Popular soldering fluxes
A good soldering connection can be achieved by observing certain requirements, among which the correct choice of flux is important. There are many formulations of organic, mineral and mixed origin. They have differences in properties and recommendations for use.
What to use it for
A novice solderer does not always appreciate the importance of the functions performed by fluxes. There are parts, solder, soldering iron or other tools for soldering. I warmed everything up, connected it, cooled it, washed it - and it was done.
In fact, the process is more complicated. Only surfaces free of oxide deposits and other impurities can bond reliably.
The solder should spread evenly in the required place, and not just anywhere. The materials must have a suitable combination that maximizes adhesion.
To do this, you need to reduce the tensile forces on the surfaces. For many types of soldering, environmental influences are not allowed. It is necessary to isolate the work area from the surrounding atmosphere.
Therefore, the main functions of flux are as follows:
- removal of oxide deposits and impurities,
- ensuring good solder distribution,
- improving adhesion of materials,
- protection of the connection point from air and moisture.
A good flux composition can handle all tasks. There are many of them on sale. You can make good compositions at home, but it is better to buy ready-made compositions that have been tested many times in their work.
Choosing a flux for soldering is easy. You need to have information about the available brands and take into account the specifics of the upcoming soldering.
Popular varieties
Compositions of different consistencies are widely used. The most famous fluxes that can be chosen for soldering certain parts include:
- rosin and its alcohol solutions;
- glycerin solutions;
- borax;
- soldering grease;
- phosphoric acid;
- soldering acid (a solution of zinc chloride in hydrochloric acid);
- some brands of gel fluxes (Flux-Plus, RMA-223).
There are compositions in the form of tubes or paste briquettes containing both flux and solder. In many cases, this is a very convenient option that simplifies soldering.
When thinking about which flux can be used for soldering with a hairdryer, do not hesitate to choose paste. It is suitable mainly for surface mounting, working in hard-to-reach places, with SMD parts.
The best soldering flux performs all the necessary functions at once. There are different classifications of soldering aids.
Fluxes can be very active, good at removing oxides and other impurities on the surface. The opposite, unpleasant side of their action is the possibility of oxidation of the metal of the part. Soldering must be carried out carefully, followed by washing the work area.
There are compositions with moderate action that provide sufficient surface cleaning and good solder distribution.
With rosin
When planning the installation of electrical circuits or radio components using easily melting solders as flux, it makes sense to choose pure rosin or mixtures based on it.
The advantage of natural resin lies in its inertness. It perfectly protects the joint from oxidation and does not cause corrosion, reduction, or dissolution of metal parts.
After using regular light rosin, it is enough to clean the work area with a brush or cotton swab slightly moistened with alcohol. You can use acetone as a solvent.
For soldering in hard-to-reach places, it is advisable to choose a solution of rosin in alcohol. If you don’t have rosin, you can take pine resin. The result will not disappoint. Alcohol is sometimes replaced with cologne, gasoline, acetone, and ethyl acetate.
If the soldering area will be subject to high thermal loads in the future, it makes sense to add glycerin to the mixture of rosin and alcohol.
Ethyl alcohol of any degree of purification is suitable for preparing solutions. You need to take regular rosin, and not specially prepared for rubbing bows. “Musical” types may have impurities that interfere with soldering.
Based on hydrochloric acid
A common component with great activity are compounds based on hydrochloric acid. It quickly removes all oxides when soldering steel products with soft solders.
The use of hydrochloric acid is not recommended for radio installation work. Acid activity can have unpleasant consequences. The treated areas are easily subject to subsequent corrosion, so the working area should be thoroughly washed with hot water after soldering.
Work with hydrochloric acid should be carried out carefully, under a fume hood. Vapors can damage the mucous membranes of the eyes and respiratory tract.
To work with brass, copper and steel alloys, it is advisable to choose zinc chloride in a solution of hydrochloric acid. It is easily obtained at home by adding metal to acid.
It is convenient to carry out specific types of soldering with a flux paste consisting of a saturated aqueous solution of zinc chloride and petroleum jelly.
For soldering nickel alloys and platinum, a multicomponent mixture of zinc chloride, ethyl alcohol, glycerin, and water is recommended.
Non-ferrous and precious metals are repaired by soldering with a flux consisting of rosin and zinc chloride in alcohol. After work, the joint is washed with acetone.
If you need to obtain connections with increased strength when soldering the same alloys, you should choose a flux paste made from rosin, zinc chloride and technical petroleum jelly. Washing is carried out with swabs moistened with acetone.
With weak acids and borax
Many craftsmen try to choose time-tested products for soldering. They prefer to work with stainless steel, nichrome, and some other metals and alloys, using concentrated phosphoric acid.
Flux is available and inexpensive. Its main disadvantages include the ability to form products that conduct electric current well. If this circumstance significantly worsens the performance of the soldered part, you should choose a different flux.
For soldering metal parts with soft solders, a group of mixtures with the designation LTI is recommended. There are several varieties of these products containing different ratios of several nitrogen-containing compounds.
For each type of flux of the LTI group, there are strictly defined recommendations that must be taken into account.
High-temperature soldering of cast iron, copper alloys, and steels with a high carbon content is carried out using borax as the flux. Its melt removes oxides and other impurities well. After work, the soldering area can be easily cleaned mechanically.
No cleaning required
In recent years, the popularity of no-clean soldering fluxes has increased. The advantage of such solutions and gels is that they save time.
After work, there is no need to thoroughly rinse the joint because the mixtures do not contain components that cause metal deterioration.
No-clean flux gels are applied with special applicators that are commercially available. You can make such devices yourself from a disposable syringe and a rubber or silicone tube. No-clean flux is chemically inert, but it is still better to wipe off its residues from the joint surface.
In order to choose a successful flux for soldering, you need to think through all the nuances of the upcoming work, study the composition of the metal, and provide acceptable cleaning methods.
An important factor is the requirements for the quality of the future connection and the operating conditions of the part. In many situations, you should inquire about the electrical conductivity of the flux and the residual resistance of the future joint.
Analysis of all the information will allow you to choose the right flux and get a good soldering result.
Source: https://svaring.com/soldering/flus/populyarnye-flusy-dlja-pajki
Solders for soldering. Types and properties. Composition and fluxes. Melting
Soldering is often used to connect various metal parts together. This type of connection is popular in various areas of life and production. It is most often used by radio amateurs and home craftsmen.
Soldering can help out both when repairing computers, TVs, radio equipment, and in industry, repairing refrigerators. Soldering is good at creating a tight connection. And some materials simply cannot be combined in any other way.
Not all metals can be joined by welding. And in order for the soldering to be high-quality and airtight, you need work skills, good tools and appropriate solders and fluxes.
The compositions and types of solders and fluxes are selected in accordance with the materials from which the materials being joined are made. For example, aluminum requires a completely different flux than copper. Let's consider the basic properties of solders, their applicability, and features of use.
Basic properties
Various metal alloys are used as solder. There are alloys based on one pure metal, usually tin. The metals that make up solder differ from each other in different parameters.
