How to solder SMD LEDs with a soldering iron

How to solder SMD LEDs correctly

I use some skills that I haven’t seen described anywhere, so I decided to share them ( at the end of the note - see the video of the process ). SMD housing - 0805.

It is impossible to make the sting not tremble

Not a single person is able to make sure that a tool (any tool - not just a soldering iron ) does not tremble in his hands. Once upon a time I read about masters who paint miniature paintings or murals. The technology they use in their work was described there. Its essence is that it is necessary to coordinate the movements of the hand with the beats of the heart. The inevitable actually occurs from heartbeats .

There is no need to fight trembling - it is useless. You need to learn to adapt to it.

Bird's beak technique

When a bird builds a nest, inserting another branch, it makes short and multiple movements with its beak. Even if it is necessary to correct a twig that has already been inserted into the nest, the bird performs each action by making several small and precise movements. In truth, these movements are not always accurate, but in total they still give the desired result.

The mistake of many beginners is that when soldering they try to make a long and continuous movement. It's useless. The secret is that you need to make short movements (ideally they are coordinated with the heartbeats, but you don’t need to specially concentrate on this - over time it should work out by itself).

Soldering an SMD element in three stages

The difficulty of soldering SMD elements with a conventional soldering iron is to hold the part with tweezers .

Those. At the very beginning of soldering, the main attention should be concentrated on the strength of the hand holding the tweezers. It is also important here to choose the correct viewing angle in order to clearly see how smoothly the part lies in its place.

It doesn't hurt to know one little secret.
At the very beginning, it is enough to just “ grab ” the part slightly. No need to try to solder it on the first side right away! Good soldering requires transferring attention to the soldering process itself - concentration on the tweezers is lost.

Thus, first we only grab the part from one end.
Having grabbed the part, we get rid of the tweezers and solder the second side of the part. And only then do we return to the final soldering of the first side.

Do not forget that the areas for the element on the board must be level . If there was solder there, you need to carefully remove the excess before soldering, otherwise the part will remain “skewed” after soldering.

So, when the part is stuck, it is no longer possible to move it (unless you overheat or apply noticeably great effort). This allows you to take a break from holding it, and concentrate on soldering from the other end , and then return to the first.
Thus, soldering occurs in three stages:

1. "Picking" of the part
2. Soldering the opposite end to the “stuck” end
3. Return to soldering the “stuck” end

Below is a video that I recorded when I was finalizing the video and audio output for the old FUNAI
(see the article FUNAI tvr 1400a mk7 - how to make a video output).

All the tools used are simple and crude, including a homemade brush made from fishing line (with which I wash the soldering area with alcohol ).
Rosin - ordinary, “pebble”. Soldering iron - 25 watts. BY THE WAY! The best soldering iron for “delicate” parts is one on which the rosin “smoke”, but does not have time to completely boil over on the tip for about 7 seconds. If the rosin boils away within 2-3 seconds, then the soldering iron tip is too hot and can damage the SMD element.

acceptable to be captured , even with some minor blemishes (touching an adjacent pad, dripping of excess rosin), which was facilitated by the camera, which required me to hold the tools almost at arm's length.
Nevertheless, this soldering is normal and the essence of the technique was demonstrated here. I recommend expanding the video to full screen and setting the quality in the video settings.

Source: https://MyTooling.ru/instrumenty/kak-pravilno-pajat-smd-svetodiody

DIY soldering of SMD components. Instructions

This article will cover a short guide on soldering SMD components . You will learn how to solder multi-legged microcircuits, as well as get acquainted with the main points and possible difficulties that may arise during the soldering process and learn how to avoid them. The article clearly shows how to solder SMD components with your own hands , and also talks about the necessary equipment and solders, I hope it will be useful!

 
Every day, radio amateurs are increasingly using SMD parts and components in their work. Despite their size, they are easier to work with: you don’t need to drill holes in the board, bite off long pins, etc. It is imperative to master soldering of SMD components, as it will definitely come in handy.

This master class is not intended for beginners in soldering, but rather for amateurs who are good at soldering but have a little difficulty soldering multi-legged microcircuits or controllers.

What you need to solder SMD components

It’s best to buy a ready-made kit for soldering SMD components , which contains all the necessary tools and accessories.

Buy SMD soldering kit

This is a minimal set, without expensive soldering stations, hair dryers and desoldering pumps.

We solder SMD components with our own hands

So, let's start with the most difficult thing - soldering the controller in the QFP100 case. With chip resistors and capacitors, I think everything is clear. The main rule here: there is no such thing as too much flux, or you won’t ruin the soldering with flux. Excessive application of flux prevents tin from spreading abundantly over the contacts and shorting them. There is also a second minor rule: even a little solder can be a lot. In general, you need to dose and apply it to the sting very carefully so as not to overdo it, otherwise it will flood everything at once.

Tinning the site

Experienced radio amateurs do not always perform this step, but in the first couples I recommend doing it.

You need to tin the board, namely the place where the controller will be soldered. Of course, the site is most likely tinned, especially if the board was made in production. But over time, an oxide film appears on the contacts, which can hinder you. Heat the soldering iron to operating temperature. Lubricate the area generously with flux. We apply a little solder to the tip and tin the tracks.

We remove excess solder using the PSH wire. It absorbs solder perfectly due to the capillarity effect.

Installing and aligning the controller

Once the site is prepared, it's time to install the controller. There is a trick here; most solders install the microcircuit and use tweezers to align its contacts along the tracks. But this is very difficult to do, since even a slight twitch of the hand throws the controller a considerable distance. It will be much easier to do this if you grease the corners diagonally with flux paste.

Now we install the controller and adjust it with tweezers.

As soon as the microcircuit is installed, we solder the contacts diagonally.

We check that all contacts are in the right place.

Soldering SMD contacts of the microcircuit

Here you can already use both liquid and viscous flux. We apply it very liberally to the contacts.

We wet the tip with a drop of solder and clean off the excess with a sponge.

And, carefully move along the lubricated contacts.

There is no need to rush in this matter.

