Selective soldering is a highly specialized process in electronics production that aims to connect specific components on printed circuit boards precisely and reliably. In contrast to conventional wave soldering, in which the entire PCB is immersed in a solder wave, selective soldering only involves soldering at selected points on the PCB. This enables targeted and controlled soldering without affecting other components.

Why is selective soldering necessary?

Selective soldering replaces manual soldering of components on printed circuit boards and offers numerous advantages over conventional soldering processes. It is particularly necessary when SMD boards are fitted with components on both sides or THT parts are arranged in such a way that they cannot be soldered in any other way. In addition, selective soldering enables the soldering of sensitive components that must not be exposed to a wave soldering process due to their low thermal stability.
 

Advantages of selective soldering:

• Precise and individual solder joints: Individual solder joints can be defined per component thanks to precise control via software. This ensures a consistent and reliable soldered connection without damaging neighboring components.
• Protection of sensitive components: Selective soldering reduces the heat load on the assembly, especially for sensitive components such as SMD components and plastic housings. This minimizes the risk of damage during the soldering process and increases the reliability of the assembly.
• No solder masks required: In contrast to wave soldering, no solder masks are required for selective soldering, which saves time and costs. During wave soldering, solder masks protect the SMD components on the underside of the assembly from being melted and washed away in the solder wave. Dispensing with solder masks is particularly economical for small series and reduces the time required to produce and adapt the masks.
• Flexibility and efficiency: Selective soldering systems enable efficient and flexible production of electronic assemblies, even for very small series and individual requirements. By automating the soldering process, time and costs can be saved while at the same time ensuring high quality and precision.
   

Different selective soldering solutions:

There are different variants of selective soldering, which are used depending on the requirements and conditions in production:

• Selective wave soldering: here, only a small part of the assembly is soldered using a "miniature wave", which is particularly used when many SMD components have already been soldered in a reflow process and only a few THT components need to be soldered.
• Selective soldering using the lift/dip process: This involves using a product-specific multi-nozzle soldering tool to solder several components at the same time.

The selection of the appropriate selective soldering solution depends on various factors such as the assembly configuration, the components to be processed and the production requirements. Selective soldering technology is particularly economical when few components or few individual pins need to be soldered and takes up significantly less space compared to conventional wave soldering systems. As KRIWAN Industrie-Elektronik and with Birkholz Elektronische Geräte as part of KRIWAN Holding, we offer customized solutions and many years of experience in the field of wave and selective soldering to meet even the most demanding requirements of our customers.