Aluminum is a special metal that requires special knowledge to solder. A very strong oxide film is easily formed on its surface, which melts at high temperatures.
The metal itself melts at 660 degrees, but for alloys this figure can drop to 500 ℃. When soldering, there is a danger of overheating the aluminum product, in which case it loses its strength.
The additional complexity of the process is due to the low ability of aluminum to mutual dissolution. The resulting connection may not have the required strength characteristics. A well-chosen flux for aluminum brazing can provide a good result. Mostly active brands are used.
Soldering aluminum skills will come in handy when repairing wiring, electrical equipment, some household items and small homemade structures.
The process must be carried out in several stages. First, the surface is washed, wiped, cleaned if necessary. Then the defects are leveled by grinding. In this case, you need to reach the layer of the metal itself. After a short pause, the flux can be applied. Then the surface is heated.
It should be noted that aluminum has good thermal conductivity. It will cool down quickly.
The dimensions of the heating device must correspond to the dimensions of the soldering zone. Convenient to use soldering irons with adjustable heating temperature. Immediately before soldering, place the solder in the joint. This will further prevent oxidation reactions.
For medium to low temperatures
There are a large number of ready-made compositions for working with aluminum products. Most of them have the letter A in the marking, indicating their purpose. Fluxes can be liquid, greasy, gel-like or solid.
A similar composition is found in FTBF-A, which is more concentrated than the previous analogue. The mass fraction of cadmium borfluoride varies from 9 to 11%; zinc - from 2.5 to 3.5%; ammonium - from 4.5 to 5.5%. The rest is triethanolamine. Work with such a flux is carried out at temperatures from 270 to 350 ° C.
The composition of the F-61A agent is somewhat different. It contains zinc and ammonium fluoroborates, and triethanolamine is the predominant component. The flux is recommended for melting the working zone in the temperature range from 150 to 320 ° C.
The tool can be used when working with a thermoregulated soldering iron, carrying out induction heating... It is permissible to immerse the part in the solder, which must first be melted.
For insulation, fluxes of several compositions are used:
- zinc tetrafluoroborate and triethanolamine;
- aniline fluoride and rosin;
- triethanolamine, cadmium fluoroborate, ammonium fluoride, rosin.
The first of them is used at a temperature not exceeding 350 ℃; the second - 250 ℃; third - 150 ℃.
For brazing aluminum with copper, galvanized iron, some bronzes, a flux is used from two components dissolved in ethyl alcohol: triethanolamine and salicylic acid.
Soldering aluminum products can be made with compounds containing higher organic acids. Known mixture of titanium iodide, rosin and nylon acid.
A flux is used, composed of rosin, bismuth bromide and alcohol; titanium iodide, rosin, caproic acid. The temperature for using such compositions does not exceed 450 ° C.
Features of the high-temperature process
Active flux marked F-34A is popular. It contains sodium fluoride, lithium, potassium and zinc chlorides.
The flux can be used for brazing aluminum and its alloys, in which the magnesium content does not exceed 15%.
The process is carried out at 420-620 ° C. For uniform melting of the mass, careful heating must be carried out, given the high heat transfer of aluminum. At the end of the soldering, the joint should be thoroughly rinsed with water.
If it is necessary to solder aluminum in a high temperature range, the process is carried out by local heating or immersion in baths. In practice, the effectiveness was confirmed by fluxes based on lithium and potassium chlorides, to which sodium chloride and potassium or aluminum fluoride are sometimes added. The mixtures have good fluidity, provide a strong connection at the soldering point.
At temperatures reaching 600 ℃, it is recommended to use a mixture of zinc chloride and copper as a flux. Substances tend to initiate corrosion. Therefore, the remains of the flux are first washed with soda solutions, and then with water.
At present, aluminum and its alloys are widely used in electrical household appliances, such as aluminum electrical wires, etc. Since aluminum and its alloys, in contact with air, quickly oxidize, conventional soldering methods do not give satisfactory results. Various methods of soldering aluminum at home with tin-lead solders POS-61, POS-50, POS-90 are described below.
1. For soldering two aluminum wires, they are pre-tinned. To do this, the end of the wire is covered with rosin, put on a sanding paper (with medium grain) and pressed against the sanding paper with a hot tinned soldering iron, while the soldering iron is not taken away from the wire and rosin is added to the deserved end all the time. The wire is tinned well, but all operations have to be repeated many times. Then soldering proceeds as usual. top scores obtained by using mineral oil for sewing machines or alkaline oil (for cleaning weapons after shooting) instead of rosin.
2. Soldering of sheet aluminum or its alloys is carried out as follows: rosin with small iron filings is applied to the seam with a hot soldering iron. The soldering iron is tinned, and they begin to wipe the seam with it, adding solder all the time. The sawdust with its sharp edges removes the oxide from the surface, and the tin adheres firmly 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 point must be warmed up with a soldering iron and only after that apply flux and solder. Mineral oil can also be successfully used here as a flux.
3. An original way of soldering aluminum wires and an aluminum surface. Before brazing, the aluminum surface of the aluminum part is pre-copper plated using the simplest plating machine described earlier. But you can make it easier.
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Rice. 1
For this, a thick brush for watercolors is taken, and its metal rim, touching the hairs, is wrapped with a bare copper wire (Fig. 1). The other end of the wire connects to the positive pole of the DC source (rectifier, flashlight battery, or rechargeable battery). The aluminum piece is connected to the negative pole. The place of soldering is cleaned with a sandpaper. When starting to cover the part, the brush must be thoroughly moistened in a saturated solution of copper sulfate, and driven 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, for the soldering of mounting elements made of aluminum and its alloys, as well as their connection with copper and other metals, brazing alloys of the P150A, P250A and P300A brands are used. Soldering is carried out with an ordinary soldering iron, the tip of which is heated to a temperature of 350 ° C, using a flux, which is a mixture of oleic acid and lithium iodide.
