What is soldering acid for - Metals and their processing

Why do you need acid when soldering - Metalworker's Handbook

Every person who has had to work with radio electronics has repeatedly used a soldering iron to solve their problems, so he knows what the operating principle of such equipment is. But due to the unpleasant odor emitted when processing a structure using classic solder, as well as significant difficulties at different stages of operation, this technology is not in great demand and has a number of simpler analogues.

To make the upcoming soldering more productive, many welders use special substances - fluxes, with the help of which the solder spreads evenly over the soldering site. Among the main fluxes, rosin and soldering acid are distinguished. The first option is indispensable when soldering copper and silver, and acid is used in particularly difficult cases. How soldering acid works, the composition and other features of such a substance are the main questions that concern many inexperienced beginners.

If we highlight the main recommendations for successful soldering with acid, they will look like this:

When choosing a suitable solution, you need to understand the type of metal or alloy. When soldering iron, including galvanized iron, a unique type of soldering acid is used, represented by a solution of zinc chlorate. Soldering of stainless steel is carried out using phosphoric acid for soldering, as well as multi-component fluxes. A material such as aluminum cannot be soldered , which is due to the lack of suitable fluxes capable of dissolving the oxide film of the material. Acid cannot be used for soldering printed circuit boards, as this increases the risk of the formation of corrosive elements and short circuits between conductors.
If you intend to use soldering acid for your own purposes, you can purchase it in the form of a paste at the appropriate store. Nevertheless, many welders make their own soldering acid, claiming that such an action does not require any special difficulties. You need to take about 100 ml of hydrochloric acid, put pieces of zinc in it, for example, removed from batteries, and wait for the chemical reaction to complete, during which hydrogen will be released. Given this feature, it is better to conduct the event in a ventilated environment away from sources of fire. If the hydrogen bubbles stop rising, let the solution sit until clear, and then carefully pour it into the bottle. That's it, the highly effective soldering acid is ready.

Instructions for use

Immediately before soldering, it is necessary to clean the surface with a file or sandpaper, which will avoid all kinds of contamination.
Acid should be applied to the adhesion site, for which you can use a brush.
Next, you need to cover the structure to be soldered with solder based on tin or its alloy. If the substance does not apply evenly, you will have to repeat the acid treatment again.
At the next stage solder carefully surfaces.

When working with a heated soldering iron, do not forget about safety rules and try not to clutter the work area with materials that ignite very quickly.
After completing the procedure the acid must be neutralized, using an alkali, such as a soda solution, and then rinse the joint to get rid of any remaining acid.
In rare cases, acetylsalicylic acid plays the role of a flux, although its use requires a more complex approach.

Features of metal soldering

If you have ever worked with a soldering iron, then you know that soldering is a unique type of permanent connection of metal products using low-melting metal. The technology itself is selected taking into account the type of metals that are to be soldered, as well as the environmental conditions where the action will be performed. For example, processing printed circuit boards from some electronics and repairing silver jewelry are significantly different from each other.

When soldering this way, you should use a soldering iron, solder, and also a flux, which is colophonium.

The step-by-step instructions look like this:

It is no secret that for soldering elements with a high silver content, solder is used, which contains about 60% tin and 40% lead, which can melt at a temperature of 180 degrees Celsius. Try to prepare solder, which will be indispensable for soldering electronic circuits. This product consists of thin tubes that are filled with resin and act as a flux.
The surface that will be solderable must first be cleaned of any defects and irregularities that may appear when exposed to the oxide film. In this case, the heated solder can create an effective connection with the silver.
The part in the soldering zone is heated to such temperatures that natural melting of the solder begins. However, at this stage, some difficulties cannot be avoided, which may be associated with insufficient power reserve of the soldering iron for sufficiently high-quality heating. When soldering silver products, it is important to protect the area from possible exposure to atmospheric oxygen. In this case, colophonium is used, which can create a protective film over the soldering area.
As for soldering jewelry, it is carried out using high-temperature solders that correspond to the metal standard, or using solders of a lower standard, but containing silver. Soldering jewelry with tin is necessary only in the most extreme cases, and only after prior agreement on all details with the owner of the ring, chain, bracelet or other item. If you do not know how to perform such an action correctly, this can cause damage to an expensive structure.

Boards

It's no secret that soldering radio components into boards is a simple process . It is much easier to do than connecting loose wires, since the holes in the boards are intended to fix the soldered parts.

However, you need to understand that the final result is directly related to the experience and responsibility of the worker. The first circuit that is assembled on a breadboard cannot be called very successful.

But don’t worry - after some time the quality of the connections will increase significantly.

Step-by-step instructions and features of such soldering consist of the following points:

The main goal of the upcoming work is to effectively connect the chip to the board so that a uniformly good soldering is obtained. The event can be divided into several separate stages.
First, you need to simultaneously bring the solder and the tip of an already heated tool to the area where the connection is required. It is important to follow the key rule, making sure that the soldering iron tip is in full contact with the pin being processed and the board itself.
During processing, you cannot change the position of the soldering iron tip until the entire contact area is covered with an even layer of solder. In most cases, this takes from 0.5 to 1 second. This time period ensures sufficient heating of the soldering area.
At the next stage, you need to circle the tip of the tool near the contact being processed in a semicircle, moving the solder in the opposite direction. In the same way, apply another millimeter of solder to the soldering area. During this period, the selected area will warm up quite well, so the solder melted under the influence of surface tension will be distributed evenly over the contact area.
After successfully applying the required amount of solder to the selected location, you can move the wire away from the soldered area.
And at the last stage, you should quickly remove the tip to the side. In a short period of time, the liquid substance, with a small layer of flux, will take its final shape and harden, creating a strong connection.

