How to solder SMD components - a brief instruction with photos. How to solder SMD components with a simple soldering iron How to solder smd components with a conventional soldering iron

When working with SMD components, radio amateurs are bound to face the problem of soldering them. Once faced with the need to solder more than a thousand components (which stretched out for three weeks), I sat down, scratched my turnips and came up with the following technology. I want to say right away that the technology is only suitable for soldering boards on which SMD components are located on one side. If there are such components on both sides, the second side will have to be soldered by hand.

1. You need to purchase solder paste. I got my hands on this one. Perhaps there are other varieties in nature. I took her. The paste is solder powder mixed with zinc chloride and some water-based viscous rubbish.

2. First, on a piece of paper on which a printed circuit board drawing is displayed (preferably in full size and indicating all the details), we lay out in their places all the SMD components that need to be soldered. There is no need to skip this step - when the next step is completed, you will have very little time to install the components on the board, so everything should be at hand in advance.

3. The etched printed circuit board is sanded and coated with solder paste with a brush. Pay special attention - drill holes in the board it is forbidden, they will need to be drilled only after soldering! The paste should barely cover the tracks so that they all "shine through" through the paste layer. To more evenly spread the paste over the board, it does not hurt to drop one drop of water on the board. Excess water is extremely harmful - when it boils away (see below), parts can move. Large empty spaces on the board, of course, do not need to be smeared with paste. It is better to pick up the paste from the bottom of the container, since the solder settles down, and viscous rubbish is mainly located in the upper part. Minimal mechanical effort should be used when picking so that the solder powder does not stick together under pressure (I usually just turn the jar over and give the paste time to drain down). In the instructions for the use of the paste, it is recommended to work in a respirator and in ventilated rooms. In my opinion, these recommendations are very worth following.

4. On the board prepared in this way, we shift all the components from the paper in their places. There is no need to try to install the components with particular precision, the main thing is that the component leads get to their contact pads. Large parts with a flat surface (for example, powerful keys) need to be pressed lightly during installation, the rest of the parts do not require any clamps.

6. We put four unnecessary SMD resistors on the surface of the iron, and on them - a board with laid out parts (resistors are needed to prevent contact between the board and the surface of the iron). We are patiently waiting. When the paste on the surface begins to melt (see the picture for the moment of miracle), wait for it to melt over the entire surface of the board, then carefully remove the board and let it cool. Do not try to touch or press something at the same time (especially large parts with a flat surface) - the solder will immediately flow out from under them and something will definitely close - checked! If a minimum of paste is smeared, no extraneous circuits (including under SMD microcircuit cases) never occur, no matter how incredible it may seem.

We drill holes. Installing the usual components. Enjoy.

The soldering turns out very neat - almost like a factory one. The speed of soldering increases not just at times - by orders of magnitude. The main problem is getting used to the temperature of the iron and the thickness of the paste layer. I would also venture to suggest that in this way it is not worth soldering the input stages of amplifiers with high input impedance - the remaining paste will surely burn into the surface layer of the board and ruin everything. Of course, instead of an iron, a soldering station with a hairdryer would be much better, but, alas ...

PS. More than a year and a half of experience with this technology has revealed several problems - and, of course, several ways to solve them. I will briefly list them:

• soldering single-sided boards in the described way is undesirable. The reason is simple - the coefficient of thermal expansion of copper and fiberglass is somewhat different from each other (albeit slightly). For this reason, when soldering, the bend of the board can reach 0.2..0.3 mm, because of which it heats up unevenly, and its edges burn slightly. In addition, for some brands of one-sided fiberglass, with such heating, internal delamination (formation of bubbles) begins. The solution is simple - always use double-sided fiberglass, and simply remove the unused side of copper. On double-sided fiberglass, the phenomena described above have never been observed, and soldering with it turns out to be much more "smooth" (apparently due to the fact that copper on the bottom side of the board ensures uniform heat distribution over the board surface).
• soldering can cause problems in high voltage circuits. The fact is that when soldering, flux and tiny tin balls inevitably remain on the surface of the board. At voltages up to 50..100 V, the dielectric properties of the board practically do not deteriorate, but at higher voltages, a "sparkler" begins on the surface, with inevitably sad consequences for the structure. To eliminate this trouble, you should follow some rules:
  • never strip the board before soldering. The skin will inevitably leave traces on the adhesive base, with which copper was glued to the fiberglass, and both tin and flux will surely settle on these grooves. Instead of stripping the board with sandpaper, it must be wiped with an acid solution (acetic, hydrochloric) before soldering, and then rinsed. Nitric and sulfuric acids should not be used, as the former leaves serious marks on the copper, while the latter destroys the board's backing.
  • I repeat the recommendation - a minimum of pasta. It practically shouldn't exist. The ideal case is when, after soldering, all the tracks of the board shine, but not a single drop of solder is noticeable on any of them.
  • if the board will work in high-voltage circuits, after washing it, preferably five minutes boil in the water (this is not a stupid joke, but an absolutely serious recommendation). It is advisable to add a few drops of vinegar to the water. After boiling, the board should be rinsed again and then dried in heat.
  • the board must be coated with zapon varnish or ISOTEMP varnish.

Installation and soldering of SMD elements at home - in our time, the assembly of electronic devices on SMD components, designed for installation on the surface of the board, is becoming increasingly popular. This installation technology is due to the most dense arrangement of parts, and in terms of economics it is technologically cheap production. On the Internet you can find many articles on the methods of mounting such electronic components, but each radio amateur has his own ways of working with SMD parts, so in my article I want to share my skills in surface mounting electronic parts with both beginner radio amateurs and those godfathers have not yet had a chance to work with SMD.

Attention! All images are clickable.

Necessary tools and materials

A little about the tools and materials that will be required in the process. There must be good tweezers, a needle (you can use a syringe), to apply the flux you will need a syringe with a thick needle, wire cutters, low-melting solder, and since the parts themselves are miniature and it is difficult to work with them with the naked eye, so you will also need a magnifying glass. And ideally, it would not be bad to have a device such as a head magnifier, for example, of this brand: MG81001-3LED is a magnifying glass with a set of three-dimensional lenses and built-in LED backlight. And you should also have a liquid flux, for example F-3 or self-prepared from pure rosin powder and alcohol, but it is still recommended to use commercially produced fluxes, their choice is huge on sale.

In domestic conditions, it is most preferable to solder SMD parts with hot air; for this, there are special soldering stations, and an electric dryer is installed instead of a conventional soldering iron. Such equipment is now on sale in large quantities, and if it is made in China, then the prices are low. Here, the photo shows such a Chinese device, the name is difficult to pronounce, but this station has been operating for about three years and so far has been trouble-free.

Naturally, you will not need a large soldering iron with a thin tip, where without it? The advantage here is given to a set of soldering tips "Microwave", manufactured according to the technology of the German company Ersa with 80 years of experience. The kit contains a tip of various shapes and purposes, the most common design is a tip with an internal recess, in which a metered amount of solder accumulates and is convenient when working with densely packed parts, and the likelihood of sticking between closely spaced microcircuit pins is also reduced. Be sure to purchase a set of replacement soldering tips that will make soldering much easier for you. In cases where you have not yet acquired such tips, then you can also solder with an ordinary thin conical tip.

On factory conveyors, the installation of SMD parts is carried out by applying a special paste to the board, then with the help of robots the components are placed in their mounting places, thereby sticking to the solder paste and sent to a thermal furnace along the conveyor. The boards are heated to a predetermined temperature in the furnace. During the heating process, the flux from the solder paste evaporates, and the solder melts to form a reliable contact connection between the part and the printed circuit board.

Based on factory technologies, you can try to reproduce these works in a home workshop. I think it will not be difficult to buy solder paste now, since it is available in electronics stores and on radio markets in a wide range. To apply the paste on the board in a metered amount, you need to use a thin needle from a syringe. I think the most suitable option would be to use the syringe itself, into which the paste is drawn, and then squeezed out onto the contact pads of the board. The photo shows how not to do it, that is, too much paste is squeezed out, especially on the left side of the board.

