Rose alloy what is it

Rose alloy: what is it, composition, application

If you take tin, lead and bismuth in proportions 1:1:2 and get an alloy, then it is called Rose’s alloy, or more precisely Valentin Rose the Elder, a German pharmacist and part-time chemist. Note that if the melting temperature (i.e., the transition from a solid crystalline state to a liquid) for tin is 231.9 degrees Celsius, then for the Rose alloy it will be about 94-98 degrees Celsius.

It would be fair to note that the championship in the discovery of the composition of elements for a low-melting alloy belongs to Sir I. Newton, who in 1701 recommended the proportion of these elements 2: 3: 5. Valentin Rose dared to deviate from this recommendation 45 years after the departure of the one who “in intelligence surpassed the human race.”

Rose's alloy is often confused with Wood's alloy, as they are similar in appearance.

But Wood’s alloy, on the one hand, has a lower melting point (68.5 degrees Celsius), and on the other hand, this is due to the cadmium added to the composition, which is a toxic and carcinogenic element, which can only be worked with with all precautions. It is precisely because of the toxicity of cadmium in Wood's alloy that Rose's alloy has become more widespread.

POSV-50 tin cannot be soldered

In domestic radio electronics, Rose's alloy is labeled as POSV-50 - tin-lead solder with the addition of bismuth, where bismuth is 50%, the rest is equal parts tin and lead. It is also important to note that the content of elements in the Rose and POSV-50 alloys in the indicated proportions may differ slightly.

In general, the main purpose of the POSV-50 alloy and its analogues is tinning and soldering.

Soldering elements involves desoldering elements from a printed circuit board and installing the elements on a new printed circuit board. It should be noted that when solidifying in the soldering volume, the Rose alloy becomes brittle. Therefore, the resulting solder joint should not be subjected to shock loads, as microcracks may form, which will lead to the destruction of the joint.

Tinning with Rose alloy has become more widespread than soldering. The tinning process with this alloy is characterized by the fact that it can be carried out in an easily accessible medium - water with glycerin or in glycerin.

The use of glycerin is explained simply - it is needed to achieve the melting temperature of the alloy, and the alloy just begins to melt at 94 degrees Celsius, and for complete melting a temperature of 105 to 120 degrees Celsius is needed (depending on the percentage composition of the particular alloy).

Water, as you know, boils at a temperature of about 100 degrees. Performing operations in boiling water means inhaling volatile products along with the steam. Glycerin, on the other hand, has a boiling point of 290 degrees Celsius, mixes with water in any proportions, and is also gyroscopic.

This allows, when mixed with water, a guaranteed increase in the boiling point of such a mixed liquid and a reduction in vaporization.

If you mix equal volumes of water and glycerin in a solution, you will get a boiling point of the solution of 110 degrees; a solution with a 2:1 proportion of components will give a boiling point of 103.9 degrees (at normal atmospheric pressure).

To convert a solution of glycerin in water into a weakly active flux, citric acid is added to it, usually in arbitrary proportions, but not less than 1 gram per 100 ml of solution. It is advisable to use distilled water, as it contains less salts.

By the way, for the same reason, you should not use salt instead of glycerin to increase the melting point of water, because this will affect the quality and uniformity of the tin coating.

Also, the use of glycerin allows the surface tension of the solution, compared to ordinary clean water, which facilitates the process of rubbing the melt over the surface of the printed circuit board tracks.

The process of tinning with Rose alloy (POSV group of solders) is similar for Wood’s alloy:

— distilled water is poured into a special container (sufficient in size to immerse the printed circuit board at least partially) and glycerin is added in the required proportions, which are most convenient to select experimentally using any type of thermometer;

- heat the solution to a temperature of about 105 degrees Celsius, add citric acid to the solution;

— immerse the etched and cleaned printed circuit board in the solution;

— place solid particles of the Rose alloy on the required area of ​​the board and wait for it to melt (however, you can first lay the Rose alloy in a sufficient amount by eye, and then immerse the board on it - this is a matter of practice);

- rub the melt along the tracks of the printed circuit board with a wooden or plastic tool (for example, a spatula for a Teflon frying pan or a hard rubber spatula);

— after tinning, the board is washed in warm running water (with soap if possible).

It should be noted that it is better to take aluminum, enameled or cast iron cookware, because... the use of galvanized, copper, silver or tinned utensils and tools for tinning will lead to the dissolution of the utensil metals in the solder and deteriorate its quality, i.e. it will be impossible to use it repeatedly. For the same reason, only clean boards should be immersed in the solution.

It is important that utensils for tinning cannot be used for further cooking, because... Lead deposits in small quantities on machines.

It is recommended to work with rubber gloves to avoid burns.

Word of mouth from Aunt Rose

In general, opinions about the ease of use of the Rose alloy, which can be read in large numbers on radio forums, come down to two options - some use it in their tinning and soldering practice and naturally recommend it, others tried it, something didn’t work out, they had to refuse to use it and therefore are naturally not recommended. There are also those who are simply interested in trying it for some reason - they ask questions. And since the community of radio amateurs is constantly replenished with newcomers (with the spread of various kinds of gadgets - the need for such people is growing) - the exchange of opinions will continue. It is surprising that all this communication is based on a discussion of only two characteristics of the Rose alloy, as a representative of the group of tin-lead low-melting alloys - low melting point and brittleness in the solid state. Moreover, purchasing the alloy is not a problem. It is produced in the form of granules, rods or silver ingots and is sold in any stores along with radio components.