Wettability
Any solder for soldering must necessarily have the property of wettability, otherwise the parts to be joined will not be connected by high-quality soldering.
Wettability is a phenomenon in which the reliability of the bond between the molecules of a solid and a liquid is greater than that of the liquid. If there is good wettability, the liquid disperses over the surface and fills all its cavities. When solder does not sufficiently wet the metal, it is not used for that metal. Pure lead is not used for soldering copper; it does not wet the copper.
Melting temperature
Regardless of the type of solder, the melting point of any type should not be higher than the temperature of the parts being soldered. However, it must be higher than the operating temperatures of the materials so that the solder does not melt during operation of the soldered device.
There are two temperature thresholds in this matter. The first is the temperature at which the melting of the most fusible components of the solder just begins, and the second is when all the solder has turned into liquid. The interval between these two values is called the solder solidification interval.
If the place connected by soldering is at a crystallization temperature, then the soldering place can quickly collapse, even from a small load, since the connection will have increased electrical resistance and fragility. When soldering, you need to know that until the solder has completely hardened, you cannot apply any loads to it.
Properties of solders
Any solder composition should not contain substances that have toxic properties to humans beyond the norm. Solders for soldering must have the properties of thermal stability and electrical stability. When choosing a solder, the thermal conductivity of the solder and its thermal expansion are taken into account. They must be level with the soldered parts.
Types of solders
All solders for soldering are divided into hard and soft. The melting point of hard solders is more than 450 degrees, and soft solders - up to this value.
Soft wires for soldering
The most popular of them are alloys of tin and lead with different percentages. To impart special properties to the solder, auxiliary components can be added to it. Cadmium and bismuth are used to reduce the melting point. Antimony increases soldering strength.
Tin and lead solders have a low melting point and low strength. It is better not to use such solder for critical parts. If you have to soft solder parts that are subject to heavy loads, it is recommended to increase the soldering area of the parts.
The most popular soft steel solders are from POS - 18 to POS - 90. The numbers in the marking indicate the percentage of tin in the solder. These brands of solders are used in the production of instruments and electronic devices.
POS-90 is used for soldering parts that are subsequently subjected to galvanization. POS-61 is used for soldering precision devices and critical parts made of various materials.
They are used for soldering brass and copper when connection strength and increased electrical conductivity are needed.
POS-40 is used for non-critical parts that do not require special precision. The soldering area can be heated to a high temperature. POS-30 goes well with brass and copper, as well as steel alloys.
Brazing alloys for soldering
Among hard solders with a high melting point there are two groups: alloys of copper and silver. Copper types of solders include solders based on zinc and copper, which are well combined for connections intended for static loads. These alloys are brittle, so they should not be used for soldering materials subject to shock or vibration.
Other types of solder
There are other types of solder that are rarely used. They are necessary for soldering rare metals, or for special special conditions. There are nickel-based solders used for parts operating at high temperatures or made of stainless steel. Gold solders are used for vacuum tubes. Magnesium solders are also available.
Release form
Solders are produced in various forms and packaging. Most often, solders are made in the form of wire, foil, or powder or tablets. There are also granular solders and solder pastes. The shape of the solder is selected depending on the type of soldering zone.
Soldering aluminum
Aluminum parts are connected by soldering, using special solders. Aluminum soldering is used in industry and domestic conditions.
In general, soldering aluminum is considered a difficult job. This happens when the type of solder is chosen incorrectly. They take the wrong kind of solder, which is intended for other metals. The reason for difficult soldering is the formation of an oxide film, which does not allow good wettability of aluminum.
To solder an aluminum part, a solder containing zinc, silver, copper, aluminum and silicon is used. There are many solders with such components in different proportions in the trading network. When choosing, it should be taken into account that the greatest corrosion resistance and joint strength is achieved by solder with a significant zinc content.
Aluminum can also be soldered with ordinary lead and tin solder, but this requires high-quality surface preparation, which includes cleaning with a stainless steel wire brush. When soldering, you need to use active flux. But this method is rarely used.
Aluminum soldering is carried out at high temperatures. The most commonly used solders for soldering aluminum are aluminum-copper-silicon compounds.
Soldering copper
Copper is the easiest to solder. Almost all types of solders are combined with it. Both soft low-melting solders and hard types are used, as well as alloys of tin, lead, silver, zinc, etc.
Any soft solder is suitable for repairing a computer or TV. Hard solders are used for soldering pipes, plumbing, and refrigerators. By following these simple rules you can get a good result.
Soldering stainless steel
To connect parts made of stainless steel by soldering, experts recommend using solder consisting of lead and tin. A good result is obtained with solder containing cadmium. Zinc-based soft solders can be used.
They cannot be used in conjunction with low-alloy steels, as well as carbon alloys. The best solder option for stainless steel is pure tin solder, especially if the soldering will come into contact with food products.
When soldering is carried out in a dry place or in an oven, use manganese with silver, pure copper or nickel and chromium solders. During soldering under corrosive conditions, silver-based tinols with a portion of nickel are used.
Soldering steel
An effective solder for joining steel parts is POS-41. Other soldering alloys can also be used, but they are not entirely suitable for this purpose. Zinc-based solder does not combine well with steel, especially low-alloy and carbon alloys.
How to make your own solder
To prepare your own solder, the component parts (usually lead and tin) are weighed on a scale. This mixture is melted in a crucible on a gas burner. The molten composition is stirred with a metal rod.
Next, using a small steel plate, remove the slag from the surface of the molten solder, then carefully pour it into molds made of tin or plaster.
Melting is carried out in a ventilated area, in compliance with safety measures, that is, wear glasses, an apron, and gloves.
Types of fluxes
No soldering can be done without flux, just as without solder. It is a chemical that dissolves and absorbs oxides. Flux protects the metal from oxidation and promotes wetting of the parts to be joined.
For the soldering process with solder based on tin and lead, a flux based on hydrochloric acid or zinc chloride is used. Ammonium chloride or borax can also serve as a flux. These fluxes are active. Passive fluxes consist of rosin, oil, petroleum jelly and other similar substances.
For example, with soft types of solders, you can use a solution of hydrochloric acid. Zinc chloride is used with steel, copper and brass. Ammonia can dissolve fatty substances. For soldering aluminum alloys, a mixture of tung oil, zinc chloride, and rosin is used as a flux. Phosphoric acid also has its uses.
Related topics:
Source: https://electrosam.ru/glavnaja/slabotochnye-seti/pripoi-dlia-paiki/
What kind of solder should I choose for soldering wires?
One of the most reliable methods of connecting wires is soldering. This is a process in which the space between two conductors is filled with molten solder. In this case, the melting temperature of the solder must be lower than the melting temperature of the metals being joined. At home, soldering is most often used with a soldering iron - a small device powered by electricity. For normal operation, the power of the soldering iron must be at least 80-100 W.
What you need for soldering with a soldering iron
In addition to the soldering iron itself, you will need solders, rosin or fluxes; it is advisable to have a stand. While working, you may need a small file and small pliers.
Most often you have to solder copper wires, for example, on headphones, when repairing household appliances, etc.
