The goal of an EMS company is to assure maximum assembling quality by minimum costs. This means minimizing losses on technological lines, minimizing defects and re-work time, optimizing assembling process in order to use minimum proceedings. The challenges are the lead-free technology with its increased temperature - could be up to 260degC when using infrared/convection techniques (IR/C) - and the appearance of circuits on glass or metal core (Copper, Aluminum) with its increased thermal mass. The paper is the result of seeking the optimum solution to assemble electronic components using lead-free technology on these kinds of printed circuits boards. Vapour Phase Soldering (VPS) is an old and forgotten technique especially due to the environment impact and to its low productivity. VPS was brought in front by lead-free technology by some major advantages: - the accurate control of the temperature at the maximum 230degC; - simultaneously, continuously and uniform heating of the surfaces, regardless the shape, color and thermal mass of printed circuit board (PCB), solder paste and components; - the remove of the oxygen or other gas molecules from soldering zone eliminating thus the need of using nitrogen.