Of course, you can make your own flux for soldering. For this purpose, 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, you will get rosin. But let’s not engage in amateur activities, it’s not worth it, but rather consider different types of fluxes that can be purchased at any radio-electronic store.
Requirements for fluxes used in soldering work
- The melting temperature of the flux must be lower than the melting temperature of the solder.
- The flux must be completely molten and have good fluidity during the soldering process.
- It should quickly and completely dissolve the oxides of the metal being soldered.
- Should not form chemical compounds with metal or solder.
- It should evenly cover the surface of the metal at the soldering site, preventing it from oxidizing during the soldering process.
- It should not quickly evaporate during soldering, and its decomposition products should be displaced by solder and easily washed off after soldering without causing corrosion of the soldering area
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; you can also use alcohol.
Currently, two types of gel fluxes can be found on sale: Flux-Plus and its cheap Chinese analogue RMA-223
Flux-Plus is considered the best among gel products. Even a full person can solder with it. But its price of 20 green pieces of paper is not at all encouraging. So before you buy, think about whether it is worth the money? If you are a repairer of smartphones or tablets, then it will definitely pay for itself, but for ordinary fans of soldering, I would recommend its Chinese counterpart.
Gel soldering flux RMA-223 is a Chinese counterfeit of the branded Flux-Plus. The cheapest place to order it is from Chinese internet stores During soldering work, it also spreads well and envelops the solder. I advise everyone to use it and you won’t go wrong.
To prepare it at home and with our own hands, we will need the following ingredients: medical or industrial alcohol to dissolve the rosin, a hammer or something similar to grind the rosin, and 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 doing this. Pour the resulting powder into a bottle and fill it with alcohol (I’ll answer your question right away: “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 you need to very quickly bring the evaporating rosin to the place and you will also have to spread it a little with a soldering iron on all soldered surfaces.
It is used for 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 is formed on the treated surface, which prevents the corrosion process.
Used for soldering carbon and low-alloy steels, nickel and alloys. The liquid is active at a temperature of 290-350 °C. After using a special product, the surfaces must be washed with a solution of soda ash
Made on a Vaseline base, suitable for soldering highly oxidized metals from ferrous and non-ferrous metals
The active agent is used in radio installation electronic components and printed circuit boards. After use, rinse with water or alcohol is necessary.
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.
No laundering. If desired, wipe off excess liquid with a rag. In addition to soldering, aluminum can be used for soldering stainless steels, nickel, copper and other metals.
Rosin, in its properties and characteristics, fully satisfies 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 advantage compared to standard fluxes, namely, the molten rosin does not “leak out” from the soldering site
Rosin completely dissolves oxides, and this reaction occurs at a temperature that is several degrees lower than the melting temperature of solder
Rosin is always neutral, it does not react and does not form chemical compounds with solder and the base metal.
It evenly covers the surface of the soldered metal, creating protection against oxidation.
Rosin does not burn out at soldering temperature, while the solder completely expels all its decomposition products
After the soldering process, any remaining rosin remaining on the printed circuit board can be easily washed off
It is a clear glassy resin, light yellow in color, hard but brittle. It is obtained from the resin of trees of various coniferous species. Rosin is essentially a mixture consisting of resin acids (their chemical formula is C 20 H 30 O 2), various types of fatty acids and small amounts of oxidized and neutral substances. The basis for high-quality rosin is abietic acid.
Rosin dissolves well in alcohol, ether, turpentine, and worse - in kerosene and gasoline. Completely insoluble in ordinary water.
According to the method of obtaining rosin, there are:gum– obtained from the resin of coniferous trees. Mostly pine trees. This type of rosin has virtually no fatty acids in its composition.
extraction– obtained by extracting crushed coniferous wood with gasoline. This type of rosin is darker, has a lower softening point and has a fairly high fatty acid content.
tallow rosin- It is a by-product of cellulose sulfate production in the manufacture of soap.
Rosin soldering technique
Soldering with rosin is quite easy. Before starting soldering, it is necessary to tin the parts. To do this, a soldering iron heated to operating temperature with a clean tip is dipped into rosin.
Then you need to coat it with solder and apply it to the surface to be soldered. After which the parts are fixed and at the point of contact they are briefly touched with a sting. Solder spreading over the surface as a thin film after cooling will create good connection. After soldering is completed, the remaining rosin is washed off with alcohol or solvent.
Soldering flux is an auxiliary substance, the use of which helps clean the surfaces of metal elements being 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 begin joining parts using a soldering iron, you need to select 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, promotes the spreadability of solder and, accordingly, improves the quality of soldering.
A good flux for soldering can only be selected based on the nature of the metal joints and the alloy of the solder. Residues of any fluxes, regardless of their type, must be removed from the joints after completing the work, since they themselves contaminate the metal and can lead to the development of corrosion processes.
