Ferric chloride from the powder to get a solution. iron chloride. Concept, properties and application. Scope of ferric chloride

Synonyms: Ferric chloride (iron chloride solution), ferric chloride.

Description: A solution of ferric chloride is a caustic, non-volatile brown-brown liquid. The product complies with the requirements of STO 00203275-228-2009

Chemical characteristics of ferric chloride

Depending on the time of year, air temperature, ferric chloride is produced in 1 or 2 grades.

Physical characteristics of ferric chloride

Molecular weight: 162.21 g/mol

The boiling point ranges from 100-106°C.

The pH value is approximately equal to from 1 to 2.

When etching copper in a solution of ferric chloride, the maximum dissolution capacity is 100 g / 1 l. The etching rate at 50–55°C is 4.3–5 µm/min.

The densities of aqueous solutions of iron chloride are shown in Fig. 1:

Scope of ferric chloride

Ferric chloride is used in industries such as: sewage treatment plants, water utilities, metalworking, chemical, food, brewing, leather, oil, etc.

The main use of ferric chloride solution is in the purification of industrial and Wastewater, as a primary coagulant. Under the action of ferric chloride, a physicochemical process of enlargement, adhesion of small particles (coagulation) occurs, which contributes to the precipitation of a flocculent precipitate from the colloidal solution, or the formation of a gel, which, later, is easily removed from the treated wastewater. When cleaning with ferric chloride, the amount of insoluble impurities in wastewater is reduced to 95%, soluble to 25%.

Compared with some coagulants, ferric chloride has a number of advantages, these are:

• a sufficiently high rate of deposition of impurities.
• positive effect on the biochemical decomposition of precipitated impurities, activated sludge.
• lower cost compared to other common coagulants.

Ferric chloride is also used:

• as a catalyst in organic synthesis processes.
• for etching metals (printed circuit boards, printed forms)
• as a mordant when dyeing fabric.
• as an additive to increase the strength of concrete.

Ferric chloride hazard class

Ferric chloride solution is a caustic, non-volatile, corrosive liquid.

Fire and explosion proof.

Upon contact with the skin, ferric chloride causes irritation, itching, dry skin, dermatitis. If it gets into the eyes, it causes irritation of the mucous membrane. Rinse skin or eyes immediately with plenty of water and seek medical attention if necessary. When working, it is necessary to use personal protective equipment.

UN number 2582

Packing, transportation and storage of ferric chloride

Transported by any mode of transport in accordance with the rules for the transport of dangerous goods in force for this mode of transport.

The solution is transported in rubber-lined steel railway or truck tanks, as well as in special containers with a capacity of up to 1000 dm3.

Ferric chloride should be stored in rubber, titanium or polyethylene containers.

In the cold season, the product is stored in closed warehouses in compliance with the temperature regime.

Guaranteed shelf life - one year from the date of manufacture.

It is not subject to mandatory certification.

Attention! I myself have not tried that method, I just read about it in some book!

For the manufacture of ferric chloride, you need to take iron sawdust or thin plates and fill them with a solution of hydrochloric acid (HCl).

Sawdust is left for several days in an open container. After a few days, the solution will turn green.

After that, the resulting solution is drained and after a while it is ready for "work"!

P.S. On July 13, 2007, we received a letter from the respected Vladimir Syrov, in which he wrote the following:

For decades, a story about the possibility of making ferric chloride at home has been wandering around amateur radio literature. Here and on this site there is such (see above).

An unknown author honestly says "I myself have not tried this method." But, apparently, NONE of those who have ever written about it have tried this method !!! And your obedient servant tried it in the 90s, and the results are such that it is better not to even try to do it.

Iron can be either trivalent or divalent. When combined with chlorine, two formulas are obtained - "ferrum chlorine two" and "ferrum chlorine three". The first is green crystals, the second is yellow-brown. Only ferric chloride is suitable for etching copper printed circuit boards, "ferrum chlorine two" does not work - it has been established by experience. Or at least not working well. And with the described artisanal method (pouring iron filings with hydrochloric acid), according to some laws of chemistry, it is precisely "ferrum chlorine two" that is obtained. In some more detailed publications on this topic, this fact seems to be taken into account - they write something like "if you get a greenish
solution - let it stand in the open air so that it becomes yellowish-brown. "It has been verified by experience - it does not work! It stood for weeks and months ... Some insignificant part of ferrous iron is oxidized to ferric, but no more.

