Hello my dear readers! Soldering aluminum interested me 5 years ago, when I had to urgently solder the cooling radiator of my Grasshopper. Below I will show his photo and the place of soldering on the radiator, which is still working. Recently I was asked what is the best way to solder aluminum? I decided to read all the sane articles and personal opinions on aluminum brazing and put it on one page. Thus this article was born. Go!

Why is aluminum hard to solder?

Anyone who has tried to solder aluminum knows that ordinary solder does not stick to it at all. All because of the stable aluminum oxide film, which has poor adhesion to solder. Moreover, this film covers aluminum and its alloys very quickly. You will not have time to clean it - the light metal has already oxidized. Therefore, all methods of soldering aluminum fight first with the film, and then take care of adhesion.

Aluminum oxide (Al 2 O 3) in mineralogy is called corundum. Large transparent crystals of corundum are precious stones. Due to impurities, corundum is colored in different colors: red corundum (containing chromium impurities) is called ruby, and blue is called sapphire. Now it is clear why the oxide film is not soldered at all.

How to remove the oxide film?

The aluminum oxide film is removed in two ways: mechanical and chemical. Both methods remove aluminum oxide in an airless environment, that is, without access to oxygen. Let's start with the most difficult, but the most correct and reliable method of removal - chemical.

Precipitate copper or zinc

The chemical soldering method is based on the preliminary deposition of copper or zinc on aluminum by electrolysis. To do this, a concentrated solution of copper sulphate is applied to the right place and the minus of the battery or laboratory power source is connected in a free place. Then they take a piece of copper (zinc) wire, connect a plus to it and immerse it in the solution.

Through the electrolysis process, copper (zinc) is deposited on aluminum and sticks to it at the molecular level. Then aluminum is soldered over the copper. True, it is not clear how all this passes through the oxide barrier. I think that this instruction skipped the stage of scratching aluminum under a film of copper sulfate or other chemical exposure. Although the practice from the video below shows that you can not scratch.

After deposition of copper or zinc without problems with standard fluxes. It seems to me that this method makes sense to apply on an industrial scale and for especially responsible work.

Use oil without water

The second most difficult method is to remove alumina. At the same time, the oil should contain a minimum of water - transformer or synthetic oil is suitable. You can hold the oil at a temperature of 150 - 200 degrees for several minutes so that water evaporates from it and it does not splash when heated.

Under the oil film, you also need to do the removal of oxide. You can rub with sandpaper, scratch with a scalpel, or use a serrated sting. When I needed to solder the engine cooling radiator, I subtracted the chip method. We take a nail, saw it with a file to get steel shavings.

Next, apply oil to the place of soldering and pour shavings. With a soldering iron with a wide tip, we are trying to rub the place of soldering, so that there are chips between the tip and aluminum. In the case of a massive radiator, I additionally warmed the place of tinning.

Then we take the solder on the tip with a drop, immerse it in oil at the place of soldering and rub it again. For better tinning, rosin or other flux can be added. There is a so-called surfacing under a layer of flux. The video shows well soldering aluminum with oil.

Solder with active flux

There are separately developed active fluxes for aluminum brazing. Usually they include acids (orthophosphoric, acetylsalicylic acid) and salts (sodium salt of boric acid). Strictly speaking, rosin also consists of organic acids, but in practice it gives a weak result on aluminum.

Due to their activity, acid fluxes must be washed off after soldering. After the first wash, you can additionally neutralize the acid with alkali (soda solution) and rinse a second time.

Active fluxes give a good and fast result, however, it is directly forbidden to inhale the vapors of this flux. Vapors irritate mucous membranes, damage them or can enter the bloodstream through the respiratory tract.

Fluxes for aluminum brazing

Consider all common fluxes for soldering aluminum.

Rosin

Liquid fluxes are good because they can be applied in a thin layer. They evaporate more actively and often have burning vapors. More designed for soldering with a soldering iron.

