How to choose a soldering station

An ordinary copper soldering iron soldering iron is not very suitable for soldering modern miniature circuit boards with SMD mounting. You can use it, unless, for soldering household appliances and printed circuit boards with output components, as they say, from case to case.

For the installation and repair of modern electronics, soldering stations are increasingly being used, which have gained great popularity both among professional electronic engineers and amateur radio enthusiasts. This article gives a brief overview of soldering stations, which will undoubtedly help to solve the question of which station is better to purchase.

Contact and non-contact soldering stations

All soldering stations can be divided into two large categories mentioned in the header. Contact stations, in fact, are ordinary soldering irons controlled by an electronic unit. Previously, this design was called a soldering iron with a temperature regulator. The soldering technology is the same as a simple soldering iron, which was used by almost all radio amateurs and professional installers.

How to solder a chip?

The miniaturization of electronic components, the emergence of multi-pin circuits have led to the fact that conventional soldering iron it became impossible to solder the microcircuit. Some microcircuits do not have conclusions in the classical sense, for example, microcircuits in BGA cases (from English Ball grid array - an array of balls).

Such microcircuits are installed on the memory modules of personal computers and on motherboards. These modules were seen and held by many users. The appearance of the memory module is shown in Figure 1.

Figure 1. A memory module with microchips in BGA packages

Planar microcircuits also became very multi-output: many of them have one hundred or more legs. It is simply impossible to solder such a chip without ruining the board with a conventional soldering iron. A fragment of a board with a multi-pin microcircuit is shown in Figure 2.

Figure 2. Multiple output planar microcircuit

It was such microcircuits that led to the creation of contactless soldering methods. At first it was heating with hot air using a hot air gun, later devices were created in which heating is carried out by infrared radiation. But let's not rush, we will begin the story with contact soldering stations.

Contact Soldering Stations

They are divided into two large categories. These are stations for soldering with ordinary tin-lead solders and stations for soldering with lead-free solders. As an example of “lead” stations, we can cite stations of several models: Lukey 936+, AOYUE 936, AOYUE 937, Solomon SR-976 ESD.

Figure 3. AOYUE 936 Soldering Station

Figure 4. AOYUE 937 Soldering Station

Figures 3 and 4 show the appearance of the analog soldering stations AOYUE 936, AOYUE 937.

The technical data of both stations are almost identical. Both are equipped with a type 10087 soldering iron with a ceramic heater and an integrated temperature sensor. Complete with a soldering iron there is one conical tip, but, if desired, you can buy a whole set at once, which will expand the range of soldering work.

The power of the soldering iron is 40W with a supply voltage of 24V, which allows soldering elements sensitive to static electricity without fear. In addition to the low supply voltage, the soldering iron tip is grounded. The electronic unit maintains a temperature in the range of 200-480 ˚C with an accuracy of +/- 1 ˚С. The temperature control is stepless, smooth with a single knob on the front panel of the device.

The size of the soldering iron is 190 mm, while the weight is only 55 g, which provides a fairly comfortable user experience. The soldering iron is connected to the electronic unit by a five-pin connector. The kit includes a replacement heating element HAKKO-003 with built-in temperature sensor, stand for a soldering iron and a sponge for cleaning tips.

There are no special operational differences between the stations, except for the fact that the AOYUE 937 soldering station is equipped with a digital indicator of the current and set temperature. This, apparently, allows you to set the desired temperature somewhat more accurately than in the absence of an indicator. But even with a digital indicator, you have to set the temperature on the principle of “a little more, a little less” until the best result is achieved.

Analog and Digital Soldering Stations

According to the control principle, all soldering stations are divided into analog and digital. In analogue stations, temperature stabilization is carried out according to the on / off principle: the set temperature is reached - the heater is turned off. The temperature has dropped, the heater turns on - heating begins. In essence, a conventional electromagnetic relay can control the heater. With this control method, overheating of the soldering iron tip is often possible. The accuracy of maintaining the temperature is low.

In digital soldering stations, temperature is controlled PID controllerimplemented by microcontroller software. If you do not go into details, then the regulation process is the same as that was given a little higher, but the power supplied to the heater changes. If the soldering iron tip has cooled slightly below the set temperature, then the required heating power is small, it still has time to heat up, but it does not “run away” above the set temperature.

When soldering massive parts, the tip cools faster, the difference between the set and current temperature is large. To quickly “catch up” the set temperature, the PID controller proportionally increases the heating power. Naturally, the digital method of maintaining temperature is more accurate than the analog one.

