The quality of soldered joints is, to a very large extends, dependent on a stable process and on the reproducibility of the process parameters. To assure that these requirements are met, modern soldering systems (Reflow, Wace and Selective Systems) incorporate microprocessors and PC's to control and monitor the process. In this way it is possible to store the correct process parameters, once they are established, and call these up again when required. The controls set up the system as required, and subsequently monitor the settings during the production cycle. Should one of the pre-determined tolerances be exceeded, error messages are generated and the production is stopped. This avoids producing defective products.