• Flux F-64 contains tetraethylammonium, fluorides, diionized water, wetting agents and corrosion inhibitors . It is capable of destroying a strong oxide film of considerable thickness, which means it is suitable for soldering large workpieces. Suitable for soldering aluminum, galvanized iron, copper, beryllium bronze, etc.
• Flux F-61 contains triethanolamine, zinc fluoroborate, ammonium fluoroborate. It can be recommended for low temperature soldering at 250 degrees or tinning of aluminum alloy products.
• Castolin Alutin 51L contains 32% tin, lead and cadmium. This composition works best when using solders from the same manufacturer at temperatures of 160 degrees and above.
• There are, but I won’t list them - everyone should be equally good.

Solder for aluminum soldering

Solder HTS-2000

This is the most advertised solder. Soldering aluminum with it is very easy. Watch the HTS-2000 solder promo video from New Technology Products (USA). They say that it is even better and stronger than aluminum. But it is not exactly.

And here is the real experience of soldering with solder HTS-2000. The solder sticks badly at first, but then it seems to even come from. The pressure test showed that the soldering site was poisoning. There is an opinion that HTS-2000 should only be soldered with flux. Draw your own conclusions.

Solder Castolin

Solder Castolin 192FBK consists of aluminum 2% and zinc 97%. 192FBK is practically the only solder for soldering aluminum to aluminum in the list of offers of the French company Castolin. There is also AluFlam solder 190, but it is designed for capillary soldering and does not have flux inside. Also in the line there is Castolin 1827 solder, designed for soldering aluminum with copper at a temperature of about 280 degrees.

Castolin 192fbk solder tube contains a flux in the core, so you can solder without the recommended Castolin Alutin 51 L liquid flux. The video below shows the soldering process. Good solder - you can take it at a price of 100 - 150 rubles. per bar weighing 10 grams.

Solder Chemet

Solder Chemet Aluminum 13 used for welding aluminum and its alloys, with a melting point above 640 degrees. It consists of 87% aluminum and 13% silicon. The solder itself melts at about 600 degrees. The cost is about 500 rubles. per 100 grams, in which as many as 25 bars.

His older brother Chemet Aluminum 13-UF has a flux inside the tube, but it costs more - 700 rubles. for 100 grams and 12 bars.

I did not find any sane videos on soldering with this solder. Of course, this list of solders is not exhaustive. There are also Harris-52, Al-220, POC-80, etc.

Domestic solders

• • . Why not? When I soldered an aluminum heatsink, I only had this one on hand. And it has held up well for 5 years.
  • Aluminum solder 34A- for soldering with a gas-flame torch, in a furnace in a vacuum or with immersion in a melt of aluminum salts and its alloys, except for D16 and containing> 3% Mg. Melts at 525 degrees. Well solder aluminum alloys AMts, AMg2, AM3M. For 100 grams you will have to pay about 700 rubles.
  • Solder grade A- made in accordance with TU 48-21-71-89 and consists of zinc by 60%, tin by 36% and copper by 2%. Melts at 425°C. 1 bar weighs about 145 grams and costs about 400 rubles.
  • SUPER A+ used with SUPER FA flux and manufactured in Novosibirsk. Positioned as an analogue of the HTS-2000. For 100 grams of solder they ask about 800 rubles. There are no reviews yet.

Comparison of solders for aluminum brazing

In this video, the Master compared the HTS-2000 solder with Castolin 192fbk and the domestic Aluminum Cucumber solder. The cucumber is practically aluminum, so its strength is high, but it must be soldered in the oven. Reviews of HTS-200 solder are extremely negative, and Castolin 192fbk solders well and has good wettability when heated.

Another Craftsman compared HTS 2000 with Fontargen F 400M flux and Castolin 192FBK solder.

The results are:

• HTS 2000- ductile solder, you have to resort to steel tools to level the solder on the metal surface. With flux, the situation is much better.
• Castolyn 192FBK- high fluidity and flowability. Small holes are soldered with it quickly. It is difficult for them to solder large holes - it can fall into the radiator.

Cored wire

Flux cored wire - needed for welding aluminum, not for soldering. Do not confuse these two concepts. The advantage of this wire is welding without the use of gas. This is an electric welder for aluminum. Interesting stuff, but expensive. I will show a good video about welding with flux-cored wire.

Soldering iron for soldering aluminum

Soldering aluminum with a soldering iron must take into account the area of ​​\u200b\u200bthe parts to be soldered. Aluminum, like copper, is a good conductor of heat, which means that more heat should come from the soldering iron than the soldered parts dissipate.

