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WO2019150992A1 - Filtre piézoélectrique - Google Patents

Filtre piézoélectrique Download PDF

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Publication number
WO2019150992A1
WO2019150992A1 PCT/JP2019/001479 JP2019001479W WO2019150992A1 WO 2019150992 A1 WO2019150992 A1 WO 2019150992A1 JP 2019001479 W JP2019001479 W JP 2019001479W WO 2019150992 A1 WO2019150992 A1 WO 2019150992A1
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WIPO (PCT)
Prior art keywords
piezoelectric
electrode
piezoelectric filter
input
output
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2019/001479
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English (en)
Japanese (ja)
Inventor
幸田　直樹
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Daishinku Corp
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Daishinku Corp
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Filing date
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Priority to JP2019569000A priority Critical patent/JP7205497B2/ja
Priority to CN201980007145.5A priority patent/CN111557076B/zh
Publication of WO2019150992A1 publication Critical patent/WO2019150992A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/56—Monolithic crystal filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/58—Multiple crystal filters
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/88—Mounts; Supports; Enclosures; Casings

Definitions

  • the present invention relates to a piezoelectric filter used for communication equipment such as a mobile phone, electronic equipment, and the like.
  • a piezoelectric filter using a piezoelectric substrate such as an AT-cut quartz plate generally has an input electrode and an output electrode formed on one surface of the piezoelectric substrate, and a common electrode (ground) corresponding to the input / output electrode on the other surface. Electrode).
  • Such a configuration is called a two-pole type piezoelectric filter because it has two electrode pairs with a piezoelectric substrate in between.
  • a two-pole type piezoelectric filter is used in order to improve the characteristics of the piezoelectric filter.
  • a shield electrode facing the input electrode and the output electrode is formed on the inner surface of the package to perform electromagnetic shielding to prevent a reduction in guaranteed attenuation (for example, Patent Documents). 1).
  • Patent Document 1 no particular consideration is given to the floor level inclination of the guaranteed attenuation characteristics.
  • the present invention has been made in view of the above points, and an object thereof is to provide a piezoelectric filter having a high guaranteed attenuation characteristic while flattening the floor level of the guaranteed attenuation characteristic.
  • two piezoelectric filter elements in which an input electrode and an output electrode are formed on one main surface of one piezoelectric substrate and a common electrode is formed on the other main surface are included in the package.
  • the opposing gap is 100 ⁇ m or more.
  • the shield electrode faces at least both the input electrode and the output electrode, it is possible to suppress the electromagnetic coupling between the input electrode and the output electrode and increase the guaranteed attenuation amount, Since the opposing gap between the shield electrode and the two electrodes is 100 ⁇ m or more, the opposing gap becomes too narrow, and the floor level of the guaranteed attenuation characteristic can be suppressed and flattened.
  • the input electrode, the output electrode, and the common electrode are formed on each individual piezoelectric substrate and the piezoelectric filter elements are respectively configured, the piezoelectric substrates are acoustically separated from each other. As compared with the configuration in which the input electrode, the output electrode, and the common electrode of the piezoelectric filter element are formed, the spurious can be suppressed and the filter characteristics can be improved.
  • the facing gap is preferably less than 360 ⁇ m.
  • each piezoelectric substrate of each piezoelectric filter element is rectangular in plan view, and each piezoelectric substrate is held by the package at three corners of the rectangle.
  • each piezoelectric substrate that is rectangular in plan view is held in the package at the three corners of the rectangle, so that the piezoelectric substrate can be stably held without tilting.
  • the opposing gap between the shield electrode on the inner surface of the package and both the input electrode and the output electrode of the piezoelectric substrate can be stably maintained.
  • Each input electrode, each output electrode, and each common electrode of each piezoelectric substrate of each piezoelectric filter element are individually connected to each external connection terminal provided independently on the package. Is preferred.
  • each electrode of each piezoelectric substrate is individually connected to an independent external connection terminal of the package, that is, each electrode of each piezoelectric substrate is independently connected to each external connection within the package. Since it is connected to the terminal, each electrode can be prevented from affecting each other, and the guaranteed attenuation can be increased.
  • the package has a rectangular storage recess in which the two piezoelectric filter elements are stored, and a corner of the storage recess facing each other of the external connection terminals of the piezoelectric filter.
  • An input electrode pad and an output electrode pad respectively connected to an external connection terminal for input and an external connection terminal for output of the piezoelectric filter are formed, and the input electrode and the other of the piezoelectric substrate of one piezoelectric filter element are formed.
