How to properly solder with a soldering iron using rosin. How to learn how to solder correctly with an electric soldering iron: operating rules Preparing a soldering iron for soldering
Soldering - technological process connections of metal parts that have existed for more than one millennium. It was originally used by jewelers to create jewelry. After all, forge welding, already known in those days, was not suitable for jewelry making, and the process of soldering metals using low-melting alloys-solders turned out to be just right. Gold was soldered using silver-copper solders, silver - copper-zinc, and for copper the best composition was an alloy of tin and lead.
Over time, with the development of electrical engineering and then radio electronics, soldering became, and remains to this day, the main method of assembling parts to create various circuits. Robotic conveyor systems have appeared, automatically, without manual labor, producing hundreds of printed circuit boards and components of modern equipment per hour, the main assembly method of which is soldering. But the good old hand soldering iron has not lost its relevance today.
And over the years it has undergone many changes and improvements.
- It all started a long time ago with massive soldering irons and hammers heated over fire or coals. The once widespread gasoline blowtorches even had special holders on top for heating these hammers. With such a soldering iron it was quite possible to solder a leaky kettle or samovar. And amateur fishermen, who made all their own equipment in those days, used them to make spinners and jigs, which provided catches no worse than modern wobblers and twisters.
- In the 20s of the 20th century, when radio and electrical equipment began to become widespread, an electric soldering iron was invented. At first it also looked like a hammer, but then it came to its classic rod form, in which it still exists.
- The classic design of the electric soldering iron lasted quite a long time. It is good for heater powers in the range of 25~200W. But the miniaturization of electronic equipment has placed new demands on these devices. There is a need for low-power tools that heat up quickly and allow you to instantly regulate the temperature of the tip.
- Pulse soldering irons, in which the tip is part of the circuit of the secondary winding of the transformer, wound with a very thick wire, have gained some popularity. The voltage in such a winding is very small, but a current of several amperes flows through it, which leads to strong heating.
- A more exotic option are induction soldering irons, in which the ferrite thermal rod is heated by high-frequency induction currents. Temperature regulation in them occurs automatically due to changes in the magnetic permeability of the rod when it is heated to the Curie point.
- Modern models of gas soldering irons have evolved from the original idea of heating a blowtorch with a burner. In them, the tip is heated by a gas burner located directly in the body of the tubular rod. The gas comes from a refillable cartridge located in the handle.
It is a handle made of thermally and electrically insulating material through which an electric wire passes, connected to a tubular heating element fixed at its other end. A rod-tip is inserted into the tubular heater, with the help of which soldering is actually carried out. As heating element Traditionally, a nichrome spiral is used, wound on a layer of asbestos insulator. The tip is a copper rod sharpened at the end accordingly.
Therefore, in a traditional electric soldering iron, the inertial nichrome thermoelement was replaced with a ceramic one. In such devices, a tip that is hollow at one end is placed on a heated ceramic rod. Due to good thermal contact and low thermal dissipation, the tip heats up almost instantly, and the temperature meter located in close proximity to it allows you to set the degree of heating with high accuracy.
In addition, these models of soldering irons are much more durable than conventional ones, which is very important for the conveyor assembly of radio equipment.
They are usually made in the form of a pistol with a trigger toggle switch that allows you to turn on the flow of current for a few seconds. This is enough to bring the tip to operating temperature. The disadvantage of such devices is the impossibility of accurately adjusting the temperature; however, they are quite convenient for domestic use.
They are good for autonomous operation in the absence of electricity. The tip of such soldering irons is easily removable; when removed, the device turns into a miniature gas burner, which can be used for soldering with high-temperature solders.
As mentioned above, the connection of parts during soldering is done using special metal alloys - solders, of which there are a great variety, for all occasions. But basically they can be divided into two large classes:
- Low temperature or soft. Melting point less than 350°C. In turn, they are divided into several types:
- Tin-lead. The number in their designation shows the percentage of tin: POS‑18 (melting point - 277°C), POS‑30 (256°C), POS‑40 (235°C), POS‑50 (222°C), POS‑ 61(190°C), POS‑90 (222°C). For the installation of radio-electronic products, POS-61 or its imported analogs, for example, 60/40 Alloy, are most widely used. For other applications, including household ones, which do not require very high quality connections, POS‑30 is most often used.
- Tin-free - lead(327°C), lead-silver (304°C).
- Low-melting - Wood's alloys(60.5°C), d'Arsenval (79.0°C), Rose (97.3°C).
- Special, for example, for soldering aluminum - Avia-1 (200°C), Avia-2 (250°C).
