Solder for soldering copper, aluminum, brass, steel, stainless steel. Solder composition for soldering. Types of solders for soldering

When it is necessary to securely fasten various solid connections among each other, soldering is usually chosen for this purpose. This process is widespread in many areas of industry. We have to solder and home masters.

This operation helps not only when the TV or computer is out of order, and to restore it is necessary to replace the burnt chip or chip. With the help of this process, refrigeration equipment, industrial systems are restored. Soldering helps if you need to get a sealed connection. In addition, some materials simply can not be combined in another way. Aluminum, copper, brass can not be welded together. In order to get a quality and reliable, as well as a sealed connection, you need not only good equipment and special skills, but also suitable consumables - solders and fluxes for soldering.

Alloys of solders and types of flux are selected depending on the materials with which they will have to work. For example, when dealing with aluminum products, another flux is needed, different from that suitable for copper or silver. Below we consider the main characteristics of each of them and choose the most optimal variant for work.

Solder for soldering: main characteristics

Various metal alloys are used as it . Also there are compositions on the basis of pure metal. In order for high-quality joints to be created with the help of this or that solder, these materials must differ in some qualities.

Wetability

First of all, any kind of solder should have excellent wettability. Without this feature, the soldered parts simply can not reliably contact each other. What is wettability? This is such an interesting phenomenon, when the strength of the bonds between particles of a solid and a liquid is higher than that of liquid molecules. If there is wettability, then the liquid will spread over the surface and fall into all cavities. So, if the brazing solder does not wet, for example, copper, then it can not be used with this metal. For soldering it, lead is not used in its pure form. Its wetting characteristics are very low and one can not expect a high quality connection.

Melting temperature

Whatever the type of solder, the temperature at which it starts to melt must necessarily be below the melting of the soldered materials. Also, it should be higher than the operating temperature of the parts.

Talking about the melting point, there are two points. This is the value at which the low-melting components begin the melting process, and the minimum, where the alloy will turn into a liquid. The difference between these two temperatures is called the crystallization interval. If the place of soldering is within this difference, even small mechanical loads on the part can completely destroy the structure of the solder. In this connection, high brittleness and resistance will be noted. Remember the main thing: do not influence the connection in any way until the solder for the soldering has fully crystallized.

Important properties of solders

Whichever type and type of alloy, with whatever material it is used, it should not contain heavy metals or any other toxic substances above the established rate. The composition of the solder is maximally consistent with the material of the parts. Otherwise, it will not be possible to get a reliable connection. There will be excessive fragility.

Any solder, regardless of the type and purpose, should be thermostable. Also the solder for soldering must have an electrical stability. The coefficients of thermal expansion and thermal conductivity should be taken into account. They should not significantly differ from those that apply to soldered products.

Types of solders for soldering

All existing alloys for this operation are divided into soft, or fusible, where the melting point is up to 450 degrees Celsius, and solid. Here it significantly exceeds the above value.

Soft solders

One of the most popular and common are tin-lead alloys with different components content. In order to give the material the necessary characteristics, various additional ingredients can be added to the brazing solder. For example, bismuth and cadmium are used to reduce the melting point. The addition of antimony makes it possible to increase the strength of the soldered joint.

Alloys of lead and tin have a low melting point and low strength. They should not be used for parts, the operation of which involves a serious load. Also, these solders are not recommended if the working temperatures of the parts are above 100 ° C. If you have to solder the loaded parts with soft solders, you should try to increase the contact area of the two products.

Among the most popular soft materials, there are POС-18, POS-30, POS-40, POS-61, POS-90. The figures are indicated here for a reason. This is the percentage of tin in the alloy. In industry, it is often used in the production of electronics, instrumentation. In everyday life, they can connect a variety of details: the scheme of televisions, microwave ovens, electric kettles and other small appliances.

Purpose of soft solders

PIC-90 is designed to work with parts that will then be processed by galvanic technology. POS-61 can be used to repair high-precision equipment. Also, the alloy is ideal for joining high-responsibility parts from a variety of materials. PIC-61 has proven itself as a solder for brazing copper and brass. The solder is suitable when it is necessary to achieve strong connections with a high degree of electrical conductivity.

POS-40 is widely used for operations with unreliable and inaccurate details. In this case, the working area can be heated to high temperatures. POS-30 is suitable for soldering copper or brass, steel alloys and iron.

Solid

Among the refractory alloys, only two groups are widely used and widely used. Basically it is copper or silver alloys.

