The best soldering flux. Likbez on soldering. Flux diluted with acid

Soldering is the process of connecting radio elements 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 that has a melting point lower than that of the metals being joined. It provides a strong connection and fills the gaps between the connected 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 the oxide film and fatty contaminants. Any flux used in the work must meet the following requirements:

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

Fluxes are usually divided into active and neutral, depending on the presence of acids in their composition. Acidic actively interact with many soluble oxide films and fats.

However, they release toxic fumes when they evaporate and can damage the PCB over time if they are 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 the radio components and the board itself.

Neutral options are often devoid of these shortcomings, but soldering is not as good as with acid ones.

Flux groups

All existing drugs can be divided by efficiency into three groups according to 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 are very expensive and are unlikely to be required in amateur radio.

How to replace flux for soldering

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

It should be remembered that 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 soot appears, try to clean the tip in oxidal, this will allow for very good soldering. Upon completion of work, flux residues from the surface of soldered parts and boards must be removed in a suitable way. The tracks of the board can be coated with special varnishes, for example, zaponlak, this will protect them from moisture.

Today, on the shelves of radio markets and electronics stores, you can find a huge number of soldering fluxes of various purposes and prices.

Flux manufacturers offer products really High Quality, but it is quite difficult to find it on the market. The number and variants of fakes are simply amazing in their diversity. Even if you are lucky and you find an original product, its cost will differ significantly from the cost of a fake. Most potential buyers after comparing prices decide to save money and look for a cheaper flux. Masters, on the other hand, select the optimal set of soldering chemicals according to their requirements, which suits them in terms of technical parameters and price. But for this they have to go through unknown fluxes and, through experiments, select the most suitable option for a particular job.

Almost every corner sells hundreds of cheap fluxes with high performance on the label. But inside the package you may expect a very unpleasant surprise.
And now let's figure it out how fluxes are bred and how this affects their technical characteristics.

Rosin instead of flux

Imagine the situation: you bought a superflux, open a tube, and instead of a high-quality flux, there is low-quality rosin (waste after rosin production). Moreover, the same rosin is also very diluted with some kind of contaminated technical petroleum jelly.

Soldering or tinning with such a mixture is simply impossible. The so-called "flux" begins to "run away" from the place of soldering. As a result, we get undeserved conclusions, poor-quality "cold" soldering, and contact pads and tracks instantly fall off the board due to overheating.

Flux diluted with acid

Very often, acids (citric, orthophosphoric) or chlorides (zinc chloride) are added to an already low-quality flux. Compared to rosin, the picture immediately changes - everything is tinned and soldered. It seems that the flux is just super, but electronic boards cannot be soldered with such a flux. It is very difficult and sometimes almost impossible to remove acid residues, especially from under SMD elements. Acid can even remain inside the solder, in the pores of the solder.

As a result, after a month or two, soldering with acid (or zinc chloride) crumbles into powder along with the conclusions of the radioelement. Repair then will be very, very laborious, and sometimes it is completely impossible.

Flux diluted with glycerine

It also happens that glycerin is generously poured into the flux. Glycerin flux solders great, it's cheap and plentiful, but try covering the board with it. And then measure the resistance of the PCB board. That's bad luck: it conducts current from a few to tens of ohms where it should not. Even if you try to wash off the glycerin, and it is washed off easily, the “conductivity” of the board will still remain! Glycerin is absorbed into the textolite (resistance of textolite not covered with copper is 10 to 50 ohm). For most devices, this is simply unacceptable. Even the most simple and banal schemes will be “buggy”. To somehow make the device work, try scratching the textolite between the tracks with a needle.

Conclusion: glycerin, acids, chlorides in non-cleaning fluxes for working with radio electronics, BGA and SMD components should not be used.

Basic requirements for a high-quality flux for working with lead elements, BGA and SMD:

• no corrosivity
• good lubricating properties
• high wetting ability
• no boiling when heated to operating temperature
• lack of electrical conductivity
• ease of removal of residues if necessary
• support for lead-free and lead-containing solders
• no-clean soldering technology (remains can not be washed off)
• ease of application (gel, paste)
• affordable price.

