PURPOSE: To increase the efficiency of an assembly by forming a groove, which bends a metallic thin film according to the rotation so as to press a base body, in each of the outer peripheral surface of a pair of cylindrical rollers rotated reversely to each other so as to eliminate the wrinkles of the thin film in order to improve the heat conductive efficiency and perform the assembly continuously.

CONSTITUTION: A metallic thin film 13' is inserted into grooves 7A and 7B when grooves 7A and 7B of two rollers 6A and 6B rotated in the directions reverse to each other are located at specified positions, and a porous metallic base body 1 is inserted onto the thin film 13'. While the rollers 6A and 6B are further rotated, the thin film 13' is pressed against the wall surfaces of notch parts 8A and 8B, and bent, whereby the thin film is covered around the metallic base body 1. While the rollers 6A and 6B are further rotated, the end part of the thin film 13' is pressed against the upper surfaces 7A' and 7B' of the grooves 7A and 7B, and bent, whereby the thin film is covered on the upper surface end part of the metallic base body 1. This concludes the installation of an electronic discharge part. When the rollers 6A and 6B are further rotated, the metallic base body 1 covered with the thin film 13' is transported to the lower side of the rollers 6A and 6B.