It is important to understand that if the sting is sufficiently warmed up, the action will not take more than 1 second. Try to hone your skills and follow the recommendations of professionals. This way you can achieve incredible success.

Copper

Every man can learn to solder, because this procedure does not require any special skills or secrets. In any case, the ability to solder can be very useful and useful in everyday life, where you need to connect wires and parts of electrical circuits, repair a car radiator, and also install copper pipeline elements.

It's no secret that copper is one of those materials that lends itself very well to soldering.

In addition, the surface of products made of this metal can be easily cleaned from oxide film, dirt, unevenness and other defects without the use of expensive chemicals and aggressive agents.

Most fusible metals have excellent adhesion to copper and do not require the use of expensive or complex fluxes. Copper practically does not interact with air when heated.

Due to such unique properties , metal can be soldered in a wide variety of environmental conditions, using various types of fluxes and solders.

To solder parts, you should use electric soldering irons or soldering stations with different power. It is known that the greater the mass and volume of the part, the higher the power indicators of the working tool should be. If you've never soldered before, a 25-50W device might be your best bet

Other soldering features

At the learning stage, many beginners have a question: “what is solder and flux.” Solder is a common form of low-melting metal that is required for successful soldering of radio circuits, electronic components, and jewelry.

Most often, solder is made from tin, but in its pure form such metal is not cheap, so it is used only for tin-plating and soldering of utensils, which are used for storing and preparing food.

If it is necessary to solder wires and electrical circuits, the tin-lead solder option is used.

When performing soldering work, you may need the following tools and accessories:

stand for soldering device;
side cutters;
pliers;
tweezers;
stationery knife;
vice;
desoldering pump or copper braid.

The soldering process itself includes several steps:

Cleaning the selected area to a shine.
Dipping the soldering iron tip into rosin for more effective cleaning.
Firmly pressing the connected elements together.
Then it requires applying a soldering iron with a small amount of solder at the end to the junction of such parts.
Next, you need to run the soldering iron tip along the part or wire, doing this as quickly as possible to avoid burning out the rosin on the tip.
The soldering area should be thoroughly heated so that the rosin, when melted, covers the entire surface of the part, and the solder fills the gap between the parts.
Be sure to remove excess solder with a soldering iron or desoldering iron. It also wouldn't hurt to use braid.

If all operations are carried out exactly according to the established rules, the hardness of the solder will become maximum, and its distribution will be uniform.

If during the solder solidification stage the soldered parts move from place, most likely the soldering is not good enough. To avoid such a course of events, it is enough to learn how to avoid making many mistakes.

Conclusion

Considering the above information, we can confidently say that if you wish and have the appropriate guidance, you can comprehend all the secrets of soldering in a few hours and experiments. The main thing is not to give up when faced with mistakes and troubles.

At home, you can learn to solder in a variety of ways, which will allow you to achieve the highest quality fastening of parts and the tightness of containers.

Today, using soldering acid, you can successfully join almost all types of metals and alloys, electrical wires, car radiator housings, metal utensils and many other everyday items.

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Composition of soldering acid and purpose

Soldering work requires the mandatory use of high-quality flux, which ensures reliable soldering of the material and solder, as well as high electrical conductivity and long service life. Soldering acid is often used as a flux. There are several types of such chemical compounds. The composition of soldering acid directly affects its area of application.

Types of acid fluxes and their composition

Specialists use several types of soldering acids for soldering. They are distinguished by composition and application properties:

Based on orthophosphoric acid, it is an inorganic compound with the formula H3PO4. As a result of the use of this acid, a protective shell is formed on the surface of the processed material, which prevents further corrosion processes. As a rule, the substance is transparent. Very rarely, the solution may have a cloudy tint - this does not indicate a low-quality product. The color depends on the amount of impurities.
Based on sulfuric acid as a flux. The formula has been known since school days - H2SO4. Appearance is characterized by the solution being slightly viscous, odorless and colorless. The substance is very potent, so before use it is diluted with either SO3 or H2O anhydride. The percentage of acid in the flux can range from 25 to 80%.
Based on hydrochloric acid - its composition is expressed by the formula HCL. It has a peculiar smell and may have a yellow tint. It is a very strong acid, so for soldering processes it is diluted with water. In order to improve the solderability of materials, zinc is often added to the acid.

Thanks to the aggressive action of acid, oxide deposits and rust residues are removed from the surface of the material.

Pros and cons of soldering acid

The solution has a number of undoubted positive properties:

eliminates almost all oxides formed on metal structures;
prevents the re-formation of oxidative plaque;
used in a dissolved substance, but can also be used in concentrated form;
simple technology of use, characterized by a quick effect on the metal.

Of course, there are also disadvantages:

Not all materials can be soldered with acid, since the substance is very aggressive;
the acid retains its properties for no more than six months, and during this time it is necessary to follow storage rules;
store in special containers in rooms with excellent air circulation - direct contact with the substance without protective equipment is very dangerous for the human body.

