Flux for soldering, of course, you can do yourself. For this, collected in the forest with coniferous trees the resin must be melted in a tin over low heat, stirring occasionally, and then simply poured into containers. When the mixture hardens, it will turn into rosin. But let's not engage in amateur performances, it's not worth it, but rather consider different types of fluxes that can be purchased at any electronic store.
Requirements for fluxes used in soldering work
- The melting point of the flux must be less than the melting point of the solder.
- The flux must be completely molten and flow well during the soldering process.
- Should quickly and completely dissolve the oxides of the soldered metal.
- Must not form chemical bonds with metal or solder.
- It should evenly cover the surface of the metal at the place of soldering, preventing its oxidation during the soldering process.
- Should not evaporate quickly during soldering, and its decay products should be displaced by solder and easily washed off after soldering without causing corrosion of the soldering point
Gel fluxes are, in principle, ordinary rosin, but in a gel state. They are best used for delicate soldering of radio components and repairs mobile phones, laptops, smartphones, etc. Their main feature is that they are very easy to wash off with Flux-Plus, acetone or gasoline, alcohol can also be used.
Currently, two types of gel fluxes can be found on sale: Flux-Plus and its cheap Chinese counterpart RMA-223
Flux-Plus is considered the best among gel products. Even a full one will be able to solder with him. But its price of 20 green pieces of paper is not at all encouraging. So before you take it, think about it, is it worth the money? If you are a repairer of smartphones or tablets, then it will definitely pay off for you, and for simple lovers of soldering, I would advise its Chinese counterpart.
RMA-223 Soldering Gel Flux is a Chinese counterfeit of the proprietary Flux-Plus. The cheapest one can be ordered from Chinese internet stores. When soldering, it also spreads well and envelops the solder. I advise everyone to use it and you will not regret it.
For cooking at home and with our own hands, we need the following ingredients, medical or technical alcohol for dissolving rosin, a hammer or something similar for grinding rosin, a container for storing the resulting liquid composition. Then we crush the pieces of rosin with a hammer, I advise you to wrap them in a bandage or any piece of cloth before that. Pour the resulting powder into a vial and fill it with alcohol (I’ll immediately answer your question “Vodka will not work”), after a few days of settling, the product will serve perfectly for soldering operations.
Why can't you solder with rosin? It is possible, but not very convenient, since it is necessary to quickly bring the evaporating rosin to the place and it will still have to be smeared a little with a soldering iron on all soldered surfaces.
It is used in soldering work as a liquid agent for oxidized copper, ferrous metal and stainless steel. Can also be used to remove rust. After use, a protective film forms on the treated surface, which prevents the corrosion process.
Used for brazing carbon and low alloy steels, nickel and alloys. The liquid is active at a temperature of 290-350 °C. After using a special agent, the surfaces must be washed with a solution of soda ash
Manufactured on a vaseline base, suitable for soldering highly oxidized metals from ferrous and non-ferrous metals
The active agent is used in radio editing electronic components and printed circuit boards. Rinse with water or alcohol after use
This liquid can be purchased at a regular pharmacy, it costs much less than alcohol, and the effect is the same, although it contains 90% ethyl alcohol.
Clean-free. If desired, excess liquid can be wiped off with a rag. In addition to soldering aluminum, it can be used for soldering stainless steels, nickel, copper and other metals.
In terms of its properties and characteristics, rosin fully meets the requirements for fluxes, it just needs to be able to solder.
The specific gravity and melting point of rosin are lower than those of solder
It melts completely and has good fluidity at the correct soldering temperature. At the same time, there is a small plus compared to standard fluxes, namely, molten rosin does not “leak out” from the soldering point
Rosin completely dissolves oxides, and this reaction proceeds at a temperature that is several degrees lower than the melting temperature of the solder
Rosin is always neutral, it does not react and does not form chemical compounds with solder and base metal.
It evenly covers the surface of the soldered metal, creating protection against oxidation.
Rosin does not burn out at the soldering temperature, while the solder completely expels all its decomposition products
After the soldering process, the rosin residue left on the PCB is easily washed out
It is a transparent glassy resin, light yellow in color, hard but brittle. It is obtained from the resin of various coniferous trees. Rosin is essentially a mixture of resin acids (their chemical formula is C 20 H 30 O 2), various types of fatty acids and a small amount of oxidized and neutral substances. The basis for high-quality rosin is abietic acid.
Rosin dissolves perfectly in alcohol, ether, turpentine, worse - in kerosene, gasoline. It is completely insoluble in ordinary water.
According to the method of obtaining rosin, it happens:gum- obtained from the resin of coniferous trees. Mostly pines. This type of rosin has practically no fatty acids in its composition.
extraction- obtained by extracting with gasoline the crushed wood of coniferous trees. This type of rosin is darker, with a lower softening point and a fairly high content of fatty acids.
tall rosin is a by-product of cellulose sulphate production in the manufacture of soap.
