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DIY solder for aluminum. Soldering aluminum at home is a simple and safe activity. Brazing of aluminum alloys

People learned to solder metal products back in ancient times, as soon as they learned to smelt tin and lead. Of course, the most in a simple way fastenings metal products between themselves is the use of an ordinary bolt with a nut, because this does not require their preliminary preparation, the use of various solders, fluxes, etc. However, metal soldering is widely used in both industrial scale, and in everyday life.

Before you start soldering, the surface of the parts to be joined is cleaned with sandpaper or a file and lubricated with flux. The heated soldering iron is immersed in ammonia or rosin to clean it of metal oxides, after which the molten solder is transferred to the soldering site.

As for aluminum or its alloys, rapid oxidation of the soldered surface occurs here, and conventional soldering methods do not give the expected result. The fact is that the surface of aluminum products is covered on top with a very thin, elastic, but at the same time quite durable film of aluminum oxide. After removing it mechanically, the newly cleaned surface from contact with air is instantly covered with an oxide film. Despite this, soldering aluminum at home is possible. If soldering is performed using tin-lead solders, you can use the following method.

Liquid mineral oil is applied to the place of the upcoming soldering, and already under the oil layer the surface is cleaned with a knife blade or scraper to remove the oxide film. After this, you need to apply solder with a very heated soldering iron. Usually a 50 W soldering iron is sufficient for this. For aluminum products with a thickness of more than 1 mm, it is better to use a tool of greater power.

Instead of mineral oil, you can use sewing machine oil or Vaseline oil, but gun oil is best suited for this purpose. The solder used must contain at least 50% tin. A good result is achieved by using low-melting solder POS-61. If you are soldering aluminum with a thickness of 2 mm or more, the surface must be thoroughly heated with a soldering iron before applying oil to the soldering area.

You can also apply rosin mixed with fine iron filings to the seam. A tinned file is used to wipe the seam area with added solder. Sawdust plays the role of an abrasive material, removing the oxide film from the surface of the product with sharp edges. As a result, tin adheres firmly to the surface, and aluminum is soldered more reliably.

In order for the work to be especially effective, the soldering iron should be slightly modernized. To do this, the working part of the copper rod is blunted so that a platform 4-5 mm wide is formed on it, after which a small longitudinal cut (7-8 mm) must be made with a hacksaw. From hacksaw blade, previously calcined over fire, you need to cut out a small piece (1-2 mm), treat it to remove scale with a 20% mixture of sulfuric or hydrochloric acid, place it in the cut and compress it tightly in a vice. Such a tip will more effectively remove the oxide film from the surface, and the aluminum will be better seized by solder.

In industrial conditions, soldering of aluminum and its alloys is also performed with a conventional soldering iron using a flux consisting of a mixture of oleic acid and lithium iodide.

The procedure for soldering aluminum elements at home is a very problematic process, which is facilitated by the use of special materials. The work is complicated by the immediate appearance of a thin oxide film at the stripping site, which interferes with soldering. An additional difficulty is created by the material itself, which has a low melting point (+660 °C). Using solder for soldering aluminum, special strong fluxes and following technology, you can independently solder almost any aluminum object.

Features and principles of soldering

The low temperature value of metal melting makes it difficult technological process soldering, as well as repairing products with your own hands. Parts very quickly lose strength when heated, and structures reduce stability when the temperature reaches 300 degrees. Low-melting solders consisting of bismuth, cadmium, indium, and tin come into difficult contact with aluminum and do not provide sufficient strength. Excellent solubility is observed in the metal in combination with zinc, which makes the soldered areas highly reliable.

Before soldering begins, aluminum elements are well cleaned of oxides and dirt. To do this, you can use mechanical force with brushes or use special fluxes made from a potent composition. Before the procedure itself, be sure to tin the areas to be treated. The tin coating will protect the part from the formation of oxides. In order to reliably solder aluminum products, it is necessary to choose the right heating tool, taking into account the volume of metal being processed. In addition, the reliability of the connection depends on the alloy chosen, as well as the flux for soldering aluminum.

Soldering methods

Soldering of aluminum products is done with a soldering iron electric type, blowtorch or gas torch. There are three ways to solder various aluminum objects:

with rosin;
using solders;
electrochemical method.

With rosin

This option for soldering aluminum objects, wires, cables is used for parts small size. To do this, the cleaned section of the electrical wire is covered with rosin and placed on a piece of sandpaper with a medium grain size. The wire is pressed from above with the tinned tip of a heated soldering iron. This action is carried out several times, after which the procedure of soldering the electrical wires itself is performed. You can use a rosin solution in diethyl ether.

In this case, the end of the soldering iron is not removed from the end being tinned, but rosin is added on top. For twisting thin aluminum wires An electric soldering iron with a power of about 50 W is suitable. With an aluminum thickness of about 1 mm, a 100 W soldering iron is required, and parts larger than 2 mm require preheating of the joint.

