An electronic device includes a support layer is provided on a piezoelectric substrate and surrounds a functional element. A cover layer is located above the support layer, and faces the piezoelectric substrate. A protective layer seals the support layer and the cover layer. The support layer is provided on at least the outer periphery of the piezoelectric substrate, and defines a hollow portion within the outer periphery of the piezoelectric substrate. The protective layer includes a first portion above the hollow portion, a second portion above the support layer, and a curved surface that is convex in an opposite direction from the piezoelectric substrate.

An electro-acoustic resonator comprises a piezoelectric substrate on which an electrode structure is disposed. The electrode structure comprises a metal layer of aluminum and copper, a barrier layer forming a barrier against the diffusion of copper and another metal layer disposed on the barrier layer comprising aluminum. An AlCu intermetallic phase formed after an anneal is restricted to the portion beneath the barrier layer so that Galvano-corrosion of the electrode structure is avoided.

A surface acoustic wave device comprises a substrate and an interdigital transducer (IDT) electrode disposed on the substrate. The IDT electrode includes a lower electrode layer having a lower surface in contact with an upper surface of the substrate and an upper electrode layer having a lower surface defining a base in contact with an upper surface of the lower electrode layer. Side surfaces of the lower electrode layer are substantially perpendicular to the upper surface of the substrate. Side surfaces of the upper electrode layer are disposed at an acute angle relative to the upper surface of the substrate.

An acoustic wave filter includes first and second series-arm resonators, each including an IDT electrode including electrode fingers and a busbar electrode connecting first ends of the electrode fingers to each other. A direction in which second ends of the electrode fingers are aligned with each other crosses a propagation direction of an acoustic wave. The electrode fingers of the IDT electrodes of the first and second series-arm resonators each include an electrode-finger central portion and a wide portion located at the second end and being wider than the electrode-finger central portion. The length of the wide portion of each of the electrode fingers in the first series-arm resonator is greater than the length of the wide portion of each of the electrode fingers in the second series-arm resonator.

An elastic wave device includes a substrate, an IDT electrode, a wire, an electrically insulating film, and an identification marking. The substrate has piezoelectricity. The IDT electrode is provided on the substrate and includes a pair of comb-shaped electrodes facing each other. The wire is provided on the substrate and connected to the IDT electrode. The electrically insulating film is provided at least on the IDT electrode and the wire. The identification marking is defined by an uneven portion of a surface of the electrically insulating film. The identification marking does not to overlap the IDT electrode in plan view of the substrate.

A radio-frequency module includes a multi-filter unit and a switch unit. The multi-filter unit includes filters having different passbands of signals and each including input/output terminals. The switch unit includes a receive/transmit terminal and a GND terminal. The switch unit switches the coupling destination of a second terminal in a second filter between the terminals. In the second filter, the second terminal is a common terminal coupled to a terminal, which is to be at the reference potential, of a first filter. When a first terminal of the first filter is to be coupled to the receive/transmit terminal terminal, the switch unit switches the coupling destination of the second terminal to the ground terminal.

A electronic component includes a connection electrode on a wiring layer. An electrically conductive layer is connected to the wiring layer via the connection electrode. A protective film covers a cover portion and the electrically conductive layer. A solder bump is electrically connected to the electrically conductive layer via an opening. An alloy layer is between the solder bump and the electrically conductive layer in a thickness direction to join the solder bump to the electrically conductive layer and differs in composition and/or elements from the solder bump. The connection electrode does not overlap the solder bump. The surface of the electrically conductive layer that is located on a protective film side is in contact with the protective film between the alloy layer and an edge of the electrically conductive layer that is located on a connection electrode side.

An acoustic wave device includes: a piezoelectric substrate; a comb-shaped electrode located on the piezoelectric substrate; a wiring layer located on the piezoelectric substrate and electrically connected with the comb-shaped electrode; a first insulating film located on the piezoelectric substrate, the first insulating film covering the comb-shaped electrode, having an aperture on the wiring layer, and being thicker than the comb-shaped electrode; a second insulating film covering an upper surface of the first insulating film and at least a part of a side surface of the first insulating film in the aperture and having a higher moisture resistance than the first insulating film; and a pad being in contact with the wiring layer exposed by the aperture.

The aim according to the invention is to suppress a disturbing SH mode in a ladder-type filter. This aim is achieved in that the resonance frequency of the series resonator responsible therefor is moved and, at the same time, the pole zero distance of the series resonator is reduced by parallel connection with a capacitor. The antiresonance of the series resonator and therefore also the passband thus remain unchanged.

A filter includes n series resonators, one or more parallel resonators, a first inductor between a first terminal and a first of the n series resonators, and a second inductor between an n-th series resonator and a second terminal. Where a resonant frequency of the first series resonator is referred to as a first resonant frequency, a resonant frequency of each of the series resonators other than the first series resonator and the n-th series resonator is referred to as a second resonant frequency, and a resonant frequency of the n-th series resonator is referred to as a third resonant frequency, the first resonant frequency and the third resonant frequency are each higher than the second resonant frequency.