Removing excess flux and solder

After soldering all the contacts, it's time to remove excess solder. Probably several contacts stuck together.

We wet the contacts very generously with liquid flux. We completely clean the soldering iron tip from solder with a sponge and go over the sticky contacts. Excess solder should be drawn onto the tip. To remove excess flux, use SBS - an alcohol-gasoline mixture mixed 1:1.

We wet it generously.

And we wipe everything thoroughly!

Watch the video with the master class:

Be sure to watch the video, where you can clearly see the movement of the soldering iron and all the manipulations.

Source: https://kavmaster.ru/pajka-smd-komponentov-svoimi-rukami-instrukciya/

How to solder LEDs correctly

Nowadays, the most common type of lighting is LED. Thanks to the huge number of advantages, such light sources have taken their place in almost any area of ​​human activity.

LEDs

Without them it is no longer possible to imagine electronic equipment, modern toys and many other attributes of modern society. LED strips are especially often used as lighting devices today. Therefore, it is very important to know how to solder diodes with your own hands in order to independently repair failed radio-electric parts at home or replace them correctly.

We remember the school physics course

In order to solder LEDs (for example, SMD type), you need to know what some of the signs on the circuits mean. Namely:

• "U". This letter on all electrical diagrams indicates voltage. It is measured in V (volts);
• "I". Under this designation lies the current. It is measured in A (amps);
• "R". This letter means the electrical resistance of the circuit elements. This indicator is measured in Ohms (ohms).

All of the above values ​​reflect Ohm's law, which is described by the following formula:

In addition, you need to understand that under the letter “P” is power, which is measured in W (watts). Power is determined by the following formula:

The decoding of these values ​​must be known in order to correctly solder LEDs into any circuits and boards.

How are diodes connected?

Before you start soldering LEDs (for example, SMD type), you need to know how they are connected to the circuit or in series to each other (if we are talking about LED strips).

Note! LEDs are most often connected to a network with a voltage of 12 or 9 V. But usually the devices are designed for a current consumption level of 0.02 A (20 mA).

Current stabilizer

The ideal option for LEDs is to connect them through a current stabilizer. It should be remembered that such stabilizers will cost slightly more than single LEDs (for example, SMD type). This must be taken into account when independently assembling radioelectric devices.

In order to power yellow and red LEDs, a voltage of 2.0 V is often required. At the same time, to power blue, green and white LEDs - 3.0 V. The
following example will help to understand this issue:

• a 12 V battery is available, as well as 0.02 A and 2.0 V LEDs;
• the simplest solution here would be to supply a voltage of 2.0 V to each diode;
• in this case, the extra 10 V will need to be extinguished using a resistor. It is also often called resistance;
• Using Ohm's law, we calculate the resistance value (R = U/I). As a result, we get R = 10.0/0.02 = 500 Ohm;
• Also, in order to protect the resistance from excess heat, it is necessary to calculate its power. The result will be P = 10.0 * 0.02 A = 0.2 W.

For greater reliability, it is necessary to take a resistance of slightly larger capacity.
Note!
As the resistance power increases, its overall dimensions will naturally increase. Knowing the above aspects, you will be able to connect the LEDs to the battery correctly using a resistor for this. The main thing here is to strictly observe the polarity of the parts used.

What is needed for work

Many radio electronics enthusiasts who practice self-assembly of various devices are interested in the possibility of independently soldering LEDs (for example, SMD type) for circuits.
If you have the proper tools and knowledge, creating such circuits yourself is quite possible. For this type of work you will need:

• tester;
• calculator;
• medical tweezers (optional, but recommended);
• soldering iron

Tester

Note! When working with LEDs, especially when testing them, you need to be careful not to direct the beam coming from these elements into your eyes.

As you can see, the set of tools here is small and can easily be found in any home. With this kit, you will be able to correctly solder diodes, both in the circuit and in series as part of the LED strip.

The structure of diode elements and how to solder them

A standard LED is a glass bulb with an approximate diameter of 5 mm, to which lead legs are attached.

Diode appearance

The short leg represents the negative terminal, and the long leg represents the positive terminal.
If you mix them up when soldering, the LED will not light up. The process of soldering such elements has the following algorithm:

• We place each diode in its own place;
• soldering areas should be treated with ordinary tin or flux;
• after that, apply a soldering iron to them for a couple of seconds;
• After this, the remaining legs can simply be bitten off.

After you have soldered all the LEDs to the circuit, you need to check your handiwork.
To do this, they must be connected to power. If all the diodes light up, this means that you did everything correctly. In addition, there are LEDs, which, for ease of working with them, are produced in the form of special strips. They can be cut and connected to each other, which makes it possible to use them for lighting rooms, shop windows, etc.

Places for cutting LED strips and soldering wires

Such tape should only be cut in appropriate places. If you cut in another place, you will simply ruin the product by damaging the LED connection. Such pieces need to be soldered using special contact pads that end these sections.

Note! You can solder LED strips using a soldering iron with a power of 40 V.

As a flux, you should use a special solution that looks like a gel. Remember that the ends of the wires in this situation should be well tinned. You can also use special devices to create contacts between pieces of LED strip - connectors. But they are quite expensive, so they are rarely used.

Soldering Features

After we have refreshed our school knowledge and the basics of connecting LED elements, and also found all the necessary tools, we can begin to directly work with the parts.
LEDs can be connected in series. The important thing here is to know how to do it correctly.

Note! In order to solder diodes in series, they should be selected with the same parameters.

The resulting chains of LEDs can be used in a wide variety of devices and purposes. Most often, they are used to organize various types of lighting (open or closed) for premises, as well as vehicles. When installing such chains, you should remember that the voltage in the car's electrical network will be higher than 12 V (14-14.5 V). The machine's power supply is not characterized by constant voltage. To suppress possible interference, special voltage stabilizers are needed.

Chip KREN8A

Independent assembly of voltage stabilizers is possible on the basis of KREN8A and K142EN8A microcircuits for a 9 V network. KREN8B and K142EN8B microcircuits are suitable for a 12 V network. A
small-sized soldering iron is suitable for soldering this element. Its tip should heat up to 260 degrees.

