PCB etching (cheap). Etching printed circuit boards with hydrogen peroxide Etching printed circuit boards with table salt

Make a solution for etching circuit boards very easy from the usual components that can be found in any home.

I recently stumbled across the internet interesting recipe very cheap pickling solution printed circuit boards peroxide. To prepare the solution, you will need very available components with a total cost of not more than 80 rubles.
I used to etch with ferric chloride, then I switched to sodium persulfate, which does not leave stains. But the solution described below is better and faster than these two!

To prepare the solution we need:

For 40 ml pickling solution

Hydrogen peroxide
Lemon acid

Etching boards with peroxide and citric acid

Mix all the ingredients in proportions: hydrogen peroxide-100, citric acid-30, salt-5.

Unlike pickling solutions such as ferric chloride or sodium persulfate, this solution does not stain. The cost of such a solution is very small compared to the rest. The entire etching process takes no more than 15 minutes.

To draw traces on the board, I use nail polish and ink from a ballpoint or gel pen. I mix in a ratio of about 50 to 50. I take out the ball from the rod, pushing it out from the inside of the rod head with an ordinary sewing needle. Then I fill the varnish solution and ink back into the rod with a syringe. When in contact with the printed circuit board, it begins to gradually exit the rod, while drawing tracks. Do not forget to dry thoroughly before sending it to the board pickling solution.

Board etching process

We remove the varnish solution and ink with a solvent or gasoline.

That's it, the board is ready for tinning. Easy, simple and very cheap, without any ferric chloride.

How to make a solution for etching boards from copper sulfate

The solution is made in the ratio: for 500 ml of water (boiling water) 4 tablespoons of table salt and 2 tablespoons blue vitriol. With such etching, a small metal object is placed in a dish with a solution of copper sulfate. Unfortunately, I am not a chemist and I have no idea why this is being done. This solution also works quite well.

It should be noted that etching printed circuit boards very important in plastic or glass containers (by no means in metal) .

To speed up the etching, you can constantly stir the solution and warm it up a little.

P.S. The etching process can take up to 12 hours (depending on many factors). But do not worry, both solutions perform their function properly. Just look behind the board sometimes.

This is an edited repost from my LiveJournal

For etching, we need 37% hydrogen peroxide (optional) or in last resort 3% pharmacy, citric acid, table salt and hot water or microwave (if pharmacy peroxide). From funds personal protection- gloves and always tight-fitting goggles (possible for swimming), to protect the eyes.

After an unsuccessful first experience of etching with 37% hydrogen peroxide with electrolyte effervescence, red eyes and coughing (), conclusions were drawn and the concentrations were changed.

My unfortunate experience with electrolyte effervescence was very helpful. And I took note of a few things:

Etching in a hot solution goes well, very quickly. So fast it's worth the risk of boiling over.

It must be possible to drain or cool the solution.

The solution foams insanely, and this is a mega plus - because. Bulbulator is not required, it occurs naturally.

We need to be smarter and more careful.

In general, this time I did it very strictly. Firstly, I placed the container in a bucket so that in case of boiling up, it would not run away anywhere. Secondly, I did not make boiling water, but about the temperature when the first bubbles begin to appear, but does not boil. Water was 1.7 liters. 100 grams of 37% peroxide (I note that the total concentration is even lower than with pharmacy), 2 full tablespoons of citric acid (then I added 2 more), a tablespoon of table salt.

hellish gurgles

The result was not long in coming. The board was 10x15 cm (the size of a standard photo). I dropped everything, saw that it was bubbling, poured in a little more acid (the bubbling became stronger, after the second spoon nothing had changed). And went to the kitchen to drink some water. I returned, and the board is already etched!

Result

Total! Etching speed is about 2-3 minutes! The solution did not boil or run away (was less hot and less peroxide concentration). After pulling out the board, the solution continued to seethe and live its own life.
In general, summarizing:

It is necessary to poison in small concentrations, but with a very hot solution. For pharmacy peroxide, heat OPEN in the microwave.

It is necessary to be able to either quickly cool the solution (by pouring into it cold water), or dispose of it by pouring it into the sink. Therefore, the use of low dishes, such as plates, is not suitable! Only with high sides.

You need to follow the solution, or make such infernal adaptations, like mine

To poison ONLY in a vertical container!

In general, I advise you to use hydrogen peroxide for etching. It poisons quickly, cleanly and affordable. Doesn't stain clothes. If anything, the stains are all wiped with vinegar.

Z.Y. Etching speed is very important when etching such small parts!

conditions using hydrogen peroxide. Everything is very simple and does not require much effort.

