What flux is better to solder microcircuits. Types of solder and flux. Requirements for radio amateur fluxes

Soldering flux is an auxiliary substance, the use of which helps to clean the surfaces of the connected metal elements from oxidation. When resorting to soldering without the use of flux, you should not count on high-quality work performance and reliable fastening of the necessary parts. Therefore, before starting work on connecting parts with a soldering iron, it is necessary to select a good, high-quality flux.

Purpose

Fluxes are used primarily to remove all kinds of contaminants from the metal surface. Moreover, when soldering joints, they protect the heated solder from oxidation. This, in turn, contributes to the flowability of the solder and, accordingly, the improvement of the quality of the solder.

A good soldering flux can only be selected based on the nature of the metal joints and the solder alloy. The remains of any fluxes, regardless of their type, must be removed from the joints after the work is done, since they themselves contaminate the metal and can lead to the development of corrosion processes.

Types of soldering fluxes

Conventionally, fluxes are divided into two main categories - oxidizing and reducing. Also, depending on the need to perform certain tasks, fluxes are isolated for metal melting, welding, electrolysis, growing single crystals, soldering non-ferrous and jewelry alloys.

In general, according to the effect that is exerted on the metal during soldering, the following fluxes are distinguished:

• active (acidic);
• acid-free;
• anti-corrosion;
• activated;
• protective.

Active fluxes

Such soldering flux often contains hydrochloric acid, fluoride and chloride metals. The action of active fluxes involves the active dissolution of oxide films on the surface of metal parts. Due to these properties, the maximum mechanical strength of the resulting joints is ensured.

Despite their wide distribution, active fluxes are not suitable for use in the installation and soldering of electrical equipment, because their remnants quickly corrode the junction of parts.

Acid-free fluxes

An acid-free soldering flux, commonly known as rosin, is a substance made from alcohol, glycerin and turpentine. When the soldering iron is heated to a temperature of more than 150 ° C, the use of such a flux makes it possible to dissolve the oxides of lead, copper, tin, reliably cleaning the metal surfaces.

The main advantage of rosin-like flux is the absence of the effect of separation of the surfaces to be joined during soldering. Such a flux is actively used for brazing copper, bronze, brass.

Activated fluxes

This type of flux is prepared on the basis of phosphoric or hydrochloric aniline, diethylamine or salicylic acid. This option is applicable for brazing a variety of metals and alloys, such as iron, copper, steel, nickel, zinc, silver, as well as copper parts without the need for preliminary cleaning.

Anti-corrosion fluxes

Based on the definition itself, it is easy to guess that anti-corrosion flux is used for soldering most often when it is necessary to connect parts that are potentially susceptible to the development of corrosion processes.

The composition of the anti-corrosive soldering flux includes the use of petroleum jelly, salicylic acid, triethanolamine and ethyl alcohol. Despite its main purpose, this type of flux requires careful removal of its residues upon completion of soldering by wiping the parts with acetone or alcohol.

Protective fluxes

Since no destructive chemical effect on metals occurs during use, a protective flux can be used for soldering microcircuits. Like the bulk of other types of fluxes, such substances protect previously cleaned metal surfaces from oxidation. The category of protective fluxes includes, first of all, petroleum jelly, wax, powdered sugar, olive oil, and other substances with low chemical activity.

Storage

The most common alcohol-based fluxes are usually liquid in consistency. Therefore, they need to be stored in a carefully sealed, sealed container. Otherwise, there is a loss of their basic properties and even complete evaporation.

Soldering flux paste also needs to be stored in a closed container. Optimal conditions for such a flux are a low-level room. Despite the fact that the paste does not absorb moisture from the environment, there is a risk of moisture condensation on the walls of the container and nearby surfaces.

It is recommended to store flux gel for soldering away from flammable substances, objects and sources of open fire, since most fluxes in this category are highly flammable. In this case, the storage temperature should be at least 10 and not more than 25 degrees Celsius.