“Rockets fly, but tanks drive”

This is exactly the answer that followed to the question about the poor adhesion of the PIC solder to the track tinned in the Rose alloy on the radio cat. And this is true, given that electrical and electronic circuits are included in most so-called “smart” devices today.

In addition, it is known that Rose’s low-melting alloy is used not only for tinning, but also as a fuse in electrical networks and fire alarm systems.

Rose's alloy is also suitable for precision casting, although it is inferior to Wood's alloy when performing micro-castings.

Just like Wood's alloy, it is used in chemical laboratories to create a low-temperature heating bath.


What is rose alloy

If you take tin, lead and bismuth in proportions 1:1:2 and get an alloy, then it is called Rose’s alloy, or more precisely Valentin Rose the Elder, a German pharmacist and part-time chemist. Note that if the melting temperature (i.e., the transition from a solid crystalline state to a liquid) for tin is 231.9 degrees Celsius, then for the Rose alloy it will be about 94-98 degrees Celsius.

It would be fair to note that the championship in the discovery of the composition of elements for a low-melting alloy belongs to Sir I. Newton, who in 1701 recommended the proportion of these elements 2: 3: 5. Valentin Rose dared to deviate from this recommendation 45 years after the departure of the one who “in intelligence surpassed the human race.”

Rose's alloy is often confused with Wood's alloy, as they are similar in appearance.

But Wood’s alloy, on the one hand, has a lower melting point (68.5 degrees Celsius), and on the other hand, this is due to the cadmium added to the composition, which is a toxic and carcinogenic element, which can only be worked with with all precautions. It is precisely because of the toxicity of cadmium in Wood's alloy that Rose's alloy has become more widespread.

Alloy Rose. Soldering and tinning

Rose's alloy contains the following elements: tin (25%), lead (25%) and bismuth (50%). A deviation of ±0.5% is considered acceptable.

This alloy is used for soldering aluminum, nickel, brass, bronze, silver-plated jewelry parts and parts characterized by increased sensitivity to overheating.

Rose alloy, which is POSV-50 solder, has found its application in semiconductor technology, radio engineering and electrical fuses. The developer of the alloy is considered to be Valentin Rose the Elder, a German pharmacist and chemist.

Transportation and storage

Rose alloy can be transported both by road and by rail. Storage can be carried out not only in closed warehouses, but also in open space in hermetically sealed packaging.

Safety precautions

It is not recommended to have long-term contact with heavy metals that are part of the Rose alloy. Particularly dangerous is the ingestion of the alloy into the body. The fact is that some alloy elements, for example, lead, are characterized by high toxicity, which can cause severe intoxication of the body.

Tinning of boards with Rose alloy

The melting point fluctuates around 94 ÷ 1000 C. Consequently, even a drying oven at the place where paint and varnish coatings are applied can serve as melting equipment. With the help of Rose alloy, many radio amateurs tin the copper surface of the etched board.

When tinning with Rose alloy, you need to perform several simple procedures:

1. Pour a small amount of water (up to 500 ml) into a small container and mix a spoonful of citric acid in it, which promotes improved interaction between the Rose alloy and the copper coating of the board.

2. Place the water on low heat, approximately 1000 C (melting point of the Rose alloy). Then you need to throw several granules of this alloy into the water.

3. The etched board must be thrown into water and wait for a while. Then you need to turn it over with the tracks down using a stick/tweezers towards the molten alloy. Next, you need to move it along the bottom for a while and turn it over.

4. Before sticking the board out, you should wipe it using a piece of foam rubber or cotton wool.

Rose alloy soldering

It should be noted that the technological process of soldering to Rose is similar to soldering with other types of solders. A significant advantage of soldering with Rose alloy is that it does not require additional energy consumption. The fact is that the temperature required for melting is extremely low. It is even lower than the temperature at which water turns into steam. This ensures a reduction in the heating level of soldering equipment tips.

It must be emphasized that the Rose alloy is poorly suited for precision casting, being significantly inferior in quality to Wood micro-castings. However, due to the relatively low price of Rose's alloy, it can be considered an alternative to Wood's alloy: the cost of micro-castings rejected for quality and their subsequent remelting is comparable to the cost of using Wood's alloy in the production.

In general, Rose alloy is a worthy alternative to conductive materials and other solders.

At the same time, with the help of modern technologies, the production of products from this alloy can be ensured using both casting and low-temperature extrusion.

Using this alloy, you can save a lot on environmental fees due to the absence of cadmium, which is very aggressive and expensive to dispose of. Thus, purchasing Rose alloy as the main material is a completely logical decision.


How to use Rose solder

When producing printed circuit boards and assembling components, their surface must be prepared for upcoming soldering. In many situations, the solution to the problem is chemical tinning using Rose solder.

The composition is named after the chemist who proposed the solder recipe. A legend from not very ancient times says that Newton was the first to discover a melting point of a composite of three metals that was conveniently low for practitioners. Rose slightly modified the ratio and offered the composition to the broad masses of tinkers.