Types of fluxes for soldering
Conventionally, fluxes are divided into two main categories - oxidizing and reducing. Also, depending on the need to perform certain tasks, fluxes are used 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 (acidic);
- acid-free;
- anti-corrosion;
- activated;
- protective.
Active fluxes
This 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, 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 joint of parts.
Acid-free fluxes
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 o C, the use of such a flux makes it possible to dissolve the oxides of lead, copper, and tin, reliably cleaning the metal surfaces.
The main advantage of flux in the form of rosin is the absence of the effect of separation of the joined surfaces during soldering. This flux is widely used for soldering copper, bronze, and 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 suitable for soldering a wide range of metals and alloys, such as iron, copper, steel, nickel, zinc, silver, as well as copper parts without the need for pre-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 soldering flux 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 upon completion of soldering by wiping the parts with acetone or alcohol.
Protective fluxes
Since there is no destructive chemical effect on metals during use, protective flux can be used for soldering microcircuits. Like most 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 weak chemical activity.
Storage
The most common alcohol-based fluxes usually have a liquid consistency. Therefore, they need to be stored in a carefully sealed, airtight 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. The optimal conditions for such flux are a room with a low level. Although the paste does not absorb moisture from environment, there is a danger of moisture condensation on the walls of the container and surfaces located nearby.
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 be no lower than 10 and no more than 25 degrees Celsius.
Application of flux
When soldering, the joints are thoroughly cleaned, coated with flux and heated with a soldering iron. At the point of application, the flux begins to foam and smoke. At this moment, a small amount of solder must be applied to the tip of the soldering iron, which will subsequently cover the surfaces to be connected.
It’s probably not worth talking about the properties and advantages of using fluxes for soldering once again. You just need to take a soldering iron and try to connect the parts without flux. In this case, the soldering process will be truly lengthy, and the result will be frankly of poor quality, since the solder will be too unreliably fixed to the surface being soldered.
How to prepare flux for soldering yourself?
The simplest option for making your own flux is to use a rosin-alcohol base. To begin with, rosin powder is poured into the container, after which it is filled 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-prepared flux, which 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 liquid flux in a varnish container, 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 an almost 100% guarantee of successful completion of the job. Here you should first of all focus on the material of the parts being connected, 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. Such fluxes are a modified version of ordinary rosin as a result of the addition of a number of components known as activators.
Inactive fluxes have improved antioxidant properties. Due to their paste or liquid state, such fluxes can be applied directly to circuit boards or soldering joints of 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. Suitable for this purpose are fluxes that do not foam or boil during operation, have minimal corrosion, and are also easy to apply to boards.
Often, medium-active fluxes are used by service center technicians for the repair of digital mobile devices. They are usually 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 fluxes. They can be used for almost any type of soldering. 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 quality work done. In addition to choosing a good flux, you need to select a solder appropriate to the nature of the soldering, a nozzle for a hair dryer, a soldering iron tip, etc.
Even if you use the most advanced soldering stations in your work, if you have the wrong flux, solder or tip, you can end up getting a completely different result than you expected. Enough water has flown under the bridge since then, when specialists actively used classic soldering irons with a power of up to 60 W with a homemade copper tip turned by a file, as well as ordinary rosin as a flux. Currently, the use of such material and technical base is extremely ineffective.
All the best! This rating contains the best fluxes for soldering and is compiled from personal preferences and reviews of electronics repair specialists. Many readers will now think: “Well, finally! Master Soldering has started to write at least something about soldering!” and they will be right - for almost 4 years not a single decent article has been written on the blog about the soldering process, although the name of the blog seems to oblige. I admit, I repent, I will correct the situation.
I plan to publish reviews of soldering processes, soldering tools, soldering videos and new technologies in the world of soldering. And today I will give my rating of the 10 best fluxes for soldering. This rating was compiled based on personal preferences and all sorts of reviews from familiar electronics repairmen of various levels and does not pretend to be exclusive. Let's go - soldering fluxes.
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 with solder and, when heated, cleans the surfaces of 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 metal at the soldering site.
In fifth place is the most popular gumboil of all time, the muse of musicians, gift of nature, Her Majesty rosin. Rosin can be gum (from the resin of coniferous trees, has almost no fatty acids), extraction (extraction of pine sawdust with gasoline, contains more fatty acids than gum) and tall (residues after sulfatocellulose soap production).
In fourth place is the beloved alcohol-rosin flux SKF or FKSp (alcohol-rosin soldering flux). It consists of 60-80% alcohol and 20-40% rosin. This mixture can be prepared at home with your own hands. For example, many people 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, the needle begins to dry out and stops flowing.
Advantages:
An affordable and popular inactive flux, easy to apply, does not smoke much.
Flaws:
When heated, the alcohol begins to evaporate violently and hiss.
What to solder: copper wires, gold-plated and silver-plated contacts of microcircuits and radio elements, brass, zinc.
What to wash off with: alcohol, solvents, gasoline, alcohol-gasoline mixture.
