A bulk wave preventing device of SAW filter

摘要

PURPOSE: An apparatus for preventing an internal wave of a surface acoustic wave filter is provided to improve a characteristic of the surface acoustic wave filter by forming an internal wave shielding portion on a surface of a substrate. CONSTITUTION: A circuit of a surface acoustic wave filter, a multitude of terminal including input and output terminals(13a,13b,13c,13d), and an internal wave shielding portion(S) are formed on an upper portion(12) of a substrate(11) having constant thickness. The internal wave shielding portion(S) is formed on the upper portion(12) of the substrate(11) by an etch process or a scratching process. A silver epoxy, a silicon rubber, a polyimide, a photoresist, and a UV epoxy are used as an internal wave shielding material. An input signal is transferred to the input terminal(13a) through a wire(14a) and a surface wave is transferred to the output terminal(13d) and a wire(14b). The input terminal(13b) and the output terminal(13c) are connected to each other by wire bonding(14c).