How to Desolder a Chip with a Soldering Iron - Metals and Their Processing

How to solder microcircuits? Soldering iron for radio components: which one to choose?

Inexperienced radio amateurs sometimes face the problem of replacing microcircuits on a printed circuit board. When carrying out a seemingly simple process of dismantling radio components, detachment of contact pads or damage to a serviceable element often occurs due to overheating of its housing. This problem arises due to the need to heat a large number of legs at the same time or remove solder from the contacts one by one, which leads to their breakage.

Therefore, for high-quality dismantling, you need to thoroughly study the question of how to desolder microcircuits, as well as which soldering iron to choose for removing radio components from a printed circuit board.

Basic methods of dismantling microcircuits

Before you start soldering microcircuits, you need to determine what type of part body is used in a particular case. Despite the wide variety of radio components, there are two main types of mounting microcircuits on a printed circuit board:

the legs of the microcircuit are inserted inside special holes on the board;
Surface mounting involves the presence of contact pads on the board, to which the legs of the radio component are soldered.

There are several methods using various soldering tools that can effectively simplify the process of dismantling microcircuits:

heating the junction of the contact pad with the leg of the radio component with one soldering iron;
dismantling the microcircuit using the metal braid of a coaxial cable;
the use of special suction to help remove solder from the soldering site;
using a medical needle for dismantling;
soldering the microcircuit using metal heat-conducting plates;
the use of special compositions with a low melting point (Rose or Wood alloy).

The choice of dismantling method largely depends on knowledge of the technical characteristics of the microcircuit (heating temperature, type of housing), as well as on the practical skills of the radio amateur.

Unsoldering a microcircuit using a conventional soldering iron is considered a difficult task. This work can be performed by an experienced radio amateur without damaging the contacts of the printed circuit board or the serviceable part.

The essence of the method is to remove molten solder from the legs of the microcircuit one by one. In this case, it is important that the soldering iron tip is wetted with liquid rosin (flux) each time, and then the remaining solder is removed by wiping it on a damp rag.

Completion of dismantling the chip is performed after removing the solder. To do this, the part is pryed off from the side of the board and separated after slightly warming up the contact pads. The force should be insignificant so as not to damage the contact tracks.

Application of copper braid

Before soldering microcircuits using this method, it is necessary to perform several preparatory operations. To do this, you need to carefully remove the shielding braid from a small piece of coaxial cable.

Next you need:

clean and tin the soldering iron tip;
moisten a piece of copper screen with flux;
attach the braid to the contacts of the microcircuit;
heat the protective screen with a soldering iron, the solder will saturate the braid and free the legs of the radio component.

The braid is a good heat dissipating element, which reduces the possibility of overheating of the soldering area. In the retail chain you can purchase ready-made braid impregnated with rosin. But due to the considerable cost and high consumption of material, for one-time work it is preferable to make it yourself.

Vacuum suction greatly simplifies the process of dismantling microcircuits, and is also a very useful tool for soldering radio components, efficiently removing excess solder from the joint.

Industrial suction consists of the following elements:

housings with a vacuum flask;
heat-resistant spout;
working piston;
return spring.

Before soldering the microcircuits, the suction must be brought into working position. To do this, you need to press the piston and fix it with a locking device.

The dismantling technology is as follows:

Heat the soldering iron to the optimal temperature.
Melt the solder on the contact of the radio component.
We press the suction nozzle to the connection point.
Press the lock button. In this case, a vacuum is created inside the flask due to the movement of the piston, and molten tin is sucked into the device.

When performing a large volume of work, the suction unit must be cleaned periodically.

To perform one-time work, you can do the suction yourself. To do this, you need to remove the piston from a simple medical syringe and insert a spring for return movement. You need to put a metal tube of a suitable diameter on the spout of the device. The device is ready.

Dismantling a microcircuit using a needle

Radio amateurs often use a needle from a medical syringe to solder microcircuits. The diameter of the needle is selected so that it is inserted into the hole on the board, and the leg of the part goes inside it. Having selected such a needle, you need to grind off the oblique cut of the tip with a needle file to a right angle.

Having placed the needle on the leg of the microcircuit, you need to heat the contact point on the board with a soldering iron. Then, while the solder is in a molten state, rotate the needle with gentle movements and push it into the hole. As a result of such actions, the leg of the part becomes isolated from the board. Next, the same operation is performed with the remaining legs of the microcircuit.

Also, special factory devices can be used to clean contacts.

Soldering chips using a plate

The presence of several legs on the microcircuit complicates the process of simultaneously desoldering them from the board. Therefore, radio amateurs often use special metal heat-conducting nozzles to warm up several contacts at once.

The process of such dismantling looks simple. A special plate or a simple razor blade is applied simultaneously to several contacts. The blade is then heated to the melting temperature of the solder. Since the heating area is increased, you need to use a soldering iron with 40 W power.

While heating the heat-conducting plate, it is recommended to rock the microcircuit a little to simplify the process of freeing the legs from the solder. After removing one row of contacts, the plate is transferred to another row of legs and a similar operation is performed until the part is completely freed from the board.

Use of special alloys for dismantling

A distinctive feature of Rose or Wood alloys is their low melting point. Thus, the Rose alloy has a melting point almost two times lower than tin, about 100 ℃. This property of the material allows it to be effectively used in the process of soldering small radio components and microcircuits.

Soldering technology involves applying alloy granules to the contacts, after which this area is heated with a soldering iron. Thanks to the alloy, the solder melts evenly at low temperatures. All that remains is to carefully pry off the part with tweezers.

Wood's alloy has an even lower melting point (65-72 ℃), but it contains toxic cadmium, which significantly limits its use at home.

It is worth noting that a novice radio amateur, before starting to dismantle microcircuits, needs to figure out which soldering iron to choose for radio components. This will allow you to complete the task much better and more efficiently.

For long-term operation, a soldering iron must be light in weight, since a heavy device quickly loads the radio amateur’s hand, causing his movements to become inaccurate.

