How to solder chips with a soldering iron. Easy circuits for beginners Soldering easy circuits for beginners
Recently, having learned that I am a radio amateur, two people turned to me for help on the forum of our city, in the Radio branch. Both for different reasons, and both of different ages, already adults, as it turned out during the meeting, one was 45 years old, the other 27. Which proves that you can start studying electronics at any age. They were united by one thing, both were somehow familiar with technology, and would like to master the radio business on their own, but did not know where to start. We continued our conversation in In contact with, to my answer that there is a sea of \u200b\u200binformation on this topic on the Internet, do it - I don’t want to, I heard from both about the same - that both do not know where to start. One of the first questions was: what is included in the required minimum knowledge of a radio amateur. It took quite a long time to list the necessary skills for them, and I decided to write a review on this topic. I think it will be useful for beginners like my friends, for everyone who cannot decide where to start their training.
I must say right away that when learning, you need to evenly combine theory with practice. No matter how much you want to quickly start soldering and assembling specific devices, you need to remember that without the necessary theoretical base in your head, at best, you can accurately copy other people's devices. Whereas if you know the theory, at least in a minimal amount, you can change the scheme and fit it to your needs. There is such a phrase, I think known to every radio amateur: "There is nothing more practical than a good theory."
First of all, you need to learn how to read circuit diagrams. Without the ability to read circuits, it is impossible to assemble even the simplest electronic device. Also, subsequently, it will not be superfluous to master the independent drawing up of circuit diagrams, in a special one.
Soldering parts
It is necessary to be able to identify by appearance, any radio component, and know how it is indicated on the diagram. Of course, in order to assemble, solder any circuit, you need to have a soldering iron, preferably not higher than 25 watts, and be able to use it well. All semiconductor parts do not like overheating, if you are soldering, for example, a transistor to a board, and you could not solder the output in 5 - 7 seconds, interrupt for 10 seconds, or solder another part at this time, otherwise there is a high probability of burning the radio component from overheating.
It is also important to solder carefully, especially closely located leads of radio components, and not to hang “snot”, accidental short circuits. Always, if in doubt, ring a suspicious place with a multimeter in sound dialing mode.
It is equally important to remove flux residue from the board, especially if you are soldering digital circuits, or with flux containing active additives. Rinse off with a special liquid, or 97% ethyl alcohol.
Beginners often assemble circuits by surface mounting, right on the pins of the parts. I agree that if the conclusions are securely twisted together, and then soldered, such a device will last a long time. But in this way it is no longer worth assembling devices containing more than 5 - 8 parts. In this case, you need to assemble the device on a printed circuit board. The device assembled on the board is highly reliable, the connection diagram can be easily traced along the tracks, and, if necessary, all connections can be called with a multimeter.
The downside of printed wiring is the difficulty of changing the scheme of the finished device. Therefore, before wiring and etching the PCB, you always first need to assemble the device on a breadboard. It is possible to make devices on printed circuit boards in different ways, the main thing here is to observe one important rule: copper foil tracks on textolite should not have contact with other tracks, where this is not provided for by the scheme.
In general, there are different ways to make a printed circuit board, for example, by separating sections of the foil - tracks, a groove cut through a cutter in the foil made from a hacksaw blade. Or by applying a protective pattern that protects the foil under it, (future tracks) from etching with a permanent marker.
Or with the help of LUT technology (laser - ironing technology), where the tracks are protected from etching by the burnt toner. In any case, no matter how we make a printed circuit board, we need to first route it in the tracer program. I recommend for beginners, this is a manual tracer with great features.
Also, when wiring printed circuit boards yourself, or if you printed a finished board, you need the ability to work with the documentation for the radio component, with the so-called Datasheets ( Datasheet), pages in PDF format. There are datasheets on the Internet for almost all imported radio components, with the exception of some Chinese ones.
On domestic radio components, you can find information in scanned directories, specialized sites that host pages with the characteristics of radio components, and information pages of various online stores such as Chip & Dip. It is necessary to be able to determine the pinout of the radio component, the name pinout is also found, because very many, even two-output parts have polarity. It also requires practical skills in working with a multimeter.
A multimeter is a universal device, with the help of only one, you can carry out diagnostics, determine the conclusions of the part, their performance, the presence or absence of a short circuit on the board. I think it’s not superfluous to remind, especially to young novice radio amateurs, the observance of electrical safety measures when debugging the operation of the device.
