✅ How to solder copper and aluminum in a refrigerator

Even in specialized forums and online communities, professional electricians cannot come to a consensus on a simple and effective way to connect copper and aluminum in household wiring.

What can we say about the ordinary home craftsman who encounters electricity from time to time. It is for such beginners that I review six popular methods of creating reliable electrical contact, showing their differences.

All you have to do is read the article on the site and choose for yourself the method that requires less effort and is easier to perform in order to ensure high electrical safety.

Soldering aluminum to copper

Author:
Igor

Date of:

08.07.2016

Article
Photo
Video

Soldering aluminum has always been a rather complex technological process, since its melting point is considered relatively low, and the properties of the connection are not at the highest level. Soldering aluminum with copper becomes an even more complex and problematic process, since copper is difficult to melt, although it can be soldered normally. Despite the complexity of the process, there is a need for it periodically in various industrial areas and even in the home environment. Under normal conditions, without any additional means and with standard materials, it will be almost impossible to obtain a high-quality connection without damaging the metal of the workpiece.

DIY aluminum and copper soldering

Soldering copper and aluminum requires a special approach, since even standard solder for soldering aluminum will be ineffective. It is worth noting right away that with aluminum there is a greater conflict with copper, since the soldering process with steel is better. Many craftsmen use this when creating complex connections. The need for such soldering arises both when connecting pipes or other large parts, and when connecting wires, which from the technical side is easier, simpler and faster, since there are no large loads on the final product.

DIY aluminum and copper soldering at home

How to prepare parts for soldering?

Before you start soldering with your own hands, part of the part must be properly prepared. The surface of the material should be degreased.

To do this, you can use gasoline, acetone, or any other solvent. To remove the oxide film, you need to apply physical force.

To do this, you can use various materials: stainless steel mesh, brush, abrasive wheels.

To remove the oxide film, you can use acids; this method is labor-intensive enough to be used at home.

After treating the metal surface using a stainless steel product, the old film will be removed, but a new one will form in its place.

It will be weaker and thinner. The flux will dissolve it much faster than the one that was previously removed. Surfaces made of brass and copper are much easier to clean.

Video:

Before soldering one part to another, it is worth heating them up. If steel objects are large, you should use a blowtorch or special gas burners for heating.

When heating with a burner, you need to be careful and monitor the operation of the burner at all times. The base material should not overheat, as it will melt and lose its shape.

Constant monitoring of the burner temperature is necessary. To do this, the solder rod must be briefly applied to the surface. When the temperature reaches operating temperature, the solder will melt.

It is worth paying attention to the burner flame that heats the parts.

The gas compositions of the mixture for the burner must be balanced and not have a lack/excess of oxygen.

If there is more oxygen than normal, the metal surface will oxidize. A similar situation will not happen if you work with surfaces made of steel, brass, and copper.

When working with small parts, burners are not used; soldering irons powered by mains power are usually used.

If multiple components need to be connected, wave soldering is used. The video shows how to work with soft and hard solders.

How to remove oxide film

The film is removed from the metal surface in several ways, the most effective being chemical and mechanical. Both methods require an airless environment in which there is no oxygen to work.

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The chemical method is based on the deposition of zinc or copper on the surface of the workpiece by electrolysis. Copper sulfate in the form of a concentrated solution is applied to the area prepared for soldering. The negative terminal of a battery or other power source is attached to a clean area of metal. One end of the copper wire is connected to the positive terminal, the other is dipped into a solution on the surface of the aluminum. As a result of electrolysis, copper or zinc is deposited in a thin layer on the aluminum and adheres tightly to it. Now you can solder aluminum with tin.

An oil film is used to remove the oxide. For this method, it is better to use synthetic or transformer oil with a low water content. Other types of oils need to be kept at a temperature of +150...+200°C, the water will evaporate. At higher temperatures, the contents will begin to splatter. Dehydrated oil is applied to the surface of the aluminum part. Use sandpaper to rub the aluminum under the applied layer to remove the oxide.

The emery cloth is replaced with a scalpel, a serrated soldering iron tip, or iron filings obtained from a nail rubbed with a file. The shavings are poured onto the oil and the soldering iron tip is rubbed over the surface, removing the oxide layer. It is advisable to heat a massive part with a hot air stream. The solder is dipped into the oil droplet with a soldering iron and rubbed over the soldering area. To improve the soldering process, rosin or other flux is added.

For soldering aluminum wires, fluxes based on acetylsalicylic or orthophosphoric acid, boric or sodium salts have been created. Rosin is rarely used; it is ineffective in the case of aluminum. Fluxes are used when soldering wires, pots and other things.