Note! The duration of the soldering process for each point should be 3-5 seconds.

To ensure that the soldering itself went correctly, you need to know the following rules and recommendations:

• If you don’t have even minimal soldering experience, you need to practice first. Otherwise, there is a high risk that the LEDs will not work or will even deteriorate. To improve your skills, you should use wires with different cross-sections;
• It is imperative to use standard tin-lead solder and flux for aluminum;

Flux for aluminum

• Wires that have not been covered with oxides must be tinned immediately after exposure. To do this, you need to take a small amount of solder and heat it on the soldering iron tip. Then we touch the rosin with it and run it along the exposed sections of the wires. As a result of such manipulations, the solder will spread into a thin film;
• sometimes tinning is not allowed. Then the wire should be placed on an aspirin tablet and heated with a soldering iron. Heating lasts 3-5 seconds.

LED soldering process

Knowing these rules, you can correctly solder the LEDs in series.

Another soldering option

In addition to conventional LEDs, there are chips that are mounted in LED strips. The most common LEDs today are SMD type.

SMD LED

This circuit element is a leadless component. SMD does not have traditional copper lead wires. Therefore, such elements are connected using printed circuit board tracks. Soldering is also used to connect the SMD diode to the board.

It is necessary to solder track tracks and contact pads to them.
Soldering such a circuit component is not difficult, since for this you can use a low-power type of soldering iron with a capacity of 10-12 W.

Therefore, you can quite conveniently and quickly solder each contact in series separately.

Soldering SMD components

There are situations when it is necessary to desolder SMD components to replace or test them. In such a situation, in order to prevent the element from overheating, you need to warm up all its terminals at the same time.

If such a need with SMD components happens often, then it makes sense to purchase a special set of soldering iron tips. These tips should have two or three small branched ends.

They are very easy to work with SMD as the risk of damage is minimized even when they are glued to the PCB.

Sometimes it is impossible to use a low-power soldering iron. Then, in order not to damage the element during soldering, a copper wire with a diameter of one millimeter should be wound to the tip of a powerful soldering iron.

Source: https://1posvetu.ru/montazh-i-nastrojka/kak-payat-svetodiody.html

How to solder LEDs: varieties, procedures and connection methods

Lamps have long been used as the main operating element of lighting systems. They have gone through many stages of structural and functional development, but today they are experiencing a crisis due to fierce competition with diode crystals. Modern LED lamps have become widespread due to their performance qualities, which, however, also have negative aspects of use.

In the process of repairing such a device, the user may encounter the problem of updating failed crystals. The question of how to solder an LED logically arises if one of the crystals has burned out. This will be indicated by the presence of a black dot on the yellow surface of the element.

And if, under the conditions of a factory layout, the restoration operation is carried out mechanically in an in-line mode, then at home it will be necessary to organize conditions for manual soldering.

What types of LEDs are there?

In most cases, ordinary users of lighting devices deal with output LEDs and a more advanced design based on SMD crystals. The first are introduced into the circuit using two conductors and most often serve as a means of indicating various equipment - for example, in a car they perform the tasks of a warning light, operating from a 12 V source.

Directly in lighting and illumination systems, SMD diodes in leadless packages are more often used. Due to the fundamentally different electrical layout on the board, this particular lighting device is more likely to cause complications.

How to solder SMD LEDs? Fastening is carried out not through special holes, as is the case with the same output devices, but directly to the surface with an overlay. For this purpose, special contact pads are provided, which must be soldered one by one, maintaining the correct placement of the diodes on the board.

On the one hand, this approach simplifies the technology of mounting crystals, but on the other hand, it requires more attention from the performer, since one has to deal with elements of miniature sizes, compactly placed in a small space.

As part of the preparatory process, several tasks must be resolved. of these consists of cleaning the working surface and, if necessary, dismantling the burnt-out diode. Old elements are best removed with low-power 25 W soldering irons after tinning the tip to the required size, which will allow for convenient thermal cutting. Next, special attention is paid to the surface.

Varnishes and all kinds of technical coatings must also be removed mechanically - for example, by cleaning them with a construction knife. Now another question - how to solder LEDs onto aluminum boards? In this case, it would be a good idea to prepare a special flux for a specific metal or use universal tin-lead solder. As for choosing a soldering iron, there will be no need for high power.

You can give preference to compact models with heating up to 250 °C.

Angle connection technique

Often, when creating complex lighting systems from several parallel lines, wires are connected in different areas. To make this connection easier, corner soldering with a 90-degree angle is used. Plus and minus are fixed on the contact pads of two adjacent diodes. What’s also important is that this method allows you to easily connect RGB strips using four wires.

The corner joint does not affect the quality of the backlight in any way, but allows you to implement a variety of configurations for splicing LED strips. Problems can only be caused by the presence of a special casing for tapes with a protection class higher than IP68. For example, how to properly solder LEDs filled with silicone or compound? In this case, the initial cleaning procedure becomes more complicated.

At a minimum, it will be necessary to form technical holes in the coating for current-carrying conductors. Soldering is then carried out using them.

Among the advantages of LED devices, one of the main places is their optimization, which is also reflected in the minimum requirements for consumables during installation. Nevertheless, sometimes the inclusion of connectors in electrical circuits justifies itself.

How to solder LEDs with such elements? Soldering in this case acts as an auxiliary means of ensuring a reliable connection between the wires, and the connectors form a kind of reinforcing internal frame. The optimal width of the connector is 8-10 mm.

At the first stage, it is necessary to create a structural connection by making the required number of contacts on the board, and then proceed directly to soldering.

It should be taken into account that a connection to a connector does not always provide an advantage from the point of view of future operation of the LED. Firstly, connection points with such fittings are more prone to burning, and also contribute to the rapid heating of the emitter.

Secondly, the glow may deteriorate, which is reflected in a decrease in brightness.

How to solder LEDs onto a board with a connector to eliminate such negative effects? It is advisable to abandon copper conductors and perform the soldering itself in a continuous manner, which will eliminate the risk of the formation of oxidation sites.