<<<Назад*
- Tinning stages
- Tinning aluminum wires
To obtain a reliable connection when soldering with tin-lead solder, it is necessary to strip and irradiate the wires.
If we neglect these actions, then it is unlikely that the spike will turn out to be of high quality and durable.
First of all, you should prepare a soldering iron, if necessary, carry out its maintenance: remove scale with a knife, clean the soldering iron tip on a fine-grained emery wheel or using a file.
Before starting soldering, the soldering iron must be warmed up to operating temperature. Then you should dip the sting into rosin, touch hard tin or tin-lead
If a thin shiny layer of solder (and not a hanging drop) has formed on the tip of the soldering iron, you can proceed to further work.
All metals in the air are oxidized. Their surface is covered with an oxide film, which prevents the molten solder from wetting the metal. Therefore, all surfaces to be soldered must be cleaned to a metallic sheen with a knife or fine sandpaper; additionally, it can be degreased with solvents.
With a soldering iron, you need to warm up the wire, apply rosin on it, rub the 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 an 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, then the aluminum in the air is almost instantly oxidized and the film is reduced. But, with patience, you can get a fairly high-quality solder.
- prepare a 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 place of soldering with metal filings;
- Carefully perform the tinning 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 need to be poured into the place of the adhesion.
This method does not always guarantee the achievement of the desired result. Contact between soldered wires can be poor and short-lived.
Professionals prefer to use special solders and fluxes. In this case, the wire to be brazed should not be warmed up 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 easy 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 constant current source with a power of at least 10 watts. A few drops of copper sulfate are applied to the stripped aluminum at the soldering point and wrapped around it with several turns of copper wire.
An aluminum conductor is connected to the negative pole of the current source, and the copper one to the positive. An electric current arises in the circuit, electrolysis occurs, the aluminum conductor is covered with a thin layer of copper. A copper-tinned layer forms on the aluminum conductor. This method cannot be used for tinning massive parts, but it is quite suitable for soldering thin conductors.
If there is no copper sulfate, it can be replaced with hydrochloric acid.
In the place of the proposed soldering, you need to move the copper conductor with pressure. In this case, electrolysis proceeds more efficiently. But it must be remembered that the place of soldering with the use of acid oxidizes over time, therefore, after the end of the work, it must be rinsed with clean water or a weak alkali solution.
Leather - Aluminum
The aluminum mold is not used to facilitate soldering and is produced after zinc processing of the product and.
For soldering and tinning aluminum, use an ultrasonic soldering iron.
Aluminum in air is known to quickly become covered with a layer of oxide film, which prevents the solder from sticking to the metal. Under the action of ultrasound, the oxide film is destroyed and removed from the aluminum surface.
It is especially difficult to harden aluminum. The ultrasonic quenching used for soldering narrow seams is not suitable for thinning large surfaces such as aluminum busbars.
At the Dynamo plant, they developed a method of abrasive and abrasive crystalline parts of an aluminum tire.
Aluminum is especially difficult to clean. The ultrasonic hardening used for soldering with narrow gauges is not suitable for thinning large surfaces of aluminum busbars.
Aluminum is especially difficult to clean.
The ultrasonic hardening used for soldering with narrow gauges is not suitable for thinning large surfaces of aluminum busbars. At the Dynamo plant, they developed a method of abrasive and abrasive crystalline parts of an aluminum tire.
In addition to ultrasonic soldering machines, abrasive solvents are used to abrade aluminum. Unlike conventional soldering irons, abrasive grinding parts 5 (Fig.
68), pressed from solder powder and asbestos, which acts as an abrasive.
Problems in brazing, welding and milling aluminum and its alloys, due to the presence of an extremely stable oxide film on their surface, can be easily eliminated with ultrasound.
In addition to ultrasonic soldering machines, abrasive solvents are used to abrade 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 aforementioned potassium aluminum methods is the use of ultrasound.
Ultrasonic brazing is used for brazing and tinning aluminum.
Rubric: "Working with metal"
Aluminum in the air quickly becomes covered with an oxide layer that prevents the solder from sticking to the metal. Under the action of ultrasound, the oxide film is crushed and removed from the surface, whereby the solder is exposed to access the aluminum surface.
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Soldering any metal parts at home is a simple matter, many boys, especially keen on radio engineering, easily cope with this. For soldering, or tinning, you need a soldering iron itself (the most primitive, requiring heating at a heat source or more advanced - with an adjustable temperature), solder, flux and rosin.
Parts prepared for soldering are cleaned and degreased with sandpaper, gasoline or solvents.
Then a flux is applied to the surface, which prevents oxidation processes on the parts to be soldered.
Using a soldering iron, the tip of which is preliminarily dipped into rosin, solder is applied to the place of the soldering.
How to solder aluminum yourself
However, not everything is so simple - some metals and alloys are difficult to solder.
How to solder aluminum? The difficulty is that aluminum alloys are oxidized in air in fractions of a second, forming films that make soldering by conventional methods impossible.
However, there is a method that allows you to solder aluminum surfaces using the most common soldering iron, solder and rosin.
Soldering aluminum will require a sufficiently powerful soldering iron (60-100 W), since this metal has very good thermal conductivity.
It may be necessary to additionally warm up the parts to be soldered over a gas stove flame.
The secret is that the place of the adhesion is rubbed with bricks, sand, mortar and immediately filled with rosin.
We wipe the parts to be soldered with a soldering iron tip, removing the oxide film.
As a result, a very strong connection is obtained without special costs.
Solder for aluminum, consisting of tin and zinc (tin and bismuth), together with a paraffin and stearin flux, also gives a good result if the solder is protected from oxidation with rosin.
How to solder aluminum when it comes to wires? In this case, you can probably do without soldering at all: for example, use a terminal block.