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What is

On the domestic market, Rose alloy is often offered under the abbreviated name POSV-50. The abbreviation for solder represents all the components: tin, lead, bismuth.

The number indicated after the letters informs about the percentage of bismuth. It is equal to half of the total mass. The other half contains equal parts lead and tin.

Tinning with Rose alloy has become widespread due to its melting point, which falls within the range of 94 to 98 ℃. The interval is due to the natural error when weighing the initial components during the production process.

Soldering with Rose alloy must be done with caution. Once solidified, the solder becomes very brittle.

The resulting junction of parts must not be subjected to any mechanical loads. This is fraught with the appearance of cracks invisible to the eye, which will bring all efforts down the drain.

How to prepare a solution for tinning

Tinning a board using POSV-50 is not difficult. Tinning can be done in water or a mixture of water and glycerin. Both liquids are always available.

The addition of glycerin is needed to completely melt the Rose solder. At 94℃ it just starts to melt. Water, as you know, at 100 ℃ will already begin to evaporate.

Therefore, for complete melting, a small temperature reserve is needed, which is created by adding glycerin. It mixes well with water and dissolves. The boiling point of the solution increases.

With a 1 to 1 ratio of glycerin and water, the boiling point of the solution will be 110 ℃. With a ratio of 2 to 1, the boiling point will be almost 104 ℃.

To improve the quality of Rose solder, you can add a little citric acid to the solution.

It is enough to add 1 g of powder to 100 ml of water. Many craftsmen add an approximate amount of citric acid. It will not harm the tinning.

The acidic component acts as a flux additive and eliminates the formation of oxides. Thanks to glycerin, the wettability of the working surface with Rose solder improves.

How to make at home

At home, hot tinning of a printed circuit board is very simple. The workplace will be a kitchen stove.

What do you need:

Tinning order:

  1. Place a bowl of water and glycerin on the burner.
  2. Pour a whisper of citric acid into it.
  3. Drop one tablet of Rose's alloy into the solution.
  4. Wait until it melts in the hot solution.
  5. Dip the board in there.
  6. Using a spatula, apply Rose's solder across the surface. You can turn the board over.
  7. Then place it on a piece of PCB.
  8. Use a spatula to scrape off the excess layer of Rose's solder.

After all the procedures, you can remove the board, wipe it with a cloth and enjoy the result. Some people like to wash it with soap. In our opinion, this is not necessary.

Please note that dishes for hot tinning should not be aluminum or cast iron.

It is best to take an enamel container, which then under no circumstances should be used for cooking. Work must be carried out with gloves.

Rose solder is popular not only as a means for tinning. It is used as a fusible fuse in fire alarms and electrical networks.


Wood's alloy

During soldering, difficult situations periodically arise when you need to get closer to the maximum manifestation of one of the parameters. When working with thin parts, for example, when repairing mobile phones and other microcircuits, high strength is not required, but the lowest possible melting point is needed.

Naturally, strength would not be superfluous, but such compounds are created using hard-melting metals and their alloys, so it is difficult to use them in this area. Wood's alloy solder is created precisely for such purposes in order to have a high density at a low melting point.

This is not the only area in which this material is used.

Appearance of Wood's alloy

It can also be found in precision casting and in the repair of pipes made from thin sheets of metal. Rods are made from it for subsequent melting of various shapes. With its help, various bodies are produced by electroforming. In addition, it is often used in chemical laboratories. In the technical field, Wood's alloy is used for tinning tracks that serve to conduct current in printed circuit boards.

Tinning chip with Wood's alloy

For ordinary soldering, where strength, temperature resistance and other mechanical parameters are needed, it is better not to use it, but for its field it has become a unique product that firmly occupies its niche. Wood's alloy is produced according to TU 6 09 4064 87.

Wood Alloy is supplied in the form of special granules. This may be a package containing 100 grams, or another weight, of a substance. This option is due to ease of use. The granules are gray-black in color. When touched by a soldering iron, they melt quite easily and stick to the tip. They are easy to store and do not require special transportation conditions.

Advantages of Wood's Alloy

  • One of the lowest melting temperatures, which is below one hundred degrees Celsius, which allows it to be used for temperature-sensitive parts, as well as the use of low-power tools;
  • An affordable alloy that is widely used;
  • Is indispensable for many areas;
  • Has high density.


  • It cannot withstand high temperature loads, due to which its scope of application is limited even in domestic conditions;
  • During operation, it turns out to be very sensitive to mechanical loads, so even small impacts can crack.

Wood's alloy composition

The uniqueness of this material lies in its composition. Here you need not only the exact presence of certain elements, but also the ratio of their content. The exact and most effective composition of Wood's alloy is as follows:

Chemical element Composition ratio, %
Bismuth 50
Lead 20
Cadmium 12,5
Tin 12,5

Specifications of Wood's alloy

The main property of the material is its fusibility under almost any conditions, as well as fairly good ductility. It can interact with almost any metal surface. The deposited metal has a fairly high density when compared with other solders with a low melting point. The exact characteristics of the material are as follows:

Parameter Units Meaning
Melting temperature Degrees Celsius 72
Density kg/m2 9720

Soldering Features


The melting point of solder is very low, which leads to many other features."