Rosin and fluxes
To get a good connection between the wires, it is necessary to clean them of contaminants, including oxide film. While mono-cores can still be cleaned manually, multi-core conductors cannot be cleaned properly. They are usually treated with rosin or flux - active substances that dissolve contaminants, including oxide film.
Both rosin and fluxes work well, but fluxes are easier to use - you can dip a brush into the solution and quickly process the wires. You need to put a conductor in rosin, then heat it with a soldering iron so that the molten substance envelops the entire surface of the metal. The disadvantage of using fluxes is that if they remain on the wires (and they do), they gradually corrode the adjacent sheath. To prevent this from happening, all soldering areas must be treated - the remaining flux must be washed off with alcohol.
Solders and fluxes for soldering copper wires with a soldering iron
Rosin is considered a universal remedy, and fluxes can be selected depending on the metal you are going to solder. In the case of wires, this is copper or aluminum. For copper and aluminum wires, use LTI-120 flux or borax.
A homemade flux made from rosin and denatured alcohol (1 to 5) works very well, and it’s also easy to make with your own hands. Add rosin to the alcohol (preferably dust or very small pieces of it) and shake until dissolved.
Then this composition can be used to treat conductors and strands before soldering.
Solders for soldering copper wires with a soldering iron use POS 60, POS 50 or POS 40 - tin-lead. For aluminum, zinc-based compounds are more suitable. The most common are TsO-12 and P250A (made of tin and zinc), grade A (zinc and tin with the addition of copper), TsA-15 (zinc with aluminum).
Convenient to use solder with rosin
It is very convenient to use solders that contain rosin (POS 61). In this case, there is no need to pre-treat each conductor in rosin separately. But for high-quality soldering, you must have a powerful soldering iron - 80-100 W, which can quickly heat the soldering area to the required temperatures.
Auxiliary materials
In order to properly solder wires with a soldering iron, you also need:
- Stand. It may be completely made of metal or have metal holders for a soldering iron attached to a wooden/plastic stand. It is also convenient if you have a small metal box for rosin. Soldering with a soldering iron is more convenient with a homemade or factory-made stand - not very important
- File. Before work, sharpen the tip of the soldering iron. It should be smooth and clean without traces of soot. Then it is easy to solder. This is how you need to sharpen the soldering iron tip
- Pliers. It is difficult to hold the wires with your fingers while soldering - copper and aluminum have high thermal conductivity, which leads to rapid heating of nearby areas. Therefore, it is more convenient to solder wires with a soldering iron if you hold them with pliers. The only thing is that the tool should be miniature, with thin handles and jaws. In principle, you can use tweezers, but it is advisable to put a heat-shrink tube on the top of it (where you hold it with your fingers) - the steel also heats up quickly. Pliers - to hold the wires
Alcohol may be required to wash off the flux, and electrical tape or heat-shrinkable tubes of various diameters for insulation. These are all the materials and tools without which soldering wires with a soldering iron is impossible.
The entire technology of soldering wires with a soldering iron can be divided into several successive stages. All of them are repeated in a certain sequence:
- Training of conductors. When soldering wires, they are freed from insulation. After this, the oxide film is removed from them mechanically. You can use a small piece of fine-grit sandpaper. The metal should shine and be light.
- Tinning. Heat the soldering iron to the melting temperature of the rosin (it begins to actively melt when touched). Take a conductor, bring it to a piece of rosin, heat it with a soldering iron so that the entire stripped part of the wire is immersed in rosin. Then take a drop of solder onto the soldering iron tip and spread it over the treated part of the conductor. The solder spreads quickly, covering the wire with a thin layer. To make it distributed faster and more evenly, the wire is turned slightly. After tinning, copper conductors lose their redness and become silvery. This is how all wires that need to be soldered are processed. Tinning the wires
- The tinned conductors are folded together, straightening them with your fingers so that they fit snugly against each other. If the soldering needs to be long, you can twist it. Holding the conductors, take solder onto the tip, press it to the soldering site, applying some force. At the same time, the soldering area heats up, the rosin begins to boil, and the solder spreads. When it covers the entire area and flows between the conductors, we can consider that soldering the conductors with a soldering iron is completed. They are held motionless for some time - until the solder cools down (to speed up the process, they blow on this place).
That's all. In the same way, you can solder two or more wires, you can solder a wire to some contact pad (for example, when soldering headphones, you can solder the wire to a plug or to a pad on a headphone), etc.
After you have finished soldering the wires with a soldering iron and they have cooled down, the connection must be insulated. You can wrap electrical tape, put it on, and then heat up the heat shrink tube. When it comes to electrical wiring, it is usually recommended to first screw on a few turns of electrical tape, and then put a heat-shrinkable tube on top, which is heated.
Differences in technology when using flux
If active flux is used rather than rosin, the tinning process changes. The cleaned conductor is lubricated with the compound, and then heated with a soldering iron with a small amount of solder. Further everything is as described.
Soldering twists with flux - faster and easier
There are also differences when soldering twists with flux. In this case, you can not tin each wire, but twist it, then treat it with flux and immediately start soldering. The conductors don’t even need to be cleaned—the active compounds corrode the oxide film. But instead, you will have to wipe the soldering areas with alcohol to wash away the remnants of chemically aggressive substances.
Features of soldering stranded wires
The soldering technology described above is suitable for monocores. If the wire is multi-core, there are nuances: before tinning, the wires are untwisted so that everything can be dipped in rosin. When applying solder, you need to make sure that each wire is covered with a thin layer of solder. After cooling, the wires are twisted into one bundle again, then you can solder with a soldering iron as described above - dipping the tip into solder, heating the soldering area and applying tin.
When tinning, multi-core wires must be “fluffed”
Is it possible to solder copper wire to aluminum
Aluminum cannot be combined directly with other chemically active metals. Since copper is a chemically active material, copper and aluminum are not joined or soldered. The point is too different thermal conductivity and different current conductivity.
When current passes, aluminum heats up more and expands more. Copper heats up and expands much less.
Constant expansion/constriction to varying degrees leads to the fact that even the best contact is broken, a non-conducting film is formed, and everything stops working. That's why copper and aluminum are not soldered.
If there is such a need to connect copper and aluminum conductors, make a bolted connection. Take a bolt with a suitable nut and three washers. At the ends of the connected wires, rings are formed according to the size of the bolt. Take a bolt, put on one washer, then a conductor, another washer - the next conductor, a third washer on top and secure everything with a nut.
Soldering iron for soldering twisted wires
Aluminum and copper conductors cannot be soldered
There are several other ways to connect aluminum and copper lines, but soldering is not one of them. You can read about other methods here, but bolted is the simplest and most reliable.
Source: https://rem-serv.com/pripoy-dlya-payki-provodov-kakoy-vybrat/
How to choose a flux for soldering
The most important element when repairing any equipment is soldering. Solder, fluxes, solder paste - all this must be taken into account when performing repair work. If everything is relatively clear with solder - usually tin-lead solders with different melting temperatures are used for this (depending on the composition of the alloy), then what about flux? What is it for?