Represented by several classes:
- Copper (1083°C)
- Copper-zinc or brass (830~870°C)
- Copper-phosphorus (700~830°C)
- Silver (720~830°C)
Tin-lead solders are most widely used in many areas of industry and everyday life. They are available in the form of rods or wire. For use in the installation of radio-electronic products, tubular solders are used in the form of a wire with a flux filler in the middle.
Fluxes are special compositions designed for cleaning and tinning the surfaces of parts connected by soldering. Tinning is the process of pre-coating parts with solder, facilitating their final connection. It is necessary and recommended in soldering technology, since surfaces covered with layers of oxides and contaminants will not provide a reliable connection with the solder, and, therefore, a high-quality solder joint result. To remove such oxides and contaminants, fluxes are used:
- Non-acidic. The most famous and, perhaps, still one of the best fluxes was and remains ordinary rosin, or purified pine resin. Most special fluxes produced for use in the radio-electronic industry also contain it. Nothing better has yet been invented for soldering electronic circuits. It is the rosin that is contained inside the solder rod. Its advantage is that after soldering it is easily removed and does not create an aggressive environment that has a destructive effect on the solder joint over time.
- Chemically active. They contain acids, so they require thorough rinsing of the joint after soldering. Most known formulations contain zinc chloride. They are mainly used for joining products made of ferrous and non-ferrous metals.
To solder with rosin, it can be used both in its original form and in an alcohol solution. Of the compositions produced by industry, it is contained in radio technical fluxes “LTI-120”, “Rosin-gel”, etc.
Active fluxes include F-34A, FSGL, “Glycerin-hydrazine”, etc.
Auxiliary materials
When starting to solder radio components, you should carefully prepare workplace. It should be well lit and have good ventilation, because this work usually produces quite a lot of acrid smoke and gases.
It’s a good idea to have a small vice, a magnifying glass with a third-hand clamp, and a vacuum suction for solder in your tools. You also need to keep on hand tweezers, an awl, pliers or duckbill pliers, side cutters, a small file or needle file, pieces of sandpaper, rags and a sponge. Before starting soldering, all tools, devices and reagents should be conveniently laid out at the workplace.
Soldering temperature
The soldering temperature should not exceed - 250°C; when soldering radio components, the heating of the tip should not rise above 300°C. A soldering iron without a temperature controller may, during prolonged operation and surges, mains voltage heat up to 400°C. If the equipment does not include a special soldering station, it is advisable to purchase a regular dimmer at an electrical goods store to lower the temperature, which is used to adjust the brightness of the light. Moreover, with the widespread transition to economy lamps that do not work with it, the demand for it, and accordingly, prices are reduced.
With a regular copper tip without special coating, when soldering, especially at elevated temperatures, the copper oxide formed on the rod dissolves in the mixture of solder and flux. At its working end, recesses and cavities are formed, due to which its destruction is further accelerated and the quality of soldering deteriorates.
Therefore, before starting work with a soldering iron and during the process, they must be removed. To do this, you need to clean the working part of the tip with a file, giving it the required shape: a cone, a flat screwdriver or a beveled cut.
After turning on the soldering iron and waiting for it to warm up, the tip, stripped to a red copper color, must be tinned. It's not that difficult. It is enough to dip its working end in rosin and melt a small piece of solder placed on a soldering iron stand or other metal surface.
Then, in the molten solder, rub the working edges of the tip on the metal of the stand until the end of the rod is covered with an even and uniform layer of solder. The soldering iron should be fairly well heated, which is indicated by easy and rapid softening of both rosin and solder.
As soon as you start working, the soldering iron tip gradually begins to burn, even if you do everything correctly. This is evidenced by its blackening and coating with scale, so the cleaning and tinning process should be repeated periodically. In order not to remove a lot of copper with a file, you can clean the rod at this time by rubbing it on a piece of sandpaper laid out on the table, and then tin it again.
All this does not apply to special fireproof rods. They cannot be cleaned with a file. Moreover, their nickel-plated shiny layer must be carefully protected from damage and scratches. However, such soldering irons also need to be tinned during operation. But for them this procedure is not so simple and requires skill.
To do this, you need to clean them from plaque formed at high temperatures by rubbing them vigorously on a special sponge or a slightly damp piece of terry towel, and then immediately dip them in rosin and in its melt, rub it against the tip with a solder rod.
Preparing parts for soldering
In order to properly glue two parts, you need to lubricate them with glue, wait a little, lubricate them again, and then squeeze tightly. The same is true in the soldering process: to obtain a high-quality connection, the parts should first be tinned - covered with a thin layer of solder. This process requires certain experience and knowledge. For each type of material connected by soldering, there is its own technology.
Tinning is an integral part of the process
To facilitate their installation, the leads of most radio components leave the factory already tinned. However, before installing them on the board, they should be re-coated with a layer of solder. There is no need to clean it again; it is enough to take a drop of solder on the soldering iron tip and distribute it evenly over the pins of the parts.