An approximate calculation is 1000 sq. see aluminum can effectively dissipate about 50W of heat power. It turns out to solder two parts with a total area of ​​​​1000 square meters. see, you need to take at least. Then soldering aluminum will be fast enough not to turn into torture.

You can solder with a low power soldering iron. For example, when I soldered the radiator of my Grasshopper with a 60 W soldering iron, a hot air soldering station helped me, which acted as a heating.

Aluminum brazing torches

When the power of the soldering iron and heating is not enough to solder, for example, thick aluminum sheets, then they come to the rescue.

I already wrote a separate article about burners -. The power and size of the burner nozzle also depends on the areas that need to be heated. The advantage of the heating pad is the non-contact transfer of heat and the high speed of heating. Often the edges of the workpiece do not have time to heat up, and the joint is already soldered.

Observe safety precautions when working with burners!

Here's what you can do with a simple canister burner.

Which is better - aluminum welding or brazing?

Disputes in answering this question do not think to subside. It turns out it all depends on your purpose. More precisely, the purpose of your connected parts.

If you need to solder a car radiator, then aluminum soldering is better, because it's cheap. For critical work (bearing structures) and food containers (for example, a milk flask), welding is better suited, because it is more reliable. Here is how I would formulate the answer to this question.

It is clear that it is easier for a Master with gas welding to brew a radiator, rather than soldering it, and vice versa - it is easier for a Master with a soldering iron to solder.

Now look at TIG welding for beginners. Very helpful and well filmed.

How to make money soldering aluminum?

And now the most interesting thing is how and how much to earn on soldering aluminum. I opened Avito and scoured aluminum brazing cost. Here's what happened:

• soldering a car radiator, refrigerator, air conditioner - from 1000 rubles.
• soldering electrical wires - 15 rubles. for soldering.
• repair of bicycle frames - from 500 rubles.
• soldering aluminum for food, for example, pans - from 100 rubles.

Expenses:

• Gas cartridge with a burner 700 - 1000 rubles.
• Solder Castolin 192FBK - 150 rubles. per bar * 5 = 750 rubles.
• Training radiator - free of charge or for 500 rubles. in scrap metal.
• Desire is priceless!

Business plan:

1. Spend 2000 rubles. for tools and experience
2. Recapture the cost of 2 repairs.
3. There will still be at least 3-4 repairs left.
4. Profitability 200 - 300%!

And now the promised one. This is what my radiator looked like.

At this point, the fan shroud bent from heating and began to rub against the radiator. Three holes formed through which the antifreeze popped. I remember this night. Good thing it was within the city.

In the entire Rostov region, I saw only one such machine. Once in the city of Kamensk-Shakhtinsky, we stood at a traffic light one after another. It looked funny.

That's all. I hope that now aluminum soldering is not something special for you. The Soldering Master worked for you. How do you solder aluminum?

Hi all! Many people know that aluminum is soldered mainly in an argon environment with a special welding machine, but there is another option for working with a gas burner, and even a turbo lighter can be used on a small scale.

In general, this is not my first acquaintance with this wire, but the shopping experience is not very good, so I will share not only the test result, but also proven places to buy, so as not to get sample number 2, but let's start in order.

Characteristics

Diameter: 2.0mm
Length: 500 mm
Soft solder ISO 3677:~B-Zn98Al 381-400
Approximate composition (weight%): 2.4 Al - the rest is Zn
Melting point ºС: 360
Tensile strength (MPa): Up to 100 (Al)
Density (g/cm3): 7,0

Unpacking and appearance

The last and most profitable acquisition was sample no. 3 from banggood.

Came in a small gray package

The rod is additionally packed in a transparent zip-package.

5 meters cost me $8 with points, that is $1.6 per meter

White powder flux is visible in the center, the rod is moderately hard, looks like aluminum without oxidation

Comparison

The one on the far left was bought first. sample number 1 in Ali. It is absolutely identical in properties to sample number 3, but 3 meters cost me $12 , that is $4 behind meter which is almost three times more expensive. check current price

In the center sample number 2. It costs $5 3 meters or $1.7 behind meter, like sample no. 3

But as soon as you take the bag in your hand, you understand that this is a POS with a not very thick flux inside.