Flux application

When soldering, the joints are well cleaned, covered with flux and heated with a soldering iron. At the application site, the flux begins to foam and smoke. At this point, a small amount of solder must be applied to the tip of the soldering iron, which will subsequently cover the surfaces to be joined.

Probably, you shouldn't talk about the properties and advantages of using fluxes for soldering. It is enough just to take a soldering iron and try to connect the parts without flux. In this case, the soldering process will turn out to be really long, and the result is frankly of poor quality, since the solder will be too unreliable to fix on the surface to be soldered.

How to prepare a do-it-yourself soldering flux?

The simplest option for self-preparation of a flux is to use a rosin-alcohol base. To begin with, rosin powder is poured into the container, after which it is poured with an alcohol solution. After a while, the alcohol will evaporate and the flux acquires a moderately thick consistency, convenient for applying the substance to metal parts during soldering.

Acetylsalicylic acid dissolved in a little water, acetone or alcohol can be used as a self-prepared flux suitable for tinning steel and copper surfaces. It is convenient to store such a liquid flux in a container from varnish, using a lid with a brush when applying.

How to choose the right flux?

According to avid radio amateurs who are well versed in soldering, choosing the right flux is almost one hundred percent guarantee of successful work. Here, first of all, one should focus on the material of the parts to be joined, as well as the nature of the soldering.

For soldering radio components, copper parts and wires, it is advisable to use inactive rosin-based fluxes. These fluxes are a modified version of conventional rosin by adding a number of constituents known as activators.

Inactive fluxes have improved antioxidant properties. Due to the paste or liquid state, such fluxes can be applied directly to circuit boards or soldering points of metal joints. This flux is ideal for brazing aluminum. Additionally, it is worth noting their wide availability and relatively low cost.

As for medium-active fluxes, it is advisable to use them for soldering the most delicate contacts, for example, during repair mobile phones and other modern portable devices. For this, fluxes are suitable that do not foam or boil during operation, have minimal corrosiveness, and are also easily applied to boards.

Medium active fluxes are often used by craftsmen service centers for the repair of digital mobile devices... They are usually used to solder the smallest microcircuits. Moreover, they are suitable for use not only with lead, but also with lead-free solders.

The most versatile are gel fluxes. They can be used for almost any type of soldering. Gel-like flux is especially effective for brazing aluminum, copper, and other common materials using lead solders.

Finally

Correct selection of suitable Supplies when performing soldering, it is a guarantee of a well-performed work. Beyond the choice good flux a choice of solder, nozzles for a hair dryer, a soldering iron tip, etc. is required.

Even using the most advanced soldering stations in the work in the presence of an unsuitable flux, solder or tip, as a result, you can get a completely different result than you intended. Enough water has flowed under the bridge since the time when specialists actively used classic soldering irons with a power of up to 60 W with a homemade, filed copper tip, as well as ordinary rosin as a flux. At present, the use of such a material and technical base turns out to be extremely ineffective.

Soldering of parts and products using special reagents called fluxes is widespread in a wide variety of industries.

In this case, the main purpose of the flux is to ensure the ideal spreading of the solder over the surface of the soldered joint and to create conditions for its reliable adhesion to metal products. In other words, in most cases, soldering cannot be done without flux, they are needed to comply with the technology.

When considering what the flux is for when soldering materials, any additional explanation may be considered superfluous.

For a complete understanding of the scope and features of work, it is necessary to familiarize yourself with the known types of fluxes used in practice.

In accordance with their main purpose, as well as the degree of impact on the connected products, all flux compositions for soldering are divided into the following categories:

• inactive or neutral fluxes that do not contain acids and are practically non-conductive;
• active or acidic flux reagents prepared on the basis of hydrochloric acid;
• protective (anti-corrosion) fluxes, allowing to protect the contact zone of the soldering of the ready-made joint from rust and destruction.

