An elastic wave device includes a support substrate made of silicon, a piezoelectric film disposed directly or indirectly on the support substrate, and an interdigital transducer electrode disposed on one surface of the piezoelectric film. A higher-order mode acoustic velocity of propagation through the piezoelectric film is equal or substantially equal to an acoustic velocity V.sub.si=(V.sub.1).sup.1/2 of propagation through silicon or higher than the acoustic velocity V.sub.si, where V.sub.si is specified by V.sub.1 among solutions V.sub.1, V.sub.2, and V.sub.3 with respect to x derived from Ax.sup.3+Bx.sup.2+Cx+D=0.

A packaging method and package structure for a filter chip. The packaging method includes providing a circuit substrate, covering a first surface of the circuit substrate and/or filter chip with adhesive material and forming recessed cavities or closed cavities in the adhesive material. The method further includes adhering the filter chip to the first surface of circuit substrate via the adhesive material, such that surface acoustic wave transmitting regions of the filter chip correspond to the recessed cavities or closed cavities in the adhesive material to form a gap therebetween, and encapsulating the filter chip with encapsulating material. The method further includes forming interconnecting holes extending from a second surface of the circuit substrate to pins of the filter chip, filling the interconnecting holes with conductive material, so that the conductive material is in electrical contact with a chip pin bump or pad metal of the filter chip, and forming external pin pads on the second surface.

In a SAW element, a piezoelectric layer is laid over a support substrate. An IDT electrode includes a main region and two end regions on two sides of the main region. The end region continues from a portion where electrode finger design is modified up to the end part. A resonance frequency determined by electrode finger design of reflector electrode fingers is lower than a resonance frequency determined by electrode finger design of electrode fingers in the main region. An interval between centers of the electrode fingers in the main region is defined as “a”. Number of electrode fingers configuring the end region is defined as “m”. A distance between a center of an electrode finger among the electrode fingers in the main region which is located on a side closest to the end region and a center of a reflector electrode finger among the reflector electrode fingers which is located on a side closest to the end region is defined as “x”. At this time, the following relationship is satisfied:

0.5×a×(m+1)<x<a×(m+1)

A composite substrate includes a supporting substrate and a functional substrate that are directly joined together, the supporting substrate being a sintered sialon body.

An acoustic wave device includes a support substrate and first and second resonant sections adjacent to each other on the support substrate. Each of the first and second resonant sections includes a piezoelectric thin film, an IDT electrode on the piezoelectric thin film, and a support layer surrounding the piezoelectric thin film in a plan view of the acoustic wave device. The support layer has a different linear expansion coefficient from the piezoelectric thin film. The piezoelectric thin film in the first resonant section and the piezoelectric thin film in the second resonant section are divided by the support layer between the resonant section and the resonant section.

A composite multiplexer includes a first multiplexer, a second multiplexer, and a second LC circuit. The first multiplexer includes first band pass filter circuits and first LC circuits connected to end portions of the first band pass filter circuits that are opposite to a first terminal, respectively. The second multiplexer includes second band pass filter circuits. The second LC circuit is connected between the first terminal and the second multiplexer.

A circuit module includes a mounting substrate including a conductor wiring, an elastic wave element provided in or on a main surface of the mounting substrate, an electric element provided in or on the main surface, the electric element being different from the elastic wave element, and an insulating resin portion provided in or on the main surface to cover the elastic wave element and the electric element. The elastic wave element and the electric element are connected to each other by the conductor wiring. A height of the elastic wave element is about 0.28 mm or less, which is less than that of the electric element. The thickness of the resin portion in a region in which the resin portion covers the elastic wave element is greater than the thickness of the resin portion in a region in which the resin portion covers the electric element.

A surface acoustic wave device includes a piezoelectric substrate, an IDT electrode, a support layer, a cover layer, and a pillar-shaped electrode. The IDT electrode is provided on a main surface of the piezoelectric substrate. The support layer is disposed around a region where the IDT electrode is provided and has a larger height from the main surfaces than a height of the IDT electrode therefrom. The cover layer is disposed on the support layer and covers the IDT electrode. The pillar-shaped electrode is located on one of the main surfaces where the pillar-shaped electrode is in contact with the support layer. The pillar-shaped electrode is electrically connected to the IDT electrode. The pillar-shaped electrode includes a top surface and a side surface. Each of the top surface and the side surface includes a portion exposed to outside.

A wiring substrate includes a substrate with a first principal face and a second principal face. The first principal face has a first corner and first and second sides. The second principal face has a second corner corresponding to the first corner, and a third and a fourth side, respectively corresponding to the first and second sides. The substrate further comprising a first side surface connected to the first side, a second side surface connected to the second side, a third side surface connected to the third side, a fourth side surface connected to the fourth side, a first fracture part located between the first and third side surfaces to connect them, and a second fracture part located between the second and the fourth side surfaces to connect them. In the substrate's thickness direction, the length of the second side surface is smaller than the first side surface.

A multiplexer includes: first and second substrates overlapping with each other with an air gap interposed therebetween; a first filter disposed on the first substrate and including first series resonators connected in series with a first path, and first parallel resonators; and a second filter disposed on the second substrate and including second series resonators connected in series with a second path, and second parallel resonators connected between the second path and a ground, each of the second series resonators and the second parallel resonators including a piezoelectric film, a first electrode interposed between the piezoelectric film and the second substrate, a second electrode interposed between the piezoelectric film and the air gap, and a resonance region, in at least one second parallel resonator, the first electrode being coupled to the second path, the second electrode being coupled to the ground, the resonance region overlapping with the first path.