  • the output electrodes of the piezoelectric substrate of the piezoelectric filter element may be drawn out to the opposing corners and connected to the input electrode pad and the output electrode pad, respectively.
  • the input electrode of the piezoelectric substrate of one of the two piezoelectric filter elements housed in the housing recess of the package and the output electrode of the piezoelectric substrate of the other piezoelectric filter element are rectangular in plan view. Since the input electrode pad and the output electrode pad at the opposite corners of the storage recess are respectively connected to the external connection terminal for input and the external connection terminal for output, the external input terminal for the piezoelectric filter The connection terminal and the like and the external connection terminal for output can be arranged at the farthest opposite corners. As a result, the mutual attenuation can be suppressed and the guaranteed attenuation can be increased.
  • the two piezoelectric filter elements are arranged such that the output electrode of the piezoelectric substrate of the one piezoelectric filter element and the input electrode of the piezoelectric substrate of the other piezoelectric filter element are close to each other. It is preferable to juxtapose the storage recess.
  • the input electrode and the output electrode of each of the two piezoelectric filter elements are formed on the one main surface of each piezoelectric substrate with a space therebetween, and the shield electrode is formed on the one main surface.
  • the inner surface of the package that is formed on the inner surface of the package continuously so as to face both of the electrodes and that faces the spaced-apart region, and the inner surface of the package on which the shield electrode is continuously formed is flat. Preferably there is.
  • the shield electrode facing the region where the space between the input electrode and the output electrode is spaced is formed continuously on the inner surface of the flat package, for example, the region facing the space
  • the configuration is simplified as compared with those that form protrusions and the like.
  • the piezoelectric substrate is preferably a quartz substrate.
  • the frequency-temperature characteristic is good.
  • the shield electrode is opposed to at least both the input electrode and the output electrode, the electromagnetic coupling between the input electrode and the output electrode is suppressed to increase the guaranteed attenuation amount.
  • the facing gap between the shield electrode and the two electrodes is 100 ⁇ m or more, the facing gap becomes too narrow and the floor level of the guaranteed attenuation characteristic is suppressed and flattened. Can do.
  • the input electrode, the output electrode, and the common electrode are formed on each individual piezoelectric substrate and the piezoelectric filter elements are respectively configured, the piezoelectric substrates are acoustically separated from each other. As compared with the configuration in which the input electrode, the output electrode, and the common electrode of the piezoelectric filter element are formed, the spurious can be suppressed and the filter characteristics can be improved.
  • FIG. 1 is a longitudinal sectional view of a piezoelectric filter according to an embodiment of the present invention.
  • FIG. 2 is a plan view showing a state in which the lid of the piezoelectric filter of FIG. 1 is removed.
  • FIG. 3 is a plan view of the base of the piezoelectric filter of FIG.
  • FIG. 4 is a schematic diagram showing the configuration of the piezoelectric filter of FIG.
  • FIG. 5 is a plan view corresponding to FIG. 2 of the piezoelectric filter of the comparative example.
  • FIG. 6 is a diagram showing filter characteristics of the piezoelectric filter of FIG.
  • FIG. 7 is a longitudinal sectional view corresponding to FIG. 1 of a piezoelectric filter of another comparative example.
  • FIG. 8 is a diagram showing the filter characteristics of the piezoelectric filter of FIG.
  • FIG. 9 is a diagram showing the filter characteristics of another comparative example of a piezoelectric filter.
  • FIG. 10 is a diagram illustrating filter characteristics of the piezoelectric filter of the example according to the embodiment of FIG.
  • FIG. 11 is a diagram illustrating filter characteristics of a piezoelectric filter according to another embodiment.
  • FIG. 1 is a longitudinal sectional view of a piezoelectric filter according to an embodiment of the present invention
  • FIG. 2 is a plan view of the piezoelectric filter of FIG. 1 with a lid removed
  • FIG. 3 is a plan view of FIG.
  • FIG. 4 is a plan view of the base of the piezoelectric filter
  • FIG. 4 is a schematic diagram showing the configuration of the piezoelectric filter of FIG.
  • the piezoelectric filter 1 of this embodiment includes a ceramic base 2, two first and second piezoelectric filter elements 3 and 4 housed in the base 2, and a lid 5 that hermetically seals the base 2. It has.
  • the lid 5 is made of a metal plate such as Kovar.
