How to Make a Professional Printed Circuit Board: the Complete Guide

Hello everybody, today I will show you how to make professional PCB, to improve your electronic projects.
Let's start !

Step 1: What You Need to Buy

Exposure box

Presensitized epoxy

Tin solution (optional but recommended)

NaOH (sodium hydroxide)

FeCl3

Acetone (you can find it in a supermarket)

( Here is the link to the project related to the PCB you will see in this tutorial : Computer Control Box )

Step 2: Drawing the PCB

If you already have the design of your PCB in a file, you can skip this step

I am using Proteus software to draw my PCBs, but you can also use Fritzing software to do that. The most important is that you can export your design into a .pdf file. PDF keeps real size so if you print this file to a 1:1 scale, you will not have scale troubles after printing.

Step 3: Printing the Artwork

Now print the PCB design on transparent sheets
I advise you to print a least 3 copies of the artwork, you will get better results because the opacity will be better at the exposing step...

Step 4: Setting Up Chemicals

During these steps, wear gloves and work in a well ventilated area and wear a pair of goggles. You will handle strong bases and acids. Some of them evaporate easily in the air. I also advise you to wear a lab coat or old clothes because an iron chloride spot can not be cleaned. It lets a disgusting yellow-brown color ...

/!\ Never pour liquids containing metals into the environment /! \ Use a bottle of chemical waste that you can give to a waste disposal site.

Prepare a bath of relelator for prepositive sensibilized epoxy. It is just sodium hydroxyde ( concentration 15g/L ) Let it to the room temperature.

Prepare an other bath with a solution of iron III chloride (FeCl3)
If you want the reaction to go faster, you will need to catalyse the reaction between the acid (FeCl3) and copper of the PCB, it means you will need to heat the iron III chloride solution. To do that, I use a hot water bath (see pictures) Without this, the result will not be as expected.

Heat the water in a boiler to a temperature of about 80 ° C, once it is hot pour the water into a larger container than the FeCl3 one. Place the FeCl3 bath in the hot water bath.

Also prepare a water bath, (distilled water is better) to wash the PCB between each steps. It is also a good idea to keep absorbing paper next to you... When you wash the PCB, absorbe water on it to not dilute the next bath.

Step 5: Exposing the PCB

Let's set up the UV-light exposure box.

Take the first artwork and attach it to the pane with adhesive tape. (Be careful about the orientation of the artwork !)

Then add the second and the third design onto the first one to improve the opacity. This trick will prevent UV rays to cross black lines of the design.

Now you are ready. You will work with photosensitive resin, so you will have to work in a place where the brightness is reduced until the PCB is not developed.

Ready to start ? Go!

Carefully remove the protective film of the PCB. Place the sensitive side into the design and secure it in place with tape. Put all of this into the exposure box, sensitive side facing the UV tubes and close the box.

Turn it on between 2' to 2'30" no more. During this, put gloves and goggles to protect yourself from chemicals. Once time is over, switch off the exposure box, open it and take the PCB.

Step 6: Developing the PCB

Place it immediately into the sodium hydroxide bath, sensitive face up. You should immediately see a blue-purple color (sometimes grey) going into the sodium hydroxide. Slowly shake the bath until you great see the design. (Around 30" - 60")

Wash the PCB into the water bath.

Step 7: Engraving the PCB

At this step, the PCB is not photosensitive at all, you can switch on the light !

Now place the PCB copper-face up into the acid bath (FeCl3) and slowly shake it back and forward. The solution always need to move to the reaction take place. (About 20' to 40' depending on the water bath temperature, the surface area of copper to disolve and the concentration of the FeCl3 solution.)

When all copper have been dissolved by the acid, remove the PCB and wash it into an other water bath and dry it out.

Step 8: Washing the PCB

Now you need to remove the remaining resin on the circuit. To do that, place the PBC into an acetone bath. Acetone will become purple. (Around 10" - 20") The copper is henceforth exposed.

Then wash the PCB into water, and you are done !

Step 9: Tinning the PCB

It's an optional step but I advertise you to do it because it will help you to solder components and prevent corrosion.

Place the PCB in a empty bath and pour a little bit of tin II chloride solution on it. It will lay down tin on the circuit.

*** Success ! *** You made a professional PCB !

Step 10: Drilling the PCB

Use a vertical drill and a 0.8mm drill bit to drill every holes, and if the pin of the component is too large to go through, use a 1.2mm drill bit to enlarge the first hole. ( Always start with the smaller drill bit you have, to drill a precise hole ! It is very important ! )

And your PCB is done ! The only remaining thing is to solder your components on it !

I hope you like this tutorial

If you have any question, leave a comment ! ;)

( Here is the link to the project related to the PCB you saw in this tutorial : Computer Control Box )

Comments

[yaaman1980]

Instead of Fecl3 use HCL would be fast and cheap process

[bruhnstv]

HCl is too strong an acid for the photoresists I've used, and it's really not all that good an etch for copper. You can use cupric chloride instead of ferric chloride, which lets you see what's going on better as it's a pretty blue transparent solution. There are other good PC board etchants...easy to find with a search. If you use ferric chloride and have trouble after etching several boards with a precipitate, try adding just a little HCl; the solubility product of ferric and hydroxide is very low.