Two more samples $8 over 3 meters were never delivered, probably they were not even sent.

Testing

Aluminum eventually becomes covered with an oxide film, due to which the surface becomes matte, and so, before soldering surfaces must be cleaned to a shine, otherwise the solder will simply roll over the surface in balls, regardless of the degree of its heating. Sample #1

In general, it is correct to heat the part to a temperature of about 400 degrees, and then simply drive the rod, which will melt and fill the gaps, but I have little experience, so in order not to overheat the surface, I periodically bring the rod into the burner flame. If the temperature is low, the solder will roll over the surface in a ball, if it is sufficient, it will tin it.

The fracture test shows a good result - the break does not occur along the seam

Sample #2. It melts very well, emits a lot of smoke, stinks of burnt "aspirin". It sticks to aluminum, but if overheated, it burns out pretty quickly.

It is inconvenient to work because of the stench and the need to control the temperature.

Sample #3. I decided to solder the tubes with the outer walls

Trying to break the seam. After the tube popped out of the vise, I clamped it higher, taking it out of focus and noticed this only at the stage of creating gifs

But there is a photo of the result, which shows that the seam was not damaged.

And finally, let's splice an aluminum tube with a piece of "duralumin"

The tear test was also successful.

Results

An interesting wire - aluminum solders perfectly, filling even small gaps with itself, the main thing is that the joints are not dirty. It also sticks well to copper, but experienced people say that it is better to use other alloys to work with it, although this bar will also work for emergency field repairs.

The melting point of aluminum is about 660ºС, it would seem that you can use rods at 450-500 degrees, but you may encounter two problems:
1. A massive part up to 500 degrees needs to be warmed up with something else
2. You can overheat the soldering point and ruin the part

It seemed to me the best sample no. 3. Corresponds to the declared characteristics and is cheaper than the rest at least twice. There are also lots of different lengths to choose from:
1 meter - $2.89
2 meters - $4.39
3 meters - $6.39
5 meters - $9.89

Soldering aluminum, as many experts rightly believe, is a rather complicated technological process. Meanwhile, such an opinion can be considered true only in relation to those situations when they try to solder aluminum products using solders and fluxes that are used to connect parts from other metals: copper, steel, etc. If a special flux is used for soldering aluminum , as well as the corresponding solder, then this technological process does not present any particular difficulties.

Process features

Soldering aluminum with traditional solders and fluxes is difficult due to a number of factors, mainly related to the characteristics of this metal. The main of these factors is the presence of an oxide film on the surface of aluminum parts, which has a high melting point and exceptional chemical resistance. Such a film during soldering prevents the connection of the base metal and the material of the solder.

Before soldering aluminum products, their surfaces must be thoroughly cleaned of the oxide film, for which you can use machining or apply fluxes, which include strong components.

Aluminum itself, unlike the oxide film on its surface, has a fairly low melting point: 660 degrees, which also complicates the soldering process. This characteristic of aluminum leads to the fact that when heated, parts from it quickly lose strength, and at a certain temperature, which is in the range of 250–300 degrees, structures made of this metal begin to lose stability. The most fusible component, which is part of the most common aluminum alloys, begins to melt already in the temperature range of 500–640 degrees, which can lead to overheating and even melting of the parts to be joined.

Most of the low-melting solders used for soldering are based on tin, cadmium, bismuth and indium. With these elements, aluminum does not join well, which makes the solder joints obtained with their use very fragile and unreliable. Aluminum and zinc have good mutual solubility, so this element, when used in solders, provides the resulting joint with high strength.

Materials used

When performing soldering of aluminum products, solders of the tin-lead group can be used if the surface of the parts is thoroughly cleaned and highly active fluxes are used. The compounds obtained with their help, due to the poor mutual solubility of aluminum, tin and lead, are not very reliable, and they are also prone to the development of corrosion processes. To make such joints more resistant to corrosion, they must be coated with special compounds.

The most high-quality, reliable and corrosion-resistant solder joint, allows you to get solders, which contain zinc, copper, silicon and aluminum.

