PCB production/etching tutorial

Introduction

There are a lot of tutorials around that show you, how to etch your own PCBs, but either they use professional tools, that might cost a lot, or they do not give you a complete list of materials you will need. This really bothers me, so I want to show you how to produce your own PCBs at home, so you can make your DIY projects more professional and cut costs drastically when it comes to create a PCB.

electrician-499799_1920
This might be you with your professionally crafted PCB

For many years I’ve ordered my PCBs from a german company, that always made a great job. Before I found this company, I made PCBs myself. The results were good, but when it came to very fine details or a solder mask was needed, it became harder and harder to make such special PCBs at home without professional tools. You can make PCBs for less than 2€ each, which is way cheaper than ordering them. Obviously the cost of a PCB will increase in it’s size and features.

Disclaimer

Don’t do this if you are not 100% sure with what you’re doing. You can seriously injur yourself and others if you make mistakes. Also you can’t blame me if you do something wrong and you cause damage to yourself, someone else or any objects around you. This site assumes that you’re skilled and mature enough to handle chemicals. Use appropriate safety gear. Also make sure you inform yourself how to dispose the used chemicals correclty. See the last section of this article for more informations.

List of materials

I’ve come up with the following list, please consider that you’ll also need protective (acid resistant) gloves and goggles, but I had these around anyways.

I bought everything at conrad. If this shop is not available in your region, you can find all the items on amazon, where they might even be cheaper.

Price Product Link
7,99€ Iron (III) chloride, 1L Link
11,99€ (Optional, but recommended) Anti corrosion spray paint Link
4,09€ Sodium hydroxide, 250g Link
1,69€ Photopositive PCB base material, 35µm layer thickness, buy whatever size/thickness you need. Link
11,99€ Laser overhead projector printable foil Link

List of additional materials. I recommend these, but you can basically use every acid safe plastic tray, tweezers and safety gear you want.

Price Product Link
12,99€ (optional, you can use any strong light source like the sun or a strong lamp) UV lamp Link
4,99€ (buy at least 2) Plastic tray Link
3,49€ Plastic tweezers Link
8,80€ Gloves Link
4,70€ Glasses Link
Optional An (old) picture frame

All prices were up-to-date by the time, this article was written. I can’t guarantee that these products will be available at this price by the time you read this article.

Preparing your PCB-design

Okay let’s start with a PCB design. I usually create mine with Eagle, which is available in a free version for Windows, MacOs and Linux. However, I’m using the Pro version, but it shouldn’t make any difference. I will use this sample circuit board for testing the etching process:

pcb-1
Figure 1: The complete example-design

This design was not made by me. It’s a sample project which comes with eagle. If you have to have a double-sided design and you don’t want to create a double sided PCB, you can try to design the bottom side as simple as possible, so you can connect the vias with hard wire manually after the etching process. Like I did in this design:

pcb-bottom-example
Figure 2: The bottom layer (blue) was design as simple as possible. Basically just straight lines that can easily be placed and soldered manually.

Now let’s get back to our sample design. First you’ll have to turn all the layers off, which you don’t want to be printed. Remember: Everything you print on the foil will not be etched away in the process afterwards. So you basically want to keep all the pads, vias and (top/bottom)traces, but only one of them, not both at once! So I’ll turn everything off except for the vias, pads, the top and the dimension layer:

layers
Figure 3: Turn all irrelevant layers off.

Afterwards your design should look like this:

pcb-2
Figure 4: Only the top, via, pads and dimension layers are displayed

Now you are ready to print your design. Make sure you print it at a 1:1 ratio, so that it has the right size and use the black and white settings of your printer. Not grayscale, pure black and white. I came up with the following settings. I translated the relevant settings and labels:

pcb-3
Figure 5: Printer settings

The resulting pdf-file should look something like this:

pcb-4
Figure 6: The top-side of the design, ready to print

Now review your design once more and then print it on max settings. Of course you can print the design right away, it’s not necessary to create a pdf and then print that one, but I like to review the design one last time before I print it.

If you have a double-sided PCB design you can either change the design, so it’s single sided (or the bottom-layer can be done by hand, see fig. 2) or you can buy double-sided PCB material and repeat the steps above for the bottom side as well, so you end up with something like this for the bottom-layer:

pcb-6
Figure 7: Bottom side of the design

Even if this is possible, it makes the whole process much more complicated to do, because you’ll have to expose both sides of the board to the same amount of light and do this evenly on the whole surface. It’s not impossible though.

You’ll have to print both sides seperately and then align them properly, so that all the holes and pads are aligned. That’s why I like to print the outline as well. It makes aligning the both sides so much easier.

Preparations for etching

Lay everything out nicely on an acid resistant surface (don’t do this on marble or metal for examble). Put the two trays side by side and get yourself a plastic spoon for stirring. Read the informations on the packaging of your etching and developing products and get your safety gear ready. It’s also not a bad idea to have a tap nearby if you get some of the chemicals on your skin. But don’t pour any chemicals into the trays yet.

layout
Figure 8: Lay out all your trays and tools

If you haven’t done so already, print your design on a sheet of printable foil:

foil
Figure 9: The design printed on a foil

Afterwards cut your PCB material and the foil with your design to the right size. If you’re using a picture frame, tape the foil on the glass (watch out not to cover any traces of your design with the tape) and make sure you flip it the right way round, otherwise you might end up with a mirrored design:

frame
Figure 10: The foil with the design printed in the frame

Taping down the foil down isn’t necessary, however it makes aligning the PCB material much easier, because the foil won’t slip away.