And the well-known drill flux is used in the form of a powder, and is needed for brazing copper pipes. Solder paste - a mixture of solder and flux - is needed for surface mounting of parts on boards.

Neutral substances

Neutral fluxes include rosin, which is recommended for soldering small radio-technical components and microcircuits.

This popular reagent is needed in order to solder parts of copper and its alloys of dissimilar structure at relatively low heating temperatures of the joint (no more than 450 degrees). Moreover, this operation is permissible even if there are thin oxide films on the surface of the workpieces.

Due to their low activity, rosin-based fluxes provide protection of products against corrosion and are therefore in high demand.

When preparing the working composition, alcohol, glycerin or turpentine are added to the rosin crushed to a powdery state, which improves the quality indicators of the mixture.

Neutral flux gels are sold, which are needed for lead-free soldering of microcircuits. It is convenient to apply them with a special dosing syringe.

Active and anti-corrosion

Active fluxes are also often made on the basis of rosin, brought to a powdery state. However, in this case, in the composition of the prepared mixture in small volumes contains organic compounds (acidic or amine).

Thanks to this, with its help, it is possible to solder not only copper parts to the metal base, but also silver, nickel and steel products or blanks.

In more difficult brazing conditions, active fluxes based on hydrochloric acid with the addition of zinc chloride, obtained as a result of a simple substitution reaction, are needed.

This type of flux additive is well known to professionals: it is most often produced and sold under the name "soldering acid". Acidic fluxes are needed for brazing aluminum parts.

The scope of this class of flux is the sealing of copper and silver products. They are also needed for brazing steel billets and various alloys.

Since these reagents belong to the category of chemically active compounds, soldering with their use makes it possible to more effectively deal with oxide films. This activity provides a more intense interaction with the base metal from which the alloyed workpieces are made.

Another feature of these reagents is their high electrical conductivity, which excludes the possibility of their use as an insulating protective coating.

There are compositions based on phosphoric and organic acids. Why do we need such fluxes at all?

They belong to the category of anti-corrosion and are used to remove residues and traces of rust from metal surfaces, as well as to protect against the possibility of the appearance of oxides after soldering (during operation).

Since acidic components are used in the preparation of these mixtures, they are very similar to brazing acids.

However, unlike the latter, anti-corrosion flux for brazing does not remove oxide films. It is needed to protect against damage caused by the oxidation reaction.

Application procedure

Fluxes can be in a solid (pasty) or liquid state and sold in packages by itself. of various shapes and volume.

So, solid rosin goes on sale in flat jars equipped with a tight-fitting lid.

According to the initial state of aggregation of these compositions, the following methods of their use are distinguished:

• with solid flux, during soldering, the soldering iron tip must first be dipped into the reagent body, after which a small amount of solder is captured;
• in cases where a ready-made liquid mixture is prepared or used on the basis of rosin, it is simply applied to the adhesion site using a regular brush with a soft bristle;
• when working with a pasty composition, small portions of the flux are applied to the contact site with any suitable stick for this (squeezed out of the syringe pre-filled to the required dosage).

Often in stores, rosin is sold, prepared in the form of a special gel, already placed in a syringe of a certain capacity.

Such gel-like compositions are commonly referred to as neutral reagents widely used in electronics for soldering miniature parts.

Self-cooking

For rosin-based soldering, you can do it yourself. To do this, it is enough to crush and grind it into powder, and then pour the resulting composition into a container and immediately pour a small amount of technical alcohol.

The ratio of the components used in the preparation of the flux should be three to five. After thoroughly shaking the mixture to be prepared, leave it for a couple of days and do not touch it until the rosin is completely dissolved in alcohol.

The most suitable container for liquid flux is a regular varnish bottle, the lid of which already has a built-in brush. Immediately before use, it is recommended to thoroughly wash the used bottle from the traces of varnish.

Quite often, experts use another type close to fluxes active additives called solder fat. This reagent is usually referred to as conditionally neutral compounds. They are needed to somewhat improve the conditions for soldering metal joints.