In order to solder copper wires efficiently and correctly, you should start with tinning without insulation. They should first be cleaned with sandpaper, then dipped in rosin heated with a soldering iron or, lubricated with an alcohol solution, covered with molten solder.
Copper wire in enamel insulation must first be cleaned by removing the coating with sandpaper or scraping it off with a knife blade. For thin wires this is not so easy. Their insulation can be burned in the flame of a torch or lighter, but this significantly reduces the strength of the wire itself.
You can use a proven method: place the end of the wire on a domestic aspirin tablet (imported ones are most often not suitable) and, pressing the heated tip of a soldering iron, drag it several times over the molten preparation.
It must be said that this procedure literally eats up the soldering iron tip. In addition, this produces very caustic smoke, inhaling which can burn the respiratory organs, so you should resort to this method as a last resort.
To service parts made of ferrous metals, bronze and others, it is necessary to use active fluxes. For such connections, low-melting and high-quality radio solders are not required - you can also use the usual, cheaper POS-30.
Having carefully sanded the surfaces before soldering, you need to coat them with flux, for example, zinc chloride, warm them well and thoroughly tin the joints. After this, having once again warmed up both surfaces to be connected, solder them, pressing them tightly against each other, and then fix them until the solder cools. The more massive the parts, the more powerful the soldering iron is needed. During soldering, you need to try not to move them, since massive parts hold the temperature for a long time.
Aluminum should be soldered with special solders using special fluxes. True, having gained a little experience, you can join with ordinary solder. But this only works for pure metal, and many aluminum alloys are very difficult to solder.
Let's take a closer look at the soldering technique with a soldering iron.
Radio components prepared for soldering need to be inserted into the holes of the board, shortened with wire cutters to the required length and, having been heated with a soldering iron along with the trace of the printed circuit board, bring a solder rod to them, and when a drop of it spreads in an even layer over the soldering area, remove the soldering iron and wait for the solder to cool. also trying not to move the parts out of place at this time.
Soldering of miniature transistors and microcircuits should be done especially carefully, trying to prevent them from overheating. When assembling chips, it is best to first solder the power and ground pins, wait for the solder to solidify reliably, and only then, touching the soldering iron and the solder rod for a split second, unsolder all the other pins. You can first lubricate the soldering areas with an alcoholic rosin solution, this will significantly improve the quality of the connections.
The main conditions for high-quality soldering are good stripping and tinning before connection, and good heating during it. The half-solder at the soldering site must be completely melted on both parts - this will ensure a reliable connection. But at the same time it should not be overheated. The skill of good soldering lies in finding that optimal balance that will ensure the highest quality of work.
Soldering safety precautions
The release of caustic gases during soldering has already been mentioned. The work area should be well ventilated and ventilated. The soldering process may be accompanied by splashes of hot solder and flux, so you should beware of burns, and especially take care of your eyes. It is best to use safety glasses for this. And simply by accidentally touching a hot instrument with exposed parts of the body, you can get a severe burn.
Most electric soldering irons, except battery and low-voltage ones, operate on mains voltage, so when working with them it is strictly necessary to follow all electrical safety rules.
You should not disassemble the soldering iron - then, after assembly, there is a danger of insulation damage and breakdown high voltage on his body, and this is already extremely dangerous.
When working, you must also monitor the power cord of the soldering iron. Contact with a hot tip may cause damage to the wire insulation and risk of shock. electric shock. It can also lead to a short circuit and fire.
Learn how to use a soldering iron correctly from this video
The most interesting thing is that all types of soldering irons that have appeared throughout their existence are still used today.
How to connect two massive parts by soldering field conditions when electricity is unavailable, or there is no suitable electric soldering iron? A hammer soldering iron heated over a fire or with a blowtorch can help.
And an old 100-W electric soldering iron gathering dust in the closet, unsuitable for working with modern electronic circuits, is quite capable of repairing brass or bronze items or jewelry.
For those who are interested self-production jewelry, a universal gas soldering iron-torch will become an indispensable assistant.
The art of soldering must be learned gradually. Starting from soldering wires and moving on to printed circuit boards, each method has its own subtleties both in the selection of consumables for soldering and in technology. Today we will share with readers the basics of soldering and basic work skills.
What is the essence of soldering
Soldering uses the ability of some metals in a molten state to effectively flow over the surface of others under the influence of gravity and moderate surface tension. The connection by soldering is permanent: the two parts being connected are, as it were, enveloped in a layer of solder and remain motionless after it hardens.