Wood's alloy is used in a narrow technical field and in chemical operations. But most often it is used as solder. Low temperatures suggest that you need to use weak soldering irons so that no overheating occurs and the composition retains its viscosity in the molten state, since this is the best state for soldering.

When working with small parts, you should use a thin, flat tip of the tool so as not to use too much consumables. Using a lot of solder will not necessarily make a good connection, as accuracy is more important here. Otherwise, it may turn out that the soldering area has blurred, and excess drops have landed on those parts of the circuit where they should not be. Then you will need to look for a way to remove solder from the board. Thus, it is better to immediately take minimal portions.

Despite the low melting point, Wood's alloy is preferably used with fluxes that are suitable for all low-melting materials. This will improve the quality of the connection and eliminate even the minimal risk of problems during soldering. But sometimes the material itself is used for tinning when working with high-temperature solders. Thanks to it, the adhesion of other materials improves, and a powerful soldering iron will quickly turn the alloy into a liquid state.

Movements must be as clear and fast as possible, since during use the material begins to quickly harden. After application to the surface, you should not subject it to rigorous checks, as there is a high risk of damaging the solidified solder, even if the connection is made well. Wood's alloy turns out to be quite fragile, so it is quite enough to carry out visual quality control and not expose the deposited metal to great dangers.


Domestic producers of this material predominate on the market:

  • Ural Chemical Reactants Plant;
  • analytical grade;
  • TinCom.


brief information

The composition of the Rose alloy includes:

  • bismuth 50%;
  • lead 25%;
  • tin 25%.

The permissible deviation of the proportions of the components is ±0.5%. In terms of physical parameters, this solder is close to Wood’s alloy, but has less toxic properties due to the absence of cadmium in its composition, therefore it is more suitable for home use. Its use does not require equipment with an exhaust hood at the workplace.

The melting point of the Rose alloy is +94 °C. It hardens already at +93 °C. This temperature regime is successfully used for tinning boards with Rose alloy. At home, this process can be carried out in boiling water. But it should be remembered that this alloy is sensitive to overheating, in addition, it is quite fragile.

Rose alloy, what is it and why is it called that? Solder is named after the famous German chemist Valentin Rose Sr. and consists of small silver-colored granules or rods.

Soldering with a similar composition facilitates the connection of temperature-critical contacts of radio components and elements in microelectronics due to the low melting point. It is used in industry as POSV-50 grade solder. This material is successfully used for soldering copper, its alloys with aluminum, nickel, brass, silver-plated surfaces of ceramic elements, and precious metals.

Technology of tinning circuit boards in boiling water

Due to the unique temperature characteristics at home, the following technology for tinning printed circuit boards using Rose alloy has been developed. What is it and how does it work?

The first step is to clean the etched copper surface of the PCB.

Then heat a small enameled metal container (bowl or pan) filled with water to boiling temperature. A large tin can will also work. Throw a small amount of citric acid into boiling water.

After this, carefully lower the printed circuit board to the bottom of the container with the tinning surface facing up. The required amount of Rose's alloy granules is lowered after her. After this, in boiling water, the molten granules are distributed evenly with a wooden stick or rubber spatula over the copper surface of the board. In this case, the tinning process occurs.

Excess solder is removed with a swab or spatula. After this, the tinned board is removed from the container and allowed to cool. The result is a bright, almost mirror-like tinned surface, not inferior in quality to an industrial sample.

In order for subsequent soldering with Rose alloy to have sufficient strength and not be brittle, it is necessary to achieve a minimum thickness of the tinning layer. Afterwards, you must thoroughly rinse the surface of the board with water to remove any remaining acid. To further reduce oxidation, it is advisable to cover it with a layer of an alcoholic rosin solution. It will prevent access of oxygen to the metal surface and during the soldering process will act as a flux, ensuring impeccable joint quality.

Techniques for working with glycerin

There is a method of tinning in glycerin with Rose alloy. What is it and how to organize the process? For tinning, it is advisable to use an enameled metal container, say a bowl. It is half filled with glycerin from the nearest pharmacy and heated to a temperature of about 200 ° C. You need to add a few drops of soldering acid to the liquid.

Next, the board is lowered into heated glycerin with the stripped copper layer facing up. Rose alloy granules are thrown from above. Then, using a rubber spatula, the molten metal balls are rubbed over the copper surface of the board. After which the workpiece is carefully removed with tweezers and thoroughly washed with running water to remove acid and glycerin.

The shiny tinned surface is covered with a layer of alcoholic rosin solution. After this, the board is ready for use.

Simplified tinning technology

If there is no desire to tinker with metal containers, boiling and acid, a radio amateur can tin a printed circuit board in the simplest way. Tinning in this case is also carried out with Rose alloy.

What is it and how is it done? The copper foil of the printed circuit board is cleaned with sandpaper and coated with an alcohol solution of rosin, the so-called liquid flux.

After this, you need to put the required amount of Rose alloy granules on the copper tracks of the board and use a low-power soldering iron to carry out the tinning process through the fluffy braid of the coaxial cable. Then wash off the remaining flux with alcohol and cover it with an alcohol solution of rosin as a kind of protective varnish.

Advantages and disadvantages of tinning technologies

Each of these methods has its positive and negative sides. Tinning in boiling water is preferable due to the low operating temperature (up to +100 °C). It gives a high quality tinned surface and does not damage thin circuit board traces or etched inscriptions.