It should be recalled that before buying any brand of flux, you need to study the instructions for it, and understand what exactly it is intended for.

Only in this case it will be possible to make a high-quality soldering joint.

Rosin is an ordinary resin, after distillation, yellow or orange in color, taken from conifers. V Soviet time those who could not buy rosin in the store for some reason were offered to collect resin from conifers in the forest and heat it in a metal container over low heat, preventing ignition, pour it into matchboxes or plastic jars. This resin could be used for soldering. Fluxes are used to remove oxide film from the surface of the part to be brazed. They are soldered with EPSN type soldering irons in this way: they dip the heated tip of the soldering iron in rosin, collect some solder on the tip and transfer this solder to the place of soldering. If the gumboil is liquid, it is applied with a brush, if the gumboil is pasty, then it is applied with a stick, or if it is in a syringe, then the required amount is squeezed out to the place of soldering.

The photo above shows a can of rosin sold in stores, which was probably poured in a similar way in liquid form. There are two types of fluxes:active and neutral... On sale in stores, rosin is found not only in solid form, but also in the form of a special rosin - a gel in a syringe.

According to manufacturers, the rosin-gel is also suitable for soldering SMD parts.

Both types of fluxes, both active and neutral, must be washed off after soldering from the board. If traces of neutral flux remain on the board, the device may and will work normally, everything here depends on the conductivity of the flux.

The figure shows a brush for removing flux traces from boards. If you do not wash off the remnants of the active flux, after soldering with it, traces of active salts and other hazardous substances remain on the board, which over time can corrode the soldering or the soldered wire. In general, I recommend after soldering, when it is possible to wash the soldering point with a brush dipped in industrial alcohol or acetone.

Recently, I have been rinsing boards instead of alcohol with Aseptolin, (simply because it has already been purchased), a liquid that is sold in pharmacies. Excellent result and inexpensive. Contains 92.5% ethyl alcohol and costs only 30 rubles per 100 milliliters. The bottle lasts for a long time. There is a flux based on rosin and alcohol that is widely used. Which is called the alcohol-rosin flux, or abbreviatedSCF.

I often use the one in the photo above. Such a flux can be easily prepared by yourself, it is enough to grind the rosin into powder, pour it into a container in which it will be stored, and fill it with technical alcohol. The ratio of rosin and alcohol should be 3 to 5. After we wait one or two days, until the rosin dissolves in alcohol, and you can use it.

The photo above shows two flux storage containers that I use when soldering.Convenient to use, as a container for flux, turned out to be a bottle of nail polish, as it comes right with a brush. Previously, before use, the bottle must be rinsed from traces of varnish with acetone or solvent. With the help of alcohol-rosin flux, you can solder in places where it is simply impossible to crawl with rosin. Or those surfaces that the rosin “does not take.” For example, using SCF, you can solder wires to the terminals of batteries, to a nickel-plated surface. on etched boards in a hot way.To do this, we cover the tracks on the SCF board, apply the flux with a brush.

Conditionally neutral fluxes includeneutralsolder fat, photo is shown above. But it is still recommended to wash it off the board after soldering. Sold in the same jars andactive soldering fat :

Many people like to use fluxLTI-120, which also needs to be washed off, because when used on boards with digital devices, unstable operation is sometimes observed.

Soldering acid is used to solder the cases of devices made of tin and other similar materials. Soldering acid is also a flux, very active, much stronger than SCF, but you cannot solder radio components with it! If the radio components on the board are soldered with acid, the soldering will look strong and reliable, but the place on the board where the acid got into will certainly corrode over time. Moreover, the acid has a high electrical conductivity. Photo of a bottle with acid:

There are special fluxes for brazing steel and even aluminum. They belong to highly active fluxes, and they also cannot be used for soldering radio components. In general, it is better to solder radio components, only with neutral fluxes, the same SCF. One of the fluxes for brazing stainless steel and aluminum is shown in the photo below:

In Soviet times, when many fluxes were in short supply, acetylsalicylic acid tablets or, in other words, aspirin were used as an active flux for soldering. In this case, the output or the part to which the flux had to be applied was laid on the tablet and heated with a soldering iron. At the same time, the smell was, according to the stories of those using, to put it mildly, not pleasant, moreover, harmful to health.

