Vapour phase soldering (VPS) is a special form of Surface Mount Device (SMD) reflow soldering in which the solder connection is made in a controlled vapour phase. Unlike convection reflow soldering using hot air, it involves soldering in hot vapour. Perfluorinated polyether (PFPE) is used to generate the vapour. The liquid and vapour are electrically non-conductive and safe for health. PFPE fluids come with different boiling points, and depending on the application, the soldering temperature can be defined using the medium. For lead-free soldering, GALDEN LS-230 is typically used, soldering at a maximum of 230°C. As PFPE is chemically inert, the vapour displaces oxygen, allowing soldering in an oxygen-free atmosphere. No residues of the fluid are left on the soldered boards.

The advantages of vapour phase soldering are:

1. Uniform and reliable solder connections: The use of vapour as a heat transfer medium achieves even temperature distribution without thermal shadows, resulting in high-quality and reliable solder connections. This minimizes the risk of cold solder joints or insufficient connections.

2. High reproducibility: Since the soldering process takes place in a controlled environment, the reproducibility of vapour phase soldering is very high.

3. Protection against oxidation: The vapour phase acts as a protective layer and prevents the formation of oxide layers on the components to be soldered. This improves the wetting ability of component surfaces and the quality of the solder connection.

4. Applicability to complex assemblies: Vapour phase soldering allows effective heat transfer to complex assemblies with multiple components, different package sizes, and shapes. This enables reaching difficult solder joints.

5. Gentle soldering: For lead-free soldering, PFPE fluid with a boiling point of 230°C is used. Thus, even in the peak range, a maximum of 230°C is reached – components and the circuit board are soldered gently.

6. Safe soldering: Since relatively low temperatures are needed for soldering, and the maximum temperature is defined by the boiling point of the Galden fluid, overheating cannot occur with proper application.

7. Energy-saving: Compared to other soldering methods, vapour phase soldering is energy-efficient due to lower temperatures and efficient heat transfer.