Overlap joining technique

A method that does not involve the use of auxiliary conductors at all. This technique is recommended for use with strip lights and other diode devices, the crystals of which are placed compactly on a small board.

For example, how to solder SMD LEDs with an overlap soldering iron? To begin with, the ends of the LED lines are cut so that the contacts are close to each other. The current-carrying conductors are lubricated with flux, after which tin plating can be applied until a silver coating is formed.

Then one piece with a wire part is overlapped onto another piece, strictly observing polarity. A short period of gentle heating is enough to form a strong connection.

Soldering procedure

Whatever connection method is chosen, the general soldering technology involves performing a universal set of actions, including the following:

• Solder or flux is used to tinning the current-carrying contacts that are planned to be connected.
• The ends of the current-carrying wires, which have already been tinning, are applied to the connection point on the board or other conductor.
• Now the main operation is connection. How to solder LEDs manually? It is enough to point the soldering iron tip at the target area of ​​the connection and hold it there for 3 to 5 seconds. As a result of rapid heating, a reliable joint is formed.
• After soldering, it is advisable to keep the docking unit isolated for several hours without any external influences.

Features of soldering with a hairdryer

Soldering using this method is usually considered as an alternative method to classical soldering. It is chosen for various reasons, the main one of which is the ability to remove heat from the crystal while minimizing the risk of thermal damage. But this method is only suitable for designs with a surface connection on the board.

For example, how to solder SMD LEDs with a hairdryer? The heating process is organized on the back side of the board. The performer's task is to ensure sufficient heating of the connection area so that the solder on the front side reaches a state that allows the diode to be securely fixed.

Theoretically, this action can be accomplished with an iron and a low-power gas burner, but to preserve the structure and the board itself, it is still safer to use a special heat gun.

Soldering errors

Even if the externally created connection seems correct, the device may not work correctly if technological errors were made. Most failures are associated with improper distribution of solder or melt, which results in typical defects such as lack of fusion.

How to solder LEDs to avoid this result? Both the solder and the melt must be strictly controlled during thermal exposure. The uniformity of the layers of the connecting coating must be maintained.

To identify such violations in the structure, scanning with a thermal imager is performed at the non-destructive testing stage.

Conclusion

Soldering LED lamp crystals is a simple operation that any home craftsman can do. However, there are a lot of technological subtleties and details, ignoring which can nullify even the efforts of a diligent craftsman. It is necessary to take into account not only the conditions for soldering as such, but also the connection configuration itself.

For example, how to solder SMD LEDs with a group arrangement of crystals? To successfully perform such an operation, at a basic level, you will need to determine the electrical circuit for installing diodes on the board.

It is necessary to calculate the circuit and only after that proceed to element-by-element connection of crystals in accordance with the planned configuration of the lighting device.

Source: https://FB.ru/article/469530/kak-payat-svetodiodyi-raznovidnosti-poryadok-deystviy-i-sposobyi-soedineniy

How to solder LEDs correctly: what is important to know, common mistakes

› Workshop

30.08.2019

Today, LEDs are recognized by ordinary users, radio amateurs and industrial enterprises as the most environmentally friendly, compact and energy-efficient light sources.

Low-power diodes are used to backlight monitors, mobile phones and in various toys, and high-power LEDs are used in workshop spotlights and festive luminescence of buildings, in the advertising business.

But the unusual light source has a number of maintenance features, in contrast to energy-saving analogues (ESL) and incandescent lamps. It is not so easy, for example, to solder LEDs. This article is devoted to this issue.

Structure of diode elements

The main difference from other lamps is that LEDs have a positive and negative contact (anode and cathode). When soldering a diode in a circuit, it is important to take this into account.

You also need to understand that there are DIP and SMD LEDs.

The positive contact in DIP is determined quite simply. It is worth taking a close look inside the flask. The positive terminal - the anode - is smaller than the negative one. In the picture, the plus is on the left.

There is a second way - look at the length of the leg. It is longer at the positive terminal.

The third way is with a multimeter. The black terminal of the device is negative, the red terminal is positive. Let's call:

The last method is suitable for both types.

This is perhaps the most important thing to know about the structure of an LED. If you are interested in the theory, we recommend watching the video:

Soldering Features

There are usually no difficulties in soldering DIP type LEDs. Knowing the simple rules of soldering, it’s difficult to make a mistake:

Soldering LEDs is, in principle, not difficult. Small problems regarding how to properly solder a diode appear when working with the SMD type. The fact is that these diodes do not have current-carrying legs; instead, they have contact pads. And, as a rule, SMDs are soldered into boards or tapes.

Soldering SMD parts without a hair dryer

Everyone understands how you can, using a regular 40-watt EPSN soldering iron and a multimeter, independently repair various electronic equipment with lead-out parts. But such parts 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 are now based on SMD element base.

Radio components on the SMD board

So what if we don’t know how to dismantle and solder back SMD radio components, because then we won’t be able to carry out at least 70% of possible equipment repairs on our own. Someone who is not very familiar with the topic of installation and disassembly may say that for this you need a soldering station and a soldering hair dryer, various nozzles and tips for them, no-clean flux, such as RMA-223, and the like, which is usually not available in a home craftsman’s workshop.

Soldering Station

I have at home 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 have your equipment repaired, on the road to order, or while visiting friends? Is it inconvenient to disassemble and bring the defective board home, or to a workshop where the appropriate soldering equipment is available, for one reason or another? It turns out there is a way out, and it’s quite simple. What do we need for this?

What you need for good soldering

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

• 2. Soldering iron EPSN 40-65 watts with a tip sharpened to 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 via a Dimmer, a device for regulating the power of the soldering iron. You can have one like the one in the photo below, very convenient.

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

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

• 5. SKF 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 flux residue remover, or 646 solvent, and a small brush with medium-hard bristles, which is usually used in school, for painting in art lessons.

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

• 8. Tweezers, preferably curved, L-shaped.