So we have come to the Top 3 best fluxes for soldering. In the prize places I have placed professional fluxes, which in ordinary life may not be useful. But in crafts 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 there may be activators and fragrance in the composition. – most main feature fakes– on the sticker there is an inscription in small print “Coliformia” instead of “California”, however, strangely enough, the Chinese counterfeit flux is very good in use, and many services rely only on it. Although the masters from mysku do not recommend using this flux, but it is better to take an analogue.
Advantages:
it’s convenient to apply the gel, good solderability, no need to wash it, the fake is cheap (about 200 rubles), but it solders quite well and smells of perfume.
Expensive (a 10 g tube can cost 1,500 rubles), smelly, there are fakes. 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.
What to wash off with: Most do not need to be washed off, alcohol, solvent, there is a branded solvent T2005M.
With this, I consider the Top 10 best fluxes for soldering complete. 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 talk about 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 rankings after testing.
Master Soldering tried his best for you.
It is common knowledge 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 solder 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 re-soldering 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 rinsing at all.
You can often read on forums that the best flux gel is FluxPlus, but there is also its Chinese analogue 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 counterfeits? After all, the market is large, there is demand, and there are counterfeits. Of course, you can spend a long time sorting out the numbers that should be indicated on the labeling, lot numbers, etc. Or you can simply purchase fluxes from trusted suppliers. For example, our Amtech fluxes are only purchased from official representative Amtech in Russia.
Today, the most popular brands of Amtech fluxes are two: RMA-223 and LF-4300.
LF-4300 is a water-washable flux of medium viscosity, it does not require cleaning and is used with both lead and lead-free alloys. It is convenient to use for installing solder balls, BGA pins 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 undergo cleaning, it can be removed using deionized water at a temperature of 40-60 degrees.
RMA-223- This is a rosin flux, it is recommended only for lead-free soldering. It has excellent spreadability and wettability. Like the LF-4300, it is used to work with components in BGA/PGA packages. The flux has weak activity, so its remains must be washed off.
Both flux gels are marked at the end with the letters -TF. This stands for Tacky Paste Fluxes, i.e. sticky, viscous fluxes. They are often compared to honey because they are supposed to have the viscous consistency of honey and the same yellow-amber color. It is their stickiness and ductility that make it easy to work with solder balls during BGA soldering.
Amtech gel fluxes are supplied in a syringe, which allows you to accurately 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 been on the market for about a dozen years now. What is their feature and what are they for?
What is gel flux
Gel fluxes are the same rosin, but in a gel state. I don’t know the technology for producing 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 advantage is that they are easily washed off (you don’t even need to wash them off) with Flux-Off, acetone or Galosh gasoline. You can read more about cleaning chemistry in the article Chemistry for electronics engineers.
So, now first things first...
Flux-Plus flux
Flux-Plus considered the best gel flux.
Soldering with it is a pleasure, 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 residue, interacts well with solder, and also has a pleasant, although not healthy, smell. The only negative is its price. At the time of writing, its cost ranges from 1000 rubles. Therefore, for a beginner, flux will hit your pocket very hard.
Flux RMA-223
RMA-223- cheap Chinese analogue the famous Flux-Plus flux. RMA (R osin M ild A ctivated) – “slightly activated rosin.” A group of resin-containing fluxes with various combinations of activators: organic acids and their compounds.
There is also RMA-223 and American origin. The price of the American one is slightly lower than Flux-Plus, but also not cheap, somewhere around 500 rubles.
Chinese flux RMA-223 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 it in bulk on Aliexpress. In principle, I am satisfied with the quality. In order not to make a mistake when choosing a flux, there is one rule: The yellower it is, the better the quality.
To make dosing more convenient, I poured it into a syringe.
Since RMA223 flux is viscous, a simple thin needle will not work here. Therefore, you will need to purchase needles separately. Choose a diameter slightly larger than a standard needle. The length of the needle is according to your preference.
Choose to your taste and color!
Gel fluxes and health
Gel fluxes, especially Chinese RMA-223, are very 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 expensive his treatment will cost you after 5-10 years of such work. Not only does it smoke a lot, but cleaning it off after soldering without any residue is not an easy task!
What can be done in this case? Make a good hood and ventilate more often workplace. Try not to inhale fumes from gel fluxes. Compared to pine rosin, our pine rosin is almost harmless;-)
What will high-quality flux give us?
1. Confidence in the quality of soldering.
2. Will not turn us into asthmatics. Will reduce the chance of dying from lung cancer, etc.
3. It will significantly save time and nerves in our difficult work.
The stingy one ends up paying an order of magnitude more...
Conclusion
One syringe of RMA flux lasts me about a year with moderate use. When soldering, this flux spreads very well and wets the solder. The soldering turns out just like factory soldering;-), you can’t tell the difference. As I already said, it is indispensable for soldering even microcircuits 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 at how clean and neat the soldering is;-)
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