How to solder smd components. Quick desoldering of SMD components with an iron

Many people wonder how to solder SMD components correctly. But before dealing with this problem, it is necessary to clarify what these elements are. Surface Mounted Devices - translated from English, this expression means surface mount components. Their main advantage is a greater mounting density than conventional parts. This aspect affects the use of SMD elements in the mass production of printed circuit boards, as well as their cost-effectiveness and manufacturability of installation. Conventional parts with wire-type leads have fallen out of favor along with the rapidly growing popularity of SMD components.

Errors and the basic principle of soldering

Some craftsmen claim that soldering such elements with their own hands is very difficult and rather inconvenient. In fact, similar work with HP components is much more difficult to carry out. In general, these two types of parts are used in various areas of electronics. However, many people make certain mistakes when soldering SMD components at home.

SMD components

The main problem that amateurs face is the choice of a thin tip for a soldering iron. This is due to the existence of the opinion that when soldering with an ordinary soldering iron, you can smear the legs of SMD contacts with tin. As a result, the soldering process is long and painful. Such a judgment cannot be considered correct, since the capillary effect, surface tension, and wetting force play an important role in these processes. Ignoring these additional tricks makes it difficult to do the job yourself.

Soldering SMD components

In order to properly solder SMD components, certain steps must be followed. To begin with, apply the soldering iron tip to the legs of the element taken. As a result, the temperature begins to rise and the tin melts, which eventually completely flows around the leg of this component. This process is called wetting force. At the same instant, the tin flows under the leg, which is explained by the capillary effect. Together with wetting the legs, a similar action occurs on the board itself. The result is a uniformly filled bundle of boards with legs.

Solder contact with neighboring legs does not occur due to the fact that a tension force begins to act, forming individual tin drops. It is obvious that the described processes proceed on their own, with only a small participation of the solderer, who only warms up the legs of the part with a soldering iron. When working with very small elements, they may stick to the tip of the soldering iron. To prevent this from happening, both sides are soldered separately.

Soldering in the factory

This process takes place on the basis of the group method. Soldering SMD components is carried out using a special solder paste, which is evenly distributed in a thin layer on the prepared printed circuit board, where there are already contact pads. This method of application is called screen printing. The material used in its appearance and consistency resembles toothpaste. This powder consists of solder to which flux has been added and mixed. The application process is carried out automatically as the printed circuit board passes through the conveyor.

Factory soldering of SMD parts

Further, the robots installed along the movement tape lay out all the necessary elements in the right order. Parts in the process of moving the board are firmly held in place due to the sufficient stickiness of the solder paste. The next step is heating the structure in a special furnace to a temperature that is slightly higher than that at which the solder melts. As a result of this heating, the solder melts and flows around the legs of the components, and the flux evaporates. This process makes the parts soldered into place. After the stove, the board is allowed to cool, and everything is ready.

Necessary materials and tools

In order to do the soldering of SMD components with your own hands, you will need certain tools and consumables, which include the following:

• soldering iron for soldering SMD contacts;
• tweezers and side cutters;
• an awl or needle with a sharp end;
• solder;
• a magnifying glass or magnifying glass, which are necessary when working with very small details;
• neutral liquid flux no-clean type;
• a syringe with which you can apply the flux;
• in the absence of the latter material, an alcohol solution of rosin can be dispensed with;
• for the convenience of soldering, the masters use a special soldering dryer.

Tweezers for installing and removing SMD components

The use of flux is essential and must be liquid. In this state, this material degreases the working surface, and also removes the oxides formed on the soldered metal. As a result, an optimal wetting force appears on the solder, and the soldering drop retains its shape better, which facilitates the entire process and eliminates the formation of "snot". The use of an alcohol solution of rosin will not allow you to achieve a significant result, and the resulting white coating is unlikely to be removed.

The choice of soldering iron is very important. The best tool is one that can be adjusted in temperature. This allows you not to worry about the possibility of damage to parts by overheating, but this nuance does not apply to the moments when you need to desolder SMD components. Any soldered part is able to withstand temperatures of about 250-300 ° C, which provides an adjustable soldering iron. In the absence of such a device, you can use a similar tool with a power of 20 to 30 W, designed for a voltage of 12-36 V.

