Preparation of a solution for etching printed circuit boards. How to make your own printed circuit board at home

How to etch a printed circuit board.

For those who are just starting to engage in amateur radio design, or simply do not know how to make a printed circuit board, in this article we will present several options for etching using chemical reagents.

We would like to note right away that most radio amateurs use ferric chloride for etching boards; we will consider this option, as well as several alternatives, but we will not dwell on etching using hydrochloric and nitric acids, and many other unsafe or confusing methods. Let's consider only those options that can actually be applied at home, and quickly. So, let's take it in order.

Board etching option 1.
Ferric chloride.

Usually on the packaging the manufacturer writes in what ratio the ferric chloride solution is prepared. As a rule, this is 1: 3 (one to three), that is, 30...40 grams of ferric chloride crystals are dissolved in 100 grams of water. The etching time of the board depends on the concentration of the solution, as well as on the temperature of the solution; in a heated solution (up to 60 degrees) etching proceeds much faster. It is necessary to etch in a plastic or glass bath, and it is better to use a plastic spoon to prepare the solution.

On the Internet, we came across information on how to prepare a ferric chloride solution yourself. To do this, 15 grams of small iron filings are poured into 250 ml of 10% hydrochloric acid (a glass), and the solution is infused for several days until it turns brown. When it has settled, you can start etching.

The board is placed in the etching bath with the etching side down. To prevent the board from sinking to the very bottom, many radio amateurs glue a piece of foam plastic to the top side of the board with double-sided tape. If you need to etch a double-sided board, place it vertically in a tray or jar. This way, the dissolved copper will settle more easily to the bottom of the container and the etching process will be faster.

Do not let the ferric chloride solution come into contact with your clothing; it will be damaged and the stains will most likely not be removed.

Board etching option 2.
Copper sulfate + table salt.

As you probably know, copper sulfate is bluish crystals, you can buy it in hardware stores or gardening stores, in general, there is no shortage. Salt - regular coarse salt from the grocery store.

In addition to salt and vitriol, we will also need some small iron object (an iron plate, a nail, or something else), which we will place in the solution next to the board during etching. We will not go into the intricacies of chemical processes, we will only note that this process occurs with the formation of many complex salts, and an iron object placed in a solution during etching enters into this reaction and is consumed in the process. The solution is prepared from one part copper sulfate and two parts table salt.

That is, on two heaped tablespoons of copper sulfate, put four heaped tablespoons of table salt, pour in one and a half glasses hot water(70 degrees), stir until the crystals are completely dissolved, and the etching solution is ready. Do not make a mixture of vitriol and salt crystals in advance; first dissolve one component and then the other.

Etching time is approximately 40 minutes.
Even if you do not use an iron object when etching, the board will also be etched.
If bluish spots remain on the board after etching, they can be easily removed with vinegar.

Board etching option 3.
Hydrogen peroxide + citric acid + table salt.

The recipe for this solution for etching boards is simple: in 100 grams of ordinary pharmacy 3% hydrogen peroxide, dissolve approximately 30 grams of citric acid and 5 grams of table salt. Stir until all bulk ingredients are completely dissolved, and the solution is ready for use.

We draw your attention to the fact that there is no need to pour water into the solution. And lastly, this solution is not stored or reused. The amount prepared in this way is enough to etch about 100 square meters. cm copper foil with a thickness of 35 microns. For further etching, the solution is prepared again.

We hope that from these three options you will certainly choose the one that suits you best, based on what you currently have on hand.

Hello Dear friends! It’s 5:30 in the morning, today I woke up early on purpose to write something useful. And yes, today is May 9 on the calendar, so I congratulate you on this great day, Happy Victory Day!

Today we will talk about etching solution printed circuit boards which amazes with its accessibility and simplicity. Yes, today we’ll talk about how you can etch a board using hydrogen peroxide and citric acid and a little salt.

What types of etching solutions are there?

There are many different solutions for etching printed circuit boards, including popular etching mixtures and some that are not particularly popular.

In my opinion, the most popular etching solution in the amateur radio community is ferric chloride. I don’t know why this is so, maybe it’s a conspiracy of radio store sellers who specifically offer ferric chloride and tactfully keep silent about alternatives. But there are alternatives:

1. Etching copper sulfate With salt
2. Ammonium persulfate etching
3. Sodium persulfate etching
4. Etching with hydrogen peroxide and hydrochloric acid
5. Etching with hydrogen peroxide and citric acid

If you have any other options pickling solutions I would be grateful if you share them in the comments to this post.

What are the disadvantages of etching in ferric chloride?

Ferric chloride solution is good for everyone, it is not difficult to prepare and the etching process usually goes quickly. When preparing, it is very easy to figure out the concentration, which is called “by eye”. Once prepared solution is enough for dozens of circuit boards. But it has some disadvantages that are very annoying:

1. The solution is not transparent, which makes it difficult to control the process. You have to constantly remove the board from the etching solution.
2. Ferric chloride solution stains plumbing fixtures very badly. Each board etching session ends with the process of scraping off the plumbing fixtures (sink, bathtub, and anything else the solution might come into contact with).
3. It stains clothes very much. When working with ferric chloride, you should wear clothes that you wouldn’t mind throwing away, because the solution eats into the fabric very strongly, so much so that it is almost impossible to wash it later.
4. The solution has an aggressive effect on any metal nearby, even when stored in an unsealed container nearby metal objects may become rusty. Once I closed a jar of ferric chloride with a metal lid (the lid was painted), after a couple of months this lid turned into dust.