For work, we need the following list of tools:
- Program - layout 6.0.exe (other modification is possible)
- Photoresist negative (this is a special film)
- Laser printer
- Transparent film for printing
- PCB marker (if not, you can use nitro varnish or nail polish)
- Foil textolite
- UV lamp (if there is no lamp, we are waiting for sunny weather and using the sun's rays, I have done this many times, everything works out)
- Two pieces of plexiglass (you can use one, but I made two for myself) you can also use a CD box
- Stationery knife
- Hydrogen peroxide 100 ml
- Lemon acid
- soda
- Salt
- Smooth hands (required)

In the layout program, we make the layout of the board

We carefully check it so as not to confuse anything and put it on print

Be sure to put all the checkmarks on the left as in the photo. The photo shows that we have a drawing in a negative image, since we have a negative photoresist, those areas that UV rays hit will be paths, and the rest will be washed off, but more on that later.

Next, we take a transparent film for printing on a laser printer (available for sale), one of its sides is slightly matte and the other is glossy, so we put the film so that the pattern is on the matte side.

We take textolite and cut it to the size of the required board

Cut the photoresist to size (when working with photoresist, avoid direct sunlight, as they will ruin the photoresist)

We clean the textolite with an eraser and wipe it so that there is no debris left

Next, tear off the protective transparent film on the photoresist

And carefully glue it to the textolite, it is important that there are no bubbles. We iron well so that everything sticks well

Next, we need two pieces of plexiglass and two clothespins, you can use a CD box

We put our printed template on the board, it is necessary to put the template with the printed side on the textolite and clamp it between the two halves of the plexiglass so that everything fits snugly

After we need a UV lamp (or a simple sun on a sunny day)

We screw the light bulb into any lamp and set it above our board at a height of about 10-20 cm. And turn it on, the illumination time from such a lamp as in the photo at a height of 15 cm is 2.5 minutes. I do not advise longer, you can ruin the photoresist

After 2 minutes, turn off the lamp and see what happened. Paths must be clearly visible

If everything looks good, proceed to the next step.

We take the listed ingredients
- Peroxide
- Lemon acid
- Salt
- soda

Now we need to remove the non-exposed photoresist from the board, it must be removed in a solution of soda ash. If it doesn't exist, then you need to make it. Boil water in a kettle and pour into a container

Pour in plain baking soda. You don’t need much for 100-200 ml 1-2 tablespoons of soda and mix well, the reaction should begin

Let the solution cool down to 20-35 degrees (you can’t put the board in the hot solution right away, the entire photoresist will come off)
We take our fee and remove the second protective film NECESSARILY

And we put the board in the COOLED solution for 1-1.5 minutes

Periodically we take out the board and rinse it under running water, gently cleaning it with a finger or a soft kitchen sponge. When all the excess is washed away, such a fee should remain

The photo shows that it was washed off a little more than necessary, probably overexposed in the solution (which is not recommended)

But it's okay. just take a marker for printed circuit boards or nail polish and cover up all the missteps with it

Next, pour 100 ml of Peroxide into another container, 3-4 tablespoons of citric acid and 2 tablespoons of salt. Recently discovered on the Internet new method etching of printed circuit boards, which differs from the classical etching methods, in addition, this method does not have the characteristics of traditional ferric chloride And ammonium persulfate shortcomings. Ferric chloride, with its non-washable stains on clothes and, as a result, with damaged things, may not have suited many for a long time. Also ammonium persulfate, not everyone has a separate pickling table at home - soldering, most likely most poison, like me, in the bathroom. Sometimes, as a result of careless actions with ammonium persulfate and drops on clothes, small holes form over time, things become damaged.

Some may say that persulfate suits me because of its etching speed, and so, the new etching method allows you to etch boards, I think with no less speed. Yesterday I etched the fee for half an hour, the drawing was drawn on hastily marker, the narrowest paths were 1 mm wide, no undergrass was noticed. The photo of the board is below, though after I tinned and soldered all the details to the board, just to show that even narrow paths are obtained without undercuts, I think this is enough. But I want to note right away that the drawing transferred to the printed circuit board by the method LUT (laser ironing technology) is preserved better, people, according to reviews, when etching with this method, even narrow tracks 1 mm wide are consistently good.

Now let's get down to business. On a board with dimensions of 35 * 25, which I poisoned, I spent the following ingredients: bottle of pharmacy hydrogen peroxide 50 ml, worth 3 rubles and 1 sachet 10 grams food grade citric acid, costing 3.5 rubles, salt teaspoon(used as a catalyst) of course for free, any one you have in your kitchen will do, even iodized. The exact proportions are not required here, we make something like this solution: pour hydrogen peroxide so that the board is hidden by 5 mm, add 10 grams (in my case, a bag) of citric acid and put a teaspoon of salt .

It is not necessary to add water, the liquid is used the one that is in the peroxide. If you plan to etch a large board, then we increase the amount of ingredients in those proportions relative to hydrogen peroxide, as indicated above, also so that the board is hidden by 5 mm. By the end of etching, the solution will turn blue. During etching, we move the board in containers, because gas bubbles will accumulate on the board, preventing etching.

