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Tin bead spatter during soldering? How to effectively reduce it?

2017-05-01 08:38

The DIP post-soldering process can be roughly divided into three types: manual soldering, automatic soldering station welding (semi-automatic), and automatic soldering machine welding. I believe that everyone may have experienced tin bead splashing (tin explosion) during the post-soldering process. This article mainly introduces the causes of tin bead spatter during DIP post-soldering and the methods to effectively reduce tin bead spatter.


1. Causes of tin bead splashing

What is the phenomenon of tin bead splashing (exploding tin and tin explosion)? It means that when the solder wire touches the high-temperature soldering iron tip during the welding operation, some bright solid metal pops up, and a popping sound will be produced. This is the phenomenon of tin bead splashing. The main reason for this phenomenon is due to the structure of the tin wire. Only by realizing this can we really solve the problem. The structure of the tin wire is that the tin is on the outer layer and the inner layer is hollow (like a water pipe). The middle of the wire is filled with flux (rosin). When soldering, once the solder wire touches the high-temperature soldering iron tip instantly, the flux (rosin) inside will melt rapidly at high temperature, producing a large number of bubbles and expanding rapidly, because the tin wire pipe is sealed Yes, a large number of bubbles generated cause high pressure. When the internal pressure is greater than the withstand pressure of the tube wall, the melted tin will be blown away, thus forming a tin explosion. 2. Three types of welding in the DIP post-welding process and methods to effectively reduce tin bead spatter

1. Before manual welding, use an automatic tin breaking machine to break the tin wire in advance before using it. The principle is to use a specially designed round tin breaking blade to punch small holes on the tin wire when the tin breaking machine automatically sends out the tin wire, so that the flux (rosin) inside will be generated when the soldering iron is heated. Vaporization phenomenon, which will seep out part of the solder wire before it melts, thereby reducing tin bead spatter. However, try to use up the solder wire after breaking the tin within 24 hours, otherwise the activity of the solder wire will be greatly reduced, which will affect the welding effect. 2. The automatic tin-feeding soldering station is divided into two types: ordinary type and tin-breaking type: the principle of the tin-breaking type automatic tin-feeding soldering station is exactly the same as that of the tin breaking machine, and it also uses a specially designed circular breaker when automatically sending out the solder wire. The tin blade makes small holes on the tin wire, so that the flux inside will melt when the molten iron is heated during soldering, and part of it will seep out before the tin wire melts, thereby reducing the splash of tin beads.

3. There are mainly the following methods for automatic soldering machines to reduce tin bead splashing: 1. Correct selection of process parameters

(1) When welding current and arc voltage CO2 welding, the spatter rate is small in the short circuit transition, the spatter rate is also small in the fine droplet transition, and the spatter rate is the largest in the mixed transition. When selecting the welding current, attention should be paid to the arc voltage should match the welding current.

(2) The protruding length of the tin wire. Generally, the longer the tin wire protrudes, the higher the splash rate. The protruding length of the tin wire should be shortened as much as possible without clogging the nozzle.

(3) Welding torch angle The amount of spatter is the least when the torch is vertical, and the larger the angle of inclination, the more spatter. It is best not to tilt the torch forward or backward by more than 20°. 2. Use tin wire with low spatter rate

(1) Ultra-low carbon tin wire In the CO2 welding of short-circuit transition or fine drop transition, ultra-low carbon alloy steel tin wire can reduce the spatter caused by CO gas.

(2) The flux-cored tin wire is covered with molten slag on the surface of the molten droplet and the molten pool, and there is an arc-stabilizing agent in the core composition, so the arc is stable and there is less spatter. Usually the spatter rate of flux-cored tin wire CO2 welding is about 1/3 of that of solid wire.

(3) Activation-treated tin wire is coated with a very thin activation coating on the surface of the tin wire, such as a mixture of CS2C03 and K2C03, using DC positive welding, and a compound of rare earth metal or night earth metal can improve the electron emission of the wire metal ability, thereby improving the characteristics of the CO2 arc, so that spatter is greatly reduced. However, due to the difficulty in storage and use of this kind of tin wire, it is not widely used.

3. Adopt tin wire preheating device: preheat the tin wire at about 100 ℃ in advance during the tin feeding process, and then send it to the front end of the melting iron head for welding products, which can reduce the sharp change of temperature during welding, thereby reducing Tin bead splash effect. However, due to the relatively large size of the tin wire preheating device, it has certain limitations in the field use of the equipment, so this method of tin feeding is rarely used on automatic soldering machines.

4. The tin-breaking type precision tin feeding system uses a specially designed circular tin-breaking blade to punch small holes on the tin wire while automatically feeding tin, so that the flux inside will appear when the molten iron is heated. Gasification phenomenon, and then seep out a part before the tin wire melts, so as to achieve the purpose of reducing the splash of tin beads. This method is currently the most widely used mainstream technology in the market.

The splashing of tin beads in the DIP post-soldering process cannot be completely eliminated. We can only take some effective measures to reduce the spattering rate.

The company mainly produces and operates solder paste, solder bars, solder wire, anode plates (rods), anode balls and other related electronic welding materials.

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Hong Kong Chengxing Group Co., Ltd.

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Gaoxin Tin Industry (Huizhou) Co., Ltd.

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Huizhou Chengli Industrial Co., Ltd.

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