After assembling the device, you need to arrange it in a beautiful case so that you are not ashamed to show it to your friends, which means that you need locksmith skills if the case is made of metal or plastic, or carpentry if the case is made of wood. Sooner or later, any radio amateur comes to the conclusion that he has to deal with minor repairs of equipment, first his own, and then with the acquisition of experience, and from friends. And this means that it is necessary to be able to diagnose a malfunction, determine the cause of the breakdown, and then eliminate it.
Often even experienced radio amateurs, without tools, find it difficult to desolder multi-pin parts from the board. It’s good if the parts are being replaced, then we bite off the leads near the case itself, and solder the legs one at a time. It is worse and more difficult when this part is needed to assemble some other device, or a repair is being made, and the part may need to be soldered back after, for example, when looking for a short circuit on the board. In this case, tools for dismantling are needed, and the ability to use them is a braid and a desoldering pump.
I don’t mention the use of a soldering iron, due to the frequent lack of access for beginners to it.
Conclusion
All of the above is only part of the necessary minimum that a novice radio amateur should know when designing devices, but with these skills, you can already assemble, with a little experience, almost any device. Specially for the site AKV.
Discuss the article HOW TO START FOR A RADIO AMATEUR
Who shared interesting ideas on this topic in the comments. It is clear that two skills are needed for the goals set, one of which is the installation of a printed circuit board. So today we will solder, from scratch.
Another set was taken from the shelf of the children's store, specifically this one.
So, we are testing the "Set of Young Electronics Engineer". Will it be possible with its help to assemble working structures from scratch without prior skills, as we did before with a mechanical model?
The kit already has everything to quickly complete the assembly:
- soldering iron, solder with a flux channel (very handy!) and wire cutters
- multimeter
- two printed circuit boards with details
The set also includes two brochures:
1. A manual that contains general information about devices, parts and the soldering process.
2. Instructions for assembling two devices included in the set and subsequent configuration of one of them.
The brochures are good, but, if you remember, I liked the instructions for the robot more, where there were no words - only images + step-by-step assembly. There are no step-by-step instructions in the instructions for this set. In some ways, this is good, because if you focus on these two brochures, whether you like it or not, you will first have to read and understand everything, and only then act - that is, they teach you to think systematically. But there is a little lack of dynamics, and it seems to me that the children may also miss this even more than I do. Therefore, if you collect something similar, I hope this post will save you a lot of time.
Additional Tools
What is not in the kit, but you will need or may need:1. Tweezers. We took a manicure.
2. Battery "Krona" for 9V
3. Phillips screwdriver - one of the diagrams has a terminal. Tighten the wires in it with a clock Phillips screwdriver.
4. Device for soldering "third hand" - that's really what you can do without, although it is constantly mentioned in the instructions and brochure. Of course, it would be more convenient with it, but if you just assemble all the parts on the board and then turn it over, then both boards included in the set will be relatively stable and it will be convenient to solder, in principle, without additional devices.
5. Magnifier
6. Desoldering pump
7. Glasses and respirator
8. Stand for soldering iron
9. Fan \ extractor
Of this entire list, it will be very difficult only without the first two points. This time, the robot from the previous post became the stand for the soldering iron. The rest for mounting two small boards would be really superfluous.
But it would be useful to recall that when soldering, tin vapors are released, which are not very good for health. Actually soldering the two circuits included in the kit took me no more than 10 minutes and I didn’t get sick. However, a small fan to push the smoke aside, or at least an open window, is standard and very good practice. Also, wash your hands after soldering. You also need to take care of your eyes - the part’s leg bitten off by wire cutters can fly off or a drop of hot tin can fly off during the soldering process (although it didn’t fly off with us). So wear safety goggles. Take care of yourself!
Nutrition
To begin with, all we need is a separately purchased Krona battery. The kit has a connector for it, which, according to the instructions, must be soldered into the first circuit. My advice: don't do it, leave it as it is and use it in both circuits - both for testing the first one and for setting up the second one.
The devices that we will assemble consume some insane amount of mA / h.