Soldering acid is widely used when soldering miniature small objects, as it is available in liquid form.

Purpose of acid

Before soldering, any part must be prepared for applying solder. In addition to removing foreign particles (sand, debris, dust), you need to clean the surface of the material from the oxidizing film. It is with the help of soldering acid that you can chemically act on the surface of the material, get rid of existing plaque and effectively protect the metal from re-formation of the film.

Basically, soldering acid is used for the following metals:

nickel;
copper;
iron;
non-ferrous metals.

For soldering brass or copper products, for example, borax is used. But to solder steel or aluminum objects, you only need soldering acid. At the end of the process, the flux must be washed off with an aqueous solution with the addition of alkali.

Correct choice of fluxes

The choice of acid depends on the application. Not only the composition of the substance is taken into account, but also its concentration. Although under certain conditions, it can be diluted at home. Chemicals have a short shelf life, so when purchasing, you need to pay attention to the date of manufacture of the flux.

When choosing an acid, you need to study the properties of each of them. If the products are quite old and corrosion processes are pronounced, the use of phosphoric acid is optimal. It will effectively remove oxides and rust, which will ensure a reliable connection.

Sulfuric acid, due to its aggressiveness, is used for soldering products of large thickness, since the harm from it in this case is minimized.

Hydrochloric acid, on the contrary, is universal in its application. It is used for soldering various metals, including non-ferrous metals and their alloys.

It is important to note! If a noticeable amount of sediment is observed in the solution, the acid is unsuitable for use. Either the expiration date has expired or the product is of poor quality.

Features of application

Experts note that covering the main surface of the material with acid is sufficient and immersing the soldering iron in an additional chemical solution does not make any sense. Solder will easily fill all areas treated with soldering acid.

Attention! Soldering acid cannot be used for soldering thin products and microcircuits.

The main distinctive property of acids can be identified as having a negative effect on the human body.

Mandatory conditions for working with chemicals are through ventilation, working in special clothing and applying the solution only with a brush. The flux quickly fills the surface being treated and after a short time begins to interact with the oxide shell. When the acid comes into contact with areas of the skin, the affected area is disinfected with alkali and washed with water.

Be sure to use special protective equipment and, if possible, protect yourself as much as possible from possible contact with the chemical solution.

Even in a diluted state, vapors of chemical acids can cause irreparable damage to the mucous membranes of organs. Therefore, various actions with acids require care and conscientiousness.

Only after carefully studying the features and properties of chemical fluxes can you begin soldering various materials.

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Soldering phosphoric acid

Experienced electronics engineers and home radio amateurs know that for a high-quality connection you will need not only a soldering iron, but also additional accessories. For soldering, flux and solder are used, the latter is made on the basis of lead and tin, often offered in the form of wire. The characteristics of the ratio of wire and flux may differ in parameters depending on the type of product.

The second component is flux; a common form is used in the form of rosin. It helps to quickly and efficiently solder copper parts, wires and other materials. Soldering acid can be used to work with materials such as brass, nickel, stainless steel, etc.

Soldering acid

Features of application and soldering with soldering acid

The category into which soldering acid falls differs from other reagents and has a number of positive properties. As a flux, the product is distributed only in liquid form; some compositions can be diluted to reduce the concentration when interacting with metal. Before using the element, it is worth understanding what soldering acid is needed for.

Before soldering metals, it is necessary to prepare the areas for use. With prolonged use, metals tend to oxidize, and a layer of dirt and dust forms on them. If it is possible to deal with dirt mechanically, using sandpaper or a file, then oxides can only be removed using chemical solutions. Soldering acid helps prevent the formation of a new film and remove existing deposits.

Cleaning metal with soldering acid

Basic metals that can be treated with soldering acid:

copper alloys of any proportions;
iron products;
nickel;
all kinds of non-ferrous metal alloys;
steel.

Brass and copper alloys can be soldered using borax. Aluminum or steel products will not be connected in any way without soldering acid. Before soldering with acid, the part is treated to remove solid deposits, and after soldering it is washed off with water with a low alkaline content. Varieties of soldering products are produced according to GOST 23178-78 standards, they have fluidity and low viscosity.

Types of soldering acids and application features

Soldering acid is divided into two main types, regardless of the scope of application, orthophosphoric and hydrochloric type. Regardless of the composition, the purpose is to remove oxides and contaminants from soldering areas. A high-quality, neat seam can only be made if the metal preparation conditions are met. The durability of materials is increased due to the formation of a protective film against oxidation on the joint surface.

It is important to know that using flux when working with electronic boards is strictly prohibited. Thin and fragile elements can be erased from the board structure; soldering acid produces conductive connections. All these factors can have a detrimental effect on the performance of the unit and the overall condition of the structure.

Zinc chloride flux

A solution of zinc chloride is used for soldering iron compounds. The composition is zinc dissolved in hydrochloric acid. The solution is made as follows:

granular zinc is prepared;
depending on the technical specifications, add a solution or concentrate;
After the chemical reaction of zinc, it is possible to use a mixture.

Zinc chloride

Proportional parts are taken using the example of 1 liter of saline solution per 400 grams of granulated zinc. At the end of the work, the surface should be treated to stop the reaction; a soap solution is excellent for this. Before making it yourself, you should remember that it is important to follow the sequence. The acid is diluted with zinc, and gases are formed, resulting in a rather explosive mixture. All actions are carried out in a ventilated place.