I tried to heat the solution, evaporate it, dry it and leave greenish crystals in the air .... To further oxidize by passing oxygen first through the solution, and then chlorine .... Everything is useless! I almost got poisoned myself and did not poison those around me, but I never got a practically significant result, a noticeable yield of "ferrum chlorine three"!

Please pay attention to the fact that we are dealing with poisons here! Hydrochloric acid is a solution of ash-chlorine gas in water. It "gases", that is, "ash-chlorine" evaporates from it. This gas, combining with water on the mucous membranes of the respiratory organs (nose, mouth, trachea and bronchi, lungs) - turns into the same hydrochloric acid! Chlorine, which I managed to get in sufficient quantities, is generally a specific poison. It is worth thinking about the fact that health is more expensive! At present, in any large city there is no problem to buy ferric chloride somewhere on the radio market and not suffer from its manufacture. As it turned out, in industry, chlorine (not chloride!) iron is obtained in a completely different way - by burning iron in an atmosphere of chlorine. It goes without saying that this method is hardly feasible at home.

Even in the presence of ready-made ferric chloride, I would advise you to be careful - to poison somewhere under air draft, on a balcony, somewhere in a garage .... To protect the health of not only your own, but also those of your immediate family. Not to mention lead, which is part of the tin-lead solder. Very small amounts of vapor
lead, getting into the body, eventually causes chronic poisoning, various diseases, including tooth decay .... It is not for nothing that there are very strict instructions for the installation of exhaust ventilation in the workplace. But at home, in everyday life, radio amateurs very often neglect this, but in vain. In fact, this lead is quite enough
A little. Only the consequences do not come immediately ... And there is little good in chlorides either ...

So the author of the publication (quoting someone) writes: "after a while the solution will turn green." It will be ferrous chloride, and not what should have been obtained. And about the fact that "after some time" it will still be ready for work .... Alas. If you don't believe me, try it yourself! And only then can you write a recipe when it
personally verified by experience. It is not worth writing from other people's words.

Faced with the process of creating printed circuit boards at home, beginners often ask a simple question on various forums about how to dilute ferric chloride. It seems that this topic is not so extensive as to dedicate a whole extensive article to it, but after thinking a little, we nevertheless decided on a small note.

On sale you can find two types of ferric chloride:

• Hexahydrate ferric chloride. It resembles wet sand of yellow-orange color.
• Anhydrous ferric chloride. Powder or lumps of black color.

Both that and another perfectly poison textolite. The etching time with a freshly prepared solution is about 5 minutes, and with an old solution, the etching time can increase to 20 minutes or more. For clarity, we will prepare quite a bit of solution and show how to dilute ferric chloride to etch boards.

First of all, we open our container with ferric chloride. We try not to get their hands, clothes and table dirty, because. it is almost impossible to wash or wash off the fabric.

We are preparing dishes with water in which we will make a solution of ferric chloride. Dishes should be plastic or ceramic, the use of metal containers and tools is strictly unacceptable. Ideally, it is better to take distilled water, but in practice everyone manages with warm boiled water.

Pour ferric chloride into a container with water with a plastic spoon and mix constantly.

It is better to add ferric chloride half a teaspoon at a time, the solution will gradually heat up, and gases will also be released. Approximate solution ratio 1:3(i.e. one part ferric chloride to three parts water) by weight.

The concentration can also be determined by eye, a good solution should be the color of strong tea. In fact, you can dilute ferric chloride as you like, but the rate of etching of the board will directly depend on this.

The etching process itself is best done in a slightly heated solution. After etching the boards, the spent ferric chloride solution must be stored in a dark place in a sealed container until the next use.