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When working in glycerin heated to 200 °C, a similar coating quality is obtained. But there is a danger of getting burned by the oily heated liquid. Glycerin vapor also does not improve the health of the radio amateur. In addition, it should be remembered that when dehydrated glycerin is overheated, the substance acrolein appears, which belongs to class 1 harmful effects and has strong carcinogenic properties.

Tinning with a soldering iron is easier and faster, but there is a danger of overheating with peeling of foil tracks and etched inscriptions on the printed circuit board.

Making Rose alloy with your own hands

It is not always possible to purchase the necessary materials. In this case, you should try making them yourself. To obtain the alloy, you must first purchase bismuth. Instead of pure tin, you will have to use tin-lead solder, since pure metal is not always available. Regular solder contains approximately 40% lead and 60% tin. You need to take a piece of solder and a piece of bismuth of exactly the same volume.

Mix all components in a crucible and melt with the addition of rosin flux. Then carefully pour the molten solder in a thin stream into a container of water. Rose alloy granules will form at its bottom. Of course, this method is not entirely accurate, so the percentage of metals will not fully correspond to the norm, as will the melting point. To more accurately obtain the alloy, Rose will need chemically pure tin, lead and bismuth.

Safety and Precautions

Although Rose's alloy does not contain cadmium, its components (lead and bismuth) can cause an allergic reaction or intoxication. Therefore, it is better to keep the alloy in a tightly sealed package. The shelf life of the composition is about 3 years.

When soldering and tinning, safety precautions must be observed. Work in a ventilated area. Avoid inhaling lead, tin and bismuth fumes. Vapors from rosin and glycerin are also harmful.

When working with a heated crucible, protective equipment in the form of thick gloves and glasses is required.


Soldering and tinning with Rose alloy

Category: Soldering 08.25.2019 · : 0 · Reading time: 4 min · Views:

Rose alloy is a low-melting material with a melting point of about +94 °C. Composition: tin, lead and bismuth. Used for low-temperature soldering and in some fuses. Stored in small granules.

Properties and Application

Well suited for desoldering parts, connectors, cables of SMD microcircuits and dismantling protective metal screens from mobile phone boards.


  • Low melting point. Soldering connectors and parts without overheating.
  • Fragility . Soldered connections are unreliable. Because of this, it is better not to solder them, but only desolder the board components.
  • Toxicity. Soldering work only in a ventilated area.

Alloy of Wood and Rose

Another popular material is Wood's alloy.

Melting point is about 68 °C. Externally it differs in the smaller size of the granules. The composition is similar, but it also contains cadmium. Because of the latter in its composition, it is very toxic.

Soldering with this type of solder is not recommended under any circumstances!

Only as a last resort and in a ventilated room. Do not overuse this alloy. If there is a choice between Rose and Wood, it is better to use the first and avoid the second.

Soldering methods

To desolder a connector or part from a board without overheating, you need to tin the contacts with a low-melting material.

The final melting point will be higher than that of Rose in its pure form, since it is mixed with solder on the board, which has a different composition and characteristics. (melting at 270 °C)

The location of work is important. For example, a board can be very heat-intensive due to its thickness. The heating time and power should be longer than that of a lighter board.

The motherboard from a computer will have to warm up longer than a small motherboard from a mobile phone due to the greater multi-layering and thickness of the PCB.

First, flux is applied to the contacts of the part to be soldered. A few granules of low-melting solder are added. There are several soldering techniques.

Working with a soldering iron

You need massive stings: mini wave, hatchet.

The soldering iron temperature can be kept within 230°C, for example 200°C.

The contacts of the part must be tinned with a low-melting alloy, after applying flux.

A drop of solder forms on the contacts, which can be easily heated with one soldering iron at low power.

The result of soldering work.

How to desolder a USB connector with one soldering iron and Rose

Fast and safe soldering with one soldering iron and low-melting solder.

Soldering with a hairdryer

The hairdryer is set to a temperature of approximately 120 - 170 °C with medium air flow.

The granules gradually melt and mix with the contacts. It is better to adjust them with tweezers at the soldering site so that the solder is better distributed.

It is necessary to thoroughly warm up the soldering area. Gradually, as the temperature rises, the part will begin to desolder. This will be noticeable when a glare appears on the solder.

Result of low temperature soldering.

Combined method

A hairdryer on top of the soldering area is needed for an auxiliary tool, at 100°C, and a soldering iron is used to solder parts with Rose alloy at a temperature of 200°C.

After soldering the part, it is necessary to clean the resulting solder mixture using braid.

Is it possible to solder and tin with rose?

The alloy is suitable for desoldering parts from a board, but in no case for final soldering of parts onto a board because of its fragility. Rose alloy is very fragile, the connections are unreliable. This is especially true for connectors and wires. When electrical current flows through the board or wires, heat is generated.

Because of this, the low-temperature alloy begins to melt. In addition, it does not tolerate vibration or mechanical shock. Microcracks appear, oxides occur and loss of connection occurs.

Tinning with Rose alloy

Radio amateurs have a popular “lazy” way of tinning boards using Slava Rose. To do this, several granules of low-temperature alloy and boards that need to be tinned are added to a boiling pan with a pinch of citric acid. The solder is distributed evenly in a matter of seconds. The main disadvantages of this tinning method are the toxicity and the same fragility of the alloy.

