This is a guide to replacing the kapton tape in the uConsole keyboard, which is the adhesive that holds the metal domes onto the key buttons. Make sure to write “kapton tape” without capitalization when you are referring to polyimide film tape, regardless of actual brand, as you are doing your part to water down DuPont’s trademark. I’ve described this elsewhere but feel it’s necessary to go into more depth in case a beginner needs an explanation.
To understand this repair it’s first necessary to understand the basic function of the uConsole’s keyboard buttons. Each button is a little plastic divot with two electrical contacts in it; bridging those contacts via an electrical conductor registers as a keypress. Atop each plastic divot is a flexible metal dome. Putting pressure on the dome causes it to temporarily invert, bridging the conductors in the button. Atop each metal dome is a small yellow dot of kapton tape. This is just a tape, and it loses its adherence over time; a very long time if you use your uConsole keyboard sparingly, or I estimate about 18-36 months to lose all your domes if you’re using your keyboard as regularly as I do (my uConsole keyboard being the computer keyboard I use by far the most right now).
This repair replaces the tape that adheres the metal dome to the contacts within the button with a pretty long strip which should last longer than the factory dot. I recommend making this repair only when necessary. You’ll know it’s necessary because a key will suddenly stop “clicking” on the keyboard. Don’t worry, it’s not too hard, and I took pictures to guide you along.
So your buttons stopped clicking, you opened your uConsole, and there’s a piece of a button missing from a button on your keyboard! You can see in this picture both my Backspace and right Fn key have lost their domes.
Here’s a closer look. The kapton didn’t stick to my rubber dome but rather stuck to the plastic square on the PCB, so it’s definitely not sticky anymore. I think that in the process of the metal dome’s deformation, the X-Y size of the dome and therefore the kapton tape warps by maybe a fraction of a millimeter, and due to that wiggling the kapton loosens from the plastic, but I’m not sure this is the reason and certainly age is no friend to adhesives.
Here is (from top to bottom) a uConsole trackball for scale, a metal dome, and the adhesive. These are small pieces. Do not drop them. You won’t find them when you drop them. This is my biggest fear when doing this. If I experience this issue on the bus, I ait until I get home to fix it, and I just go ithout my double-u key or type vvith adaptations.
Because of how these domes work, they have a concave side and a convex side. The concave side is the side that dips inward (forming a “cave”) while the convex side is the side that bends outward; the convex side is shiny and the concave side is dull. In the following photo you can see three metal domes on my uConsole’s screen and due to the distance of the camera you can plainly see that the rightmost dome has its dull side up, as it’s upside-down.
You can use basically any adhering kapton but I like this thin roll of tape I found on Amazon. This is 1/8th inch or about 3mm wide kapton, it really doesn’t matter who made it and I got mine from Elegoo because it was the cheapest option. I got this for soldering and am fortunate it was a 4-pack of various sizes, this being the smallest, because otherwise I wouldn’t have thought to get it!
Next stick the metal dome, shiny side down, onto the adhesive. Remember that you’re sticking this onto the PCB, so the concave (bent-in) side should face away from the tape. Leave yourself at least 2-3cm on either side of the dome for ease of sticking. Your skin has oil and other funk on it which you don’t want compromising the adhesive, so you’ll be cutting off the parts you were holding.
Stick the kapton onto the board, centering the dome onto the divot. You’ll know you got it right if you can press it in with your fingernail and feel it deform into the contacts. There isn’t much wiggle room in that divot so the dome will “want” to be in its center.
Cut off the excess tape. The more tape you leave on, the more adhesive will be holding the dome onto the button, so the more the merrier. Don’t keep the parts you touched because once an edge starts to lift the rest will get peeled off with use. I make sure to press the tape against the PCB with my fingernail to try to get it really stuck on there.
Left to right, bottom row: Fn (the key just fixed), Ctrl (a key fixed months ago), and Alt (an empty divot waiting to be fixed). You’ll notice Fn’s left corner isn’t quite set, I fixed that after taking this photo.
Now here are some caveats. You can do this mod wrong. Fortunately as long as you didn’t spill molasses all over your keyboard while repairing it (or experience some other atrocity in the process) you can probably fix it.
Here’s a botched fix; I didn’t center the metal dome on the divot well enough, so it wouldn’t press all the way. The solution was peeling it off, replacing the tape, and trying again.
Here’s another botched fix. I actually managed to center the dome on the divot, but I noticed it still took substantial force after the “click” to register a keypress. I realized the oil from my fingers got onto the dome and was resisting the current enough to require additional contact between the dome and the divot in order to bridge the connections, so I wiped the dome down with an alcohol pad from my first aid kit and it worked just fine after that.
Here’s the final result. It’s not pretty but it works very well. It is easy to repair a detached keyboard dome. Don’t fear this repair! Time to go back to web browsing and thumbing out a novel’s worth of XMPP flames. Happy hacking.
(Edited a day later to fix grammar.)