If we are talking about an electrical circuit, then our resources and how we quickly spend them are measured in A \ h (Amps per hour, mAh). The capacity of a typical "Krona" (according to the passport):
625 mAh ≈ 0.5 Ah
The first device, "Chameleon", consumes up to 200 mAh. Therefore, our Krona this scheme is enough for:
625mAh/200mA = 3.125 hours.
mAh is how fast the battery will run out! =)
It would be cool to be able to solder one of these connectors onto the boards, and then include such a laboratory power supply in it. But there are no suitable holes for any of the available connectors on the board. Therefore, we cannot yet connect the power supply.
The first pancake is lumpy or immediately troubleshooting
There is such an anecdote: a man bought an airplane and a magazine with the description "How to make a dead loop." Following the instructions, I got on the plane, took off, began to make a dead loop - everything works out. He turns the page, and there: "... read the way out of the dead loop in the next issue."
You can talk a lot about the culture of soldering and that it is a whole art. One thing will remain unchanged: if you do something for the first time and according to the book, then at first it may not work out. Here is our first board, the Chameleon set, or rather what came out of it. What mistakes were made?
1. The soldering technology is broken, as a result - unsoldered contacts, which are better to be soldered and soldered again (without reversing the polarity!)
2. The technology of work is violated: each part was soldered in turn. Below you will see how much more profitable it is to listen to the instructions in this regard and first assemble all the details, and then fix them.
Result: the details stand beautifully in a crooked and slanted way, and out of the three chains of diodes, only one caught fire in the end.
Possible Solution: unsolder all parts and solder again.
Solder!
So, the first circuit did not work out for us due to a violation of the soldering technology, so we will immediately discuss this simple and actually pleasant moment.The brochure clearly shows and tells how to solder, but, unfortunately, it didn’t help me much, because it says “how to”, but I would like to understand the technique itself.
It's all in the process. You need to do it like this:
- The part is inserted into the board and must be secured (you will not have a second hand to hold).
- A soldering iron is taken in one hand, a wire of solder is taken in the other (it is convenient if it is in a special dispenser, as in the picture).
- Solder on the soldering iron is NOT NECESSARY.
- Touch the tip of the soldering iron to the place of soldering and heat it. Usually, it's 3-4 seconds. (actually 1-2 s. - approx. A.Ch.)
- Then, without removing the soldering iron, with the other hand, touch the tip of the solder wire with the flux to the place of soldering. In reality, in this place all three parts come into contact at once: the soldering element and its hole on the board, the soldering iron and the solder. After a second, “pshshshshsh” occurs, the tip of the solder wire melts (and a little flux flows out of it) and the required amount of flux goes to the place of soldering. After a second, you can remove the soldering iron with solder and blow.
Additionally, I can recommend an illustrated comic, translated by habruser atarity.
Also, from time to time, carbon deposits form on the tip of the soldering iron and need to be cleaned. To do this, the industry uses special cellulose sponges, necessarily moistened with water. In our case, carbon deposits can be removed simply by shaking it off mechanically - for example, with the blunt side of a knife.
Step-by-step instruction
After the first device was unfairly ruined by us, there was an understanding of how to build the process more efficiently. I hope this step-by-step guide will help you build your own kit just as quickly.
So, we have a handful of details and we have no idea what's what. We take a nice manicure tweezers (which was at home) and select all the resistors from this pile.
This is how they look. If you look closely, we will see that we have 8 identical, 2 more identical and 1 “by itself”. You need to look closely at the striped markings on the case. On the board, the place for the resistor is indicated by R (resistor). The first 8 identical ones are placed in a row at the bottom, as can be seen on the board, 2 more identical ones are at the top left and one, which is “by itself” - in fact, is mounted “by itself”.
Good news: Resistors have no polarity. This means that it does not matter to us which side we put them on the board. Therefore, without thinking for a long time, we give the desired shape to the contacts, put everyone on the board, cut off the excess with wire cutters. To make it easier to solder, we put the board on the edge of a small cardboard box, because if it was placed on a table, it would not make it possible to solder the resistors a little above the board, as is recommended.
Here's what we'll get. Still far from ideal, but already much better than the first set! We continue.
Now let's select all the capacitors. On the board, the places for them are designated C (capacitor). Capacitors are either polar or non-polar. This means that some capacitors, if they are put on the board on the “wrong side”, will not work and the whole circuit will not work. Hint: the yellow capacitors are non-polar, so just put them in sockets C3 and C4.