Food citric acid is also a strong active flux. Many used it in order to tin the damaged non-burning tip of a soldering iron. Such a sting is durable in use, if it is not overheated too much.

But if a soldering station or a soldering iron with a regulator is left turned on for a long time at a tip temperature of 480 degrees (maximum), the tip loses its properties and the solder stops sticking to it.In this case, using citric acid as a flux, we can tin the damaged soldering iron tip. After tinning, rinse the sting thoroughly. In general, after which are not based on rosin, it is necessary to rinse the board after soldering. There are specialno-clean fluxes for soldering SMD parts.

For brazing steel and cast iron, they also use a flux calledBura.

For use in conjunction with Borax flux, special medium-temperature solders are required. Also, for soldering with this flux, a powerful soldering iron in the form of an ax or similar is required. Author - AKV.

And so you decided to plunge into electronics with your head, stocked up with a soldering iron, bought solder and ... What next? If the worst is poor, then everyone represents how to solder, but the subtleties of the technology are not known to many and come with experience. Well, I'll speed up this disastrous process and tell you a couple of tricks.

So, about and you probably already read, so we will dance from him. In addition to a soldering iron, you will need solder and flux. More about them.

Solder.
This is a special alloy that melts at a temperature of about 200 degrees. The most common is 60/40 Alloy, also known as POS-61. An alloy in which 60% tin and 40% lead. Its melting point is 183-230 degrees. Usually sold as wire wound on spools.
For small installation, it is better to take the one where the wire diameter is smaller - it is easier to dose. I have two coils, one with 0.3mm solder wire, the other 0.6mm. Well, there is still one and a half millimeter, but I hardly use it. Only if I massively solder massive parts where a lot of solder is needed.
It is better to buy imported solder, unfortunately the Russian product often sucks. Maybe there is a high-quality one, but usually I came across a low-grade slag. A solder coil, as in the picture, should cost from 150-200 rubles, more expensive, cheaper not desirable. It is better to spend money once, but then have a beautiful and high-quality soldering and not take a steam bath. And the coil usually lasts for a year and a half or two, this is the minimum.
It is also useful to buy yourself some Rose alloy. This is also a kind of solder, but its melting point is quite ridiculous - somewhere in the region of 90-100 degrees. This alloy is sometimes useful for dismantling, but this will be a separate article later.

Fluxes
In the process of soldering, from heating, the parts are oxidized and the solder stops wetting them. To prevent this from happening, fluxes are used - substances that dissolve the oxide film, promote soldering. By the way, if someone is not in the know, the process of covering one metal with another is called tinning. I say banal things? Well, after all, the educational program is so educational! :)

Rosin

The simplest and most popular flux. This is a common refined pine resin. When soldering, they first take a little solder on the tip, then poke it into the rosin to pick up the resin on the tip, and then quickly, until the resin has evaporated, braze. The method is not very convenient, so they often do it differently. They take ordinary ethyl (medical) alcohol and dissolve the crushed rosin in it while it dissolves. After that, this solution is applied with a brush to the parts to be soldered and soldered. The activity of rosin is not high, so sometimes nothing works out - the parts do not get tinned, but rosin has one huge advantage, which sometimes covers all its shortcomings. Rosin is completely passive. That is, it does not need to be removed from the place of soldering, since it does not oxidize or reduce metals, while being an excellent dielectric. That is why I try to make the most important rations with alcohol-rosin flux.