  • the base 2 and the lid 5 constitute a package that accommodates both piezoelectric filter elements 3 and 4.
  • the base 2 of this embodiment is composed of a ceramic multilayer substrate whose base material is alumina or the like.
  • the base 2 includes a flat lower layer 2a having a substantially rectangular shape in plan view, a middle layer 2b constituting a step portion formed on the lower layer 2a, and an upper layer 2c constituting a frame portion formed on the middle layer 2b. It is a layer structure.
  • the three layers 2a to 2c constitute a rectangular storage recess 6 having a stepped portion for storing and holding the first and second piezoelectric filter elements 3 and 4.
  • the piezoelectric filter 1 of this embodiment is a small piezoelectric filter, the size of the base 2 is, for example, 6.0 mm ⁇ 3.5 mm, and the combined height of the base 2 and the lid 5 is, for example, 1 0.0 mm.
  • the first and second piezoelectric filter elements 3 and 4 include first and second piezoelectric substrates 7 and 8 having a rectangular shape in a plan view made of, for example, an AT-cut quartz plate.
  • One earth pad 11 is formed.
  • a second input pad 12, a second output pad 13, and a second ground pad 14 for holding the second piezoelectric substrate 8 in an electromechanical manner are formed.
  • the first piezoelectric substrate 7 having a rectangular shape in plan view has three corners of the rectangle held on the first input pad 9, the first output pad 10 and the first ground pad 11 of the base 2 by the conductive adhesive 15.
  • the Similarly, the rectangular corners of the second piezoelectric substrate 8 are held by the conductive adhesive 15 on the second input pad 12, the second output pad 13, and the second ground pad 14.
  • first and second shield electrodes 22 and 23 formed on the surface of the lower layer 2a of the base 2 constituting the inner bottom surface of the package, and input electrodes 71 and 81 (described later) of the piezoelectric substrates 7 and 8, respectively.
  • the facing gap G between the output electrodes 72 and 82 can be stably maintained within a required range. Further, the influence of the stress applied from the base 2 can be reduced as compared with the case where the piezoelectric substrates 7 and 8 are held by all four corners.
  • the first input pad 9 as the input electrode pad and the second output pad 13 as the output electrode pad are diagonally opposed corner portions of the rectangular storage recess 6 in plan view, That is, they are formed at the most distant positions.
  • a rectangular input electrode 71 and an output electrode 72 are respectively formed in parallel with a gap on the back surface (lower surface) which is one main surface of the first piezoelectric substrate 7 of the first piezoelectric filter element 3. These electrodes 71 and 72 are drawn out to the opposite corners of the first piezoelectric substrate 7 and are electrically connected to the first input pad 9 and the first output pad 10 by the conductive adhesive 15 that has been primed, respectively. It is connected. Since the input electrode 71 and the output electrode 72 of the first piezoelectric substrate 7 are drawn to the opposite corners of the rectangular first piezoelectric substrate 7, that is, the farthest position of the rectangle, the electrodes 71 and 72 are mutually connected. As a result, the guaranteed attenuation can be increased.
  • the input electrode 71 of the first piezoelectric substrate 7 is drawn out and electrically connected by the conductive adhesive 15 to the first input pad 9 at one of the opposing corners of the rectangular storage recess 6 in plan view. ing.
  • a common electrode 73 which is a rectangular ground electrode corresponding to the input electrode 71 and the output electrode 72 is formed on the surface (upper surface) which is the other main surface of the first piezoelectric substrate 7.
  • the common electrode 73 is drawn out to the other corner of the first piezoelectric substrate 7 and is electrically connected to the first ground pad 11 by the conductive adhesive 15 that is undercoated and overcoated.
  • the second piezoelectric substrate 8 of the second piezoelectric filter element 4 similarly to the first piezoelectric substrate 7, rectangular input electrodes 81 and output electrodes 82 are formed on the back surface, respectively. These electrodes 81 and 82 are drawn out to opposite corners of the second piezoelectric substrate 8 and are electrically connected to the second input pad 12 and the second output pad 13 by the undercoat conductive adhesive 15. ing. Since the input electrode 81 and the output electrode 82 of the second piezoelectric substrate 8 are drawn out to the opposite corners of the rectangular second piezoelectric substrate 8, that is, the farthest position of the rectangle, the electrodes 81 and 82 are mutually connected. As a result, the guaranteed attenuation can be increased.
