Flexible circuits have their uses in many applications but the fastest growing application is in wearable electronics. I was originally interested in making a flexible circuit to be fixed to the circumference of an acrylic disc, so after browsing instructables I came across a very good instuctable that used a substance called "Pyralux". The instructable can be found here: https://www.instructables.com/id/DIY-Flexible-Print...
However, I soon discovered that living in the UK meant that getting hold of Pyralux was very expensive! but after realising the Pyralux is simple copper coated Kapton Tape, I decided to try an make my own Pyralux.
The DIY Pyralux is made from Kapton tape, which is a polyimide plastic capable of withstanding high temperatures, and copper tape, often sold as "Slug repelling tape". Both these items had a combined price well under the cost of shipping a piece of real Pyralux to the UK.
The process is super simple and I was able to make a working LED bracelet in just a few minutes.
Step 1: DIY Pyralux
I first stuck the Kapton Tape to a piece of acrylic for easy removal after. I ended up layering 3 pieces of Kapton on top of each other to give the circuit some rigidity and thickness. Kapton tape is actually very thin. I found it easier to use a cardboard tube to roll the tape on. Air bubbles can be annoying but didn't seem to hinder function too much, but still best to try and avoid them.
I next peeled and added a single layer of the copper tape and that's all there is to it.
To make a simple circuit, I used a craft knife to cut a design and then peeled away the unnecessary copper. I was also able to flatten the DIY Pyralux enough to machine a design and make a working circuit using LEDs and a coin battery. Soldering onto the copper was simple and didn't give me any problems. The final test would be to chemically develop a circuit with etchant solution. I'm not sure if the tape adhesive would withstand chemical development but I didn't have any etchant to test this.
And that's about all there is to it! If any one wants to test this with a chemical etchant than I'd be eager to hear how it turned out. :D