Solders that include these elements are produced by both domestic and foreign companies. The most common domestic brands are TsOP40, which contains 40% zinc and 60% tin, and 34A, which contains aluminum (66%), copper (28%) and silicon (6%). Zinc contained in solder for soldering aluminum products determines not only the strength of the resulting joint, but also its corrosion resistance.

Tin-lead solders have the lowest melting point of all of the above. The highest temperatures are those containing aluminum and silicon, as well as materials containing aluminum together with copper and silicon. The latter, in particular, include solder of the popular brand 34A, the melting point of which is in the range of 530–550 degrees.

For information: materials based on aluminum and silicon melt at a temperature of 590-600 degrees.

Given the melting point, such solders are used in cases where it is necessary to connect large-sized aluminum parts, which provide good heat dissipation, or products made of aluminum alloys that melt at sufficiently high temperatures.

But, of course, low-temperature solders, one of the most common brands of which is HTS-2000, demonstrate maximum convenience in work.

Aluminum soldering technology necessarily involves the use of a special flux, which is necessary in order to improve the bondability of the base metal with the solder material. That is why it is necessary to approach the choice of such material very responsibly. This requirement is especially relevant in cases where aluminum parts must be soldered using tin-lead solder. The composition of fluxes contains elements that form its activity in relation to aluminum. These elements include: triethanolamine, zinc fluoroborate, ammonium fluoroborate, etc.

One of the most popular domestic materials is F64 flux. The popularity of F64 is due to the fact that this material is characterized by increased activity. Thanks to this quality, it is possible to perform soldering with F64 flux without even cleaning the surface of aluminum parts from a refractory oxide film.

Of the popular high-temperature fluxes, the 34A grade material should be distinguished, which includes 50% potassium chloride, 32% lithium chloride, 10% sodium fluoride and 8% zinc chloride.

Part preparation

To obtain a high-quality and reliable connection, it is not enough just to know how to solder aluminum, it is also important to correctly prepare the surfaces of the parts to be joined for soldering. Such preparation consists in degreasing the surfaces and removing the oxide film from them.

For degreasing, traditional means are used: acetone, gasoline or any suitable solvent.

Removing the oxide film before soldering, which is also easy to do with your own hands, is mainly done by machining, for which you can use a grinder, sandpaper, a metal brush or a stainless wire mesh. Much less often, a chemical method is used to remove such a film, which involves etching the surface of aluminum parts using acid solutions.

As you know, an oxide film on the surface of aluminum is formed almost instantly when it comes into contact with the surrounding air. This process also occurs on the surface cleaned before soldering, but the meaning of stripping is that the newly formed film is much thinner than the removed one, so it will be much easier for the flux to cope with it.

Heating sources

As an element with the help of which the overall aluminum parts to be joined are heated and the solder is melted, a propane or butane gas burner is mainly used. If you decide to solder aluminum products with your own hands in a home workshop, then you can use an ordinary blowtorch.

When heating, care must be taken to ensure that the parts to be joined do not melt. To this end, the surface of the parts is touched with solder as often as possible in order to control the beginning of its melting. This will indicate that the operating temperature has been reached.

When heating parts and solder before soldering, it is also necessary to monitor the flame of a gas burner: the mixture of gas and oxygen that forms it must be balanced. This is necessary for the reason that a balanced gas mixture actively heats the metal, but does not have a serious oxidizing effect. The fact that the gas mixture is balanced is evidenced by the bright blue color of the flame, which has a small size. If the burner flame is too small in size and has a pale blue color, then this is an indication that there is too much oxygen in the gas mixture.

For soldering small aluminum products, electric soldering irons and solders that melt at a low temperature are used.

Technological methods of soldering

Soldering parts made of aluminum, according to the execution technology, is practically no different from the process of joining products made from other metals. First, the parts to be joined are degreased and thoroughly cleaned, after which they are placed in the desired position relative to each other. Then it is necessary to apply a flux to the zone of the future connection and start heating it together with the solder to the operating temperature.

When the operating temperature is reached, the tip of the solder will begin to melt, so they need to constantly touch the surface of the parts, controlling the heating process.

Soldering aluminum products, for which flux-free solder is used, has its own characteristics. They consist in the fact that in order to prevent the penetration of the solder to the surface of the part by the oxide film, its tip must be made to strike at the place of the future connection. Thus, the integrity of the film is violated, and the solder is freely connected to the base metal.