Using solders

This method is the most common and is used in electrical engineering, in the repair of automobile parts, as well as other products. Before soldering aluminum, the area to be soldered is pre-coated with an alloy and the tin-plated elements are subsequently connected. Pre-tinned parts are connected to each other, as well as to other alloys and metals.

Soldering of elements can be carried out using light-alloy solders containing tin, zinc, and cadmium. In addition, refractory materials based on aluminum are actively used. Why are light alloy compounds used? Because they allow you to solder an aluminum product at temperatures up to 400 degrees. This does not produce qualitative changes in the properties of the metal and maintains its strength. Compositions with cadmium and tin do not create sufficient contact reliability and are susceptible to corrosive effects. Refractory materials containing zinc, copper, and aluminum-based silicon do not have these disadvantages.

Electrochemical method

This procedure requires a plating facility. With its help, copper plating is carried out on the surface of a product or wire. In its absence, independent processing of the part is used. To do this, apply a few drops of a saturated solution to the area cleaned with sandpaper. copper sulfate. After this, the negative pole of an independent power supply is connected to the workpiece.

They can be a battery, an accumulator, or any electrical rectifier. A cleaned copper wire with a diameter of about 1 mm, located in an insulated stand, is connected to the positive terminal. During the electrolysis process, copper will gradually deposit on the part, after which the area is tinning and dried using an electric soldering iron. After this, you can easily solder the tinned area.

Solders, materials, fluxes

Soldering of aluminum with tin is carried out subject to the use of highly active fluxes, as well as good cleaning of parts of the parts. Such tin compounds require additional coating with special compounds, since they have low strength and poor protection against corrosion processes.

How to solder aluminum elements? High-quality solder joints are obtained by using solders with silicon, aluminum, zinc, and copper. These materials are produced by both domestic and many foreign manufacturers. Domestic brands of rods are represented by the most used solders TsOP40, which according to GOST contain 60% tin and 40% zinc, as well as 34A (aluminum - 66%, silicon - 6%, copper - 28%). The zinc used gives high strength to the contact area and provides good corrosion resistance. Imported low-temperature alloys with excellent characteristics include HTS-2000, which provides maximum ease of use.

These alloys are used to work with large parts (radiators, pipes) with high heat dissipation using a heating pad or objects made of aluminum alloys, having a fairly high melting temperature. Novice repairmen can familiarize themselves with the soldering process by watching an instructional video. This will help to avoid many unpleasant nuances during the work process.

In addition to solders, aluminum soldering requires the use of special fluxes containing ammonium fluoroborate, zinc fluoroborate, as well as triethanolamine and other elements. The most popular is the domestic F64, which has increased chemical activity. It can be used even without first removing the oxide film from products. In addition to it, 34A is used, containing lithium, potassium and zinc chlorides, as well as sodium fluoride.

Preparation of products

Reliability, as well as excellent quality of connections, is ensured not only by the use of the right technology, but also from preparatory work. These include the treatment of sealed surfaces. It is necessary to remove contaminants and thin oxide films.

Mechanical processing is carried out using sandpaper, a metal brush, stainless steel mesh or grinder. In addition, various acid solutions are used for cleaning.

Surface degreasing is carried out using solvents, as well as gasoline or acetone. On the cleaned aluminum area, an oxide film appears almost immediately, but its thickness is significantly lower than the original one, which facilitates the soldering process.

Heating tools

How to solder aluminum at home? Electric soldering irons are used to solder small-sized aluminum products at home. They are a universal tool, quite convenient for soldering wires, repairing small tubes and other elements. They require a minimum of working space, as well as the presence of an electrical network. Repair of large-sized products and welding are performed with a gas torch that uses argon, butane, and propane. To solder aluminum objects at home, you can use a standard blowtorch.

Using gas burners it is necessary to constantly monitor their flame, which characterizes a balanced supply of oxygen and gases. With the correct gas mixture, the fiery tongue has a bright blue color. A dim hue, as well as a small flame, indicate an excess of oxygen.

Technological process

The technology for soldering aluminum objects is similar to the process of joining parts of other metal materials. The first step is to clean and degrease the areas of future adhesion. Then the connected elements are installed in working position for ease of processing. Flux is applied to the prepared area, and the initially cold product begins to heat up using an electric soldering iron or a torch. As the temperature rises, the solder bar begins to melt, which must constantly touch the surface of the elements, controlling the heating process. Soldering aluminum elements at home with an electric soldering iron is done in a well-ventilated room, as hazardous compounds are released during operation.

Using flux-free solder requires compliance with some nuances. To prevent the oxide film from interfering with the alloy getting onto the parts, the end of the rod makes scratching movements along the area where the elements are soldered. This breaks the oxide integrity and the solder comes into contact with the metal being processed.