Structurally, the soldering iron consists of the following elements:

The handle of the device can be plastic or wooden. Plastic handles can heat up significantly, so they are used in low-power soldering irons. Powerful devices are most often equipped with wooden holders.
The nichrome heating element consists of mica, on top of which a spiral is wound. If the wire burns out, it is very difficult to replace it yourself. A soldering iron with a ceramic heater does not have this drawback, but is a very fragile device. If you avoid dropping the tool, the ceramic will last a very long time.
The soldering iron tip is the main working surface. The tip is usually made of copper. If the tip burns, clean it with a finely cut file. There are soldering irons with replaceable tips.

Classification of soldering irons by power

The power of a soldering iron is its main characteristic, which significantly affects the quality of the work. The heating temperature of the soldering iron tip directly depends on the value of this parameter.

By power, soldering irons can be divided into the following groups:

Soldering irons with a power of up to 10 W are used to work with thin conductors and small radio components.
Soldering parts on printed circuit boards is most efficiently done with soldering irons with a power of 15-30 W.
Soldering irons 40-60 W are most often used for work at home.
Electrical wires of large cross-section are connected by devices with a power of 80-100 W.
Soldering irons with a power of 200 W are designed for soldering metal structures using soldering acid.

There are several methods for desoldering microcircuits from a printed circuit board, which have their own advantages and disadvantages. The radio amateur himself must decide which method to use in a particular situation, based on his experience and the technical capabilities of the equipment.

Source: https://FB.ru/article/455810/kak-vyipaivat-mikroshemyi-payalnik-dlya-radiodetaley-kakoy-vyibrat

What soldering iron should I use to solder a motherboard?

Soldering is one of the most effective and simplest ways to connect metal materials, wires and parts.

Although soldering work is considered simple, you will need certain knowledge and skills. The most common type of soldering is work done with a soldering iron.

To know how to properly solder with a soldering iron with rosin or other types of fluxes, you need to delve a little deeper into the topic.

There are different types of soldering irons that differ in power.

Electric soldering irons are the most common and operate on electricity.
Gas - they work using a gas burner.
Thermal air - use air flow.
Induction soldering irons - their work is based on heating the tip with a magnetic field.

One of the varieties of this tool is also a soldering iron for rhinestones. It is considered one of the most common elements when working with thermal rhinestones. The technology for using this product is very simple - put the rhinestone on the fabric and apply a soldering iron on top, the glue penetrates the fabric and securely holds them together.

In everyday life, electric soldering irons are most often used, having different powers for different types of work.

For soldering electronic components, soldering irons with a power of up to 40 W are used; if the parts have a wall thickness of no more than 1 millimeter, then the device has a power of 80 to 100 W.

For thicker-walled parts, soldering irons with a power of over 100 W are used.

Solders and Fluxes

Before you begin soldering work, you need to select solders and fluxes. For electrical soldering, there are different types of solder, which can be soft or hard.

Soft ones include tin-lead alloys, which have a low melting point and are not particularly strong. It is not recommended to use them if the soldering temperature exceeds 100 degrees Celsius. Refractory alloys include silver and copper alloys.

They are perfect for those connections where there will only be a static load on the material, since such alloys are very fragile.

Fluxes are responsible for how the metal will be soldered and how strong the connection will be. Its task is to remove the metal oxide film.

The following fluxes are used: various mixtures of rosin and acid.

Rosin mixtures are commonly used when soldering electronics, while acid is used to join small wires and small contacts.

Security measures

Organize your workplace; it should be bright and ventilated, as the soldering process produces gases that are harmful to health. It is also recommended to wear glasses to protect your eyes from splashes of molten metal or flux.

Tinning the tip

The tip is a cylindrical rod made of copper. Its shape can be changed depending on the type of work.

For example, it can be flattened into the shape of a screwdriver tip. This type of sharpening is used when soldering massive parts.

You can also grind off a pyramid-shaped tip; it should be used when soldering small parts.

Tinning is used at the preparatory stage and involves covering the tip with a thin layer of solder for better contact with the surface to be connected. This operation will protect the tip from rapid wear and corrosion.

Soldering conductors

To know how to solder a wire to a contact, you just need to practice a little.

Before proceeding directly to soldering, you should thoroughly warm up the soldering tool; when you use it for the first time, the soldering iron begins to smoke - this burns out the lubricant used in its production. It needs to be allowed to cool, then turned on again.

Next, the first thing you need to do is clean the insulation; it can be easily removed with wire cutters in one movement. Insulation in the form of enamel, paint or fabric wrapping must first be burned. Then go over the wires with sandpaper or resort to a chemical method - put the wire on an aspirin tablet and heat it with a soldering iron.

The next step is to apply a little flux to the wire you are going to solder, then use a soldering iron to begin tinning. Immediately after this, you need to connect the two ends of the wire, carefully heat the contact point until the solder melts and quickly remove the soldering iron so as not to overheat the parts.

Modern electronic devices do not have wires. The connection is made by soldering the contact surface.

For such types of work, use a low-power soldering iron with a power of 10-12 W. Before use, you can make several copper tips with branches for it.

They will allow you to use the tool when working with LEDs and various radio elements.

Working with the board

Before soldering the wire to the board , you need to perform certain actions:

Insert the part into the previously prepared place.
Bring the heated soldering iron along with the solder to the soldering area.
Apply a thin layer of solder to the contacts of the board and the pins of the part.
Quickly remove the soldering tool.

The heated soldering iron tip should be in contact with the board and contacts at the same time. We remove it only when the soldering area is covered with a thin layer of solder. Excess solder can be removed with copper wire; you just need to bring it to the soldering site.

Induction soldering

This type of soldering is widely used in industry and allows you to connect various conductive metals, such as copper, steel, aluminum, hard alloys, etc.

During the operation, non-contact heating occurs due to the formation of eddy currents. To protect parts from oxidation, induction soldering is carried out using fluxes or in a vacuum.

Common mistakes

Typical mistakes made by beginners:

Don't get lost
Overheat
Chemical destruction
Solder rolling

Failure to solder occurs due to the fact that the soldering iron was not warmed up enough , or the materials being soldered were too refractory, and the soldering iron had too little power.

