What Is a Soldering Iron?

It is an indispensable tool for electronic production and electrical maintenance. The main purpose is to weld components and wires. According to the mechanical structure, it can be divided into internal heating type soldering iron and external heating type soldering iron. According to function, it can be divided into non-tin-absorbing electric soldering iron and tin-absorbing type. Electric soldering irons are divided into high power electric irons and low power electric irons according to different uses.

Chinese name: Electric iron
Foreign name: electric soldering iron

Specific: Essential tools for electronics production and electrical repair
Use: Welding components and wires
Classification: Classified by function, mechanical structure, etc.

Introduction to the structure of electric iron

Electric soldering iron is divided into two types: external heating type and internal heating type:

The external heating type electric iron is composed of a soldering iron head, a soldering iron core, a shell, a wooden handle, a power lead, a plug and the like. Because the soldering iron head is installed inside the soldering iron core, it is called an external heating type soldering iron. A soldering iron core is a key component of an electric soldering iron. It consists of a heating wire wound in parallel on a hollow porcelain tube, the mica sheet in the middle is insulated, and two wires are led out to connect to a 220V AC power source. There are many specifications of externally heated electric irons, 25W, 45W, 75W, 100W are commonly used. The higher the power, the higher the temperature of the tip ^[1] .

The internal heating type soldering iron is composed of a handle, a connecting rod, a spring clip, a soldering iron core, and a soldering iron head. Because the soldering iron core is installed inside the soldering iron head, it generates heat quickly and has a high heat utilization rate. Therefore, it is called an internal heating type soldering iron. The commonly used specifications of the internal heating type soldering iron are 20W and 50W. Due to its high thermal efficiency, a 20W internal heating type soldering iron is equivalent to a 40W external heating type soldering iron. The rear end of the internal heating type soldering iron is hollow, used to be sleeved on the connecting rod, and fixed with spring clips. When the soldering iron head needs to be replaced, the spring clip must be pulled out first, and the front end of the soldering iron head should be clamped with pliers. Pull out slowly, remember not to use too much force, so as not to damage the connecting rod ^[1] .

Electric soldering iron instructions

In mobile phone repair, components on the circuit board are often replaced, an electric soldering iron is required, and the requirements for it are also very high. This is because the components of the mobile phone adopt a surface mount process, the components are small in size, the integration is high, the printed circuit is fine, and the pads are small. If the electric soldering iron is not selected properly, it is easy to cause human failure during the soldering process, such as virtual soldering, short circuit, or even damage to the circuit board, so it is necessary to use a higher-grade electric soldering iron, such as a thermostatic antistatic electric soldering iron. In addition, some large devices, such as shielding shields, use high-power electric soldering irons, so you must also prepare an ordinary thick-headed soldering iron of 60W or more.

How to use electric iron

1. Select a suitable solder, and use a low melting point solder wire for electronic components.

2. Flux, use 25% rosin in 75% alcohol (weight ratio) as flux.

3. The electric soldering iron should be tinned before use. The specific method is: heat the electric soldering iron, just after the solder can be melted, apply flux, and then apply the solder to the soldering iron evenly, so that the soldering iron can be eaten evenly. A layer of tin.

4, soldering method, the pads and component pins are cleaned with fine sandpaper, and coated with flux. Use a soldering iron tip to pick up an appropriate amount of solder and touch the solder joint. After the solder on the solder joint has melted and immersed the component lead, the soldering iron tip is gently lifted up along the component pin to leave the solder joint.

5. The welding time should not be too long, otherwise it is easy to burn the components. If necessary, the pins can be clamped with tweezers to help heat dissipation.

6, the solder joints should be in the shape of a sine wave, the surface should be bright and smooth, no tin thorn, moderate tin volume.

7. After soldering is completed, the residual flux on the circuit board should be cleaned with alcohol to prevent the carbonized flux from affecting the normal operation of the circuit.

8. The integrated circuit should be soldered last. The soldering iron should be reliably grounded, or the residual heat should be used after power off. Or use an integrated circuit socket, solder the socket and plug in the integrated circuit.