  • the output electrode 82 of the second piezoelectric substrate 8 is drawn out and electrically connected by the conductive adhesive 15 to the second output pad 13 at the other corner of the opposite corner of the storage recess 6 that is rectangular in plan view. ing.
  • a common electrode 83 that is a rectangular ground electrode corresponding to the input electrode 81 and the output electrode 82 is formed on the surface of the second piezoelectric substrate 8.
  • the common electrode 83 is drawn out to the other corner of the second piezoelectric substrate 8 and is electrically connected to the second ground pad 14 by a conductive adhesive 15 that is undercoated and overcoated.
  • the piezoelectric substrates 7 and 8 are spaced apart and arranged in the base 2 so that the output electrode 72 of the first piezoelectric substrate 7 and the input electrode 81 of the second piezoelectric substrate 8 are close to each other.
  • the piezoelectric filter elements 3 and 4 are reduced in size while suppressing the influence of each other.
  • first piezoelectric substrate 7 having a rectangular shape in plan view, two opposite corners thereof are held on the first input pad 9 and the first output pad 10 by the undercoat conductive adhesive 15.
  • a corner portion between the two corner portions of the first piezoelectric substrate 7 is held on the first ground pad 11 by a conductive adhesive 15 that is undercoated and overcoated.
  • the two opposite corners of the first piezoelectric substrate 7 are held by the undercoat conductive adhesive 15, respectively, and between the two corners. Since the first ground pad 11 is held by the overcoated conductive adhesive 15 in addition to the undercoated conductive adhesive 15, it is possible to effectively prevent the first piezoelectric substrate 7 from tilting. .
  • the second piezoelectric substrate 8 two opposite corners are held on the second input pad 12 and the second output pad 13 by the undercoat conductive adhesive 15. Since the corner between the two corners of the second piezoelectric substrate 8 is held on the second ground pad 14 by the conductive adhesive 15 that is undercoated and overcoated, the second piezoelectric substrate 8 is inclined. It can be effectively prevented.
  • the six first to sixth external connection terminals 16 to 21 for surface mounting shown in FIG. 4 are independently formed on the outer bottom surface of the base 2 of the piezoelectric filter 1. That is, the first to sixth external connection terminals 16 to 21 of the base 2 are separate terminals separated from each other. These external connection terminals 16 to 21 correspond to the pads 9 to 14 of the storage recess 6 of the base 2 and are individually connected via wiring (wiring patterns, vias, etc.) not shown formed in the base 2. Are electrically connected to the corresponding pads 9 to 14, respectively. Further, these external connection terminals 16 to 21 are formed at positions below the pads 9 to 14 individually corresponding to the storage recess 6 of the base 2.
  • the electrodes 71 to 73 and 81 to 83 of the first and second piezoelectric substrates 7 and 8 are connected to the pads 9 to 14 of the housing recess 6 of the base 2, respectively.
  • the sixth external connection terminals 16 to 21 are connected to the corresponding electrodes 71 to 73 and 81 to 83 of the first and second piezoelectric substrates 7 and 8 via the corresponding pads 9 to 14 individually. ing.
  • the input electrode 71 of the first piezoelectric substrate 7 and the first external connection terminal 16 are connected via a first input pad 9 (not shown), and the first piezoelectric substrate is connected.
  • the common electrode 73 of the substrate 7 and the second external connection terminal 17 are connected via the first ground pad 11 (not shown), and the output electrode 72 of the first piezoelectric substrate 7 and the third external connection terminal 18 are connected.
  • the output electrode 82 of the second piezoelectric substrate 8 and the fourth external connection terminal 19 are connected via the second output pad 13 (not shown), and the common electrode 83 of the second piezoelectric substrate 8 and the fifth external connection terminal 19 are connected.
  • the connection terminal 20 is connected via a second ground pad 14 (not shown), and the input electrode 81 of the second piezoelectric substrate 8 and the sixth external connection terminal 21 are connected to the second input pad 12 (not shown). ) Is connected through.
  • the input electrodes 71 and 81, the output electrodes 72 and 82, and the common electrodes 73 and 83 of the piezoelectric substrates 7 and 8 are independent of the first and sixth external connection electrodes 16 and 21, the third and third The four external connection terminals 18 and 19 and the second and fifth external connection terminals 17 and 20 are individually connected. That is, since the electrodes 71 to 73 and 81 to 83 of the piezoelectric substrates 7 and 8 are individually connected to the independent external connection terminals 16 to 21, the electrodes 71 to 73 of the piezoelectric substrates 7 and 8 are connected. , 81 to 83 can be prevented from affecting each other, and the guaranteed attenuation can be increased.