Olein is excellent for soldering aluminum alloys. Not used in its pure form, available only in technical condition. A stable state is achieved by mixing olein with various fatty acids. Next, lithium iodide reacts, which completes the mixing of the aluminum soldering mass.

Soldering with oleic acid allows you to join materials from copper and aluminum alloys, without the formation of a chemical film and oxidation.

Oleic acid B-115

Flux is used to protect against corrosion processes at the joint; under mechanical stress, a new film is formed, which allows you to not worry about the reliability of the connection.

Instead of soldering acid, other fluxes do not have similar properties; it is possible to use machine oil with ground sawdust; the soldering process involves rubbing in the composition during joining. When heated, the oleic type of soldering acid evaporates, but the soldering area is tinned, so there is no point in worrying about the quality of the connection.

Orthophosphoric acid

When treating metals with an orthophosphorus solution, a protective film is built that prevents the formation of oxides and chemical reactions of the metal. The characteristics of the solution consist of a colorless substance, inorganic. The hygroscopic structure in the form of a paste structure reacts when heated and dissolves into a liquid composition. It has good flow properties and is easy to clean with water after use.

Soldering with phosphoric acid

Phosphoric acid is used for soldering carbon and alloy steels. Copper and nickel alloys are also suitable for work; the operating temperature for soldering starts at 350 degrees. The acid film is loosened and removed to the surface by dissolving the oxide layer. Reliable soldering is achieved by forming an oxide film with orthophosphoric acid.

Flux VTS

Salicylic base, common in aspirin, is used as a component of soldering flux. It is most widely used when working with precious metals, due to its weak interaction with the particles of the product.

The main advantage is protection from oxidation of the soldering area; there is no need to remove flux, unless additional requirements are imposed.

VTS flux paste

The versatility of application and low-cost manufacturing allow the use of soldering acid based on salicylic compounds. Caustic emissions require a working hood when performing soldering operations, and the negative side is poor interaction with aluminum.

It is possible to use improvised means, just grind an aspirin tablet or another drug containing salicylic acid. The powder is applied to the soldering area; when working with wires, soldering can be done directly on the tablet. A more convenient mixture is made together with Vaseline, proportions 1 to 2; the paste can be easily applied to the soldering area with a tampon and removed when the work is completed.

Benefits of acid

Each composition has certain advantages, soldering accessories are no exception.

Soldering aluminum with acid

Main positive aspects:

The convenience of the process, soldering allows you to process a contact in a hard-to-reach place due to its fluidity properties.
Increased aggressiveness allows you to destroy oxide films and rust deposits. Typically, oxide films are not visible to the eye, so the connection must be processed.
There is no need to worry about the subsequent formation of an oxide film; soldering acid counteracts this, even mechanical stress.
The variety of metals with which it is possible to perform operations allows the solution to be used for every job.

Flaws

In addition to the positive aspects, there are also some disadvantages that can limit the use of the chemical element:

It is strictly forbidden to use acids when working with radio circuits and small electronics. The properties of some compositions are such that the tracks are destroyed during the processing and growth of new conductive elements.
The shelf life is underestimated due to the volatility of gases, so it will not be possible to purchase these fluxes with a reserve. There are also requirements for storage conditions, non-compliance with which can lead to damage to the material;
The composition is harmful to humans if inhaled or in contact with skin. It is recommended to use personal protective equipment during mass work; soldering should be carried out in a well-ventilated area.

Composition and physicochemical properties

Orthophosphoric acid has the formula H3PO4, which consists of phosphorus itself and diethylamide. The proportions may vary from the required concentration, in most cases a ratio of 1 to 4 is used. There is a type of acid with zinc impurities in ratios of 1 to 2 parts of the solution.

Phosphoric acid formula

The basic properties of the material imply aggressiveness. Active interaction occurs with any material; this fact requires careful handling of compounds. During work, you must adhere to special rules, because...

a positive or negative scenario may occur. The liquid form allows the composition to penetrate into hard-to-reach places and achieve high soldering strength.

The main types of soldering acid are solutions, since a 100% concentration will not allow working with most metals.

Features of choice

The composition of soldering acid is selected in accordance with the working surface of the material. The main criterion should be the quality of the solution, because If the concentration is incorrect, you can always lower it at home. It is not permissible to use formulations with sediment or cloudiness in the container.

It is important to remember that liquid fluxes are one of the few soldering accessories that have an expiration date, which you need to pay attention to before use.

Difficult choices always haunt you when purchasing. The compositions are different, there are a large number of manufacturers on the market. It is necessary to determine what type of work will be performed; for this purpose, the purpose of the soldering acid composition is studied. Orthophosphorus compounds are the most common, they fight oxides well and are not so aggressive. Salt is more versatile, because... applies to a variety of metals. Sulfur is the most active option, used when soldering thick products.

DIY making

With some knowledge and available materials, it is possible to make soldering acid at home. The set of ingredients is not large; they can be purchased at a hardware store:

hydrochloric acid in its pure form;
lump zinc, which is sold by the chemical reagents department; if it is not possible to purchase, a finger-type battery is carefully opened;
container made of glass or ceramic material.

