Induction Soldering Stations

Induction soldering stations are contact type stations. The principle of operation of an induction soldering iron was described in the article "Electric soldering irons: types and designs". In short, the principle of operation of an induction soldering iron is as follows.

The soldering rod has a ferromagnetic coating, an induction coil is wound around the rod. High-frequency rectangular oscillations (470 KHz) are fed into the coil, which create eddy currents, Foucault currents in the ferromagnetic coating. Due to losses in the ferromagnet, it is heated, which continues until the temperature reaches the Curie point, at which the magnetic properties of the ferromagnet disappear, and heating ceases.

All induction soldering stations work on this principle, except perhaps with the exception of Chinese ones, which will be discussed later. The method itself is called Smart Heat, which can be translated as “smart heat”. The inventor of this method is the American company Metcal, and it is still one of the main manufacturers of induction soldering stations.

Induction soldering irons are improving

Soldering Station MX-5000

The frequency of 470KHz is currently considered to be reduced, since the best, most advanced, induction soldering stations have a generator frequency of as much as 13 + MHz! A striking example of such a station is the top-level soldering system METCAL MX-5000. Its appearance is shown in Figure 1.

Figure 1. Induction soldering station MX-5000

Such a high frequency allows not only to reduce the size of the soldering tool, which can be estimated from Figure 1, but also to improve its operational properties. The MX-5000 station has a second channel, which is used to connect thermal tweezers, which greatly expands the station's capabilities.

The dimensions of the soldering iron tip are so small that the question may arise, but how is the heat stored in it? After all, it is enough to touch the place of soldering with such a miniature sting, as it immediately cools down. It turns out that everything is somewhat different from ordinary soldering irons.

The tip of the induction soldering iron hardly stores heat, the mass is too small, and cools down when the soldering point is touched. But stabilization on the Curie point is triggered, and the sting itself and the soldering place quickly heat up. The power of the soldering iron is self-adjusting, the power display is shown on the information panel shown in Figure 2. It should also be noted that there are no knobs and buttons on the front panel for setting the temperature, everything happens automatically at the Curie point.

Figure 2. MX-5000 Soldering Station Display

When the soldering rod cools below the Curie point, the magnetic properties are restored, and in proportion to the temperature difference. The larger this difference, the stronger the heating rate, and vice versa, the smaller the difference, the slower the heating, the power is automatically adjusted.

This algorithm is very reminiscent of PID controller operationThe tip temperature is maintained very accurately. After all, the Curie point is a physical law, and you won’t go against the law. If you need a different soldering temperature, you have to use a sting with a different Curie point. In confirmation of these words, you can bring a picture with the technical characteristics of the MX-5000 station.

Figure 3. Technical characteristics of the MX-5000 station

To the working temperature, the induction soldering iron warms up in just 1 ... 2 seconds, which allows you to turn it off when it is just on the stand: they did not have time to bring the soldering iron to the soldering point, but it is already hot! This ensures not only energy savings, but also a significant increase in the service life of the solder rod.

If the first models of induction soldering irons used a soldering rod placed in a cartridge, now separate replaceable tips are used, the number of which is simply huge. A set of interchangeable tips is shown in Figure 4.

Figure 4. A set of replacement tips for the MX-5000

Naturally, these stings are not simple, but with a Curie point. There are several sets of stings with different temperatures: 500, 600, 700 and 800 on the Fahrenheit scale (or 260, 315, 352 and 370 соответственноC, respectively). These temperatures depend on the chemical composition of the soldering rod, from the alloy from which it is made.

The Curie point for iron is 700 ˚C, for nickel 358 ˚C. None of these temperatures is suitable for soldering, so rare-earth elements are added to the alloy, capable of lowering the Curie point of the resulting alloy by any amount. For example, in the rare-earth element gadolinium, the Curie point has a temperature of only 16 ˚C.

The story about this soldering station will be completely incomplete if it is not supplemented by another drawing.

Figure 5. Dream Soldering Station ...

Comments, as they say, are unnecessary. Only the Pentagon could afford such soldering stations, because for the American military, the reliability of electronics is above all.

Chinese induction stations

The Chinese ripened here too. Good and relatively inexpensive induction soldering stations are produced by the Chinese company Quick. But, unlike METCAL, Chinese engineers went their own way. They did not begin to cook alloys with a Curie point, they simply made an induction heater, and they ordered the stabilization of temperature thermocouple electronic unitas in conventional soldering stations. One of the Chinese induction stations is shown in Figure 6.

Figure 6. Quick-203 Soldering Station

As a result of this development, it was possible to obtain ultrafast heating with temperature stabilization, while the price of the device became much lower than that of METCAL stations, perhaps with a slight decrease in quality. But at present, it is Chinese induction soldering stations that are widely used by various companies in their production lines, for example, at RIGOL.

Quick induction soldering stations of the company are gradually gaining popularity among electronic lovers, because it is no accident that Quick-203 model stations are already available in online stores for less than eight thousand rubles. It is thought that those who are constantly engaged in the repair of modern electronics made using Lead Free technology will appreciate all the capabilities of these soldering stations.

Boris Aladyshkin