How to etch boards in hydrogen peroxide and citric acid

Although I have always been an adherent of the conservative path, despite all the advantages of the FeCl3 solution, its disadvantages are gradually pushing me to search for alternative etching mixtures. And so I decided to test the method of etching boards in hydrogen peroxide and citric acid.

On the way home I stopped at a grocery store and, in addition to groceries for have a delicious dinner I grabbed 4 sachets of citric acid, 10g each. every. Each bag cost me less than 6 rubles.

I went to the pharmacy and bought a bottle of hydrogen peroxide, it cost me 10 rubles.

I don’t have any project at the moment, so I decided to purely test the method, to understand what the big deal is. I found a scrap of foil PCB in my stash and made a few strokes with a permanent marker. This is a kind of imitation of tracks and copper polygons; it will work quite well for experimental work.

The solution is not difficult to prepare, but it is important to maintain the proportions. Therefore, pour 100 ml of peroxide into a plastic tray and pour out 30 g of citric acid. Since I had 10 g bags, I poured out 3 bags. All that remains is to salt the whole thing, add 5 g of table salt, this is about 1 teaspoon without a slide.

I noticed that you can add even more salt than required, this speeds up the process. Mix thoroughly. It is very important that you do not need to add water to the solution, so for preparation we select a container so that the solution covers the board, or we increase the amount of solution, observing the proportions.

We put our “printed circuit board” into the resulting solution and observe the process. I would like to note that the solution turned out to be completely transparent.

During the etching process, bubbles begin to appear and the temperature of the solution increases slightly. Gradually, the solution begins to turn greenish - a sure sign that etching is in full swing. In general, the entire etching process took me less than 15 minutes, which made me very happy.

But when I decided to etch another board in the same solution, a little larger in size than this one, everything turned out to be not so positive. The board was etched exactly halfway and the process slowed down very much, slowed down so much that we had to complete the process in ferric chloride.

Apparently the power of the solution is enough for the duration of the chemical reaction between hydrogen peroxide and citric acid. The process can be extended by adding and adding the required components.

Advantages of etching in hydrogen peroxide and citric acid

From the experience gained, we can conclude that this method, like others, has its pros and cons; it has both its advantages and its disadvantages.

Main advantages:

1. Easily accessible - all components can be easily found at the nearest pharmacy or grocery store.
2. Relatively cheap - all the components for preparing the solution are not expensive, less than 100 rubles. (at the time of writing)
3. Transparent solution - the resulting solution is transparent, this simplifies observation and control of the etching process.
4. Etching occurs quickly enough and does not require heating
5. Doesn't stain plumbing

What are the disadvantages

Unfortunately, in addition to all the advantages, this etching method is not without its disadvantages.

Disadvantages of etching in hydrogen peroxide and citric acid:

1. Disposable solution-solution Suitable for single use only, i.e. in progress chemical reaction flowing in it. It will not be possible to etch many boards; you will have to prepare the solution anew each time.
2. Expensive - despite the fact that all the ingredients are cheap, in the long run the solution turns out to be more expensive than the same chlorine jelly. After all, for each new board the solution will have to be prepared anew.

That's basically all the shortcomings. In my opinion, this method of etching boards has the right to life and it will definitely find its supporters and admirers. And in some cases, this method may be the only possible alternative, for example, in a remote village with a pharmacy and grocery store.

And with this I will wrap up. It’s already dawn outside and it’s time to prepare a delicious breakfast.

I once again congratulate you on Victory Day and wish you good luck, success and peaceful skies above your head!

From n/a Vladimir Vasiliev

Hi all! In this article I will talk about the simplest and cheapest way to etch boards at home. For this we need:

1. Hydrogen peroxide 100 ml 3%
2. Citric acid 30 g
3. Salt 3 g

As you can see, all components are available to everyone. We buy hydrogen peroxide at the pharmacy, citric acid and salt at the grocery store. Everything will be quite cheap - no more than 100 rubles.

Citric acid and hydrogen peroxide

Now let's start preparing the solution. To do this you need to find some plastic container according to the size of the fee. I used a regular plastic tray.

Plastic trays

Pour hydrogen peroxide into the tray, then pour in citric acid and salt. Mix everything. We can assume that the solution is ready. Before putting the board into the solution, you need to check if everything is fine with it. Namely, how the tracks are laid. To do this, we take the template that was applied to the board and the board itself and compare the drawing. If there are places where the paths break off, you need to take a marker or varnish and finish drawing them. The main thing is that the marker is indelible. This can be checked this way: it should have the inscription: permanent marker. I advise you to pay special attention to this, because if it is an ordinary marker, nothing will work.

Marker for drawing paths

Board drawn with marker

After inspecting the board, we lower it into the liquid. Nothing will happen right away; in order for the board to etch quickly, you need to heat the solution. To do this, take a pan of water and carefully lower the tray into it so that no water gets into it. And we put it all on the stove to heat. When the solution heats up (50 degrees), the reaction begins, this can be seen by the release of bubbles.

PCB etching

The etching process itself takes about 15-20 minutes, and if you don’t heat it up, it can drag on and more than an hour. When you see that all the tracks have been etched, carefully remove the board and wash it under the tap. We pour out the solution, as it will no longer work.

Tinning and drilling of boards

As a result, we get a pretty good printed circuit board; in the photo, the board did not quite turn out due to the fact that the template was poorly applied. If you do it right, you will do better.

Assembling parts onto a board

Finished device with this board (guess what it is)

As you can see, this is the cheapest and affordable way etching of boards. The only drawback is that the solution is disposable, that is, you need to make a new solution each time. Good luck to all. Kirill.

Discuss the article SIMPLE AND CHEAP METHOD PCB ETCHING