9. The electric iron should be placed on the iron frame. ^[2]

Classification of electric iron specifications

Electric soldering iron mechanical structure

External heating type soldering iron

It consists of a soldering iron head, a soldering iron core, a shell, a wooden handle, a power lead, a plug and other parts. Due to branding

Electric soldering iron (8 photos)

The iron head is installed inside the soldering iron core, so it is called an external heating type soldering iron. A soldering iron core is a key component of an electric soldering iron. It consists of a heating wire wound in parallel on a hollow porcelain tube, the mica sheet in the middle is insulated, and two wires are led out to connect to a 220V AC power source. There are many specifications of external heating type soldering irons, 25W, 45W, 75W, 100W are commonly used. The higher the power, the higher the temperature of the tip.

Internal heating type soldering iron

It consists of a handle, a connecting rod, a spring clip, a soldering iron core, and a soldering iron head. Because the soldering iron core is installed inside the soldering iron head, it is called an internal heating type soldering iron. The internal heating type electric iron heats up fast and has high heating efficiency, and its volume is small and the price is cheap. The rear end of the internal heating type soldering iron is hollow and is used to be sleeved on the connecting rod and fixed with a spring clip. It is more convenient to replace the tip. When you need to replace the soldering iron head, you must first withdraw the spring clip, while holding the front end of the soldering iron head with pliers, and slowly pull it out. Remember not to use too much force to avoid damage to the connecting rod. General electronic production uses an internal heating type soldering iron of about 35W. Of course, a 50W external heating type soldering iron can be prepared. Due to its high thermal efficiency, a 20W internal heating type soldering iron is equivalent to about 40W of an external heating type soldering iron. Common internal heat and lead-free long-life internal thermoelectric soldering irons on the market have powers of 20W, 25W, 35W, 50W, etc. Among them, 35W and 50W are the most commonly used.

Electric iron temperature control

Constant temperature electric iron

The temperature-controlled electric soldering iron head is equipped with a temperature controller with a magnet type to control the power-on time to achieve temperature control. That is, when the electric soldering iron is energized, the temperature of the soldering iron rises. When the predetermined temperature is reached, the strong magnet sensor reaches The Curie point disappears, so the magnetic core contacts are disconnected, and then the power supply to the electric iron is stopped; when the temperature is lower than the Curie point of the strong magnet sensor, the strong magnet recovers its magnetism and attracts the core switch The permanent magnet in the switch makes the contacts of the control switch on and continues to supply power to the electric iron. In this way, the purpose of controlling temperature is achieved. There are many types of constant temperature type soldering irons, and the core of the soldering iron generally uses PTC components. This type of soldering iron head can not only keep constant temperature, but also anti-static and anti-induction, and can directly solder CMOS devices. The high-end constant temperature electric soldering iron has an additional control device with a digital display (referred to as digital display) of the temperature of the soldering iron tip, which displays the temperature up to 400 ° C. The soldering iron head has a temperature sensor, and the temperature of the soldering can be manually changed on the controller. If you change the constant temperature point, the tip will soon reach the new set temperature. The cordless electric soldering iron is a new type of constant temperature welding tool. It consists of a cordless electric soldering iron unit and an infrared constant temperature soldering station unit. It can realize the wireless transmission of 220V power to heat. The soldering iron unit has a temperature high and low adjustment knob, which can be continuously adjusted from 160 to 400 ° C, and has a high and low temperature indication. In addition, an automatic constant temperature electronic circuit is also designed, which can be automatically constant temperature according to the use temperature set by the user, with an error range of 3 ° C.

Temperature-regulated electric iron

The temperature-adjustable electric iron is equipped with a power controller, which can change the input power of the power supply when used. The adjustable temperature range is 100 ~ 400 . The maximum power of the temperature-regulating electric iron is 60W, and the matching soldering iron head is a copper-plated iron soldering iron head (commonly known as longevity head).

Double temperature type electric iron

The dual temperature type electric soldering iron has a pistol structure, and a power transfer switch is attached to the electric iron handle. There are two switches: one is 20W; the other is 80W. Just change the position of the switch to change the heat of the soldering iron.

