METHOD OF MANUFACTURING FILTER DEVICE

PROBLEM TO BE SOLVED: To provide a filter device having small dispersion of a passing loss of signals. SOLUTION: The filter device includes a plating layer formed on the entire surface of pipes 31 and made of copper or silver in resonant elements 23, and junction sections of which the plating layers of lower end faces 31b of at least the pipes 31 are joined to an inner surface of a casing 22 by solders 28. In a method of manufacturing the casing 22, the resonant elements 23 are attached to a frame body 24 or a lid 25, the creamy solders 28 are applied to the positions of the junction sections, and then heating is performed to obtain the casing. In this case, the solders 28 are applied near positions, where the inner peripheral surfaces of the resonant elements 23 cross the inner surfaces of the casing at the junction sections, thus preventing the solders 28 from easily outflowing to outer peripheries of the resonant elements 23, preventing reservoirs of the solders 28 from occurring easily, and hence stabilizing a shape and reducing a dispersion of a Q value. COPYRIGHT: (C)2011,JPO&INPIT