Now let's see what they offer us on the market.

Fluxes meet all of the above requirements trademark CHIPSOLDER FLUX.

The fluxes of the series are also of sufficient quality. SP (SP-10+, SP-15+, SP-18+, SP20+, SP30+).

They do not contain acids, chlorides or glycerin. SP fluxes are available in different consistency: paste, gel, liquid (L-NC-3200, L-NC-3600). They do not conduct electricity, and it is not necessary to wash off the residue.

These fluxes comply with all declared standards and have been tested when soldering lead parts, conductors, BGA and SMD elements, as well as sensitive solar panels.

Flux characteristics and their features

Let's now look at some of them in more detail.
First, let's deal with the name. What do all those big letters stand for?

• G(gel) - gel-like flux.
• NC(no clean) - does not require rinsing.
• 5268 - flux index.
• LF(lead free) - suitable for lead-free solders.

CHIPSOLDER G-NC-5268-LF

This flux is suitable for soldering tinned contacts. It has good thermal conductivity, the contact pad remains on the board, and not on the soldering iron tip. Flux gel CHIPSOLDER G-NC-5268 LF is a high quality, translucent, synthetic no-clean flux with resinous characteristics. Used for soldering and desoldering BGA/SMD components. Suitable for working with a soldering iron, hot air gun, IR station, as well as for reballing.

The flux is made from highly purified components. Conveniently fixes BGA and SMD components when soldering ("landing"). Fully supports both conventional and lead-free soldering technology. Halogen-free for long-term reliability and excellent soldering characteristics.

It has a minimal, "soft" activity during soldering, which allows you to not wash off residues. It does not boil, does not leave a dark "soot", after soldering it remains a transparent gel. It loses transparency only at a temperature of -5 ° C, but at the same time retains its properties. Easily removed with any universal alcohol-based (alcohol-petrol) based cleaner and a paper towel.

It has excellent thermal conductivity (the component heats up as evenly as possible), it is very convenient to use. Solvent free, does not dry out outdoors and does not harden after soldering. Suitable for multiple use.

CHIPSOLDER-G-NC-6500-LF

These fluxes are similar in performance to the CHIPSOLDER flux series, but are slightly less expensive. It should be noted that the cost did not affect the quality. They can also work great and get good results. And now let's dwell on each of them in more detail.

SP-10+

This is a cheap and pretty good low-active flux. It is recommended to use for mounting and dismounting FLIP CHIP, BGA and SMD components, crystals, as well as for repair work using a soldering iron, hot air gun, IR equipment.

Has almost zero activity. Used for soldering and desoldering tinned leads. Suitable for lead-free solders. SP-10+ is absolutely safe for radio components. Evenly distributes soldering temperature and prevents peeling of printed conductors. It has a sticky consistency (viscous, sticky), does not cause corrosion, securely fixes the elements during soldering. It also does not conduct electricity.

The flux is used without subsequent washing in printed circuit assemblies. Suitable for working in various environmental conditions.

SP-15+

The main difference is in the consistency.
SP-30 It is a translucent, sticky gel. Flux is intended for repair and production of electronics. Can be used with all standard solders.

So, let's sum up.

All fluxes are formulated for high quality soldering. All of the above fluxes are used in various environmental conditions and with different process features.
The main differences between SP fluxes are consistency and potency. Therefore, it is necessary to select the flux based on the scope and convenience during operation.

As for CHIPSOLDER brand fluxes, they are not as versatile as SP fluxes. When choosing a CHIPSOLDER flux, you definitely need to know how to use it and for what purpose.

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

purpose

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

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

Flux types for soldering

Conventionally, fluxes are divided into two main categories - oxidizing and reducing. Also, depending on the need to perform certain tasks, fluxes are isolated for melting metal, 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 (acid);
• 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. Thanks 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 residues quickly corrode the junction of parts.

Acid free fluxes

Acid-free soldering flux, commonly known as rosin, is a substance prepared 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 surface.

The main advantage of the flux in the form of rosin is the absence of the effect of separation of the surfaces to be joined during soldering. This flux is actively used for soldering copper, bronze, brass.