Electric iron function

Soldering iron

An electric soldering iron is a desoldering tool that dissolves the piston type solder sucker and the electric iron into one. It is easy to use, flexible, and has a wide range of applications. The disadvantage of this soldering iron is that only one solder joint can be desoldered at a time. The soldering-type soldering iron has its own power supply, which is suitable for occasions where the entire integrated circuit is disassembled and the speed is not high. The materials used for its suction nozzle, heating tube, and sealing ring determine the durability of the soldering iron tip.

Electric soldering iron mechanism

These two situations will bring great difficulties to the debugging and maintenance of electronic production. These two situations can only be avoided after extensive and careful welding practice.

When soldering circuit boards, be sure to control the time. Too long, the board will be burnt, or the copper foil will fall off. When removing a component from a circuit board, attach an electric soldering iron tip to the solder joint. After the tin on the solder joint is melted, pull out the component. The temperature of the soldering iron has a certain relationship with the volume, shape, length, etc. of the tip. When the volume of the iron tip is relatively large, the holding time is longer. In addition, in order to meet the requirements of different solders, the shape of the soldering iron head is different. Commonly, there are cone, chisel, round bevel and so on.

Use a multimeter ohm scale to measure whether there is an open or short circuit at both ends of the plug, and then use Rx1000 or Rx10000 scale to measure the resistance between the plug and the housing. If the pointer is not moving or the resistance is greater than 2-3M, it can be safely used without leakage. The core of the internal heating type soldering iron is made of a relatively thin nickel-chromium resistance wire wound on a porcelain tube. Its resistance is about 2.5k (20W), and the temperature of the soldering iron is generally about 350 ° C. Because the internal heating type electric iron has the characteristics of fast heating, light weight, low power consumption, small size, and high thermal efficiency, it has been used in general applications.

After the electric soldering iron is connected to the power, it is not hot or not too hot. Check whether the voltage of the power supply is lower than AC210V (normal voltage should be AC220V). If the voltage is too low, it may cause insufficient heat and difficulty in soldering. Oxidation of the electric iron tip or oxidation of the root end of the iron tip to the fastening part of the inner wall of the outer tube. The reason why the neutral line is energized, in a three-phase four-wire power supply system, the neutral line is grounded and has the same potential as the ground. If the neon bulb glows when tested with a stylus, it indicates that the neutral line is charged (there is a potential difference between the neutral line and the ground). An open neutral line, an increase in the neutral resistance of the neutral line, an open circuit in the ground lead, and an earthing of the phase line will cause the neutral line to be charged.

When using the soldering iron, please pay attention to the soldering iron should be grounded. It is best to use a pointed soldering iron. The temperature (260 -300 ) can be appropriately added with some flux materials (rosin, flux). The surface-mounted chip should choose a suitable solder. Wire (0.6-0.8), if possible, use a constant temperature soldering iron, wear an anti-static bracelet during the welding process, pay attention to the direction of the core product, and it should be the same as the silk screen. The internal resistance of the soldering iron core varies according to its power specifications. The resistance of a 25W soldering iron is approximately 2k , the resistance of a 45W soldering iron is approximately 1 k , the resistance of a 75W soldering iron is approximately 0.6 k , and the resistance of a 100W soldering iron is approximately 0.5 k . The soldering iron head is made of copper material. Its function is to store and conduct heat. Its temperature must be much higher than the temperature to be soldered.

Electric soldering iron

Both the internal and external heating type soldering irons can be replaced. You can use a few more iron tips, grind these iron tips into the shape you want, and install whatever you want, which is very convenient. You can use a grinding wheel to grind the iron tip, but you must remove the iron tip from the electric iron during grinding, otherwise the electric iron core may be damaged.

Before using the new soldering iron, use a fine sandpaper to brighten the soldering iron head, heat it with electricity, dip it in rosin, and use the tip of the soldering iron head to contact the solder wire, so that the soldering iron head is evenly coated with tin. This can facilitate soldering and prevent the surface of the iron tip from oxidizing. The old soldering iron head becomes black if it is severely oxidized. The surface oxide can be frustrated with steel to expose the metallic luster, and then tinned again before use. Electric soldering iron should use 220V AC power supply. Pay special attention to safety when using it.

