Acoustic wave device

An acoustic wave device comprising:

• a package substrate including a first main surface;
• and
• an acoustic wave element chip that is mounted on the first main surface of the package substrate and includes:
• a piezoelectric layer including a second main surface and a third main surface that face each other;
• and
• a plurality of interdigital transducer (IDT) IDT electrodes that are provided at the second main surface located on a first main surface side among the second main surface and the third main surface, each IDT electrode including a plurality of electrode fingers;
• wherein
• a series arm resonator and a plurality of parallel arm resonators, each including the IDT electrode, are provided on the second main surface of the piezoelectric layer;
• the first main surface of the package substrate includes a first side and a second side that face each other, the second main surface of the piezoelectric layer includes a first edge portion located closer to the first side among the first side and the second side and a second edge portion facing the first edge portion in a plan view, and a distance between the first side and the first edge portion is longer than a distance between the second side and the second edge portion in the plan view;
• the piezoelectric layer has a Z-axis as a crystal axis, and the Z-axis is inclined with respect to a thickness direction of the piezoelectric layer so as to be directed toward a first edge portion side as the Z-axis is directed from the third main surface toward the second main surface of the piezoelectric layer;
• and
• when an IDT electrode at a position closest to the first edge portion among the plurality of IDT electrodes is set as an edge-side IDT electrode, the IDT electrode of a parallel arm resonator at a position closest to an input end side among the plurality of parallel arm resonators is the edge-side IDT electrode.

An acoustic wave device comprising:

• a package substrate including a first main surface;
• and
• an acoustic wave element chip that is mounted on the first main surface of the package substrate and includes:
• a piezoelectric layer including a second main surface and a third main surface that face each other;
• and
• a plurality of interdigital transducer (IDT) electrodes that are provided at the second main surface located on a first main surface side among the second main surface and the third main surface, each IDT electrode including a plurality of electrode fingers;
• wherein
• a plurality of surface acoustic wave resonators, each including the IDT electrode, are provided on the second main surface of the piezoelectric layer, and the plurality of surface acoustic wave resonators include a series arm resonator and a plurality of parallel arm resonators;
• the first main surface of the package substrate includes a first side and a second side that face each other, the second main surface of the piezoelectric layer includes a first edge portion located closer to the first side among the first side and the second side and a second edge portion facing the first edge portion in a plan view, and a distance between the first side and the first edge portion is longer than a distance between the second side and the second edge portion in the plan view;
• the piezoelectric layer has a Z-axis as a crystal axis, and the Z-axis is inclined with respect to a thickness direction of the piezoelectric layer so as to be directed toward a first edge portion side as the Z-axis is directed from the third main surface toward the second main surface of the piezoelectric layer;
• when the IDT electrode is viewed from a direction perpendicular to a direction in which the plurality of electrode fingers extend, a region in which the electrode fingers adjacent to each other overlap each other is an intersection region, and a dimension of the intersection region along the direction in which the plurality of electrode fingers extend is an intersection width;
• and
• when an IDT electrode at a position closest to the first edge portion among the plurality of IDT electrodes is set as an edge-side IDT electrode, the IDT electrode of the parallel arm resonator that is not split in series is the edge-side IDT electrode, and a product of the intersection width and a number of pairs of the plurality of electrode fingers of the edge-side IDT electrode is smaller than a product of the intersection width and the number of pairs of the plurality of electrode fingers of the IDT electrode in at least one surface acoustic wave resonator among the surface acoustic wave resonators at a position closest to an input end side.