Toward the end of etching, we remove the board from the solution with tweezers and inspect it. If we draw a drawing with a marker, then I recommend drawing in several layers to avoid small undercuts on narrow paths, but ferric chloride and ammonium persulfate will give us the same effect. The solution remaining from etching can be poured into the sewer, skipping after a large number of water. Store solution for reuse, I think no one will, it is always easier to make a new solution if necessary than to wait longer when pickling with an old solution.

Saving time and money in comparison with the old methods, I think it is obvious to everyone. You can also use concentrated peroxide sold in hairdressing stores or hydroperite tablets, but here the ratio of ingredients will have to be selected by everyone himself, since he did not experiment with them. I post, as promised, a photo of the board etched by this method, I made the board in a hurry.

A little more about this useful thing, how vertical baths. If uniform and high-quality bilateral etching is required, vertical baths with solution mixing are convenient. Mixing is done by introducing a tube from an aquarium aerator into the bath. Also, the vertical bath has a minimum evaporation area. In addition, there will be no sticky dirt if the mortar is old and littered. I wish you successful pickling without undercuts. was with you AKV .

Discuss the article PCB ETCHING

AND citric acid- a recipe that is especially popular with radio amateurs. It is not only fast but also safe way get a canvas ready for soldering the elements of the future device.

How have boards been poisoned in the past?

In the past, it took a lot of effort to get it done. First, the scheme was drawn on paper, then holes were made in the workpiece, after which the tracks were transferred to foil textolite or getinax, using paintwork products. After the coating had dried, it was torn off, and the board was immersed in a container with a meadow for etching.

The hardest thing was to poison the board. Since for these purposes a meadow was used on the basis of such a tool. In the radio circle, such a tool was not in short supply, but at home it was necessary to look for an alternative, which was most often copper sulphate.

The processing of the board carried another secret: the board was etched unevenly. Some tracks were corroded, and in some places the surface was not etched. All due to the inexperience of the craftsmen or the repeated use of the puddle solution.

Modern board processing methods

Etching the board with hydrogen peroxide is not new. Many have heard of this method before. By choosing this board preparation option, you will discover many advantages over ferric chloride etching. For example, the quality of processing, the safety and environmental friendliness of peroxide in combination with an oxidizing agent.

Recipe processing board at home

Everything you need to etch the board with hydrogen peroxide and citric acid, you will find in your first aid kit and in the kitchen, or you can easily purchase it. Another indisputable advantage of processing boards in this way is the cost of the ingredients to create the solution. Here is another advantage of the hydrogen mixture - it will cost much less than ferric chloride.

Component composition

3% - 100 ml.
Citric acid - 30 grams.
Table salt - 5 grams (as an auxiliary component of the reaction).
Water (if necessary).

Important! A solution prepared in this proportion is enough to etch copper foil with a thickness of 35 microns and an area of 100 square meters. cm.

Board preparation

Draw and print the board.
Cut out required sizes piece of textolite.
Transfer the toner to the textolite and leave to soak, then remove.

How to prepare a solution?

Heat the hydrogen peroxide: put the bottle in a water bath and wait until the temperatures of the two substances are equal.
Take a cup. Any, but not metal, will do.
Pour the heated peroxide into a clean, dry bowl and pour in the citric acid.
Stir the mixture thoroughly.
While stirring, add salt, which in the solution plays the role of a catalyst.

How to charge a fee?

To make the etching of the board with hydrogen peroxide and citric acid faster, you can use two containers. Just place the smaller meadow container in the container bigger size and pour into it hot water. This will speed up and intensify the process.

The board is etched in hydrogen peroxide solution as follows: the board is placed in the meadow with the side on which the paths are drawn down, so that the decomposition products easily sink to the bottom of the container. In order for the reaction to proceed more evenly, the solution should be stirred slightly from time to time. The whole process takes no more than 10 minutes.

Upon completion of the weed, the board must be neutralized and rinsed under running water.

This method of processing the board is completely safe. It is now possible to make boards at work, at home, and in the office, and it is not at all necessary to work with unsafe reagents.

Important! If the solution foams a lot, then you poured too much salt. Add more peroxide, otherwise the reaction will be too active, the tracks may be damaged.

If during the reaction you pull the board out and look at it, you will not be able to notice the differences, compared to how the printed circuit board is etched in ferric chloride, there are simply none. The main difference is a fast passing reaction and a less dangerous process for humans.

How to understand that the board has already been etched?

In a hydrogen-acid medium, the reaction proceeds according to the formula: Cu + H3Cit + H2O2 → H + 2H2O. The etching of a printed circuit board in hydrogen peroxide can be considered complete if any reactions have stopped in the solution: it no longer hisses or bubbles.

The finished board is cleaned and washed with water. Toner or paint can be removed with acetone. After that, the board is thoroughly wiped and degreased.

Important! Check the tracks for integrity after processing the board. A damaged circuit will not work.

As you can see, etching the board with hydrogen peroxide at home is not only possible, but also safe. It won't be hard to find necessary components for the preparation of an etching composition, and the process itself will take no more than 15 minutes. Today, any radio amateur, thanks to simple and accurate advice, will be able to experiment at home without harming himself or others.