To see how soldering is done in practice, you can watch the training video.

There is another technological technique that allows destroying the oxide film during the soldering process. This can be done using a stainless steel rod or a metal brush, which is driven over the junction and the already molten solder.

To obtain the strongest connection possible by soldering, the surfaces to be joined must be pre-tinned.

Scope of the process

Of great practical importance is not only soldering aluminum at home. This technology is also actively used in repair and manufacturing enterprises. Using the soldering method, it is possible to obtain joints that are characterized by high strength, reliability and aesthetic appeal.

This technology is very popular when performing repair work with vehicles, tractors and motorcycles. Such popularity is explained by the fact that during soldering there is no change in the structure of the metal being joined, therefore, in many cases, such a connection method is even more preferable than welding.

Soldering has practically no alternative when it is necessary to restore the tightness of an aluminum radiator or crankcase, to repair a worn or destroyed part made of aluminum alloy. It is also convenient that you can do such repairs with your own hands, this does not require complex and expensive equipment.

Burnouts, chips and cracks formed in an aluminum alloy cylinder block can also be successfully repaired by soldering. This technology is very useful in the event that it is necessary to restore worn internal threads. In this case, the worn threaded hole is filled with molten solder, and then a bolt is screwed into it. After the solder hardens, the bolt is turned out of the hole, and inside it is a thread formed according to the required parameters. Such a simple operation allows you to get a new thread, which in terms of its strength characteristics is in no way inferior to the original one.

In addition, soldering is successfully used to repair and restore the tightness of pipes made of aluminum and alloys of this metal. Such pipes are now actively used in many technical devices. With the help of soldering, you can do it yourself, without resorting to the expensive services of qualified specialists, to repair many items made of aluminum and its alloys used in everyday life: dishes, stairs, various interior details, gutters, siding elements, etc. Using soldering, you can not only to repair, but also to make any structures from aluminum with their own hands.

The use of high-quality consumables and strict adherence to technology, which is not difficult to learn from video tutorials, allows you to obtain connections by soldering that are of high quality, reliability, attractive and neat appearance.

Using improvised means

There are often situations when there is no active flux and solder at hand, which is specially designed for joining aluminum parts, and they need to be soldered urgently. In such situations, soldering can be done with conventional solder consisting of aluminum and tin or tin and lead. In this case, rosin can be used as a flux.

When using this soldering method, the oxide film is destroyed under a layer of rosin, to which metal filings can be additionally added. To destroy it, a special soldering iron with a scraper is used, which must first be tinned. The scraper, along with sawdust, destroys the oxide film on the surface of the parts, and the rosin prevents the formation of a new one. In addition, a scraper-soldering iron, moving the molten solder at the place of the future joint, ensures its tinning.

How to solder aluminum at home

Soldering wires with solder is considered the most reliable method of connecting wires and cable strands. Well, if you need to solder only copper wires, which are easily soldered. It is not for nothing that in electronics all the output elements are copper, tinned.

Soldering aluminum at home

Once solid wires and stranded cables have been irradiated, they are fairly easy to connect by soldering. And how to solder aluminum with tin, if the solder is rejected by aluminum oxide. As you know, aluminum is covered with a thin layer of oxide, which instantly forms on aluminum in contact with oxygen. In order for the solder to adhere well to the aluminum wire, you need to remove the aluminum oxide, and then tin.

For this purpose, as a flux, there are: soldering acid, special fluxes for aluminum, a mixture of rosin with acetone. All these pluses destroy or hinder the formation of an oxide film on aluminum. After applying this type of flux, the process of tinning aluminum is simplified.

The necessary tools for soldering aluminum with tin are: an electric soldering iron, a sharp knife, pliers for twisting wires, a small file for preparing a soldering iron tip. Of the materials you will need: solder POS 61 or POS 50, flux for soldering aluminum F-64 or similar, sponge.

Soldering aluminum with tin and flux Ф 64

Flux F 64 is designed for soldering aluminum. The soldering technique is not difficult. First of all, you need to remove the insulation from the wires by 5 cm. The insulation is removed with a sharp knife at an angle to the wire so as not to cut it. Notched aluminum breaks off easily.