Cylindrical capacitors are polar. How to determine polarity? Two ways:
1. Before trimming the legs, the one that is longer is a plus. It is enough to combine it with the “+” marking in the seat of the capacitor C1 or C2
2. The blue stripe on the capacitor is the "key". She is where the minus is. It is enough to place it on the reverse side of the "plus" marking.
Clue: if you are too lazy to think, just put polar capacitors as in the image.
And diodes! Diodes are all polar. Ways to determine polarity:
1. Longer leg is a plus.
2. Chamfer (bevel) on the side of the base of the diode itself. Not very convenient, because with transparent diodes it is almost completely invisible. All the chamfers of the diodes on this board should be on one side - the outer one.
3. Put the multimeter in ringing mode (the "wi-fi" icon, but in fact - a sound signal, on the multimeter), with the black wire (minus) touch the short leg, the red (plus) - long. In our case, the diode will light up. If you reverse the polarity, it won't light up. This is because the diode only allows current to flow in one direction.
If you reverse the polarity of at least one diode, then the entire chain will not burn. But! These three methods for determining the polarity of the diode did not disappoint us. The latter method can be used again after installation to ring the circuit and make sure that the polarity of the diodes is not reversed.
We only have a few more details left. Clockwise in photo:
Button. Not polar. Just put and press lightly - it will be fixed on the board.
Microcircuits: they have "keys" on top of the case. The one that is longer has a notch that must be combined with the designation on the board. In our case, the notch will look to the right, towards the resistors. The chip has a smaller key in the form of a recess in the upper left corner. There he should be on the diagram. Also, this recess is schematically indicated on the board, also from above.
Pay attention to the good old "tube" (in the sense - cozy) DIP microcircuits. Now, apart from kits for creativity, you can hardly find them anywhere, although soldering them for me personally is a pleasure, as well as assembling gear mechanisms. In industry, the traditional methods used by our parents and grandparents of those to whom this set is intended have been replaced by surface mounting.
Chip voltage stabilizer. With her, everything is simple, it will not work to confuse anything.
Terminal connector. Here we will connect the power supply. Therefore, it is important: at the terminal connector, the holes for the wire should look outward from the board, otherwise they will be covered by a closely standing capacitor, and it will become difficult to rivet the wires in the terminal (in fact, this is what happened with us). In case of incorrect placement of the terminal connector, it will most likely not be possible to desolder it without a vacuum desoldering pump (we did not succeed).
Ready! We managed to make only one significant mistake during assembly - this is the location of the terminal connector. But this does not affect the polarity, rather, the ease of use.
We got a mini-checking device that will always show how much battery is left. Now we will set it up to check the Kron battery, which we already have and in which the charge is 9V, until it runs out.
We connect a new, not yet dead battery. We observe the polarity (the positive terminal connector is marked on the board). The first red LED lights up. The scheme works!
Briefly press the button once. The device measures the voltage at 9V and stores it. If we had a shrunken Krona nearby, we could check the charge difference.
Clue: You can quickly defuse Krona using the first scheme, if you, of course, assembled it correctly. As we have already said, it consumes up to 200 mA, so it will drain the battery in about three hours.
Actually, the multimeter included in the kit also copes with the same functions of measuring voltage, but it does this, of course, not so effectively. If you have a laboratory power supply, you can reprogram our device every time for a new voltage. The same can be done by connecting different batteries and pressing the "remember" button again.
In conclusion, I want to say thanks to those who came up with and created this set. Two days ago, I had no idea about the PCB assembly process. Now I distinguish a resistor from a transistor and I can put them on the board using keys, a multimeter and other clues. In addition, I managed to immediately assemble one of the devices and put it into operation! As always, it is very pleasant to see and hold in your hands what you managed to assemble on your own.
Thanks to this two-day immersion in electronics, it became clear to me what else I want to know:
1. How to call the assembled circuit board to find where the defect is and fix it, rather than resoldering the whole board (I still have hope to rebuild the first device!).
2. How to calculate the power consumption of the circuit and independently calculate how long one or another battery charge will last?
3. Three indicators that we measured during the assembly process with a multimeter - the number of volts in the battery, the resistance in ohms of the resistor, the current measurement in amperes. How are they related and what can I do about it?