Overheating is the exact opposite of unsoldering. The main reasons for overheating: using a soldering tool that is too powerful, or leaving it on the soldering area for too long.

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Chemical destruction appears at the soldering site due to incorrectly selected flux, and if washing is not carried out after soldering. This leads to corrosion and gradual destruction of the soldering area.

Proper care

A high-quality soldering iron is not a cheap tool, and like any other tool, it requires careful care. Basic rules for caring for it:

It is not recommended to turn on the soldering iron with the tip removed, as this leads to overheating of the element and significantly reduces the service life of the tool
Before first use, you need to coat the tip with high-quality flux and tin it.
After completing the work, you need to thoroughly clean the tip and tin it, this will help to quickly warm up the tool the next time you use it.
During soldering, you need to periodically apply solder to the tip of the soldering agent, so its tip will last you longer.

Source: https://ichudoru.com/kakim-payalnikom-payat-materinskuyu-platu/

How to properly desolder a microcircuit with a soldering iron

Before you desolder a microcircuit from a board with a soldering iron, you should watch a training video. What do you do when an electrical appliance fails? Most likely, you take it to the master, a check is performed, after which he informs you that you need to resolder the parts in the circuit. After which, he does the work, you pay the money. Undoubtedly, to become a master in this field you need to study and gain a lot of knowledge. But if you approach this issue from the other side, then starting from the basics you can learn to do a lot on your own.

Desiccant pump: how to use it correctly

A vacuum desoldering pump is a very useful tool for soldering various radio components, be it microcircuits, a transistor, or, for example, a diode. Also, high-quality removal of tin from the contacts will help solder the working part without much difficulty.

The desoldering pump consists of:

Vacuum flask, spout made of thermal material;
Return spring;
Piston.

A desalination pump can be purchased at a hardware store or specialty store.

Soldering radio components with a desoldering pump is quite simple. First of all, it is necessary to “cock” the destin pump. To do this, you need to fix it with a locking mechanism by pressing the piston (the fixation occurs automatically). Next, with a soldering iron heated to the optimal temperature, we melt the tin on the contact of the part, having previously attached a destin pump to the contact.

After the tin has melted, remove the soldering iron, press the tin pump to the desoldering area and press it tightly. Press the locking mechanism button. The piston, moving back through the flask, creates a vacuum, due to which the tin is sucked in.

When soldering a large number of radio components, do not forget to periodically disassemble and clean the desoldering pump.

If you don’t have a desoldering pump at hand, and the part needs to be unsoldered, then you can make one from a regular syringe with your own hands. To do this, you need to take a syringe (50 cc if possible). We take out the piston and place a return spring in the syringe flask (the spring should be no longer than the flask so as not to squeeze out the piston). All that remains is to protect the nose. This can be done with any metal tube of the appropriate diameter. And the homemade desoldering pump is ready for use.

Braid for desoldering parts

Many professionals, as well as radio amateurs, know firsthand about the advantages of such an auxiliary “tool” as a desoldering braid. Its correct use in work allows you to quickly and efficiently get rid of tin on contacts, without damaging them.

You can braid:

Buy in store. There are a huge number of species;
Make it yourself from scrap materials.

Soldering parts using braiding occurs as follows. The soldering iron heats up to the desired temperature. A braid is applied to the desired contact and the contact is heated with a soldering iron. Then, using small circular movements, remove the tin from the contact.

The braid is of good quality and is always impregnated with rosin at the manufacturer. When purchasing, check this important condition.

Buying braid will not be difficult. But due to its considerable cost and high consumption during operation, an excellent solution would be to make it yourself. To do this, you will need a coaxial (radio frequency) cable or old stranded wires of small cross-section.

You can make the braid for desoldering parts yourself, having previously studied the recommendations of specialists

To make a cable braid, you will need a small piece of it. The top insulation is removed. Then the copper braiding of the cable is removed (take small pieces, this will ensure convenient removal of the braiding). The removed braid must be flattened and impregnated with alcohol-rosin flux.

To make a braid of wires, you will need several small wires (suitable from headphones). The insulation is removed and several wires are twisted together. Next, they need to be flattened with a hammer. All that remains is to impregnate with flux.

How to desolder a microcircuit from a board with a hairdryer

The fastest way to unsolder a radio component, or unsolder large circuits, is to use a hair dryer. It is worth considering that this method may disrupt operation or damage the part. Therefore, in the future, before soldering a part removed using a hair dryer, it is necessary to check its functionality with a multimeter.

Source: https://MyTooling.ru/instrumenty/kak-pravilno-vypajat-mikroshemu-pajalnikom

How to desolder a microcircuit from a board with a soldering iron: 4 methods

Before you desolder a microcircuit from a board with a soldering iron, you should watch a training video. What do you do when an electrical appliance fails? Most likely, you take it to the master, a check is carried out, after which he informs you that you need to resolder the parts in the circuit. After which, he does the work, you pay the money. Undoubtedly, to become a master in this field you need to study and gain a lot of knowledge. But if you approach this issue from the other side, then starting from the basics you can learn to do a lot on your own.

The desoldering pump consists of:

Vacuum flask, spout made of thermal material;
Return spring;
Piston.

A desalination pump can be purchased at a hardware store or specialty store.

When soldering a large number of radio components, do not forget to periodically disassemble and clean the desoldering pump.

How to remove capacitors from a motherboard

Capacitors of various types perform an important function in the operation of any microcircuit. They pass or do not pass current, accumulate a certain charge, shift the phase and many more functions. And the failure of one of them affects the operation of the entire system. Therefore, timely replacement contributes to the uninterrupted operation of the circuit.

You don't need any special skills to remove capacitors from the motherboard.

To replace you will need:

Not many people know that capacitors have one feature - thick contact legs. Soldering capacitors is not difficult. But the process of soldering them is somewhat more complicated due to this feature. This is determined by the fact that the legs are very difficult to warm up. In order to make the work easier and faster, use the proposed method.

This method will help to warm up the capacitor legs much better and avoid damage to nearby conductive tracks on the board.