Destruction of the oxide layer during soldering can be done using another method. To do this, the area to be treated is scratched with a metal brush or a stainless steel rod.

To ensure maximum strength of aluminum parts in the soldered area, the treated areas are pre-tinned. Compliance with the technology of soldering aluminum elements guarantees excellent quality of the connection, as well as its protection against corrosion.

Aluminum and its alloys are only slightly inferior in strength to steel, but are very easy to process and have a decent appearance and have such excellent qualities as thermal conductivity and electrical conductivity. However, along with these properties there is the difficulty of soldering them. The question of how to solder aluminum is asked not only by novice amateurs, but also by those who do not have difficulty soldering copper, brass and steel.

Soldering aluminum is a complex process, so you need to know all its technology.

Working with aluminum is not easy because of its ability to instantly oxidize in air, as a result of which the surface is covered with a thin film of Al2O3 oxide, which has increased resistance to aggressive environments.

Therefore, special mercury fluxes or replacement tips for soldering irons are used, or, depending on the soldering method, the oxide is removed in various ways. Before soldering aluminum, they resort to mechanical removal of the film, stripping a file, but contact of aluminum with water or air leads to the original state - the appearance of the same film.

For soldering aluminum, you can use a special flux.

Experts advise cleaning the soldering area with a brick or sand, without removing the dust, but applying molten rosin directly to it, then rubbing it with a soldering iron, pressing firmly with the tip. This will help break down the thin film that formed before applying the rosin.

Also, the stripped aluminum is filled with rosin and sprinkled with filings from an iron nail obtained during the filing process. Next, you need to tin the surface with a soldering iron, carefully rubbing it with the tip. Iron chips will destroy the film, while rosin will prevent the formation of a new film.

Chemical stripping methods

It is important not to allow the aluminum being stripped to come into contact with air; for this purpose, the soldering area is filled with flux or rosin, while heating it. Often small elements, such as wires, are dropped directly into rosin or flux poured into a container.

In addition to the mechanical method of removing oxide, there are several so-called chemical methods.

Cleaning aluminum before soldering can be done using copper sulfate.

Cleaning with copper sulfate. The point where solder needs to be made is cleaned with a file and moistened with two or three drops of copper sulfate solution. The aluminum base is connected to the negative pole of the battery or accumulator; a small piece of copper wire, stripped and connected to the positive pole, is lowered into the solution without touching the base. After turning on the 4.5 volt battery, a copper coating forms on the aluminum after a short period of time. The desired part is then soldered to the dried copper.

Use of abrasive powder. A liquid paste is prepared by mixing powder and transformer oil, which is applied to the cleaned surface and then rubbed in with a soldering iron until a layer of tin appears.

Another method is transformer. The product is connected to its negative side, a copper wire containing several cores is connected to its positive side. After closing the circuit, microwelding of aluminum and copper will occur. To speed up the process, soldering acid is used.

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Application of fluxes and solders

For soldering large parts, such as cooling radiators, soldering irons with high power (100-200 W) are used; soldering irons with a power of 60-100 W can handle small elements quite successfully. Of course, the solder area is not particularly strong, but this is not required.

At home, fluxes F-64, FTBf-A, and FIM are suitable for soldering aluminum. Of course, you can use aspirin, technical petroleum jelly, grease, solder fat, and stearin as a flux.

Using special active fluxes makes soldering easier; they cope well with the oxide film, provided that the heating temperature is 250-360°C.

The solder is distributed over the entire joint surface, resulting in a strong connection between the parts. Flux must be removed using solvents, alcohol or a special liquid. The convenience of using such fluxes is that they are also used for soldering nickel, copper and steel.

As a rule, alloys of 2 parts zinc and 8 parts tin, or 1 part copper and 99 parts tin, or 1 part bismuth and 30 parts tin are used for soldering aluminum. Conventional solders PIC. 40 and POS. 60 also copes with the task.

Small holes (no more than 7 mm in diameter) in aluminum cookware can be soldered without a soldering iron. The existing enamel around the hole should be beaten 5 mm by lightly tapping with a hammer. Now you need to use a file or sandpaper to clean the metal until it shines, using rosin crumbs or soldering acid, put a piece of tin in the pan on the hole and heat it over an alcohol lamp, which provides spot heating without destroying the remaining enamel. The metal, melting, will completely close the hole.

So, if you have the desire, you can solder aluminum at home.

Seal

Flux for soldering aluminum

Once upon a time, I thought that aluminum soldering was done in factories and was not done at home. However, over time, this misconception has dissipated. This article is about how to solder aluminum at home and what to use to solder aluminum.

