How-to: Make your own PCB (not vero)

[Twisted]

Hey, new to this forum, and I noticed most of the pedal stuff is vero or standard pre-made, ordered circuit board. Of the mentions of etching, they all refer to using the nasty ferric chloride etching solution. I just wanted to share how I make my boards and how easy and cheap they are to make.

First step: design (or steal -er, acquire) the layout.

I played with Eagle, but for what I'm doing it was over-kill. Instead I use a program called ExpressPCB (and its companion ExpressSCH for schematics). Its a much smaller learning curve than Eagle, and I had my first design in just a couple of hours. It allows you to design in three layers - bottom, top and silkscreen. The main problem with this program is that it does not offer an option to reverse the top layer and silkscreen for proper transfer. More on that in a bit. So, anyway, its good for single sided board design, which for pedals is pretty much all you need. The ExpressPCB program is small, free and does allow you to create custom components in addition to the stock ones. In reality, for the designing of the PCB, you only need basic components (you don't need to specify which op-amp you are using, just that it is a 8-pin DIP). I use maybe 10 generic components (resistor, 3 capacitor types, 8-pin DIP, 3-pin tranny, off-board wire pad, etc). This will be the longest, hardest part of the process.

Don't forget to add screw holes if you are going to mount it that way. Also, when using ExpressPCB, be sure and design and print the bottom layer, so that it is reversed like you need.

Step two: print the layout using a laser printer.

Don't use the ink jet photo paper. Find an old color magazine with thin glossy paper. Remove the staples and cut the pages as close to letter size as possible with no rough edges. This paper has the print with ink inside the paper beneath the gloss. When you print onto it, the toner melts onto the top of the gloss and can transfer easily. Be careful when you print, as the thin paper can easily get jammed in the printer (hence the no rough edges). Be sure and use the manual feed, and feed it carefully. If you have any toner saving setting (eco print, etc), turn it off if you can. You want as much toner used as possible.

Step three: transfer the design to the board.

Get your handy-dandy clothes iron and set it on hot. On mine, I set it to the first steam setting (without any water in it), which is third from highest setting. I imagine a little playing with is required here to find the best setting.

Cut the magazine paper with the layout on it so that it is very close to the edge of the layout on two linked edges. In other words cut it so the layout is in the corner of the paper, but leave the rest of the paper there so you can more easily adjust where the layout is on the board. Put the layout in the corner of your board as close to the edge of the board as possible, face down. You may want to use a piece of tape to hold the layout in place, but don't put the tape on or very near the layout. Then lay 4, 5 or 10 sheets of paper (or I like newspaper) over the top of everything.

Use the iron to melt the toner in the layout onto the board. I just iron the whole thing, like I would a shirt. Move the iron around and put a bit of pressure on it. Iron it for a couple of minutes. You will know its done when you pull gently on the magazine paper and see that it is stuck to the board. Be careful and make sure the whole layout is stuck to the board, not just part of it. Be careful also because the whole board will be hot, possibly enough to burn you.

Step four: remove the paper.

Put the whole thing in soapy water and let it soak for a while. Gently, slowly, using your finger, rub the soggy paper away. I've found that sometimes it will peel away from the melted toner, but resist this urge because more often than not it peels some of the toner up with it. Just rub the paper away. I use medium speed wipes in the same direction with my thumb, and the paper pulp will roll up and collect at the end of the wipe space, which I get rid of with a quick swish in the soapy water. This is the trickiest part of the process.

If it looks like the paper is coming off well (all over) and the toner is sticking (all over), you can use a wet Brillo pad (green dish washing scrubbing pad) with gentle pressure to remove the rest of the paper or any stubborn areas. Usually, some of the paper will just not come the toner, making it look dusty (not pure black like the original printing). That is OK. The main thing is you want the uncovered copper to be, well, uncovered. If there are any small areas where the toner comes off, you can use a fine-tipped Sharpie to tidy it up. The permanent ink from the Sharpie will protect the copper from the etching solution, but not nearly as well as the toner does. I've found that I have to re-do the Sharpie touch-ups a few times during the etching because it will slowly come off. It may just be me, but it seemed blue Sharpies did better than black (?).

If it does not work out and something is wrong with the transfer, just use the Brillo pad with FIRM pressure to scrub the toner off and do it again. You may even want to do this a few times just to practice before tackling an actual project, so that you know how hot/how much pressure/how long to soak/etc/etc/etc.

Step five: cut out your circuit.

I use a Dremel tool and a cut-off wheel to cut as close to the edges as I dare to separate the circuit from the un-used portion of the board. If using something else, be careful and check if you are snagging/shredding the copper edge where you are cutting. That could screw everything up if it peels the copper away from the board.

Step six: etch it.

