A while ago I came up with an idea for a project that seemed to require a flexible LED matrix. I could not find any comerically available, and even flexible LCDs aren’t nearly as common as I would expect. Getting a custom flexiable PCB created is possible, but pretty expensive and not exactly easy. Seeing as a LED matrix is a pretty simple circuit I started looking around for a way to make something at home.
Now the ‘correct’ way to go about this would be to go the route of a printed board like this Instructable lays out. Again for this project I really didn’t want to invest that much time or money. I tried mounting SMD LEDs to multi-conductor ribbon used for e-textiles, that kinda worked, but the constant melting of the cloth started to get annoying.
Eventully what I found worked pretty good for quick and dirty conductors is copper flashing from the hardware store. (yes the stuff meant for your roof) This material has copper on one side, then a plastic backing that hides the sticky back of the copper.
What I did was to take a piece of copper twice the size that I need, and remove the backing on half of it. Then fold it over onto its self.
Once I had copper sandwich all made up and trimmed to look sort of square, I removed a border around one side to be sure the sides don’t short together on the edge.
Now I have bascically two pieces of copper separated by a thin sheet of plastic. To make traces all I did was to cut away copper to make isolated traces for the LEDs to sit onto. To make a ‘via’ after removing some copper, I also cut away the plastic leaving the exposed copper from the reverse side. Since the back side is covered with the glue used to hold it to the plastic I removed that with some rubbing alcohol.
This is no replacement for ‘real’ flex PCBs or even doing it right with Pyralux and echent, it worked for what I wanted. I am tempted to try and etch the copper but I have a feeling it is too thick for that.