If you need to connect wires in a confined space, where is the terminal strip or similar connector not possible to fit?
Then it is better to just twist (wind the wire one to the other) and solder to squeeze with pliers.
Active flux for brazing aluminum, based on phosphoric acid, is readily available today.
You can buy it at any store that sells all kinds of radio - and electronic parts and accessories.
This is probably the easiest and most effective way to solder aluminum.
More on the topic:
The composition of fluxes for high-temperature brazing is given in the corresponding section.
The table shows the composition, temperature ranges of activity and the purpose of some fluxes developed from 1973 to 1984. Among organic acids and other substances suitable as an activator of fluxes for brazing aluminum and its alloys at a temperature<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, coprinic, caprylic, nylon, valeric, butyric, propionic, acetic, formic. The activity of these acids increases with an increase in their relative molecular weight and melting point. When they interact with Al2O3 oxide, the following reactions occur:
Al2O3 + 6RCOOH → 2 (RCOO) 3Al + 3H2O (1)
2Al + 6RCOOH → (RCOO) 3Al + ЗН2 (2)
The reaction proceeds most vigorously with formic and acetic acids, less vigorously with caproic acid.
However, the introduction of these acids into fluxes is not very promising due to their intense boiling off at the soldering temperature and a decrease in the breaking energy of the СОО-НС bond - with an increase in the 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.
| Flux brand or number | Flux composition,% | Temperature activity interval, ° С |
Note |
| 1 |
4-7 ammonium borofluoride; 4-7 cadmium borofluoride; epoxy resin rest |
<450 |
For brazing aluminum and Al alloy - 2% Mg (AMg2). High corrosion resistance |
| Form 59A |
10 ± 0.5 cadmium fluoroborate; 2.5 ± 0.5 zinc fluoroborate; 5 ± 0.5 ammonium fluoroborate; 82 ± 1 triethanolamine |
150-320 |
For brazing aluminum or alloy AMts with copper and steel with solders based on: Sn - Zn, |
| Form 61A |
10 zinc fluoroborate; 8 ammonium fluoroborate; 82 triethanolamine |
150-320 |
For brazing aluminum, beryllium bronze, galvanized iron, copper with solders based on Sn - Zn, Zn - Cd |
| Form 54A |
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 flux F54A |
| 4 | <350 |
For tinning aluminum alloys, slightly corrosive-active |
|
| 5 |
1.5 triethanolamine; 4 salicylic acid; 94.5 ethyl alcohol |
150-320 |
For brazing aluminum with copper, beryllium bronze, zinc-plated iron with solders based on Sn-Zn and Zn-Cd |
| 6 |
30 g of lithium iodide; 200 ml oleic acid |
<450 |
For brazing aluminum |
| 7 |
4.2-10 titanium iodide; 16.8-22 rosin; caproic acid - the rest |
<450 | |
| 8 | <450 | ||
| 9 |
10-15 zinc tetrafluoroborate; triethanolamine balance |
≥350 |
For soldering insulated aluminum wires (increases its stability) For brazing aluminum |
| 10 |
7.5 aniline fluorohydrate; 92.5 rosin |
<250 | |
| 11 |
83 triethanolamine; 9 cadmium fluorine borate; 7 acidic ammonium fluoride; 1 rosin |
> 150 |
Among the dibasic saturated acids, which are stronger than monobasic ones, the first three members of the homologous series of acids (oxalic, malonic, succinic) have no activity during aluminum soldering, which is due to their decarboxylation upon heating.
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 brazing. Halogen-substituted acids have a higher activity in fluxes for brazing aluminum, which is explained by the simultaneous action of both the carboxyl group and the halogen atom on aluminum oxide.
It was found that some solid amino acids are active in fluxes: α-aminopropionic and phenylanitronyl, which provide good spreading of the solder.
Taking into account the physical properties, the degree of toxicity and activity in fluxes among organic acids, the most suitable are higher liquid unsubstituted acids, their solid analogs and amino acids.
The fluxing ability of acid mixtures in any ratio does not exceed the activity of the component with the highest molecular weight.
Salicylamide and urea are equivalent in activity to the action of nylon or elaidic acid.
Adding salts to acid solutions
The activity of ammonium salts of organic acids is close to the activity of the starting mono- and diacid 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 galloid 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 salts into acidic fluxing solutions deactivates them due to the displacement of water by the reaction:
Al (OR) 3 + 3H2O → Al (OH) 3 + 3ROH.
However, the presence of water of crystallization in an alcoholic solution of tin chloride does not affect its activity during soldering.
Reactive organic fluxes
Reactive organic fluxes have been proposed for brazing aluminum with low-melting alloys.
The basis of these fluxes is the organic amino alcohol triethanolamine, and the activators are heavy metal and ammonium fluoroborates. At the points of contact of fluoroborates with aluminum, metals: cadmium and zinc are precipitated through discontinuities in the Al2O3 oxide film. Residues of triethanolamine during heating pass into an inert resinous substance that does not cause corrosion of soldered 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 their corrosivity when brazing aluminum, but when brazing 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 overlap soldering with solder stacking at the gap of wrought alloys AMg, D1, D16, V95 and cast aluminum alloys. They can be used only when tinning the brazed aluminum surface with subsequent brazing, for example, with LTI-120 flux.
In this case, the temperature between the parts to be soldered 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. acid, and as an activator bismuth chloride, flux F54A provides a large spreading area of the P250A solder over AD1 aluminum; but it is less active when brazing 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.
For this, thermoregulatory electric soldering irons, induction heating, and soldering by immersion in molten solder are used. Soldering with these fluxes when heated with an open flame is unacceptable due to the possibility of their combustion. At temperatures above 350 ° C, non-propane forms in the soldered joints of contacting joints made with these fluxes. With rapid heating (electrocontact, induction) in pure argon, soldering with these fluxes is possible at a temperature of 320 ° C.