4. How to read the circuit diagram of the device and see it on the board? How to combine paragraph 3 and paragraph 4?
And also, tell me, please, what would you do with the power supply of devices, terminals and connectors, because so far I have only the option “two protruding wires and a Kron battery”. Add tags
Modern electronic devices cannot be imagined without microchips - complex parts, which, in fact, integrate dozens, if not hundreds of simple, elementary components.
Microcircuits allow devices to be made light and compact. You have to pay for this by the convenience and ease of installation and the rather high price of parts. The price of a microchip does not play an important role in shaping the overall price of the product in which it is used. If you spoil such a part during installation, when replacing it with a new one, the cost can increase significantly. It is easy to solder a thick wire, a large resistor or a capacitor, for this it is enough to have basic soldering skills. The microcircuit must be soldered in a completely different way.
To avoid unfortunate misunderstandings, when soldering microcircuits, it is necessary to use certain tools and follow some rules based on numerous experience and knowledge.
For soldering microcircuits, you can use various soldering equipment, ranging from the simplest - a soldering iron, to complex devices and soldering stations using infrared radiation.
A soldering iron for soldering microcircuits should be low-power, preferably designed for a supply voltage of 12 V. The tip of such a soldering iron should be sharply sharpened to a cone and well tinned.
To solder microcircuits, a vacuum desoldering pump can be used - a tool that allows you to alternately clean the legs on the board from solder. This tool is like a syringe in which the piston is spring-loaded upwards. Before starting work, it is pressed into the body and fixed, and when necessary, it is released by pressing a button and rises under the action of a spring, collecting solder from the contact.
More advanced equipment is considered to be a hot air station, which allows both the dismantling of microcircuits and hot air soldering. Such a station has in its arsenal a hair dryer with an adjustable temperature of the air flow.
When soldering microcircuits, such an element of equipment as a heating table is very in demand. It heats the board from below, while mounting or dismantling operations are performed from above. Optionally, the thermostatic table can be equipped with top heating.
On an industrial scale, soldering microcircuits is carried out by special machines using infrared radiation. In this case, the circuit is preheated, directly soldering and smooth stepwise cooling of the legs contacts.
At home
Soldering chips at home may be required to repair complex household appliances, computer motherboards.
As a rule, to solder the legs of the microcircuit, a soldering iron or a blow dryer is used.
Work with a soldering iron is carried out using ordinary solder or solder paste.
Recently, lead-free solder with a higher melting point has become more common. This is necessary to reduce the harmful effects of lead on the body.
What fixtures will be required
For soldering microcircuits, in addition to the soldering equipment itself, some more devices will be required.
If the microcircuit is new and made in a BGA package, then the solder is already applied to the legs in the form of small balls. Hence the name - Ball Grid Array, which means an array of balls. These cases are designed for surface mounting. This means that the part is mounted on the board, and each leg is soldered to the contact patches with a quick, precise action.
If the microcircuit has already been used in another device and is used as used spare parts, it is necessary to perform reballing. Reballing is the process of restoring solder balls on legs. Sometimes it is also used in the case of a blade - loss of contact between the legs and contact patches.
To carry out reballing, you will need a stencil - a plate of refractory material with holes located in accordance with the location of the pins of the microcircuit. There are ready-made universal stencils for several of the most common types of microcircuits.
Solder paste and flux
For proper soldering of microcircuits, certain conditions must be observed. If the work is carried out with a soldering iron, then its tip must be well tinned.
To do this, a flux is used - a substance that dissolves the oxide film and protects the tip from oxidation before coating with solder during the soldering of the microcircuit.
The most common flux is pine rosin in a solid, crystalline form. But to solder a microcircuit, such a flux is not suitable. Its legs and contact patches are treated with liquid flux. You can make it yourself by dissolving rosin in alcohol or acid, or you can buy it ready-made.
Solder in this case is more convenient to use in the form of a filler wire. Sometimes it may contain flux from powdered rosin inside. You can purchase a ready-made soldering kit for soldering microcircuits, which includes rosin, liquid flux with a brush, and several types of solder.
When reballing, solder paste is used, which is a base of viscous material, which contains the smallest balls of solder and flux. Such a paste is applied in a thin layer on the legs of the microcircuit on the reverse side of the stencil. After that, the paste is heated with a hairdryer or an infrared soldering iron until the solder and rosin are melted. After solidification, they form balls on the legs of the microcircuit.
Work procedure
Before starting work, it is necessary to prepare all the tools, materials and fixtures so that they are at hand.