Lead-Free Soldering Stations

They differ from the “lead” stations only in the greater power of the heating element: 75 ... 160W. The fact is that lead-free solders are refractory, the melting point is 300 ˚C (and the quality of these solders, compared to tin-lead ones, leaves much to be desired), and while the soldering place is heated until the solder melts, the tip will have time to cool down to such an extent that even the most a perfect temperature controller will not correct the situation immediately. Therefore, only a sufficiently powerful heater can save the situation.

You don’t need to be afraid of “excessive” power, because even if the power is at least 1000 W, the tip temperature will still not rise above the set point, the soldering iron will never overheat, but the tip heats up very quickly. Thanks to this, thin tracks of printed circuit boards and massive parts such as relays or transformers can be soldered equally well. With the help of “lead-free” stations, you can solder and traditional “lead” solders.

The most common lead-free soldering stations are Goot PX-501, GOOT RX-802AS, AOYUE 2900, GOOT RX-852AS, ATTEN AT80D, GOOT PX-201. The appearance of the ATTEN AT80D soldering station is shown in Figure 5.

Figure 5. ATTEN AT80D Soldering Station

The station is equipped with a soldering iron with a ceramic heater with a power of 80 W, stand for a soldering iron, a sponge for cleaning the tip. The main technical data of the station are shown in Figure 6.

Figure 6. Technical data of the ATTEN AT80 soldering station

What is a hot air gun for?

Contact soldering stations belong to the assembly class: you can solder a part, but it is practically impossible to solder a multi-pin case. For these purposes, there are dismantling soldering stations. The most common stations with hot air gun. Often, radio amateurs use industrial building hair dryers to solder multi-pin components.

Nevertheless, it is possible to achieve the desired result with the help of a building hair dryer, but it often happens that innocent parts fly off the board under a powerful stream of air. To make the consequences of blowing away parts less severe, it is best to first take a photo of the board. Then it will not be necessary to think and wonder where this detail was.

Therefore, instead of a building hair dryer, it is better to purchase a special hair dryer for soldering with hot air. One such hairdryer is shown in Figure 7.

The design, of course, is far from perfect, but for use from case to case it will be almost perfect. One of the positive qualities of such a device is its low price.

If such a price turns out to be unattractive, then a hot air gun can be made independently from improvised materials. The design of a homemade hairdryer can be borrowed on the Internet, since there are plenty of them.

Figure 7. DADI 8032 soldering iron

Three round nozzles of various diameters are included in the package of delivery, which allows changing the width of the hot air stream. The hair dryer has a built-in turbine type fan. At the end of the handle there are two knobs: the lower (according to the figure) handle allows you to adjust the heating temperature, the upper changes the air flow. There is an LED indicator between the handles: the higher the set temperature, the more often the LED flashes.

On the handle side, opposite to the regulators, there is a key switch. When the hair dryer is turned off, the heater first turns off, then, with some delay, the fan turns off. In this way, the hair dryer is partially cooled when turned off.

It is not known what the outlet temperature is, but practice shows what to focus on: on the knobs of the regulators there are scales with numbers: it is quite possible to estimate the degree of heating.

Another option is to simply measure the outlet temperature with thermocoupleswhich some multimeters are equipped with. Hair dryers of this design are produced and more advanced, they have a digital temperature indicator and a thermal stabilization system. But such hairdryers are somewhat more expensive.

Contactless Soldering Stations

Thermoair soldering stations with a separate electronic unit are more advanced. Figure 8 shows the ATTEN 858 D + soldering station.

Figure 8. ATTEN 858 D + Soldering Station

The station kit includes three round nozzles, there is air flow adjustment and digital temperature indication. The temperature is controlled by pressing the red buttons, the heating process is controlled by the red “CAL” LED on the front panel.

The fan for air supply is located in the handle of the hot air gun, so the connecting wires go to the hot air gun, which makes working with a hairdryer quite comfortable compared to compressor hair dryers, where air is supplied through a hose. A rigid hose binds hands and makes manipulation difficult.

Some soldering stations use a compressor located in the control unit to pump air. Then, in addition to the wires, a fairly rigid rubber hose goes to the hairdryer, which somewhat interferes with operation. A similar design is, for example, the Chinese Lukey 852D + soldering station, the technical characteristics of which are shown in Figure 9.