There is evidence of the use of low-melting solder Sn - (8-15)% Zn- (2-5)% Pb with a melting temperature of 190 ° C for brazing aluminum alloys with a flux in the form of a solution of boron-fluoride and ammonium fluoride in monoethanolamine.
In fluxes for low-temperature brazing 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 the brazed seams from oxidation. Carboxylic acids are used as the flux activator. Soldered joints (P250 solder) are not destroyed in a saline solution for 200 days. Wire solder (Sn-Pb-Ag) with a core of the specified flux is suitable for brazing all aluminum materials, which contain less than 3% Mg and 3% Si.
Craftsmen have no problem 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 covered with a film.
Despite the problems we face, aluminum products can be soldered. There are several ways to solder aluminum.
Brazing aluminum alloys
Excellent results can be obtained with the following alloys:
- two pieces of zinc and eight pieces of tin
- one piece of copper and 99 pieces of tin
- one piece of bismuth and 30 pieces of tin
Before brazing, both the alloy and the part must be well heated.
It should also be remembered that soldering acid should be used in this soldering method.
Aluminum brazing with special currents
Standard currents do not dissolve the oxide film on the aluminum surface, therefore special active currents must be used.
Aluminum soldering flux is used to work with pliers with an operating temperature of 250-360 degrees. This flow, during brazing and hardening, cleans 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. The excess of this flow can be easily removed with solvents, alcohol or special fluids.
Other ways of brazing aluminum
There are also non-standard ways to solve this problem, for example:
- Thoroughly clean aluminum parts from the soldering iron 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, connect to the battery plus terminal for 4.5 volts. Part of the wire with the rolling circle falls on a small amount of copper sulphate. 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 into this room, you can usually weld the necessary parts or wires.
- In this case, use an 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 will cook well and apply these spots until the tin layer is separated on the surfaces. Then rinse the parts and then solder in the usual way.
- This method requires a transformer.
Its minus is connected with the product, and a copper wire of a large part, consisting of small vessels, is connected to the connection. If you connect this wire to a future soldering point within a short time, a copper and aluminum micro-solder will be made, which in the future will allow the wire to be connected in the usual way.
To simplify the process, you can use soldering acid.
Soldering aluminum cookware (without soldering iron)
Some household needs use aluminum accessories, sometimes breaks and don't buy a new one (which is very expensive), you can fix these products by soldering without a soldering iron.
The next method is suitable for sealing small holes (up to 7 mm in diameter).
- The soldering point should be cleaned with a metallic sheen using sanding paper or a file. If the containers are enamelled, the holes around the enamel must be removed within a radius of 5 millimeters.
For this, the light touches the hammer from the 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 stove fire.
If the containers are enamelled, it is preferable to heat them over a light bulb - this allows the place to be heated more, so other sponges do not heat up.
- When heated, the mucus melts and closes the hole in the pot.
At the same time, no soldering iron is needed.
Aluminum is highly durable, a good conductor of heat and electricity. It has a low specific gravity, is easy to handle, and is environmentally friendly. However, all these positive qualities create almost insurmountable obstacles when solving the problem of how to solder aluminum at home with a soldering iron. This cannot be done using traditional methods, so you have to use special welding methods and optimally selected materials.
Technical difficulties in soldering aluminum products and parts
Soldering aluminum structures and other elements is always quite difficult, especially if it is done at home by novice craftsmen who have not fully studied the process. Basically, such soldering is carried out by industrial methods on special equipment. However, it is quite possible to create the most suitable conditions for welding parts made of aluminum.
To achieve this goal, it is imperative to resolve several technical problems:
- Most of the troubles in soldering are caused by oxidation in the form of a film that appears on the surface as a result of contact between aluminum and air. Even if the metal is prepared, plaque forms on it almost immediately afterwards. Such a film coating creates obstacles to the joining process and adds many problems in the tinning and soldering process. In this situation, the usual types are completely unsuitable, since they do not guarantee a good connection. The film is removed either physically and mechanically, or using strong chemicals.
- The high temperatures at which aluminum begins to melt should also be taken into account. It reaches a maximum of 600 0 C. There is a temperature difference between the metal to be soldered and its film, which causes difficulties in the process of soldering.
- Due to the temperature regime, aluminum begins to noticeably lose its strength during heating. This moment comes already when the material to be welded is heated up to 250-300 degrees. Some aluminum alloys contain components whose melting point differs from the base metal.
- Weak interaction of aluminum with traditional types of solders, consisting mainly of tin, cadmium and other elements. This leads to insufficient strength characteristics and reliability of the created seams. The problem of how to solder is solved by means of special solders containing zinc, which, in turn, is in excellent contact with aluminum and penetrates into it. Bonding occurs, reaching the molecular level, providing the necessary bond strength.
Preparation for brazing aluminum parts
Great importance is attached to the preparation of aluminum for the forthcoming brazing.
To do this, there are several ways to ensure the reliability of the connection:
- The joint area is pre-degreased and treated with rosin. After the substance is applied to the surface, an emery cloth is also placed here. Next, you need to turn on a powerful soldering iron and press the sandpaper tightly to the surface.
- After that, the surface is rubbed and sanded, and the junction itself is simultaneously tinned. An aluminum part is installed on the prepared surface, which can be soldered according to the usual scheme. If necessary, the rosin can be replaced with the oil used in sewing machines.
- In the second version, metal shavings are added to the rosin, after which the resulting mixture is applied to the surface of the future joint. The soldering iron tip must be well heated and tinned, and then rubbed with it on the entire working surface of the parts to be soldered until the chips melt. At the same time, solder is added here. In this case, the oxide is removed mechanically, and the solder immediately hits the surface and protects it from the reappearance of the oxide film.