Wire soldering technique

Remove the insulation to the desired length, usually 3-5 cm.
If necessary, clean and degrease the wires (depending on the type of wire).
Twist the wires tightly together.
Cover the soldering area with flux.
Place solder on the tip and solder the twist. It is important to heat the wires evenly so that the solder covers all surfaces and fills the cavities.
Insulate the resulting connection using heat shrink tubing (must be put on before soldering) or regular electrical tape.

There are different ways to connect and solder wires. They don't always have to be twisted. If the wires are soft, for example made of copper, it is better to twist them to ensure reliable contact.

If the wires are hard and brittle, they can be placed next to each other and then soldered without twisting. This will eliminate the risk of fracture during twisting.

When soldering without twisting, it is highly recommended to pre-tin both wires. Instructions on how to tin wires with a soldering iron:

Strip each wire of insulation.
If necessary, remove the varnish from the wires. This is best done with a sharp knife or sandpaper.
Treat the core with flux.
Apply molten solder evenly to the surface using a soldering iron.

A properly tinned wire should be completely covered with a layer of solder. Next, these wires are twisted or tightly applied to each other and soldered. You don't need to use a lot of solder, since each of the wires is already coated with it.

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 stripping. So, for example, soldering aluminum to copper can be done without problems, or an aluminum tube can be sealed from the inside, which cannot be cleaned by any other means. Article on the topic: How to find out what kind of freon is in the refrigerator

In this case, conventional low-melting tin-lead solders with a melting point of 200−350 degrees are used. The soldering iron should 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 area to the melting temperature of the solder. Only very small parts (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 soldering aluminum, copper, zinc and even titanium.

It has several advantages:

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

True, HTS-2000 does not exclude the stripping process. Moreover, during the soldering process it is necessary to remove the oxide film with a solder rod or a wire brush to ensure a reliable connection. However, this method allows you to perform such work as sealing leaky aluminum containers, for example, cans, or even car aluminum radiators.

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

There are other high temperature solders designed specifically for aluminum soldering. For example, 34A, which contains two-thirds 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, using high-temperature solders at home is dangerous - an aluminum part can be irreparably damaged when heated to such high temperatures.

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We solder aluminum and copper with a regular torch.

Price: $12.15

Go to the store

Characteristics.

Diameter: 2.0 mm, length: 500 mm Soft solder ISO 3677:

B-Zn98Al 381-400 Approximate composition (weight%): 2.4 Al – rest Zn Melting point ºС: 430-440 Operating temperature ºС: 440 Tensile strength (MPa): Up to 100 (Al) Density (g/cm3) : 7.0

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Unpacking and appearance.

White package

Inside is a zip bag with wire and instructions. Diameter 2 mm, length 3 meters. Slightly stiffer than aluminum rod of the same diameter. It is made in the form of a tube, in the center of which you can see the flux. When bent repeatedly, it breaks lengthwise. The instructions are simple - heat the surface and rub it with solder.

Let's move on to practice.

First, I checked the melting point. At 360 ºС it softens, but is not very fluid, but at 400 it melts like tin, so the melting point is really lower than that of Castolin 192FBK.

Next, let's take an aluminum tube, cut off a piece and try to partially solder it. And something goes wrong. The solder forms balls and rolls over the surface. I've seen a lot of angry reviews from people who got a similar result, saying it's easier to melt a part than to solder a gap in it. But you need to understand that although flux protects against oxidation, it does not remove the long-term oxide film, so it is necessary to clean the surface, after which the process goes like clockwork. Due to the flux, the surface becomes cloudy. I rubbed it a little with a brush. Pretty good, you can remove the excess if you want. The part warmed up well, but the solder leaked from the inside of the joint. We are testing. During normal welding, rupture should not occur along the seam, and this is what happened Larger on the right and on the left. Here you can see that the tube began to tear above the seam. In addition to aluminum, copper can also be soldered. It has higher thermal conductivity, so the process goes much faster. The appearance is spoiled a little by the cloudy film, but it is easily removed. It leaked just as well from below. But the connection is not as strong as when working with aluminum. Not without difficulty, but they managed to tear off the tube, and you can see that the top layer was torn off, as if the solder had eaten into a tenth of a millimeter. I even thought that the tube was coated with copper, but I rubbed the surface with a brush and it again acquired a copper shine.

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Results.

I ordered this item just out of interest, but the experience turned out to be interesting.

The melting point is almost half the melting point of aluminum, so the temperature of a conventional gas burner is sufficient for operation and the risk of melting the part is minimized. The seam turns out to be quite strong, so this is a good alternative to argon welding, especially if there are no other options, and you need the result right now. Solder also covers the surface well, which makes it easy to eliminate ruptures in tubes made of non-ferrous metals and radiators in cars and refrigeration equipment. True, I do not have the opportunity to test this under high pressure, but the copper tube from the review withstood 8 Atm. I sealed the end and the sawed gap on the side. If desired, you can use it to reliably solder thick copper or aluminum conductors. But large parts can be a problem. During the heating of the soldering area, the heat will be transferred to the rest of the body, which noticeably slows down the process and you can overheat components that should not overheat - bushings, seals, gaskets.