Now make sure you are in a completely dark room. Turn off all the lights. If you can’t do this step in complete darkness, you can get yourself a very dim red LED. Now pull off the protective film of your PCB material (in my case it’s blue, after pulling it off you should see a blank copper surface which you must not expose to light during alignment) and align it, so that the printed design fits it perfectly:

frame2
Figure 11: The PCB material aligned with the layout

Afterwards you’ll have to expose the whole thing to light. So use what ever source of light you’ve chosen. With my UV lamp it takes about 10 minutes of exposure. You might need to experiment with the timing according to your light source and material. If you’re using an UV lamp, make sure you don’t put your skin under the lamp for too long. Also don’t look directly into it. However I think this is self explanatory, I mean you wouldn’t look into the sun directly for too long eather, would you? 😉

After you have exposed it to the light for enough time, bring the PCB (without the foil and frame) to a dark place again and store it there until needed. Try not to expose it to light too much during storage and transportation. Now we’ll deal with the chemicals.

The etching process

Put on your safety gear now!

First we’ll have to develop the material, so use your developer according to what the packaging says. Mine says to dissolve 10 grams of the NaOH in 1 liter of 20°C warm water. Afterwards store the solution in an air-tight container until needed. So just dissolve it and put the PCBs into the solution. If you’ve exposed it to the light correctly, you should see an effect quite soon after putting it into the NaOH solution.

Leave it in there, until the areas, which were exposed to the light earlier, get shiny and metallic, which should take about 3 to 5 minutes. Your design should be visible like a shadow on the material. Stir the solution continously throughout the process. Take the PCB out of the solution and rinse it with water. It should look like this:

developed
Figure 12: The PCB after the NaOH treatment

The NaOH solution is only suitable for one application, you’ll have to dispose it after the process (see the end of this article).

After washing the PCB, pour enough of the Iron III chloride into the other tray. Now put the PCB into the acid. Leave the PCB in there until all the shiny copper, which was exposed to the light earlier in the process, is gone. Depending on how often you’ve already used the acid, this should take about 20 minutes. Stir the acid every once in a while and look at the PCB. During the process it should look like this:

acid
Figure 13: The acid slowly dissolves the copper that was exposed to the light earlier

Don’t leave it in there for too long, otherwise the acid might dissolve copper where it shouldnt.

If the acid is warm, the etching process is quicker. You can warm the acid in the tray by putting the tray in a larger one filled with hot water (like I did) or by using an (old) aquarium heater. Just make sure the temperature of the acid stays between 20° and 60° celsius.

Take the PCB out of the acid and rinse it with water. The acid can be reused as long as it is still strong enough to dissolve copper. Just store it accordingly or dispose it correctly after the process.

Last steps

Now you’ll just have to drill the holes for through-hole parts and you’ll end up with your finished PCB. Afterwards you can treat the finished PCB with further finishing products if you want to. I usually spray mine with a coat of anti corrosion spray which can be soldered on. Refer to the packaging of the product you want to use for instructions!

Unfortunately I messed up the process because I didn’t expose the material to the light long enough so I don’t have a picture of the finished one. I’ll retry the whole process tomorrow with modified timings and I’ll post the results as soon as I’m satisfied with the outcome.

I tried it again and this time it worked without any major problems. However in the top right corner you can see a little white spot, that was not etched away properly, so I decided to scratch the copper that remained there away with a knife. Also my printer somehow cut off 1mm of the right edge, that’s why the most right pad on the top is cut off. However that is absolutely no problem. It’s just a cosmetic issue.

Overall I’m satisfied with the outcome. Here are the timings I used:

12 minutes exposure to the UV-lamp
5 minutes development time
15 minutes of etching. However I let it sit in the acid for 30 minutes, but this little piece where the white spot is, just didn’t want to etch away. But basically it was done after 15 minutes. The acid temperature was 55° Celsius.

pcb-finished
Figure 14: The finished PCB

Disposal of the chemicals

Don’t forget to dispose the chemicals correctly! Simply pouring them (especially the acid) into the sink is illegal in most countries and the copper that remains in the acid, is very bad for humans and basically every organism that lives in water. Not to mention how bad it is for the environment. Even if pipe cleaner is usually just NaOH, I wouldn’t just pour it into the sink either. You’ll have to bring the used chemicals to your local waste collection site or recycling plant (which should be free in most cities). You’ll have to look that up online according to the place you live. If you live in Vienna, I can give you this link which contains general informations about disposing chemicals and this one, which shows you which waste collection sites accept chemicals.

Conclusion

You can produce PCBs at home, it’s not too hard. But you’ll have to experiment with the materials you have and you’ll have to accept that the first PCBs you’ll make might not be usable at all. Just keep trying and documenting your mistakes.

If you are not completely inexperienced with webservers, databases and such, you can use this tool I quickly put together for myself, if you don’t mind that it’s not state of the art and just quickly put together.

Do you have any experience with creating PCBs at home? If not: what projects do you want to create a PCB for?

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3 thoughts on “PCB production/etching tutorial

  1. I never made pcbs at home before but definitively going to try it! Hopefully they turn out well. I need them for a project of mine where I basically want to create a small motor controller circuit with some mosfets.

    Liked by 2 people

    1. I’m sure you’ll manage to craft good PCBs! Just don’t give up when they don’t turn out perfect. Mine didn’t turn out very well eather. It heavily depends on the materials you use. You’ll have to experiment and document your failures to master this skill.

      Liked by 1 person

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