Abstract: In a method for producing a boundary acoustic wave device that includes a first medium, a second medium, and a third medium laminated in that order, and electrodes disposed at the interface between the first medium and the second medium, the method includes the steps of preparing a laminate including the first medium, the second medium, and the electrodes disposed at the interface between the first medium and the second medium, adjusting the thickness of the second medium after the step of preparing the laminate to regulate a frequency or the acoustic velocity of a surface acoustic wave, a pseudo-boundary acoustic wave, or a boundary acoustic wave, after the adjusting step, forming the third medium different from the second medium in terms of the acoustic velocity with which the boundary acoustic wave propagates therethrough and/or in terms of material.

Abstract: A boundary acoustic wave device includes a stacked structure including a second medium, an IDT electrode, and a first medium, the stacked structure including the first medium having a temperature coefficient of group delay time TCD that is positive. The IDT electrode is stacked on the first medium. The second medium is stacked on the first medium so as to cover the IDT electrode and has a temperature coefficient of group delay time TCD that is negative. A third medium having an acoustic velocity of a transverse wave that is less than an acoustic velocity of a transverse wave of the second medium is arranged at least on a top surface of the IDT electrode.

Abstract: A boundary acoustic wave device efficiently traps the vibrational energy of boundary acoustic waves and exhibits a high electromechanical coupling coefficient, and is consequently not affected by higher-order modes. The boundary acoustic wave device includes a first medium having piezoelectric characteristics, a non-electroconductive second medium, and a third medium through which slow transverse waves propagate at a lower acoustic velocity than slow transverse waves propagating through the first and second media. The first medium, the third medium, and the second medium are stacked in that order. An IDT is disposed between the first medium and the third medium. The IDT includes a metal layer made of a metal having a density ? in the range of about 3000 kg/m3 to about 21500 kg/m3. The IDT has electrode fingers arranged at a pitch of ? and has a thickness H1 satisfying the relationship 0.006??H1?0.2?, and the third medium has a thickness H2 satisfying the relationship H1<H2?0.7?.

Abstract: A boundary acoustic wave device using SH boundary acoustic waves includes a first medium layer, a second medium layer stacked on the first medium layer, and an electrode including an interdigital electrode and reflectors. A sound absorbing layer is provided on the surface of the first medium layer and/or the second medium layer opposite the interface therebetween.

Abstract: A boundary acoustic wave device has a small thickness, which is suitable for thin apparatuses, and can be manufactured at low cost. The boundary acoustic wave device includes a first IDT electrode disposed on a first surface of a substrate, a first insulating film covering the first IDT electrode, a second IDT electrode disposed on a second surface of the substrate, and a second insulating film covering the second IDT electrode. Either the substrate or the first and second insulating films have piezoelectric characteristics.

Abstract: A boundary acoustic wave device includes a first medium, a second medium, a third medium, and a fourth medium that are laminated in that order and, an electrode including an IDT electrode disposed at an interface between the first medium and the second medium, the temperature coefficient of delay time TCD of a boundary acoustic wave has a positive value, the fourth medium or the second medium has a positive temperature coefficient of sound velocity TCV, the first medium has a negative temperature coefficient of sound velocity TCV, and the sound velocity of transverse wave of the third medium is set to be less than the sound velocity of transverse wave of the fourth medium and/or the second medium.

Abstract: An elastic wave device includes at least one IDT electrode provided on a piezoelectric substrate. The at least one IDT electrode includes first and second electrode fingers arranged next to each other in a propagation direction of elastic wave. The side edges of at least the electrode finger of the first and second electrode fingers are provided with projections. The position of the projections in the longitudinal direction of the electrode fingers substantially corresponds with the position of a gap in the longitudinal direction of the electrode fingers, the gap being provided at the tip end of the electrode finger of the first and second electrode fingers.

Abstract: A boundary acoustic wave device includes a quartz substrate, an IDT located on the substrate, and a dielectric arranged so as to cover the IDT. A boundary acoustic wave propagates across a boundary between the quartz substrate and the dielectric. The thickness of the IDT is determined so that the velocity of the SH boundary acoustic wave is below those of a slow transverse wave propagating across the quartz substrate and a slow transverse wave propagating across the dielectric. The Eulerian angles of the quartz substrate lie within hatched regions in FIG. 13.

Abstract: A dielectric substance is laminated on one surface of a piezoelectric substance, and an IDT and reflectors are disposed as electrodes at a boundary between the piezoelectric substance and the dielectric substance, and the thickness of the electrodes is determined so that the acoustic velocity of the Stoneley wave is decreased less than that of a slow transverse wave propagating through the dielectric substance and that of a slow transverse wave propagating through the piezoelectric substance, thereby forming a boundary acoustic wave device.

Abstract: A boundary acoustic wave device using SH boundary acoustic waves includes a first medium layer, a second medium layer stacked on the first medium layer, and an electrode including an interdigital electrode and reflectors. A sound absorbing layer is provided on the surface of the first medium layer and/or the second medium layer opposite the interface therebetween.