It is also worth mentioning that there are lots with a lower price, but on the Internet they write that “this is a hoax and there is no better example of this in the world.” Nevertheless, I ordered another pair from another place for $5, but for some reason they are not tracking, maybe I won’t receive them, but if they arrive, I’ll do a little comparison - maybe it’s not worth overpaying.

I’m not a welder, so I apologize if my terminology offends anyone, I tried to explain it “on the fly” and just wanted to share, in case someone like me didn’t know about the existence of such solder for some time)

As always, constructive criticism is welcome in the comments. All the best =)

Is it possible to twist copper wire with aluminum

Let's start with the fact that is it possible to connect aluminum wires with copper wires, and will such a connection not lead to a fire? The answer is yes, you can. But let's first get acquainted with these materials.

If you ask yourself which wiring is better, copper or aluminum, then the choice is, of course, copper. This comes out of the technical characteristics of copper; the cross-section of aluminum wire under the same conditions has to be taken larger. There are also disadvantages: copper is more expensive. It is easier to distinguish copper wire from aluminum by color; copper has a reddish tint, aluminum is gray and white.

Having looked at the electrical performance of metals, the question of which conducts current better disappears. Here's some information:

Resistivity: copper – 0.017 Ohm mm²/m, aluminum – 0.028 Ohm mm²/m.
Heat capacity: copper - 0.385 J/gK, aluminum - 0.9 J/gK.
Elasticity of the material: copper – 0.8%, aluminum – 0.6%.

So why can’t you twist copper and aluminum wires, because twisting, especially with a small cross-section, is the cheapest option in terms of both money and time? The thing is that these materials, when connected, create a galvanic couple.

Galvanic pair - 2 metals of different kinds, the connection of which will lead to increased corrosion. Copper and aluminum are just such a galvanic pair. The electrochemical potentials of the two metals are too different, so rapid corrosion will increase the resistance at the junction and subsequent heating. More details about the compatibility of metals are indicated in GOST 9.005-72. Below is a table with some data on metals:

Galvanic compatibility of meltals

You can achieve high-quality contact between two conductors in different ways (soldering, using a simple terminal block, more expensive WAGO terminals, or an ordinary bolt and nut).

What are the advantages of soldering metals over welding?

Let's look at exactly what advantages soldering of metals gives us, as opposed to welding:

The first and most important advantage is that the metals being soldered are not heated to the melting point. Only the solder melts. As a result of this, the chemical properties of metals are not violated, they do not lose their characteristics;
Before soldering metals, there is no need to more carefully prepare the workpieces, as is done in the case of welding;
You can use simple and unpretentious soldering equipment, which is not so demanding on the power supply of the home electrical network.

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Well, as for the strength of soldering, it is practically in no way inferior to welding. Thus, metal soldering is an excellent option for performing repair work or manufacturing complex structures.

Wire soldering technique

Soldering iron. Since aluminum has high thermal conductivity, you need to use a powerful soldering iron to solder it. In the case of two wires, this can be a device with a power of 60 to 100 W, and for large elements from 100 to 200 W;
Solder. High temperature, if it is possible to heat the part material to 600 °C, or normal, if this is not possible;
Flux. It is used only if it is not included in the solder;
Scraper for cleaning aluminum from protective film. A steel bristle brush, sandpaper or abrasive wheel also work well for cleaning. It is impossible to completely get rid of the oxide film, so the above tools are designed to reduce its thickness, which will simplify the operation of the flux.

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Which is better: welding or soldering aluminum

It’s impossible to say unequivocally that welding or soldering aluminum is better. It depends on the purpose of the parts and the professionalism of the person. For an experienced welder, welding is naturally a more acceptable option, while soldering is more suitable for a craftsman with a soldering iron.

If it is necessary to repair the radiator, it is better to use soldering, since it is much cheaper, and welding is more suitable for carrying out more critical work.

Soldering aluminum is a complicated process, but you can do it yourself at home. However, carrying out work without the use of special materials does not guarantee high-quality adhesion of parts. This will only lead to wasted time and effort. Therefore, you need to immediately prepare for the procedure in order to carry it out efficiently and quickly.

Korovin Sergey Dmitrievich

Master of Architecture, graduated from Samara State University of Architecture and Civil Engineering. 11 years of experience in design and construction.

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There are the following soldering methods:

with rosin;
with solder;
electrochemical.

