The process has idle times for detecting the medium type by identifying boiling point temperature (noted as \"medium recognition\"). The cooling can also take a long time, elongating the soldering job. In addition, the use of mid-profile temperature plateaus is not available in HL-VPS ovens. Despite its recent fame, the VPS process can still be improved from many aspects, e.g., in the aforementioned thermocouple-based measurements [8]. Thermocouple application was investigated by [PERSON] et al. [9] and [PERSON] [10], both in experimental ovens, for real-time profiling and control. Before the vapour starts to saturate the available volume above the boiling fluid, non-saturated air-vapour mixture is present in the workspace, which was modelled with FDM in [11]. It is not straightforward to use this non saturated vapour for soldering, but more advanced ovens can take advantage of the vertical concentration gradients inside the tank. Galden vapour concentration and the consequent saturated vapour column is increasing from the bottom due to the boiling. The volumetric mass density of the Galden vapouris 20 times larger than the density of the air. Consequently, even unsaturated vapours (air-Galden mixture) can store a non-negligible amount of energy. Thus, the energy of this mixture can be still enough to heat up temperature sensors monitoring the workspace. The need to measure dynamic concentration changes can be satisfied with pressure-based sensing with tubes. This approach was introduced when sensitive, differential flow-sensor based pressure-measurement was realized in standard VPS ovens. This approach can increase productivity [12] by reducing idle times of the ovens. Dynamic vapour concentration monitoring can provide information on the development of the saturated vapour column. However, in [12], the hydrostatic pressure detection was limited due to the then available apparatus. There is another alternative for vapour height detection for control application. [PERSON] presented a plate capacitor for vapour column height monitoring, which is able to withstand high-temperatures [13; 14]. The change of dielectric properties inside the two plates of the capacitor change as the saturated vapour condenses between the plates. The capacity change can be used to fine-tune the oven controls. However, this solution is still in an experimental phase, and it is not yet available for commercial use. The application of an experimental optical probe is also possible [15], but it is not applicable for continuous use, only with individual dipping into the vapour. Recent application of vapour phase soldering was mostly presented for modern surface mounted PCBAs. The method was investigated for LED and BGA based assemblies [16]. The quality of the joints was also a crucial question in comparison of other reflow methods [17], in the specific field of power electronics [18], airborne electronics [19], or regular surface mounting, with the focus on void failure analysis [20; 21]. Advances in commercial pressure sensors enable unprecedented resolution in ultra-low atmospheric pressure levels with gauge-based sensor cores. Due to the gauge-principles, such sensors are ideal for hydrostatic pressure sensing with fine resolution. The aim and the novelty of this research are to present the application of such sensor type in the control of the heat-level based vapour phase soldering process and to compare pressure-profiles with the traditional thermocouple-based temperature profiles in HL-VPS. The sensor is also used to identify leakage inside the workspace. The proposed method is generally applicable for VPS ovens based on the same principle, and the industry may benefit in various aspects, discussed in the following chapters.