A soldering iron or soldering station is heated to maximum temperature. A certain amount of solder is applied to the tip (to form a small drop). Next, using a heated drop of solder, we heat the legs of the capacitor to the desired temperature.

DIY desoldering pump (video)

Now, knowing several methods of soldering radio components and microcircuits, you can easily determine which one and in what case to use. And using some tricks will help you do the job competently and with understanding.

Source: https://www.6watt.ru/bytovaya-tekhnika/remont/kak-vypayat-mikroskhemu-iz-platy-payalnikom

How to solder contacts on a board

For professionals, the title of the article may cause a condescending smile. It would seem, what’s so complicated here? I cleaned the contacts, scooped up some solder with the nose of the soldering iron, and applied it to the connection point. For an experienced radio amateur, this process really does not cause problems. But if everyone (including professionals) knows how to solder correctly with a soldering iron, where do unsoldered boards, short circuits between adjacent contacts, and parts that fail due to overheating come from?

Our material will tell novice craftsmen how to learn to solder using traditional and non-standard methods, and for those who consider themselves professionals, it will help improve their skills.

What is soldering

Without referring to Wikipedia, we will explain in our own words. Soldering is the joining of metal contacts using a conductive melt, followed by its solidification. In this case, unlike welding, none of the parts being connected should melt during the process. Of course, after the conductive melt (solder) has solidified, reliable electrical conductivity of the connection must be ensured. Contact resistance cannot affect the characteristics of the electrical circuit.

General rules for working with a soldering iron (we will consider all these points in detail in the review)

The connection point must be mechanically cleaned of dirt, protective coating and oxides (if the dimensions and design of the parts and conductors allow). What you can focus on: some metals, in principle, cannot be cleaned of the oxide film, at least in air. Only under a continuous layer of special fluxes (we are talking about aluminum and alloys based on it). The fact is that the “winged metal” oxidizes instantly.
To degrease the connection point, special cleaners are used: fluxes. They should not have a destructive effect on the metal you are working with. Even if the joint seems perfectly clean, soldering without flux is almost impossible. When you touch the heated tip of a soldering iron, thermal oxidation occurs.

Important: metals used in electrical engineering (aluminum, copper, silver, gold) in their pure form have good adhesion.

Standard solders seem to stick to the surface, securely fixing after hardening. The oxide film layer not only prevents “sticking”, it is also a dielectric.

And when heated, fluxes activate their cleaning properties, and not only remove invisible contaminants, but also prevent oxidation.

Special fluxes have been developed for various materials. Even acids are used.

The shape and dimensions of the working tip of the soldering iron tip must correspond to the contacts and soldering conditions. The material does not matter: it can be copper, ceramics, or hard alloys, silver-plated.

Choice of power - the range of 25–60 W is suitable for soldering printed circuit boards. Too high a temperature can not only overheat the soldering area, some radio components fail when exposed to heat. The other side of the coin: low temperature will be removed from the soldering zone by massive contacts or a thick heat-conducting conductor. You will have to keep the tip in the working area for a long time - hence the overheating of the parts again. For example, when the question arises of how to solder a capacitor, it is important to know exactly the degree. The golden rule of soldering: high temperature and short-term heating. This skill comes only with experience.

Solder selection. From the point of view of adhesion, all types work well. That is, selecting contacts for a specific metal is not task No. 1. But the melting point should be treated carefully. On the one hand, low-melting compounds make it possible to minimize the thermal effect on parts. On the other hand, this creates two additional problems: Firstly, low-melting solder “unsolders off” just as quickly. If the temperature conditions of the contact connection are not very favorable, there is a possibility of loss of contact during operation. Secondly, you will definitely encounter the fact that the solder is already in a liquid state, and the contacts have not yet warmed up for normal adhesion. As a result, the soldering point again overheats.

Let us repeat, these are only theoretical principles, from which it is not yet clear how to solder with a soldering iron. You will see detailed instructions below.

Selecting a soldering iron

If you are not involved in radio work professionally (most likely this is the case, otherwise you would not have studied this material), you have in your arsenal an ordinary soldering iron in one copy. We are not talking about a soldering station at all, since it is quite expensive (albeit a very convenient kit). But for a novice master this is overkill.

Let's return to soldering irons. The classic is a nichrome heater and a copper tip. In fact, this is the best combination, but for manual control. No temperature control, smooth slow heating. At the same time, the copper tip holds the temperature perfectly, and often compensates for the heat dissipation at the soldering site. Another advantage is that the soft material allows you to mold any tip configuration. You can literally rivet and cut out a tip for a specific type of soldering.

The only drawback is that copper burns out quickly, and this type of tip is actually a consumable item. It constantly has to be sharpened with a file.

Tip: Be sure to use a hammer before shaping the tip with a file. Once the copper rod is sealed, it will last longer. A little lost time is more than compensated for by ease of use.

The illustration shows the classic “screwdriver” shape. A universal tip for most amateur jobs.

Source: https://vi-pole.ru/kak-propajat-kontakty-na-plate.html

How to safely remove a transistor, microcircuit, diode from a board

When repairing household appliances, a home mechanic is often faced with the need to replace electronic components located on circuit boards or mounted using a hinged method.

In this case, you must work carefully, otherwise you can damage the semiconductor layer, burn out the tracks, or even destroy the case.

In order to solder a transistor, microcircuit or diode, you need to know and follow certain installation rules. Read them in this article.

Temperature conditions

All electronic devices are designed to operate at normal temperatures. They cannot withstand overheating for a long time and do not respond well to pulsed temperature influences: the semiconductor junction fails, contacts are broken, and the housing of the radio component is depressurized.

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However, the main methods of their installation remain welding or soldering, which ensures the heating of the contact pads and their connection when cooling.

The brands of low-melting solders used, such as POS-60 or POS-40, begin to transform into a liquid state when heated to 183 degrees, and when cooled in air, they quickly cool down and create reliable contact.

The safety of the transistor, diode, microcircuit, capacitor is ensured due to the short time of melting and hardening of the solder on the leg of the radio component.