Using a 220 V soldering iron will not lead to the best results. This is due to the high heating temperature of its tip, under the influence of which the liquid flux quickly evaporates and does not allow the parts to be effectively wetted with solder.

Experts do not advise using a soldering iron with a conical tip, since the solder is difficult to apply to parts and a lot of time is wasted. The most effective is considered a sting called "Microwave". Its obvious advantage is a small hole in the cut for a more convenient grip of the solder in the right amount. Even with such a sting on a soldering iron, it is convenient to collect excess soldering.

You can use any solder, but it is better to use a thin wire, with which it is comfortable to dose the amount of material used. The soldered part with the help of such a wire will be better processed due to more convenient access to it.

How to solder SMD components?

Work order

The process of soldering, with a careful approach to theory and gaining some experience, is not difficult. So, the whole procedure can be divided into several points:

1. It is necessary to place SMD components on special pads located on the board.
2. A liquid flux is applied to the legs of the part and the component is heated with a soldering iron tip.
3. Under the action of temperature, the contact pads and the legs of the part are flooded.
4. After pouring, the soldering iron is removed and time is given for the component to cool. When the solder has cooled, the job is done.

The process of soldering SMD components

When performing similar actions with a microcircuit, the soldering process is slightly different from the above. The technology will look like this:

1. The feet of the SMD components fit exactly into their contact points.
2. In places of contact pads, wetting with flux is performed.
3. To accurately hit the part on the seat, you must first solder one of its extreme legs, after which the component is easily exposed.
4. Further soldering is carried out with the utmost care, and the solder is applied to all legs. Excess solder is removed with a soldering iron tip.

How to solder with a hair dryer?

With this method of soldering, it is necessary to lubricate the seats with a special paste. Then the necessary part is placed on the contact pad - in addition to components, these can be resistors, transistors, capacitors, etc. For convenience, you can use tweezers. After that, the part is heated with hot air supplied from a hair dryer at a temperature of about 250º C. As in the previous soldering examples, the flux evaporates under the action of temperature and melts the solder, thereby flooding the contact tracks and legs of the parts. Then the hair dryer is removed, and the board begins to cool. When completely cooled, the soldering can be considered finished.

Increasingly, SMD parts are used in production, as well as among radio amateurs. It is more convenient to work with them, since it is not necessary to drill holes for the leads, and the devices are very miniature.
SMD components are quite reusable and reusable. Here again, the obvious superiority of surface mounting appears, because it is much easier to solder small parts. They are very easy to blow off with a special soldering dryer from the board. But if you don’t have this at hand, then an ordinary household iron will help you out.

Dismantling of SMD parts

So, my LED lamp burned out, and I will not fix it. I will unsolder it into parts for my future homemade products.

We disassemble the light bulb, remove the top cap.

We take out the board from the base of the base.

We solder hinged components and parts, wires. In general, there should be a board with only SMD parts.

We fix the iron upside down. This must be done firmly so that it does not tip over during the soldering process.
The use of an iron is also good because it has a regulator that will quite accurately maintain the set temperature of the sole surface. This is a huge plus, since surface components are very afraid of overheating.
We set the temperature to about 180 degrees Celsius. This is the second ironing mode, if my memory serves me right. If soldering does not work, gradually increase the temperature.
We put the board from the light bulb on the sole of the inverted iron.

We wait 15-20 seconds until the board warms up. At this time, we wet each detail with flux. The flux will not overheat, it will be a kind of assistant when desoldering. With it, all elements are removed without difficulty.

Once everything is well warmed up, all the parts can be brushed off the board by hitting the board on some surface. But I'll do it carefully. To do this, take a wooden stick to hold the board in place and use tweezers to disconnect each component of the board.
Naked board at the end of work:

Soldered details:

I had a lot of questions about dismantling microcircuits in various buildings. I suggest you familiarize yourself with the most common options. soldering chips in dip and smd packages.

First of all, we should talk about dismantling of microcircuits a process that is the most accessible to radio amateurs, but also somewhat complicated compared to that which will be described a little later.