A significant drawback is fragility and toxicity. It is because of this that you should not solder parts with such an alloy.

Precautionary measures

Since the materials used are toxic, it is imperative to solder in a ventilated area and use protective equipment.

During soldering work, you need to keep your distance and wear safety glasses. Molten drops of metal can get on the skin or mucous membranes, thereby causing burns and infection.

Take the granules themselves only with tweezers, avoiding contact. They are not that toxic, but it greatly reduces its impact.

The alloy and its particles should not be allowed to come into contact with open wounds.


Rose alloy copes with low-temperature desoldering of parts from boards. It can only be used for these purposes. Tinning boards is not a good idea due to unsatisfactory strength characteristics and resistance to mechanical damage or vibration.

If you choose between Rose and Wood, the first one wins. There is not much difference in temperature between them. This is not such an important parameter that you would sacrifice your health for a lower soldering temperature.


Alloy Rose

If you take tin, lead and bismuth in proportions 1:1:2 and get an alloy, then it is called Rose’s alloy, or more precisely Valentin Rose the Elder, a German pharmacist and part-time chemist. Note that if the melting temperature (i.e., the transition from a solid crystalline state to a liquid) for tin is 231.9 degrees Celsius, then for the Rose alloy it will be about 94-98 degrees Celsius.

It would be fair to note that the championship in the discovery of the composition of elements for a low-melting alloy belongs to Sir I. Newton, who in 1701 recommended the proportion of these elements 2: 3: 5. Valentin Rose dared to deviate from this recommendation 45 years after the departure of the one who “in intelligence surpassed the human race.”

Rose's alloy is often confused with Wood's alloy, as they are similar in appearance. But Wood’s alloy, on the one hand, has a lower melting point (68.5 degrees Celsius), and on the other hand, this is due to the cadmium added to the composition, which is a toxic and carcinogenic element, which can only be worked with with all precautions. It is precisely because of the toxicity of cadmium in Wood's alloy that Rose's alloy has become more widespread.

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It contains tin, lead and bismuth. Used for low-temperature soldering, used in some fuses. Stored in small granules. This type of slava is well suited for soldering parts, connectors, cables and SMD microcircuits. Excellent for removing protective metal shields from mobile phone circuit boards.

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WATCH THE VIDEO ON THE TOPIC: Alloy Rose. Soldering, tinning, composition, application and melting point.

Bismuth (Bi), a metal from China. A little home alchemy, or how to prepare a Rose alloy in the kitchen

Login or email Enter or register. Authorization Login or email I got tired of tinning boards with a soldering iron, and I remembered that somewhere they wrote about the possibility of tinning Rose alloys in heated glycerin. Now there is no soldering tin: If only I had Wood’s alloy, I could tin it in boiling water.

Alloy ROSE 1pc (g) buy retail and wholesale with delivery.

Alloy ROSE 1pc (100g)

Rose's alloy is similar to Wood's alloy, but differs from it in less toxicity, since it does not contain cadmium. It is used in electrical fuses. Used in radio engineering as solder POSV Wikimedia Foundation. Rose alloy; Rose metal rus. Wood's alloy is a heavy fusible alloy invented in the year R. Rose, Valentine the Elder - Wikipedia has articles about other people with this surname, see Rose V.

Alloy Rose

Rose alloy for semiconductor technology, for soldering aluminum, aluminum with copper and its alloys in field connections, for soldering and tinning of copper, nickel, brass, bronze, copper and copper-nickel alloys with silver-plated ceramics, soldering of silver-plated parts, for soldering and tinning jewelry. Rose's alloy is similar to Wood's alloy, but differs from it in less toxicity, since it does not contain cadmium. When you subscribe to our mailing list, we PROPERLY add your email address to the appropriate mailing list. While it is stored there, we know that we will be able to contact you if necessary.

In the comments, the topic of using Rose alloy for soldering elements has been raised several times lately, and this article on this topic was just published on Habré. A long, long time ago, when I was a schoolboy and was extracting radio components mainly from various boards thrown into a landfill, I noticed an unusual phenomenon in the process of soldering another such board: some solders instantly fell off the foil as soon as I poked them with a soldering iron.

Application of Rose alloy

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Rose's alloy is an alloy of low-melting metals. It was obtained by the German chemist Valentin Rose the Elder. The melting point of the alloy is +94°C, .

Rose alloy: what is it, composition, application

VIDEO ON THE TOPIC: What is Rose Alloy, its properties, and where I use it

This alloy is used for soldering aluminum, nickel, brass, bronze, silver-plated jewelry parts and parts characterized by increased sensitivity to overheating.

Rose alloy, which is a POSV solder, has found its application in semiconductor technology, radio engineering and electrical fuses. The developer of the alloy is considered to be Valentin Rose the Elder, a German pharmacist and chemist. Rose alloy can be transported both by road and by rail.

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Storage can be carried out not only in closed warehouses, but also in open space in hermetically sealed packaging.

A manufacturer whose area of ​​interest includes the production of low-melting conductive elements can only benefit from the use of alloys. Rose instead of Wood, saving on disposal costs and environmental damages.

