In a method of manufacturing an electronic device, a substrate having a plurality of mounting regions on which first electronic components and second electronic components are mounted is provided, the substrate having a first surface and a second surface opposite the first surface. First electronic components are mounted on the first surface of the board via first bumps. At least one vapor shielding cover is positioned on the first surface of the substrate to cover at least one of the first electronic components. Second electronic components are mounted on the second surface of the substrate via second bumps. The second bumps are soldered with a vapor phase reflow process and during the vapor phase reflow process, the at least one vapor shielding cover is configured to prevent a heat transfer fluid in a vapor state from moving to the at least one first electronic component covered by the at least one vapor shielding cover.