Activated fluxes

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

Anti-corrosion fluxes

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

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

Protective fluxes

Since there is no destructive chemical effect on metals during application, 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 primarily includes petroleum jelly, wax, powdered sugar, olive oil, and other substances with low chemical activity.

Storage

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

Flux paste for soldering also needs to be stored in a closed container. The optimal conditions for such a flux is a room with a low level. Although 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 flame, since most fluxes in this category are highly flammable. In this case, the storage temperature should not be lower than 10 and not more than 25 degrees Celsius.

Flux application

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

Probably, it is not necessary to talk once again about the properties and advantages of using fluxes when soldering. Just 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 will be frankly of poor quality, since the solder will be too unreliably fixed on the surface to be soldered.

How to prepare flux for soldering with your own hands?

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

As a self-made flux that is suitable for tinning steel and copper surfaces, you can use acetylsalicylic acid dissolved in a small amount of water, acetone or alcohol. It is convenient to store such a liquid flux in a container from varnish, using a cap 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 a successful job. First of all, you 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 fluxes based on rosin. These fluxes are a modified version of regular rosin by adding a number of ingredients known as activators.

Inactive fluxes have improved antioxidant properties. Due to the pasty or liquid state, such fluxes can be applied directly to circuit boards or soldered metal joints. This flux is ideal for soldering 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, when repairing mobile phones and other modern portable devices. Fluxes are suitable for this, which do not foam or boil during operation, have minimal corrosivity, and are also easily applied to boards.

Often medium active fluxes are used by craftsmen service centers digital repair mobile devices. Usually they are used for soldering the smallest microcircuits. Moreover, they are suitable for use not only with lead, but also with lead-free solders.

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

Finally

Correct selection of suitable Supplies when performing soldering is a guarantee of high-quality work performed. Beyond Choice good flux it is required to choose a solder, a nozzle for a hair dryer, a soldering iron tip, etc., corresponding to the nature of the soldering.

Even using the most advanced soldering stations in your work with the wrong flux, solder or tip, you can end up with a completely different result than you expected. Enough water has flowed since then, when experts actively used classic soldering irons with a power of up to 60 W with a home-made, file-turned copper tip, as well as ordinary rosin as a flux. At present, the use of such a material and technical base is extremely inefficient.

Today, on the shelves of radio markets and electronics stores, you can find a huge number of soldering fluxes of various purposes and prices.

Flux manufacturers offer really high quality products, but it is quite difficult to find them on the market. The number and variants of fakes are simply amazing in their diversity. Even if you are lucky and you find an original product, its cost will differ significantly from the cost of a fake. Most potential buyers after comparing prices decide to save money and look for a cheaper flux. Masters, on the other hand, select the optimal set of soldering chemicals according to their requirements, which suits them in terms of technical parameters and price. But for this they have to go through unknown fluxes and, through experiments, select the most suitable option for a particular job.

Almost every corner sells hundreds of cheap fluxes with high performance on the label. But inside the package you may expect a very unpleasant surprise.
And now let's figure it out how fluxes are bred and how this affects their technical characteristics.

Rosin instead of flux

Imagine the situation: you bought a superflux, open a tube, and instead of a high-quality flux, there is low-quality rosin (waste after rosin production). Moreover, the same rosin is also very diluted with some kind of contaminated technical petroleum jelly.

Soldering or tinning with such a mixture is simply impossible. The so-called "flux" begins to "run away" from the place of soldering. As a result, we get undeserved conclusions, poor-quality "cold" soldering, and contact pads and tracks instantly fall off the board due to overheating.

Flux diluted with acid

Very often, acids (citric, orthophosphoric) or chlorides (zinc chloride) are added to an already low-quality flux. Compared to rosin, the picture immediately changes - everything is tinned and soldered. It seems that the flux is just super, but electronic boards cannot be soldered with such a flux. It is very difficult and sometimes almost impossible to remove acid residues, especially from under SMD elements. Acid can even remain inside the solder, in the pores of the solder.