With rosin

Step-by-step implementation of the method:

The soldering iron is warming up.
The tip is tinned to remove dirt or carbon deposits.
Rosin is applied to the joint seam and melted with a soldering iron.
After melting, use a sting to rub the surface until the oxide film is removed. At the same time, tinning occurs.
After the process is completed, the elements are joined, heated to the melting point, and then left to cool.

Using solders

The method using solder for soldering aluminum is implemented as follows:

The joining surfaces are cleaned mechanically.
The parts are securely fixed.
Local heating of the structure is performed.
The rod with solder is guided along the joint seam, simultaneously heating it with a burner until it melts.

If solder without flux is used, it will need to be used separately. It is pre-applied in an even layer on aluminum.

Electrochemical method

Step-by-step electrochemical soldering of aluminum:

The surface is cleaned of dirt, partly of the oxide film, mechanically.
Apply a thin layer of copper sulfate.
The negative electrode of the current source is connected to the part.
The positive electrode is connected to a high purity copper wire (diameter greater than 1 mm). It is located above the structure on a special stand, ensuring contact only with the treated area.
The power source turns on. The electrolysis process begins to take place.
After removing the oxide film, the wire is removed, and the parts are heated with a soldering iron to the melting temperature or solder is used.

To ensure high quality soldering, it is necessary to apply galvanic coatings with special tools. They will allow for uniform copper plating.

Soldering steel, copper, aluminum, stainless steel, galvanized

Greetings! In this material I will talk about the differences between soldering and welding, how to solder non-ferrous and ferrous metals, and also give some tips on strong soldering and safety precautions. Go.

Soldering galvanized iron

Unlike ordinary tin, galvanized iron has a number of specific characteristics. Firstly, zinc on the surface of the sheet evaporates at a temperature of 960˚C. Therefore, it is not recommended to use powerful burners when working with galvanized sheets.

Secondly, not all solders are suitable for working with galvanized iron. For example, it is highly not recommended to use POS-90 solder, as it destroys the structure of the sheet.

Soldering components:

Solder. It is best to choose POS-30.
Flux - boric acid or zinc chloride.
Soldering iron with a power of at least 40 W.

The technology for soldering two galvanized elements is similar to working with ordinary sheet metal. The main thing is to heat the joint evenly, avoiding overheating of individual areas.

Soldering stainless steel

Stainless steel is an alloy containing nickel and chromium, as well as titanium. Soldering stainless steel is slightly different from similar work with regular or galvanized iron. Depending on the quantitative content of a particular metal in the composition of stainless steel, it will have different physical characteristics.

Thus, a sheet with a high nickel content at a temperature of 500 - 700 ˚C can release carbide compounds. Such sheets are subjected to uniform and rapid heating to avoid destruction of the material structure.

Let's look at the necessary components :

Solder. It is selected depending on the soldering conditions. In open areas or high humidity, preference is given to solders based on silver alloys with a low nickel content. In dry rooms or blast furnaces, chromium-nickel or silver-manganese solders are used. For the initial tinning of two parts, ordinary solder based on tin and lead is used.
Flux is borax in the form of powder or paste.
Powerful gas burner producing temperatures above 800˚C. A soldering iron with a power above 100 W is useful for primary tinning.

Step-by-step soldering technology :

Thoroughly clean the junction of two stainless steel elements.
Secure both sheets and apply soldering acid flux to the joint.
Tin the joint area with a thin layer of tin-based solder. At this stage, use a regular soldering iron. Be careful not to let the solder roll off the sheet. If this cannot be avoided, preheat the sheets and repeat tinning.
Repeat tinning with flux.
Solder both sheets using solder depending on the soldering conditions. Use a gas torch for this step.

If the solder rolls off the sheet even after preheating, use a wire brush. It helps remove the oxide film that may remain on the tinned surface after applying flux.

Soldering of ferrous metals

The quality of fastening of steel products depends on several factors:

steel grades;
porosity of workpieces;
level of cleanliness of the joining seam.

Tin or brass alloys are chosen as solder. They are used depending on the task at hand. An easier way is to use tin. It is easier to work with, however, the final seam will not have a high level of strength.

Brass-based solders are much stronger, but you will need special equipment to work with them.

The work process at the preparatory stage is practically the same. In both cases, the parts are cleaned of dirt and rust. Fix with clamps or a vice. Orthophosphoric acid is used as a flux. After this comes the soldering stage.

Soldering steel with tin

When soldering with tin, select a soldering iron with a power of 100 W or more. To obtain a high-quality seam, both parts are pre-tinned, after which tin solder is fed into the finished seam and soldering is completed.

Soldering steel with brass

Brass melts at temperatures above 900 °C, so to work with such solder you will need a gas torch. It is important to heat both elements evenly. Otherwise, the brass will quickly melt. It will only adhere well to the edges of steel workpieces (which can cause brittleness and stress failure), which will contribute to the formation of cracks in the final product.