Board design

To ensure safe soldering, you should imagine the design of the board on which the radio component is attached. In practice, the most common models are with:

one;
or two layers of copper foil conductors onto which solder is applied.

They are glued onto dielectric plates made of fiberglass or getinax.

In addition to these models, special high-precision electronic devices use multilayer boards with a complex arrangement of conductive paths of various designs.

Installation of parts on them by soldering, using solder, is carried out by robots in a factory environment.

It is quite difficult for a home handyman to perform such work efficiently at home.

Old models

A properly selected soldering iron can ensure normal heating of the contact tracks of boards and semiconductor leads.

The old EPSI model of the “Moment” type with a power of 65 watts has a universal design. It is not difficult to make it with your own hands.

Previously, resistive type models with a heating element made of thin nichrome wire were widely used.

Modern soldering irons

For specific soldering conditions, you can now purchase various types of models equipped with all sorts of functions.

For example, a soldering iron with tin suction has been specially designed for soldering microcircuits, transistors and diodes.

It quickly heats up a layer of solidified solder and easily removes it in a liquid state from the contact pad.

Radio component holders

When heating the transistor leg for tinning and soldering, you should always remove the heat from the body and semiconductor layer with some metal object.

For this purpose, tweezers or alligator clips are usually used. However, it is most convenient to work with a medical instrument with thin legs, which surgeons use during operations.

Fixing electronic boards

Radio components and boards are usually small in size and require reliable fixation in space. Soldering them while hanging is dangerous: a small wrong movement can damage the entire structure.

When working with them, one hand is already occupied: it contains a soldering iron. And the second one needs to perform some additional actions. In this case, factory or homemade vices, holders, and clamps come to the rescue. They must be used.

Soldering needles

At the moment the solder melts, they are inserted inside the board sleeve to separate the leg of the radio component from the contact track.

A home craftsman can buy a ready-made kit in a store, for example, via the Internet in China or your city.

Medical syringe needles are well suited for the same purposes. Their tips need to be sharpened to a right angle.

Molten Tin Removal Tool

There are several ways to remove liquid solder from the melt site:

shaking onto the floor, table or other surface;
sweeping with a brush or brush;
suction;
absorption into a special braid.

The first two methods are extreme; they are used in extreme cases. For normal high-quality work, the last two methods are suitable.

Liquid tin suction method

The tool adapted for it is called a tin pump. The appearance and design of one of the many models is shown in the picture.

Before work, the spring is cocked. When the solder is melted to a liquid state, the tip of the device is applied to it and by pressing a button, the force of the released spring is forced to move the piston to provide a vacuum, which draws the liquid metal into a special cavity.

Dismantling braid

It is made by weaving soft copper wire. Working with it is quite simple: a piece of braid is placed on the molten solder, and it quickly absorbs liquid tin.

Dismantling braid is sold in construction stores. An alternative can be a shielding core from an old coaxial cable for televisions, produced back in Soviet times. It is impregnated with a flux of alcohol and rosin.

Soldering conditions

When creating a workplace, you should pay special attention to its lighting. You cannot solder a radio component in semi-darkness. If your vision does not allow you to clearly see all the details, then you need to wear corrective glasses.

The electronic board must be clearly fixed in space, and the body must be in a stable position. It is best to work sitting or standing on both legs, holding the soldering iron confidently. After all, any wrong move will cause irreparable harm.

Technology for dismantling radio components

The tip of the soldering iron should be precisely placed on the layer of solder located in the socket of one leg of the transistor and quickly melt it.

Then a needle is inserted into this place from the reverse side and the tin is separated from the stem. If there is a dismantling braid or desoldering pump, then use them.

When the design of a radio component allows the use of a metal clamp to remove heat from the housing, then it must be used.

If the space for installing the soldering iron tip is very limited, then they work without using a heat remover.

In this case, special attention is paid to the length of time the radio component remains at elevated temperatures.

Features of dismantling microcircuits

The arrangement of the legs of the microcircuit strictly in a row allows you to melt the solder in all the sleeves of the contact pads of the board on one side of the case. This is a rather risky method, but in most cases with good skills it ends in success.

It is used when the tools described above for removing molten tin are not at hand, and the work needs to be done quickly.

Such operations are well provided by a transformer soldering iron with a tip made of copper wire, which can be bent to the shape of the legs of the microcircuit.

An awl or a thin screwdriver blade is placed under the microcircuit body. They act as a lever, move, and gradually pull out all the legs from their sockets at once at the moment the tin melts, but not before.

You should not try to completely remove the microcircuit in one go; it is enough to pull it out a little bit by bit on each side. At the same time, they monitor the temperature of the case and allow it to cool.

Using a similar method, I managed to remove the K554CA3 chip from the old board to work as a comparator in a homemade twilight switch.

In old boards, the legs of radio components were often bent on the reverse side and soldered. They are more difficult to dismantle. You will have to melt the tin on each leg, put a needle on the bend and use it to align the contact wire so that it comes out normally through the sleeve hole.

I suggest you watch the video by the owner of Radioblogful “How to desolder a microcircuit in three different ways”

To resolve any questions, use the ability to comment on the article. Now you can share it with your friends via social networks.

Source: https://HouseDiz.ru/kak-bezopasno-vypayat-tranzistor-mikrosxemu-diod-iz-platy/

Dismantling the microcircuit with a soldering iron

This is the most homeless and hemorrhagic trick when you have nothing but a soldering iron but need to desolder the microcircuit.

In order for this matter to go more or less smoothly, we clean the soldering iron from adhering solder. You can clean it with a special cellulose sponge or just with a damp cloth. Then, using a brush, coat all soldering joints with liquid flux; for this I use alcohol rosin.

Now we first stick the cleaned soldering iron tip into the rosin and then poke it into the soldering points of the microcircuit pins. As a result, slowly, bit by bit, the solder begins to transfer from the mounting pad to the soldering iron tip.

We, as it were, tin the soldering iron tip, but only take the solder from the terminals of the desired microcircuit.

