Prototyping Membrane Keys

Jim Fouch

When cleaning out a lab for one of my clients, I came across this neat Membrane switch PCB. I have done some searching, but have not found anything on the inetrnet.

Was wondering if anyone knows where this material can be found?

My client said you used to be able to but this in a large PCB. To use you simply cut out a grid of buttons and just solder to the back side and label the front and wola....you have a membrane keypad.

LoopyByteloose

I am still wondering when the paper soda straw disappeared. It was environmentally superior to the plastic ones and it seems to me that it should be revived.

I suspect these are another product that just faded away as commerce marched on. In general with technology you have to have people buy 10,000 units at a time to make any real money. Hobbyist never want more than a dozen and rarely more than 3 at a time.

These days I am fearing radial resistors may one day just not be around. And I am wondering whatever happened to a simple coffee pot as well.

Do you remember those big tuning capacitors inside radios that used air for insulation and a 'tank circuit' for tuning. It is all done in solid-state now.

Computer Geek 101

I have made some using printable transparencies and shielding paint. You print your buttons, coat the back with the shielding paint. Then make a second plastic layer with boxes cut out where the buttons are located. Glue the plastic to the circuit board grids. I have some for my time clock its used buy 30 people 4 times a day for 2 years now without a failure.

Jim Fouch

I've thought about using my laser engraver to create my own membrane type pushbuttons. I now have an LPKF PCB Milling machine so making the button contact points should be pretty easy.

Computer Geek 101

For the pcb, I made interlaced "fingers" of copper. It seems to work well. I used a nickel shielding paint for the plastic buttons. The paint isnt cheap but it lasts forever.

http://www.mgchemicals.com/products/841.html?PHPSESSID=cd057ef19f063b3eaa7bc03965e0f40f

Gadgetman

Loopy Byteloose wrote: »

I am still wondering when the paper soda straw disappeared. It was environmentally superior to the plastic ones and it seems to me that it should be revived.

Actually, you can still get them, but there's only one manufacturer left.
I know this because of the P.A.R.I.S (Paper Aeroplane Released Into Space) project at The Register.

http://www.theregister.co.uk/science/paris/

Phil Pilgrim (PhiPi)

You can also use metal snap domes under the membrane. The PCB layout for each switch, rather than being interdigitated, consists of two concentric circles, the inner one filled and connected with a via to the bottom of the board.

-Phil