It is best to use a three-pole plug for the electric soldering iron plug. Ground the case properly. Before use, carefully check the power plug and power cord for damage. And check if the tip is loose. When using the soldering iron, do not strike hard. To prevent falling. If there is too much solder on the tip of the iron, wipe it off with a cloth. Don't throw it around to prevent scalding others. During the soldering process, the soldering iron should not be scattered around. When not soldering, it should be placed on a soldering iron stand. Note that the power cord should not be placed on the tip of the soldering iron to prevent accidents caused by scalding the insulation layer. After use, please cut off the power in time and unplug the power plug. After cooling, retract the soldering iron into the tool box.

When soldering, solder and flux are also required. For soldering electronic components, a solder wire with a rosin core is generally used. This solder wire has a low melting point and contains rosin flux, which is extremely convenient to use. A commonly used flux is rosin or rosin (dissolving rosin in alcohol). The use of flux can help remove oxides on the metal surface, facilitate soldering, and protect the tip of the soldering iron. Solder paste can also be used when soldering larger components or wires. However, it is corrosive, and the residue should be removed in time after welding. In order to facilitate the welding operation, needle-nose pliers, partial pliers, tweezers and a knife are often used as auxiliary tools. You should learn to use these tools correctly.

Hold the electric iron with your right hand. Use needle-nose pliers or tweezers to hold components or wires in the left hand. Before soldering, the electric iron should be fully preheated. Need to eat tin on the blade surface of the iron head, that is, bring a certain amount of solder. Hold the tip of the soldering iron tip firmly against the solder joint. The electric soldering iron makes an angle of about 60 ° C with the horizontal plane. This will allow the molten tin to flow from the tip to the solder joint. The time that the soldering iron tip stays at the solder joint is controlled within 2-3 seconds. Lift the tip of the soldering iron. The left hand still holds the component still. After the solder at the solder joint has cooled and solidified, you can release your left hand. Use tweezers to turn the leads to make sure they are not loose. Then use a pair of pliers to cut off the excess leads.

Electric iron practical guide

An electric soldering iron is used to solder electrical components. For convenience, a "soldering wire" is usually used as the flux. The soldering wire generally contains rosin to aid soldering. The solder wire is synthesized using about 60% tin and 40% lead, and has a low melting point.

Rosin is a flux that can help with welding. People who pull erhu must have it. I heard that they can also be purchased at pharmacies. Rosin can be used directly, or it can be configured as a rosin solution, that is, crush the rosin, put it into a small bottle, and then add alcohol to stir. Note that alcohol is volatile. Remember to tighten the cap after use. A small piece of cotton can be placed in the bottle, which is then clamped out with tweezers and applied on the printed board or components.

The electric soldering iron is held in your hand. Be careful when using it. The new electric soldering iron must first check the resistance value between the plug and the metal case with a multimeter resistance file. The pointer of the multimeter should not move. Otherwise it should be thoroughly checked.

In the production of internal heating type electric soldering irons, in order to save costs, manufacturers do not use rubber cords, but use plastic wires directly, which is relatively unsafe. It is highly recommended to use a rubber cord because it is not as susceptible to burns, breakage, or short circuits or electric shocks as plastic wires.

Before using the new electric soldering iron, use a file to file the tip of the soldering iron. The color of the soldering iron will change after you turn on the power, which proves that the soldering iron is hot. Not easily oxidized. In use, keep the tip of the soldering iron clean and ensure that there is always solder on the tip of the soldering iron.

When using a soldering iron, if the temperature of the soldering iron is too low, the solder cannot be melted, or the solder joints are not completely melted and become unsightly and unreliable. Too high will cause the soldering iron to "burn" (despite being tinned, despite the high temperature). In addition, it is also necessary to control the soldering time. The soldering iron stays too short, the solder is not easy to completely melt, and the contact is good, forming a "virtual solder". The soldering time is too long and it is easy to damage the components or the copper foil of the printed circuit board Tilt up

Generally, a solder joint should be welded within one or two seconds. If it is not completed, it is better to wait for a while and then solder again. The electric iron cannot be moved during soldering. You should first select the position that contacts the solder joint, and then use the tinned surface of the soldering iron tip to contact the solder joint.