Wiring of planar parts

So, how does the process itself work? Read something here. We bite off small pieces of Rose or Wood solder (alloy). We apply our flux liberally to all contacts of the microcircuit.

We put a drop of solder on Rose, on both sides of the microcircuit, where the contacts are located. We turn on the soldering iron and set it using 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 pass the tip of a heated soldering iron along all the legs of the microcircuit, on both sides.

Dismantling using Rose alloy

In this case, the contacts of the microcircuit will close, 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 using the dismantling braid.

So, we took hold of our microcircuit with tweezers, along the edges, where the legs are missing.

Typically, the length of the microcircuit, where we hold it with tweezers, allows us to simultaneously move the soldering iron tip between the tips of the tweezers, alternately on both sides of the microcircuit, where the contacts are located, and slightly pull it up with tweezers.

Due to the fact that when melting Rose or Wood alloy, which have a very low melting point (about 100 degrees), relative to lead-free solder, and even ordinary POS-61, and moving with the solder on the contacts, it thereby reduces the overall melting temperature of the solder .

Dismantling microcircuits using braid

And thus the microcircuit is dismantled without dangerous overheating. On the board we have the remains of solder, Rose alloy and lead-free, in the form of sticky contacts. To bring the board back to normal, we take the dismantling braid; if the flux is liquid, you can even dip its tip into it, and place it on the solder “snot” that has formed on the board. Then we heat it from above, pressing it with the tip of a soldering iron, and run the braid along the contacts.

Soldering braided radio components

Thus, all the solder from the contacts is absorbed into the braiding, transferred to it, and the contacts on the board are completely cleared of solder.

Then the same procedure must be done with all the contacts of the microcircuit, if we are going to solder the microcircuit into another board, or into the same one, for example, after flashing it using a programmer, if it is a Flash memory chip containing the BIOS firmware of a motherboard, or monitor, or what or other technology.

This procedure must be performed to clean the microcircuit contacts from excess solder. After this, we apply the flux again, place 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.

For what purpose are we leaving this place? So that you can lightly touch the contacts with a soldering iron tip and 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” and will not 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 flux inside, bring it to each contact of the microcircuit, and simultaneously touch the tip of the soldering iron tip, the solder, and each contact of the microcircuit.

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

All we have to do is wash off the remaining flux from the board with 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 rinsing are very volatile. 646 solvent, in particular, is based on acetone.

Inscriptions, silk-screen printing on the board, and solder mask are not washed off or dissolved.

The only thing is that dismantling a microcircuit in a Soic-16 or more multi-pin package in this way will be problematic due to difficulties with simultaneous heating and a large number of legs. Happy soldering everyone, and fewer overheated microcircuits! Especially for Radio circuits - AKV .

   Forum

   Discuss the article Soldering SMD parts without a hair dryer

Source: https://radioskot.ru/publ/konstruktiv/pajka_smd_detalej_bez_fena/13-1-0-1155

What soldering iron to solder SMD LEDs

Everyone understands how you can, using a regular 40-watt EPSN soldering iron and a multimeter, independently repair various electronic equipment with lead-out parts. But such parts 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 are now based on SMD element base.

Radio components on the SMD board

So what can we do if we don’t know how to dismantle and solder back SMD radio components, because then we won’t be able to carry out at least 70% of possible equipment repairs ourselves. Someone who is not very familiar with the topic of installation and disassembly may say that this requires a soldering station and a soldering hair dryer, various attachments and tips for them, no-clean flux, such as RMA-223, and the like, which is usually not needed in a home craftsman’s workshop. can not be.

I have at home 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 have your equipment repaired, on the road to order, or while visiting friends? Is it inconvenient to disassemble and bring the defective board home, or to a workshop where the appropriate soldering equipment is available, for one reason or another? It turns out there is a way out, and it’s quite simple. What do we need for this?

How to solder SMD LEDs correctly

The installation of electronic circuit components is carried out in different ways. One of the most common options is soldering, which ensures reliable contact and strong attachment of parts to the printed circuit board.

It is not very difficult and is accessible even to novice radio amateurs. Soldering SMD LEDs has different features and rules. They are designed to preserve the elements and protect them from overheating. Failure to comply with the requirements leads to the loss of lamps, so it would be useful to consider the issue in more detail.

Basic soldering principles and common mistakes

The process of soldering SMD LEDs consists of applying a thin layer of solder (a low-melting tin-lead alloy with various additives) simultaneously to the contacts of the attached part and the current-carrying tracks of the printed circuit board. Physical processes used:

• wetting of metals with melt;
• capillary impregnation of small gaps between contacts, ensuring connection both mechanically and electrically.

In order to solder SMD diodes, it is necessary to use a special soldering iron with low power and limit the time of contact of the LED device with the hot working part. Experts recommend not to exceed 3-5 seconds. A common mistake is to use soldering irons with a thin tip. This reduces the efficiency of heat transfer and does not allow high-quality heating of the contacts and traces of the printed circuit board.

Experienced people recommend using a normal tip, ground at an angle. The large mass will ensure rapid heating of the pads and melting of the solder, eliminating overheating of the LED. Liquid solder, under the influence of wetting and capillary absorption effects, flows into the smallest gaps between the element legs and the printed circuit board track, after which the hot soldering iron is removed to the side. The solder hardens and creates a monolithic area of ​​strong connection of parts.

The second error leading to LED failure is overheating. Excessively long contact of the soldering iron with the legs of the LED element leads to an increase in the temperature of the emitting crystal. If you do not constantly control the duration of contact of the tip with the part, it will not be possible to avoid excessive heating.

Factory soldering

In the factory, other soldering technologies are used that allow several boards to be soldered simultaneously. A special robot installs the necessary elements on the base, on the working side of which solder paste is applied using silk-screen printing.

It contains solder and flux; when heated, they change phase and perform their tasks.

The flux degreases the contacts and provides wetting, and the solder, under the action of capillary effect, flows into the gaps of the connections and ensures a strong connection of the SMD elements.

