Making Circuit Boards, Second Attempt

I took another crack at making my own circuit boards, and with much better results. The first thing I did was change the design to be better suited for toner transfer. The traces before were 0.010″ wide, so I bumped them up to 0.016″. Doing that makes the breaking of traces less likely when transferring the toner. I also put more copper around the pads for the five jumpers,  so the copper I accidentally remove during drilling doesn’t make too much of a difference.

So, to start the process, I printed the design onto some magazine paper. I’ve read that some other papers work well, but magazine paper is pretty much free (this is a page out of a Jameco catalog they sent me), and it works pretty well.

Next up, I cut the blank circuit board and cleaned it up with some 600 grain sandpaper.

While ironing the design onto the board, I found that it’s rather easy to over-iron the plastic toner from the ink. The first time around, I cooked the plastic, so it was bubbly and ran everywhere. It only takes about 45 seconds on mediumish temperature to get the toner to transfer well. To make sure that the paper didn’t slide around while I ironed, I left a lot of excess paper around the design to tape to the table over the circuit board.

After ironing and soaking the paper to get it to peel off, I found that I actually got a great transfer on these boards. You’ll see that some of the ink that was on the page originally also transferred, which turned out to only be significant for one board. However, this happened in an area that didn’t affect the circuit, so I just scraped the copper off with a razor blade after etching the boards.

To etch the boards, I opted to not use the more common ferric chloride etchant in favor of something that’s a little easier to get a hold of and dispose of. It’s a 2:1 mixture of hydrogen peroxide from the drug store and muriatic acid, also known as hydrochloric acid. To get the boards to etch in a reasonable amount of time, the solution needs to be agitated. It only took about 10 minutes for these boards to finish. The picture on the left is when they were closer to done, with most of the copper gone. I started them face down in order to give all of the copper on the bottom side of the board enough time to dissolve, as well.

Before removing the toner, I drilled out the holes for the through-hole components on this board. I drilled before exposing the copper because the black toner is more visible against the bare circuit board, which makes drilling easier. I used my Dremel drill press with a 1/32″ bit for the smaller holes, and a 1/16″ bit for the larger ones.

Finally, all I had to do was take the toner off with some nail polish remover to expose the traces.

Soldering the capacitors was easy enough, as they’re just through-hole components. The MAX1555, a surface-mount component, was a little more difficult, but I had a little bit of experience with them. First, I got some solder on the top two pads. Then I positioned the IC over the pads, held it down, and melted the solder beneath the pads to secure the component in place. The last three pins were just a matter of heating while getting some solder melting.

Soldering the jumpers on was interesting, because the holes were too big. Getting the board and the jumpers to be at a right angle took a little bit of luck and experimentation, but the boards were done!

The last step was to number and date them. I tested these boards out on a breadboard with a Li-Poly battery from SparkFun, and it worked! Unfortunately, I can’t go into details with it because it’s for a project that’s a present. I’ll be making a post about that present after it’s been given.

 

Oh, and, uh, I learned all about the importance of using a good soldering iron and solder. I tried populating the board in the last post, without much luck. The iron I was using was too cold, and the solder was abysmal; it didn’t flow at all. This was the sad result of using my secondary tools.

Ben Oztalay

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