Introduction:

1. High-performance ceramic heating core, fast heat transfer speed, welding can be performed within one minute.

2. The soldering iron head is slender, which is most suitable for soldering precision circuit boards.

3. The heater uses a single-button connector instead of a small heater and power cord. It is easy to use and has good operability, which is ideal for precision welding.

4. Voltage 220/230 / 240V.

Electric soldering technology

In electronic production, welding of circuits and components is bound to be encountered, and the quality of welding has a great impact on the quality of production. Therefore, to learn electronic manufacturing technology, we must master the welding technology.

Pre-treatment of electric iron

Before soldering, the soldering of component pins or circuit board soldering parts should be performed. Generally, there are three steps: "scraping", "plating" and "testing".

1.Scrape

"Scraping" means cleaning the welding area before welding. Generally used tools are a knife and fine sandpaper to clean the pins of integrated circuits and printed circuit boards, but keep the pins clean. For self-made printed circuit boards, the surface of copper foil should be polished with fine sandpaper, and the dirt on the printed circuit boards should be cleaned, and then coated with rosin alcohol solution, flux or "HP-1" before use. For gold-silver-plated alloy lead-out wires, the plating cannot be scraped off, and the surface contamination can be removed with an eraser.

2.Plating

"Plating" means tinning the scraped components. The specific method is to dip the rosin alcohol solution on the scraped component soldering parts, then press the hot soldering iron head with tin on it, and rotate the components to evenly coat a thin layer of tin. If it is a multi-strand wire, it should be twisted together after being polished, and then tinned.

After the "scratched" component leads should be immediately coated with a small amount of flux, then use a soldering iron to plate a thin layer of tin on the leads to avoid re-oxidation of the surface to improve the solderability of the components.

3.Test

"Testing" means after the "plating", use a multimeter to test whether all tin-plated components are of reliable quality. If there are unreliable or damaged components, they should be replaced with components of the same specification.

Electric soldering technology

After the pre-welding treatment is completed, the welding can be officially performed.

1.Welding method

Different soldering irons require different working temperatures. When judging the temperature of the soldering iron head, you can touch the electric iron to the rosin. If the soldering iron touches the rosin, there is a "squeaking" sound, it means that the temperature is appropriate; if there is no sound, only the rosin can barely melt, it means that the temperature is low ; If the soldering iron tip smokes a lot when it touches rosin, the temperature is too high.

Generally speaking, there are three main welding steps:

First, a small amount of solder and rosin are melted on the soldering iron head, and the soldering iron head and the solder wire are aligned at the solder joints at the same time.

Before the flux on the soldering iron head has evaporated, touch the soldering iron head and the solder wire at the same time to start melting the solder.

After the solder has soaked the entire solder joint, remove the soldering iron head and solder wire at the same time or remove the solder wire first. After the solder joint is full and beautiful, leave the soldering iron head and solder wire.

The welding process is generally 2 to 3 seconds. When soldering integrated circuits, strictly control the amount of solder and flux. In order to avoid damage to the integrated circuit due to poor insulation of the electric soldering iron or induced voltage from the internal heater to the shell, in practice, the method of unplugging the power plug of the electric soldering iron while hot welding is often used.

2.Welding quality

When welding, ensure that each welding point is firmly welded and in good contact. The tin dots should be bright, smooth and without burrs, and the amount of tin should be moderate. Tin and the object to be welded are firmly fused, and there should be no false soldering or false soldering. False soldering means that only a small amount of tin is soldered at the solder joint, resulting in poor contact and continuous interruption. False soldering means that the surface seems to be soldered, but it is not actually soldered. Sometimes the lead can be pulled out of the solder joint when it is pulled by hand.

