While working on how to make a grid to give electric shocks to flies(see last log), I  came up with the idea of etching a pattern of interdigitated arrays on a piece of copper tape. I had originally intended to cut out thin strips and create the same pattern but I thought of giving this a try. I wasn't very hopeful as I had never etched PCBs before. I ordered a copper tape online and while waiting for it to arrive I made some ferric chloride by dissolving iron nails in dil HCl and then oxidizing it with H2O2.

The copper tape was really good and easy to work with. I pasted it on a transparent plastic film. I printed a schematic of the array on glossy paper using a laser jet printer. The toner transfer was performed using acetone as I could not heat it. It was not very effective but okay-ish so for the second attempt I went a little adventurous and also ironed it at the lowest temp setting. The combination of acetone and iron gave really nice results. If someone is experienced then I think it is possible to get really thin tracks.

The possibilities for making DIY wearables using this technique are immense.

Copper tape(single sided)

Interdigitated array printable image.(made using MS Paint)

6cm x 5cm piece of copper tape on transparent plastic sheet.

After the toner transfer. The small imperfections, a result of either my incompetence or the irregularities of the tape surface or a combination of both,  were managed by using a permanent marker.

The etching using FeCl3.

The results................................................

Due to the sticky adhesive on the tape some of the toner was a pain to remove. But the nice thing is that the glue is super strong and resistant to alcohol and acetone.