Patent ID: 8536958

Claim:
An elastic wave duplexer comprising: a substrate; a transmission elastic wave filter element that is flip-chip mounted to a principal surface of the substrate; a reception elastic wave filter element that is flip-chip mounted to the principal surface of the substrate; and a sealing member arranged on the principal surface of the substrate to cover the transmission elastic wave filter element and the reception elastic wave filter element, which are flip-chip mounted to the principal surface of the substrate, and to seal off the transmission elastic wave filter element and the reception elastic wave filter element, the sealing member including: a base portion in contact with the principal surface of the substrate and made of a first dielectric material; and a lower dielectric-constant portion made of a second dielectric material having a dielectric constant lower than that of the first dielectric material and located in at least one of a region of the sealing member that faces the transmission elastic wave filter element on a side opposite from the substrate with respect to the transmission elastic wave filter element and a region of the sealing member that faces the reception elastic wave filter element on a side opposite from the substrate with respect to the reception elastic wave filter element.