As a result, after a month or two, soldering with acid (or zinc chloride) crumbles into powder along with the conclusions of the radioelement. Repair then will be very, very laborious, and sometimes it is completely impossible.

Flux diluted with glycerine

It also happens that glycerin is generously poured into the flux. Glycerin flux solders great, it's cheap and plentiful, but try covering the board with it. And then measure the resistance of the PCB board. That's bad luck: it conducts current from a few to tens of ohms where it should not. Even if you try to wash off the glycerin, and it is washed off easily, the “conductivity” of the board will still remain! Glycerin is absorbed into the textolite (resistance of textolite not covered with copper is 10 to 50 ohm). For most devices, this is simply unacceptable. Even the most simple and banal schemes will be “buggy”. To somehow make the device work, try scratching the textolite between the tracks with a needle.

Conclusion: glycerin, acids, chlorides in non-cleaning fluxes for working with radio electronics, BGA and SMD components should not be used.

Basic requirements for a high-quality flux for working with lead elements, BGA and SMD:

• no corrosivity
• good lubricating properties
• high wetting ability
• no boiling when heated to operating temperature
• lack of electrical conductivity
• ease of removal of residues if necessary
• support for lead-free and lead-containing solders
• no-clean soldering technology (remains can not be washed off)
• ease of application (gel, paste)
• affordable price.

Now let's see what they offer us on the market.

All of the above requirements are met by trademarked fluxes CHIPSOLDER FLUX.

The fluxes of the series are also of sufficient quality. SP (SP-10+, SP-15+, SP-18+, SP20+, SP30+).

They do not contain acids, chlorides or glycerin. SP fluxes are available in different consistency: paste, gel, liquid (L-NC-3200, L-NC-3600). They do not conduct electricity, and it is not necessary to wash off the residue.

These fluxes comply with all declared standards and have been tested when soldering lead parts, conductors, BGA and SMD elements, as well as sensitive solar panels.

Flux characteristics and their features

Let's now look at some of them in more detail.
First, let's deal with the name. What do all those big letters stand for?

• G(gel) - gel-like flux.
• NC(no clean) - does not require rinsing.
• 5268 - flux index.
• LF(lead free) - suitable for lead-free solders.

CHIPSOLDER G-NC-5268-LF

This flux is suitable for soldering tinned contacts. It has good thermal conductivity, the contact pad remains on the board, and not on the soldering iron tip. Flux gel CHIPSOLDER G-NC-5268 LF is a high quality, translucent, synthetic no-clean flux with resinous characteristics. Used for soldering and desoldering BGA/SMD components. Suitable for working with a soldering iron, hot air gun, IR station, as well as for reballing.

The flux is made from highly purified components. Conveniently fixes BGA and SMD components when soldering ("landing"). Fully supports both conventional and lead-free soldering technology. Halogen-free for long-term reliability and excellent soldering characteristics.

It has a minimal, "soft" activity during soldering, which allows you to not wash off residues. It does not boil, does not leave a dark "soot", after soldering it remains a transparent gel. It loses transparency only at a temperature of -5 ° C, but at the same time retains its properties. Easily removed with any universal alcohol-based (alcohol-petrol) based cleaner and a paper towel.

It has excellent thermal conductivity (the component heats up as evenly as possible), it is very convenient to use. Solvent-free, does not dry out in the open air and does not harden after soldering. Suitable for multiple use.

CHIPSOLDER-G-NC-6500-LF

These fluxes are similar in performance to the CHIPSOLDER flux series, but are slightly less expensive. It should be noted that the cost did not affect the quality. They can also work great and get good results. And now let's dwell on each of them in more detail.

SP-10+

This is a cheap and pretty good low-active flux. Recommended for mounting and dismounting FLIP CHIP, BGA and SMD components, crystals, as well as for repair work using a soldering iron, hot air gun, IR equipment.

Has almost zero activity. Used for soldering and desoldering tinned leads. Suitable for lead-free solders. SP-10+ is absolutely safe for radio components. Evenly distributes soldering temperature and prevents peeling of printed conductors. It has a sticky consistency (viscous, sticky), does not cause corrosion, securely fixes the elements during soldering. It also does not conduct electricity.