Tools and materials for soldering aluminum wire

Next, you need to clean the wire well with fine sandpaper or a sharp knife. After stripping the wire, it is moistened with a brush with a plus and a sharp knife continues to strip the wire, but already under a flux. In this way, the film of aluminum oxide is removed from the wire, preventing it from oxidizing again in air. Next, a heated soldering iron with solder begins tinning the wire from its end.

If you start tinning the wire near the insulation, then you can set it on fire. In this case, the insulating properties of the wire will be lost. The wire is soldered with a soldering iron, moving back and forth, at the same time the oxide film is removed from aluminum. It will not work right away to irradiate the wire exactly. Therefore, flux is again applied to the non-tinned sections of the wire and the remaining oxide film is removed with a hot soldering iron with solder and moving back and forth and serviced.

Thus, the aluminum wire is completely covered with solder. After tinning, the aluminum wire is dipped into a soda solution (5 tablespoons per 200 g of water) and the remaining flux is washed off with a toothbrush. The composition of the flux includes active acids, which not only corrode the film, but also the wire itself. Therefore, the flux residue must be washed off. It will not be possible to wash it off completely, since it partially remains under the solder and eats into the wire.

But at least some of it needs to be washed off. Copper wire is not serviced with F 64 flux, it is better to use a solution of rosin and alcohol (50% to 50%). Liquid rosin is applied to the copper wire with a brush (after stripping it) and the wire is serviced with a hot soldering iron, starting from the end. The tip of the soldering iron should be smooth and clean. The sinks at the end of the soldering iron tip are removed with a small file.

And the remnants of the burnt solder (slag) are wiped with a sponge or rag. As soon as the aluminum and copper wires are tinned, they are twisted with pliers, liquid rosin is applied with a brush and the connection is soldered, also starting from the end. If you connect aluminum without tinning with solder, then this connection may be broken over time. The connection of aluminum with copper is a galvanic pair, and when a current passes through it, it heats up and destroys the connection.

Table of temperature regimes of solder grades

As a result, the place of twisting is very hot and charred, which increases the fire hazard. Tin solder is neutral to aluminum, so aluminum wires must be tinned before connecting to copper. Solder POS 61 and POS 50 with a low melting point of 190 - 210C are well suited for soldering aluminum wires.

Soldering aluminum with copper, tin and rosin

Soldering electrical wires with soldering acid is prohibited in the PUE. This is due to the fact that this acid does not completely burn out during soldering. As a result, the junction of the wires is corroded over time by acid, oxides are formed that heat up when current passes and can cause a fire in the insulation. Such acidic fluxes include special fluxes for aluminum brazing, including F 64.

So how to solder aluminum with copper so that the connection is of high quality and durable. In terms of complexity, the method of tinning aluminum with tin and rosin is even easier than tinning aluminum with F 64 flux. But the quality and reliability of tinning in rosin will be high. When tinning aluminum in rosin, you need to make or pick up a low bath for liquid rosin (60% rosin and 40% alcohol).

Fluxes for aluminum brazing

Fill the bath with liquid rosin so that the wire is buried in it with 5-10 mm insulation. The wire, cleaned of insulation, is placed in rosin and with a sharp knife (conveniently with a scalpel) the oxide film is removed from the aluminum wire without removing it from the bath. That is, under the rosin protect the wire along its entire length from all sides. Under the rosin, a film does not form on the cleaned places of the aluminum wire, since there is no contact with oxygen.

Now they take a heated soldering iron with a solder with a power of at least 60 W and lowering it onto a bare and oxide-free wire, near the very surface of the rosin, they gradually scroll and pull out the already tinned sections of the wire. The essence of the method is that the wire is tinned at the very surface of liquid rosin. So that the stripped sections of the wire from oxide cannot come into contact with air.

The soldering iron may at times be immersed 2-3 mm in rosin. After a little irradiation of the wire, raise the soldering iron so that it heats up again. Yes, in the beginning, there will be a lot of smoke, so it is better to learn how to solder outdoors or in a well-ventilated room. After several attempts, you will develop your own tinning technique and gain some experience.

You will decide on the position of the soldering iron, the speed of tinning the wire will increase, that is, a skill will appear, and the amount of smoke will decrease. But the wire will be irradiated perfectly. Next, as usual, twist the wires and also solder them with a small amount of solder.