Rosin soldering technique
Soldering with rosin is easy enough. Before soldering, parts must be tinned. To do this, a soldering iron heated to operating temperature with a clean tip is lowered into rosin.
Then you need to cover with solder and apply it to the surface to be soldered. After that, the parts are fixed and in the place of their contact they are briefly touched with a sting. The solder spreading over the surface with a thin film after cooling will create good connection. After soldering, the remains of rosin are washed off with alcohol or a solvent.
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 work, 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 a 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 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 masters of service centers for the repair of digital 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
The correct selection of suitable consumables when performing soldering is a guarantee of a quality work performed. In addition to choosing a good flux, you need to choose a solder, a nozzle for a hair dryer, a soldering iron tip, and other things that correspond to the nature of 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.
All the best! This rating contains the best fluxes for soldering and is compiled from personal preferences and feedback from electronics repairmen. Many readers will now think - “Well, finally! Master Soldering has started to write something about soldering!” and they will be right - for almost 4 years, not a single decent article about the soldering process has been written on the blog, although the name of the blog seems to oblige. I admit, I confess, I will correct the situation.
I plan to publish reviews of soldering processes, soldering tools, soldering videos and new technologies in the soldering world. And today I will give my rating of the 10 best fluxes for soldering. This rating is based on personal preferences and all kinds of feedback from familiar electronics repairmen of various levels and does not claim to be exclusive. Let's go - fluxes for soldering.
Rating of the most popular soldering fluxes
What should we know about flux?
The flux is designed to improve the quality of the process of soldering two metal surfaces by soldering and, when heated, cleans the surfaces from oxide and greasy films. A good flux should have a low melting point and low specific gravity. Before the solder melts, it must have time to dissolve the oxides and not penetrate deep into the solder joint during the soldering process. The flux should spread well and wet the surface of the solder and the metal at the place of soldering.
In fifth place is the most popular flux of all time, the muse of musicians, gift of nature, her majesty rosin. Rosin is gum (from the resin of coniferous trees, has almost no fatty acids), extraction (extraction of coniferous sawdust with gasoline, contains more fatty acids than gum) and tall (residues after sulfate-cellulose production of soap).
In fourth place is the beloved alcohol-rosin flux SKF or FKSp (soldering alcohol-rosin flux). It consists of 60-80% alcohol and 20-40% rosin. Such a mixture can be prepared at home with your own hands. For example, many simply crumble rosin into alcohol in a ratio of about 1 to 3. It is convenient to use in a syringe with a needle. But when stored in a loosely closed syringe, it begins to dry out on the needle and stops flowing.
Advantages:
affordable and popular inactive flux, easy to apply, does not smoke much.
Flaws:
when heated, the alcohol begins to rapidly evaporate and hiss.
What to solder: copper wires, gold-plated and silver-plated contacts of microcircuits and radioelements, brass, zinc.
How to rinse: alcohol, solvents, gasoline, alcohol-gasoline mixture.
So we got to the Top 3 best soldering fluxes. On the prizes, I placed professional fluxes, which in ordinary life may not be useful. But in the craft - they are very necessary.
Fluxes Amtech RMA-223 and Kingbo RMA-218
The third bronze place is occupied by Amtech RMA-223 - it is a gel flux - a mixture of crushed rosin and solvent.
I also suspect that there may be activators and fragrance in the composition. - most main feature forgeries- on the sticker there is an inscription in small print “Coliformia” instead of “California”, however, oddly enough, the Chinese fake flux is very good in operation, and many services just sit on it. Although the masters from mysku do not advise to take this flux for Ali, but it is better to take an analogue.
Advantages:
it is convenient to apply the gel, good solderability, you can not wash it, a fake is cheap (about 200 rubles), but it soldered very well with it and smelled of perfume.
Expensive (a 10 g tube can cost 1,500 rubles), smelly, fakes come across. The price is a limiting factor, for example, a 30 g tube can cost from 2,000 rubles.
What to solder: mainly responsible lead-free and lead soldering.
How to rinse: most can not be washed off, alcohol, solvent, there is a proprietary solvent T2005M.
This concludes the Top 10 best soldering fluxes. Of course, there are a lot of other fluxes, including good Chinese and top German and Japanese ones. But I haven't used them, so I can't adequately describe them.
If you, dear readers, use any other flux and consider it the best in the world, then be sure to write to me about it in the comments. Perhaps it will appear in the rating after testing.
Soldering Master tried for you.
It is well known that fluxes are used to remove solder residues and contaminants, as well as to protect against oxidation.
A variety of chemical compositions are used as fluxes: rosin, orthophosphoric acid, soldering acid and active soldering fat, Borax, TAGS glycerin flux, etc. Today we will talk about another type of flux - gel fluxes.
Gel fluxes are the same rosin, only in gel form. They are used for primary and resoldering of critical components, at the household level when repairing laptops or smartphones. Their important advantage is that they are easily washed off or do not require washing at all.