Nevertheless, we continue to work on installing components. We place parts on the pads with applied paste, at the moment these are capacitors and resistors. At this stage of the layout, tweezers are indispensable, and the tweezers should preferably be with curved ends, for example, it is more convenient for me to use this.

For a one-time installation of parts, you can of course do without tweezers, say, take a toothpick, and grease its tip with some kind of sticky substance, you can use the same flux, then it is quite possible to install the component on the site. It's just who how to adapt.

After completing the layout of the parts and placing them in their intended places, the process of heating with hot air begins. Low-melting solder begins to melt at a temperature of +178°С, and the temperature of hot air must be set by the regulator on the soldering station within +250°С, then, placing the tip of the hot air gun at a distance of about 100 mm, begin to carefully heat the board while gradually bringing the hot air nozzle closer to pay. You need to be more careful with the pressure of the hot air flow, in cases of its strong pressure, there is a high probability of blowing off all the parts from the board. As in industrial production, in a heating furnace, the flux evaporates when heated, and the solder changes its color as it melts, and gradually turns from dark to light and shiny. The picture below shows exactly the moment of its melting.

After the solder is melted, the hot air gun nozzle should be slowly removed from the surface of the printed circuit board, thereby allowing it to cool. The photo shows what ended up happening. Studies have shown that large drops of solder at the ends of the parts indicate that there is too much paste in these places, and where there is little solder, it means there was not enough paste.

It may happen that solder paste is not available in your region or it is too expensive for you, that is, a soldering option without using paste. This method will be shown in the photo, and a microcircuit will serve as an example. First, you need to cover all the sites where the components will be installed with a thick layer of solder, that is, apply tinning.

The pictures should show that the contact pads are covered with solder so that they form a kind of tubercle. Here, one of the important conditions is the uniform application of solder to all sites, that is, the height of the tubercles should be the same. After you have tinned, we drip a little flux from the syringe to the installation sites of the elements and wait a bit until it thickens. In this state, it will be easier for SMD parts to stick to the flux. With special care, using tweezers, we install the microcircuit in the place allotted for it. To combine the pins of the microcircuit with the pads on the board, this is already a matter of principle.

Near the microcircuit, I placed a number of passive elements, ceramic and polar capacitors. In order to avoid parts falling out from the board under the influence of a hot air jet from a hair dryer, we begin to heat the board as already mentioned above, with the hair dryer nozzle slightly removed from the surface of the parts. The main thing is not to rush with warming up, not an accurate movement of the air stream and small parts will all scatter.

Here's a look at what happened as a result of these actions. The picture shows that the containers are soldered, as it should be, but several legs of the microcircuit, marked in red, were not soldered. This marriage can be caused by several reasons, such as not enough solder on the pads or not enough flux was applied. This is corrected with an ordinary soldering iron with a thin conical tip. You need to add a little flux to the pad again and solder with the addition of solder. To prevent such defects, you should always use a magnifying glass.

For those radio amateurs who do not have a soldering station, you can get by, as mentioned above, with a simple soldering iron. Below, the pictures show examples of soldering resistors and two microcircuits using a soldering iron. The first example will be a resistor. We install a resistor on pre-prepared contact pads, that is, already with solder and flux applied to them. To avoid its shift during soldering, it must be pressed with an awl or needle.

Next, a short touch with the tip of the soldering iron on the output of the part on the site is enough and the component will immediately be soldered. Try not to pick up solder with a soldering iron tip, otherwise due to excess solder leakage may occur relative to adjacent leads or tracks.

Here is the result of soldering the resistor

The quality certainly leaves much to be desired, but it is reliable. The decrease in soldering quality is due to the inconvenience of simultaneously soldering, pressing the resistor and taking a photo, that is, the problem is the lack of a “third hand”.