The process takes place in a special oven, where the board is kept for a certain time. The contact duration and heating mode are selected in such a way as not to harm SMD LEDs. The procedure occurs quite quickly and ensures soldering of elements in industrial quantities.

Important! It will not be possible to repeat this technology at home, since you need to have a full set of equipment and materials. Therefore, it is important for hobbyists to master the process of manual soldering of SMD LEDs using conventional tools and materials.

Required materials and tools

To solder SMD LEDs you will need:

• soldering iron with the necessary parameters;
• side cutters, tweezers, scissors;
• mounting needle or thin awl;
• solder and flux. Regular rosin or a special liquid composition, which is an alcohol solution, will do. An aspirin tablet is often used;
• thin brush for applying liquid flux;
• a magnifying glass on an adjustable stand (bracket), which is used by jewelers;
• soldering gun (component of a soldering station).

It will not be possible to do without flux, since molten solder without it does not wet the contacts and does not settle on the metal. Experts do not recommend an alcohol solution of rosin, as it is ineffective and leaves an indelible white residue.

Choosing a soldering iron is an important preparation step. The best option is a soldering station with a temperature control function. However, a regular low-voltage unit with a supply voltage of 12 to 36 V and a power of 20-30 W is also suitable. It is not recommended to work with a standard 220 V device, as their tip gets too hot. As a result, the flux evaporates faster than it should, not performing its task within the required limits. The maximum heating temperature is 260°.

The type of sting tip is of great importance. A regular cone is not the best option; the optimal choice would be the so-called. microwave. This is a rod cut at approximately 45° with a small recess made in the axial direction. It is filled with liquid solder and allows you to more efficiently apply the material to the SMD LED pads and boards. If necessary, the microwave acts as a suction for excess solder, which avoids drips and drips.

The optimal type of solder is a thin wire with rosin inside. This type allows you to successfully solder LEDs with almost any soldering iron.

How to solder SMD components

Installation of LED elements is technologically significantly different from connecting a lamp. Soldering SMD LEDs requires some experience and skill. If there are none, it is recommended to first practice on some unnecessary pieces of wire.

This will help you master the art of soldering and keep your LEDs in working order. Before starting work, you should inspect the surface of the board.

If it is coated with varnish or a layer of silicone, the current-carrying paths to which the LEDs will be soldered should be freed from them.

The specificity of installing SMD LEDs is the absence of conventional long leads. The elements are installed on the board and soldered to the tracks, for which there are small areas on the sides of the LED device housings. The work requires accuracy and attention.

It is important to remember the danger of heating, reducing the time the soldering iron touches SMD parts as much as possible. If there is no appropriate tool, a copper wire about 1 mm thick is wound around the tip of a conventional soldering iron.

One end of this winding serves as a sting, the heating temperature of which is significantly lower than that of the main element. Let's look at the procedure in more detail:

Work order

The soldering process consists of the following operations:

• removing a burnt out LED (if necessary);
• cleaning conductive paths, applying flux to the soldering area;
• installing a new LED element in place;
• soldering of contacts;
• cleaning the soldering area from flux residues.

It is necessary to constantly remember the contact warm-up time, reducing it as much as possible to acceptable values. The finished soldering should be neat, smooth, without solder sagging or drips. Excess material can be collected with a piece of braided screen, heating the solder and touching it with a bundle of wires.  

How to solder with a hair dryer

Soldering with a hair dryer is somewhat reminiscent of the industrial method of mounting SMD LEDs, only instead of an oven with the required temperature, a special hair dryer is used. The process is carried out in stages:

• We apply special thermal paste to the surface of the board. You should not completely cover the base with it; it is enough to apply the material only to the contact pads;
• install the LED using tweezers;
• we direct the flow of hot air and solder the board to the LED element. To protect against overheating, it is recommended to cover it with a metal object.

When hot air is supplied, the pasta melts, forming a layer of flux and liquid solder. The flux evaporates quickly, leaving a strong seal.

A hair dryer is convenient to use for dismantling work. If you need to unsolder many LEDs at once (for example, to replace burnt-out elements on a linear backlight), a hair dryer will quickly heat the board and easily remove even glued parts.

Soldering silicone coated tape

Silicone protection is applied to prevent contact of the tape with moisture. For soldering, it is necessary to remove the coating layer. To do this, cut the tape with a sharp knife and carefully remove the protection.

After this, the current-carrying paths are thoroughly cleaned and degreased, flux is applied and the LEDs are soldered. At the end of the work, it is necessary to re-apply a layer of transparent silicone to the cleaned area.

You can use a regular plumbing compound, which hardens for about a day (depending on the thickness of the layer).

Main conclusions

Soldering SMD LEDs is not very difficult, but requires care and caution. You should remember the danger of overheating of the elements, which will result in their failure. It is necessary to ensure compliance with the following conditions:

• use a low-power soldering iron with a heating temperature no higher than 260°;
• use high-quality flux (experts recommend a special composition for soldering aluminum);
• limit the contact time of LEDs with the soldering iron.

In addition, you must remember to maintain polarity and monitor the condition of the current-carrying paths. Please share your options for soldering SMD LEDs in the comments.

PreviousNext

Source: https://svetilnik.info/svetodiody/pajka-svetodiodov-smd.html

Soldering LEDs correctly - Build Tool

13.06.2019

When connecting and installing an LED strip, many people are put off by the need to solder it.

For example, this can be encountered when the tape needs to be shortened, cut, rotated, and then connected to the contact pads. Or simply connect it with wires to a power supply or controller.

People think that only professional radio amateurs and electronics engineers can do this correctly. Therefore, they prefer to buy some connectors or connecting wires for connection.

However, only soldering can make a truly high-quality connection in LED strips.

Disadvantages of connecting connectors

When using a connector, the contact on the tape and the contact on the connector have a fairly small contact area after snapping into place. What does this ultimately reflect?

Due to the reduction in area, heating occurs. Firstly, this affects the LEDs themselves located near the connection point. They begin to degrade and lose brightness faster than the rest of their “brothers” in the backlight.