Abstract: A boundary acoustic wave device includes a dielectric substance that is laminated on one surface of a piezoelectric substance, an IDT and reflectors used as electrodes are disposed at a boundary between the piezoelectric substance and the dielectric substance, and the thicknesses of the electrodes are set such that the acoustic velocity of the SH type boundary acoustic wave is less than that of a slow transverse wave propagating in the dielectric substance and than that of a slow transverse wave propagating in the piezoelectric substance, so that a boundary acoustic wave device is formed.

Abstract: A boundary acoustic wave device includes a first medium, a second medium, and an IDT electrode disposed at an interface between the first medium and the second medium, the IDT electrode having an Au layer defining a main electrode layer, wherein a Ni layer is laminated so as to contact at least one surface of the Au layer, and a portion of Ni defining the Ni layer is diffused from the Ni layer side surface of the Au layer toward the inside of the Au layer.

Abstract: A boundary acoustic wave device is provided in which an increase in the conductor resistance can be suppressed and a satisfactorily high electromechanical coupling coefficient K2 can be achieved even when the frequency is increased. The boundary acoustic wave device includes a first medium, a second medium, and an IDT provided therebetween. In the boundary acoustic wave device, a plane that separates the IDT into two equal parts in the thickness direction is defined as a boundary plane, the energy of boundary acoustic waves that is present at the first medium side of the boundary plane is represented by E1, and the energy that is present at the second medium side of the boundary plane is represented by E2.

Abstract: A boundary acoustic wave device includes a LiNbO3 substrate defining a first medium layer having a relatively high sound velocity and a SiO2 film defining a second medium layer having a relatively low sound velocity, an electroacoustic transducer and reflectors disposed between the first medium layer and the second medium layer, and recess portions and/or protrusion portions provided in the upper surface of the SiO2 film.

Abstract: An elastic wave filter of a resonator type includes at least one IDT electrode arranged so as to contact the piezoelectric substance. The elastic wave filter is arranged such that an elastic wave in a main propagation mode for obtaining target frequency characteristics and an elastic wave in a sub-propagation mode propagate, the elastic wave being capable of propagating simultaneously with the elastic wave in the main propagation mode, an electromechanical coefficient K2 of the elastic wave in the sub-propagation mode is in the range from about 0.1% to about one third of an electromechanical coefficient K2 of the elastic wave in the main propagation mode, and a sound velocity of the elastic wave in the sub-propagation mode differs from a sound velocity of the elastic wave in the main propagation mode.

Abstract: A dielectric substance is laminated on one surface of a piezoelectric substance, and an IDT and reflectors are disposed as electrodes at a boundary between the piezoelectric substance and the dielectric substance, and the thickness of the electrodes is determined so that the acoustic velocity of the Stoneley wave is decreased less than that of a slow transverse wave propagating through the dielectric substance and that of a slow transverse wave propagating through the piezoelectric substance, thereby forming a boundary acoustic wave device.

Abstract: An elastic boundary wave device includes an IDT including laminated conductor layers disposed between a first medium and a second medium, wherein a plane that divides the IDT in half in the thickness direction defines an interface, the energy of an elastic boundary wave present on the side of the first medium of the interface is denoted as E1, and the energy of an elastic boundary wave present on the side of the second medium of the interface is denoted as E2, and wherein if the IDT included only a conductor having the highest density among the laminated conductor layers of the IDT, when the energy of an elastic boundary wave present on the side of the first medium of the interface is denoted as E1? and the energy of an elastic boundary wave present on the side of the second medium of the interface is denoted as E2?, the energies of an elastic boundary wave would satisfy the relationship of E1/E2<E1?/E2? so that the sonic velocity of an elastic boundary wave in the IDT including the laminated conductor lay

Abstract: An elastic boundary wave apparatus that is capable of suppressing an undesired response due to a comb-shaped capacitor electrode includes a first medium; a second medium stacked on the first medium; and a plurality of electrodes arranged in the boundary between the first and second media, wherein a filter and/or a resonator, and an electrostatic capacitor that is electrically connected to the filter and/or the resonator are defined by the plurality of electrodes, the filter and/or the resonator each include an IDT electrode, and the electrostatic capacitor is defined by a comb-shaped capacitor electrode.

Abstract: A boundary acoustic wave filter device capable of increasing an out-of-band attenuation includes a dielectric film formed on a piezoelectric substrate, at least one longitudinally coupled resonator boundary acoustic wave filter having a plurality of IDTs disposed along a boundary between the piezoelectric substrate and the dielectric film, and at least two one-terminal-pair boundary acoustic wave resonators. At least one boundary acoustic wave resonator is connected in series to the longitudinally coupled resonator boundary acoustic wave filter, and at least remaining one boundary acoustic wave resonator is connected in parallel to the longitudinally coupled resonator boundary acoustic wave filter.

Abstract: A boundary acoustic wave device includes a quartz substrate, an IDT located on the substrate, and a dielectric arranged so as to cover the IDT. A boundary acoustic wave propagates across a boundary between the quartz substrate and the dielectric. The thickness of the IDT is determined so that the velocity of the SH boundary acoustic wave is below those of a slow transverse wave propagating across the quartz substrate and a slow transverse wave propagating across the dielectric. The Eulerian angles of the quartz substrate lie within hatched regions in FIG. 13.