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In contact with

Ferric chloride is one of the most common reagents for etching printed circuit boards. The solution is not aggressive, such as nitric acid, but has sufficient strength to become an order of magnitude higher than the solution of copper sulfate and other hydrogen peroxides with citric acid. Therefore, when it became necessary to make a small printed circuit board, my choice was obvious. But then a surprise awaited me - there was no ferric chloride in our city. "It's been gone for a long time," said the saleswoman of one of the radio shops. I had to take it on the Internet, I still ordered radio components. The price came out 40 UAH. (≈$1.7) for 250 grams. Taking into account the fact that I do something infrequently, due to lack of time, this amount of ferric chloride will last me for a long time.

Well, the courier services are on schedule, we didn't have to wait long. Packing is made in PET soda bottle. The bottle was opaque and it was impossible to see the volume. Everything looked like this:

For storage, I find it very convenient. Having crumpled the bottle in my hands, I realized that I had a pasty substance inside and it would not let me leave the bottle so easily. He unscrewed the lid, made sure that it was exactly ferric chloride inside (you will never forget its smell again) and set about searching for the necessary container.

The choice of container for the storage and use of ferric chloride must be approached responsibly. For work, it should be comfortable, for storage - safe.
You need to know that as a result of chemical reactions, chlorine and hydrochloric acid will constantly volatilize from the solution. All these substances are poisons. It is necessary to work with ferric chloride in well-ventilated areas (preferably in the open air), it is also forbidden to lean directly over the vessel with the solution in order to avoid inhaling toxic substances. I advise you to store it in a hard-to-reach (well, well-ventilated) place so that neither a child nor a kitten can turn over, break, spill the working solution. (I will talk about the consequences later in the text).

Having compared all the facts, I chose a plastic food tray as a vessel.

Now one of the most important questions - what proportions to choose? I didn't bother with that! The etching rate depends on the concentration of pure ferric chloride and the temperature of the solution. Add more - it will be faster to pickle and vice versa (you can add it at any time, but over time it is easier to replace the solution with a completely new one). Ferric chloride is highly soluble in water, so you can achieve such a concentration that etching will take up to five minutes.

I poured 0.5 liters into the tray. warm water and squeezed into it about half a bottle of ferric chloride (≈125g. ), stirring constantly. It wasn't easy to squeeze out. The result is a solution as in the photo below.

I decided to work in a bathroom with forced ventilation. I don’t have a photo, but I strongly advise you to put the solution on cellophane or disposable bags and throw them away when you are done. This also applies to storage! Having spilled the solution on a tile, table, linoleum, you will have to make a lot of effort to clean them. The greater the production of the solution, the more difficult it will be to clean.After contact with the tissue, in most cases, it will have to say goodbye. Based on this, it is impossible to pour mining into the sewer. Firstly, it is poison, and secondly, the snow-white toilet bowl will turn brown-rusty. This must be kept in mind!

The solution I got etched a small fee in 15-20 minutes. During this time, I mixed it a couple of times, especially at the end, when the copper from the board began to disappear before our eyes, until it completely disappeared.

I store such things on the balcony, in the far corner of the rack. Nitric acid lives in the neighborhood, but I use it when, for example, I need to make a small board with wide tracks. In some places, it corrodes the toner, does not see the permanent marker - you have to draw with bituminous varnish, which is not very convenient. But as they say, everything has a purpose!

All chrome on our parts appears as a result of galvanic chromium plating.

Chrome plating- is an electrochemical method of applying metal coatings to plastic. The bottom line is that three layers of metal are applied: copper + nickel + chromium. Chromium reacts and evenly settles on the surface of the product. This type of chrome plating is used for car emblems, radiator grilles, souvenirs, etc. and so on.

How do you get rid of this chrome?

There is an option to actively work with sandpaper, but very often the details are never even, with many small elements. To skin such - hands will wither. That is why chemistry, which we love to play truant at school, will help us!
The easiest way is to put our plastic part in a solution of ferric chloride for a while and pickle it like a printed circuit board.

Ferric chloride

What is ferric chloride?

Ferric chloride FeCl3 is an average salt of ferric iron and hydrochloric acid. In appearance, this chemical raw material is a soft crystalline mass of a rusty-brownish-black color. It is used for etching printed circuit boards in the electronics and instrumentation industries.

Cooking.