Since we will consider soldering specifically in the context of metal soldering, the most important parameters will be mechanical strength and conductivity electrical connection. In most cases, these are directly proportional values and if two parts are tightly grasped, then the conductivity between them will also be high. However, solder has resistivity higher than even that of aluminum, so its layer should be as thin as possible, and its hiding power should be as high as possible.
In order for soldering to be possible in principle, there are two conditions. The first and most important thing is the cleanliness of the parts at the soldering site. Solder attaches to the metal surface at the atomic level and the presence of even the slightest oxide film or contaminants will make reliable adhesion impossible.
The second condition is that the melting temperature of the solder must be significantly lower than the temperature of the parts being soldered. This seems obvious, but there are solders with a melting point higher than aluminum, for example. In addition, if the actual difference in melting temperatures is not high enough, when the solder solidifies, thermal shrinkage of the parts may prevent normal formation crystal lattice solder.
Fluxes and solders - how to choose the right ones
For the reasons described above right choice flux and solder are almost half the success in the soldering business. Fortunately, there are quite universal brands suitable for most tasks. The area of application of almost all fluxes and solders is clearly indicated on the labels, but some aspects of their use still need to be known.
Let's start with fluxes. They are used for etching parts, removing and dissolving the oxide film with further protection of the metal from corrosion. As long as the surface is covered with flux, you can be sure of its cleanliness, as well as that the molten tin will wet it well and spread.
Fluxes are distinguished by the type of metals and alloys of the parts being joined. Basically, these are mixtures of metal salts, acids and alkalis that actively react when heated with a soldering iron. Well, since there are quite a lot of oxide forms and contaminants, the cocktail must be specially selected for a specific type of metals and alloys.
Conventionally, soldering fluxes are divided into two types. Active fluxes are created on the basis of inorganic acids, mainly chloric and hydrochloric. Their disadvantage is that they need to be washed off immediately after soldering is completed, otherwise acid residues cause quite severe corrosion of the connection and themselves have a fairly high conductivity that can cause a short circuit. But you can solder almost anything with active fluxes.
The second type of flux is created primarily on the basis of rosin, which can also be used in its pure form. Liquid flux is much more convenient to apply; it also contains alcohol and/or glycerin, which completely evaporate when heated. Rosin fluxes are the least effective when soldering steel, but for non-ferrous metals and alloys they are mainly used or other compounds of organic chemistry. Rosin also requires rinsing because in the long term it promotes corrosion and can become conductive by picking up moisture from the air.
Liquid and solid rosin
With solders everything is somewhat simpler. Lead-tin solders of the POS brand are mainly used for soldering. The number after the marking indicates the tin content in the solder. The more it is, the higher the mechanical strength and electrical conductivity of the connection and the lower the melting temperature of the solder. Lead is used to normalize the solidification process; without it, the tin may crack or become covered with needles.
There are special types of solders, primarily lead-free (BP) and other non-toxic ones, in which lead is replaced by indium or zinc. The melting point of BP is higher than that of conventional ones, but the connection is stronger and more resistant to corrosion. There are also low-melting solders that spread already at 90-110 ºС. These include Wood and Rose alloys; they are used for soldering components that are sensitive to overheating. Special solders are mainly used in soldering radio equipment.
Power and types of soldering irons
The main difference between a soldering tool is the type of its power source. For ordinary people, the most familiar are network soldering irons powered by 220 V. They are used mainly for soldering wires and more massive parts, because they can overheat copper wire almost impossible, except perhaps for melting of the insulation.
The advantage of networked soldering irons is their high power. Due to it, high-quality and deep heating of the part is ensured, plus it does not require a bulky power supply for operation. Among the disadvantages, we can highlight the low ease of use: the soldering iron is quite heavy, the tip is located far from the handle and such a tool is not suitable for fine work.
Soldering stations use thermal control to maintain a stable temperature level. Such soldering irons do not have significant power, usually 40 W is already the ceiling. However, for heat-sensitive electronics and soldering small parts, this tool is best suited.
Choosing a tip and caring for it
Soldering iron tips are distinguished by shape and material. The shape is simple: the most primitive and at the same time universal is the awl-shaped sting. Variations are possible in the shape of a spatula, a cone with a blunt end, with a bevel, and others. The main task when choosing a shape is to achieve the maximum area of contact with a specific type of parts to be soldered, so that the heating is powerful and at the same time short-lived.
In terms of material, almost all tips are copper, but they come with or without coating. Copper tips are coated with chromium and nickel to increase heat resistance and eliminate oxidation of the copper surface. Coated tips are very durable, but are slightly less wet with solder and require careful handling. To clean them, brass shavings and viscose sponges are used.