The remaining electronic components are soldered in a similar way. As for me, at first I solder the base of a powerful transistor to the contact pad, while I do not save solder. Parts of the solder must flow under the body of the semiconductor, which will create an additional reliable electrical and thermal contact.

So that there is no doubt about the reliability of the soldering, then when you start to solder the part, move the transistor case with a needle, it should slide a little, this proves that the solder under the case has completely melted, and the excess is squeezed out, thereby improving thermal contact. The picture shows an already soldered stabilizer chip.

After soldering one leg, you need to once again check the accuracy of the installation of the microcircuit and the coincidence of its legs with the pads, and then we solder the rest of the leads along the edges.

Now the chip is securely fixed on four sides. Being careful, we solder the remaining legs, while making sure not to make jumpers with solder between the pins of the microcircuit.

At this stage of work, the tip for the “microwave” soldering iron will help a lot, it was mentioned at the beginning of the article. Using this tip, you can easily solder microcircuit assemblies with a large number of pins, in a fairly easy way, just run the soldering iron tip along the legs of the microcircuit. Jumpers between pins are very rare, and it takes about a minute to solder a chip with more than fifty pins on one side. This is such an amazing sting. Well, if you don’t have it, then do the work with a simple conical tip, but very carefully.

If there was such an unpleasant moment as soldering several pins of the microcircuit together, it is always problematic to remove these jumpers with only one soldering iron.

Then you can remove them using a piece of braid taken from a shielded wire. The braid must be placed in a container with flux so that it is saturated, and then applied to the problem area with an influx of solder and a soldering iron to heat the solder through this braid.

All excess solder will be absorbed into the braid, and the pad and the gap between the pins of the microcircuit will remain clean and free from unnecessary sticking.

At the end of the article, it remains to be hoped that this post was at least a little useful to you. And the quality of the photographs did not irritate you, since the photos were taken simultaneously with soldering. Good luck with your electronic business!

SMD components are small electronic components that are mounted on the surface of a printed circuit board. "SMD" (in transcription "SMD") is an abbreviation of the phrase from the English language "Surface Mounted Device", which translates as "a device mounted on a surface."

Another meaning of the word "surface" is that soldering is not done in the traditional way, when the leads of the components are inserted into the hole of the printed circuit board and soldered to the conductive tracks on the reverse side. SMD components are mounted on the front side, where all the tracks are located. This type of fit is called surface mounting.

SMD components, thanks to the latest technology, have a small size and weight. Any small element that functionally contains tens or even hundreds of resistors, capacitors and transistors will be several times smaller than an ordinary semiconductor diode.

As a result, radio-electronic devices made from surface-mounted components are very compact and lightweight.

The small size of SMD components does not create conditions for the occurrence of induced currents in the elements themselves. For this case, they are too small and do not affect performance. As a result, devices assembled on such parts work better, without creating interference and not reacting to interference from other devices.

SMD components can be placed very close to each other on the board. Modern parts are so small that most of the space began to be occupied by conductive paths, and not by radio components. This prompted manufacturers to make circuit boards multi-layered. They are like a sandwich of several boards, only the contacts from all the tracks are brought to the surface of the topmost of them. These contacts are called mounting patches. Such multilayer boards are very compact. They are used in the manufacture of mobile phones, smartphones, tablet computers. The details on them are so small that they can often be seen only under a microscope.

Soldering technology

As mentioned above, the soldering of SMD components is carried out directly on the surface of the mounting patches. Very often, the conclusions of the parts after installation are not even visible. Therefore, the use of a traditional soldering iron is not possible.

Soldering SMD components is carried out in one of several ways:

• heating the entire board in the oven;
• using an infrared soldering iron;
• using a hot air soldering iron or hair dryer.

When devices using SMD components are manufactured by industrial methods, special automatic robots are used. In this case, solder has already been pre-applied on the mounting patches in an amount sufficient for mounting. In other cases, during preparation, solder paste for SMD components is applied over the stencil. The robot arm puts the parts in place and securely fixes them. After that, the boards with installed SMD components are sent to the oven.