The first group includes solders made of copper and zinc. They are well suited for those connections that will only be affected by static loads. The fragility of these alloys does not allow them to be applied in knots that will experience impacts or any vibrations.

Copper solders or zinc-based compounds include PMC-36 and PMC-54. The first is an ideal solder for soldering brass and any other copper connections. The second is suitable for work on copper parts, bronze or steel.

If it is necessary to connect two steel parts, then you can use pure copper, brass of L-62, L-62, L-68 brands. These brass-based solders make it possible to create stronger and more flexible joints. Copper alloys do not have such characteristics.

Alloys of silver are considered to be of the highest quality. The composition may also contain zinc and copper. PSr-70 - solder for brazing copper, for working with brass or silver parts. This element is suitable in case the connection point must conduct electricity. PSr-65 is used in the production of jewelry products, fittings, water pipes. PSr-45 is needed to connect those parts that operate under vibration and shock loads.

Other types

There are also other, less popular solders. Often they are used for rare metals or for work in special conditions. For example, nickel-based compositions are designed for products that function in elevated temperature conditions. They are also soldered with stainless alloys. Solders based on gold are used for working with vacuum tubes. There are corresponding solders for magnesium.

Form of issue

Materials and compositions for soldering are delivered in a variety of forms. So, it can be a wire, a thin foil, a tablet, a powder. In addition, the solder is available as a paste or granules. The shape depends on how the solder will be supplied to the work area.

Features of soldering aluminum

The connection of aluminum parts by soldering is used in industry and at home. For example, the frames of modern bicycles are made of aluminum alloys - in the process of extreme driving they often break down. The question is: which solder to choose?

It is believed that soldering aluminum is a very complex process. But in fact it is so, if in the process of using materials for stainless steel or brass, steel, copper. The reason for this is the oxide film. It does not give the necessary level of wettability, and the base metal does not dissolve.

The soldering of aluminum and alloys based on it

For the work to be carried out to the proper level, the solder for soldering aluminum should contain silicon, aluminum, and also copper, zinc and silver. Today, you can find compounds on the market, where all these components are in different proportions.

When choosing a reliable solder, it is important to consider the following. The maximum resistance to corrosion and high strength will be the connection that was made with the solder, which contains a lot of zinc.

Also for aluminum, compounds based on tin and lead can be used. But it is important to prepare the working surface qualitatively, to brush it with stainless steel and use active fluxes. But experts do not recommend using such an element.

Any solder for soldering aluminum high temperature. The most optimal, which allow to obtain a reliable connection - aluminum-silicon and aluminum-copper-silicon.

How to solder copper?

As already noted above, you can work with it with most of the compounds. You can use both low-temperature low-melting and solid solders. Still apply compositions on the basis of tin with lead, tin, silver, copper with silver and zinc.

If you need to repair the computer motherboard or fix the TV in the country, any fusible elements will do. If it is necessary to weld fittings on pipes or repair a water pipe or a refrigerator, then only a hard solder for brazing copper will do. This is how you can get a qualitative result.

Stainless steel

If you want to connect parts from stainless steel, then professionals recommend using bars of tin and lead. Materials with cadmium are also well suited. It is possible to use low-melting alloys based on zinc. However, do not use them together with carbon or low-alloy steels. The best solder for soldering stainless steel is a composition based on pure tin. In addition, only tin is allowed if the place of soldering is in contact with food.

If the work will be carried out in a dry or inclement atmosphere, then silver with manganese, chromium-nickel solders or pure copper should be used (and even better brass). When soldering occurs in corrosive conditions, use silver tinols with a small portion of nickel.

Soldering of steel

To connect two such details is not difficult. Available and effective solder for soldering steel - PIC-41. There is also POS-60 and others, you can apply even pure tin. But the zinc compounds are bad. Especially when it comes to carbonaceous or low-alloy materials.

Fluxes for soldering

During the operation, the flux plays an equal role than solder. It is a chemical solvent and absorber of oxides. It also protects metals from oxidation and increases wetting.

To work with elements based on lead and tin, hydrochloric acid, zinc chloride can be used as a flux. Also suitable is borax, ammonium chloride. These are active fluxes. To inactive can be attributed rosin, petroleum jelly, olive oil and many other substances.

For example, solutions of hydrochloric acid can be used with soft solders. Zinc chloride is used with brass, copper, and steel. Ammonia sleeps perfectly dilutes and dissolves fatty substances. For aluminum, a composition of tung oil, rosin, calcined zinc chloride is used. Concentrated phosphoric acid can also be used .

So, we found out what kind of solders are, and which one is best used in different cases.