Soldering acid is made by hand in a certain sequence. It is necessary to fill the container with pieces of zinc, then fill it with saline solution. The actions are carried out in a well-ventilated area; if the solution gets on the skin, you must immediately rinse with running water. After production, the mass is poured into an airtight container for proper storage.

Precautionary measures

Aggressive properties require a special approach to safety precautions. Storage is carried out in original packaging, protected from direct sunlight.

It is better to carry out work with good ventilation, using the necessary protective equipment.

The skin reacts negatively to aggressive substances. If it gets on your hands, wash it immediately with water and laundry soap. Inhalation may cause oral irritation, and if it gets into the eyes, seek professional help.

How to use soldering acid when soldering products

Soldering acid (also called etching acid) is used in the preparation or repair of various metal objects or devices, when some parts or small parts need to be connected to each other very firmly.

Not everyone knows what soldering acid is, why it is needed, where you can get it and the principles of working with it.

Necessary procedures before work

Before soldering, as before any other work, it is necessary to perform a number of procedures that contribute to a better result of the work:

Before joining metals to each other, they must be cleaned of dirt and oxide film that prevents the substance (hereinafter referred to as “solder”) from spreading over the surface. This condition must be observed, otherwise the solder, like a ball, will concentrate in one place and will not spread.
For the most successful spreading of solder over the material, it must be treated with a flux solution, which will protect the metal from corrosion and oxidation. The most common flux is rosin. This "household" flux (more often used for household work than for industrial purposes) is used for alloys of the common metals: copper, brass and aluminum. In the case of iron, cast iron and steel, so-called pickling acid is used for soldering.

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DIY soldering acid: composition and purpose, DIY production

If we highlight the main recommendations for successful soldering with acid, they will look like this:

When choosing a suitable solution, you need to understand the type of metal or alloy. When soldering iron, including galvanized iron, a unique type of soldering acid is used, represented by a solution of zinc chlorate. Soldering of stainless steel is carried out using phosphoric acid for soldering, as well as multi-component fluxes. A material such as aluminum cannot be soldered , which is due to the lack of suitable fluxes capable of dissolving the oxide film of the material. Acid cannot be used for soldering printed circuit boards, as this increases the risk of the formation of corrosive elements and short circuits between conductors.
If you intend to use soldering acid for your own purposes, you can purchase it in the form of a paste at the appropriate store. Nevertheless, many welders make their own soldering acid, claiming that such an action does not require any special difficulties. You need to take about 100 ml of hydrochloric acid, put pieces of zinc in it, for example, removed from batteries, and wait for the chemical reaction to complete, during which hydrogen will be released. Given this feature, it is better to conduct the event in a ventilated environment away from sources of fire. If the hydrogen bubbles stop rising, let the solution sit until clear, and then carefully pour it into the bottle. That's it, the highly effective soldering acid is ready.

What is soldering acid and why is it needed?

Almost everyone who learned to solder on their own experienced failures at first. Either the solder did not want to stick to the workpieces and parts, or the soldered seam suddenly fell apart.

Without knowing the technology of soldering work, it is difficult to guess why this happens. And the secret is simple - the parts were not prepared for soldering, and the solder did not “stick” to the surfaces. Soldering acid, which removes oxides and promotes an excellent connection, helps to cope with the problem.

Purpose

To prepare parts for applying solder, it is necessary to clean them of particles of foreign materials - dust, sand, water. In addition, it is necessary to remove the oxide film from the surface, which is present on almost all metals.

And if the first condition is easy to cope with mechanically, using a file, needle file, or sandpaper, then the second condition is difficult to fulfill without the use of chemical compounds - an oxide film very quickly appears on the surface of the metal.

Substances that remove film and prevent the formation of a new one are called fluxes, and the most effective of them is soldering acid. It is an active flux, that is, during soldering it chemically affects the composition of the metal surface.

Professionals never question why soldering acid is needed; they know very well that very often it is impossible to complete the assigned tasks without it.

Soldering acid is used for the following metals:

copper and its alloys;
nickel;
iron;
structural steel;
alloys of non-ferrous metals.

If copper or brass parts are successfully soldered with borax, then it is often possible to solder aluminum or steel workpieces to each other only using soldering acid. Upon completion of work, the active flux must be washed off with water containing a small amount of alkali.

You can buy acid in stores, or make it yourself using chemical reagents. Although purchasing raw materials can be more expensive than ready-to-use flux.

What does it consist of?

In general, soldering acid is called zinc chloride, but the composition of the substances used in practice is somewhat different. Most often, soldering is done using preparations based on hydrochloric or phosphoric acid with the addition of solvents.

Concentrated hydrochloric acid is not applicable because it corrodes the metal. For electronic circuits, acidic substances are not used, soldering using rosin or choosing another inactive flux.

One of the universal types of liquid flux can be considered soldering acid FCA, produced by chemical industry enterprises.

This drug contains:

zinc chlorides;
ammonia (ammonium chloride);
hydrochloric acid;
water purified from impurities.

At home, soldering acid is made by dissolving zinc in hydrochloric acid. To obtain satisfactory results, you need to know how to solder metals and alloys with soldering acid, and also strictly follow safety rules when working.

General rules of application

For soldering, tin-lead solder (PLS) is usually used. Its main component is always tin, and lead is added in proportions, depending on which the solder acquires the properties necessary for soldering.