The temperature in the furnace is gradually increased to a certain value, at which the solder is melted. For the material from which boards and radio components are made, this temperature is not dangerous. After all the solder is melted, the temperature is lowered. The decrease is carried out smoothly according to a certain program determined by the thermal profile. It is with this cooling, and not with sudden cooling, that the soldering will be the most durable.

Board preparation at home

To solder SMD components with high quality in a home workshop, you will need an infrared soldering iron or a hot air station. Before soldering, be sure to prepare the board. To do this, it must be cleaned and irradiated patches. If the board is new and has never been used anywhere, you can clean it with an ordinary eraser. After that, it is necessary to degrease the surface by applying flux. If it is old, and there is dirt and remnants of the old solder on it, you can prepare it with fine-grained sandpaper, also degreasing after cleaning with flux.

Soldering SMD components with a conventional soldering iron is not very convenient due to the small size of the pads. But if there is no soldering station, then you can also use a soldering iron with a thin tip, working with it carefully, picking up solder on a heated tip and quickly touching the contact.

Paste application

To solder microcircuits with high quality, it is better to use not solder, but solder paste. To do this, the element must be placed on the board and fixed. Of the tools, tweezers, plastic clamps, small clamps are used. When the leads of the SMD component are exactly on the mounting patches, solder paste is applied to them. To do this, you can use a toothpick, a thin brush or a medical syringe.

You can apply the composition without worrying that it covers the surface of the board around the mounting patches. During heating, surface tension forces will collect it into drops and localize it at the places of future contacts of the SMD component with the tracks.

warming up

After application, heat up the installation area with an infrared soldering iron or a hair dryer (temperature approx. 250 °C). The soldering composition should melt and spread over the contacts of the mounted component and the patch. The power of the blow dryer must be adjusted so that it does not blow away drops of solder paste from the board. If the characteristics of the device used for soldering allow, the temperature should be reduced gradually. It is not allowed to accelerate cooling by blowing air over the contacts of SMD components.

The same technology is used for soldering LEDs, in case of replacing burned-out elements in any lamp or, for example, in instrument lighting. The only difference is that during soldering, the board must be heated from the side opposite to the one on which the components are installed.

Types of solder pastes

Solder paste is the best tool for automated soldering of SMD components. It is a viscous low-flowing flux substance, in which the smallest particles of solder are contained in suspension.

To be able to use it successfully, the paste must meet certain requirements:

• should not oxidize and exfoliate into components;
• must have a certain viscosity, that is, be liquid enough to melt from heating, and at the same time thick enough not to spread over the entire board;
• should not leave dirt and slag at the place of soldering;
• the paste should be well washed with common solvents.

According to the method of use, the compositions are divided into washable and non-washable. As the name implies, the remaining cleaning paste must be removed from the soldering area after completion, otherwise the components included in it can attack the traces and leads of the parts. No-clean compounds can remain after soldering, as they are completely neutral to the materials of boards and SMD components.

Washing agents, in turn, can be water-soluble and halogen-containing. Water soluble cleaners can be washed off the boards with deionized water.

Washing pastes sometimes contain halogens. They are introduced into the composition to improve performance properties. Halogen-containing pastes can be used for high speed printing or, conversely, where a very long setting time is required. Soldering properties are also improved by the introduction of halogens. Halogen-containing pastes are washed off with solvents.

DIY soldering paste

There are many brands and types of solder pastes on the market that meet all the conditions and requirements necessary for high-quality installation.

At home, you can make such a composition, having a hard solder bar, solder fat and flux on hand.

Solder must be crushed into a very fine fraction. This can be done with a file or sandpaper. The resulting dust from the tin-lead rod must be collected in a small container and mechanically mixed with soldering fat. If soldering fat is not at hand, you can use any liquid flux, and use ordinary petroleum jelly as a binder and thickener.

The consistency of the paste can be determined by eye, roughly calculating the proportions. The finished composition can be kept in a small plastic container with a tight-fitting lid. It is even better to load it into a regular medical syringe with a thick needle.