The main purpose of flux is to remove oxides from the surface, as well as to reduce surface tension in order to improve the spreading of solder. In addition, soldering flux serves to protect the joint from environmental influences.
What types of fluxes are there?
Based on their effect on metal surfaces, fluxes are of the following types.
- Active (also called acidic). They contain hydrochloric acid, fluoride and chloride metals. Active soldering flux intensively dissolves the oxide film formed on the metal surface, thereby ensuring high mechanical strength of the future joint. It should be remembered that active flux is not suitable for repairing electrical equipment, since its residues will corrode the soldering area over time.
- Acid-free. These include rosin, as well as fluxes prepared on the basis of rosin with the addition of turpentine, alcohol or glycerin. Acid-free soldering flux not only cleans the metal surface of oxides, but also protects it from further oxidation. In addition, the use of rosin does not cause corrosion of the surface. Typically used when soldering copper, bronze and brass products.
- Activated. They are prepared from rosin, to which phosphorus or aniline hydrochloride, salicylic acid and diethylamine hydrochloride are added in small quantities. Activated soldering flux can be used for a wide variety of metals and alloys (iron, copper, nickel, bronze, nichrome, silver, steel). It can also be used for soldering oxidized copper alloy parts without pre-cleaning them.
- Anti-corrosion. These fluxes are made from phosphoric acid with the addition of various solvents and organic compounds. In addition, some of these fluxes may contain organic acids. Anti-corrosion flux is used for soldering copper and its alloys, as well as silver, platinum and constantan.
- Protective. These include olive oil, wax, petroleum jelly, powdered sugar. Protective fluxes do not have a chemical effect on the metal and also protect the cleaned surface from oxidation.
In addition, for soldering products made of cast iron, carbon steel, as well as copper and its alloys, borax (sodium tetraborate), which is a white crystalline powder with a melting point of 741 ° C, is used.
Also, borax (more precisely, its mixture with boric acid in a 1:1 ratio) is used for soldering stainless steel and hard heat-resistant alloys.
A mixture consisting of equal parts of table salt and calcium chloride is used as a flux for brass products.
To solder aluminum products, you need a flux that has a low melting point. Typically, flux for soldering aluminum contains from 30 to 50% potassium chloride.
Soldering flux can come in powder, liquid or paste form. In addition, there are special solder pastes that contain solder particles along with flux.
What is important to know when performing soldering
When choosing a flux for soldering, you take into account not only what material the parts to be soldered are made of, but also what kind of solder is used. The melting temperature of the flux should not exceed the melting temperature of the solder.
Regardless of the type of flux used, after finishing work, the soldering area must be wiped with a cloth soaked in acetone or rectified alcohol. Then clean this area with a brush or brush moistened with any solvent to remove any remaining flux. This is especially true for active flux, since its decomposition products not only contaminate the soldering area, but are also a source of corrosion.
Source: https://FB.ru/article/123292/kak-vyibrat-flyus-dlya-payki/amp
Solders
Radio electronics for beginners
At the beginning of their amateur radio activities, many novice radio amateurs rarely ask themselves about the types of solders and what their properties are.
To assemble the simplest homemade devices, the most common POS-61 or similar is sufficient. As they say: “It would be something to solder with”
You don't even have to buy solder. It is enough to take an old printed circuit board from some electronic device and assemble it with a heated soldering iron tip from the soldered contacts.
This method of “extraction” is especially relevant for those who live far from cities and large populated areas, where there is no opportunity to visit a radio store.
Solder collected from printed circuit boards
But still, solder to solder is different. In his practice, a person dealing with electronics must understand the issue of his choice. Therefore, we will consider in detail what types of solders there are, what they are used for, which one is better to use for installing electronic circuits and repairing household radio equipment.
What types of solders are there?
Solders are divided into soft (low-melting) and hard. For the installation of radio equipment, low-melting ones are used, i.e. those whose melting temperature ranges from 300 to 4500C. Soft solders are inferior in strength to hard solders, but they are used for assembling electronic devices.
Solder is an alloy of metals. For low-melting solders, this is usually an alloy of tin and lead. It is these metals that make up the majority of the alloy. Alloying metals may also be present in it, but their quantity in the composition is small. Impurities of other metals are introduced into the alloy to obtain certain characteristics (melting point, ductility, strength, corrosion resistance).
The most widely used type of solder is POS (Tin-Lead Solder). Next, a brief designation of its brand is followed by a number that shows the percentage of tin in it. So POS-40 contains 40% tin, and POS-60, respectively, 60%.
It happens that solder of an unknown brand comes into use. Its composition can be roughly assessed by indirect signs:
- Solders of the tin-lead group have a melting point of 183 – 2650C.
- If the solder has a bright metallic sheen, then it has a fairly high tin content (POS-61, POS-90). And, conversely, if it is dark gray in color and the surface is matte, then this indicates a high lead content. It is lead that gives the surface a peculiar grayish tint.
- Solders containing a lot of lead are very ductile. For example, a solder rod with a diameter of 8 mm. with a high lead content (POS-30, POS-40) is easily bent by hand. Tin, unlike lead, gives the alloy strength and rigidity. If there is a lot of tin in the alloy, then it will no longer be possible to bend such a rod easily.
POS-40 (bar)
Let's consider the purposes for which solders of the tin-lead group (POS) are used.
- POS-90 (Sn 90%, Pb 10%). Used for repairing food utensils and medical equipment. As you can see, it contains a small lead content (10%), which is quite toxic and its use in things that come into contact with food and water is unacceptable.
- POS-40 (Sn 40%, Pb 60%). Mainly used for soldering electrical equipment and parts made of galvanized iron, used for repairing radiators, brass and copper pipelines.
- POS-30 (Sn 30%, Pb 70%). It is used in the cable industry, and is also used for tinning and soldering zinc sheets.
- And finally, POS-61 (Sn 61%, Pb 39%). Same as POS-60. I don't think there's much difference between them.
POS-61 is used for tinning and soldering printed circuit boards of radio equipment. It is mainly used as a material for assembling electronics. Its melting point starts at 1830C, and complete melting is achieved at a temperature of 1900C.
Soldering with such solder can be done using a conventional soldering tool without fear of overheating of the radioelements, since its complete melting is achieved already at 1900C.
POS-30, POS-40, POS-90 completely melt at temperatures of 220 – 2650C. For many radio-electronic components, this temperature is subcritical. Therefore, it is better to use POS-61 for assembling homemade electronic devices.
A foreign analogue of POS-61 can be considered Sn63Pb37 (63% tin, 37% lead). It is also used for soldering radio equipment and for making homemade electronics. Radio amateurs choose it as an alternative to the domestic POS-61.
As a rule, any solder is sold in coils or tubes of 10 ~ 100 grams. The composition of the alloy is indicated on the packaging, for example, like this: Alloy 60/40 (“Alloy 60/40” - also known as POS-60). It has the shape of a wire of different diameters (from 0.25 to 3 mm).
It is also not uncommon that it contains flux (FLUX), which fills the core of the wire. flux is indicated as a percentage (usually from 1 to 3.5%). This form factor is very convenient. During operation, there is no need to separately supply flux to the soldering area.