A method for dismantling microcircuits in a dip - case using a soldering iron and a few items that can be found in the house.

You need a soldering iron and a needle from a ten-cc syringe. Cut off the point of the needle so that it is even, without a point. We insert the needle with a hollow hole into the leg of the microcircuit from the bottom side, slowly heating it until the needle passes through the hole in the board. Without removing the needle, let the surface and solder cool, remove the needle. We remove excess solder from the needle, repeat the process on the remaining pins of the microcircuit. With some skill, it turns out neatly and efficiently - the microcircuit itself falls out of the board without effort from the outside.

You will need a soldering iron and braided copper cable. We apply a layer of flux on the copper braid, put the legs of the microcircuit on one side and warm it up. When heated, the braid "pulls" the solder onto itself from the surface of the board on which the microcircuit is located. When the braid is saturated, the unnecessary part is simply cut off, and dismantling continues. I must say that this method is suitable for dismantling Dip - components, and for Smd - components.

All you need to work is the same soldering iron and something thin, such as tweezers or a watch screwdriver with a flat sting. Carefully slip the flat part of the screwdriver (or tweezers) between the microcircuit and payment to some reasonable depth, heat the legs from the back side, and slowly raise the side. We repeat the same process, but now on the other side of the part: we insert a screwdriver, heat the legs, lift it up. And we repeat this process until the chip is removed from the board. The method is very fast, simple and even rude. But we must not forget that the tracks on the board and the microcircuit itself have their own temperature limit. Otherwise, it is possible to be left without a working microcircuit, or with peeled tracks.

Soldering iron and solder suction are required. The solder suction is something like a syringe, but with a piston that works on the principle of suction. We heat the output of the microcircuit, immediately apply the suction for solder, press the button and the rarefaction created inside the suction “pumps out” the solder from the track. Unfortunately, everything looks so easy and simple only in words. In fact, when heating the leg, you need to almost instantly get on the leg with suction, and “pump out” the solder, which requires a high speed of execution, because the solder hardens almost instantly, and if you hold the soldering iron longer, there is a risk of getting peeled tracks or a burnt component again .

Now we will talk about the dismantling of components using a soldering gun. The method is the most simple, effective, fast and high-quality. But, unfortunately, a soldering gun is not a cheap tool.

The method of dismantling the microcircuit indip - case.

You need a soldering iron, tweezers, preferably non-magnetic. A flux is applied from the side of the legs, and heating starts from the same side. The condition of the tin on the terminals is visually controlled - when it has become sufficiently liquid, carefully grab the part from the side of the case with tweezers and pull it out of the board.

Dismantling the chip insmd execution.

The principle is the same - a flux is applied along the tracks, heated at a certain temperature, the degree of heating is determined by lightly pushing the part with tweezers. If the part has become movable, slowly and carefully remove it from the surface of the board with tweezers, holding it by the edges, and trying not to hook the tracks.

It is very important not to overheat the dismantled parts and the surface! Each microcircuit and part has its own temperature limit, overstepping which, the part or board will be damaged. The hair dryer must be held STRICTLY vertically, choosing the right nozzle, evenly heating the entire surface of the microcircuit. And do not forget to set the air flow such that you do not accidentally blow off neighboring components.

Well, here, perhaps, are all the available ways to dismantle microcircuits. I hope you got an answer to the question: how to solder a microcircuit.

There was a desire and a need to switch to more compact circuits than those assembled on a conventional breadboard. Before thoroughly purchasing textolite, elements and microcircuits for surface mounting, I decided to try and see if I could assemble such a trifle. In the vastness of Aliexpress, there was an excellent “simulator” for very reasonable money. If you have soldering experience, it makes little sense to read the review

The set is a light effect running lights, the speed is regulated by a variable resistor.
Everything arrived in a standard pimply envelope, in a zip package.

Appearance of the set

In addition to the kit, I used POS-61 solder, RMA-223 flux, tweezers, and a soldering iron.