If you squeeze out the paste in a dosed manner at the place of future soldering, it will be very convenient to use such a paste, and the result will be durable and reliable.

Soldering smd parts without a hair dryer

Everyone understands how it is possible, with the help of a conventional soldering iron EPSN, with a power of 40 watts, and a multimeter, to independently repair various electronic equipment, with output parts. But such details are now found, mainly only in power supplies of various equipment, and similar power boards, where significant currents flow and high voltage is present, and all control boards now go to the SMD element base.

So what if we do not know how to dismantle and solder back SMD radio components, because then at least 70% of the possible repairs of equipment, we will not be able to perform on our own ... Someone who is not very deeply familiar with the topic of installation and dismantling will probably say , this requires a soldering station and a soldering dryer, various nozzles and tips for them, no-clean flux, such as RMA-223, and the like, which usually does not happen in a home master's workshop.

I have at home available, a soldering station and a hair dryer, nozzles and tips, fluxes, and solder with flux of various diameters. But what if you suddenly need to fix the equipment, on the road to order, or visiting friends? But is it inconvenient to disassemble and bring a defective board home, or to a workshop where appropriate soldering equipment is available, for one reason or another? It turns out there is a way out, and quite simple. What do we need for this?

What is needed for soldering?

1. Soldering iron EPSN 25 watts, with a tip sharpened into a needle, for mounting a new microcircuit.

2. Soldering iron EPSN 40-65 watts with a tip sharpened under a sharp cone, for dismantling a microcircuit, using Rose or Wood alloy. A soldering iron with a power of 40-65 watts must be turned on necessarily through a Dimmer, a device for adjusting the power of the soldering iron. It is possible such as in the photo below, very convenient.

3. Alloy Rose or Wood. We bite off a piece of solder with side cutters from a droplet, and put it directly on the contacts of the microcircuit on both sides, if we have it, for example, in the Soic-8 package.

4. Dismantling braid. It is required in order to remove solder residues from the contacts on the board, as well as on the microcircuit itself, after dismantling.

5. SCF flux (alcohol rosin flux, crushed into powder, dissolved in 97% alcohol, rosin), or RMA-223, or similar fluxes, preferably based on rosin.

6. Flux Off, or 646 thinner, and a small, medium bristle brush, usually used in school, for painting in art classes.

7. Tubular solder with flux, with a diameter of 0.5 mm, (preferably, but not necessarily this diameter).

8. Tweezers, preferably curved, L-shaped.

Unsoldering planar parts

So, how does the process itself take place? We bite off small pieces of solder (alloy) to Rose or Wood. We apply our flux, abundantly, to all contacts of the microcircuit. We put a drop of solder to Rose, on both sides of the microcircuit, where the contacts are located. We turn on the soldering iron, and set it with a dimmer, the power is approximately 30-35 watts, I don’t recommend it anymore, there is a risk of overheating the microcircuit during dismantling. We carry out the sting of a heated soldering iron, along all the legs of the microcircuit, on both sides.

Dismantling with Rose alloy.

At the same time, the contacts of the microcircuit will close with us, but this is not scary, after we dismantle the microcircuit, we can easily remove excess solder from the contacts on the board and from the contacts on the microcircuit with the help of a dismantling braid.

So, we took up our chip with tweezers, along the edges, where there are no legs. Usually the length of the microcircuit, where we hold it with tweezers, allows you to simultaneously drive the soldering iron tip, between the tips of the tweezers, alternately from both sides of the microcircuit, where the contacts are located, and slightly pull it up with tweezers. Due to the fact that during the melting of the Rose or Wood alloy, which have a very low melting point (about 100 degrees), relative to the lead-free solder, and even the usual POS-61, and moving with the solder on the contacts, it thereby reduces the overall melting point of the solder .

Dismantling microcircuits with a braid.

