The DarkSide-20k experiment aims to the direct WIMP detection in extremely low background conditions, using a Time Projection Chamber (TPC) filled with 40 tons of Liquid Argon and equipped with more than 200000 Silicon Photomultipliers (SiPMs) operated at cryogenic temperature. Since many years, the Bruno Kessler Foundation has been involved in the development of different kind of SiPMs sensitive to different wavelengths with low dark count rate and correlated noise. After a long and successful R&D, excellent results have been obtained, fully matching the specifications required by a background-free liquid argon experiment. The TPC will be instrumented with 8280 Photo Detection Modules each made by a SiPM tile of 25 cm2 and a Front End Board, in an acrylic mechanical structure. A dedicated cryogenic electronics with an optical transmission of the signal has been developed to read out the large SiPM area and reduce the mass of the cables in the cryostat due to the wide number of independent channels guaranteeing at the same time a high level of radiopurity. Moreover, the assembly of such a huge number of photodetectors demands a dedicated facility: the DarkSide strategy and working plan will be also reported.