It is customary to prepare a solution of ferric chloride based on a ratio of 1 to 3 (1 part of iron to 3 parts of water) by weight.
The solution should be prepared in a heat-resistant non-metallic container, into which water is poured with a temperature of about 60-80 degrees. Of course, it is advisable to use boiled water, but ordinary tap water does an excellent job with this task. According to science, you need to use distilled water, but in practice, no one bothers with this - we do not have a chemical laboratory!
Ferric chloride must be poured into water (! in no case not vice versa!) In small portions, continuously stirring the solution. When dissolved, the water will heat up and a rather violent reaction will be visible (seething, hissing, release of steam, which is highly discouraged from inhalation). It will take about 20 minutes to dissolve (it all depends on the volumes), but the iron will dissolve completely and will not settle to the bottom of the container, nor will the solution boil or the container melt. One piece of advice - don't rush!
After dissolution, it is necessary to allow the solution to settle. After 20 minutes it will be possible to observe the settling of iron hydroxide (rust) on the bottom, which is always contained in ferric chloride powder and which prevents etching. It is better to give a solution
stand for 10-12 hours, so that any debris, which is often present in ferric chloride, settles to the bottom of the tank. After the solution has settled, it must be filtered into a clean container, in which it will actually be stored. The solution can
easy to use repeatedly, and it is stored for an arbitrarily long time.
As a result, we got a clean, transparent, brown solution of ferric chloride.

Etching result:

Etching result

Solution recovery

Each time after use, the solution will lose its strength and subsequent etching will last longer. Again, heating and stirring the solution will help speed up the etching process.
The solution can be restored by adding hydrochloric acid to it - part of the hydroxide again
reduced to ferric chloride. But the easiest way is terribly banal - we throw a few ordinary nails into the solution, copper will settle on them from the solution and the solution will gain strength again. But you should not abuse this, especially when the solution is new - the solution can degrade and gradually change color from brown to green.
There are several more recovery methods, but provided that we do not need the solution on an industrial scale, I will not describe them.

Conclusion

In closing, I would like to warn you: be very careful with ferric chloride!
I recommend carrying out all work with gloves - ferric chloride eats well into hands and is poorly washed off with soap, if it gets on the skin it can cause itching and irritation, up to burns in people with sensitive skin. In case of contact with eyes, rinse them big amount running water and of course consult a doctor.

Peace for everyone!

PS Photos found on the internet (Belarusian BMW club, google, yandex)

For the manufacture of a printed circuit board, a copper-dissolving reagent is required. The most common, and relatively harmless, is ferric chloride. It can be purchased at a radio parts store. The bank looks like this:

Instructions for cooking are written on the label, pickling time of 40-50 minutes attracts attention. Perhaps for some it will seem normal.
About 15 years ago, such cans simply were not sold. Therefore, radio amateurs themselves prepared a solution of hydrochloric acid and rust. The resulting solution of ferric chloride etched copper in 5-15 minutes at room temperature. Of course, this is true for a fresh solution. After a year of its use (about 10 times a month), the solution was poisoning for an hour or two.
It is very strange then to wait an hour to make a board, if it can be done in 5 minutes. The etching rate depends on the concentration of the solution. This is true for the first use. Therefore, if we dilute 250 grams per liter of water, we get an hour of pickling, and if it’s half a liter, it’s apparently much less. True, it’s not known for what size of the board the pickling time is indicated on the bank.
I am not satisfied with the manufacturer's advice, I consider it stupid to wait so long. I will show you how I usually prepare the solution
Open the jar and see what's inside.

I have this. It looks like the powder (if you can call it that) is fresh. If there is “syrup” in the jar, then it pulled dampness, or maybe it was like that from the factory. Usually I do it by eye, but this time I decided to document it. It is advisable to use a plastic spoon, as aluminum dissolves. I didn't have it.

You will need a half-liter glass jar, a nylon lid (it is advisable to check it fits the jar in advance), water, a spoon. IN this case the solution was prepared in a ratio of 1:2. 1 part ferric chloride, 2 parts water. Stir the solution well, let it stand for half an hour.

Let's start etching. Heating significantly speeds up the process. It is desirable to heat no higher than 60-70 degrees. By eye, this is when steam comes out of the liquid. For these purposes, I use an enameled iron bowl. The service life of the dishes is two years, with active use. Then holes form in it.

