Saturday, 30 March 2013

Steampunk Electronics–Heartbeat Part 4

The Home Made PCB

Today I made my first home made printed circuit board. The challenge was to design the and etch a circuit board.
I decided to use the Hydrochloric acid and Hydrogen Peroxide etchant.
I had previously designed the circuit using Fritzing and then printed it out on plain 80gsm copy paper. I had heard that this wasn’t ideal, but what the hell … we are just prototyping, so whatever.
I used the iron on Linen (the hottest setting for our iron) and pressed the design onto the copper clad board. Next, I bathed the copper clad board in water to get the paper off.
Things looked pretty OK at this stage, the print transfer was not too bad, I could see some pitting under the magnifying glass. But … let’s see how it goes. I decided to use my Sharpie pen to improve the lines somewhat.
I made the etchant from 1 part Hydrochloric acid mixed with 2 parts Hydrogen Peroxide. I bought a 200ml bottle of 3% Hydrogen Peroxide from the chemists and a 500ml bottle of Hydrochloric acid from the hardware store. I also bought some Isopropyl alcohol and some nail polish remover so that I could clean the board once it had been bathed.
Before doing anything, I got some glasses on and put on my heavy duty rubber gloves. I also prepared my work surface, putting down a 1m x 80cm plastic mat to protect the table.
I poured the 200ml of peroxide into a clean and empty orange juice bottle and then measured out 100ml of acid and poured it into the bottle and gently agitated it.
Next, I poured a small amount (about 100ml) of the solution into a smaller plastic container and then I put the copper clad board into the solution … then I waited.
About 10 minutes later, I had a nice looking board with all of the copper dissolved away, leaving the black laser toner and Sharpie ink.
I took a tissue and rubbed the toner and ink off the board and then gave it the once over with the rubbing alcohol to be sure.
The result was quite reasonable … it still looked a little pitted in places, but testing the board with my multimeter showed that the traces were not broken. I used the multimeter in continuity mode.
Then, I got out the components to solder to the board, the soldering iron and the solder and fixed the components onto the board.
Sorry about the poor quality of the pictures.
Then I powered it up and got … nothing.
The step that I missed, the step that I should not have missed, the thing that I failed to do in my impatience to go from design to circuit board was … relaying out the prototype board with the changed design. Now I need to go back to the drawing board and do it all over. Still, that’s not that much of a problem, it is fun and it’s a learning experience.

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