On the forums, you can often read that the best flux gel is FluxPlus, but there is also its Chinese counterpart RMA-223. This is a big mistake! Of course, there is a Chinese analogue, but RMA-223 is a high-quality flux made in America by Amtech.
What to do with Chinese fakes? After all, the market is large, there is demand, there is counterfeit. Of course, you can deal with the numbers that should be indicated on the label, lot numbers, etc. for a long time. Or you can just buy fluxes from trusted suppliers. For example, our Amtech fluxes are only purchased from official representative Amtech in Russia.
Amtech's two most popular flux brands today are RMA-223 and LF-4300.
LF-4300 It is a medium viscosity, water washable flux that does not require cleaning and is used with both lead and lead free alloys. It is convenient to use for installing solder balls, BGA components and reballing. This flux gel is widely used in the installation of all types of Flip Chip and CSP.
The flux is water-washable, but in most cases residues can be left on the boards. If the boards are going to be washed, then it can be removed with deionized water at a temperature of 40-60 degrees.
RMA-223- This is a rosin flux, it is recommended for lead-free soldering only. It has excellent spreadability and wettability. Just like the LF-4300, it is used to work with components in BGA/PGA packages. The flux has a weak activity, so its residues must be washed off.
Both flux gels are labeled with -TF at the end. This means Tacky Paste Fluxes, i.e. sticky, viscous fluxes. They are often compared to honey because they should have the gooey consistency of honey and the same yellow-amber color. Just their stickiness and ductility provide the convenience of working with solder balls when soldering BGA.
Amtech gel fluxes are supplied in a syringe, which allows you to precisely dose the flux and apply it only to those areas where it is needed without contaminating adjacent surfaces.
Progress does not stand still, and gel fluxes have entered the market for about a dozen years. What is their feature and why are they needed at all?
What is gel flux
Gel fluxes are the same rosin, but in a gel state. I do not know the technology for the production of gel fluxes, but I know for sure that these fluxes are used for delicate soldering of radio components, as well as for repairing mobile phones, laptops and other small electronics. Their big plus is that they are easily washed off (you may not even wash off) with Flux-Off, acetone or Galosha gasoline. You can read more about cleaning chemistry in the article Chemistry for an electronics engineer.
So, now about everything in order ...
Flux Flux-Plus
Flux Plus considered the best gel flux.
It is a pleasure to solder with him, unless, of course, it is a fake. Repairers of mobile phones, laptops and other small electronics love it very much, as it does not leave carbon deposits, interacts well with solder, and also has a pleasant, though not healthy, smell. The only downside is its price. At the time of this writing, its cost ranges from 1000 rubles. Therefore, for a beginner there, the flux will hit your pocket very hard.
Flux RMA-223
RMA-223- cheap Chinese analogue the famous flux Flux-Plus. RMA (R osin M ild A ctivated) - “slightly activated rosin”. A group of resinous fluxes with various combinations of activators: organic acids and their compounds.
There is also RMA-223 and American origin. The price of an American one is slightly lower than Flux-Plus, but also not cheap, somewhere around 500 rubles.
The Chinese RMA-223 flux is several times cheaper than Flux-Plus, but performs the same functions, in no way inferior to the famous Flux-Plus. I found the cheapest one for 35 (!) rubles apiece, if you buy in bulk on Aliexpress. In principle, the quality is satisfied. In order not to miscalculate with the choice of flux, there is one rule, the more yellow it is, the better it is.
To make it more convenient to dose, I poured it into a syringe.
Since RMA223 flux is viscous, a simple thin needle will not work here. Therefore, it will be necessary to purchase needles separately. Choose a diameter slightly larger than a standard needle. Needle length - according to your preferences.
Choose to your taste and color!
Gel fluxes and health
Gel fluxes, especially Chinese RMA-223, are highly toxic and smoke heavily. Not suitable for soldering BGA chips. It’s good for soldering various small things, BUT think about it ... How much is your health worth? More precisely, how much will his treatment cost you after 5-10 years of such work. Not only does it smoke very strongly, it is not an easy task to wipe it off after soldering without residue!
What can be done in this case? Make a good hood and ventilate more often workplace. Try not to inhale gel flux fumes. Compared with pine rosin, our pine rosin is almost harmless ;-)
What will give us a high-quality flux?
1. Confidence in soldering quality.
2. Will not turn us into asthmatics. Reduces the chance of dying from lung cancer, etc.
3. Significantly save time and nerves in our hard work.
The miser ends up paying an order of magnitude more ...
Conclusion
One syringe of RMA flux is enough for me for about a year with moderate use. When soldering, such a flux spreads very well and wets the solder. Soldering is obtained as factory ;-), you can’t tell the difference. As I said, it is indispensable for soldering and even chips in phones, laptops and other small things, but it can also be used with great success when soldering your electronic trinkets. Try it and you will be surprised by the cleanliness and accuracy of soldering ;-)
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