Before putting the board into the solution, it is advisable to moisten it with water. This will save you from a very big annoyance in the form of small bubbles, which in the end can create a closure between the tracks or ruin aesthetic appearance. I didn't do it in the photo.

I pour the solution, and start the stopwatch. You need to heat on a very slow fire. The solution heats up quickly.

Voila! The payment is ready.

For such an area of ​​the printed circuit board, the process took no more than 5 minutes.

Attention!
Splashes of the solution that have fallen on objects must be removed immediately with a damp cloth or sponge, rinse the place of contact well. Avoid getting the solution on the plate. Wear "work" clothes. Droplets on clothes will lead to the formation of non-removable rust stains. Work with the hood turned on.

Ferric chloride is the most effective PCB etching chemical, but very expensive. You can cook it with your own hands in rubber gloves according to recipes written out from the Radio magazine.

Methods for the preparation of ferric chloride

For the preparation of ferric chloride used in the etching of printed circuit boards, we used powdered iron minium and technical hydrochloric acid, which are commercially available. For one (by volume) part of hydrochloric acid, 1.5-2 parts of red lead are required. The components are mixed in a glass promise, adding red lead in small portions until the end chemical reaction, as a result of which a solution of ferric chloride is formed, ready for use, and a precipitate falls to the bottom. The preparation of ferric chloride must be done in the open air, observing the precautions of V. BATSULA. V. KUZIN Sevastopol

In "Radio" (1990. No. 8, p. 74) a note by A. Sergienko and V. Ivanenko "Preparation of ferric chloride" was published, which tells how to prepare iron trichloride for etching circuit boards under amateur conditions. The essence of this method is the treatment of ordinary rust with hydrochloric acid. However, gaining the required amount of rust is not as easy as it seems. In addition, it inevitably contains a lot of "dirt" that spoils the final product. I solved this problem chemically. When iron sulfate is calcined on fire (it can be purchased at stores selling household chemicals or garden supplies), water first evaporates from it and a white mass of anhydrous iron sulfate salt remains. With further heating (at a temperature of more than 400C), the mass decomposes with the release of gaseous sulfur oxides, which form sulfuric acid vapors in the air. Therefore, work must be carried out under a good hood or in the open air. In the process of calcination, it is necessary to crush the sintering mass. After some time, it turns into a fine rust powder of fairly high purity. Store the powder in an airtight container, as it is hygroscopic and because of this it cakes into lumps. The chemical rationale for the rusting process is set out in study guide Glinka N. L. "General Chemistry" (for example, 1975 on p. 680)
V. ZABIRONIN, Lutsk, Ukraine

The magazine has already published several options for the formulation of a ferric chloride-free PCB etching solution. And yet, many people prefer to process boards in a solution of ferric chloride, since etching is much faster in it. Unfortunately, ready-made ferric chloride remains in short supply, and this forces radio amateurs to look for ways to prepare it on their own (some of them were also described in the magazine). We offer another fairly simple way to make ferric chloride at home. This will require technical hydrochloric acid, sold in household goods stores, and iron dioxide - rust. About 1 liter of acid is poured into a three-liter jar, observing the necessary precautions, and a little iron dioxide is poured into it until the reaction stops. After settling, the solution must be poured into another container - it is ready for pickling. It is desirable to carry out work outside the living quarters, since during the reaction a large amount of foam and gases with an unpleasant odor are released, and there may be acid residues in the foam.
A. SERGIENKO. In IVANENKO, Artemovsk, Voroshilovgrad region.

If there is no ferric chloride in finished form (in powder), then you can cook it yourself. To do this, you must have 9% hydrochloric acid and fine iron filings. For 25 parts by volume of acid, one part of iron filings is taken. Sawdust is poured into an open vessel with acid for several days. At the end of the reaction, the solution becomes light green, and after five to six days the color changes to yellow-brown - the solution of ferric chloride is ready for use. For the preparation of ferric chloride, you can use powdered iron minium. At the same time, 1.2-2 parts of red lead are required for one volume part of concentrated hydrochloric acid. The components are mixed in a glass dish, adding red lead in small portions. After the cessation of the chemical reaction, a precipitate falls to the bottom - the ferric chloride solution is ready for use.