Lead makes the material softer and more fluid, while tin provides strength to the hardened joint.

Despite the presence of lead, the fluidity is often not enough to overcome the surface tension forces in a drop of solder, and with little adhesion to the metal surface, the solder remains in the form of a drop that does not want to stick to the parts.

If the surfaces are first cleaned of oxides, the adhesion force will exceed the forces of surface tension and the solder will spread over the surface, ensuring good adhesion, that is, sticking.

To clean the surface, it is mechanically cleaned using a file or sandpaper and soldering acid is applied. It can be applied with a small brush made of natural materials or with a small spatula.

Often the composition is contained in plastic bottles with dispensers that are convenient to use. The flux must cover the entire surface to be soldered, otherwise the solder will not stick well to it.

During contact of the heated solder with the surface, the soldering acid evaporates, but its presence is no longer required. After the solder is applied, it itself performs a protective function, preventing oxidation. This process is called tinning.

Both soldered workpieces are subject to tinning. After tinning, you can easily connect them by applying additional solder to the joint.

Of course, when soldering with a soldering iron, the tool must also be clean and the tip, made of copper, must not contain oxide films. To do this, the tip must also be tinned first by dipping it while heated in soldering acid and applying solder to it.

Soldering without a soldering iron

Sometimes when soldering using soldering acid, you can do without a soldering iron. One of these methods is used, for example, when soldering twisted wires during electrical installation work on electrical wiring.

In this case, flux is applied to the twist with a brush, and for a better effect, the twist is dipped in a small container with acid. After this, the twist is immersed in a container with molten solder and held for about 1 minute so that the wires warm up well and the solder penetrates to all points of their surface. This soldering provides excellent electrical conductivity when connecting wires.

After soldering, it is necessary to remove the remaining soldering acid from the joint in order to avoid metal corrosion and destruction of the joint in the future.

It must be remembered that when installing printed circuit boards of electronic circuits, when soldering electronic components of radio devices, it is not recommended to use soldering acid, since very thin conductive traces of the boards can be damaged. When applying flux, soldering acid can dissolve them.

Safety regulations

In the production of soldering acid, hydrochloric and phosphoric acids are used. They are very active (although phosphorus is weaker) and easily react with many chemicals. When such substances come into contact with the skin, they cause a chemical burn.

Even when diluted, their vapors can damage the mucous membrane of the sensory organs.

Taking into account the above facts, safety rules when handling soldering acid include secure storage of the drug, the use of protective clothing and gloves, and good ventilation of the work area.

Source: https://svaring.com/soldering/flus/pajalnaja-kislota

❌Why can’t you solder parts with acid? Why is acid dangerous?

Category: Soldering 09/05/2019 · : 0 · Reading time: 4 min · Views:

Soldering acid is a highly active flux. Reacts with metal, even after soldering. Corrodes oxides, oxide films and perfectly tins difficult areas.

Radio amateurs and electronics engineers (especially on the Internet) often advise beginners to use acid. This is a fatal mistake.

This flux is easy to tin, but the cost of using such active substances is high.

Advantages and disadvantages of acid

Advantages:

Good tinning of oxidized surfaces;
Low price.

It removes oxides perfectly, is available in any radio store, and acetylsalicylic acid is available in a pharmacy.

Flaws:

The products released during acid soldering are very dangerous (especially if they come into contact with the skin or mucous membranes);
Residues of acids at the soldering site can damage the connection over time if they are not washed off in time;
Acid has high electrical conductivity - and this is a short circuit.

Active flux has major disadvantages that are not equal to the advantages.

Radio amateurs most often solder radio components, wires, and printed circuit boards. All this is well soldered with ordinary rosin. At most, a small oxide film may form on the parts due to the oxidation reaction in air, but it is not as critical as oxides from water.

Popular mistakes

Why is it easier to solder with soldering acid? During heating, the soldering area becomes covered with oxides faster, since the higher the temperature, the faster the chemical reactions proceed. Acid also begins to corrode these oxides faster. Here lies another problem. Acid also corrodes the soldering joint, in addition to oxides. This degrades the strength of the connection.

For what reason is soldering with rosin or any other simple flux more difficult? They do not contain active acids, but this does not interfere with excellent soldering without acid.

Poor soldering is preceded by many errors:

Overheat. The flux evaporates and does not have time to take part in soldering. This happens when the temperature on the soldering iron is set above 300 degrees;
Underheating This occurs due to the small heating area, lack of understanding of the principles of soldering work, or poor-quality equipment;
Long touch of the soldering iron to the contact point. Soldering should not last more than a few seconds. Otherwise, most of the flux will evaporate, and the rest of the solder will form a lump and begin to oxidize.
Amount of flux and solder. An excess or deficiency of components is also a critical factor. Too much flux - the solder will start to spread, too little - it will evaporate quickly and will not be enough for the entire area.

How to solder without acid

To solder efficiently and correctly, just follow simple rules:

Do not overheat the soldering area. If it seems that tinning and melting the solder is going slowly, it is better to try another tip, try heating the air with a hair dryer to one hundred degrees (on top of the hair dryer, near the soldering point). Under no circumstances should you increase the temperature on the soldering iron to 400 degrees, this will only worsen the situation. Solder at such temperatures begins to evaporate rather than melt, let alone flux.
Assess the situation. For example, some parts or connectors cannot be tinned well without heating. In especially severe cases, you can even lightly walk over the contact with the softest and most gentle sandpaper. There is such a problem with homemade boards when they are not soldered for a long time after production. Copper traces are plated with copper and are more difficult to tinn than before.
Safe soldering. Soldering should only be done in a ventilated area. Even the products of rosin evaporation are not very useful, let alone other fluxes, especially soldering acids. When soldering, you must maintain a distance, otherwise a drop of solder may accidentally get on your skin or mucous membranes.