  • one piezoelectric filter element 3 (or 4) can be adjusted independently without being influenced by the other piezoelectric filter element 4 (or 3).
  • the first external connection terminal 16 to which the input electrode 71 of the first piezoelectric substrate 7 is connected is an external connection terminal for input of the piezoelectric filter 1, that is, an input terminal, and the output electrode 82 of the second piezoelectric substrate 8 is
  • the connected fourth external connection terminal 19 is an external connection terminal for output of the piezoelectric filter 1, that is, an output terminal.
  • the first external connection terminal 16 for input is formed on the outer bottom surface below the first input pad 9 at one opposite corner of the rectangular storage recess 6 in plan view, and the fourth external connection terminal for output. 19 is formed on the outer bottom surface below the second output pad 13 at the other opposing corner of the storage recess 6.
  • the second external connection terminal 17 connected to the common electrode 73 of the first piezoelectric substrate 7 and the fifth external connection terminal 20 connected to the common electrode 83 of the second piezoelectric substrate 8 are grounded as GND terminals.
  • the sixth external connection terminal 21 connected to the input electrode 81 of the second piezoelectric filter element 4 is commonly connected to the coupling capacitor C1.
  • the output electrode 72 of the first piezoelectric filter element 3 and the input electrode 81 of the second piezoelectric filter element 4 are connected to each other, and two two-pole type first and second piezoelectric filter elements 3 and 4 are cascaded.
  • a connected 4-pole type piezoelectric filter 1 is configured.
  • the input electrode 71 of the first piezoelectric substrate 7 is drawn out to one opposite corner of the rectangular storage recess 6 and connected to the first input pad 9 via the conductive adhesive 15.
  • the first input pad 9 is electrically connected to the input external connection terminal 16 on the outer bottom surface below the first input pad 9.
  • the output electrode 82 of the second piezoelectric substrate 8 is drawn out to the other opposite corner of the housing recess 6 and connected to the second output pad 13 via the conductive adhesive 15, and the second output pad 13.
  • the external connection terminal 19 for output on the lower outer bottom surface is connected.
  • the first input pad 9 and the external connection terminal 16 for input of the piezoelectric filter 1 and the second output pad 13 and the external connection terminal 19 for output are arranged in the rectangular storage recess 6 of the base 3. Since it arrange
  • the aspect ratio of the rectangular input / output electrodes 71 and 72 of the first piezoelectric filter element 3 and the aspect ratio of the rectangular input / output electrodes 81 and 82 of the second piezoelectric filter element 4 are different. As shown in FIG. 2, since the input / output electrodes 71 and 72 have a shape close to a rectangle and the input / output electrodes 81 and 82 have a shape close to a square, spurious can be suppressed.
  • the electrode shapes of both piezoelectric filter elements 3 and 4 may be the same.
  • the first and second shield electrodes 22 and 23 corresponding to the first and second piezoelectric substrates 7 and 8 are formed on the flat surface of the flat lower layer 2a of the base 2 constituting the inner bottom surface of the package. Is formed.
  • Each of the shield electrodes 22 and 23 is configured by forming a gold plating layer on the upper surface of a metallized layer made of tungsten or the like.
  • the shield electrodes 22 and 23 are connected in common to the second and fifth external connection terminals 17 and 20 which are GND terminals via wirings (wiring patterns, vias, etc.) (not shown) formed inside the base 2. Grounded.
  • the shield electrodes 22 and 23 are opposed to at least the input electrodes 71 and 81 and the output electrodes 72 and 82 on the back surface of the piezoelectric substrates 7 and 8 with a facing gap G therebetween.
  • the first shield electrode 22 overlaps at least the input electrode 71 and the output electrode 72 of the first piezoelectric substrate 7 in a plan view, while the second shield electrode 23 overlaps at least the input electrode 81 of the second piezoelectric substrate 8. And the output electrode 82 so as to overlap with each other in plan view.
  • the first shield electrode 22 is continuously formed so as to face not only both the electrodes 71 and 72 of the first piezoelectric substrate 7 but also a spaced area between the input electrode 71 and the output electrode 72. Is done.
  • the second shield electrode 23 is continuously formed so as to face not only both the electrodes 81 and 82 of the second piezoelectric substrate 8 but also a spaced area between the input electrode 81 and the output electrode 82. Has been.