So you need to do a large number of iterations, not forgetting to clean the soldering iron tip each time, until the microcircuit is released from the mounting captivity. It is very important here not to get carried away and not overheat the microcircuit. Also, mounting nickels and tracks can fly off due to overheating, but this is important in the sense that you don’t really need the microcircuit itself, but you do need the board itself.

Removing the chip using a razor blade

The main problem with desoldering microcircuits is, as I already said, that while you are heating one terminal, the other has already cooled down, and in order to remove the microcircuit, all terminals must remain heated at the same time. It’s difficult to do this with a soldering iron, but it’s possible.

You can, of course, barbarically bend the tip of some EPSN soldering iron and use a kind of L-shaped hook to heat up the soldering. Or you can go simpler.

Only in this case you need to use some kind of metal plate or bracket that is not tinned.

A razor blade can be used as such a plate. The blade is needed so that the heat from the soldering iron is concentrated not on one terminal, but is transferred to several at once. The only thing is that a more powerful soldering iron may be required, since at low power the heat that was enough for one pin may not be enough for a whole bunch of leads.

Therefore, we press the blade against a whole row of legs of the microcircuit and begin to warm up all the solders at the same time. We warm up and at the same time rock the microcircuit, you can slip a knife blade under the belly of the microcircuit, trying to lift the microcircuit from one edge. Thus, having freed one row of legs from the mounting captivity, in the same way, we free the second row.

Using dismantling braid

When dismantling microcircuits with a bare soldering iron, the ability of the soldering iron to attract solder is used. A soldering iron tip that is tinned and coated with flux has good wettability and absorbs solder very well. But how can we make this process more efficient?

You can, of course, choose a soldering iron with a wider tip, then it will be possible to remove a larger amount of solder. But you can go the other way, you can use the braid from a coaxial cable. The antenna wire from the TV will do. We tear off this braid from the cable and generously cover it with flux.

Now, if you press such a pigtail to the solders of the microcircuit and walk over it a little with a soldering iron, you can be convinced of the wonderful dismantling properties of the braid. Due to its porosity and hygroscopicity, it absorbs solder much better than any soldering iron tip, thereby freeing the microcircuit terminals.

Nowadays there are special dismantling braids on sale, so you can leave the TV wire alone.

Dismantling microcircuits using a desoldering pump

What do you think will happen if you combine an enema and soldering? You will get something shown in the figure. This is a tin pump and this construct was described in an old magazine, either “Modeler-Constructor” or “Radio Magazine”, I don’t remember.

Now they can look completely different, they can be like in the picture, they can be a modified syringe. But this does not change their essence: the soldering iron heats up the junction and the enema bulb or syringe draws out all the solder.

In principle, a very effective dismantling method.

Using medical needles

In general, the point is as follows. At the pharmacy we buy a needle thin enough to fit into the mounting hole and thick enough to be placed on the terminal of the soldered microcircuit.

Using a file, we file the tip of the needle to make a simple hollow tube; it will be even better if the hole is flared a little. It turned out to be a good dismantling needle

And it’s very easy to work with her. We put our tube on the output of the microcircuit, and use a soldering iron to heat the junction. Now, while the solder is still in liquid form, we insert a needle into the mounting hole and begin to frantically rotate the needle until the solder hardens. By placing a needle on the pin, we thereby isolated the leg of the microcircuit from the solder. The needle has a special coating that impairs the wettability of the solder, so the solder does not stick to the needle.

Now, by the way, there are special dismantling tubes of various diameters on sale, so honey. You don’t have to buy needles anymore.

Use of alloy rose

To dismantle microcircuits, you can use rose alloy or wood alloy. A distinctive feature is that these alloys have a low melting point, less than 100 degrees.

To dismantle, pour a few granules into the joint. Now our task is to organize a puddle of alloy by distributing it over all the legs of the microcircuit. This allowed the low temperature alloy to mix with the solder alloy, resulting in a lower overall melting point. The thermal conductivity of the alloy is sufficient and a puddle of alloy covers all the legs of the microcircuit and melts everything. As a result, the chip is simply removed from the mounting holes.

Well, somehow that’s all I have for today.

I think that the article will be useful especially for beginners and will save several nerve cells when dismantling the next microcircuit.

Well, friends, don’t forget to subscribe to blog updates, and I wish you a sunny spring mood, good luck and success!

Soldering microcircuits with your own hands - How to choose a soldering iron

The failure of household appliances is often associated with the failure of a microcircuit (chip). In order not to overpay for expensive repairs at a service center, a burnt-out chip can almost always be replaced at home.

To do this, you need a soldering iron for microcircuits - an installation tool that is used to desolder a failed chip and micro-solder the leads of a new microcircuit to the contact pads of a printed circuit board.

Soldering microcircuits with your own hands is much easier than it seems, the main thing is to choose a good soldering iron.

Soldering iron for microcircuits - how to choose the right one

All electric soldering irons that can be found in a store or on the Internet differ in their characteristics. To answer the question of how to choose a soldering iron for soldering microcircuits, you need to determine its main parameters:

· Power. For micro-soldering of microcircuit pins, it is enough to choose a soldering iron with a power of 20 to 35 W. More powerful soldering irons may cause components to overheat.
· Dimensions and weight. The best thing is a small soldering iron that fits comfortably in your hand. The soldering iron is always held in the fingers, like a ballpoint pen, so it should be miniature and light. You should not buy massive soldering irons with wooden handles - they cannot be properly grasped in your hand. It is not recommended to purchase pistol-shaped soldering irons - they are difficult to solder parts on printed circuit boards.
· Design. When choosing, you need to pay attention to the material of the handle (it should be comfortable, non-slip, and not rub calluses), the design of the electrical cord (the cable must be double insulated, with a wire cross-section of at least 2.5 mm, elastic so that it does not interfere when working).
· Availability of a temperature controller (thermostat). To ensure high-quality soldering, the temperature of the soldering iron tip should be from 260 to 300 °C, not higher. If there is no built-in controller, it is better to choose a soldering iron with a power supply of 12 V or 36 V. According to reviews from radio amateurs, Taiwanese 220 V soldering irons are the worst at controlling temperature - they overheat, which is why it is not possible to solder the microcircuit properly. As a way out, the soldering iron is turned on through a power regulator, which you can purchase or make yourself.
· Shape and type of sting. The best choice is a soldering iron with interchangeable tips. For soldering planar microcircuits, a tip with a diameter of 2 mm with a cut of 45° is best suited, which is convenient for soldering legs with “wave solder”. Thin conical nozzles are convenient for soldering microcircuits with pin terminals in metallized holes on the board. Soldering tips must have a special coating that prevents the appearance of carbon deposits. You should not use ordinary copper attachments - they quickly burn, oxidize, and need to be cleaned periodically.
· Availability of a soldering station. A soldering station is a separate unit with a controller and temperature regulator, to which a soldering iron and other elements (hair dryer, thermal tweezers) are connected via a connector. The station is used mainly for professional or permanent soldering work; for one-time repairs at home, its cost is too high (from 3 thousand rubles).