- The third way is to pre-clean the surface. For this purpose, copper is used, through which the oxide film is removed. This method is one of the most difficult, since the copper plating of the surface must be carried out in a special bath.
Selection of solder and flux for aluminum
Solders based on tin and lead can be used for welding wires, elements and parts made of aluminum, provided they are thoroughly cleaned. Such soldering should be carried out using special flux solutions consisting of highly active substances. However, such joints have insufficient strength due to the weak interaction of aluminum products with tin and lead, the tendency to form corrosion. Therefore, in the form of an anti-corrosion coating for surfaces made of this metal, special compounds are used.
Such compositions include solders containing copper, zinc, aluminum and silicon. They are produced both in our country and abroad. Among domestic brands, TsOP-40, the content of which is 40% zinc and 60% tin, as well as compound 34A with aluminum (66%), copper (28%) and silicon (6%), is the most widely used. The zinc content affects not only the strength of aluminum contacts, but also their corrosion resistance.
Of all the known solders, the tin-lead-based compositions have the minimum temperature at which they begin to melt. The highest melting point belongs to compounds with an aluminum-silicon structure, as well as with aluminum, copper and silicon. In the first case, similar types of solders melt when the temperature reaches 590-600 degrees, and in the second - at 530-550 degrees. They are selected for each specific case when parts with large dimensions, with good heat dissipation or refractory aluminum joints are connected.
Technological processes are inextricably linked with special types of fluxes used for better interaction of all welding components.
The selection of the most suitable material is considered a rather difficult undertaking. This is especially important when a tin-lead-based solder is used in the work process. The structure of such fluxes includes elements that form its increased activity when interacting with aluminum. Among them are triethanolamine, ammonium fluoroborate, zinc fluoroborate and other similar components.
One of the most popular fluxing substances of Russian production is considered to be a substance of the F64 brand, which is distinguished by high activity. The quality of this connection allows you to solder metal parts made of aluminum without removing the refractory oxide coating located on the surface.
Soldering aluminum components
The procedure and technical process for welding aluminum is exactly the same as for other types of non-ferrous metals.
Among the home craftsmen, the following two options are most commonly used:
- High temperature brazing, used to weld large size elements. This category includes aluminum structures with thick walls and increased weight, which require a temperature of 550-650 ° C to warm up.
- Soldering at low temperatures of 250-300 0 С, which is quite enough for mounting wires of electronic equipment and welding small items used in everyday life. In the same mode, aluminum wires are connected in any electrical network.
High temperature connections are made using special heating elements. One is a burner that requires propane or butane gas to operate. If such a torch is not available, DIYers use different types of blowtorches. Welding at high temperatures requires constant control over the degree of heating of the surfaces of the parts to be joined. For this, one of the refractory solders is taken in a small amount, and after it begins to melt, we can talk about reaching the desired temperature. In this case, the heating of the part stops, otherwise it will simply melt and collapse.
Soldering at a low temperature is carried out with a 100-200 W electric soldering iron. The power of the soldering iron depends on the size of the components to be connected: the larger the part, the more efficient the soldering iron will be required in order to warm it up. The conductors are easily connected with a 50 W soldering iron.
Regardless of the temperature regime, the connections are performed in the same way, and all actions are performed in the following order:
- The place of the future connection of parts or cables is processed mechanically. For this, any cleaning agents are used that weaken the oxidative plaque, providing a more complete interaction with the flux substance.
- The junction must be degreased with acetone, gasoline, alcohol and other organic solvents.
- Before soldering aluminum with a soldering iron or a torch at home, the parts are firmly fixed in the most comfortable position.
- The flux is applied to the prepared plane. If the substance is used in liquid form, then it is applied with a brush.
- The connection point is heated with an electric soldering iron of sufficient power or with a gas torch. Further, molten solder is applied here and distributed in an even layer.
- Metal surfaces are connected and fixed in position.
- After the solder has cooled and the parts have set, the junction is rinsed with running water. The remaining flux is washed out and does not cause corrosion in the future.
You can solder aluminum. Although wires made of this metal can be easier to connect in other ways: through screw terminal blocks, by welding. Often in junction boxes, aluminum wires were simply twisted tightly. This method was used when a particularly powerful energy consumption was usually not observed in apartments.
But now, with the saturation of the market with powerful and diverse household appliances, the entire household supply network should be brought to such a quality that would be oriented towards serious energy consumption approaching industrial. And in this case, it is better to solder the aluminum at home than to twist it.
Properties of aluminum as a metal and a conductor
Aluminum is on the periodic table right after sodium and magnesium - active, even combustible in air, metals. Therefore, it is a light and very active metal. Its thermal and electrical conductivity is lower than that of copper. But since aluminum is lighter than copper, products made of it, where these properties are important, are geometrically large in size with the same mass. And due to convection, heat dissipation from aluminum parts can be greater than from copper ones.
The activity of aluminum works against soldering, a standard operation for the electrical and mechanical joining of many metals. Because the activity is such that it immediately oxidizes in air. And it is covered with an impenetrable film of corundum - Al 2 O 3. Other aluminum compounds are also very strong, which makes the extraction of this most common metal in the earth's crust energy-intensive: the production of 1 ton of aluminum requires 17 megawatt / hour of electricity.
Only in our country this did not turn out to be an obstacle to large volumes of production and widespread use of this metal.
In addition to aluminum itself, alloys based on it are used - duralumin and silumin.
If pure aluminum is mainly used for electrical engineering, then various products are made from alloys: from silumin - cast things (meat grinders, dishes), persistent structures, from duralumin - frames, body parts, mounting profiles.
Alloys seem to work against the eternal enemy of aluminum shareholders - oxide film - and they should be soldered well. However, the soldering of duralumin and silumin itself violates the valuable properties of these alloys at the joints, which makes the soldering fragile and quickly destroyed.
