Soldering operations are quite common not only in professional areas in production and construction, but also in everyday life. They are used to produce interatomic inseparable compounds between small parts and elements. There are different types of soldering, differing in technological nuances, used consumables, blanks, etc.
Technology Overview
This is a bonding method in which a bonding melt (solder) is used with characteristics suitable for specific conditions. Both the soldering active element and the workpieces are pre-heated, due to which a material structure that is malleable for connection is formed. The temperature regime should be higher than the peak heating point, bypassing which the metal parts soften and begin to transition to a liquid state. An important characteristic of any type of soldering is the time of thermal exposure under the melt. This is the period from the start of heating to the hardening of the solder after the connection is completed. On average, the operation takes 5-7 minutes, but there may be deviations from this range - this depends on the characteristics of the workpiece and the area of the processed unit.
Soldering lamps
The most common tool for brazing various workpieces, which allows to obtain high-temperature heating by burning alcohol, kerosene and other types of liquid fuel. In the process, a flare fuse is pulled out from the nozzle of the apparatus, which is then sent to the target melt section. Such devices can be used not only to connect parts, but also in heating operations of structures and mechanisms. Soldering apparatuses are also used before removing paint coatings. The average heating temperature of a lamp soldering iron is 1000 - 1100 ° C, so it can also be used in welding. The most productive models include gasoline lamps. They quickly gain optimum operating temperature and can handle most standard soldering operations. The design of the devices provides for a can for fuel, as well as a flame regulator, which allows you to vary the power of thermal exposure.
Soldering torches
A wide group of gas soldering irons that can be connected to a can of fuel or to a central source of fuel. The first supply option has the advantage of autonomy. A spray can, like a gas lamp, can be used independently of external communications. In choosing such an apparatus, one should take into account power, operating temperature, type of gas used, time to ready for operation, etc. For example, a standard gas soldering torch runs on propane-butane and reaches a heating temperature of up to 1300 ° C. The period of continuous thermal exposure can reach 3 hours, but this time will also depend on the volume of the connected spray can. There are burners and the type of ignition system. The simplest models are switched on mechanically, and in more modern versions piezo-ignition is used.
Electric soldering iron
Also a common type of soldering equipment in the domestic environment, which is safe (compared to gas appliances) and compact in size. But immediately it is worth emphasizing the disadvantages. Firstly, such devices are dependent on the mains, which limits their scope. Secondly, electric soldering equipment maintains a low heating temperature in the range of 400 - 450 ° C. This is due to the fact that part of the energy is lost in the process of converting electricity to heat.
In choosing a device, the maximum voltage must be taken into account. So, in workshops and in factories, standard models of 220 V are used. In everyday conditions, devices that operate on transformers of 12 and 24 V are often used. Tasks that can be solved by electric soldering irons are mainly limited to fixing small equipment, restoring contacts of microcircuits, connecting plastic parts, etc.
Soldering stations
To perform group or continuous soldering operations, multifunctional equipment is used. The soldering station is characterized by wide possibilities for adjusting the operating parameters, as well as higher temperature indicators of heating. Suffice it to say that devices of this type operate at a power of 750 - 1000 W, connecting to networks with a voltage of 220 V. As a rule, this is professional soldering equipment, but there are also analogues for domestic use. For example, apparatus for group operations at home may include several interchangeable tips of various formats, coasters, solder removers, wire cutters and other auxiliary accessories. Now it is worth familiarizing yourself with different technological approaches to soldering processes.
The main types of soldering
Distinguish techniques for performing operations on the joint and the gap. So, if the gap between the connected elements is less than 0.5 mm, then the soldering will be with a gap. Exceeding this interval means that the connection is butt. Moreover, the joints can have different configurations - for example, X- and V-shaped. Soldering with a gap is carried out only with liquid solder, which during operation is sent to the intermediate zone. Butt-bonded standard soldering involves filling the free space with solder under the influence of gravity.
Classification of soldering by temperature conditions
Today they use soft, hard and high-temperature soldering, which is used mainly in industries and in construction. The first two techniques are very similar in many ways - for example, in both cases, the operating temperature is 450 ° C and lower. For comparison, high-temperature compounds are made in a mode of at least 600 ° C, and more often above 900 ° C.
At the same time, low-temperature processing can provide a high-quality connection. The most advantageous is the use of solid solder, due to which high strength and refractoriness of the parts are achieved. Adding copper to the gap or joint will also increase the ductility of the workpiece. If you want to get a flexible and elastic structure, then use soft soldering.
