A SAW filter includes a substrate including a piezoelectric substrate, a transmission filter, and an additional resonator. The transmission filter is a ladder-type filter filtering signals from a transmission terminal and outputting the result to an antenna terminal. Further, the transmission filter includes one or more serial resonators and one or more parallel resonators which are connected in a ladder configuration on the piezoelectric substrate. An initial stage resonator is the serial resonator. The additional resonator includes an IDT electrode on the piezoelectric substrate. The IDT electrode is connected to the transmission terminal at a stage before the transmission filter and is connected to any of the one or more GND terminals. In the additional resonator, a resonance frequency and an antiresonance frequency are located outside of a passband of the transmission filter.

An electronic device includes an insulation material layer provided on a first main surface of a piezoelectric substrate and surrounding a functional element, and a protective layer provided on the insulation material layer. The piezoelectric substrate and the insulation material layer define a hollow portion accommodating the functional element. The protective layer includes a first portion above the hollow portion, a second portion adjacent to the first portion at one end of the second portion, and a third portion adjacent to the second portion at another end of the second portion. A distance between the first main surface and a surface of the protective layer in the thickness direction is greatest at a location where the second portion is adjacent to or in a vicinity of the first portion, and the distance is shortest at a location where the second portion is adjacent to or in a vicinity of the third portion.

An acoustic wave device includes a piezoelectric substrate, functional elements, an outer peripheral support layer, a cover portion, and a protective layer covering the cover portion. A hollow space is defined by the piezoelectric substrate, the outer peripheral support layer, and the cover portion, and the functional elements are disposed in the hollow space. The acoustic wave device further includes an under bump metal layer, a wiring pattern, and a through-electrode that connects these elements. In the protective layer, a through-hole to be filled with a conductor to electrically connect a solder ball and the under bump metal layer is provided. The outer peripheral support layer includes a protruding portion protruding to the hollow space. When the acoustic wave device is seen in plan view, at least a portion of the through-hole overlaps the hollow space, and an end portion of the protruding portion overlaps an inner region of the through-hole.

An acoustic wave device includes a piezoelectric substrate that includes first and second main surfaces, an IDT electrode on the first main surface, a support having a rectangular or substantially rectangular frame shape and including a cavity, first and second sides, and a first corner portion connected to the first and second sides, and the support being provided on the first main surface such that the cavity surrounds the IDT electrode, and a cover on the support and covering the cavity. A straight or substantially straight grinding trace is provided on the second main surface. The grinding trace leads to the first corner portion as viewed in plan. One of an angle between the first side and the grinding trace and an angle between the second side and the grinding trace as viewed in plan is about 9.5° or less.

The invention relates to a covering (1) for an electronic component (e.g. of the MEMS, BAW, or SAW type). The covering comprises at least one layer (5, 6, 7) having a structure (19, 20, 21) with a number of prominences (8, 9, 15) and/or depressions (10, 11, 16). The invention furthermore relates to a method for producing a covering (1) of this type.

Multiplexers are disclosed. A multiplexer can include a first filter and a second filter that are coupled to a common node. The second filter can include a first type of acoustic wave resonators (e.g., bulk acoustic wave resonators) and a series acoustic wave resonator of a second type (e.g., a surface acoustic wave resonator) that is coupled between the acoustic wave resonators of the first type and the common node. The first filter can provide a single-ended radio frequency signal. In certain embodiments, the first filter can be a receive filter and the second filter can be a transmit filter.

Methods of making packaged surface acoustic wave devices are provided. The method may include forming a photosensitive resin coat over a cavity-defining structure encapsulating a surface acoustic wave device. The photosensitive resin coat may be formed using a spin-coating process, and then patterned to form a desired shape. Portions of the photosensitive resin may be removed from areas near the edge of the die, to facilitate separation of a wafer into individual dies. The method may also include forming a conductive structure using a plating process, where the conductive structure is located between the resin coat and the cavity defining structure. The photosensitive resin can include a phenol resin. The packaged surface acoustic wave devices made using a photosensitive resin coat may be relatively thin, and may have a height of less than 220 micrometers.

Disclosed is a surface acoustic wave (SAW) wafer level package including a substrate, an interdigital transducer (IDT) formed on the substrate, a sidewall formed on the substrate along a periphery of the IDT, a cover formed above the sidewall and the IDT to form a hollow above the IDT with the sidewall, a connection electrode formed on the substrate, electrically connected to the IDT, and extending outward from a periphery of the sidewall, a connection terminal electrically connected to a part of the connection electrode which extends outward from the periphery of the sidewall, formed throughout one outer surface of the sidewall and one surface and a part of a top surface of the cover, and having a top surface formed to be higher than the top surface of the cover, and an organic solderability preservative (OSP) coating layer formed on at least the top surface of the connection terminal.

An acoustic wave device includes a support substrate having a central region and a surrounding region located around the central region, a silicon oxide film that is located in the central region directly or indirectly and that has a side surface, a piezoelectric layer that is provided on the silicon oxide film and that has a first principal surface and a second principal surface, an excitation electrode provided on at least one of the first principal surface and the second principal surface, a cover film provided to cover the entire side surface of the silicon oxide film, a resin layer that is provided in the surrounding region and that is provided to cover the side surface of the silicon oxide film from above the cover film, and a wiring electrode that is electrically connected to the excitation electrode and that extends from the piezoelectric layer to the resin layer.

An acoustic resonator assembly and a filter are disclosed. The acoustic resonator assembly includes at least two acoustic resonators vertically connected to each other. The acoustic resonator includes: an acoustic mirror, a bottom electrode layer, a piezoelectric layer, and a top electrode layer that are arranged on a substrate. An active area of the acoustic resonator is defined by an overlapping area of the acoustic mirror, the bottom electrode layer, the piezoelectric layer, and the top electrode layer. The acoustic resonator further includes a support layer arranged on the substrate or the piezoelectric layer on a periphery of a projection of the acoustic mirror on the substrate. The at least two acoustic resonators are vertically connected to each other through the support layer. The filter significantly reduces the volume and the area of a device, improves design freedom and reduces design difficulty, enhances product performance and greatly reduces costs.