Uncoated tips can rightfully be classified as consumables for soldering. During operation, such a tip periodically becomes covered with a layer of oxides and the solder stops sticking to it. The working edge needs to be re-cleaned and tinned, so with intensive use the tip wears off quite quickly. To slow down the burning of the tip, it is recommended to first forge it and then sharpen it to give the desired shape.
Soldering wires
Soldering wires is the easiest. We dip the ends of the cores into the flux solution and run a soldering iron along them, the tip of which is generously moistened with flux. During the tinning process, it is advisable to shake off excess molten solder. After application, half wires are formed into a twist, and then thoroughly heated with a small amount of solder, filling the free space between the wires.
Another method is also possible, when before twisting the wires are simply thoroughly moistened with flux and soldered without prior tinning. This method is especially popular when soldering stranded conductors and small-diameter wiring. If the flux is of high quality, and the soldering iron provides sufficiently strong heating, even a twist of 3-4 “fluffy” wires of 1.5 mm 2 each will be well saturated with tin and will be reliably soldered.
Please note that in electrical installation, that is, inside distribution boxes, soldering wiring is not accepted. Primarily due to the inseparability of the connection, plus the solder has a significant contact resistance and there is always a high risk of corrosion. Wires are soldered exclusively for connections inside electrical appliances or for tinning the ends of stranded wires before tightening them with screw terminals.
Working with electronic components
Soldering electronics is the most extensive and complex topic that requires experience, skills and special equipment. However, even an amateur can replace a faulty element on a printed circuit board even with only a network soldering iron.
Lead-out elements (those with legs) are the easiest to solder. They are preliminarily fixed (plasticine, wax) with pins in the holes of the board. Then, on the reverse side, the soldering iron is pressed tightly against the tail to warm it up, after which a solder wire containing flux is inserted into the soldering site. You don’t need too much tin, just enough so that it flows into the hole from all sides and forms a kind of elongated cap.
If the lead element dangles and needs to be held by hand, then the soldering area is first moistened with flux. A very small amount is needed; here it is optimal to use bottles of nail polish, pre-washed with acetone. With this soldering technique, tin is collected on the soldering iron in a small amount and a drop of it is carefully brought to the terminal of the element 1-2 mm from the surface of the board. The solder flows down the leg, uniformly filling the hole, after which the soldering iron can be removed.
It is very important that the parts to be joined remain motionless until the solder has completely cooled. Even the slightest violation of the shape of tin during crystallization leads to the so-called cold soldering - crushing the entire mass of solder into many small crystals. Characteristic sign This phenomenon is a sharp clouding of the solder. It needs to be reheated and wait until it cools evenly, completely still.
Poor quality, cold soldering
To maintain tin in a liquid state, it is enough for the soldering iron to contact the tinned surface of the tip with any point in the moistened area. If the soldering iron literally sticks to the parts being soldered, this indicates a lack of heating power. For soldering heat-sensitive semiconductor elements and microcircuits, regular solder can be mixed with fusible solder.
Soldering of massive parts
Finally, we'll briefly talk about soldering parts with high heat capacity, such as cable joints, tanks or cookware. The requirement for the immobility of the joint is most important here; large parts are pre-connected with clamps, small parts with lumps of plasticine; before soldering the joint, it is grabbed pointwise in several places and the clamps are removed.
Massive parts are soldered as usual - first, solder at the joint, then fill the seam with liquid solder. However, special solder is used for these purposes, usually refractory and capable of maintaining high tightness, as well as withstanding partial heating well.
When soldering like this, it is extremely important to keep the parts well heated. For these purposes, the soldering seam immediately before the soldering site is heated with a gas burner, and instead of a conventional electric soldering iron, a massive copper hatchet is used. It is also constantly heated in the flame of a burner, simultaneously wetting it with solder, and then the joint is filled, partially melting the previous seam by a few millimeters.
A similar heated soldering technique can also be used when working with a regular soldering iron, for example, when soldering thick cable cores. The sting in this case acts only as an operational tool for carefully distributing the tin, and the main source of heating is a gas burner.
How to solder with tin? Soldering is the formation of mechanical contact between metal surfaces. Tin often acts as solder - a “gasket” between the surfaces of parts that holds them together. To solder two parts, it is not enough to heat the surface with tin and attach the second part to it, like glue.
The temperature of the surfaces must be different. It's better to buy a soldering station. The price for it is about 1000 rubles and more. You can get the following benefits if you work not with a soldering iron, but with a soldering station:
- The heating temperature at the soldering station is regulated;
- the tip does not burn out, so the set temperature during operation is maintained constantly;
- The soldering station usually has a heat-resistant tip;
- There are antistatic soldering stations. This property is indispensable if you are going to solder field elements. An antistatic soldering station costs $150-200;
What you need to solder tin
In addition to a soldering iron, you will also need flux to remove oxides. Well, tin will be solder - the “glue” for joining metal parts.
