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On lots of electronic devices, such as this Korg drummachine/sampler,

enter image description here

there are some soft rubber push buttons.

What are they called? (I'm looking for the most common name, so I'll can find them easily on eBay or any electronic-parts-shop)

How do they work? (and if on topic, are such rectangle pushbuttons easy available?)

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  • \$\begingroup\$ I think "membrane switch" is a term sometimes used. \$\endgroup\$ – Hot Licks Mar 11 '15 at 17:47
  • \$\begingroup\$ @HotLicks A membrane switch is a different thing. Membrane switch has metal domes in it that do the switching and give the tactile feel. \$\endgroup\$ – Nick Alexeev Mar 11 '15 at 18:38
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It's a silicone rubber keypad. They're usually custom-made for the application (MOQ in the thousands or more if a mold has to be made).

http://www.interfacetech.com.cn/Upload/image/vit-r-0018.jpg

They require a matching PCB that is either gold-plated or printed with a carbon paint in order to form the key patterns. The rubber keys have a conductive silicone bit molded into the back of the keys that bridges the PCB interdigitated pattern so that the switch is closed (the resistance is not nearly as low as with a switch that has metal contacts, but plenty good enough for a microcontroller to detect). The buckling of the key gives a tactile feel that is appropriate. Sealing against the environment (water, finger oils etc.) is not great, but acceptable for many applications.

http://www.haeusermann.at/sites/default/files/styles/content_image_lightbox/public/articleimages/capacitive_keyboards.jpg

Excellent choice if you're making a large quantity of a product, not so practical if you're only making a few hundred pieces or fewer.

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  • \$\begingroup\$ Thanks a lot for this answer @SpehroPefhany! I definetely haven't a large quantity to produce, but only a few units. Can we find push buttons (in component shop) like this? i.e. imitating the same button feeling (which is really nice and comfortable thanks to the rubber)? \$\endgroup\$ – Basj Mar 11 '15 at 15:22
  • \$\begingroup\$ You need to design and make a PCB to match it, so it's not just a matter of buying a component. You may be able to find individual keys as shown in the top photo above (I have a bag of 1000 or so kicking around for prototypes- quite different from what you want), but not sure the usual disties would carry them. \$\endgroup\$ – Spehro Pefhany Mar 11 '15 at 15:26
  • \$\begingroup\$ "Sealing against the environment (water, finger oils etc.) is not great, but acceptable for many applications." - I've seen products that are completely sealed, with silicone all the way around. There are some computer keyboards like this available for example. \$\endgroup\$ – Random832 Mar 11 '15 at 16:44
  • \$\begingroup\$ @SpehroPefhany I hoped there existed such buttons, but without having to make a specific PCB with this "snake". I hoped there exists such button "ready-to-use" in a enclosure with 2 (or 3, 4) pins, ready to be mounted on a PCB, like this ottoexcellence.com/assets/item/regular/P1-3_Pushbutton.jpg but with rubber... Do you think this exists? \$\endgroup\$ – Basj Mar 11 '15 at 18:37
  • \$\begingroup\$ @Basj You can find complete keyboards (in typical fixed layouts such as number pad), but I don't think you'll easily find individual complete switches (as opposed to buttons). Of course I could be wrong. \$\endgroup\$ – Spehro Pefhany Mar 11 '15 at 18:57

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