At school, the topic of aluminum was previously discussed in chemistry and physics lessons about its properties; it has excellent electrical conductivity and thermal conductivity, but is very difficult to solder. The difficulty of soldering it is due to the fact that an oxide film instantly forms on the cleaned surface, which is very resistant to various aggressive environments.

Once upon a time I came across such information that soldering is carried out with a solder consisting of tin and zinc or tin and bismuth. However, practice shows that it can be soldered quite normally with conventional POS 40 and POS 60 solders. It doesn’t matter what you solder with, the main thing is how.

The mechanical strength of such soldering is small, but what is mainly required is not the strength, but the electrical conductivity of the joint. I can’t say what else can be used to solder aluminum besides these solders; I haven’t tried it. You can also solder with lead, the main thing is that the soldering iron has enough power and heats it up to a sufficient temperature.

Soldering iron

As mentioned above, aluminum has increased thermal conductivity, which is why cooling radiators are made from it. Therefore, for soldering large elements, the power of the soldering iron should be high, 100 - 200 W. If, of course, these are two small wires, then perhaps 60 - 100 W will be enough power.

Fluxes

Nowadays there are no problems with the choice of means, but previously I had to use anything to tin aluminum - aspirin, technical petroleum jelly, grease. For soldering aluminum at home, I chose two good fluxes F-64 and FTBf - And, the FIM flux also has good results. This is perhaps the most important thing, the better the flux, the easier the soldering.

The main thing is not to run into a fake, but there is enough of that now, you buy this “Flux for soldering aluminum”, but it’s no good. By the way, regarding the question of what else can be used to tin aluminum, there is such a flux F-34, this can be said just by its composition that it is aspirin. Aluminum can also be tinned with soldering oil.

Tinning methods

With good flux, the process of tinning and soldering is not a problem. It’s another matter if you don’t have one at hand, here the process becomes more labor-intensive.

The most important thing in the tinning process is to prevent contact of the surface being cleaned with oxygen. Therefore, the surface to be cleaned is thickly lubricated or filled with flux, and if necessary, it can be heated a little. You can simply, if the product is small, for example wires, clean them directly in the solution, pouring it into something.

Regarding the method of soldering aluminum with a soldering iron with a rosin solution, I did something like this. I pre-cleaned the surface, lubricated it with a solution and sprinkled it with copper or iron filings. Then, pressing with the soldering iron tip (the harder the better) and stripping off the oxide, I tinned it with regular solder.

Sometimes, if it was necessary to solder two wires, aluminum for example and copper, I used this method. I twisted the two ends of the wire and welded them with a current discharge using a graphite core from a battery. For such “welding” I used a 6-12 volt transformer with a current of 3 amperes. We connect one end of the wire from the transformer to a twist, and screw the battery rod to the second (you can use a brush from the engine). When touched, an arc appears and the ends are soldered into a ball.

So it’s quite possible to solder aluminum at home and it’s not that big of a deal. difficult task. A little practice and that's it.

Currently, aluminum and its alloys have become widely used in electrical appliances, such as aluminum electrical wires, etc. Since aluminum and its alloys quickly oxidize in contact with air, conventional soldering methods do not give satisfactory results. Below are described various ways soldering aluminum at home with tin-lead solders POS-61, POS-50, POS-90.

1. To solder two aluminum wires, they are pre-tinned. To do this, the end of the wire is coated with rosin, placed on sandpaper (with medium grain) and pressed against the sandpaper with a hot tinned soldering iron, while the soldering iron is not removed from the wire and rosin is constantly added to the desired end. The wire is tinned well, but all operations have to be repeated many times. Then soldering proceeds in the usual manner. The best results are obtained if, instead of rosin, you use mineral oil for sewing machines or alkaline oil (for cleaning weapons after shooting).

2. Soldering of sheet aluminum or its alloys is carried out as follows: rosin with fine iron filings is applied to the seam with a hot soldering iron. The soldering iron is tinned, and they begin to wipe the seam area with it, adding solder all the time. Sawdust, with its sharp edges, removes oxide from the surface, and the tin firmly adheres to the aluminum. Solder with a well-heated soldering iron. For soldering thin aluminum, a soldering iron power of 50 W is sufficient; for aluminum with a thickness of 1 mm or more, a power of 90 W is desirable; if the thickness is more than 2 mm, the soldering area must be heated with a soldering iron and only then apply flux and solder. Here, mineral oil can also be successfully used as a flux.

3. The original way soldering of aluminum wires and aluminum surfaces. Before soldering, the aluminum surface of the aluminum part is pre-copper-plated using the simple electroplating setup described earlier. But it can be made simpler.