Tips for proper and strong soldering of metals

When working with steel or other metals, you must adhere to basic safety rules and also know some of the nuances of soldering.

How to heat and cool metal

An important step before starting work is preparing the workpieces. And here you need to know for sure which alloy you will solder or check it yourself:

See how a metal workpiece reacts to heating with a soldering iron or torch. How quickly an oxide film forms on the surface. It’s better to know this in advance and for sure, otherwise subsequent work will be done in a hurry.
It is best to warm up the prepared and secured parts gradually. Make sure that no overheated spots appear on the metal. The soldering area must be heated evenly over the entire area.
Do not heat only the butt seam; also work on the area near the joint. Most often, you need to warm up 0.5 - 2 cm, depending on the purpose of soldering and the dimensions of the elements being connected.
Use only soldering irons or torches that produce solder at operating melting temperature.
Do not cool the finished seam with cold water or other liquids. Let the metal “rest” and cool evenly for several minutes in the open air.
Remove soldered workpieces from a vice or clamps only after the solder has completely cooled.

Which metals are most strongly soldered to each other?

Unlike welding, in soldering the main indicator of the quality of the finished product is not the grade of steel or metal, but the choice of solder, as well as the technology for forming the solder seam itself.

So the question here is rather about which metal, which solder sticks best to which metal. Of course, the closer in composition and density the solder and metal are, the better the adhesion will be.

In the end, it all comes down to choosing the right solder for each individual case.

You also need to ensure that when connecting two metals, no electric couples are formed. Otherwise, the connection will rust and collapse from the slightest moisture. So a compatibility table for connecting non-ferrous metals with each other would be appropriate here.

The letter “A” in the compatibility table means “limitedly permissible in atmospheric conditions.”

Here are some more simple tips :

Choose solders that are more refractory.
Carefully clean the joints of fastened parts. Apply sandpaper not only to the seam itself, but also 0.5 - 2 cm near the joint on the metal surface.
Tin and overlap seal. Thus, you increase the total area of fastening two or more parts.

Safety precautions when soldering steel at home

Often, neglect of basic rules for working with electrical or flammable appliances leads to loss of health or damage to property.

I strongly recommend following safety precautions when soldering:

Keep the soldering iron on a metal pad or a special holder that takes the heated tip of the tool away from the plane of the table.
Turn off the soldering iron from the mains immediately after finishing work.
Check the quality of the connection of the gas cylinder to the burner itself. Avoid gas leaks.
Work in a well-ventilated area.
Do not leave the burner on if you have already finished working.
Remove any flammable substances from the work area.
Do not touch the heated seam with your bare hands. You may get burned.
Do not touch the solder with your fingers to check the strength of the seam.

By following these measures, you can avoid injuries and also keep your property intact. Solder with pleasure and knowledge!

How to solder aluminum correctly

Sometimes a situation arises when it is not possible to replace old aluminum wiring and you simply need to make a high-quality connection between aluminum and copper. For this, of course, you can use specialized connectors, crimps or terminal blocks, but I want to tell you how you can reliably and efficiently solder copper and aluminum.

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What is the difficulty of soldering?

As you know, aluminum is a very active metal and when interacting with atmospheric air, it is almost instantly covered with an oxide film, which rejects the solder and does not allow aluminum to be simply tinned.

In order for the solder to “stick” well to the metal, you need to remove the existing film and prevent it from forming again until you apply the solder.

Special fluxes were invented specifically for these purposes: they actively use soldering acid, and use a mixture of rosin and acetone.

Preparing inventory

In order to successfully complete this work you will need: a soldering iron with a power of at least 60 W, a knife, pliers, sandpaper or a file, POS 61 or POS 50 solder, F-64 flux or its equivalent, a brush, a sponge and rags.

We solder aluminum with tin and F-64 flux

Important. Soldering of conductive elements using F-64 and any of its analogues is prohibited according to the rules of the PUE. Since the use of acid causes not only the destruction of the oxide film, but also actively destroys the metal itself, and after tinning, this acid cannot be removed and it continues destructive processes under the solder.

In this way you can, for example, solder an aluminum decorative part.

The algorithm for working with F-64 flux itself is very simple. First, we strip the insulation on the aluminum core, then use sandpaper or a knife to process the core itself in order to remove a thick layer of film.

Then we apply flux to the stripped core with a brush and clean it again under flux. Thus, the flux prevents the formation of a new film.

Then, using a well-heated soldering iron, we begin to apply tin to the prepared core. At the same time, you use a soldering iron to rub in solder.

Once you have tinned one track, apply flux again and repeat the procedure. This way you can completely cover the core with solder and then solder it to the place or part you need.

