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DECEMBER 2024 I SMT007 MAGAZINE 23 able heating and cooling ramps) are reproduc- ibly controllable. A minimum of 0.1 mbar can be achieved. e heating plate is designed for temperatures of up to 752°F, which allows the use of higher-melting solders. Condensation Soldering With Vacuum System technology In the condensation soldering system shown in Figure 5, the soldering process takes place in a hermetically sealed process chamber: with the help of the thermally conductive medium, a liquid film builds up that surrounds and vaporizes the entire assembly. e vapor con- denses on the assembly until a soldering tem- perature of 464°F is reached (e.g., when using HS240). Rehm uses a patented injection prin- ciple to better control the condensation phase. Aer the evaporation and heat transfer to the assemblies, the process medium is extracted, cleaned, and reused. e vacuum can be gen- erated in the chamber in any process step. Profiling During soldering with the smart soldering system, the pre-vacuum can be used to remove outgassing released during the heating phase from the process area and prevent contamina- tion or soiling of the surfaces. e main vac- uum is used in the molten state of the solder to reduce the pores. With this system, the vac- uum option is available for the entire duration of the soldering process, allowing very specific process requirements to be met. For example, by injecting the thermally conductive medium into the vacuum, a more even distribution of the gas (vapor) can be achieved, resulting in a more homogeneous temperature distribution over the height of a product. Figure 6 shows an example of how identical temperatures can be achieved over a height of 75 mm using com- bined temperature-pressure profiling. is fea- Figure 5: A smart soldering system. Figure 4: Temperature profile with pre-vacuum and main vacuum from a soldering process.