A filter includes a support substrate, a piezoelectric layer, one or more series resonators connected in series between input and output terminals, each having first electrode fingers having a first average pitch, one or more parallel resonators having one end connected to a path and another end connected to a ground, each having second electrode fingers having a second average pitch more than a maximum first average pitch, another resonator having one end connected to the path, and having third electrode fingers having a third average pitch less than or equal to an intermediate value between the maximum first average pitch and a minimum second average pitch, and an inductor having one end connected to the another resonator and another end connected to the ground, and having an inductance more than a maximum inductance of another inductor connected between the parallel resonators and the ground.

Aspects of this disclosure relate to a multiplexer with an acoustic assisted trap circuit. The multiplexer includes an acoustic wave filter with an acoustic wave resonator and an impedance network that together provide a trap for a harmonic associated with another acoustic wave filter of the multiplexer. The acoustic wave filter can have an edge of a passband that is farther from the harmonic than other acoustic filters of the multiplexer.

An electronic component comprises a substrate including a main surface on which a functional unit is formed and a cap layer defining a cavity enclosing and covering the functional unit. The cap layer is provided with holes communicating an inside of the cavity with an outside of the cavity. A resin layer covers the cap layer and the main surface and includes one or more bores and a solder layer having a thickness less than a thickness of the resin layer disposed within the one or more bores.

An electronic component comprises a substrate including a main surface on which a functional unit is formed and a cap layer defining a cavity enclosing and covering the functional unit. The cap layer is provided with holes communicating an inside of the cavity with an outside of the cavity. A resin layer covers the cap layer and the main surface and includes one or more bores and a solder layer having a thickness less than a thickness of the resin layer disposed within the one or more bores.

A multiplexer includes a first transmission filter connected to a common terminal, a reception filter, a second transmission filter, and a multilayer substrate. The first transmission filter includes a first parallel-arm resonator connected to a first parallel-arm terminal and a second parallel-arm resonator connected to a second parallel-arm terminal. The second transmission filter includes a third parallel-arm resonator connected to a third parallel-arm terminal and a fourth parallel-arm resonator connected to a fourth parallel-arm terminal. The first to fourth parallel-arm resonators are surface-mounted on a main surface of the multilayer substrate. The second and third parallel-arm terminals are grounded on any dielectric layer from the main surface to an n-th dielectric layer of the multilayer substrate and the first and fourth parallel-arm terminals are isolated from each other on the dielectric layers from the main surface to the n-th dielectric layer.

A surface acoustic wave resonator includes one IDT electrode and reflectors. When a distance between an electrode finger Fe(k) and an electrode finger Fe(k+1) is defined as a k-th electrode finger pitch, in an electrode finger Fe(k−1), the electrode finger Fe(k), and the electrode finger Fe(k+1), a value obtained by dividing a difference between the electrode finger pitch and a section average electrode finger pitch, which is an average of the electrode finger pitch and the electrode finger pitch, by an overall average electrode finger pitch is defined as a pitch deviation ratio, and a distribution obtained by calculating the pitch deviation ratio for all electrode fingers of the IDT electrode or the reflectors is defined as a histogram of the pitch deviation ratio, the IDT electrode or the reflectors have a standard deviation of the pitch deviation ratio in the histogram larger than or equal to about 0.2%.

An acoustic wave device includes a first substrate, an acoustic wave element provided on a first surface of the piezoelectric layer, a second substrate, a first metal layer provided on the first surface and conductively connected to the acoustic wave element, a second metal layer provided on a second surface of the second substrate, a third metal layer that connects the first metal layer to the second metal layer, is thicker than the first metal layer and the second metal layer, and contains copper or silver, and a first conductive layer that covers a side surface of the third metal layer, and a third surface of the first metal layer in a region surrounding another region where the third metal layer is bonded to the first metal layer, is thinner than the third metal layer, and contains a component other than copper, silver, and tin as a main component.

The multiplexer includes a plurality of IDT electrodes on a substrate, an insulating cover located on the substrate so as to configure one or more spaces above the plurality of IDT electrodes, an antenna terminal, transmission terminal, and reception terminal which are all located on the substrate and pass through the cover, and a reinforcing layer which is located on the cover and is made of metal. By the plurality of IDT electrodes, a transmission filter located in a signal path connecting the antenna terminal and the transmission terminal and a receiving filter located in a signal path connecting the antenna terminal and the reception terminal. The reinforcing layer includes a first area part facing the transmission filter and a second area part which faces the receiving filter and is separated from the first area part.

An acoustic wave device includes a substrate, a multilayer film on the substrate, an LT layer configured by a single crystal of LiTaO.sub.3 on the multilayer film, and an IDT electrode on the LT layer. The thickness of the LT layer is 0.3λ or less where λ is two times a pitch p of electrode fingers in the IDT electrode. Euler angles of the LT layer are (0°±20°, −5° to 65°, 0°±10°), (−120°±20°, −5° to 65°, 0°±10°), or (120°±20°, −5° to 65°, 0°±10°). The multilayer film configured by alternately stacking at least one first layer and at least one second layer. The first layer is comprised of SiO.sub.2. The second layer is comprised of any one of Ta.sub.2O.sub.5, HfO.sub.2, ZrO.sub.2, TiO.sub.2, and MgO.

An acoustic wave device includes a substrate, a multilayer film on the substrate, an LT layer configured by a single crystal of LiTaO.sub.3 on the multilayer film, and an IDT electrode on the LT layer. The thickness of the LT layer is 0.3λ or less where λ is two times a pitch p of electrode fingers in the IDT electrode. Euler angles of the LT layer are (0°±20°, −5° to 65°, 0°±10°), (−120°±20°, −5° to 65°, 0°±10°), or (120°±20°, −5° to 65°, 0°±10°). The multilayer film configured by alternately stacking at least one first layer and at least one second layer. The first layer is comprised of SiO.sub.2. The second layer is comprised of any one of Ta.sub.2O.sub.5, HfO.sub.2, ZrO.sub.2, TiO.sub.2, and MgO.