Therefore, it is necessary to solder aluminum as such, and you can try to solder products from its alloys, but only where special requirements for the mechanical strength of things that are being soldered are not expected.
Work order
The usual brazing steps and means also apply when brazing aluminum. It's just that aluminum is such that it is stricter regarding the choice of components.
Soldering aluminum at home requires:
- A powerful soldering iron (60-100 watts or more) is sufficient. This is due to the heat capacity and thermal conductivity of aluminum. This metal very strongly removes heat from the soldering point.
- Application of additional materials and tools processing the metal surface: emery, file; copper sulfate for tinning; iron or copper fine filings.
- The use of special fluxes, enveloping the metal surface, preventing immediate oxidation by atmospheric oxygen or dissolving the oxide in acid.
- The use of other substances that create a film on the surface (grease, machine oil, brazing fat, technical petroleum jelly, aspirin, stearin).
- Solder based on tin with zinc (8: 2); tin with copper (99: 1); tin with bismuth; POS 40; POS 60; solder for soldering aluminum.
- Mandatory preliminary tinning of the metal surface.
- Thorough subsequent rinsing of the seals in warm water to remove acid and flux residues.
A great variety of fluxes for soldering aluminum are sold - liquid, pasty, pencil, gel: F-34a, F-59A, FTBf-A, F61A, F-63, FTKA, F-64 and others.
Soldered surfaces must be cleaned, processed with a file or emery paper. Then heat up and apply an even layer of flux.
Tinning the metal surface
It is necessary in a hot state under a layer of flux to damage the layer of Al 2 O 3, which after mechanical cleaning had time to form on the aluminum, and at the same time apply a layer of solder. Such damaging elements can be abrasive particles, or thin iron or copper filings, or copper sulfate crystals added to the flux. They should be, without waiting for the drying or burnout of the flux, applying a layer of solder with a soldering iron, rub it with a sting into the surface. When carrying out work in a house or apartment, it must be remembered that the components of fluxes are caustic and toxic, they boil and smoke from heating with a soldering iron. It is necessary to work in a ventilated area.
Soldering
Soldering copper and aluminum is no more difficult than soldering aluminum to copper. Both surfaces must be tinned, copper is exposed to this without much resistance, it is only necessary to clean it and prokanifol before tinning. Copper and aluminum give excellent alloys, as well as soldering aluminum with tin, this presents no other difficulties besides overcoming the oxide film.
The wires, pre-tinned, are twisted into a twist, and it is soldered so that the solder solders the gaps between the wires.
Long objects, such as pipes or tubes, tin flasks, are soldered to aluminum in exactly the same way. If a small part is soldered onto a wide surface with a large heat dissipation (for example, a flask), then the soldered section can be additionally heated on a gas stove or burner.
It is possible to solder small holes according to the following rule: clean the surface, tin, cool a little, put a covering piece of tin or solder on the hole, gently solder this place with a soldering iron or a stream of flame from the burner.
Final processing
So, when are the answers to the questions "how to solder?", "How to solder?", "What to solder?" left behind, the work is done, then before admiring the welded brainchild, you need to do the final finishing. At the same time, the soldered place is cleaned of irregularities, the excess drops of solder are carefully soldered, after cooling, the soldering is slightly checked for strength. After brazing aluminum using materials containing chemical reagents, a good rinsing with water, wiping with a cloth slightly soaked with soda solution, and drying is necessary.
Aluminum soldering technique
Application of flux for brazing aluminum
Aluminum is widely used as a material for a wide variety of structures. It is only slightly inferior to steel in its strength. Aluminum is much easier to process, it has very high electrical and thermal conductivity.
However, there is a serious problem when deciding how to solder aluminum with a soldering iron, since there are specific features and difficulties. The fact is that conventional methods are not suitable for aluminum.
Aluminum soldering technique
Difficulties in soldering aluminum are due to its ability to form oxide films in literally a split second. Therefore, for this operation, soldering irons require special replacement tips or mercury-based fluxes.
While aluminum wires are relatively easy to solder, there are many problems with uncomfortable flat surfaces. To solve them, it is necessary to carry out thorough preparation for work.
The soldering procedure can be performed with an ordinary soldering iron with ordinary solder and rosin. Due to the high thermal conductivity of aluminum, the soldering iron must have an increased power from 60 to 100 watts. If the available soldering iron is not able to warm up large parts, they are additionally warmed up on an electric or gas stove.
Before starting the soldering, the joint is carefully cleaned with a file, crumbling brick or sandpaper. After the thick oxide film has been removed from the surface, it is degreased with gasoline or any organic solvent. After that, the place of soldering is lubricated with flux. At the same time, the soldering iron is immersed in the rosin. The appearance of a slight haze indicates readiness to work. Instead of rosin, ammonia can be used. Thus, the soldering iron tip is cleaned of foreign metal oxides.
The further procedure is practically no different from working with ordinary metals. The cleaned tip of the soldering iron is dipped into the solder and held in it until it is completely covered with a film. After that, a small amount of solder is captured by the sting, transferred to the place of soldering and leveled over the entire surface, pre-tinning it. Then the main amount of solder is applied to ensure a strong aluminum bond. Wait until the solder cools down and then wipe the joint with a damp cloth. The final cleaning is done with a file or sandpaper.
Aluminum soldering flux
Flux plays a special role in the process of soldering aluminum parts. It effectively removes airborne oxide films and grease. In addition, the flux protects the surfaces from oxidation during soldering.
Aluminum soldering flux is sold ready-made, but it is quite possible to prepare it yourself. To prepare the flux: take 30 g of zinc chloride, 10 g of ammonium chloride and dissolve in 60 milliliters of water.