The flux is used without subsequent washing in printed circuit assemblies. Suitable for working in various environmental conditions.

SP-15+

The main difference is in the consistency.
SP-30 It is a translucent, sticky gel. Flux is intended for repair and production of electronics. Can be used with all standard solders.

So, let's sum up.

All fluxes are formulated for high quality soldering. All of the above fluxes are used in various environmental conditions and with different process features.
The main differences between SP fluxes are consistency and potency. Therefore, it is necessary to select the flux based on the scope and convenience during operation.

As for CHIPSOLDER brand fluxes, they are not as versatile as SP fluxes. When choosing a CHIPSOLDER flux, you definitely need to know how to use it and for what purpose.

Flux provides stable combustion, contributes to the formation of a reliable welded joint, removes unnecessary impurities from the welding zone and generally improves the quality of work. you can buy in the store, modern manufacturers offer a large assortment. But we suggest you make the flux yourself. It won't take long, but it will save you money.

Primarily, soldering flux used for welding and small parts. There is also a special flux for bga soldering. In this article, we will share the "recipe" for making various kinds flux or, more simply, solder, which can be used in most small soldering jobs.

Before proceeding with the manufacture of flux, you need to understand its varieties and features. To connect two parts, it is necessary to maintain a certain temperature in the welding zone, depending on the metal, it can vary greatly. In this case, the melting point of the solder should be noticeably higher than the melting point of the metal with which you are working. This is where the choice comes from. You need to consider the materials that you connect to each other, their melting point and strength.

Generally speaking, fluxes are hard and soft. Hard fluxes have a high melting point, while soft fluxes have a low melting point. They are also called refractory and fusible. If the part to be welded is thin, use a soft flux. If it is larger in diameter and requires a long warm-up, then use hard refractory solder.

A refractory flux (or solder) melts at a very high temperature (from 400 degrees Celsius) and ensures the formation of a strong one. But when using such a flux, parts often overheat and may not work. This problem is especially relevant for radio engineers and anyone who is fond of electronics.

The fusible flux melts at low temperatures and allows it to be used when working with boards and circuits, for example. Such a flux consists of lead to a greater extent and tin to a lesser extent. May additionally contain impurities of other metals. There are separate fusible fluxes that melt at temperatures up to 150 degrees. They are used when working with transistors.

A high-quality flux should conduct heat freely, ensure the strength of the welded joint, stretch well, protect against corrosion and be resistant to the melting temperature of the metal.

Regardless of the type of flux that you use, the soldering area after work must be wiped with a cloth previously moistened with acetone. The seam itself can be cleaned with a small stiff brush pre-moistened with solvent.

Soldering itself as a method of joining metals has a number of advantages. With it, you can achieve a durable and tight, resistant to corrosion and oxidation. Also, soldering does not require special skills, this work can be done by a person with minimal theoretical knowledge.

Flux Making Instructions

So how do you make your own soldering flux? It all depends on the destination. If you need to solder thin ones, then you can use rods with a diameter of 1 mm. We will make them ourselves.

We will need a small bottle or any other vessel with a flat bottom. In the bottom we make a hole with the diameter that we need (in this case, 1-2 mm). We take lead or tin and melt it with a gas burner. Pour into our bottle. Molten metal will begin to flow out of the hole, you need to prepare the surface in advance. You can use a sheet of tin, for example. The resulting "rods" must harden, then they need to be cut. Experienced craftsmen use special molds to make bars. See also a review of flux for bga soldering.

We need rosin crystals, which need to be crushed into powder. Wrap the crystals in a heavy cloth and tap them with a mallet (preferably a woodworking mallet or kitchen meat mallet). In a ratio of one to one, mix the powder and alcohol. Alcohol can be purchased at a pharmacy. It is advisable to mix in a glass container, such as a small jar. Thoroughly stir the alcohol with the powder and put the jar in hot water. Once again, mix everything thoroughly until a homogeneous consistency. Ready! The resulting flux can be used with a medical syringe or poured into an empty nail polish bottle.