During the etching of printed circuit boards, the ferric chloride solution gradually loses its activity, and the etching rate decreases. This is explained by the fact that the solution is saturated with copper ions.
Usually such a solution is drained. However, you can restore its activity in a simple way. Several large steel nails must be immersed in the spent solution. After some time, excess copper from the solution will settle on the surface of the nails and on the bottom of the vessel. After that, the solution is poured into another vessel, the copper is removed from the pickling bath, the nails are cleaned, and then they are put back into the bath and filled with the same solution. As copper accumulates on nails, it is removed. Thus, it is possible to significantly extend the "life" of a solution of ferric chloride.
V. KOLOBOV, Lyubertsy, Moscow Region

"Normal rust" is practically unsuitable for the manufacture of ferric chloride. Especially iron filings or pieces of iron - checked! It is necessary to take rust that separates from iron in layers - it forms in a very humid atmosphere (mine, basement, etc.). This rust consists of oxide + ferrous oxide, which is what is needed. For 0.5 liters of hydrochloric acid (sold in hardware stores), you need to take 1.5 cups of crushed (0.3 - 0.5 cm) rust by volume. All this is placed in 1 liter. glass jar and add 25 ml. acetone (catalyst). It is acetone, not some solvent. Cover the jar with a piece of glass. Stir 3 - 4 times in a couple of days - and you will have ferric chloride better than the factory one.

Ferric chloride (ferric chloride, iron trichloride, FeCl 3) is a chemical reagent, which includes hydrochloric acid and ferric iron. Ferric chloride is a soft, crystalline violet, green, brownish-reddish or dark brown color with a metallic sheen and is hygroscopic. When interacting with air, it resembles wet sand - it acquires a yellowish tint. The formed hydrates are readily soluble in water, ether, acetone and alcohol. The interval from the boiling point to the melting point is from 319 ° C to -309 ° C. Molisite (mineral) is a natural source for the production of ferric chloride. The simplest method for obtaining this chemical reagent is to heat the gland with chlorine to a certain temperature. As a by-product, it is obtained as a result of hot chlorination or oxidation of FeCl 2 with further evaporation of ferric chloride.

Applications

Thanks to his unique composition The chemical reagent has found its wide application in many industries:
- textile (when dyeing fabrics);
- chemical (in the manufacture of iron pigments and other iron salts);
- electronic (when working with printed circuit boards);
- environmental (for wastewater treatment);
- food (improve flour, when making bakery products);
- publishing industry (as a reagent in photography);
- jewelry production;
- metallurgy (in metalworking);
- brewery.

Ferric chloride in pharmacology and medicine

Ferric chloride is an indispensable element for the normal functioning of the body. Its deficiency can lead to serious diseases. Thanks to iron in the form of salts, the body is quickly replenished with it and takes part in the following processes:
- is an additional source of iron in the body (with its low content - anemia);
- regulates redox reactions (binds oxygen), stimulates erythropoiesis;
- restores blood loss in injuries;
- with a decrease in iron absorption (during a period of intensive growth, during pregnancy);
- to stop bleeding (put a cotton swab with a solution on the wound).

Ferric chloride precautions

Given the strongly colored effect when in contact with chlorine iron should be remembered: in order to avoid darkening of the teeth, a drug based on such a chemical reagent should be taken inside only through a tube. When changing the stool, a single dose should be reduced, but the frequency of administration should be increased. It is not recommended to take the drug for violations of the function of the gastrointestinal tract. In case of contact with ferric chloride on the skin, wash well with soap and water. In case of contact with mucous membranes, it can cause burns. It is recommended as first aid - abundant washing with clean water, then - treatment by a doctor.

You also need to remember that this chemical reagent is flammable and explosive. It is necessary to store ferric chloride in a closed package away from sunlight and heating devices.

Obtaining ferric chloride at home or in the laboratory

1 way. Put ordinary rust into laboratory glassware or laboratory glassware and dilute with hydrochloric acid in a ratio of 1:3. The resulting chemical reagent (a characteristic feature is a yellowish-brown color) is drained after 2-3 days and, if necessary, passed through filter paper.