And secondly, copper without soldering and tinning tends to first darken and then oxidize, forming a greenish coating. That is, oxides are formed that do not conduct electric current. This is typical even for not very small contacts on switches with high currents.

If your contact heats up, the oxidation process will occur much faster and more intensely. Eventually normal contact simply disappears. The LED strip begins to blink spontaneously, go out, etc.

Even if you provide a sufficient contact area, but do not protect the contacts in any way, oxidation processes will still occur sooner or later.

Therefore, soldering is the most reliable and durable way to connect and connect LED strips.

Tools and materials for soldering

This process is not at all complicated; it is enough to have the necessary materials and follow a few basic rules.

Here's everything you'll need:

• soldering iron with a power of no more than 25-40W  

• thin copper wires with a cross section of 0.5-0.75mm2  

• knife or stripper for stripping insulation from wires  

• toothpick for convenient application of flux  

• tin-lead solder POS-60 or equivalent  

Briefly, the entire process should look like this:

1Prepare the soldering iron2Dip into rosin3Dip into solder4Again into rosin

5Soldering wires and tapes

And now all this in more detail and with certain nuances.

So, you have a tape and contact points on it where you should solder the wires.

First of all, find the marking which contact is “positive” and which is “negative”.

On RGB options there will be one common plus (+12V) and three minuses (RGB). This is important in the future for maintaining polarity and supplying power from the unit.

Strip the ends of the wires from insulation. It is advisable to take multi-colored cores so as not to be confused with the polarity in the future.

Heat up the soldering iron, touch the solder and lower the core into the rosin.

After which, when pulling out the core, immediately bring the soldering iron tip with tin to it.
The tinning process should happen automatically. Do the procedure a couple of times to completely cover the copper core on all sides.

Now you need to tin the contact points on the LED strip. This is best done using flux.

Before doing this, do not forget to thoroughly clean the soldering iron tip.

Dip it in rosin and clean off all excess. This can be done with a special sponge, a simple knife if the carbon deposits are completely ingrained, or use a metal sponge.

The main thing is to prevent any foreign elements from getting onto the contact pad.

Next, take a very small amount of flux on the tip of a toothpick and apply it to the LED strip.

It is important that the soldering iron is low-power, with a heating temperature of no more than 250 degrees.

What if you don't have a regulator? How to determine the heating temperature?

• look at the sting. It must be clean, not hot.  

• when dipping in rosin, the latter should not boil  

• there should just be a little smoke coming from the sting  

The maximum allowable time for applying the tip to the LED strip is no more than 5 seconds. When using flux, this happens much faster, 1-2 seconds.

As a result, you should end up with two tin tubercles, in which you will then need to “drown” the connecting wires.

Before directly soldering the wires themselves, try on their ends.

They must be stripped exactly along the length of the soldering areas. Usually this is no more than 2mm.

If the bare ends are long enough, then when bent they can easily short out each other. Therefore, always bite off the excess, leaving the tip as short as possible.

Touch the tip of the tubercle on the contact of the LED strip with this tip and apply a soldering iron on top for 1 second. The tin melts and the wire sinks, as if drowning in it. Do the same with the second wire.

As a result, you should end up with a fairly large contact area. But most importantly, this place is covered on all sides with a tin “cushion”, which reliably protects the contacts from oxidation.

For even greater strength, the soldering area can be filled with hot glue and heat shrink applied on top. Then the wires will not fall off even with constant bending.

Soldering silicone coated tape

If the LED strip is completely covered with silicone, there is nothing tricky about soldering it either.

Simply, carefully clean off the silicone from the soldering points with a utility knife, and follow the entire procedure described above.

Silicone here plays the role of additional insulation of LEDs from external conditions.

If you have a tape with IP68 protection, then after all the work with the soldering iron, you will have to reseal the end with the wires.

To do this, you need to try to push the LED strip back into the protective shell and fill the entire space in this place with silicone.

Filling depth is at least 10mm. Then install the plug, also pre-lubricated inside with silicone. The wires are passed through the holes in the plug.

Overlapping connection without wires

To solder two overlapped strips, one of its ends must be tinned on both sides. To do this, carefully remove the double-sided tape from the back side and use a knife to clean the layer of glue.

After this, you place one piece (the one that was treated on both sides) on the other (tinned only on top).

Align the contacts with each other and heat the top strip with a soldering iron so that the solder melts on the bottom too.

True, such a connection is not considered particularly reliable, so it is better to use traditional wires for this purpose.

If you have a long LED strip (up to 5 meters), then it is advisable to solder the power wires to it on both sides. This will ensure that all LEDs glow evenly.

What is the best way to solder wires to an extended LED backlight consisting of several parallel sections?

Typically, for such a connection there is a common power bus (wires with a cross-section of 1.5 mm2), and separate pieces of tape that need to be soldered and connected to this bus.

In this case, it is best to solder the wires to separate pieces at an angle of 90 degrees.

And so as not to put one wire on top of another

The “plus” connection can be made not in the same contact place as the “minus”, but in the next section of the module.

This will not affect the glow of the LEDs in any way.

If you have an RGB LED strip, then you probably noticed that its solder contacts are quite close to each other.

Therefore, when soldering such a backlight, be sure to check that the pads do not short out with a tin track.

If this does happen and you haven’t noticed it, then the minimum that will happen is that the colors will get mixed up, or some of them will disappear.

But if the positive contact and any of the minuses close, this can lead to failure of the power supply or the tape itself.

What to do if the pads are still covered with solder? To fix this, bring the tip of the soldering iron again to the pads, heat the tin and run an ordinary toothpick between the contacts.

The soldering process for RGB is the same as for a simple single-color LED strip. Apply flux (4 drops).

Create tin “pads”.

After that, you recess the wires inside one by one.

To make a branch from 4 or even 5 (RGBW) contacts to the side, and at the same time not interfere with the connection of the second piece of tape, solder only one contact on each module.

Or solder all 4 wires not at the very end, but on the penultimate module.

The tape will still glow properly, no matter where the soldering is.

Thus, having a normal soldering iron, solder and good flux, any beginner can learn how to solder an LED strip.