One of the varieties of POS solders is POSSu . Yes, if you say it out loud, it doesn’t sound very presentable.
But, despite this, tin-lead solder with antimony (this is how the abbreviated designation stands for) is used in the automotive industry, in refrigeration equipment, for soldering the windings of electrical machines, elements of electrical equipment, winding parts and cable products. Well suited for soldering galvanized parts. In such an alloy, in addition to lead and tin, there is from 0.5% to 2% antimony.
| Solder | Initial melting t0 (Solidus) | Full meltdown (Liquidus), t0 |
| POSSu-61-0.5 | 183 | 189 |
| POSSu-40-2 | 185 | 229 |
| POSSu-40-0.5 | 183 | 235 |
| POSSu-30-2 | 185 | 250 |
| POSSu-30-0.5 | 183 | 255 |
As we can see from the table, POSSu-61-0.5 solder is most suitable for replacing POS-61, since it has a complete melting temperature of 1890C.
It is worth noting that there is also a completely lead-free tin-antimony solder POSu 95-5 (Sn 95%, Sb 5%). Its melting point is 234 – 2400C.
Low temperature solders
Among the solders, there are also those that are designed specifically for soldering components that are very sensitive to overheating. The most “high-temperature” among low-temperature ones is POSK-50-18 . It has a melting point of 142–1450C. POSK-50-18 contains 50% tin and 18% cadmium. The remaining 32% is lead. The presence of cadmium in the alloy increases corrosion resistance, but also makes it toxic.
Next in decreasing melting temperature is the ROSE alloy (Sn 25%, Pb 25%, Bi 50%). Marked as POSV-50 . Its melting point is lower than the boiling point of water and is 90 – 940C. It is designed for soldering copper and brass. In the composition of the ROSE alloy, tin occupies 25%, lead – 25%, bismuth – 50%. The percentage of metals in the alloy may vary slightly. Usually indicated in the “Composition” column on the packaging.
This alloy is very popular among radio mechanics and, in general, among all electronics engineers. It is used for dismantling/installing elements sensitive to overheating. Among other things, this alloy is ideal for tinning copper tracks of a newly manufactured printed circuit board.
Finds application in protective fuses that can be found in any radio equipment.
An even lower temperature alloy is WOOD (Sn 10%, Pb 40%, Bi 40%, Cd 10%). Its melting point is 65 – 720C. Since the WOOD alloy contains cadmium (10%), it is toxic, unlike the ROSE alloy.
It is worth noting that ROSE and WOOD alloys are quite expensive.
Solder paste
Source: https://go-radio.ru/solder.html
Solder for soldering. Types of solders and fluxes
One of the main elements of electrical and radio installation work is soldering. The quality of soldering is largely determined by the ability to choose flux and solder for soldering. To facilitate this choice, the article provides brief information about hard and light solders and fluxes, their use and their manufacture.
Soldering is the joining of hard metals using molten solder, which has a melting point lower than the melting point of the base metal. The solder should dissolve the base metal well, spread easily over its surface, and well wet the entire soldering surface, which is ensured only if the wetted surface of the base metal is completely clean.
To remove oxides and contaminants from the surface of the metal being soldered, to protect it from oxidation and to provide better wetting with solder, chemicals called fluxes are used.
Solder for soldering is a low-melting alloy of metals intended for connecting wires, leads, parts and assemblies by soldering.
Previously, solders were designated by three letters - POS (tin-lead solder), followed by a two-digit number showing the tin content as a percentage, for example POS-40, POS-60. The best solder is pure tin. However, it is expensive and is used in exceptional cases.
During radio installation, tin-lead solders are often used. In terms of soldering strength, they are not inferior to pure tin. Such solders melt at a temperature of 180 - 200 ° C.
Selecting solder for soldering
The choice of solder is made depending on the following factors:
- metals or alloys to be joined
- soldering method
- temperature restrictions
- part size
- required mechanical strength
- corrosion resistance, etc.
To solder thick wires, use solder with a higher melting point than for soldering thin wires. In some cases, the conductivity of the solder must also be taken into account (reminder: the resistivity of tin is 0.115 ohm x mm2/m, and that of lead is 0.21 ohm x mm2/m).
Solder for soldering is divided into three groups: refractory, low-melting and ultra-low-melting.
Refractory solders (radio amateurs practically do not use them). Refractory solders include solders with a melting point above 500 °C, which create very high mechanical strength of the joint (tensile resistance up to 50 kg/mm2).
Their disadvantage is precisely that they require high heating temperatures and, although the strength of such soldering is very high, intense heating can lead to undesirable consequences: you can, for example, “release” a steel part.
The disadvantage of hard solders is that they require high heating temperatures, and although the strength of such soldering is very high, intense heating can lead to very undesirable consequences: you can overheat an expensive part and damage it (for example, a transistor or microcircuit), you can “let go” ", for example, a steel part (spring).
Low-melting (ham radio) solders. This category includes solders with a melting point of up to 400 °C, which have relatively low mechanical strength (tensile strength up to 7 kg/mm2). In radio engineering installation work, low-melting solders are mainly used. They contain tin and lead in various proportions, for example, POS-61 solder, which contains 61% lead, 38% tin and 1% various additives.
Ultra-low-melting (ham) solders. There are also alloys that contain, in addition to tin and lead, bismuth and cadmium. These alloys are the most fusible: some of them have a melting point of less than 100 °C. The mechanical strength of the connection of such alloys is very low.
Previously, they were used for soldering crystals in crystal detectors. Currently, low-melting cadmium-bismuth alloys are used in the repair of printed circuit boards.
They are also used for soldering transistors, since according to technical specifications it is recommended to solder them with solder with a melting point not exceeding 150 °C.
For soldering transistors, you can use the so-called Wood's alloy with a melting point of 75 ° C, which contains: tin - 13%, lead - 27%, bismuth - 50%, cadmium - 10%. Wood's alloy can be prepared according to the specified recipe yourself or purchased at a pharmacy. Soldering is carried out with a weakly heated soldering iron. Rosin is used as a flux.
Amateur radio solder for soldering
Nowadays, solder wire with a cross-section of 1 to 5 mm is used for soldering. The most common are 1.5-2 mm multi-channel solders.
Multi-channel means that inside the tin wire there are several channels of flux, which ensures the formation of an even, shiny and reliable solder.
Such solder is sold in coils - at radio markets, in flasks - in which it is rolled into a spiral, and in reels (the amount of solder in them is such that it will last for more than one year). It is recommended to purchase it in the form of a wire, the thickness of a match - it is more convenient to solder.
When soldering installation wires of radio equipment, it is convenient to use tin-lead solders, cast in the form of thin rods with a diameter of 2 - 2.5 mm. You can make such rods yourself by pouring molten solder into a vessel with a hole pre-made in the bottom. The vessel should be held above a sheet of tin or a metal plate. After cooling, the rods should be cut into pieces of the required length.