A little trick I use is to FLOAT the board on top of the ferric chloride. If you're doing a single-side board, you can kind-of see through it to monitor the etching progress, and the etch is cleaner. My "working hypothesis" is that the copper-laden solution is heavier than before the etch happens, so it "falls away" when the board is floating upside down. I can do 0.13mm (5 mil) lines and spaces this way when I need to.

If only there was a good way to do plated holes!

[RubenP51]

For the last 31 years I've used a mix of hydrohloric acid 30% strength, hydrogen peroxide 30% strength and diluted it with 1-2 parts of water. Use a small container, bathe the board about 3cm deep. (for example 50ml hcl, 50ml h2o2 and 100ml water) change ratio when you use stronger or weaker stuff. (if you use 10% strength don't dilute, 3% doesn't workt) The mix etches the board with perfect results in about 1-5 minutes. Do it outside, it fumes unhealthy stuff. Strong peroxide is very bad for skin and clothes. When done, neutralize the acid with plenty of soda till it stops fizzing and flush thru the toilet. The only thing going down the drain is soda, salt, a bit of peroxide that will very quickly turn into oxygen and water and a gram or so of copper hydroxide (basically rusted copper) which isn't dangerous to plumbing or much of an environmental threat.

[Polymorph]

Why would you throw that away? HCL and H2O2 after etching become CuCl, which is a great etchant. All you have to do to renew it is either bubble some air through it, or add a little H2O2.

[syevtushenko]

Well, almost any acid is not a problem for photoresists. I've experimented with several etchants and found that HCl + hidrogen peroxide is the best. Main advantage of this solution is a high uniformity of etching. FeCl3 is close, but is slow, requires heating and eventually stops etching because of too much copper in the solution. T

[Joebarteam]

Thank you, I will try :)

[MikeV120]

but sorry, don't forget to say , it's very gifty and will climb up your walls of the room , it stinks as acid and burns your skin and the eyes .You need to clean the room by chemical cleaners , take of the wallpaper and keep it new. DANGEROUS !!!

[Joebarteam]

Step 4 : " During these steps, wear gloves and work in a well ventilated area and
wear a pair of goggles. You will handle strong bases and acids. Some of
them evaporate easily in the air. I also advise you to wear a lab coat
or old clothes because an iron chloride spot can not be cleaned. "

Before you post a derogatory comment, please read the ENTIRE Instructable :)

[JetMechanic]

Great Instructable, especially for beginners like me.

I did encounter some confusion however, looking for 'Presensibilized' epoxy boards, as per the link in Step 1. After some trouble, I do now realize what was meant was 'Presensitized' epoxy boards.

Maybe a correction there will prevent trouble for other Newbies like myself in the future, who are just learning the difference between a PC board and a snowboard.

[Joebarteam]

Thanks a lot, I will change this right now ;-)

[preschau]

I found that sodium metasilicate (brewers detergent) works well as a developer, it's not as dangerous or corrosive as the caustic soda mentioned above.

I use about 50gms to a litre of water and this will develop a board in a couple of minutes.

To remove the photoresist after etching, methylated spirit (denatured alcohol) works well and is cheaper and easier to obtain than acetone.

[ram713]

Good refresher as I did this 20 yrs ago. Many refs use symbols that represent feet and inches ( ' and ") and don't make much sense.... the reaction take place. (About 20' to 40' depending on the water bath temperature, .... Acetone will become purple. (Around 10" - 20")

[polonius]

I think you are getting symbols confused. In this context these symbols are used for measuring time, ' being minutes (About 20 to 40 minutes...) and '' seconds (Around 10 to 20 seconds).

[eqwipman]

Thanks I needed that. I was confused.

[Orngrimm]

If downloaded as PDF, the step 1 is incomplete...

[Kolynskij]

I made these boards for quite a few years. The example you show is under-exposed, give it a few seconds longer in the UV box. Make sure your glass is clean. Longer UV will crisp up the edges, and define the gaps.

Under-exposing usually means you over-etch to compensate, and you lose definition.

[AngeloBrito]

Very interesting process, it is similar to the Photo Paper + Laser Printer + Clothes Iron + FeCl3. This one, which I had to use on university, is cheaper but the finishing is horrible. Though, if you have access to a maker space you can also use a laser cutter machine to engrave on a black painted copper board and corrode the copper.

Which one to do you think would have a better cost vs finishing?

And nice work!

[Claudiohase]

You can use magazine paper, is better than photo paper ! It is lightly waxed paper, and laser printer ink takes off more easily. I have used for a long time !

[AngeloBrito]

I liked this feedback. I will try this out. Thanks!

[Joebarteam]

If you have access to a Maker Space with the appropriate equipment (CNC machines...) it must be cheaper and the result may be better than the method I described here. But if like me you love making everything by yourself, this method is a very good one. ;)

Thank you