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Rice. 1

To do this, take a thick brush for watercolor paints, and its metal rim, touching the hairs, is wrapped bare copper wire(Fig. 1). The other end of the wire is connected to the positive pole of the source direct current(rectifier, flashlight battery or rechargeable battery). The aluminum part is connected to the negative pole. The soldering area is cleaned with sandpaper. When starting to coat the part, you need to thoroughly moisten the brush in a saturated solution of copper sulfate and move it over the part, as when painting. After some time, a layer of red copper settles on the surface of the aluminum part, which, after washing and drying, is tinned in the usual way (with a soldering iron).

Note. In industry and repair practice, solders of the P150A, P250A and P300A brands are used for soldering mounting elements made of aluminum and its alloys, as well as connecting them with copper and other metals. Soldering is carried out with a conventional soldering iron, the tip of which is heated to a temperature of 350 ° C, using a flux that is a mixture of oleic acid and lithium iodide.

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Stages of tinning
Tinning of aluminum wires

To obtain a reliable connection when soldering with tin-lead solder, it is necessary to strip and tin the wires.

If you neglect these steps, it is unlikely that the soldering will be of high quality and durable.

First of all, you should prepare the soldering iron and, if necessary, carry out its maintenance: remove scale with a knife, clean the soldering iron tip using a fine-grained emery wheel or using a needle file.

Before starting soldering, the soldering iron must be warmed up to operating temperature. Then you should dip the tip into rosin, touch solid tin or tin-lead

If a thin shiny layer of solder has formed on the soldering iron tip (and not a hanging drop), you can proceed to further work.

All metals in the air oxidize. Their surface is covered with an oxide film, which prevents the metal from being wetted by molten solder. Therefore, all soldered surfaces must be cleaned to a metallic shine with a knife or fine sandpaper; additionally, they can be degreased with solvents.

Using a soldering iron, you need to warm up the wire, apply rosin to it, and rub solder into it with leisurely movements.

If the entire section of the conductor is evenly

digging with solder, tinning can be stopped.

Tinning copper wires does not cause any particular problems. Even novice solders can handle this job. But not all craftsmen know how to tin an aluminum wire.

It is difficult to solder aluminum wire at home; many craftsmen do not undertake such work.

How to solder aluminum

The problem is that if the oxide film is removed, the aluminum in the air almost instantly oxidizes and the film is restored. But with patience, you can get a fairly high-quality solder.

prepare flux by dissolving rosin in diethyl ether;
prepare steel filings;
strip the wire in the usual way;
immediately apply flux to the wire;
sprinkle the soldering area with metal filings;
Tin carefully by rubbing the solder into the aluminum.

Metal filings play the role of abrasive particles and constantly destroy the resulting oxide film.

As necessary, they should be poured onto the adhesion site.

This method does not always guarantee the achievement of the desired result. The contact between the soldered wires may be of poor quality and short-lived.

Professionals prefer to use special solders and fluxes. In this case, the soldered wire should be heated not with a soldering iron, but with a gas torch or blowtorch. The heating temperature of the solder and tinned wire must be at least 600°C.

Another simple way to tin aluminum wires using copper wires.

It is based on the phenomenon of electrolysis. To do this, you need to stock up on a concentrated solution of copper sulfate and a direct current source with a power of at least 10 W. Apply a few drops of copper sulfate to the cleaned aluminum at the soldering site and wrap it with several turns of copper wire.

An aluminum conductor is connected to the negative pole of the current source, and a copper conductor is connected to the positive pole. An electric current arises in the circuit, electrolysis occurs, and the aluminum conductor is coated with a thin layer of copper. A layer tinned with copper is formed on the aluminum conductor. This method cannot be used for tinning massive parts, but it is quite suitable for soldering thin conductors.

If copper sulfate is not available, it can be replaced with hydrochloric acid.

In the place of intended soldering, you need to move the copper conductor with pressure. Electrolysis in this case proceeds more efficiently. But you need to remember that the soldering area using acid oxidizes over time, so after finishing work it must be washed with clean water or a weak alkali solution.

Leather - Aluminum

The aluminum mold is not used to facilitate soldering and is produced after zinc treatment of the product and.

For soldering and tinning aluminum, use an ultrasonic soldering iron.

Aluminum in the air is known to quickly become covered with a layer of oxide film, which prevents the solder from bonding to the metal. Under the influence of ultrasound, the oxide film is destroyed and removed from the aluminum surface.

Aluminum is especially difficult to harden. Ultrasonic quenching, used for narrow seam soldering, is not suitable for thinning large surfaces such as aluminum tires.

At the Dynamo plant they developed a method for abrasive and abrasive crystal parts of aluminum tires.

Aluminum is especially difficult to clean. Ultrasonic hardening, used for soldering narrow gauges, is not suitable for thinning large surfaces of aluminum bars.

Aluminum is especially difficult to clean.

Ultrasonic hardening, used for soldering narrow gauges, is not suitable for thinning large surfaces of aluminum bars. At the Dynamo plant they developed a method for abrasive and abrasive crystal parts of aluminum tires.