Often, instead of a flux, a so-called brazing liquid or brazing acid is used. It is obtained by reacting concentrated hydrochloric acid with metallic zinc. For this purpose, acid is poured into glass or porcelain dishes. This action must not be performed near an open flame due to the explosive hazard of the hydrogen released. Zinc is added to acid in small portions. As a result of a chemical reaction, zinc chloride is formed. After the hydrogen ceases to evolve, the dishes with the resulting substance are placed in warm water. The finished liquid is mixed with ammonia.
With normal adherence to technology, the strength of the bond is higher than that of many metals.
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How to solder aluminum at home: solder for soldering, methods, features
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 instant appearance of a thin oxide film at the site of stripping, which interferes with the soldering. An additional difficulty is created by the material itself, which has a low temperature threshold for melting (+660 ° C). Using solder for soldering aluminum, special strong fluxes and observing the technology, you can independently solder almost any object made of aluminum.
Features and principles of soldering
The low temperature value of metal melting complicates the technological process of 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, tin, come into hard contact with aluminum and do not provide sufficient strength. Excellent solubility is observed in metal in combination with zinc, which gives the welded joints high reliability.
Before the start of soldering, aluminum elements are well cleaned from oxides and dirt. To do this, you can apply mechanical action with brushes or use special fluxes from a potent composition. Before the procedure itself, it is imperative to tin the areas to be treated. The tin coating will protect the part from the formation of oxides. To reliably solder aluminum products, it is necessary to choose the right heating tool, taking into account the volume of the metal being processed. In addition, the reliability of the connection depends on which alloy is chosen, as well as the flux for brazing aluminum.
Soldering methods
Soldering of aluminum products is carried out with an electric type soldering iron, blowtorch or gas torch. There are three ways to solder a variety of aluminum objects:
- with rosin;
- using solders;
- electrochemical method.
With rosin
This option for soldering aluminum objects, wires, cables is used for small parts. To do this, the cleaned section of the electrical wire is covered with rosin and placed on a piece of sanding paper with an average grain size. From above, the wire is pressed with a tinned tip of a heated soldering iron. This action is carried out several times, after which the procedure for soldering the electrical wires is performed. A rosin solution in diethyl ether can be used.
In this case, the end of the soldering iron is not subtracted from the tinned end, but rosin is added on top. An electric soldering iron with a power of about 50 W is suitable for twisting thin aluminum wires. With an aluminum thickness of about 1 mm, a 100 W soldering iron is required, and parts over 2 mm require preliminary heating of the joint.
With the use of solders
This method is the most common and is used in electrical engineering, when repairing car parts, as well as other products. Before brazing aluminum, a preliminary coating of the place to be sealed with an alloy and subsequent connection of tin-plated elements is carried out. Pre-tinned parts are bonded 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 preserves its strength. Compositions with cadmium and tin do not provide sufficient contact reliability and are subject to corrosive effects. Refractory materials with zinc, copper, and aluminum-based silicon are devoid of these disadvantages.
Electrochemical method
This procedure requires a setup to perform the electroplating. With its help, copper plating of the surface of a product or wire is carried out. In its absence, independent processing of the part is used. To do this, a few drops of a saturated solution of copper sulfate are applied to a place cleaned with a grinding sandpaper. After that, the negative pole of an independent power supply is connected to the workpiece.
They can be a battery, accumulator or any electric rectifier. A stripped copper wire with a diameter of about 1 mm, located in an insulated stand, is connected to the positive terminal. In the process of electrolysis, copper will gradually settle on the part, after which the area is tinned, dried with an electric soldering iron. After that, you can easily solder the tinned place.
Solders, materials, fluxes
Soldering of aluminum with tin is performed 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 weak protection against corrosion processes.
How to solder aluminum elements? High-quality brazed 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 point and provides good corrosion resistance. Imported low temperature alloys with excellent performance include HTS-2000, which provides maximum ease of use.
These alloys are used to work with large-sized parts (radiators, pipes) with a high heat dissipation using a heating pad or objects made of aluminum alloys with a rather high-temperature melting. Novice repairmen can familiarize themselves with the soldering process by watching a training video. This will help to avoid many unpleasant nuances in the process of work.
In addition to solders, aluminum brazing requires the use of special fluxes containing ammonium, 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 preliminary cleaning of products from the oxide film. In addition, 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 using the correct technology, but also from preparatory work. These include the processing of sealed surfaces. It is necessary to remove dirt and thin oxide films.
Mechanical processing is carried out using a sandpaper, a metal brush, stainless steel wire mesh or a sander. In addition, various acidic solutions are used for cleaning.
Surface degreasing is performed using solvents, as well as gasoline or acetone. On the stripped aluminum section, the oxide film appears almost immediately, but its thickness is much lower than the initial 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 versatile tool, quite convenient for soldering wires, repairing small pipes and other elements. They require a minimum of working space, as well as the presence of an electrical network. Repair of large-sized items and welding is performed with a gas torch that uses argon, butane, propane. For soldering aluminum objects at home, you can use a standard blowtorch.
When 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 fire tongue is bright blue. A dull shade, as well as a small flame, indicate an excess of oxygen.
Technological process
The technology of soldering aluminum objects is similar to the process of joining parts of other metallic materials. The first step is to clean and degrease the places of future soldering. Then the connected elements are set in the working position for the convenience of processing. A flux is applied to the prepared area, and, initially cold, the 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 performed in a room with good ventilation, since hazardous compounds are released during operation.
The use of flux-free solder requires observance of some nuances. To prevent the oxide film from interfering with the ingress of the alloy onto the parts, the end of the bar performs scratching movements along the area where the elements are soldered. This violates the oxide integrity and the solder comes into contact with the metal being processed.
The destruction of the oxide layer during brazing can be performed by another method. For this, the area to be treated is scratched with a metal brush or a stainless steel bar.