One of my favorite fluxes. It is a red liquid, contains rosin and a number of additives. To solder with them, just like with ordinary alcohol-rosin flux - smear on the parts with a brush and solder. But there is one trick. In the initial version, it is a liquid infection, smeared with a thin layer and dries instantly, in general it is not very convenient to use it. I figured out how to overcome this.
I made myself a palette of fluxes - I pasted a bunch of bottle caps on a small group, poured various fluxes into them and pasted this case on a reel of solder. It turned out very conveniently and compactly. So, after pouring it into the lid, I let it stand for a couple of days. During this time, it will dry out and thicken to the state of liquid honey. Now it is already convenient to spread it with a sharp toothpick exactly where you need it. And if it thickens beyond measure, then either add a little bit of alcohol to the drip, or add a little more fresh flux and stir it. The manufacturer claims that there is no need to rinse. In principle, it seems to be the case, he is not active. But something confuses me with the additives that are in it, so I always wash it off. It is washed off with a wide brush dipped in alcohol. Or just a brush under running water from the tap. There is nothing wrong with washing the finished board with water, the main thing is to dry it well afterwards.

Rosin gel
Great stuff. Not so long ago he appeared in radio stores and has already earned my love and respect. It is a thick brown rosin-based paste sold in syringes. Perfectly spreads directly where necessary, does not leave carbon deposits on the soldering iron, like LTI-120. Easily washed off with water or alcohol, in general, rulez!

A lethal active flux that is easily washed off with water, does not leave dirty sticky traces and oxides. But it must be washed off. Rinse off thoroughly. Otherwise, in a couple of years, it can corrode the tracks of the board or its remnants will become conductive and terrible leaks will appear on the surface of the board between the tracks, which will have an extremely negative effect on the operation of the circuit. I'm also not sure about the safety of its vapors. You can use it for a couple of times, but it doesn't smile at me all the time. But in general, this is an awesome flux, they are a pleasure to solder.

Glycerin-Salicylic Flux.
He is FSGL. To be honest, I have no idea where this crap comes from. I have a can of this flux since childhood (in fact, that's why I practically never soldered rosin) - my father stole from a defense enterprise. I have never seen it on free sale. It solders as vigorously as Glycerin-hydrazine, but does not contain impurities that are dubious from the point of view of toxicity. There is 90% glycerin, 5% salicylic acid, 5% water. Buy chtol in a salicylka pharmacy and make it yourself? Painfully crazy recipe. One drawback is that it needs to be washed off, it is active. But it washes off lightly with water.

F-34A
A hellish acid mixture. When soldered, it has an eerie caustic exhaust, with which I poisoned half of our laboratory. You can solder with this muck only in a gas mask and with a powerful hood, but this shit solders everything, something that other fluxes never dreamed of even in a nightmare. This slurry tinns inlet - rust, oxides, steel, spraying, even aluminum can be soldered. So if you need to solder to a rusty nail, then drop this bullshit, hold your breath and LUDI!

Imported no-clean fluxes.
To be honest, I did not use them. They say they are cool, but IMHO it is not rational to solder them just like that - they are too expensive, and they do not sell in our city either, but order me a bag. Rather, they are for professional use, such as repairing cellular or soldering BGA cases (this is when the legs are in the form of an array of balls under the microcircuit case). If you are interested, then look for information on the forums of cell repairmen, they know everything about this business.

Hemp based Dutch flux
I have no idea who makes it and where it is sold, but I know for sure that it is! I was especially convinced of this after poking around in the product diagrams of the company where I used to work. The developers are clearly soldering them. Since I have not yet seen such stoned circuit solutions.

Soldering iron in hand and go !!!
I told you about the fluxes, now, in fact, about the soldering process.
This is not a tricky business. For a start, it is advisable to irradiate the details. You moisten them with flux, hook them with a soldering iron tip with a little bit of solder and smear them on the surface. There is no need to rush, the details should be covered with an even thin shiny layer. There is no need to tinker the conclusions of microcircuits and radio components - they are already tinned at the factory.