In addition to ultrasonic soldering machines, abrasive solvents are used for abrasive processing of aluminum. Unlike conventional soldering irons, abrasive grinding parts 5 (Fig.

68), pressed from solder powder and asbestos, which acts as an abrasive.

Problems in soldering, welding and milling of aluminum and its alloys, due to the presence of an extremely stable oxide film on their surface, can be easily eliminated by ultrasound.

In addition to ultrasonic soldering machines, abrasive solvents are used for abrasive processing of aluminum.

Unlike conventional electric soldering irons, abrasive grinders have a working stick 5 (Fig. 68), pressed from solder powder and asbestos, which act as an abrasive.

An important advantage over the above mentioned methods of potassium aluminum is the use of ultrasound.

Ultrasonic soldering is used for soldering and tinning of aluminum.

Category: “Working with metal”

Aluminum in the air is quickly coated with a layer of oxide, which prevents the solder from bonding to the metal. Using ultrasound, the oxide film is crushed and removed from the surface, whereby the solder is exposed to the aluminum surface.

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Soldering any metal parts at home is not a difficult task; many boys, especially those who are passionate about radio engineering, can easily cope with it. For soldering, or tinning, you need a soldering iron itself (the most primitive one, requiring heating on a heat source, or a more advanced one - with an adjustable temperature), solder, flux and rosin.

Parts prepared for soldering are cleaned and degreased using sandpaper, gasoline or solvents.

Then flux is applied to the surface, which prevents oxidation processes on the parts being soldered.

Using a soldering iron, the tip of which is first dipped in rosin, solder is applied to the soldering site.

How to solder aluminum yourself

However, not everything is so simple - some metals and alloys are difficult to solder.

How to solder aluminum? The whole difficulty is that aluminum alloys oxidize in air in a fraction of a second, forming films that make soldering using conventional methods impossible.

However, there is a method that allows you to solder aluminum surfaces using the most ordinary soldering iron, solder and rosin.

Soldering aluminum will require a fairly powerful soldering iron (60-100 W), since this metal has very good thermal conductivity.

It may be necessary to additionally heat the parts to be soldered over the flame of a gas stove.

The secret is that the joint is rubbed with brick, sand, mortar and immediately filled with rosin.

Use a soldering iron tip to wipe the parts being soldered, removing the oxide film.

As a result, we get a very strong connection without any special costs.

Solder for aluminum, consisting of tin and zinc (tin and bismuth), coupled with a flux of paraffin and stearin, also gives a good result if the soldering site is protected from oxidation with rosin.

How to solder aluminum when it comes to wires? In this case, you can probably do without soldering altogether: for example, use a terminal strip.

If you need to connect wires in a limited space, where is it impossible to place a terminal block or similar connector?

Then it’s better to just twist it (wind the wire one on top of the other) and solder it and crimp it with pliers.

Flux for soldering aluminum, active, based on orthophosphoric acid, is quite accessible today.

You can buy it at any store that sells various types of radios - and electronic parts and components.

This is perhaps the easiest and most effective way to solder aluminum.

More on the topic:

The composition of fluxes for high-temperature soldering is given in the corresponding section.
The table shows the composition, temperature ranges of activity and purpose of some fluxes developed from 1973 to 1984. Among organic acids and other substances suitable as flux activators for soldering aluminum and its alloys at temperatures<300 °С, пригодны только алифатические кислоты, их амиды, а также триэтаноламин, имеющий свойства основания.

Among aliphatic acids, the most active are monobasic acids: stearic, elaidic, oleic, lauric, copric, caprylic, caproic, valeric, butyric, propionic, acetic, formic. The activity of these acids increases with increasing relative molecular weight and melting point. When they interact with Al2O3 oxide, the following reactions occur:

Al2O3 + 6RCOOH → 2 (RCOO)3Al + ZH2O (1)
2Al + 6RCOOH → (RCOO)3Al + ZN2 (2)

The reaction occurs most vigorously with formic and acetic acids, less vigorously with caproic acid.

However, the introduction of these acids into fluxes is of little promise due to their intense boiling at the soldering temperature and the decrease in the energy of COO-HC bond cleavage with increasing molecular weight of the acid. Salts of carboxylic acids obtained by reactions (1) and (2) are thermally unstable. For example, aluminum acetate decomposes at a temperature of 200°C.