The etching solution I use is half distilled white vinegar (5% or 9% acidity) and half hydrogen peroxide. It is clear and smells like salad. It is better that ferric chloride (the standard etchant solution) because it does not stain, is clear so you can see the progress, smells better, is much cheaper, and doesn't give you the willies about spilling it or touching it. It may not be quite as fast, but I'm not sure. It works great for me. You don't need a super lot of the solution. For a typical pedal circuit, I use a plastic container (from the kitchen) about 6 inches by 6 inches, and about 3 inches deep with a flat bottom. I fill it about half way up.

Drop your circuit into the solution. Watch it for a little bit and see if it starts fizzing where the copper is exposed. This is a somewhat slow process (15 minutes+) so don't worry about it burning through all of a sudden. Sprinkle some salt around and on top of your circuit. The fizzing should increase. I use the pure salt without the added iodine, just because I don't know if the iodine will interfere with the chemical processes going on. I read some articles about this solution and the addition of the salt, and the salt helps carry away some of the ions that are produced and "refresh" the solution. In other words, the salt makes it work better. I know it makes it fizz more. If you are impatient or the fizzing stops, just add more salt. I go through quite a bit of salt, a sprinkle at a time.

Stirring the solution also helps a lot. I've read about someone who made an etching container with a stirring mechanism built in that cut his etching time considerably. I've also read of adding bubbles from an aquarium air pump to agitate the mixture. I may try that one. Did I mention adding salt? Also moving the circuit around to different parts of the solution helps. Also, if an area turns blue, I take that as a build up of diffused copper, which may prevent the solution from getting to the remaining copper below it. I sometimes, if it is a large enough area, take the circuit out and carefully wipe the blue off to expose the copper. Or maybe just dab/wipe with a paper towel to remove it. Be careful if it is on or around any Sharpie touch-ups, and it may remove the permanent ink and require an additional touch-up.

Check the circuit now and then until you can't see any more copper. Then let it sit for another few minutes. Also, check any Sharpie touch-ups to see if they need re-touching. If the Sharpie areas fizz a lot, you probably want to recoat them.

The solution will turn blue. A pretty blue that makes me think of certain top shelf tequilas. If the solution gets very blue and becomes saturated, you may need to pour it out and make some new solution. Also, the solution doesn't keep for very long I don't think. Not positive on that one. Also, disposal... I just pour it down the sink. But I live in the country, and have plastic drains and a septic tank. I'm not sure what effect it would have on metal drains... It does clean metal very well (tested it on keys and such. Tested on silver to bad effect. Don't do it)

Step seven: remove the toner.

Once its done etching, take the circuit out and rinse it off in the sink. Then, under running water, wipe with firm pressure using a Brillo pad to remove the toner and expose the copper traces. You can use pretty strong pressure and the traces will not be damaged. They may get a "sanded" look from the scraping, but that is OK. Once all the black is off and it is Purty Shiney, dip it briefly back in the etching solution to clean it up and make it even shinier.

Step eight: drill the holes.

I use a drill press and a 1/16 bit (the standard is 1/32, but I don't have that size available and make all my layouts based on 1/16 so that when I drill I don't take the copper pad out completely) to drill the holes. If you get layouts from the internet, be aware they will probably require the 1/32 drill bit size. If you use 1/16 on these, the hole will be the size of the entire copper pad around the hole that the solder is supposed to stick to. It can still work, but the component lead will have to be soldered to the trace, which is a bit trickier and messier looking.

In the past I have used a Dremel tool and the engraving bit to make the holes. Takes longer but works.

Step nine: realize you forgot something and scrap the whole thing.

Er, I mean solder the components to the board and be done with it.

Also, some notes on this:
If you can create a reverse image, you can print/transfer toner to the finish board to act like a silk screen and show the placement of components, logos, model numbers, etc.
You can also etch information, so that it is in copper.
I have gotten some very fine detail into the copper using this method, including very sharp corners, text and very thin traces.
When designing your layout, be sure and have your ground plane take up ALL available space. This helps keep the circuit quieter, makes the etching process faster, and uses less etching solution.

I have no pictures available, so I will try to add pictures for each step and of finished examples. I will also try to add more notes as I think of them.

I hope this helps someone, and I'll be happy to answer any questions.

[culturejam]

You could also use DIYLayoutCreater to make your layouts. It's free, easy to learn, and is designed specifically for the pedal building hobby.

[Gone Fission]

You could also use DIYLayoutCreater to make your layouts. It's free, easy to learn, and is designed specifically for the pedal building hobby.

Cool tip! Previously unaware of that tool. Perf, Vero, and PCB all there. https://code.google.com/p/diy-layout-creator/

[Twisted]

Cool, had not heard of that one. It looks pretty cool and I'll have to check it out today (while getting paid to do something else, lol). The features list says it will export to image, PDF or printer. That right there (even if it doesn't handle reverse printing) makes it a bit more usable than ExpressPCB, because I can save the image, reverse it and then print it if needed.