Wave soldering

Wave soldering is the traditional mounting method for all push-through components on the PCB. The conditions of the wave soldering process have, however, been redefined due to lead-free procedures. This includes the equipment, the auxiliary soldering material, the PCBs, and the components. Revised standards also require the revision of existing component qualifications.

The market requires that the performance of components be rechecked and confirmed. The aim of this qualification is to achieve flawless soldering quality for components under practical conditions without harmful side effects. At the same time, it must be possible to document the process as well as the scope of performance of the components and auxiliary materials according to the updated standards, whose limits must be observed.

Standards

The qualification profiles described in the standards refer to limit profiles. These are used to qualify the component; the requirements specified here are therefore always more demanding than the real conditions experienced in practice. PCB connection elements must usually be processed in accordance with:

• DIN EN 61760-1: Surface mounting technology
• Standard method for the specification of surface mounting components (SMDs)
• International version: IEC 61760-1: SURFACE MOUNTING TECHNOLOGY Standard method for the specification of surface mounting components (SMDs)

Profile description

According to the profile, the maximum load on a solder pin is 260°C for 10 s in a double wave arrangement, however, it does not go into further detail regarding the geometrical conditions of the assembly. The heat input on the test object at a bath temperature of 260°C and 10 s depends on various factors, such as the thickness of the PCB, the number of layers, and the Cu content of the layers.

The area of application of the standards relates to SMD components; "push-through components" can thus be specified only in accordance with these standards. However, the main advantage of these standards is that an adequate description of a wave soldering profile is provided, as used in standard modern soldering machines. This can also be used as a basis. In addition, PCB connection components must be soldered to SMD components, so that compliance with the requirements can be transferred.

Practical implementation and recommendations

In practice, one would always try to solder at the lower limit of thermal loads. Solder bath temperatures are usually set to 265°C, however, for 95% of applications the maximum contact temperature and solder time are far below the values specified in the maximum profile above.

Below are two recommendations for practical profiles, which are used to qualify PCB connection elements from Phoenix Contact:

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