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After you have completely processed the veins, you must rinse it in a soda solution (five tablespoons of soda per 200 grams of water). This is necessary to wash away the remaining active substances, which are part of F-64.

Soldering aluminum to copper using tin and rosin

In order to solder the conductive cores of copper and aluminum wires, you cannot use acid fluxes, but you need to use liquid rosin, which will also ensure a reliable connection.

This rosin can be purchased ready-made, or you can prepare it yourself; for this you will need lump rosin (it is crushed into powder) and pure alcohol. Then we mix these two components in the following proportion: 60% rosin and 40% alcohol. Then put the bottle in warm water, wait until it warms up and mix thoroughly until the rosin is completely dissolved. That's it, the solution is ready and you can use it.

Also, in addition to all the above equipment, we still need to prepare a small container into which we will immerse the stripped end of the wire.

We also remove the insulation and clean the core from a thick layer of foam, then immerse our bare end of the wire so that it is completely in liquid rosin and use a knife to process the core again.

Next, we take a preheated soldering iron and begin to process the core at the very surface of the rosin, rotating it and removing it as the wire is tinned.

The main trick is to tin the aluminum right at the border between the rosin and the air so that the air does not oxidize it.

Make sure that the soldering iron does not lose temperature and, if necessary, remove it from the bath so that it warms up well.

Important. This work produces a lot of smoke, so it is better to do it outdoors or in a room with excellent forced ventilation.

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After you have tinned the aluminum, the residual trace of rosin can be easily removed with a rag soaked in alcohol. You can then twist the tinned aluminum and copper wires into a classic twist and immediately solder it.

Tin will serve as an excellent neutralizer of the galvanic interaction of copper and tin and guarantees that such a connection will last a very long time and trouble-free.

Perhaps the only and significant drawback of such a connection of copper and aluminum is the fact that soldering in a distribution box located under the ceiling and in the absence of the proper supply is almost impossible.

In this case, it is better to use other methods of connecting the wires in the junction box.

That's all I wanted to tell you about soldering aluminum using special solders and regular tin with rosin. I hope you find this article useful and interesting. Thank you for your attention.

How to solder copper to aluminum - Metals, equipment, instructions

Soldering aluminum, as many experts rightly believe, is a rather difficult technological process to perform.

Meanwhile, this opinion can be considered correct only in relation to those situations when they try to solder aluminum products using solders and fluxes that are used to join parts made of other metals: copper, steel, etc.

If you use a special flux for soldering aluminum, as well as the appropriate solder, then this technological process does not present any particular difficulties.

Soldering aluminum using a propane torch

Process Features

The difficulties encountered in soldering aluminum using traditional solders and fluxes are explained by a number of factors, mainly related to the characteristics of the metal.

The main one of these factors is the presence of an oxide film on the surface of aluminum parts, which is characterized by a high melting point and exceptional chemical resistance.

When soldering, such a film prevents the connection of the base metal and the solder material.

Before soldering aluminum products, their surfaces must be thoroughly cleaned of the oxide film, for which you can use mechanical processing or use fluxes that contain potent components.

Duralumin parts prepared for soldering

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 made from it quickly lose strength, and at a certain temperature, in the range of 250–300 degrees, structures made from 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 themselves.

The basis of most low-melting solders used for soldering is tin, cadmium, bismuth and indium.

Aluminum does not bond well with these elements, which makes solder joints made using them very weak and unreliable.

Aluminum and zinc have good mutual solubility, so this element, when used in solders, provides the resulting joint with high strength.

Characteristics of fluxes for soft soldering

Composition of fluxes used for soldering aluminum

Materials used

When soldering aluminum products, you can use solders of the tin-lead group if you thoroughly clean the surface of the parts and use highly active fluxes.

The compounds obtained with their help, due to the poor mutual solubility of aluminum, tin and lead, are characterized by low reliability, and they are also prone to the development of corrosion processes.

To make such compounds more resistant to corrosion, they must be coated with special compounds.

The highest quality, reliable and corrosion-resistant solder joint allows us to obtain solders containing zinc, copper, silicon and aluminum.

Solders containing 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%).

Tin-lead solders have the lowest melting point of all of the above. The highest temperatures are those that contain aluminum and silicon, as well as materials containing aluminum along with copper and silicon. The latter, in particular, includes the popular brand 34A solder, 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.

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

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

Solder HTS-200 for soldering parts made of aluminum and non-ferrous metals

The technology for soldering aluminum necessarily involves the use of a special flux, which is necessary in order to improve the adhesion of the base metal to 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 need to be soldered using tin-lead solder. The composition of fluxes contains elements that form its activity towards aluminum.

These elements include: triethanolamine, zinc fluoroborate, ammonium fluoroborate, etc.

Flux F-64 for soldering light alloys without preliminary mechanical surface treatment

One of the most popular domestic materials is flux brand F64. 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 the refractory oxide film.