When mounting or dismantling, the board can be placed on the heating table. If a soldering gun is used for dismantling, then in order to exclude its effect on other components, they must be isolated. This can be done by installing plates of refractory material, for example, strips cut from old boards that have become unusable.
When using a desoldering pump for dismantling, the process is more accurate, but takes longer. The desoldering pump is "charged" by cleaning each leg. As it fills with pieces of solidified solder, it must be cleaned.
There are several soldering rules that must be followed:
- it is necessary to solder the microcircuits on the board quickly so as not to overheat the sensitive part;
- you can hold each leg with tweezers during soldering to provide additional heat removal from the case;
- when mounting with a hair dryer or an infrared soldering iron, it is necessary to monitor the temperature of the part so that it does not rise above 240-280 ° C.
Electronic parts are very sensitive to static electricity. Therefore, when assembling, it is better to use an antistatic mat that is placed under the board.
Why dry chips
Chips are microcircuits enclosed in BGA packages. The name, apparently, came from an abbreviation that meant "Numerical Integrated Processor".
According to the experience of using professionals, there is a strong opinion that during storage, transportation, shipment, the chips absorb moisture and during soldering, it, increasing in volume, destroys the part.
The effect of moisture on the chip can be seen if the latter is heated. Blisters and bubbles will form on its surface long before the temperature rises to a value sufficient to melt the solder. One can only imagine what happens inside the part.
To avoid the undesirable consequences of the presence of moisture in the chip package, the chips are dried before soldering during board assembly. This procedure helps remove moisture from the case.
Drying rules
Drying of chips must be carried out, observing the temperature regime and duration. New chips that were purchased from the store, from the warehouse, sent by mail, it is recommended to dry for at least 24 hours at a temperature of 125 ° C. For this, special drying ovens can be used. You can dry the chip by placing it on a heating table.
The drying temperature must be controlled to prevent overheating and failure of the part.
If the chips were dried and stored before installation under normal room conditions, it is enough to dry them for 8-10 hours.
Given the cost of the parts, it's obviously better to dry them out so you can start mounting with confidence than trying to solder a chip that isn't dry. Troubles can turn into not only a waste of money, but also lost time.
Most electronic devices these days run on microchips. Therefore, sooner or later, every home master is faced with soldering microcircuits. At first glance, the process does not present any difficulty: pick up a soldering iron and attach the elements to the board. But here you need to understand that there is a huge difference between soldering a large resistor and a cell phone chip.
The hot air soldering station has an adjustable heating range, which minimizes the risk of overheating the soldered components.
Each specific case requires the method that will be most effective. If in the first case an ordinary electric soldering iron with a power of no more than 40 W, solder and hard rosin is suitable, then for soldering BGA microcircuits you cannot do without a no-clean flux, a hot air station, solder paste and stencils. The board heating station will not be superfluous.
The minimum set of tools for work
Before proceeding with the connection of complex elements, a novice home craftsman should familiarize himself with the basics of conventional soldering. As a rule, it is made using the simplest electric soldering iron with a copper tip called a sting.
In addition, for any soldering, a minimum set of materials is required:
- Solder. An alloy of tin and lead, characterized by high fusible properties and used to fasten elements to the motherboard or to each other. In the recent past, pure tin was used for solder, but today such a material is unreasonably expensive. In addition, the strength characteristics of an alloy of lead with tin are in no way inferior to pure metal. In specialized shopping centers, you can purchase different types of solder that have standard or improved properties.
- Flux. The use of fluxes facilitates the soldering process and prevents oxidation of the metal of the soldered elements. Today, the most popular material used as a flux is refined tree resin - rosin. In stores you can find special formulations designed for soldering specific metals. So, when soldering nickel, stainless steels and aluminum, a substance made from rosin and acid can be used.
Work can only be started when all soldering tools are assembled.
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Basic rules for contact soldering
The main rule of high-quality soldering is to ensure that the surfaces are clean. Even new items purchased from the store can be covered with various contaminants and oxides. Thus, if a dark gray or green oxide is found on the metal, it must be removed with sandpaper or a penknife. Uncleaned contaminants will interfere with soldering, and then the quality operation of the device.
The second rule is the need for tinning. Tinning is the coating of the surfaces to be welded with an even and thin layer of solder. Usually new elements for microcircuits are sold in stores already with tinned contacts and leads, but if this is not the case, this action must be performed independently.