The remains of rosin on the soldered twist of wires are washed off with a brush with alcohol. The disadvantage of this method is the impossibility of soldering in hard-to-reach places. For such cases, it is better to use other methods of safe aluminum-copper bonding.

Aluminum is a material with good strength, high thermal and electrical conductivity. These positive qualities contribute to widespread use of metal in industry and life. Quite often there is a need to connect aluminum parts or close up the resulting hole in an aluminum container. But not everyone knows how to solder aluminum at home.

Aluminum soldering

One of the most well-known methods of joining metals, especially in electrical work, is soldering. It provides less resistance to connections, and, as a result, their less heating under the influence of electric current. Because the aluminum along with copper- the main conductive material in electrical networks and devices, the need for its soldering arises quite often.

The difficulty is that the "winged metal" in the air is instantly covered with an oxide film, to which the molten solder does not stick. It is necessary to remove the oxide layer by mechanical cleaning, but it almost instantly forms again.

In order to avoid the re-formation of the oxide film, many techniques have been developed. Among them:

1. Cleaning small parts under a layer of liquid flux.
2. The use of fluxes in conjunction with abrasive materials.
3. Using copper sulphate to create a copper film on an aluminum product.
4. The use of special fluxes and solders.

Stripping under a layer of flux

Small aluminum parts, such as conductors, can be stripped by immersing part of the part in a liquid flux, which can be a common rosin solution or soldering acid. Liquid flux will protect the cleaned area from contact with oxygen and film formation. Ordinary transformer oil has the same protective effect.

Abrasives

Often, iron filings are added to the flux (the same rosin). In the process of soldering, it is necessary to rub the heated place with a soldering iron tip. Under the action of friction, the sawdust peels off the oxide layer, and the rosin blocks the access of oxygen to the released metal. Instead of sawdust, any crumbling abrasive can be used: sandpaper or even a brick.

The use of copper sulfate

A curious method using electroplating. Two aluminum electrodes are lowered into a solution of copper sulfate and connected to the poles of an electric battery. The electrode connected to the plus is cleaned. As a result of electrolysis, copper begins to precipitate on the cleaned surface. When aluminum is completely covered with a copper film, the part is dried. After that, soldering is much easier, because copper is an excellent material for this type of connection.

Special solders

The highest quality connection at home can be obtained using low-melting solders based on tin and copper and special fluxes. The most popular domestic flux is F64, which allows you to solder aluminum parts without mechanical cleaning. So, for example, soldering aluminum with copper is carried out without problems, or an aluminum tube is soldered from the inside, which cannot be cleaned in other ways.

In this case, ordinary low-melting tin-lead solders with a melting point of 200-350 degrees are used. The soldering iron must be quite powerful - from 100 W and above. The reason is the high thermal conductivity of aluminum. An insufficiently powerful soldering iron simply will not be able to heat the soldering point to the melting temperature of the solder. Only very small details(mainly in radio electronics) can be connected with a 60 W soldering iron.

A soldering iron is not suitable for soldering large aluminum parts. Here it is better to use any gas burner that provides heating up to 500-600 degrees, and one of the specialized solders. One of the most popular is HTS-2000, a flux-free solder for aluminum, copper, zinc and even titanium.

He has several advantages:

1. Low melting point (390 degrees Celsius).
2. Can be used without flux.
3. Reliability of the connection (in many cases it can replace argon welding).

True, the HTS-2000 does not exclude the stripping process. Moreover, during the soldering process, it is necessary to peel off the oxide film with a solder rod or a metal brush to ensure a reliable connection. However, this method allows you to perform such work as soldering leaky aluminum containers, such as canisters, or even automotive aluminum radiators.

In addition, HTS-2000 is practically the only (with the exception of argon) method of joining two "winged" metals: aluminum and titanium.

There are other high temperature solders designed specifically for aluminum brazing. For example, 34A, which contains two-thirds of aluminum, as well as copper and silicon. But the melting point of such solders is 500-600 degrees Celsius, which is close to the melting point of aluminum itself.

Therefore, the use of high-temperature solders at home is dangerous - an aluminum part, when heated to such high temperatures, can be irreparably damaged.