Which flux should I choose? Previously, they soldered with rosin. But it’s difficult to wash off the remaining rosin, especially if the board is soldered. Especially if the gaps are small: dendrites grow.
On the modern market you can easily find a large selection of alternative fluxes to rosin. They are washed off with water and do not harm the soldering iron tip. For convenience, such fluxes are also packaged in syringes. And the price may vary - it’s quite possible to find inexpensive ones.
Pure tin solder is practically not used today. Multi-channel solder is sold in coils and reels. This means that there is already flux inside the tin wire!
And in small jars you can find a sting activator. Before starting soldering, it must be tinned. It is also necessary to do this after soldering.
Also, for soldering with tin you will need a knife and pliers. We begin to prepare the workplace. Take a disposable plate. It will serve for waste. Take care of the lighting. Tin the contact surfaces of the parts. You need to take flux and then apply tin using a soldering iron. The tin from the soldering iron will flow around the contact pad even with a light touch if the temperature has been selected correctly. Remove any remaining flux.
The ability to solder well is quite difficult to acquire. You'll have to practice, but the results are worth it.
We hope you now know how to solder with tin, or at least we helped with advice. If you have any questions, ask them in the comments.
The soldering process itself is not complicated - we prepare the parts, treat them with flux, heat them up, and add solder in the soldering area. But, as in any business, there are some nuances that you need to know in order to get a quality result.
What is the soldering process?
Soldering is performed when two parts need to be joined.
Before the process, it is necessary to prepare the components: clean them from dirt and remove the oxide film at the soldering site, since the presence of even slight dirt or oxidation will prevent reliable joining of the materials.
When choosing solder you need to follow the rule - temperature regime The melting point of the solder must be lower than the melting temperature of the elements that are planned to be connected.
Procedure for soldering technology:
The surfaces of the parts must be cleaned of dirt, rust, oxide film, etc., so that the base metal shines. To remove oxidation and prevent it in the future, it is necessary to coat the parts at the joint with flux. You can apply it with a brush in a thin layer.
An alternative to the second step is a processing option called tinning. Mainly used for processing wires. The stripped wire is placed on rosin, heated with a soldering iron, the wire must be turned so that it is all in the molten rosin, then a thin layer of molten solder is applied, which chemically connects with the base metal (you can take a drop of solder directly with a soldering iron and apply it to the part).
The parts are connected mechanically: for example, when working with wires, you need to twist them; The output elements on the board are fixed with plasticine, wax or hot glue; other parts can be clamped with pliers or a vice.
Additional flux is applied to avoid oxidation when heated. Solder is applied with a heated soldering iron.
For ease of understanding, we attach photo instructions on how to solder correctly.
Types of soldering irons
In everyday life, networked soldering irons operating on a voltage of 220 V are common.
Professionals prefer soldering stations. Their main advantage is the presence of a thermostat, thanks to which the set temperature is stably ensured.
In the case of network soldering irons, the temperature is determined by the rosin or flux; when the soldering iron is ready for use, they begin to boil well, but should not be allowed to burn.
For home use, you can purchase two soldering irons with low (40-60 W) and medium power (100 W). A low-power soldering iron is designed for soldering parts in electronics.
Consumables
Flux
This is a mixture for removing oxidation from metal parts before the soldering process. Flux treatment allows the solder to better spread over the joint and protect it from corrosion when heated. Flux can be found in the form of liquid, paste and powder. It is, of course, more convenient to apply liquid flux.
Fluxes can be rosin, ammonia, boric and orthophosphoric acids, and regular aspirin tablets.
It is easy to find flux on sale for any type of work, and as a rule, the label already indicates how and for what materials to use it. This allows you not to engage in amateur activities, but to use an already prepared mixture, which will avoid surprises in the form of soot.
Rosin is a popular flux, has a pleasant odor when heated, and is non-toxic. How to solder with a soldering iron with rosin: you can immediately take the liquid version of rosin, it is more convenient. If we are dealing with solid rosin, then first you need to melt it with a soldering iron and apply it to the soldering site with a tip.
Rosin is suitable for soldering copper conductors, radio and electrical elements, and behaves well with gold and silver. Residues of rosin after soldering must be removed to prevent metal corrosion.
Alcohol-rosin flux (abbreviated SKF) is rosin with alcohol in proportions of one to three. It is used in the same cases as regular rosin. Easier to use due to its liquid state.
Solder
Solder has a lower melting point than the material of the elements being joined, so when hot it envelops the joint, and after cooling the two parts become one. At what temperature to solder depends on chemical composition parts and the selected solder.