3. Welding materials

For materials that are not easy to weld, you should use the method of plating first and then welding. For example, for aluminum parts that are not easy to weld, you can plate the surface with copper or silver before welding. The specific method is to first add some CuSO4 (copper sulfate) or AgNO3 (silver nitrate) to a solution with a concentration of about 20% by adding water. Then put the cotton ball with the above solution on the smooth aluminum parts polished with fine sandpaper, or directly immerse the aluminum parts in the solution. Due to the substitution reaction between copper ions or silver ions in the solution and aluminum, a thin layer of metallic copper or silver will precipitate on the surface of the aluminum part after about 20 minutes. Absorb the solution on the aluminum part with a sponge and bake it under the lamp until the surface is completely dry. After completing the above work, apply rosin alcohol solution on it, and you can directly weld.

Note that this method is also applicable to iron parts and some alloys that are not easy to weld. The solution should be covered after use and stored in a cool place. When the solution concentration decreases continuously with the increase of the number of uses, it should be reconstituted. The solution is corrosive and should be avoided as much as possible in contact with the skin or other objects.

Electric soldering iron mechanical maintenance

Selection of electric iron

There are many types and specifications of electric soldering irons, and the sizes of the workpieces to be welded are different. Therefore, the reasonable choice of power and type of electric soldering iron has a direct relationship with improving the quality and efficiency of soldering.

(1) When soldering integrated circuits, transistors, and thermally vulnerable components, a 20W internal heating or 25W external heating type soldering iron should be used.

(2) When soldering wires and coaxial cables, first use a 45W ~ 75W external heating type soldering iron or a 50W internal heating type soldering iron.

(3) When welding large components, such as the lead pins of line output transformers, lead pins of large electrolytic capacitors, ground pads of metal chassis, etc., an electric soldering iron of more than 100W should be used.

The electric soldering iron uses an adjustable constant temperature soldering iron. When the soldering iron is not used, it is necessary to keep a certain amount of tin on the tip of the soldering iron. Do not store the tip on a sponge after cleaning it on a sponge. Measure the amount of water to make the sponge moist all day long. When you pick up the soldering iron and start using it, you need to clean the soldering iron tip, but you do nt need to take the soldering iron tip to the sponge during the use process, just put the tin on the soldering iron tip. Put it in a tin collection box, so that the temperature of the soldering iron tip will not drop sharply. If there is still difficulty in extracting tin on the IC, add some tin up (because the solder wire contains flux), you can easily extract more The tin is down; it is normal for the soldering iron temperature to be between 340 and 380 degrees. If some sensitive components can only accept soldering temperatures of 240 to 280 degrees, the soldering iron has black hair and cannot be treated with metal devices such as blades, but must be used. Rosin or tin wire to solve; after using it every day, clean it first, then add enough tin, and then cut off the power immediately.

Precautions for electric soldering iron

Precautions for using electric iron

1. Before using the electric iron, check whether the voltage used is consistent with the nominal voltage of the electric iron;

2. The electric soldering iron should have a ground wire;

3. After the electric iron is powered on, it cannot be arbitrarily tapped, disassembled and installed.

4. The electric soldering iron should be kept dry and should not be used in an excessively humid or rainy environment;

5. When removing the iron tip, cut off the power;

6. After cutting off the power, it is best to use the residual heat to put a layer of tin on the soldering iron head to protect the soldering iron head;

7. When there is a black oxide layer on the tip of the soldering iron, wipe it off with an emery cloth, then apply power, and immediately apply tin;

8. Sponge is used to collect tin slag and tin beads. It is suitable that the water does not come out by pinching with your hands;

Nine, do "5S" well before welding, and also do "5S" after welding.

Electric iron temperature setting

First, the temperature is determined by actual use. It is most suitable to solder a solder joint for 4 seconds. Observe the tip of the soldering iron normally. When it turns purple, the temperature is set too high.

2. Generally, insert the electronic material directly, set the actual temperature of the soldering iron head to (330 ~ 370 degrees); for surface mount materials (SMC) materials, set the actual temperature of the soldering iron head to (300 ~ 320 degrees).

3. For special materials, you need to set the temperature of the soldering iron.

Fourth, microphones, buzzers, etc. should use silver-containing tin wire, the temperature is generally between 270 degrees to 290 degrees.

Fifth, solder large component feet, the temperature should not exceed 380 degrees, you can only increase the power of the soldering iron.