Of course, installation with connectors is much faster and does not require special tools.

But if you are making LED ceiling lighting for yourself and for many years to come, then losing an extra 10-15 minutes during installation will pay off in the future with a couple of extra years of reliable operation.

However, it is still not worth completely abolishing connecting connectors. If you are assembling some kind of lighting of a complex design, especially high under the ceiling, then you cannot do without them.

When you move the soldering iron from bottom to top, a drop of solder does not always stick. It is imperative to wear safety glasses when doing this type of work.

Therefore, with complex designs, it is certainly better to opt for connectors.

It will be easier to rearrange the backlight segments and change the configuration.

1Even after one-time soldering and desoldering of wires and tape, it is not advisable to make a connection with a connector in this place.

Due to the difference in the thickness of the tin layers on the plus and minus, somewhere the contact may be better, but somewhere much worse. Therefore, decide in advance which connection you will use.

2Heating the soldering iron to more than 250-300 degrees and soldering with such a tip.

Signs by which this can be determined without having a built-in regulator:

• the soldering iron really starts to smoke  

• rosin or flux literally sizzles, boils  

• solder does not stick well to the tip 

• the surface of the solder at the tip of the tip looks like loose drops with a matte surface, but should shine 

• The soldering iron tip becomes covered with black soot 

3Use of acid or active flux instead of neutral.

Acid tends to corrode the area around the contact, and the active flux reacts with the metal for a long time after soldering. All this, when manipulating the wires, can lead to damage to the contact even at the time of installation.

4 Unfortunately, cheap Chinese LED strips often use strange alloys instead of copper contacts.

You seem to follow all the rules of soldering: heating up the soldering iron, cleaning it, flux, etc., but the wires still don’t want to be soldered.

Of course, there are no mistakes of yours here, except for one - buying and choosing such a cheap tape.

Source: https://pgmk96.ru/drugoe/pravilno-payaem-svetodiody.html

How to solder SMD with a simple soldering iron

Sometimes it happens that you urgently need to solder an SMD element, but there are no special tools at hand. Just a regular soldering iron, solder and rosin. In this case, it is difficult to solder a miniature SMD element, but it is possible if you know certain features of such soldering.

I use some skills that I haven’t seen described anywhere, so I decided to share them ( at the end of the note - see the video of the process ). SMD housing - 0805.

It is impossible to make the sting not tremble

Not a single person is able to make sure that a tool (any tool - not just a soldering iron ) does not tremble in his hands. Once upon a time I read about masters who paint miniature paintings or murals. The technology they use in their work was described there. Its essence is that it is necessary to coordinate the movements of the hand with the beats of the heart. The inevitable actually occurs from heartbeats .

There is no need to fight trembling - it is useless. You need to learn to adapt to it.

Soldering SMD LEDs using a soldering table

Hi all. Today we’ll talk about soldering SMD LEDs, namely, speeding up this process.

Not long ago, they brought me a 47-inch TV with a faulty backlight for repair.

It had more than 100 LEDs on board, and in order to “make life easier” for the repairman, the manufacturer installed these LEDs on strips with an aluminum backing.

Of course, such strips are very heat-intensive, and soldering LEDs in the usual way (using a hair dryer as described in this article) turns out to be very labor-intensive. Nevertheless, everything was done, but the process took about two days with coffee breaks.  

After this repair, in the process of communicating with a familiar master, it turned out that many people no longer use a soldering hair dryer or soldering iron to replace LEDs, but use so-called soldering tables. It is this kind of device that we will now talk about.  

What is a soldering table for soldering LEDs?

The soldering table itself is an aluminum plate measuring 77 by 62 mm , inside of which there is a ceramic heater.

Such heaters are manufactured for different operating temperatures, from 75 degrees to 250 degrees. I was advised to buy 250 degrees, since with certain skills it is possible to solder LEDs at the highest speed.  

Having received such a heater, I began testing on a donor. 

Soldering table test

To check the operation, we used a faulty LED strip from an old TV. 

Having connected the heater to a 220 volt network, it was decided to measure the temperature of the heating element. 

Measuring the temperature of the soldering table with a thermocouple The result was 239 degrees. 

As a result, we have 239 degrees, which is within the error. 

Having first applied a little flux to the LED, I attached the bar to the heater.

LED removed

The LED was soldered within 5-7 seconds, which is very fast, but as you can see in the image, the PCB darkened a little. 

Next, I cleared the area of ​​old tin. I used braid for cleaning.  

The process of cleaning contacts from solder

After cleaning and wiping the board with alcohol, I decided to try soldering a new LED using soldering paste. 

I had solder paste from the mechanical company with a tin content of 63% and a lead content of 37%. I use this paste for rolling balls on chips.

Solder paste

Using a toothpick, I applied just a little solder paste to each contact and installed the LED.

solder paste on the contacts Installed the LED on the solder paste Soldering process

The LED was successfully soldered within 5 seconds. Having washed off the remaining flux, we have a perfectly soldered LED and a not very good darkened strip.  

Final version

Eliminating this shortcoming is not a problem; you can simply glue the lens reflector. In 80 percent of cases I glue such reflectors, since with them it will be possible to focus the lens much faster.  

LED reflectors LED with lens.

Conclusion

I will definitely use this method of replacing LEDs. I like the fact that you can desolder all the LEDs within a minute. After that, within 5 minutes you can clean the pads, apply solder paste, install new LEDs and quickly solder everything back.  

The only significant drawback is the darkening of the PCB, but using reflectors all this can be corrected. 

All links to LEDs and the soldering table itself are posted below. Thank you all for watching and good luck with your repairs. I look forward to your feedback on this method.  

TABLE-OVEN FOR LED SOLDERING
REFLECTOR LENSES FOR LED BACKLIGHTING
LEDS, GLUE FOR LED BACKLIGHTING TV MATRIX
SOLDERING PASTE

(5 5,00 out of 5)

Source: https://remonter.info/pajka-smd-svetodiodov-s-pomoshhyu-payalnogo-stola/