The solder should be liquid like water. If it is lumpy, with pronounced graininess and matte, then there are two reasons - wrong soldering iron temperature or solder low grade shit... If the soldering iron is too cold, then the solder will be on the verge of a solid and liquid state, it will be viscous and will not wet. If the soldering iron is overheated, then the solder will instantly become covered with a gray oxide film and will also tinker disgustingly. The ideal temperature of the soldering iron when soldering with POS-40 ( 60/40 Alloy), in my opinion, this is the order 240-300 degrees. Have ST-96 it is enough to set the regulator 2/3 upwards.

If you are soldering a printed circuit board, then the tracks also need to be tinned. But this must be done carefully. Textolite that is sold in the vastness of the Motherland often also turns out to be a rare shit and when heated, the foil falls off from it at a moment. Therefore, it is impossible to warm the board for a long time - the tracks will fall off. Usually I just grease all the tracks well with the flux and run it quickly over each flat soldering iron tip with a drop of solder. As a result, I have perfectly tinned tracks, with an almost mirrored surface.

There is a popular method for quickly tinning large boards:

A braid is taken to remove the solder, this is such a copper washcloth, sold in skeins of 30 rubles a meter. If you don’t find it, then you can pick out the shielding braid from the thick TV coaxial cable - the same bullshit, just more fuss. The board is properly lubricated with flux, the braid is properly impregnated with solder and also watered with flux. Then this crap is tied with a soldering iron on the surface of the board. To prevent the fibers of the braid from sticking to the tracks, it is better to take a larger and more massive soldering iron.

I have improved the way in general.
I took an old powerful 60W soldering iron, wrapped the tip with this braid, impregnated it with Rose's alloy and now a puddle of the board in one motion. Why Rose? And it's easier for them to tinker, the soldering iron when it touches the board cools down sharply, tk. gives off warmth. If the braid is moistened with ordinary solder, then it is immediately welded to the board with separate villi, and the Rose alloy is easy-melting and does not stick.

Soldering transistors, diodes and microcircuits.
Here I would like to draw your attention especially. The point is that semiconductors from too high temperature are destroyed, so there is a risk of overheating the microcircuit. To prevent this from happening, it is advisable to expose a soldering iron 230 degrees or so... This is a perfectly tolerable temperature that the microcircuit can withstand for a long time. You can solder and take your time. For ordinary, unregulated soldering irons, the tip temperature is about 350-400 degrees, so you need to solder quickly, with one touch. No longer than a second on each leg and take at least a 10-15 second break before soldering the other leg. You can also hold the leg with metal tweezers - it will serve as a heat sink.

Soldering wires
It is better to tin the ends separately before soldering, and if the wire is soldered to the printed circuit board, then it is very desirable to drill a hole in the board, start it on the other side, and only then solder. In this case, the risk of tearing off the droshky when jerking by the wire is reduced to zero.

Soldering with solder wire.
This is how microcircuits are usually soldered. They grab it diagonally by the extreme legs, grease everything with flux, and then, holding a soldering iron with one hand and a thin wire of solder with the other, quickly solder all the legs.

Soldering wires in varnish insulation
Any winding wire, such as those that wound a transformer, is covered with a thin layer of varnish. To solder to it, this layer of varnish must be peeled off. How to do it? If the wire is thick, then you can burn it a little with the fire of a lighter, the varnish will burn out, and the carbon can be cleaned off with coarse cardboard. If the wire is thin, then either gently scrape it with a scalpel, holding the scalpel strictly perpendicular to the wire, or take an aspirin tablet and press and poke it with a hot soldering iron tip along the wire on the aspirin. When heated, a substance will be released from aspirin that will gobble up the varnish insulation and clean the wire. True, it will stink strongly :)

Third hand

I recommend getting such a grip. A damn convenient thing, it allows you to hold some Cthulhu when soldering, the ends do not dangle from side to side. By the way, beware of spring loaded conductors! When soldering, he can jump off and throw a drop of solder in your face, how many times this has come to my face and I don’t remember, but it could have been in the eye! So follow the Safety Precautions!