  • the area of the region where the first shield electrode 22 is formed is the sum of the area of the region where the input electrode 71 of the first piezoelectric substrate 7 is formed and the area of the region where the output electrode 72 is formed. Greater than total area.
  • the area of the region where the second shield electrode 23 is formed is the sum of the area of the region where the input electrode 81 of the second piezoelectric substrate 8 is formed and the area of the region where the output electrode 82 is formed. Greater than the total area.
  • the area of the region where the first shield electrode 22 is formed is preferably, for example, within about 4 times the area of the region where the input electrode 71 and the output electrode 72 of the first piezoelectric substrate 7 are formed.
  • the area of the region where the second shield electrode 23 is formed is preferably within about four times the area of the region where the input electrode 81 and the output electrode 82 of the second piezoelectric substrate 8 are formed.
  • the shield electrodes 22 and 23 are thus opposed to at least the input electrodes 71 and 81 and the output electrodes 72 and 82 of the piezoelectric substrates 7 and 8, respectively, the input electrodes 71 and 81 and the output electrodes 72 and 82 As a result, it is possible to prevent the electromagnetic coupling between the two and increase the guaranteed attenuation.
  • Figure 5 is a plan view of the area of the region where the shield electrode 22 1, 23 1 are formed corresponds to Figure 2 of the piezoelectric filter 1 1 a narrow comparative example.
  • the first shield electrode 22 1, the output electrode 72 of the first piezoelectric substrate 7 facing but not opposed to the input electrode 71.
  • the second shield electrode 23 1 faces the input electrode 81 of the second piezoelectric substrate 8 but does not face the output electrode 82.
  • Piezoelectric filter 1 1 This comparative example is directed to half the area for forming the shield electrode in comparison with the piezoelectric filter 1 of the embodiment shown in FIG.
  • the piezoelectric filter 1 1 is the same as the piezoelectric filter 1 of the embodiment shown in FIG. 2 except for the formation region of the shield electrodes 22 1 and 23 1 , and each of the shield electrodes 22 and 23 and each of the piezoelectric substrates 7 and 8.
  • the gap G between the input electrodes 71 and 81 and the output electrodes 72 and 82 is 250 ⁇ m.
  • Figure 6 is a diagram showing filter characteristics of the piezoelectric filter 1 1 of the comparative example, the horizontal axis represents the frequency (kHz), the vertical axis represents guaranteed attenuation amount (dB), respectively, the center frequency f 0 73.35 MHz.
  • the required guaranteed attenuation for example, 90 dB or more cannot be satisfied in the frequency range from the center frequency f 0 (73.35 MHz) to ⁇ 4500 kHz.
  • each shield electrode 22 1, 23 1, the piezoelectric filter 2 1 of Figure 5 which is not only opposite to one electrode 72,81 of the respective piezoelectric substrates 7,8, each shield electrode 22 1, 23 1 Electromagnetic coupling generated between the input electrodes 71 and 81 and the output electrodes 72 and 82 in a region not facing the input electrodes 71 and 81 and the output electrodes 72 and 82 of the piezoelectric substrates 7 and 8 is sufficiently obtained. It cannot be suppressed, and the guaranteed attenuation characteristic is lowered.
  • the shield electrodes 22 and 23 face at least the input electrodes 71 and 81 and the output electrodes 72 and 82 of the piezoelectric substrates 7 and 8, respectively.
  • the gap G between the shield electrodes 22 and 23 and the input electrodes 71 and 81 and the output electrodes 72 and 82 of the piezoelectric substrates 7 and 8 is set to 100 ⁇ m or more. Yes.
  • the facing gap G is less than 100 ⁇ m, the floor level (background noise level) of the guaranteed attenuation characteristic is inclined, and there may be a band that cannot satisfy the required guaranteed attenuation characteristic.
  • the opposing gap G is preferably less than 360 ⁇ m in order to effectively suppress the electromagnetic coupling generated between the input electrodes 71 and 81 and the output electrodes 72 and 82 of the piezoelectric substrates 7 and 8. . That is, the facing gap G is not less than 100 ⁇ m and less than 360 ⁇ m, preferably not less than 200 ⁇ m and not more than 300 ⁇ m.
  • the base 2 2 a two-layer structure, the opposing gap G of less than 100 [mu] m, specifically, is a longitudinal sectional view corresponding to Figure 1 of the piezoelectric filter 1 second comparative example in which 40 [mu] m.