To ensure maximum strength of the 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.
oxmetall.ru
We solder aluminum
There are situations when it is necessary to solder aluminum products. But due to the fact that the oxide film covers the surface of aluminum, the solder simply does not stick to it. Solders and fluxes have been developed specifically for this purpose. But we will try to cope with this task in the old old-fashioned way. Attention! Work should be done in a well-ventilated area, preferably equipped with active ventilation or outdoors. To solder aluminum, we need machine oil (used to lubricate sewing machines), a small piece of sandpaper, rosin and ordinary solder for soldering radio components.
A soldering iron is needed as powerful as possible. For example, this. Its power is 65 W. 
We will solder the bottom of an aluminum beer can. Before work, the tip of the soldering iron must be leveled with a file (remove all shells) and tinned. 
Use a piece of sandpaper to clean the soldering area until it shines. 
Pour some oil on this place. 
Next, rub the oil stain with sandpaper. 
By this we remove the oxide film, and the oil does not allow the formation of a new film. The soldering iron by this time should be warmed up to operating temperature. Dip the tip of the soldering iron in rosin, collect as much solder as possible, dip it again in rosin and quickly begin to rub the future with little effort. place of soldering. At the same time, the oil begins to burn out profusely. Therefore, we do not regret rosin. If everything was done correctly, then our tin layer should cover the surface of the aluminum. 
Sometimes, to achieve the desired result, you will need to repeat this operation several times. 
Copper wire can be soldered to tinned aluminum very easily. 
Now let's try to tin and solder the aluminum wire. We remove the insulation from it and clean it to a shine. Pour machine oil on the tinned bottom of the can. 
Next, the wire must be dipped in oil and rubbed with sandpaper. 
Then we try to tin the wire right at the bottom of the can. If it worked out, then everything was done correctly. If not, work with sandpaper again. 
The wire is also perfectly soldered to the aluminum can. 
Instead of machine oil, you can use gun oil. If the aluminum part is large, then it may need to be additionally heated. For example, on an electric stove.
sdelaysam-svoimirukami.ru
How to solder aluminum with tin with your own hands
How to solder aluminum at home
Soldering wire connections with solder is considered the most reliable method for connecting wires and cable cores. It is good if you only need to solder copper wires, which are easily tinned with solder. It is not for nothing that in electronics all the outputs of the elements are copper, tinned.
Soldering aluminum at home
After the solid wires and stranded conductors of the cables are irradiated, it is quite easy to connect them 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 upon contact with oxygen. In order for the solder to adhere well to the aluminum wire, you need to remove the alumina and then tin.
For this purpose, there exist as a flux: soldering acid, special fluxes for aluminum, a mixture of rosin with acetone. All these advantages destroy or hinder the formation of an oxide film on aluminum. After using this type of flux, the aluminum tinning process is simplified.
The necessary tools for soldering aluminum with tin are: an electric soldering iron, a sharp knife, wire twisting pliers, a fine file to prepare the soldering iron tip. Of the materials required: POS 61 or POS 50 solder, flux for soldering aluminum F-64 or similar, a sponge.
Soldering aluminum with tin and flux Ф 64
Flux Ф 64 is intended for aluminum soldering. The soldering technique is not complicated. 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. Cut 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 the gumboil. Thus, the aluminum oxide film of the wire is removed, preventing it from being oxidized again in air. Then, with a heated soldering iron with solder, they begin 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 tinned with a soldering iron, moving back and forth, at the same time the oxide film is removed from the aluminum. It will not be possible to trick the wire exactly right away. Therefore, flux is again applied to the non-tinned sections of the wire, and the sections of the remaining oxide film are removed with a hot soldering iron with solder and movements back and forth and are serviced.
Thus, the aluminum wire is completely covered with solder. After tinning, the aluminum wire is dipped in 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 remaining flux must be washed off. It will not be possible to completely wash it off, since it partially remains under the solder and eats into the wire.
But at least partially it needs to be washed off. Copper wire is not served with F 64 flux, it is better to use a solution of rosin and alcohol (50% to 50%). With a brush, apply liquid rosin to the copper wire (after having previously stripped it) and serve the wire with a hot soldering iron, starting from the end. The tip of the soldering iron must be straight and clean. The shells at the end of the soldering iron tip are removed with a small file.
And the remnants of burnt solder (slag) are wiped off 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 joint is soldered, starting also from the end. If you connect aluminum without tinning with solder, then this connection can be broken over time. The connection of aluminum with copper is a galvanic pair, and when current passes through it, it heats up and destroys the connection.
Table of temperature regimes of grades of solder
As a result, the twisting place gets very hot and charred, which increases the fire hazard. Tin solder is neutral to aluminum, so aluminum wires must be tinned before being connected to copper. For soldering aluminum wires, POS 61 and POS 50 solder with a low melting point of 190 - 210C are well suited.
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 brazing. As a result, the junction of the wires is corroded by acid over time, oxides are formed, which heat up when current flows and can cause a fire in the insulation. These acid-containing fluxes include special fluxes for aluminum soldering, 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 select a low bath for liquid rosin (60% rosin and 40% alcohol).
Soldering fluxes for aluminum
The bath is filled 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) remove the oxide film from the aluminum wire without removing it from the bath. That is, under the rosin, the wire is protected 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 preheated soldering iron with solder with a power of at least 60 W and lower it onto a bare and oxide-free wire, at the very surface of the rosin, 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 the liquid rosin. So that the stripped sections of the wire from the oxide could not come into contact with air.
The soldering iron can be immersed at times 2-3 mm in rosin. After slightly irradiating the wire, lift 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 to solder outdoors or in a room with good ventilation. After several attempts, you will have developed your own tinning technique and a little experience.
You will determine 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 tinned perfectly. Next, as usual, twist the wires and also solder them with a small amount of solder.
The remnants of rosin on the soldered wire twist 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 safely connecting aluminum to copper.
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