Brand or number of flux	Flux composition, %	Temperature activity interval, °C	Note
1	4-7 ammonium borofluoride; 4-7 cadmium borofluoride; epoxy resin rest	<450	For soldering aluminum and Al alloy - 2% Mg(AMg2). High corrosion resistance
F59A	10±0.5 cadmium fluoroborate; 2.5±0.5 zinc fluoroborate; 5±0.5 ammonium fluoroborate; 82±1 triethanolamine	150-320	For soldering aluminum or AMts alloy with copper and steel with solders based on: Sn - Zn, Zn-Cd
F61A	10 zinc fluoroborate; 8 ammonium fluoroborate; 82 triethanolamine	150-320	For soldering aluminum, beryllium bronze, galvanized iron, copper with solders based on Sn - Zn, Zn - Cd
F54A	10 cadmium fluoroborate; 8 ammonium fluoroborate; 82 triethanolamine	150-320
3	7 bismuth bromide; 47.9 acetic acid; 55.1 oleic acid	<380	For tinning in liquid tin it is more active than F54A flux
4		<350	For tinning aluminum alloys, slightly corrosive and active
5	1.5 triethanolamine; 4 salicylic acid; 94.5 ethyl alcohol	150-320	For soldering aluminum with copper, beryllium bronze, galvanized iron with solders based on Sn-Zn and Zn-Cd
6	30 g lithium iodide; 200 ml oleic acid	<450	For soldering aluminum
7	4.2-10 titanium iodide; 16.8-22 rosin; caproic acid - the rest	<450
8		<450
9	10-15 zinc tetrafluoroborate; triethanolamine rest	≥350	For soldering aluminum wires with insulation (increases its stability) For soldering aluminum
10	7.5 aniline fluorohydrate; 92.5 rosin	<250
11	83 triethanolamine; 9 cadmium fluorine borate; 7 ammonium acid fluoride; 1 rosin	> 150

Among dibasic saturated acids, which are stronger than monobasic acids, the first three members of the homologous series of acids (oxalic, malonic, succinic) do not have activity when soldering aluminum, which is due to their decarboxylation when heated.

Higher acids have the same activity in fluxes as monobasic acids, with the same number of atoms in the radical.

Acid anhydrides are not active during soldering. Halogen-substituted acids have higher activity in fluxes for soldering aluminum, which is explained by the simultaneous effect of both the carboxyl group and the halogen atom on aluminum oxide.

It was discovered that some solid amino acids are active in fluxes: α-aminopropionic and phenylanitronyl, which ensure good spreading of solder.

Taking into account the physical properties, degree of toxicity and activity in fluxes among organic acids, the most suitable can be considered higher liquid unsubstituted acids, their solid analogues and amino acids.

The fluxing ability of mixtures of acids in any ratio does not exceed the activity of the component with the highest molecular weight.

Salicylamide and urea are equivalent in activity to caproic or elaidic acid.

Adding salts to acid solutions

The activity of ammonium salts of organic acids is close to the activity of the original mono- and dibasic acids. These salts have advantages over amides - less volatility during soldering and better solubility in acids.

It is characteristic that the introduction of organic acids and their derivatives into triethanolamine does not increase its activity when fluxing aluminum alloys.

A further increase in the fluxing activity of acidic organic solutions is achieved by adding halide salts of amines or metals to them.

The introduction of LiI and SnCb into decyl alcohol (boiling point 231°C) or into caproic acid (boiling point 205°C) LiBr, LiI, NaI, SnCb in the form of crystalline hydrates activates the solution.

The introduction of 95% ethyl alcohol into acid fluxing salt solutions deactivates them due to the displacement of water according to the reaction:

Al (OR)3 + 3H2O → Al (OH)3 + 3ROH.

However, the presence of water of crystallization in an alcohol solution of tin chloride does not affect its activity during soldering

Reactive organic fluxes

Reactive organic fluxes have been proposed for soldering aluminum with low-melting solders.

The basis of these fluxes is the organic amino alcohol triethanolamine, and the activators are fluoroborates of heavy metals and ammonium. At the points of contact of fluoroborates with aluminum, metals are deposited through discontinuities in the Al2O3 oxide film: cadmium and zinc. During heating, triethanolamine residues transform into an inert, resin-like substance that does not cause corrosion of solder joints. These fluxes and their residues after soldering have pH = 8, which also confirms their non-corrosive activity.

All these fluxes do not differ in corrosive activity when soldering aluminum, but when soldering it with the AMts alloy, copper and its alloys, the F59A flux is the most effective. The temperature range of activity of these fluxes is 150-300°C. Fluxes of this type are unsuitable for lap soldering with solder placed at the gap of deformable alloys AMg, D1, D16, V95 and cast aluminum alloys. They can only be used when tinning the soldered aluminum surface followed by soldering, for example with LTI-120 flux.

In this case, the temperature between the soldered parts during soldering should not differ by more than 10°C.

How to solder aluminum with a soldering iron

Residues of fluxes are easily washed off with water or wiped with a damp cloth moistened with water or ethyl alcohol, and do not cause any noticeable corrosion for more than 1000 hours. Studies have shown that, in comparison with fluxes containing acetic, nylon, oleic, lauric as a solvent acids, and bismuth chloride as an activator, F54A flux provides a large area of spreading of P250A solder over AD1 aluminum; but it is less active in soldering corrosion-resistant steel, brass and copper than fluxes containing bismuth chloride.
Fluxes F54A, F59A and F61A are suitable for soldering in the specified temperature range with P200A, P250A, P300A, P170A and P150A solders.