THIS IS INTERESTING: How to check a weld seam

Source: https://moy-instrument.ru/chertezhi-i-shemy/kak-pravilno-vypayat-mikroshemu-payalnikom.html

All about microcracks in soldering on printed circuit boards

Hello, friends! Today I will try to tell you almost everything about microcracks in soldering on printed circuit boards. I will not talk here about microcracks in microcircuits, cracks in the compound, in conductive paths, in resistors, capacitors and inductors, transformer cores and quartz resonators. All these are topics for separate articles.

And in this material you can read about what microcracks in soldering look like, why they form, how malfunctions from microcracks manifest themselves, why they are dangerous and how to fix them.

What do microcracks look like in soldering on printed circuit boards?

Microcracks in the soldering around the terminals of radio elements when mounted in a hole are very clearly visible even with the naked eye. Peeling of tracks from the board is also often visible.

Microcracks in the solder around planar radioelements for surface mounting are most often visible under magnification through a microscope at a certain angle of light reflection.

Microcracks in the soldering contacts of BGA microcircuits are not visible even with a microscope. Sometimes they can be seen using a microprobe with a light. The microprobe is a light guide with a lens at the end. It is placed in the gap between the board and the microcircuit.

Watch a video about visual soldering quality control systems:

Why do microcracks form in soldering?

Microcracks around contacts mounted in a hole most often appear at contacts of massive elements (transformers, capacitors, chokes) due to board vibrations, even with high-quality soldering. Cracks often appear around the contacts of power connectors when force is applied to them. For example, frequent malfunctions of flash drives are associated with mechanical stress on the USB connector - over time, the contacts of the connectors peel off or even come off.

Microcracks in the solder on the contacts of SMD components appear from the same vibrations and thermal stresses. Also common causes are defects in soldering - cavities in the thickness of the solder, impurities, cold soldering, sagging, overheating, rapid cooling.

Microcracks in BGA ball contacts appear due to soldering defects - cold soldering, poor wettability of contact surfaces, rapid cooling, displacement during cooling, thermal stress.

Look how boards are soldered in China:

How malfunctions manifest themselves if there are microcracks in the soldering

Microcracks in soldering lead to chattering in contacts, changes in load current, loss or appearance of contact when the device heats up during operation. All this most often damages switching power supplies. They are afraid of sudden voltage drops in high-current circuits.

It happens that the soldering area with a microcrack gets very hot due to the small cross-section of the conductor. In this case, the board begins to turn black and charred, carbon deposits appear, which, as you know, conduct electricity. This is a direct path to failure of the power source and high-voltage circuits.

What are the dangers of microcracks in soldering in working devices?

The most dangerous thing about microcracks is sparking and air breakdown in working electronics. All this is accompanied by flammable sparks, loud bangs, acrid smoke, heating and melting of plastic. This is dangerous for humans.

For an electronic circuit, this is dangerous due to the failure of power transistors, expensive processors and burnout of board tracks. In general, this is not very pleasant and leads to expensive repairs. The photo shows soldering defects in the SMD component (resistor) and inhomogeneities in the BGA balls.

How to fix microcracks in soldering

Fixing microcracks in solder is most often very easy - you need to carry out high-quality soldering with a good flux.

Contacts of DIP packages of microcircuits and terminals of radio components can be soldered with solid, gel or liquid flux. In any case, it wets the surfaces being soldered and promotes the spreading of solder. It also removes impurities and air from cavities to the surface of the solder. After soldering, it is better to wash off the flux.

Many soldering defects of SMD components can be eliminated quickly and easily. It is better to solder the contacts of SMD elements with gel or liquid flux, avoiding the formation of excess solder accumulation. Liquid or gel flux is easier to wash off after soldering.

Defects in the contacts of BGA microcircuits are very difficult to correct without removing the microcircuits from the board. There is a well-known popular method of frying and shaking microchips with gel or liquid flux. However, this procedure does not help for long. The fact is that impurities and air cannot escape from the cavities in the solder due to the surface tension forces that exist in the solder balls. Even taking into account the increase in fluidity due to flux.

Therefore, experienced craftsmen recommend removing microcircuits, removing defective solder balls and forming new balls. After preparing the contacts for soldering, installation is best done on an infrared soldering station in compliance with the thermal profile.

See how professional soldering is done:

I’ll wrap it up here - please ask questions about microcracks and the electronic defects they cause in the comments or on the forum.

Master Soldering is with you.

Source: https://masterpaiki.ru/vse-pro-mikrotreshhinyi-v-payke-na-pechatnyih-platah.html

How to desolder a microcircuit

admin Vladimir | 11-02-2016

Category: Tips just in case

everything for soldering, simple tips

Hi all. Very often, beginning radio amateurs are faced with the problem of dismantling microcircuits in a DIP package. Today I will tell you about the easiest way to desolder a microcircuit from a board with a soldering iron. As you know, most radio components: capacitors, resistors, diodes, transistors, have several legs.

As a rule, there are no problems with dismantling these radio elements. By heating each leg in turn, a radio amateur can easily remove the desired radio component from the board.

Things are much more complicated with the desoldering of elements that contain a large number of legs, such as chokes, transformers, various types of filters, and especially microcircuits.