Among the popular high-temperature fluxes, we should highlight the 34A material, which contains 50% potassium chloride, 32% lithium chloride, 10% sodium fluoride and 8% zinc chloride.

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, and tin come into difficult contact with aluminum and do not provide sufficient strength. Excellent solubility is observed in the metal in combination with zinc, which makes the soldered areas highly reliable.

Before soldering begins, aluminum elements are well cleaned of oxides and dirt. To do this, you can use mechanical force with brushes or use special fluxes made from a potent composition. Before the procedure itself, be sure to tin the areas to be treated.

The tin coating will protect the part from the formation of oxides. In order to reliably solder aluminum products, it is necessary to choose the right heating tool, taking into account the volume of metal being processed.

In addition, the reliability of the connection depends on the alloy chosen, as well as the flux for soldering aluminum.

Soldering methods

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

with rosin;
using solders;
electrochemical method.

With rosin

This option for soldering aluminum objects, wires, cables is used for small parts.

To do this, the cleaned section of the electrical wire is covered with rosin and placed on a piece of sandpaper with a medium grain size. The wire is pressed from above with the tinned tip of a heated soldering iron.

This action is carried out several times, after which the procedure of soldering the electrical wires itself is performed. You can use a rosin solution in diethyl ether.

In this case, the end of the soldering iron is not removed from the end being tinned, but rosin is added on top. 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 larger than 2 mm require preheating of the joint.

Using solders

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

Soldering of elements can be carried out using light alloy solders containing tin, zinc, and cadmium. In addition, refractory materials based on aluminum are actively used.

Why are light alloy compounds used? Because they allow you to solder an aluminum product at temperatures up to 400 degrees. This does not produce qualitative changes in the properties of the metal and maintains its strength.

Compositions with cadmium and tin do not create sufficient contact reliability and are susceptible to corrosive effects. Refractory materials containing zinc, copper, and aluminum-based silicon do not have these disadvantages.

Electrochemical method

This procedure requires a plating facility. With its help, copper plating is carried out on the surface of a product or wire. In its absence, independent processing of the part is used.

To do this, apply a few drops of a saturated solution of copper sulfate to the area cleaned with sandpaper.

After this, the negative pole of an independent power supply is connected to the workpiece.

They can be a battery, an accumulator, or any electrical rectifier.

A cleaned copper wire with a diameter of about 1 mm, located in an insulated stand, is connected to the positive terminal.

During the electrolysis process, copper will gradually deposit on the part, after which the area is tinning and dried using an electric soldering iron. After this, you can easily solder the tinned area.

Solders, materials, fluxes

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

How to solder aluminum elements? High-quality solder joints are obtained by using solders with silicon, aluminum, zinc, and copper. These materials are produced by both domestic and many foreign manufacturers.

Domestic brands of rods are represented by the most used solders TsOP40, which according to GOST contain 60% tin and 40% zinc, as well as 34A (aluminum - 66%, silicon - 6%, copper - 28%). The zinc used gives high strength to the contact area and provides good corrosion resistance.

In addition to solders, aluminum soldering requires the use of special fluxes containing ammonium fluoroborate, zinc fluoroborate, as well as triethanolamine and other elements.

The most popular is the domestic F64, which has increased chemical activity. It can be used even without first removing the oxide film from products.

In addition to it, 34A is used, containing lithium, potassium and zinc chlorides, as well as sodium fluoride.

Preparation of products

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

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

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

Heating tools

How to solder aluminum at home? Electric soldering irons are used to solder small-sized aluminum products at home. They are a universal tool, quite convenient for soldering wires, repairing small tubes and other elements.

They require a minimum of working space, as well as the presence of an electrical network. Repair of large-sized products and welding are performed with a gas torch that uses argon, butane, and propane.

To solder aluminum objects at home, you can use a standard blowtorch.

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 fiery tongue has a bright blue color. A dim hue, as well as a small flame, indicate an excess of oxygen.

Technological process

The technology for soldering aluminum objects is similar to the process of joining parts of other metal materials. The first step is to clean and degrease the areas of future adhesion. Then the connected elements are installed in working position for ease of processing.

Flux is applied to the prepared area, and the initially cold product begins to heat up using an electric soldering iron or a torch. As the temperature rises, the solder bar begins to melt, which must constantly touch the surface of the elements, controlling the heating process.

Soldering aluminum elements at home with an electric soldering iron is done in a well-ventilated room, as hazardous compounds are released during operation.

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

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

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

Rod for soldering aluminum at home

Hi all! Many people know that aluminum is soldered mainly in an argon atmosphere with a special welding machine, but there is also an option for working with a gas torch, 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 trusted places to buy so as not to get sample No. 2 , but let’s start in order.