Alloys used as solders:
- tin+lead
- cadmium
- nickel
- silver, etc.
Lead-tin solders PIC are most often found on the market. The abbreviation PIC is followed by a numerical value that indicates the amount of tin. The higher it is, the more tin, which has a positive effect on the strength and electrical conductivity of the future connection.
This tip will help you figure out how to solder with tin correctly; rosin is usually chosen as a flux (the most convenient option- tin wire inside which there is already rosin present).
Lead serves as a regulator of the solidification process, since tin without this auxiliary element will crack and become covered with needles. Lead can be replaced by indium or zinc (lead-free solders).
For aluminum, you will need to choose specialized flux (F-61A, F-34A) and solder (there are different options).
Soldering iron tips
Almost all tips are made of copper, available with or without coating. Chrome-plated and nickel-plated tips are more heat-resistant, durable and not subject to oxidation.
Uncoated tips require constant cleaning, since when they oxidize they stop working efficiently (the solder does not stick). And during cleaning, the tip wears off quite quickly.
The choice of tip shape depends on the task at hand, but the awl and spatula shapes are considered universal.
Shutdown
After working with the soldering iron is completed, you need to clear the solder tip, and you can turn off the soldering iron. The hot tip needs to be inserted into the solid rosin and wait for it to cool, remove the tip, the excess rosin will drain and the soldering iron, which has now completely cooled, can be put back in place.
Armed with good theoretical knowledge of how to solder correctly with a soldering iron, in practice you can achieve success in this matter.
How to solder correctly?
Before you start considering the question: “How to solder correctly?” One thing needs to be stated...
Soldering varies. You need to understand that there is a big difference in the method of soldering a hefty 2-watt resistor onto a regular printed circuit board and, for example, a BGA chip onto a multilayer cell phone board.
If in the first case you can get by with a simple 40-watt electric soldering iron, solid rosin and solder, then in the second case you will need to use devices such as a hot-air station, no-clean flux, solder paste, stencils and, possibly, a bottom heating station for the boards.
As you can see, the difference is significant.
In each specific case, you need to choose the soldering method that is most suitable for a specific type of installation. So, for soldering microcircuits in a planar package, it is better to use hot-air soldering, and for installing ordinary output resistors and large-sized electrolytic capacitors, it is worth using contact soldering with an electric soldering iron.
Let's look at the simplest rules of conventional contact soldering.
To begin with, it is enough for a novice radio amateur to master conventional contact soldering with the simplest and cheapest electric soldering iron with a copper tip.
First you need to prepare a minimum soldering kit and soldering tool. How to prepare an electric soldering iron for use has already been discussed in the article on preparing and caring for a soldering iron.
Many people believe that for soldering it is better to use a soldering iron with a non-burnable tip. Unlike a copper tip, a non-fading tip does not require periodic sharpening and tinning, since no depressions - cavities - are formed on its surface.
Burnt out soldering iron tip
(for clarity, the copper tip is pre-processed with a file).
The photo shows that the edge of the copper tip is uneven, and the resulting depressions are filled with frozen solder.
The non-burnable tip of widely used soldering irons, as a rule, has a cone-shaped shape. Such a tip is not wetted by molten solder, that is, it cannot be used to take solder onto the tip. When working with such a soldering iron, the solder is delivered to the soldering site using thin solder wire.
It is clear that using solder in pieces or rods when soldering with a soldering iron with a non-burnable tip is difficult and inconvenient. Therefore, for those who want to learn how to solder, it is better to start their practice with a regular electric soldering iron with a copper tip. The disadvantages of its use are easily compensated by such conveniences as the ease of using solders in any design (wire, rod, lump, etc.), the ability to change the shape of the copper tip.
An electric soldering iron with a copper tip is convenient because it can be used to easily measure the amount of solder that needs to be brought to the soldering site.
Cleanliness of soldered surfaces.
The first rule of high-quality soldering is the cleanliness of the surfaces being soldered. Even with new radio components purchased in a store, the terminals are covered with oxides and contaminants. But these minor contaminants, as a rule, are dealt with by flux, which is used during the soldering process. If it is clear that the terminals of radio components or copper conductors are heavily dirty or covered with oxide (greenish or dark gray), then before soldering they need to be cleaned either with a penknife or sandpaper.
This is especially true if during assembly electronic device used radio components are used. A dark coating usually forms on their terminals. This is an oxide that will interfere with soldering.
Tinning.
Before soldering, the surface of the leads must be tinned - covered with a thin and even layer of solder. If you pay attention to the conclusions of new radio components, then in most cases you will notice that their conclusions and contacts are tinned. Soldering of tinned leads is faster and of better quality, since there is no need to pre-prepare the leads for soldering.