  • Figure 8 is a graph showing the filter characteristics of the piezoelectric filter 1 2 of the comparative example, the horizontal axis represents the frequency (kHz), the vertical axis represents guaranteed attenuation amount (dB), respectively, the center frequency f 0 73.35 MHz.
  • An amount, for example, about 90 dB or more can be satisfied.
  • the opposing gap G between the shield electrodes 22 and 23 and the input electrodes 71 and 81 and the output electrodes 72 and 82 of the piezoelectric substrates 7 and 8 is close to 40 ⁇ m, which is less than 100 ⁇ m, the opposing gap Since G is too narrow, as shown in FIG. 8, the floor level of the guaranteed attenuation characteristic is inclined as shown by the broken line L1. Since the inclination angle varies, a band in which the required guaranteed attenuation amount cannot be satisfied is generated.
  • FIG. 9 is a diagram showing filter characteristics of a comparative piezoelectric filter in which the facing gap G is 360 ⁇ m.
  • the piezoelectric filter of the comparative example showing the filter characteristics of FIG. 9 is the same as the embodiment shown in FIG. 1 except that the facing gap G is widened to 360 ⁇ m, and the shield electrodes 22 and 23 are respectively connected to the piezoelectric substrates 7. , 8 are opposed to the input electrodes 71, 81 and the output electrodes 72, 82.
  • the required guaranteed attenuation amount for example, 90 dB or more in the frequency range from the center frequency f 0 (73.35 MHz) to ⁇ 4500 kHz. Can't meet.
  • each shield electrode 22, 23 faces at least each input electrode 71, 81 and each output electrode 72, 82 of each piezoelectric substrate 7, 8.
  • the facing gap G is set to 100 ⁇ m or more and less than 360 ⁇ m.
  • FIG. 10 is a diagram showing filter characteristics of the piezoelectric filter 1 of the example in which the facing gap G is 250 ⁇ m.
  • the shield electrodes 22 and 23 are opposed to at least the input electrodes 71 and 81 and the output electrodes 72 and 82 of the piezoelectric substrates 7 and 8, respectively, and the shield electrodes 22 and 23. Since the opposing gap G between each of the input electrodes 71 and 81 and each of the output electrodes 72 and 82 is an appropriate opposing gap without being too close, the gap between the input electrodes 71 and 81 and the output electrodes 72 and 82 As shown in the area surrounded by the broken line in FIG. 10, the required guaranteed attenuation amount in the frequency range from the center frequency f 0 (73.35 MHz) to ⁇ 4500 kHz. For example, it can satisfy about 90 dB or more and can be improved to about 100 dB. Further, the floor level of the guaranteed attenuation characteristic is flat without being inclined.
  • FIG. 11 is a diagram showing the filter characteristics of the piezoelectric filter 1 of another example in which the facing gap G is 220 ⁇ m.
  • the piezoelectric filter of this embodiment can satisfy the required guaranteed attenuation amount, for example, about 90 dB or more in the frequency range from the center frequency f 0 (73.35 MHz) to ⁇ 4500 kHz, and has a guaranteed attenuation characteristic floor.
  • the level is flat without inclining.
  • a quartz substrate is used as the piezoelectric substrate, but a ceramic substrate or a polycrystalline substrate having piezoelectric characteristics may be used.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

Sur la surface interne d'un boîtier dans lequel sont logés deux éléments de filtre piézoélectrique, une électrode de blindage faisant face aux deux électrodes d'une électrode d'entrée et d'une électrode de sortie d'un substrat piézoélectrique de chacun des éléments de filtre piézoélectrique est formée. Un espace entre les deux électrodes du substrat piézoélectrique et l'électrode de blindage sur la surface interne du boîtier est réglé à 100 µm ou plus.
PCT/JP2019/001479 2018-02-02 2019-01-18 Filtre piézoélectrique Ceased WO2019150992A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2019569000A JP7205497B2 (ja) 2018-02-02 2019-01-18 圧電フィルタ
CN201980007145.5A CN111557076B (zh) 2018-02-02 2019-01-18 压电滤波器

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018017175 2018-02-02
JP2018-017175 2018-02-02

Publications (1)

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WO2019150992A1 true WO2019150992A1 (fr) 2019-08-08

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CN111557076A (zh) 2020-08-18
CN111557076B (zh) 2024-04-16

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