Figure 9. Technical specifications of the Lukey 852D + Hot Air Soldering Station

The delivery set includes an electronic unit, a soldering iron with a stand, a hot air gun and four round nozzles, which allows you to adjust the diameter of the air flow. The hot air gun mounting bracket can be installed on the left or right side of the soldering station, well, it’s convenient for anyone.

The appearance of the station is shown in Figure 10.

Figure 10. Lukey 852D + Soldering Station

Inside the metal case are a transformer, a diaphragm pump and a circuit board with electronic components. Of all the soldering stations of the Lukey family, so popular among hams, this model is the heaviest, its weight is 4 kg. The metal case not only makes the design heavier, but also increases the reliability of the device: in the chaos of a repair shop, a soldering station can go anywhere ...

On the front panel there are two digital temperature indicators: separately for a soldering iron and a hairdryer. Accordingly, there are knobs for setting the temperature and air flow rate. Such a station is called dual channel. There are stations with three channels, for example, Lukey 853.It allows you to turn on the hot air gun and two soldering irons with different nozzles. The appearance of the Lukey 853 soldering station is shown in Figure 11.

Figure 11. Lukey 853 Soldering Station

The hot air guns of Lukey 852D + and Lukey 853 soldering stations are of compressor type: the compressor is inside the case, and air is supplied to the hairdryer through a hose. A number of round nozzles are included. If necessary, you can buy additional nozzles, some of which are shown in Figure 12.

Figure 12. Nozzles for a hot air gun of compressor type

Each nozzle is designed for soldering microcircuits in a particular case. With the help of such nozzles, it is easy enough not only to solder the microcircuit, but also to solder it to the board. In fact, there are much more nozzles than in the picture. Only a few of them are shown here.

Such nozzles are designed specifically for compressor type hair dryers. If the hot air gun has a built-in impeller turbine, then the nozzles are used round, which is equipped with a soldering station. Replaceable nozzles for a fan-type hot air gun do not seem to be available.

Although the main purpose of a soldering hot air gun is to carry out soldering work, its use for other purposes is not at all ruled out. it heat shrink tube, heating hot melt adhesive, bending and welding of plastics and just drying something somewhere.

When soldering with a conventional soldering iron using a hot air gun, you can slightly heat up a portion of the board, which will make the soldering conditions more comfortable - you do not need to spend the heat stored in the tip of the soldering iron to heat the board.

Some stations have a fan built directly into the hot air gun, for example, Lukey-702. It replaced the discontinued Lukey 852D + and Lukey 853 stations. The appearance of the station is shown in Figure 13.

Figure 13. Appearance of Lukey-702 soldering station

The station is microcontrolled, which allows you to remember the previously set temperature. The hairdryer stand has a microswitch: if the hairdryer is placed on the stand, it turns off. Repeated removal from the stand turns on the hairdryer again, so you have to wait for it to warm up, which is not very convenient. To avoid this, experienced users suggest using a separate stand for the hairdryer.

The station has a small size, a plastic case, the weight of the station is not more than 1.5 kilograms. According to user reviews, the station is less noisy than Lukey 852D + and consumes less power. Ideal for cell phone repair. Brief technical specifications of the Lukey-702 soldering station are shown in Figure 14.

Figure 14. Characteristics of Lukey-702 soldering station

For the Lukey-702 station, there is a large set of replaceable tips for the soldering iron, about forty pieces that are shown in the service manual of the Service_manual_Lukey702_rus.pdf station. There are also diagrams of the electronic control unit and station operation algorithms. This manual is not difficult to find on the Internet.

All soldering stations described above have anti-static protection by grounding through the power plug. To do this, the electrical outlet must have a grounding contact.

Now on the market there is such a thing as "good China." It is in this category that the budget stations Lukey and Aoyue belong, deservedly winning the sympathy of radio amateurs and professionals. Their price is in the range of 2000 ... 4000 rubles. As the saying goes, the optimal price / quality ratio.

Figure 15. Aoyue-2702a Soldering Station

In addition to the soldering iron and hot air gun, modern soldering stations are equipped with a dismantling gun (a soldering iron with a suction of solder), as well as a smoke collector that allows you to get more comfortable working conditions - along with lead-free solders, there is also concern for the environment and working conditions. One of these Aoyue-2702a soldering stations is shown in Figure 15.

The price of such a station in online stores is at the level of about 16,000 rubles, which makes it not very affordable for ordinary amateur radio enthusiasts.

Boris Aladyshkin

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