Such multi-pin elements can be removed from the board in several ways, namely three. You can use various types of desoldering pumps, separate or combined with a soldering iron:

This method is the most effective, but not every radio amateur may have a destin pump, especially a beginner.

Do not forget another very good method, namely the use of braid from a shielded cable. Its essence is as follows. We heat the soldering area with a soldering iron through the braid. The tin heats up and is absorbed into this braid, thereby being removed, freeing the output leg of the radio component.

There is a third way to dismantle many output radio components. In terms of efficiency, it is not inferior to a desoldering pump. In terms of price-quality, it even wins, since it costs a penny. Today we will talk about a medical needle. So, we need a syringe needle:

The inner diameter of the needle must be selected so that it can fit tightly onto the pin of the microcircuit. Using a file, you need to grind off the sharp edge of the needle to make it flat and slightly pointed. To make it easier to use, you can lengthen the opposite edge of the needle, thus making a handle.

soldering iron

Let's say we need to unsolder some microcircuit from the board. Let's use a regular soldering iron and our modified needle. The donor will be a board from an old tape recorder:

Using a soldering iron connected through a temperature regulator, you need to heat the pin of the microcircuit and quickly place the tip of a needle on this pin so that it falls inside the printing chamber and immediately pull it out. Then the same operation should be performed for the next pin of the microcircuit. Since the needle is made of stainless steel, it does not have time to be soldered:

If you get the hang of it, the dismantling speed is quite impressive; soldering each pin will take no more than two seconds:

Using this method, I managed to desolder a large number of microcircuits:

This method is good because the microcircuit practically does not overheat, since the contact time of the soldering iron with the terminal is very short. Also, the holes turn out to be very smooth, cleared of tin, and the place is ready for installing a new microcircuit. Which is very important when repairing any radio equipment. Using this method, you can solder chips of various sizes:

The Soviet video recorder Elektronika VM-12 was also disassembled:

Therefore, the same principle can be used to solder not only various microcircuits, but also other multi-pin electronic components, for example TVS transformers. You just need to stock up on needles, the diameter of which will correspond to the specific pin. You can purchase them at the veterinary pharmacy:

I've been using this method for a long time, I really like it. I recommend it to all beginning radio amateurs. For clarity, I even recorded a video:

I will conclude here. I hope that someone has gained new knowledge.

Source: http://radiobezdna.ru/sovety-na-vsyakij-sluchaj/kak-vypayat-mikrosxemu.html

Learning how to safely desolder radio components from boards

When some equipment breaks down, it is not at all necessary to immediately throw it in the trash. If you are interested in electronics and radio engineering, it would be wiser to solder the working elements of the microcircuit. Suddenly, in the future you will need a capacitor, transistor or resistor if you decide to make a homemade electronic product. In this article we will tell you how to desolder radio components from the board so as not to damage anything.

What do you need for this?

There are many devices for soldering parts. Of course, a radio amateur cannot do without a soldering iron, which will be the main assistant in this matter. However, in addition to the soldering iron, in order to desolder the element, you will need:

Tweezers. To remove heated radio components. Instead of tweezers, you can use an alligator clip (shown in the photo below). The advantage of the clamp is that it will securely grip the part and also become a good heat sink.
Hollow needles for dismantling. Buying them will not be a problem, the cost is low. Using needles, you can desolder a radio component quickly and accurately, which we will discuss below.
Dismantling braid. It serves as a so-called sponge that absorbs molten solder into itself, thereby cleaning the board.
Destination pump. The name speaks for itself. An indispensable item for frequent desoldering of radio components from boards at home.

You also need to prepare your workplace. It should be with good lighting. It is best if the lamp is located above the workplace so that the light falls vertically without creating shadows.

Dismantling techniques

So, first we will talk about the most popular technology - how to desolder a part from a board with a soldering iron without additional equipment. After which we will briefly consider simpler methods.

If you want to remove an electrolytic capacitor, just grab it with tweezers (or an alligator clip), heat the 2 terminals and quickly but carefully remove them from the board.

The situation is exactly the same with transistors. Apply solder to all 3 pins and remove the radio component from the board.

As for resistors, diodes and non-polar capacitors, very often their legs are bent during soldering from the back side of the board, which makes it difficult to solder without additional devices. In this case, it is recommended to first heat one terminal and, using a crocodile clip, with a little effort, pull part of the part out of the circuit (the leg should straighten). Then we perform a similar procedure with the second output.

We examined this technique when there is nothing at hand except a soldering iron.

But if you purchased a set of needles, then it will be even easier to desolder the element: first, heat up the contact with a soldering iron, then place a needle of a suitable diameter on the pin (it should go through the hole in the microcircuit) and wait until the solder cools down.

After this, we take out the needle and get a bare lead, which can be easily removed. If the radio component has several legs, we proceed in the same way - warm up the contact, put on the needles, wait and remove.

You can clearly see everything that we talked about in this article in the video, which provides the technology for desoldering elements from the board:

By the way, instead of special needles, you can even use ordinary ones that come with a syringe. However, in this case, you initially need to sharpen the end of the needle so that it is at a right angle.

Desoldering the part using a desoldering braid is also not difficult. Before starting work, wet the end of the winding with alcohol-rosin flux. After this, apply the braid at the desoldering site (on the solder) and heat it with a soldering iron tip. As a result, the heated solder should be absorbed into the braiding, which will free the terminals of the radio components.

With a desoldering pump, things are similar - the spring is charged, the contact is heated, after which the tip is brought to the molten solder and the button is pressed. A vacuum is created, which draws the solder into the desoldering pump.

That's all I wanted to tell you about how to desolder radio components from a board at home. We hope that the provided techniques and video lessons were useful and interesting for you. Finally, I would like to note that you can desolder the elements from the microcircuit with a hair dryer, but we do not recommend doing this. A hair dryer can damage nearby parts, as well as the parts you want to remove!

Interesting on the topic:

Source: https://samelectrik.ru/uchimsya-bezopasno-vypaivat-radiodetali-iz-plat.html