Consumables

If there can be no special impressions on the solder, then I have something to say about the flux.
He seemed too fat to me, or something. In general, it is quite difficult to wash it with alcohol in the company of a toothbrush, and I am not entirely sure that there are no residues of it under the microcircuits. However, the flux is working and I have good impressions from soldering it, especially until I started cleaning the board))). I will add to the pluses that the flux is neutral and, unlike the same soldering acid, its minor residues are not capable of harming the components. So the flux is credited, and my complaints about cleaning are more subjective, before that I used the FCS water-washable flux and it seemed to me easier to handle.
In addition, any flux gel, compared to liquid, has a very convenient plus, after applying it, the part can be “sticked” to the board on the gel and aligned. Not so hot what a mount, but accidentally touching the board or tilting it is no longer scary. Next, we press the element with tweezers and solder. I tried several ways to solder loose smd (resistors, capacitors), the most convenient was to tin one contact pad, solder a number of elements on one side, and only then go through the second part. Moreover, the shape of the sting turned out to be not particularly important, almost any, even the thickest, will do.

soldering iron

I ended up using these healthy stings ... It turned out to be very convenient for them to correct crooked elements, since its size is enough to heat both soldering points, and then I was too lazy to change it.

Microcircuits have a similar scheme, first we fix one leg, then we solder everything else, I didn’t like the hair dryer categorically, it often blows off components, it’s difficult for me to use it. Soldering microcircuits with a hairdryer - yes, soldering - no.
Larger elements, such as power legs (as on this board) or radiators, thick wires, I advise you to solder with soldering acid, it works wonders. If there is varnish on the wires (for example, audio, for the sake of interest, you can disassemble the old headphones and try to solder it), it is easiest to burn it with a torch-lighter, tin with acid and calmly solder. There is a more convenient way - to use an aspirin tablet as a flux, like rosin - the varnish is removed with a bang and the wire has a neater appearance. Here I did not use wires, I assembled it "as is".


Perhaps it will be more convenient for someone to solder not on the table, but to fix the board in the holders

Holders

the third hand, heat shrink is put on the crocodiles so as not to scratch the textolite, and the board at the same time keeps many times better


PCB Holder

For those who are interested, I added a video of the board in action. I tried to photograph the result and the name of the microcircuits as large as possible. By the way, everything worked the first time, for half a buck try your hand, fluxes, solders or upgrade your skill - that's it.

A couple more photos

This article will consider one of the working ways to unsolder smd components. At what the desoldering will take place in a not quite standard way, but despite this, it is very effective. The heating of the elements takes place evenly, without the danger of overheating, since the temperature can be regulated!

Increasingly, SMD parts are used in production, as well as among radio amateurs. It is more convenient to work with them, since it is not necessary to drill holes for the leads, and the devices are very miniature.

SMD components are quite reusable and reusable. Here again, the obvious superiority of surface mounting appears, because it is much easier to solder small parts. They are very easy to blow off with a special soldering dryer from the board. But if you don’t have this at hand, then an ordinary household iron will help you out.

Dismantling of SMD parts

So, my LED lamp burned out, and I will not fix it. I will unsolder it into parts for my future homemade products.

We disassemble the light bulb, remove the top cap.

We take out the board from the base of the base.

We solder hinged components and parts, wires. In general, there should be a board with only SMD parts.

We fix the iron upside down. This must be done firmly so that it does not tip over during the soldering process.

The use of an iron is also good because it has a regulator that will quite accurately maintain the set temperature of the sole surface. This is a huge plus, since surface components are very afraid of overheating.

We set the temperature to about 180 degrees Celsius. This is the second ironing mode, if my memory serves me right. If soldering does not work, gradually increase the temperature.
We put the board from the light bulb on the sole of the inverted iron.

We wait 15-20 seconds until the board warms up. At this time, we wet each detail with flux. The flux will not overheat, it will be a kind of assistant when desoldering. With it, all elements are removed without difficulty.

Once everything is well warmed up, all the parts can be brushed off the board by hitting the board on some surface. But I'll do it carefully. To do this, take a wooden stick to hold the board in place and use tweezers to disconnect each component of the board.
Naked board at the end of work:

Soldered details:

This method will allow you to solder any boards with SMD parts very quickly. Arm your friends!