Dip soldering

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In the case of dip soldering , the workpiece is completely or partially immersed in the liquid solder in a first process in order to heat the pins of the component and the circuit board. For this purpose, the assembly to be soldered is usually located in a receptacle. The inclusion prevents liquid solder from reaching the top of the assembly.

Another option for dip soldering is to move a stamp out of the solder pot for soldering. This stamp has recesses at all points on the assembly that have to be soldered. In these recesses there is liquid solder when lifting, which creates the soldered connection.

Establishing the soldered connection

The heat input for soldering occurs through the liquid solder in the solder pot. In the manufacture of printed circuit boards assembled on one side, this process increased labor productivity compared to labor-intensive soldering using a soldering iron , since all soldering points on the printed circuit board could be soldered simultaneously. Dip soldering was later replaced by wave soldering .

So that the liquid solder does not immediately form slag, the solder pot is placed under a protective atmosphere , e.g. B. nitrogen held. Slag is lighter than liquid solder and floats on the surface in the solder pot. When soldering, slag can influence the soldering process, there is a risk that either no soldered connection is made or that the soldered connection is of poor quality.

Compared to wave soldering systems or selective soldering systems, dip soldering systems are usually of a simpler and more compact design and usually also require significantly less space in production.

Limits

In classic dip soldering, there are often solder bridges between closely spaced pins on the components (e.g. for plugs with a fine grid), which usually have to be removed manually after soldering. In contrast to wave soldering, the assemblies are usually lifted vertically out of the solder bath, so that liquid solder cannot flow away between neighboring pins and forms solder bridges. This method is suitable for soldering when the soldering points are not too close together.

This soldering process is particularly suitable for soldering assemblies that draw little heat from the soldering point. Furthermore, during immersion soldering, the surface tension sucks the liquid solder into the sleeve of the soldered joint. Compared to wave soldering or selective soldering, there is no intrinsic movement of the liquid solder with this method, so that the solder penetration is sometimes not as pronounced as in the two other soldering methods.

Other soldering methods

With the introduction of SMD technology, dip soldering practically no longer played a major role. Wave and drag soldering are very widespread in the electrical industry today . With these two methods, simple SMD components (glued during SMD assembly) can be soldered with an adapted assembly density. However, the use of these standard methods very quickly reaches its limits with a higher assembly density and with components that are more difficult to solder. The rapidly increasing use of soldering systems with double wave brings further improvements.

Practical use

This method is suitable for soldering assemblies in which the distances between the soldering points are not too small, otherwise bridging can occur. Today, dip soldering systems are sometimes still used for tinning component connections or flexible cables.

literature

  • Reinard J. Klein Wassink: Soft soldering in electronics . 2nd Edition. Eugen G. Leuze, Saulgau 1991, ISBN 3-87480-066-0 .
  • Wolfgang Scheel (Hrsg.): Assembly technology of electronics . Verlag Technik et al., Berlin et al. 1997, ISBN 3-341-01100-5 .