To ensure the quality of the connection, the contacts of the elements must be tinned before soldering.
At home, the contacts of the elements and wires are tinned using an electric soldering iron. First of all, it is necessary to clean the surface of oxides, then apply rosin to it. The operation algorithm is simple: the contact or output of the element is applied to a piece of rosin and heated with a soldering iron tip, on which a little solder is applied. Next, the molten solder is neatly distributed over the entire surface to be treated. When the heating temperature reaches the desired level, the rosin will begin to evaporate. An even and smooth coating is formed on the surface of the element, without spools or lumps.
The third rule is to work only with a well-heated soldering iron. In working condition, the soldering iron tip must have a temperature of at least 180 ° C. Since the simplest tools do not have a heating scale, you can judge their readiness by boiling rosin when you touch it with a sting. If the substance does not melt, but spreads slowly, the tool is not yet ready. Working with an underheated tool will lead to soldering, which looks like a dark rough slurry.
To carry out the quality of soldering, it is necessary to remember the fourth rule: a soldered contact, made in accordance with all the rules of soldering, must have a shiny and even surface with a characteristic metallic sheen. To achieve this, it is necessary to take into account the dimensions of the processed surfaces. So, the larger the soldering area, the more heat transfer the work will require, that is, the power of the soldering iron depends entirely on the soldering area. For dense printed circuit boards or small-sized radio elements, tools with a power of 25 to 40 W are used, in other cases, more powerful devices should be used.
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Conditions for soldering
When soldering parts of the motherboard, several important conditions must be observed:
- monitor the operating time and do not overheat the board and metal tracks above 240-280 ° C (this is a critical temperature, the excess of which can lead to delamination or deformation of the board at the place of heating);
- make a rigid fixation of the processed elements: any slight vibration or displacement will violate the quality of soldering;
- carry out work in a well-ventilated area, since rosin and lead vapors adversely affect the respiratory system;
- work carefully and slowly, protecting your eyes and hands from burns as much as possible.
Subject to all the above rules, soldering work will not lead to damage to the treated surfaces and will not require rework.
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Chip soldering algorithm
The complexity of working with microcircuits lies in the too close arrangement of elements, which makes the installation process difficult.
If special equipment for soldering microcircuits is available, this will greatly simplify the task, but if necessary, the work can be done with a simple soldering iron with an awl-shaped tip.
The correct location of the chip: the key (circled in red) should be located near the beveled corner of the square.
All work can be divided into 2 phases. The first phase involves tinning (applying rosin and solder to the elements), and the second - installing the elements in the right places on the board. In order for the work to be done with high quality, it is necessary, in addition to the above tools and materials, to prepare 1 or 2 tweezers, preferably with clamps.
When the soldering iron is hot enough, you can get to work. First of all, it is recommended to tin the patches on the board where the necessary elements will be installed. The work is done as follows:
- on the patches of the board where the elements will be installed, a little flux is dripped;
- then solder is applied to the soldering iron tip;
- with light precise touches, the alloy is transferred to the patches.
Then the elements are installed. The element must be taken with tweezers and attached to the place of soldering. When working with microcircuits, the element should be held by the leg that will be processed. While one hand holds the tweezers with the part, with the other hand you need to apply a drop of rosin to the leg of the element and the place of soldering. Then the soldering iron tip should touch the surfaces to be treated. Since the board has already been pre-tinned, the element leg will sink into the molten solder. Thus, the procedure is repeated for all legs of the element.
When all the elements are installed in the right places, it is advisable to lubricate with flux and slightly smooth the contacts between them located on the surface of the motherboard with a heated soldering iron.
For the convenience of carrying out the work, you can use not lumpy rosin, but a special liquid flux, which is sold in hardware stores. Also, experts recommend purchasing additional equipment that will facilitate the soldering of microcircuits:
- liquid for washing boards (when using a liquid flux, there is a high probability that the solution will get on the surface of the board, which may adversely affect its operation);
- suction, which removes excess solder (the alloy is heated by a soldering iron and drawn into the device);
- goggles (to avoid injury to the eyes during work).
It is worth soldering the microcircuits once or twice - and this work will not cause any difficulties. The main thing is not to rush and do everything with the maximum degree of accuracy and attentiveness.