For example, for soldering twisted pairs, a medium tip of the mini wave type and alcohol rosin are suitable. Soldering time is no more than 5 seconds. Is the contact not soldered? Wait until the soldering area has cooled down, apply flux again, and smoothly go over the soldering iron.

For complex cases, LTI-120 is sufficient. This is an activated flux (not active and acid free)

Active flux should only be used as a last resort. Even strong oxides, ordinary acid-free fluxes perfectly clean and tin. There is no need to use any aspirin tablets, acids, or F-38N. To solder the same wires, ordinary rosin is enough.

How to wash off soldering acid

You can remove residues with Galosh gasoline, isopropyl alcohol or soda solution. This can be done using brushes, cotton pads or sticks. It is necessary to carefully remove flux residues without splashing.

Source: https://tyt-sxemi.ru/kislota-payalnaya/

Do-it-yourself soldering acid: composition and purpose, do-it-yourself production - Machine

Soldering acid is a flux that can be classified as a separate category, because it has an aggressive effect on materials that are needed during work. This flux mainly spreads in a liquid state, and this does not depend on its concentration. Sometimes you can purchase a concentrated substance and then dilute it, or perhaps buy a ready-made, diluted one. In addition, everyone can easily make soldering acid on their own.

The properties of materials must be selected according to those factors that are necessary for their use.

Soldering acid is intended for those metals that are heavily contaminated, because oxidation occurs on them, and a large amount of rust remains on the surface.

The material is very active, so it is necessary to work with it carefully and avoid contact with human skin and mucous membranes. You must first carefully familiarize yourself with the rules and methods of using acid, and only then begin to use it for its intended purpose.

In the process of producing soldering acid yourself, it is necessary to use special technology. In the end, the result should be a material that will have the properties prescribed by GOST. This is what will make the flux high-quality and reliable so that the connections are strong.

It is necessary to ensure that the properties and functions of the acid work even after soldering the metals, because the material removes films and rust from the surface, and also prevents their reappearance.

You should also take into account the spreadability of the materials being soldered over the surface and the adhesion to metals and products.

Characteristics, composition and properties

It is necessary to know exactly what the material should consist of, and only then begin its production. Soldering acid includes:

wetting additive;
ammonium chloride;
deionized water;
zinc chloride;
hydrochloric acid.

Soldering acid, created independently, may consist of other components. You just need to do everything to ensure that the flux has all the necessary properties. It is necessary to ensure high activity of this material.

It must interact with the necessary materials in a minimum amount of time, and also destroy all substances that prevent normal soldering. However, it is worth considering that small parts may be damaged and deteriorated when exposed to acid.

Solder active fat has the same properties.

The acid has a rather unpleasant odor, so when a person inhales it, his health may suffer. That is why it is recommended to use a respirator when working with this material.

Well, the work area must be constantly ventilated.

It is necessary to protect your hands, skin and mucous membranes from acid; it is necessary that the workpiece gets only into the places necessary for soldering.

Materials and tools for making acid

You need to know that the soldering acid you make yourself will have a slightly different composition than the purchased one. However, it will be simpler. To prepare such acid, you need to use some equipment:

Glass container or jar for mixing and preparing the material.
Zinc granules or cups from used batteries containing this element.
Tap clean water.
Concentrated hydrochloric acid, which is capable of dissolving unnecessary impurities and substances.

Making acid yourself

First you need to take a container or jar for mixing the acid. This is where the zinc or batteries and their remains are placed.

Only after all of the above can hydrochloric acid be poured into the container. The main thing is to act with great caution, because if it comes into contact with the skin, you can get a serious burn.

The acid in the container should not be more than 3/4 of the volume of the entire composition.

As a result, it turns out that the proportions should be like this. For 1 liter of hydrochloric acid, 412 grams of zinc are needed, but this can only be measured using special tools. Therefore, it is worth knowing that there will be some deviations in one direction or another.

When further preparing soldering acid, you must wait for the reaction of the chemicals to finish. Zinc and acid come into contact with each other, the metal gradually dissolves. During this process, active hydrogen evolution occurs, so many bubbles can be seen in the liquid.

The liquid gradually becomes clearer and cleaner. When all processes are completed, it is necessary to pour the liquid into a tightly closed container. All these materials can be easily purchased in stores specializing in the sale of chemicals and reagents. When using batteries, you can see that almost any of them will do.

If you need to make a material with weaker properties, then you should slightly reduce the aggressiveness. In this case, it is recommended to add a little water to make the solution more liquid and with weaker properties.

However, you need to be careful, because the liquid can splash and get on the skin and mucous membranes of a person.

In this case, you should choose the proportions yourself, adhering to the specifics of the required soldering.

Making soldering acid yourself

First, you should take care of your own safety, because using acid is very dangerous and can cause irreparable harm to your health. If acid production is carried out in enterprises and industrial areas, then everything must be done in special-purpose cabinets.