To tin a copper conductor, first remove the insulation from its surface and clean it of contaminants, if any. Then you need to treat the soldering surface with flux. If lump rosin is used as a flux, then the copper wire can be placed on a piece of rosin and touch the wire with a well-heated soldering iron tip. First, you need to take a little solder onto the soldering iron tip.
Next, moving along the wire, we distribute the molten solder over the surface of the conductor, trying to heat the conductor itself as best and evenly as possible. At the same time, the lump rosin melts and begins to evaporate under the influence of temperature. An even coating of tin-lead solder should form on the surface of the conductor without lumps or pellets.
Melted rosin helps reduce the surface tension of the molten solder and improves the wettability of the surfaces being soldered. Thanks to the flux (in this case, rosin), the conductor is uniformly coated with a thin layer of solder. Flux also helps remove contaminants and prevents oxidation of the surface of conductors while heating them with a soldering iron.
Warming up the soldering iron tip to operating temperature.
Before starting soldering, you must turn on the electric soldering iron and wait until its tip warms up well and its temperature reaches 180 - 240 0 C.
Since a conventional soldering iron does not have an indication of the temperature of the tip, you can judge whether the tip is sufficiently heated by the boiling of the rosin.
To check, you need to briefly touch a piece of rosin with a heated tip. If rosin does not melt well and slowly spreads over the soldering iron tip, then it is not yet heated. If the rosin boils and abundant steam is released, then the soldering iron is ready for use.
In the case of soldering with an underheated soldering iron, the solder will have the appearance of a pulp, will harden quickly, and the surface of the soldered contact will have a rough appearance with a dark gray tint. Such soldering is of poor quality and quickly breaks down.
A high-quality soldered contact has a characteristic metallic luster, and its surface is smooth and shines in the sun.
Also, when soldering various radio components, you should pay attention to the areas of the surfaces being soldered. How larger area conductor, for example, a copper track on a printed circuit board, the more powerful the soldering iron should be. When soldering, heat transfer occurs and, in addition to the soldering site itself, collateral heating of the radio component or printed circuit board occurs.
If there is a significant heat dissipation from the soldering site, then it is impossible to warm up the soldering site well with a low-power soldering iron and the solder cools down very quickly, turning into a loose substance. In this case, you need to either heat the surfaces to be soldered longer (which is not always possible or does not lead to the desired result), or use a more powerful soldering iron.
For soldering small-sized radio elements and printed circuit boards with dense installation, it is better to use a soldering iron with a power of no more than 25 Watts. Typically, in amateur radio practice, soldering irons with a power of 25 - 40 watts powered by an alternating current network of 220 volts are used. When using an electric soldering iron, it is worth Regularly check the integrity of the power cord insulation, since during operation there are frequent cases of its damage and accidental melting by heated parts of the soldering iron.
When soldering or desoldering a radio component from a printed circuit board, it is advisable to monitor the soldering time and under no circumstances overheat the printed circuit board and the copper traces on its surface above 280 0 C.
If the board overheats, it may become deformed at the heating site, delamination or swelling will occur, and the printed tracks will peel off at the heating site.
Temperatures above 240-280 0 C are critical for most radioelements. Overheating of radio components during soldering can cause their damage.
When soldering parts, it is very important to firmly fix them. If this is not done, any vibration or movement will ruin the quality of the solder, since the solder takes a few seconds to harden.
In order to perform high-quality soldering of parts “on the fly” and to avoid displacement or vibration during cooling of the soldered contact, you can use a device that in the everyday life of radio amateurs is called “ third hand”.
"Third Hand"
Such a simple device will not only allow you to easily and without special effort soldering parts, but will also relieve you from burns that can be caused if you hold the parts with your hand while soldering.
"Third hand" at work
Safety precautions when soldering.
During the soldering process it is quite easy to get a burn, albeit a small one. Most often, fingers and hands are burned. The cause of burns is usually haste and poor organization of the workplace.
It must be remembered that during the soldering process no need to put in a lot of effort to the soldering iron. There is no point in pressing it on the printed circuit board in the hope of quickly melting the solder contact. We have to wait until the temperature at the soldering site will reach the required temperature. Otherwise, the soldering iron tip may slip off the board and accidentally touch your fingers or palm with the hot metal. Believe me, burn wounds take a very long time to heal!
You should also keep your eyes away from the soldering area. It is not uncommon that when overheated, the printed track on the board peels off with characteristic swelling, which leads to the spraying of tiny droplets of molten solder. If you have safety glasses, you should use them. Once you have gained sufficient soldering experience, you can dispense with safety glasses.
It is advisable to carry out soldering in a well-ventilated area. Lead and rosin fumes are harmful to health. If it is not possible to ventilate the room, then you should take breaks between work.
