Wednesday, 6 January 2010

Home-made (bodged) PCBs!

For a little while now, I've been interested in trying to make my own PCBs using the laserprinter method discussed on MAKE. I finally got around to trying the method today, and I'm really impressed with the results! For my first attempt, it worked well.

I needed a temperature controlled waterbath for a separate project, and I found a suitable circuit on the internet, courtesy of a Make article.
Instructions and comments below:

It had a PCB diagram, so I didn't need to mess about with designing my own.
Print out the PCB diagram, at the correct size, mirrored, then use it to cut a copper PCB to the right size. For my first attempt, I made a couple.Make it as dark (as much toner) as you can.
From PCB
Clean the surface of the copper as well as you can. Any grease stops the toner sticking. I used a green scourer and some 'Cif'.
From PCB
Take your dark laserprinted PCBs, and tape the copper side of the PCBs to the stencil.
From PCB
I then ironed the back of paper (setting on 3 dots), letting the heat soak into the copper. The heat causes the toner to melt and to stick to the copper. Spraying water on the back of the paper, you can see the toner stuck to the copper:
From PCB
Using water and rubbing, most of the paper can be removed, leaving the toner on the PCB. It seemed to be pretty well stuck on, and only a couple of little gaps.
From PCB
When you've got the paper off you can see the layout on the copper board. Any gaps or tidying up can be done with a sharpie marker - apparently they are also etch-resistant, like the toner.
From PCB

Now, it's time for the etching. I got a standard bottle of etching solution from Maplins. Note that this can be messy and this stuff is nasty chemicals - treat with care. It will stain pretty much anything it comes into contact with (including stainless steel sinks!). Wear rubber gloves and take care.
I poured some into an old plastic container, and used a soaked tissue to dab and rub it onto the board. The toner works pretty well as a stencil, resisting the etching - and dabbing it by hand allows you to pay extra attention to the edges or places where it needs more.
No pictures, I'm afraid, as my hands were all dirty.
After a few minutes, it's fairly obvious when the copper is etched away. I was able to rub over a few areas that weren't quite done yet to finish it off, then I dunked them in a big bucket of water to clean them up.
The black toner can then be scrubbed off using a green scourer, leaving a completed board:
From PCB
This left a pretty good result. It still needs drilling (a chance to use my new Dremmel! Yay!) and a little repair where the toner didn't stick, but I'm pleased with the first attempt.

This technique looks suitable for the few 'one-off' boards for specific projects now and again.

The final result:
From PCB


Pat Galea said...

I wish I'd had that when I was a kid!

Renoir said...

Erm... a laserprinter? or a bottle of etching fluid?

Pat Galea said...

Ah, that was a bit ambiguous! :-)

I meant a printer. Back in the old days, I had to draw my PCBs using a special pen. Took bloody ages!

BodgeIt said...

hey looks like you are uffering exactly the same problems I had doing this. top of left board over etched track missing. bottom left of both boards under etched three pads ajoined will need cutting with a scalpel.

From your pictures you had a similar problem in removing the paper after transfer. There is a blog / page some place on line sugesting a specific paper that just peels away cleanly from the board another sugests using the backing of sticky lables. I have not tried either yet as I was very disapointed with the results of doing exactly what you have just tried. I did build 1 of the boards but felt it was a waste of time fixing every pin hole crack in every track. at that point I bought the boards from Zack yep a long time ago now.
The chemicals are still in Midges utility room ready to try again.

Maybe I should take pics of the stripped down board pop it up on the blog its still amongst my RepRap bits. I still have the un etched boards as well.

Joe said... for the toner paper. Soak it in water for 2 minutes and the paper will fall off.

i got it for christmas and using the included designs from the kit i was able to make 6mil traces in one shot.

Christian said...

Cool process,
I remember in my young days, I used to do some PCBs using laser printer.
In my case I printed on standart paper the drawing being mirrored, then I oiled the paper (even used cooking oil).
This way it was a bit transparent, then i put paper on PCB board, ink side stuck to copper surface (hence mirrored printing).
I insulated at lower power (UV lamp moved up) for a longer time and then etched.

I also got good results with printing on transparent paper, though it's risky as some transparent paper may melt during printing and damage printer.
Key thing is to have the ink stuck to copper for insulation, so UV rays cannot hit copper under ink.
Insulating with ink on top of paper gave lots of micro cuts.

Good work!


Renoir said...

Thanks for all the tips!

Christian said...

looking at Pat's comments, did you try to use your RepRap to draw directly on PCB using a special EtchResist Marker pen ?

Also, may be there is some type of plastic that can stick to copper and is resitant to etching.

I wish I had one RepRap to try :).


Renoir said...

I haven't tried drawing with the RepRap yet.

BodgeIt said...

Hey I just tried this using the backing of sticky lables as the transfer medium & It works great !!!