Rose alloy + glycerin

The history of the discovery of Rose's alloy is closely connected with Isaac Newton. It was he who laid down the main series of elements of this low-melting compound in 2009. The alloy proposed by Newton had several disadvantages.

In particular, it had an increased tendency to crack. No one dared to challenge this combination of elements due to the great authority of the scientist.

After etching and clearing the printed circuit board of toner, it must be removed. This must be done in order to prevent the copper of the tracks from oxidizing. It is impossible to solder anything normally onto oxidized tracks - the solder will not stick.



Radio electronics for beginners

At the beginning of their amateur radio activities, many novice radio amateurs rarely ask themselves about the types of solders and what their properties are.

To assemble the simplest homemade devices, the most common POS-61 or similar is sufficient. As they say: “It would be something to solder with”

You don't even have to buy solder. It is enough to take an old printed circuit board from some electronic device and assemble it with a heated soldering iron tip from the soldered contacts.

This method of “extraction” is especially relevant for those who live far from cities and large populated areas, where there is no opportunity to visit a radio store.

Solder collected from printed circuit boards

But still, solder to solder is different. In his practice, a person dealing with electronics must understand the issue of his choice. Therefore, we will consider in detail what types of solders there are, what they are used for, which one is better to use for installing electronic circuits and repairing household radio equipment.

What types of solders are there?

Solders are divided into soft (low-melting) and hard. For the installation of radio equipment, low-melting ones are used, i.e. those whose melting temperature ranges from 300 to 4500C. Soft solders are inferior in strength to hard solders, but they are used for assembling electronic devices.

Solder is an alloy of metals. For low-melting solders, this is usually an alloy of tin and lead. It is these metals that make up the majority of the alloy. Alloying metals may also be present in it, but their quantity in the composition is small. Impurities of other metals are introduced into the alloy to obtain certain characteristics (melting point, ductility, strength, corrosion resistance).

The most widely used type of solder is POS (Tin-Lead Solder). Next, a brief designation of its brand is followed by a number that shows the percentage of tin in it. So POS-40 contains 40% tin, and POS-60, respectively, 60%.

It happens that solder of an unknown brand comes into use. Its composition can be roughly assessed by indirect signs:

  • Solders of the tin-lead group have a melting point of 183 – 2650C.
  • If the solder has a bright metallic sheen, then it has a fairly high tin content (POS-61, POS-90). And, conversely, if it is dark gray in color and the surface is matte, then this indicates a high lead content. It is lead that gives the surface a peculiar grayish tint.
  • Solders containing a lot of lead are very ductile. For example, a solder rod with a diameter of 8 mm. with a high lead content (POS-30, POS-40) is easily bent by hand. Tin, unlike lead, gives the alloy strength and rigidity. If there is a lot of tin in the alloy, then it will no longer be possible to bend such a rod easily.

POS-40 (bar)

Let's consider the purposes for which solders of the tin-lead group (POS) are used.

  • POS-90 (Sn 90%, Pb 10%). Used for repairing food utensils and medical equipment. As you can see, it contains a small lead content (10%), which is quite toxic and its use in things that come into contact with food and water is unacceptable.
  • POS-40 (Sn 40%, Pb 60%). Mainly used for soldering electrical equipment and parts made of galvanized iron, used for repairing radiators, brass and copper pipelines.
  • POS-30 (Sn 30%, Pb 70%). It is used in the cable industry, and is also used for tinning and soldering zinc sheets.
  • And finally, POS-61 (Sn 61%, Pb 39%). Same as POS-60. I don't think there's much difference between them.

POS-61 is used for tinning and soldering printed circuit boards of radio equipment. It is mainly used as a material for assembling electronics. Its melting point starts at 1830C, and complete melting is achieved at a temperature of 1900C.

Soldering with such solder can be done using a conventional soldering tool without fear of overheating of the radioelements, since its complete melting is achieved already at 1900C.

POS-30, POS-40, POS-90 completely melt at temperatures of 220 – 2650C. For many radio-electronic components, this temperature is subcritical. Therefore, it is better to use POS-61 for assembling homemade electronic devices.

A foreign analogue of POS-61 can be considered Sn63Pb37 (63% tin, 37% lead). It is also used for soldering radio equipment and for making homemade electronics. Radio amateurs choose it as an alternative to the domestic POS-61.

As a rule, any solder is sold in coils or tubes of 10 ~ 100 grams. The composition of the alloy is indicated on the packaging, for example, like this: Alloy 60/40 (“Alloy 60/40” - also known as POS-60). It has the shape of a wire of different diameters (from 0.25 to 3 mm).

It is also not uncommon that it contains flux (FLUX), which fills the core of the wire. flux is indicated as a percentage (usually from 1 to 3.5%). This form factor is very convenient. During operation, there is no need to separately supply flux to the soldering area.

One of the varieties of POS solders is POSSu . Yes, if you say it out loud, it doesn’t sound very presentable.

But, despite this, tin-lead solder with antimony (this is how the abbreviated designation stands for) is used in the automotive industry, in refrigeration equipment, for soldering the windings of electrical machines, elements of electrical equipment, winding parts and cable products. Well suited for soldering galvanized parts. In such an alloy, in addition to lead and tin, there is from 0.5% to 2% antimony.