Content

Characteristics
Unboxing and appearance
Testing
Results

Characteristics

B-Zn98Al 381-400 Approximate composition (weight%): 2.4 Al – rest Zn Melting point ºС: 360 Tensile strength (MPa): Up to 100 (Al) Density (g/cm3): 7.0

Unboxing and appearance

The last and most profitable purchase was sample No. 3 from banggood.

Came in a small gray package

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The rod is additionally packaged in a transparent zip bag.

5 meters cost me $8 with points, that is $1.6 per meter - go to the store

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

Comparison

The first one I bought was the leftmost sample No. 1 from Ali. Its properties are absolutely identical to sample No. 3 , but 3 meters cost me $12 , that is, $4 per meter , which is almost three times more expensive. check current price

In the center is sample No. 2 . It costs $5 for 3 meters or $1.7 per meter , like sample No. 3

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

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

Testing

Over time, aluminum becomes covered with an oxide film, due to which the surface becomes dull, so, before soldering, the surfaces must be cleaned to a shine, otherwise the solder will simply roll off in balls on the surface, regardless of the degree of its heating. Sample No. 1

In general, it is correct to heat the part to a temperature of about 400 degrees, and then simply move the rod, which will melt and fill the cracks, 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 down the surface like a ball; if it is sufficiently high, it will tin it.

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

Sample No. 2 . It melts very well, emits a lot of smoke, and smells like burnt “aspirin.” It sticks to aluminum, but if you overheat it, it burns out pretty quickly.

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

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Sample No. 3 . I decided to solder the tubes with the outer walls

We try to break the seam. After the tube came out of the vice, I clamped it higher, bringing it out of focus and only noticed this 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 the aluminum tube with a piece of duralumin.

The tear test was also successful.

Results

An interesting wire - aluminum solders perfectly, filling even small gaps, 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 rod is quite suitable for emergency field repairs.

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

Sample No. 3 seemed to me the most optimal . It corresponds to the declared characteristics and costs at least half as much as the others. 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

Bolted connection

Bolted connection of aluminum wires to copper is considered the most affordable, simple, fast and reliable. To get started you will need a bolt, a nut, some steel washers and a wrench.

Of course, it is unlikely that you will be able to use this method to connect wires in an apartment junction box, because now they are produced in miniature sizes, and the resulting electrical unit will be very bulky. But if there are still Soviet-era boxes in your house or when you need to make a connection in a distribution panel, then this bolted method is best suited. In general, it is considered an ideal option when it is necessary to connect completely incompatible conductors - with different cross-sections, made of different materials, multi-core with single-core.

It is important to know that using the bolt method you can connect more than two conductors (their number depends on how long the bolt is long enough).

You will need to do the following:

Strip each connected wire or cable from the insulating layer by 2-2.5 cm.
From the stripped ends, form rings according to the diameter of the bolt so that they can easily be put on it.
Now take the bolt, put a washer on it, then a ring of copper conductor, again a washer, a ring of aluminum conductor, a washer and tighten everything securely with a nut.
Insulate the connection using insulating tape.

The most important thing is not to forget to place an intermediate washer between the aluminum and copper wires. If you will connect several different conductors, then you do not need to place an intermediate washer between the cores of the same metal.

Another advantage of this connection is that it is detachable. At any time you can unwind it and, if necessary, connect additional wires.

How to properly bolt a wire connection is shown in detail in this video:

Stranded wires

As mentioned earlier, conductors with many cores should not be overly pinched. To connect stranded wires, sleeves or ordinary twists are most often used. We'll talk about these methods in a little more detail below.

Sleeves

The sleeve is a protective cap made of plastic, under which there is a hollow metal tip. First of all, it is necessary to remove the insulating layer from the conductor. Next, the strands are twisted into one whole, and the resulting “pigtail” is directed into the sleeve. Next, the sleeve is crimped (pliers are suitable for this operation). The tip of the sleeve is inserted into the terminal. To increase the reliability of the connection, the sleeve can be treated with solder.

Twist

Among professional electricians, twisting is not respected. However, there are situations when twisting is the most convenient way out of the situation (for example, to create a temporary connection or in the absence of the necessary materials).

So, twisting of copper and aluminum is permitted only after thorough cleaning of the aluminum surface. If the copper conductor has many cores, all existing wires must be collected into one “pigtail”. The copper also needs to be coated with solder - this will improve contact.

When twisting, it is important to prevent the wires from breaking. It is best to cover the ends with insulating protective caps, which can be purchased at any hardware store.

Note! Twisting is not allowed in rooms with humid air.

So, there is nothing complicated in connecting copper and aluminum conductors. You just need to remember the cost of a mistake: incorrectly connected wires can cause not only the failure of electrical appliances, but also a fire.