To do this, use temperature-controlled electric soldering irons, induction heating, and soldering by immersion in molten solder. Soldering with these fluxes when heated with an open flame is unacceptable due to the possibility of their combustion. At temperatures above 350 °C, solder joints are formed in the soldered seams of contacting joints made with these fluxes. With rapid heating (electrical contact, induction methods) in pure argon, soldering with these fluxes is possible at a temperature of 320 °C.
There is data on the use of low-melting solder Sn - (8-15)% Zn - (2-5)% Pb with a melting point of 190 ° C with flux in the form of a solution of boron-fluoride and ammonium fluoride in monoethanolamine for soldering aluminum alloys.

In fluxes for low-temperature soldering of aluminum and its alloys, instead of rosin, it is proposed to use pentaerythritol benzoate, which is more heat-resistant than rosin, and its residues are non-corrosive and, in the form of an elastic film, protect solder seams from oxidation. Carboxylic acids are used as flux activators. Soldered joints (P250 solder) are not destroyed in a saline solution for 200 days. Solder wire (Sn-Pb-Ag) with a core of the specified flux is suitable for soldering all aluminum materials that contain less than 3% Mg and 3% Si.

Craftsmen have no problems with soldering copper, brass and steel wires and parts, but if we have to deal with aluminum surfaces, the solder does not hold the product, and soldering turns into torture. The problems are caused by the fact that a thin but very strong oxide film of Al2O3 forms on the surface of this metal. This film can be mechanically removed - for example, to clean the product with a nail sticker - but when it comes into contact with air or water, the metal will immediately be coated with the film.

Despite the problems we face, aluminum products can be soldered. There are several ways to solder aluminum.

Soldering of aluminum alloys

Excellent results can be obtained with the following alloys:

two parts zinc and eight pieces tin
one piece of copper and 99 pieces of tin
one piece of bismuth and 30 pieces of tin

Before soldering, both the alloy and the part must be well heated.

You should also remember that soldering acid should be used in this soldering method.

Aluminum soldering with special currents

Standard currents do not dissolve the oxide film on the surface of aluminum, so special active currents must be used.

Aluminum soldering flux is used to work with pliers with a working temperature of 250-360 degrees. This flow, during soldering and hardening, clears the oxide film, cleans the metal surface and, therefore, the solder spreads better over the surface.

All this leads to the creation of a tighter and more durable connection of the molten parts. Excess of this flow can be easily removed with solvents, alcohol or special liquids.

Other methods of soldering aluminum

There are also non-standard ways to solve this problem, for example:

Thoroughly clean the soldering iron of any aluminum products and add a few drops of concentrated copper sulfate.
A small piece of copper wire, peeled in a circle with a diameter equal to the soldering point, and the free end of the wire is connected to the "plus" output of the battery for 4.5 volts. A piece of wire with a rolling circle falls onto a small amount of copper sulfate. The negative battery should be connected to the part on which a certain layer of copper will be installed after a certain time.

How to Solder Aluminum Using a Tin Can

Once dry in this room, you can usually weld the necessary parts or wires.
In this case, use abrasive powder with a small amount of transformer oil to obtain a liquid paste.
This paste is used for refined soldering products. Then the soldering iron is good and apply these places until the tin layer is separated on the surface. Then rinse the parts and then solder as usual.
This method requires a transformer.
Its disadvantage is associated with the product, and the connection is connected to a copper wire of a large part, consisting of small vessels. If you connect this wire to a future soldering site for a short time, a micro-soldering joint of copper and aluminum will be made, which will allow the wire to be connected in the normal way in the future.

To simplify the process, you can use soldering acid.

Soldering aluminum utensils (without soldering iron)

Some household needs use aluminum accessories, sometimes it breaks and does not buy a new one (which is very expensive), you can fix these products by soldering without a soldering iron.

The following method is suitable for sealing small holes (up to 7 mm in diameter).

The soldering point should be cleaned with a metallic shine using sanding paper or a file. If the containers are enameled, the holes around the enamel must be removed within a radius of 5 millimeters.
To do this, the light touches a hammer from a container, which is thrown away by the enamel. Then you need to clean the metal.
The soldering point is lubricated with blown acid or covered with earth rosin. From the inside, a piece of the pot is placed over the hole and then the heater is heated over the fire of the stove.
If the containers are enamel, it is preferable to heat them over a light bulb - this allows the area to heat up more, so the other sponges are not affected by the heat.
When heated, the mucus melts and closes the hole in the pan.
At the same time, a soldering iron is not needed.