The reagents are reliably protected from outsiders, and they are poured strictly under special hoods. At home, it is recommended to use protection, gloves, goggles, respirators and other devices. Dissolving the acid should only be done in a well-ventilated area or even outside.

Indeed, in the process of creating acid for soldering, hydrogen is constantly released into the air in large quantities. It is also necessary to take care, just in case, of water, with which you can quickly rinse the area of skin on which the substance has come into contact.

It is best to use cold tap water because in the event of an accident, it will reduce pain and quickly clean the wound.

If this substance is spilled on the surface, it is best to wash it off with a special mixture of water and alkali.

You must also remember that this material must be stored correctly, the container must be closed and sealed, storage is carried out in a dark and cool place.

It is recommended to prevent unauthorized people from accessing the soldering acid to avoid danger to others. Flux is sometimes made from pure hydrochloric acid without zinc and water. However, it is mostly used only for iron products.

Source: https://regionvtormet.ru/beton/payalnaya-kislota-svoimi-rukami-sostav-i-prednaznachenie-izgotovlenie-svoimi-rukami.html

What is soldering acid used for? :

Welding and soldering are two opposing processes that join metal parts together. When welding, due to the high temperature and melting of the metal, the surfaces of the parts are connected. Soldering acid allows you to firmly connect parts in a completely different way. Every technician who repairs various equipment at home should know what this substance is.

The essence of soldering acid

Soldering acid can be used to join surfaces of different materials by introducing molten material between the parts. It's called solder. It has a lower melting point than metal.

The solder should be evenly distributed over the surface of the elements and provide good adhesion to the base. After cooling, it hardens and provides an inextricable connection between the workpieces.

The effectiveness of the presented process depends on the cleanliness of the substrates on which soldering will be applied. Soldering acid is used to prepare the surface of parts. Without it, the process will not proceed satisfactorily, and the required result will not be achieved.

What is soldering acid used for?

To perform its direct functions, the presented substance performs a number of actions. It initially cleans the surface of the workpiece from dirt and oxides. In addition to its main function, the acid prevents the appearance of traces of oxidation in the future on various types of parts.

By reducing the surface tension of the solder, soldering acid helps it spread more evenly over the surface. This leads to a reliable connection of parts.

For different metals, suitable types of soldering acid are used. It should also be taken into account that such a substance is a good conductor. Therefore, if it is undesirable for electric current to pass through this path, the electrical flow pattern should be calculated.

Types of soldering acid

To understand how to solder with soldering acid, you should consider its varieties. There are liquid, powder or paste fluxes (as soldering acid is sometimes called).

At home, soldering acid is most often used for soldering copper, silver, brass, nickel and their alloys - rosin. This substance is obtained from the resin of coniferous trees. This happens by evaporating the turpentine from it.

To solder cast iron, steel and iron, you will need an aqueous solution of zinc chloride. This soldering acid contains ZnCl. Zinc chloride is prepared by melting zinc metal in hydrochloric acid.

Orthophosphoric soldering acid is quite common. Its composition contains 1/3 ethyl alcohol. This substance is fireproof. However, it should be stored strictly in accordance with the manufacturer's instructions.

Making at home

The substance presented is freely available for sale. However, craftsmen still wonder how to make soldering acid at home. This is quite easy to do if you have the appropriate chemicals.

This will require zinc, hydrochloric acid in the proportion of 412 g of Zn and 1 liter of HCl. Zinc is placed in a glass, porcelain or ceramic container. Then hydrochloric acid is added to the laboratory glassware. This should be done very carefully. Hydrochloric acid in the container should not exceed ¾ of its volume.

To understand how to make soldering acid, you should familiarize yourself with the chemical reaction. As a result, hydrogen will be formed (bubbles will come out). When this stops, the liquid will lighten and become clear. After this, it is poured into another container and tightly closed with a lid.

How to replace soldering acid

If you cannot find soldering acid at home or even the ingredients for its preparation, you can replace it with aspirin or acetylsalicylic acid. It is necessary to work with such flux in a well-ventilated area. When heated, aspirin releases caustic fumes, so the technology for using such a substance differs from the usual one.

To tinning the part, it is sprinkled with acetylsalicylic acid powder. Sometimes the wires are placed on a tablet and heated with a soldering iron.

When deciding what to replace soldering acid with, you should pay attention to VTS flux. It is made on the basis of salicylic acid. VTS reliably protects parts from corrosion, so it is often used in repair work.

How to use soldering acid

To understand how to use soldering acid, you should refer to the technology of its application. Depending on the manufacturer, substances differ in the method of application. This could be a dropper-shaped neck or a jar with a brush. If the product is not equipped with special means for applying it to the part, you can even use just a piece of paper rolled into a tube.

The part must be cleaned before applying acid. This is best done with a file or sandpaper. The application of a substance such as soldering acid requires serious attention. How to use it is necessarily indicated by the manufacturer in the instructions.

The substance should be evenly distributed throughout the part. At the end of the work, any flux is removed from the surface of the part. This is necessary to prevent accelerated oxidation of the surface of the workpiece and the solder itself.

You can remove acid using water or soda solution. Residues of VTS are washed off with acetone or ethyl alcohol. The soldering iron tip melts a little solder and transfers it to the surface.

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