Modern solders used in soldering electronic circuits are produced in the form of thin tubes filled with a special resin (colophonium), which acts as a flux. The heated solder creates an internal bond with metals such as copper, brass, silver, etc.
, if the following conditions are met: the surfaces of the parts to be soldered must be cleaned, that is, the oxide films formed over time must be removed from them, the part at the soldering site must be heated to a temperature exceeding the melting point of the solder.
Certain difficulties arise in the case of large surfaces with good thermal conductivity, since the power of the soldering iron may not be enough to heat it.
Making your own solder for soldering
To independently prepare solder, the components of the composition (tin and lead) are weighed on a scale, the mixture is melted in a metal crucible over a gas burner and, after mixing the melt with a steel rod, the slag film is removed from the surface of the melt with a steel plate. Then the melt is carefully poured into molds - troughs made of tin, duralumin or gypsum. Melting must be performed in a well-ventilated area, wearing safety glasses, gloves and an apron made of coarse fabric.
Why do you need flux when soldering?
During soldering, the temperature of the parts being connected increases significantly. At the same time, the rate of oxidation of metal surfaces increases. As a result, the solder wets the parts being joined worse. Therefore, it is necessary to use auxiliary substances and fluxes.
What is flux?
Flux is an auxiliary material that is designed to remove the oxide film from parts being soldered during soldering and ensure good wetting of the surface of the part with liquid solder. Without flux, solder may not adhere to the metal surface.
Purpose of fluxes: reliably protect the surface of the metal and solder from oxidation, improve the conditions for wetting the metal surface with molten solder.
The effect of a flux depends on its composition; available fluxes either dissolve oxide films on the surface of the metal (and sometimes the metal itself), or protect the metal from oxidation when heated. Thus, the flux forms a protective film over the soldering area.
Soldering fluxes
Flux is already contained in modern solder in the form of a thin core. When solder melts, it is distributed over the surface of the liquid metal. The surfaces of already tinned metals are also coated with flux before joining them (actually soldering). In this case, flux is a surfactant, that is, a Surface Active Substance. After the parts come into contact, excess flux between them comes out and evaporates all the time because its evaporation temperature is lower than that of solder.
Fluxes are different. For example, to repair metal utensils, they use “soldering acid” - a solution of zinc in hydrochloric acid. You cannot solder radio structures with this flux - over time it destroys the soldering. For radio installation, it is necessary to use fluxes that do not contain acid, for example, rosin.
Requirements for amateur radio fluxes
The choice of flux is an important issue. Previously, only rosin was used, there was no other flux. Why rosin is bad - rosin, alcohol rosin flux belong to the category of active fluxes. The first disadvantage is that at high temperatures, not only the metal oxide is removed, but also the metal itself.
The second drawback is that cleaning the board after soldering with rosin is a big problem. You can only wash off the residue with alcohol or solvents (and even then, sometimes it’s easier to pick it out with something sharp). Flux residues on the board are not only unsightly from an aesthetic point of view, but also harmful.
On boards with small gaps between conductors, the growth of dendrites (in other words, short circuits) caused by galvanic processes on a contaminated surface is possible.
What is the solution - on the modern materials market you can find a wide range of fluxes that are washed off with ordinary water, do not destroy the soldering iron tip and provide high quality soldering. Such fluxes are usually sold in syringes, which is very convenient for use.
How to replace flux
Regardless of what flux is used, the finished soldering must be wiped with a cloth soaked in rectified alcohol or acetone, and also cleaned with a stiff brush or brush moistened with a solvent to remove flux residues and dirt. In some exceptional cases, instead of rosin, you can use its substitutes:
- rosin varnish, available in hardware stores. It can be used as a liquid flux instead of a solution of rosin in alcohol. The same varnish can also be used for anti-corrosion coating of metals.
- resin - pine or spruce resin - is an accessible material, especially for amateurs living in rural areas. You can prepare this flux yourself. Resin collected from trees in the forest must be melted in a tin over low heat (the resin may ignite over high heat). Pour the melted mass into matchboxes.
- an aspirin tablet available in any home medicine cabinet. The disadvantage of this flux is the unpleasant smell of smoke released when aspirin melts.
Nowadays a large number of different so-called “no-clean” fluxes are produced, both liquid and in the form of a semi-liquid gel. Their peculiarity is that they do not contain components that cause oxidation and corrosion of the parts being connected, do not conduct electric current and do not require washing the board after soldering. Although it is still better to remove all flux residues from the soldered parts after completing soldering.
To apply liquid flux, you can use a brush, a cotton swab or just a match, but it is more convenient to use the so-called “flux applicator”. You can try to buy a branded flux applicator that costs about $20-30. It is also convenient to use flux in the form of a gel or paste. To apply it, you can use a disposable syringe, but because of its thickness, you will have to use a thicker syringe needle.
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Source: https://powercoup.by/stati-po-elektromontazhu/pripoy-dlya-payki
How to choose the right soldering iron and learn how to solder wires
Soldering is the primary method of electrical and mechanical joining of both parts and wiring. But despite the apparent simplicity of the process, soldering is quite complex and painstaking. That is why, before picking up a soldering iron, you need to have a good idea of what, why and, most importantly, how to solder wires.
Tools and accessories
Soldering, like any other technical process, involves the use of certain tools and accessories. You will need a few tools: a soldering iron, a knife, pliers, a file, sandpaper.
There are even fewer accessories - soldering flux and alcohol or gasoline are enough. Nevertheless, all of these are important components of the process and the choice of both must be taken extremely seriously.
Both the mechanical and electrical reliability of the soldered joint will depend on the quality of the soldering iron and the availability of the necessary accessories.
Selecting and preparing a soldering iron
This is perhaps the most crucial stage. A poorly chosen or improperly prepared tool will not produce high-quality soldering.
Power and type
The main criterion for choosing a soldering iron is its power. The industry produces instruments with power from 10 to 200 W and higher. The former can be the size of a fountain pen, the latter look like a natural hammer of impressive size.
Electric soldering irons with a power of 30 (left), 60 and 200 W.
All that remains is to decide which soldering iron to choose for soldering wires. Here everything will depend on the operation being performed, or more precisely, on the thickness and massiveness of the parts that need to be soldered. The more massive the parts, the greater the heat capacity the tool should have. An approximate dependence of the recommended soldering iron power on the task being performed can be presented in the following table:
- 15-25 W – small radio elements, microcircuits, conductors with a diameter of up to 0.3-0.5 mm;
- 30-40 W – large radio elements, wires with a diameter of up to 1 mm, including multi-core ones;
- 40-60 W – fairly large parts, conductors with a diameter of up to 2 mm;
- 100 W – massive parts, wires with a diameter of up to 3-4 mm;
- more than 100 W – power wiring with a diameter of more than 4 mm.
If you don’t have a soldering iron with the necessary characteristics at hand, you can take a slightly larger one in power, but not vice versa. With a massive device, it is possible to solder thin wires with a certain skill, but with a small and low-power thick one, it is almost never possible. Ideally, your household will have several electric soldering irons of varying power.