Solder Initial melting t0 (Solidus) Full meltdown (Liquidus), t0
POSSu-61-0.5 183 189
POSSu-40-2 185 229
POSSu-40-0.5 183 235
POSSu-30-2 185 250
POSSu-30-0.5 183 255

As we can see from the table, POSSu-61-0.5 solder is most suitable for replacing POS-61, since it has a complete melting temperature of 1890C.

It is worth noting that there is also a completely lead-free tin-antimony solder POSu 95-5 (Sn 95%, Sb 5%). Its melting point is 234 – 2400C.

Low temperature solders

Among the solders, there are also those that are designed specifically for soldering components that are very sensitive to overheating. The most “high-temperature” among low-temperature ones is POSK-50-18 . It has a melting point of 142–1450C. POSK-50-18 contains 50% tin and 18% cadmium. The remaining 32% is lead. The presence of cadmium in the alloy increases corrosion resistance, but also makes it toxic.

Next in decreasing melting temperature is the ROSE alloy (Sn 25%, Pb 25%, Bi 50%). Marked as POSV-50 . Its melting point is lower than the boiling point of water and is 90 – 940C. It is designed for soldering copper and brass. In the composition of the ROSE alloy, tin occupies 25%, lead – 25%, bismuth – 50%. The percentage of metals in the alloy may vary slightly. Usually indicated in the “Composition” column on the packaging.

This alloy is very popular among radio mechanics and, in general, among all electronics engineers. It is used for dismantling/installing elements sensitive to overheating. Among other things, this alloy is ideal for tinning copper tracks of a newly manufactured printed circuit board.

Finds application in protective fuses that can be found in any radio equipment.

An even lower temperature alloy is WOOD (Sn 10%, Pb 40%, Bi 40%, Cd 10%). Its melting point is 65 – 720C. Since the WOOD alloy contains cadmium (10%), it is toxic, unlike the ROSE alloy.

It is worth noting that ROSE and WOOD alloys are quite expensive.

Solder paste



Rose's alloy is a chemical compound of bismuth (50%), tin (25%) and lead (25%). Externally, the alloy is similar to silver. The melting point is just below the boiling point of water and is 94 degrees.

Bismuth itself, which is the base component in this alloy, does not have high ductility properties. For this reason, it is rarely used in its pure form when soldering various types of metals. However, the Rose alloy obtained on its basis is excellent for the manufacture of low-melting solder POSV-50.

This solder tends to increase in volume as the liquid phase transitions to the solid phase. Also, a similar process occurs in alloys during cooling after crystallization.

POSV-50 solder made from Rose alloy does not wet materials such as structural steel and other iron-based compounds poorly, has rather low mechanical characteristics and reduced electrical conductivity. To increase soldering efficiency, steel alloys are pre-tinned with tin-lead solders and galvanized. As a result of such actions, the wettability of the surface improves and, accordingly, the adhesion of the alloys to each other.

Improving the wettability of the Rose alloy with copper is facilitated by alloying its composition with metals such as palladium, platinum, cobalt, nickel and iridium. The amount of these elements ranges from 0.5 to 2%.

The effect of increasing volume from the transition between phases is significantly enhanced after the introduction of germanium, silicon and gallium into the alloy. Increasing the germanium content in the alloy, among other things, has a positive effect on its strength characteristics.

The tensile strength of a copper joint soldered with POSV-50 solder is 14.5 MPa. This is a rather low value, considering that the same indicator for most solders is at the level of 20-22 MPa. For this reason, Rose alloy solder joints are not recommended for use in shock load environments, as there is a high probability of cracks forming.


In terms of appearance and quality characteristics, Rose's alloy is very similar to Wood's alloy. The difference between them is that the Rose alloy does not contain cadmium particles and this makes it less toxic. This parameter helps the alloy find wider application among radio amateurs working at home: the soldering process does not require special exhaust equipment to remove poisonous gas from the room.

POSV-50 solders based on Rose material are used for soldering contact elements with an increased tendency to overheat. It is also increasingly used as a solder for various aluminum and copper alloys.

Rose's alloy serves as a solder for semiconductors. It is used to produce aluminum fuses. In addition to the above, the alloy is used as a solder for nickel contacts and jewelry.

Rose is also used in tinning. The alloy achieved its greatest popularity when tinning copper surfaces of microboards. This process is as follows:

  • Boil a container of water. It is worth noting that the most suitable containers are made of cast iron and aluminum, or enameled. Galvanized and copper utensils will dissolve when tinning, which leads to a deterioration in the quality of the solder and, accordingly, the impossibility of its reuse. Also, in the future, this container cannot be used for cooking, because During tinning, a thin layer of lead is deposited on the surface of the cookware.
  • Add a few grams of Rose alloy, citric acid and glycerin. Glycerin is necessary to obtain the required melting point and reduce the emission of harmful gases from the alloy. The presence of citric acid turns the water-glycerin solution into a flux, which prevents its contamination by gases such as oxygen, hydrogen and others.
  • Place the board copper side down. Note that the board must be cleared prematurely. This is done in order to preserve the solder from contamination and increase its service life.
  • After 15-20 minutes, the board is removed and cleaned of copper residues.

Tinning with Rose alloy has achieved wider application compared to soldering. The simplicity of the process and the availability of the necessary components play an important role here.


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