pcb using boards and copper tape

[ag123]

i'm thinking about using *copper tape* and perhaps boards (e.g. acrylic) to make PCB for custom keyboards
the copper tapes can be rather easily sourced on amazon, ebay etc
https://www.amazon.com/s?url=search-alias%3Daps&field-keywords=copper+tape

while wandering around the web doing google searches, i found some examples, several of them about paper (or fabric) circuits
https://forum.allaboutcircuits.com/threads/pcb-fabrication-with-copper-tape-matrix-board.83857/
https://learn.sparkfun.com/tutorials/the-great-big-guide-to-paper-circuits
https://core-electronics.com.au/tutorials/using-copper-tape-with-paper-circuits.html

i've seen some examples about diy etching of keyboards e.g.
https://deskthority.net/workshop-f7/hhfox-aka-diy-pcb-t6905.html

as a keyboard is mostly the board and little wires, it would seem that etching away that much copper is pretty wasteful
in addition large keyboards e.g. 104 keys and more would require large PCBs, those large PCBs could be rather expensive and hard to source for

has any one tried successfully to use copper tape to make PCBs for custom keyboards ?
or what are your thoughts about it?

[sinusoid]

Try electroplating.

You can get a very fine layer of copper on almost anything, you specify its thickness on order. There are places that electroplate glass and plastics.

Just make sure you tell them what you're gonna use that for, electroplating non conductive materials often involves an intermediate coating with a conductive material that may resist etching, or require a bath in a different solution to remove.

If you're just about prototyping with clean metallic lines of awesome shininess, try using this instead of the etched tape:
http://elm-chan.org/docs/wire/wiring_e.html

[vvp]

If you're just about prototyping with clean metallic lines of awesome shininess, try using this instead of the etched tape:
http://elm-chan.org/docs/wire/wiring_e.html

+1

Or just etch blank PCBs at home. It is very easy to do especially for one sided PCBs. You can buy a blank PCBs for about $1 per dmē. 200 ml of etchant is about $3. The only other thing you need is an access to black and white laser printer and an iron (toner transfer method). All this is really easy to do at home. Good for feature sizes down to about 0.4 mm.

If you want much better quality then buy blank PCBs with photo-resist applied. Get transparent plastic foils suitable for laser printer (you will print the PCB traces on the foil, around $1 for one foil) and an ultraviolet light (the cheap ones for checking bank notes are ok, maybe $ 10 - 20) and a developer (probably around $1). Good for feature sizes around 0.2 mm.

With the above tools you can etch a PCB in about 2 hours at home. I bet it will cost you less in time than the copper tape. It will be also quicker (for a non-trivial circuit) than the method sinusoid linked. But the magnet wire method is good. I used it myself ... but etching at home is easier

Or just sent your PCB gerber files to a fab.

[Tactile]

Remember that the copper tape is designed to be conductive on one side only - the other side is covered with adhesive. If you lay the end this strip on top of that strip you'll probably not get a connection. A dab of solder at each intersection will probably take care of that.

[smurkcity12]

I'm definitely ignorant of the ins and outs of pcbs (and electrical engineering in general) but there was a cool post on reddit (I believe it was r/mk) where a guy etched out channels around the traces he needed in order to isolate them. So the board was still mostly copper but the base material kept the current in between the etched channels in the copper. Not sure if you'd be interested in it at all, but it was a neat concept and somewhat related to what you're looking at doing.

[vvp]

... a guy etched out channels around the traces he needed in order to isolate them. So the board was still mostly copper but the base material kept the current in between the etched channels in the copper.

Or if one has access to a cnc router then the etching can be done by the router.

[Arbor]

.. a guy etched out channels around the traces he needed in order to isolate them. So the board was still mostly copper but the base material kept the current in between the etched channels in the copper.

^this. When creating a PCB you can leave in an entire copper layer for, say, GND, and etch the traces inside that leaving almost everything copper with minimal waste. Here is an example from a PCB I am working on (the darker areas are where the copper is etched out):



Also, I have heard that modern fabs can reuse most etched out copper so it is not so much of a problem as it used to be.

[ag123]

hi all, thanks for the responses, as i'm pretty much noob for the pcb techniques and that i'm thinking out ways to make a pcb for a custom keyboard, hence i'm thinking aloud
one of those things that i'm  thinking is that since we can laser cut an acrylic plate, we can also laser cut an acrylic keyboard pcb.
the trouble would be that then the wires need to be laid out manually rather than etched like conventional pcb
and given that acrylic is pretty soft, if we use 1.5mm acrylic it would likely be very wobbly.

but laser cutting the 'pcb' is a rather interesting idea, the main thing is that it can take care of all that holes which the switch and the 2 terminals sit at good precision, this can save a lot of effort / time.

other ways i'm thinking of is to get FR4 pcb boards, possibly without the copper and laying out the wires manually
but large boards aren't quite easy to find really. especially on ebay  / aliexpress

and oh yes, lets just say that i go with the 'laser cut acrylic pcb' and say it is 4mm thick (vs the conventional 1.5mm thick, how am i going to solder the pins which is at most 3mm (slightly more than 1/10") long? i go to a rather extreme thoughts about using brass eyelets, that can help extend the hole so that i'd be able to solder them even on thick acrylic sheets,
https://www.ebay.com/sch/i.html?_nkw=1.5mm+brass+eyelets&_sacat=0

[vvp]

I doubt one can laser cut copper on a pcb without cutting through the pcb. The same problem will be with copper tape on acrylic. And etching copper manually is a pain compared to the methods we proposed.