But what to do if there is no soldering iron of the required power or if it does not exist in nature at all? Trying to solder busbars into a pencil thick with a 100-watt soldering iron? In no case! In this situation, regular fire will help.
Place the parts prepared for soldering, for example, in the flame of a household gas burner or alcohol lamp and solder. Additional heating will help to perform high-quality soldering even with low-power tools.
The only thing is, when heating the wires over an open flame, do not overdo it - a little additional heating is enough.
Separately, it is worth noting the so-called “pistol” or pulse soldering irons, which were widely used, and even today are in service with craftsmen on the road.
A modern version of a pistol soldering iron.
At first glance, the advantages of such a device are obvious - it heats up instantly and cools down just as quickly. But this feature is convenient only for a narrow circle of specialists - on-call specialists. He came, took it out of the suitcase, poked it, put it in the suitcase, took the money and left. But anyone who has seriously worked with such soldering irons knows very well their shortcomings.
Source: https://pochini.guru/sovety-mastera/kak-payat-provoda
Do-it-yourself flux for soldering: how to prepare, use correctly, types and their features
Flux is a substance of organic or inorganic nature that ensures stable combustion of the electric arc and promotes the formation of a good welded joint. It also removes harmful impurities from the weld pool and improves the quality of the operation.
Such substances are sold in retail chains, but having several necessary components, anyone can make flux.
The soldering component is mainly used for welding thin wires and small parts when connecting elements of radio-electronic devices.
Variety of solders
To connect different types of parts, different fluxes are used, which melt at a certain temperature.
The latter must be above the melting point of the articulated metal elements, and this factor must be taken into account when performing the operation.
Fluxes differ in the following melting characteristics:
The melting point of the former is significantly higher than that of the latter. Therefore, solders are also called refractory and low-melting solders. Soft solders are used to connect thin elements, hard solders are used for thick ones.
Refractory ones transform into a liquid state of aggregation at temperatures above 400° C, which ensures reliable formation of compounds.
However, they are not suitable for installing or repairing electronic equipment, thereby causing overheating of nearby radio components. For this purpose, fusible materials are used, consisting of lead and tin, possibly other inclusions.
There are also particularly low-melting mixtures that melt at a temperature of just over 100 degrees. Their use is associated with the installation of transistor circuits.
A high-quality flux should conduct heat well, ensure the strength of articulated parts, stretch, prevent corrosion, but not melt when the temperature rises.
Store shelves provide the buyer with a large selection of soldering solders.
The latter are made in the form of ordinary wire, hollow tubes with rosin, various ribbons, etc. The most used type is tin rods with a diameter of up to 5 mm.
Multichannel fluxes, made in the form of reels and spirals, give special strength to the connection. However, for ordinary household operations, a wire version with a length of 50-70 mm, no more, is suitable.
A tube filled with colophonium resin connects the brass and silver parts.
Regardless of the type of solder used, the connection area must be wiped with a cloth moistened with acetone after the operation. The seam itself is cleaned with a small hard brush, also using the specified solvent.
Making flux
To ensure contact between radio components or thin wires, you will need a thin rod of solder with a diameter of up to 1 mm, which you can make yourself.
A small bottle or other container of the same size, but always having a flat bottom, will help to give the product the required shape. Before starting to prepare the flux, you need to make a hole in the latter with a diameter of no more than 2 mm.
Take a piece of lead or tin, melt it using a gas burner and pour the material into the prepared bottle. A stream of metal will begin to emerge through the hole and solidify, which must be laid on a hard surface.
Home craftsmen often use special devices for producing rods for unique molding, but an ordinary tin sheet will also do.
Established welding substances are being replaced by new ones in the form of gel and soft paste. They prevent oxidation processes, prevent corrosion, do not conduct electricity, and do not require post-operative cleaning.
You can also make them yourself.
Summarize
The solution is prepared according to the following algorithm:
- Crush the rosin crystals into powder with a wooden hammer.
- Mix powder with medical alcohol in a 1:1 ratio in a glass container.
- After thorough stirring, place in a hot water bath.
- Stir until smooth.
The resulting mixture can be drawn up for soldering with a medical syringe, or a bottle of nail liquid can be used.
Soldering operations are accompanied by the use of electric current and chemical active ingredients - molten fluxes, which is hazardous to health.
Therefore, it will not be superfluous to carry out work in compliance with safety precautions. Safety glasses, gloves and a respirator will prevent solder vapor poisoning, electric shock, and skin burns.
Source: https://prosvarku.info/rashodnye-materialy/flyus-dlya-pajki-svoimi-rukami
Classification of fluxes, requirements for properties, recommendations for choosing various materials for soldering
Flux is used to remove the oxide film from the metal surface during soldering. This material improves the quality of the connection and promotes better contact insulation. However, for different types of metal it is necessary to choose the right additive and become familiar with the technology of its use.
Recommendations for selection
Flux can perform several functions - protective, cleaning, soldering of metals without pre-treatment. The choice of a specific composition depends on the material of manufacture of the parts being connected, the conditions of further operation and the requirements for the speed of formation of the solder joint.
Additionally, the following parameters are taken into account:
- Melting temperature. Affects the operating mode of the soldering iron and the soldering speed.
- Boiling temperature. The critical limit after which most fluxes lose their properties.
- Material of manufacture of organic or inorganic type. The former are hygroscopic and can cause rust at the joint.
- Passive and active. The former affect the material, changing its surface or properties. The latter perform the functions of a purifier or insulator.
The determining criterion is the type of metal being soldered, the dimensions of the workpiece and the requirements for further operation.
For electrical engineering
Soldering of most electronic boards and contacts is characterized by a small size of the processed area. For such work, it is recommended to use liquid flux, without the presence of active components. A low melting temperature is important, since strong thermal effects can negatively affect the integrity of the contacts.
Recommended compositions:
- LTI-120. Suitable for silver, stainless steel, zinc. Neutral, after application excess is easily removed. Cost – 53 rubles.
- FCDT. Liquid composition, does not affect the electrical conductivity, the main components are rosin (10%) and ethyl alcohol (84%). Average price - 47 rubles.
- Flux-gel TT. Area of application: creating high-quality compounds. Has a color indicator - discoloration indicates the absence of the active component. Cost – 51 rub.
Soldering of aluminum alloys
The difficulty of working with aluminum contacts lies in the high rate of formation of the oxide film. Therefore, it is necessary to use flux brands with highly active components. They quickly remove the natural insulator from the metal surface and prevent its further appearance until a reliable connection is formed.
Optimal brands:
- F 38N PET. It contains the most active components; sometimes it needs to be diluted with ethyl alcohol. Price – from 60 rub.
- Special for aluminum. This is a no-clean composition that can later be removed with a rag. Has average performance indicators. Cost – 48 rubles.
- FIM PET. The composition includes phosphoric acid, which quickly corrodes the oxidizing film. The optimal type of flux for soldering aluminum at home. Cost - from 54 rubles.
Another advantage of these grades is the possibility of using them for soldering work with stainless steels. But before that, you need to read the instructions for the specific type of flux.