2 way. Hydrochloric acid is poured into glass laboratory glassware and iron minium is added in small portions. It is important to remember that when working with caustic chemicals, and hydrochloric acid also belongs to them, safety measures should be observed. Laboratory work should be carried out in examination seals or nitrile gloves, an apron and a protective mask.

After the laboratory work the room should be well ventilated, since iron vapor can cause damage to the respiratory system, vision and skin.

Where to buy ferric chloride in Moscow?

The ideal store where you can buy ferric chloride in Moscow is the Moscow retail chemical reagents store Prime Chemicals Group. Our online store presents all types of laboratory equipment and instruments, laboratory glassware, laboratory glassware, rubber products, laboratory glass. All products have passed quality control at the manufacturing plant and meet all GOST standards.

We recall the ratio of components in a solution of ferric chloride used in the etching of printed circuit boards. Ferric chloride solution: 200 ml of water H 2 0 is taken per 150 g of FeCI 3. Etching time is 5-10 minutes.
Although ferric chloride is not poisonous (in its pure form, it is used in medicine to stop bleeding by applying cotton wool with its solution to the wound), but it leaves very difficult stains. As a stain remover, a concentrated solution of oxalic acid is recommended, which should be abundantly moistened with a rag and put on the stain for tens of minutes. Then this place is washed with water.

Recovery of ferric chloride. With repeated use of the same solution, it becomes covered with dark spots, loses its etching qualities. To restore it, it is necessary to lower pieces of iron (nails, screws, sawdust). After a few days, they will be covered with an anti-corrosion layer of copper and they can be used for their intended purpose, and the regenerated solution should be filtered and ready for further use.

In the absence of ferric chloride, an etching solution can be obtained at home in several ways.

1. In plastic or glassware, 3 parts of hydrochloric acid should be taken for 1 part of ordinary rust by weight. After a few days, most of the rust dissolves and the solution acquires a characteristic yellow-brown color. It is carefully drained from the sludge lying at the bottom and, if necessary, filtered through a cloth placed on the neck of a glass jar.

2. Pour one third of the HCI solution into a glass dish and add minium iron in a total amount of about 1.5 parts by volume in small portions, the entire solution is thoroughly mixed. chemical process comes with the release of gases, so the room must have exhaust ventilation or be well ventilated. The solution is left for several days in the open air, upon completion of the reaction, ferric chloride precipitates, the top layer is drained, and ferric chloride is used for its intended purpose.

3.Solution for etching printed circuit boards based on hydrochloric acid and hydrogen peroxide. For preparation, a 30% solution of hydrogen peroxide, hydrochloric acid with a density of 1.2 and water are taken, all this is mixed in a glass dish in a ratio of 2: 2: 6 parts, respectively. If pharmacy hydrogen peroxide is 16-18%, then the ratio of the mixed parts is 2:4:4, respectively. The etching time with such a solution is up to 10 minutes.
In the event that instead of a hydrogen peroxide solution there is hydrogen peroxide in tablets, the recipe for preparing an etching solution is as follows: 5 tablets of hydrogen peroxide are dissolved in a glass of water H 2 0 (250 ml), then the resulting solution is poured into a glass dish and 15 ml of a solution of concentrated hydrochloric acid HCI, mix it all up and the solution is ready for use. The etching time of printed circuit boards with such a solution is up to 1 hour.

4. Alkaline pickling solutions (dissolve untinned copper, practically without affecting tinned tracks)

1st squad
Copper sulfate CuS04.........170.. 190 g/l
Ammonium sulfate (НН4)2ЗО4150..170 g/l Aqueous ammonia 25% pacTBopNH4OH..500 ml/l

2nd squad
Copper chloride 11 CuCI2.........100.. 110 g/l
Ammonium chloride NH4CI ........ 150..170 g/l
Aqueous ammonia 25% NH4OH 400..500 ml/l Ammonium bicarbonate (MH4)2CO3....20..30 g/l

5. Well, the traditional most non-deficient solution of copper sulphate and table salt, per 500 ml: NaCI - 4 tablespoons, CuSO4 - 2 tablespoons. Etching time is about 8 hours.