And in this way, the microcircuit is dismantled with us, without overheating dangerous for it. On the board, we have solder residues, Rose alloy and lead-free, in the form of sticky contacts. To bring the board back to normal, we take a dismantling braid, if the flux is liquid, you can even dip its tip into it, and put it on the solder “snot” formed on the board. Then we warm up from above, pressing down with a soldering iron tip, and draw a braid along the contacts.

Soldering radio components with a braid.

Thus, all the solder from the contacts is absorbed into the braid, passes to it, and the contacts on the board are completely cleaned of solder. Then the same procedure must be done with all the contacts of the microcircuit if we are going to solder the microcircuit to another board, or to the same one, for example, after flashing with a programmer, if it is a Flash memory chip containing the BIOS firmware of the motherboard, or monitor, or which or other technology. This procedure must be performed to clean the contacts of the microcircuit from excess solder.

After that, we apply the flux again, put the microcircuit on the board, position it so that the contacts on the board strictly correspond to the contacts of the microcircuit, and there is still some space left on the contacts on the board, along the edges of the legs. Why are we leaving this place? So that you can lightly touch the contacts, with a soldering iron tip, solder them to the board. Then we take a 25 watt EPSN soldering iron, or a similar low-power one, and touch the two legs of the microcircuit located diagonally.

Soldering SMD radio components with a soldering iron.

As a result, the microcircuit turns out to be “stuck” with us, and will no longer budge, since the melted solder on the contact pads will hold the microcircuit. Then we take solder with a diameter of 0.5 mm, with a flux inside, bring it to each contact of the microcircuit, and simultaneously touch the tip of the soldering iron, solder, and each contact of the microcircuit.

I do not recommend using solder of a larger diameter, there is a risk of hanging “snot”. Thus, we have solder “deposited” on each contact. We repeat this procedure with all contacts, and the microcircuit is soldered into place. With experience, all these procedures can really be completed in 15-20 minutes, or even in less time.

We only need to wash off the flux residues from the board, using solvent 646, or Flux Off cleaning agent, and the board is ready for tests after drying, and this happens very quickly, since the substances used for washing are very volatile. 646 solvent, in particular, is based on acetone. The inscriptions, silk-screen printing on the board, and the solder mask are not washed off or dissolved.

The only thing is that it will be problematic to dismantle a microcircuit in a Soic-16 package and more multi-output in this way, due to the difficulties with simultaneous heating, a large number of legs. Good soldering everyone, and less overheated microcircuits! Especially for Radio circuits - AKV.

How to solder SMD? Sooner or later, all electronics engineers had to deal with such a question.

There are times when a simple soldering iron cannot get close to SMD elements. In this case, it is best to use a soldering iron and thin metal tweezers.

In this article, we will talk about how to properly solder and desolder SMD. We will train on the corpse of the phone. I showed with a red rectangle that we will solder and solder back.

AOYUE INT 768 Soldering Station takes over

The hair dryer needs the right attachment. We choose the smallest one, since it will be a small smd-shku to solder and solder.

And here is the whole assembly.

Using a toothpick, apply the fluxplus to the smd-shku.

This is how we smeared it.

We set the temperature of the hair dryer at the soldering station to 300-330 degrees and begin to fry our part. If the solder does not melt, it can be thinned with Wood's or Rose's alloy using a thin soldering iron tip. As we will see that the solder begins to melt, with the help of a picent, we carefully remove the part without hitting the smd-shki that are nearby.

And here is our detail under the microscope

Now solder it back. To do this, we clean the patches (if you have not forgotten, these are contact pads) using a copper braid.

After we cleaned them of excess solder, we need to make bumps with new solder. To do this, we take quite a bit of solder on the tip of the soldering iron tip.

And we make tubercles on each contact pad.

Put the smd-detail there

And we warm it with a hairdryer until the solder spreads along the walls of the part. Do not forget about the flux, but you need very little of it.

Ready!

In conclusion, I would like to add that this procedure requires the ability to work with small details. Everything will not work right away, but whoever needs it will eventually learn how to solder and desolder SMD components. Some craftsmen solder smd-shki with solder paste. The solder paste I used when soldering the BGA chips in this article.