Connecting copper parts
The technology for soldering copper parts is standard; the use of additional materials is only necessary for special alloys with specific properties. It is important to first clean the surface of dirt and insulation. The application technology is standard; the volume and time of exposure depend on the characteristics of the contact.
Recommended compositions:
- Soldering acid PET. Used for soldering nickel, its alloys, copper and materials with similar properties. Easy to apply, price - from 53 rubles.
- Borax. Recommended for high-temperature soldering and characterized by optimal performance. Cost – from 44 rubles.
- LTI-120. Liquid consistency, has no active ingredients, contains alcohol, rosin, hydrochloric acid diethylamine. Price - from 61 rub.
To carry out the work correctly, it is necessary to prepare the place; if flux evaporation causes the appearance of unpleasant or hazardous gas, provide forced ventilation.
The video provides an overview of popular types of flux:
Source: https://ismith.ru/welding/flyus-dlya-pajki/
Flux for soldering copper
Reading time: 4 minutes
Soldering copper with your own hands is a simple process that even beginners can handle. The post soldering technology is understandable; it does not require many years of experience and professional skills. This is why working with copper is so popular among home craftsmen.
But it is not enough for you to know soldering technology alone to achieve decent quality connections. It is important to know how to use the tool and choose the right flux for copper. Flux improves the strength of the connection, protects the soldering area from external factors and, in general, allows you to obtain connections of the best quality. In this article we will briefly describe how to choose a flux for copper soldering and how to use it in your work.
Types of fluxes
Fluxes are divided according to two characteristics: chemical composition and consistency. Let's start with the chemical composition.
Chemical composition
There are 3 types of fluxes: anti-corrosion with phosphorus, salicylic acid-based fluxes and boric acid-based rosin/flux. Let's look at each type in more detail.
Anti-corrosion fluxes are made from phosphorus and solvents. Such fluxes make it possible to obtain a compound that is resistant to the formation and spread of corrosion. Also, this type of flux does not need to be removed after soldering, which saves time. Anti-corrosion fluxes are acidic.
The second type of acid flux is a flux based on salicylic acid with the addition of technical petroleum jelly. Such fluxes are also called VTS. The resulting connections are neat and aesthetic. The soldering itself is clean; there is no need to further clean the metal.
Most often used for electrical installation work.
The last type of flux is acid-free rosin. It can be used for soldering electrical appliances and for working with pipes. Keep in mind that rosin has low chemical activity.
Therefore, its use requires careful preparation of parts before soldering.
For soldering work, either ordinary rosin is often used (it is also called natural), or its solutions in alcohol (this includes CE flux, for example).
Rosin can improve the spreading of solder during soldering, distributing it evenly along the junction of two workpieces. Also, molten rosin can dissolve oxides, thereby protecting the soldering area and improving the quality of the connection.
Consistency
Flux for soldering copper is available in liquid, paste and dry form. We recommend using paste fluxes, since they are very convenient to work with when soldering copper pipes. Dry fluxes are absolutely unsuitable for such work, and liquid fluxes do not always achieve the desired result.
Pay attention to the consistency. It should be homogeneous, without lumps or foreign inclusions. If you use low-quality flux in your work, the result of the work done will be unsatisfactory.
Features of application
First of all, decide on the type of soldering work. After all, the technology for soldering copper wires and for soldering copper pipes will be different. We will talk about soldering copper pipes, since flux is required for such work.
Let's start with the tool. You will need a quality soldering iron, a metal knife or pipe cutter, a chamfer, a wire brush, a pipe expander, a hammer and a tape measure. Take the part and cut the pieces to the required size using a pipe cutter or metal knife.
Then clean the edges of the pipe using a wire brush. There should be no traces of dirt, oil, dust, paint, etc. on the metal surface. Take a pipe expander and expand the edge of one of the blanks. This way you can connect one pipe to another.
Now the flux. As we said earlier, it is better to use paste flux. Apply it to the ends of the workpieces in the place of future soldering. Can be applied using a brush or fingers. Insert one pipe into the other. The workpieces must fit tightly together and squeeze out excess flux. Remove them with a rag.
Source: https://svarkaed.ru/rashodnye-materialy/flyus-i-svarochnaya-provoloka/flyus-dlya-pajki-medi.html
Choosing the best flux for soldering BGA (Ball grid array) chips
In this article we will try to answer questions related to the selection of soldering flux in the case of soldering integrated BGA microcircuits and their reballing (rolling ball leads).
About bga chips
The use of housings with pins in the form of balls, instead of the usual pins, has now become the only alternative in micro and radio electronics.
Chip with BGA pins
Of the main advantages of using microcircuits of this configuration, we note:
- saving space on the board;
- small pickups;
- thermal conductivity, with the exception of elements of motherboards and computer video cards.
Disadvantages include: inflexibility of the leads, complexity of installation and the need for additional x-ray control after installation of these microcircuits.
Flux requirements for bga soldering
The main task of this soldering material during the soldering process, in particular, bga elements, is the removal of metal oxides and oxide films at the stage of preparing the soldering area.
A high-quality flux should provide better spreading of solder (reduced surface tension) and prevent re-oxidation of the prepared surface.
The operating temperature of the flux must be lower than the melting temperature of the solder that makes up the terminals of the microcircuit.
In the case of using a chip with tin-lead leads, the liquidus (full melting temperature) mostly starts from 179ºC.
Soldering flux applied to the board
The flux should start working at a temperature an order of magnitude lower. So that during complete melting of the solder all oxides are removed from the soldering area.
It is worth adding to the fundamental requirements that the flux should not boil and emit carcinogenic fumes.
Easy removal of flux residues or no need for cleaning is a property that experts consider a “must have”, recently, when soldering microcircuits with ball leads.
Ideally, the flux should completely evaporate by the time the microcircuit is soldered; in extreme cases, it should be a dielectric and chemically inert in its composition.
In the case of reballing, the requirements for ease of rinsing are usually less stringent, since it is much easier to rinse off the flux using a cleaning fluid with open access to the soldering area.
Examples of fluxes intended for soldering BGA chips
How to choose a soldering flux for mounting and reballing bga chips? Below we provide examples of materials that meet most of the characteristics listed in the article. They were also tested in combat mode and proved their suitability in practice.
Flux KOKI TF-M955 (NO-CLEAN) “Classic”
High quality flux for repair and soldering.
Has transparent residues that do not interfere with quality control. Halogen free. For dispensers or brush application. It is a yellowish paste with a viscosity of 6600±10% mPa.s. The declared shelf life without loss of properties is 12 months at temperatures below 10ºC.
Flux KOKI TF-A254 (NO-CLEAN) “Easy to clean”
Adhesive flux TF-A254 is indispensable for soldering and reballing BGA microcircuits in phones, laptops and other electronic digital devices, as well as when working with other SMD components. TF-A254 flux must be washed using cleaning fluids. Vigon® is recommended.
The unique technological properties of TF-A254 flux allow soldering even in conditions where the preheating was short, as a result of which the required heating level was not achieved.
Source: https://www.mettatron.ru/stati/payalnye-materialy/vybiraem-luchshij-flyus-bga-chipov