Sponge
The tip of the soldering iron is gradually fouled and covered with carbon deposits. This is normal, usually the flux is to blame, the same LTI-120 burns, God forbid. A special sponge can be used to clean the soldering iron. This yellow garbage is included with the soldering iron stands. It must be moistened with water and squeezed out, leaving it damp. By the way, the sponge constantly dries out so that it does not get wet every time it can be soaked in ordinary medical glycerin. Then it won't dry out at all! Conveniently damn it! If there is no sponge, then take a cotton rag, put it in an iron tray and also soak in water or glycerin. Our installers kept an ordinary waffle towel on the table and wiped a soldering iron on it.

By the way, about safety precautions.

• First, arrange everything so that it is convenient.
• Watch out for power cords. The soldering iron is very likes to burn out his own wire... Straight mania with him. And this is fraught, at best, with wire repair, at worst with a short circuit and fire.
• Do not leave the soldering iron on, even for a short time. The rule " Gone - turned off"Must be carried out by rail.
• Rule two - the soldering iron must be either in hand or on its secure stand... And not otherwise! In no case should you put it on the table or on the first thing that comes along on the table. The cord will drag him away in a moment.
• Don't forget about exhaust and ventilation... If you are soldering, then at least open the window, ventilate the room, and it is better to put a fan (at least 80mm from the computer) or an exhaust hood on the table.

Better to see once than read a hundred times:
No problem! At your service are a bunch of videos from You Tube on request "solder"... You will see how the professionals do it. Watch and Learn!

Soldering is the process of joining radioelements together, and this requires the use of various filler materials such as solder and flux.

Solder is a metal or an alloy of various metals with a melting point lower than that of the metals being joined. It provides a strong connection and fills the gaps between the joining parts of the workpiece.

Flux requirements

Various fluxes are used to improve the soldering of parts and the quality of the resulting joint, as well as to clean the surface from oxide film and grease contaminants. Any flux used in work must meet the following requirements:

1. The melting point must be lower than the melting point of the solder. This is the main condition for a high-quality connection of parts.
2. Should not react with solder.
3. Must ensure good spreading of the solder over the surface and wet all workpieces.
4. Must remove and destroy all oxide and grease films.
5. Residues should be well washed off surfaces.

It is customary to divide fluxes into active and neutral, depending on the presence of acids in their composition. Acidic acids actively interact with many soluble oxide films and fats.

However, they release toxic substances when they evaporate and can damage the circuit board over time if not removed. This is due to the fact that the active acid, which is part of these fluxes, dissolves various metals well, for example, those that make up radio components and the board itself.

Neutral options are often devoid of these drawbacks, but the soldering is not as good as when using acid ones.

Flux groups

All existing drugs can be divided into three groups according to their effectiveness in accordance with GOST:

Overview of various soldering fluxes

The above materials are the most accessible and popular. In addition to them, there are special fluxes in the form of gels, but they have a very high cost and are unlikely to be required in an amateur radio model.

How to replace soldering flux

In the absence of flux and the impossibility of purchasing it, you can use some improvised materials, but it should be remembered that the quality of the soldering will be very low, and the remains of the material are often difficult to remove or toxic. Nevertheless, you should be aware of some adequate options.

It should be remembered that the soldering will be of high quality when the flux is selected correctly. There are perfect fluxes for every metal, and others may not work. In addition, it is highly discouraged to solder boards with active fluxes, especially those containing acids, since with incomplete removal of flux residues from the surface printed circuit board active components will destroy the conductive copper tracks.

The parts should be soldered with a soldering iron with a perfectly tinned tip, and when carbon deposits appear, try to clean the tip in oxide, this will allow very good soldering. Upon completion of the work, the remains of the flux from the surface of the soldered parts and boards must be removed in a suitable way. The board tracks can be coated with special varnishes, for example, zapon varnish, this will protect them from moisture.