleaning up the oil did help for a short time, but it failed again because apparently the tip of the button contains imbeded conductive graphite. If enough of the graphite gets worn or melts away, there will be no electrical contact possible anymore. I agree, poor design or QC. To add insult to injury, mfgr does not offer repair parts. A new remote costs about $80. (Ouch) Good luck with the aluminum foil or the conductive paint fix….. Remember, hardly anything will stick to silicone rubber for any length of time. And if the rubber is indeed under cooked and seeping oil, forget about it. I did get it to work again by replacing the button with another one on the pad that was not in use. Good luck on this one also, surgery on the silicone pad with a group of buttons is tricky. Use a sharp knife and a lot of patience. In the end it did not look pretty, but it is working again, for how long I do not know.

    • Tom Middlebrook says:

      I have used conductive silver paint. After cleaning the silicone button surface, I use a miniature blade screwdriver tip to apply the thinnest layer possible. It works great, but if the silicone pad is still releasing oil, the paint will come loose. Repeat, and call me in the morning.

      • Ben says:

        I tried many different conductive paints and epoxy over the years. They all crack, peel and wear off and end up depositing conductive material between the contacts shorting out a button and locking up the entire keypad. I even experimented with coating the buttons with rubber infused gel super glue, sanding them flat and coating that…. lasted a little longer but still sometimes failed within warranty. Not good enough.

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