Classification of solders
It is conditionally possible to divide modern solders into two groups:
- Melting under low temperatures.
- Melting under high temperatures.
As already noted, low temperature brazing is performed at 450 ° C and below. The solder itself for this kind of operation should soften already at 300 ° C. Such materials include a wide group of tin alloys with the addition of zinc, lead and cadmium.
High-temperature melt media are used for soldering at temperatures of the order of 500 ° C. Mostly these are copper compounds, which also include nickel, phosphorus and zinc. It is important to note that, for example, tin-lead-cadmium solder , in addition to a lower melting temperature, will differ from copper alloys in mechanical strength. The ratio of resistance to physical pressure can be represented as follows: 20 - 100 MPa versus 100 - 500 MPa.
Types of Fluxes
During thermal exposure, an oxide coating forms on the surface of the metal billet, which prevents the formation of high-quality compounds with solder. To eliminate such obstacles, different types of soldering fluxes are used, some of which also eliminate traces of rust and scale.
Fluxes can be classified just by compatibility with solders (hard and soft) or by temperature resistance. For example, for soft soldering of heavy metals use means marked F-SW11 and F-SW32. For the hard connection of heavy alloys, soldering fluxes of the types F-SH1 and F-SH4 are used. It is recommended that light metals such as aluminum be pretreated with compounds of the F-LH1 and F-LH2 groups.
Induction brazing method
This soldering technology has several advantages over the classical method of connection under the melt. Among them, one can distinguish the minimum degree of oxidation of the workpiece, which in some cases eliminates the need for fluxes, as well as a low warping effect. As for the target materials, these include both soft and hard alloys, as well as ceramic with plastic. For example, the optimal solder for copper in this case will be labeled L-SN (modifications SB5 or AG5). As a source of thermal energy during induction exposure, both manual tube devices and machine units of the corresponding power can be used. Generating sets are also involved in production, when it is necessary to obtain a long-term soldering of nodes of a large area. Also, a multi-seat inductor is included in the work, which can alternately receive blanks. According to this technology, in particular, a manual cutting tool is made.
Ultrasonic soldering
Another modern high-tech method of soldering, the development of which was caused by the need to eliminate a number of characteristic disadvantages of electrochemical methods of connection. A key feature of this technique is the ability to replace conventional flux as a means of eliminating oxides. The cleaning function is performed by the energy of ultrasonic waves, which causes the cavitation process in the solder. At the same time, the tasks of thermal binding action from the side of the melt are fully preserved.
The superiority of technology in terms of connection speed is also noted. If we compare the ultrasonic radiation with the effect that the tin-lead solder gives, the intensity of collapse of the cavities of the treated unit will be several times higher. As observations show, ultrasonic waves with a frequency of 22.8 kHz provide a solder closing speed of 0.2 m / s.
There are economic advantages of this method. They are also associated with changing approaches to the use of fluxes and solders. In the production of electrical devices for the assembly of monolithic capacitors, current converters and other devices, metallization with palladium, silver and platinum pastes is widely used. The process of ultrasonic soldering allows you to replace precious metals with cheaper analogues without loss in performance of the future product.
Features of soldering-welding
Soldering as such has many similarities with traditional welding technologies. Also used is the heating of the workpieces and third-party material that affects the formation of the seam. But, in comparison with welding techniques, soldering does not provide for an internal melt of the workpiece structure. The edges of the parts, as a rule, remain solid, although they are exposed to heat. Nevertheless, the complete melt of the workpiece gives a stronger connection. Another thing is that to achieve such a result, more powerful equipment may be required. When using liquid solder for copper, non-capillary soldering with a dense filling of the seam is quite feasible. This connection method partially relates to welding, since it increases the adhesion of the structures of two or more workpieces. Non-capillary soldering is recommended by electric arc devices or an oxygen-acetylene torch.
Conclusion
It is not only the right choice of technology, solder with flux and equipment that affects the quality of the connection during the soldering process. Often crucial are the small organizational procedures associated with the preparation of materials and subsequent processing. In particular, the use of brazing alloy requires a multi-stage cleaning of the target surface using abrasive grinding and chemical exposure to carbon tetrachloride. The part ready for work should be clean, smooth and as even as possible. Directly during soldering, it is also recommended that special attention be paid to the method of fixing the workpieces. It is advisable to fix them in a clamping tool, but so that the latter is protected from chemical and thermal effects.
Do not forget about safety. Particular care requires active supplies - flux and solder. For the most part, these are chemically unsafe elements that can release toxic substances under high temperature exposure. Therefore, at a minimum, skin and respiratory organs should be protected during operation.