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DIY PCB fabrication: MADE EASY!

posted Apr 26, 2012, 7:31 PM by Bryan Cera   [ updated Apr 26, 2012, 11:17 PM ]
DIY PCB fabrication: MADE EASY!

I finished designing the cirtcuit for the Weather Patterns project.  I havent had the chance to teach myself eagle, so I've been drawing the circuit board layouts in Illustrator.  Using a breadboard graphic as a rough guide, I drew the contacts and leads right on top of it.

I have been working on some cheap and easy methods for fabbing circuit boards.  In the past, I have borrowed Frankie Flood's desktop cnc to mill PCBs, and I've used my vinyl plotter to cut vinyl masks to use as resists for etching PCBs. Both of these were too time consuming and too messy!  So after a bit of experimentation I've come up with a quick and easy way to fab these:

I buy my blank circuit board from Radioshack, but probably way cheaper to buy online from digikey or on amazon.

With double-sided tape I stick the bare pcb onto a thin piece of plexi or polycarbonate plastic, and feed into my vinyl plotter. (The cheapo vinyl plotter I use can be bought here for ~$250.  WORTH IT.)

Instead of using the knife or pen tool the plotter came with, I stick a sharpie paint marker in the chuck.  Make sure it is the oil-based paint marker, as the water based will not hold up to the acid bath.  I use extra fine point black.

The software that came with my plotter can read illustrator files.  I load it in, zero the marker on the lower right hand corner of the blank pcb, and send the job to the plotter!  Make sure to check the "fill plot" option so the marker fills the little circles in (these will be the solder contacts).

After the print job completes, I check the board over to make sure there arent any spots where ink is missing, and also no spots where leads and traces are touching where they shouldnt be.  If I find one of these errors, I either fill in (by hand) with the paint marker, or use an exacto knife to scrape away unwanted paint.  This one looks good, so it's time to etch!

I etch with Ferric Acid.  It isn't the fastest etch, but it is not as dangerous as other acids and it is safe to flush this stuff down the toilet when you're done with it.  It takes around 30 minutes to an hour to etch a 5x7" board.

You want the resist on the board to face down, so that the copper falls down, away from the board as the acid eats it.  This means the board needs to FLOAT in the acid.  I use adhesive-backed craft foam (you can get at any art/craft store) to add buoyancy to the board.

The container I etch in is a porcelain cooking dish that has a Tupperware lid (grabbed it at Goodwill).  It is important that the container you use for etching is resistant to the acid you use.

An agitator can help speed up the etch.  This keeps the liquid moving around so that the copper plating of the board is constantly exposed to "fresh" acid.  I threw my agitator together in about 15 minutes out of an arduino, a servo, and some wood scraps I had laying around.

The board is done etching when it looks like this.  All the copper should be gone, leaving only the painted circuit layout.

I remove the paint with Acetone or Nail Polish Remover, revealing the protected copper traces.  My favorite part of the process!

Then I use my bandsaw to cut the boards out and a belt sander to fine tune their shape.  Before I had power tools, I cut these out using a Jeweler's saw and sanded them down by hand... so that is an option, too!

And now I am ready to drill holes and solder my components!  Woot!