JP2006050537A - Piezoelectric resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor built-in type piezoelectric resonator improved in thinness, smallness, and reliability. <P>SOLUTION: The piezoelectric resonator has a pair of vibration electrodes to be each bonded on one of both main surfaces of a piezoelectric substrate opposing to each other, and a pair of sealing substrates to be each mounted via a frame surrounding an opposing area in which an electrostatic capacitor is formed on one of the substrates, wherein one of the sealing substrates is made of ceramic material having specific inductive capacity of 200 to 5,000 while the other is made of a resin material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric resonator, and more particularly to a piezoelectric resonator of a type having a built-in capacitance used for an oscillation circuit, a filter circuit, and the like.

  As a conventional capacitor built-in type piezoelectric resonator, for example, one having a structure shown in FIG. 8 is known (see, for example, Patent Document 1).

  FIG. 8A shows a capacitor substrate 103 having a concave portion 105 for forming a vibration space on the upper and lower surfaces of the piezoelectric substrate 101 having the vibration electrode 102 at the center of the upper and lower surfaces at a position facing the vibration electrode 102 of the piezoelectric substrate 101. 1 is a cross-sectional view of a built-in capacitor type piezoelectric resonator formed by forming a sealed vibration space between a piezoelectric substrate 101 and a capacitor substrate 103 by bonding them together with a sealing material 104. FIG.

  In this structure, the area and height of the vibration space are determined in advance by the area and depth of the recess 105 of the capacitor substrate 103, and the thickness of the sealing material 104 can be reduced. Therefore, since the distance between the vibration electrode 102 and the sealing material 104 and the capacitor substrate 103 can be maintained, damping of vibration due to contact with the vibration electrode 102 can be effectively prevented, and the reliability is excellent.

  In FIG. 8B, a sealed vibration space is formed on the upper and lower surfaces of the piezoelectric substrate 101 having the vibration electrode 102 at the center of the upper and lower surfaces via a sealing material 104 surrounding the vibration electrode 102. 3 is a cross-sectional view of a built-in capacitor type piezoelectric resonator formed by bonding a flat capacitor substrate 103. FIG.

  In this structure, an uncured sealing material 104 is applied to the upper and lower surfaces of the piezoelectric substrate 101 so as to surround the vibration region of the vibration electrode 102, and then the capacitor substrate 103 is placed thereon, and then the sealing material 104. It is manufactured by curing. The product of this structure can be reduced in height because the height of the vibration space can be made the thickness of the sealing material 104, and it is not necessary to form a recess in the central portion of the capacitor substrate 103, thereby man-hours. It can be reduced.

In either structure, a piezoelectric resonant element is formed by the piezoelectric substrate 101 made of piezoelectric ceramic and the vibrating electrodes 102 formed on the upper and lower surfaces thereof, and the capacitor substrate 103 made of dielectric ceramic and the capacitance formation The electrode 106 and the external terminal electrodes 107, 108, 109 form a capacitance used in an oscillation circuit or the like together with the piezoelectric resonance element.
JP-A-3-247010 (FIG. 1)

  However, in the product having the structure shown in the cross-sectional view of FIG. 8A, it is necessary to form the recess 105 in the capacitor substrate 103 in advance, and there is a problem that an extra process is required. Further, since it is difficult to thinly process a ceramic having poor elasticity and toughness without causing cracks or cracks, the thickness of the capacitor substrate 103 is increased, and thus the overall thickness of the built-in capacitor type piezoelectric resonator is also increased. There was also a problem that it was not possible to fully respond to the recent demands for lighter, thinner and smaller electronic components.

  Further, in the product having the structure shown in the cross-sectional view of FIG. 8B, the step of forming the recess 105 in the capacitor substrate 103 is unnecessary, but the problem that the thickness of the capacitor substrate 103 cannot be reduced cannot be solved. That is, cracks and cracks are generated when processing a flat thin ceramic substrate, and there is a limit to producing a thin ceramic substrate with a high yield. In addition, even when trying to bond together on a collective substrate and then divide into individual pieces to improve productivity, in addition to the cracks and cracks described above, warping occurs in the processing of a large collective substrate, and the piezoelectric substrate and There is also a problem that the bonding / sealing of the substrate becomes incomplete, and there is a limit to the batch processing on the collective substrate.

  The present invention has been devised in view of the above problems, and an object of the present invention is to provide a capacitor built-in type piezoelectric resonator that is reduced in thickness without impairing mechanical strength.

In the piezoelectric resonator of the present invention, a pair of vibration electrodes disposed so as to partially face each other through the piezoelectric substrate is attached to both main surfaces of the piezoelectric substrate, and the opposing region of the vibration electrode is surrounded. A piezoelectric resonator formed by attaching a pair of sealing substrates through a frame body, and forming a capacitance electrically connected to the vibration electrode on one of these sealing substrates,
One of the pair of sealing substrates is made of a ceramic material having a relative dielectric constant of 200 to 5000, and the other is made of a resin material.

  The piezoelectric resonator of the present invention may be configured such that a resin layer is interposed between the one sealing substrate and the frame on the one sealing substrate side with respect to the piezoelectric substrate. good.

  Furthermore, the piezoelectric resonator of the present invention may be configured such that the other sealing substrate and the resin layer are made of the same material and have substantially the same thickness.

  Furthermore, in the piezoelectric resonator of the present invention, glass fibers may be embedded in the other sealing substrate.

  Furthermore, in the piezoelectric resonator of the present invention, the resin material used for the other sealing substrate and the frame may be made of a similar resin material.

  Furthermore, in the piezoelectric resonator of the present invention, the other sealing substrate side of the pair of sealing substrates may be a mounting surface.

  In the piezoelectric resonator of the present invention, a pair of vibration electrodes disposed so as to partially face each other through the piezoelectric substrate is attached to both main surfaces of the piezoelectric substrate, and the opposing region of the vibration electrode is surrounded. A pair of sealing substrates are attached via a frame body, and a capacitance that is electrically connected to the vibration electrode is formed on one of the sealing substrates, and the pair of sealing substrates One of these is made of a ceramic material having a relative dielectric constant of 200 to 5000, and the other is made of a resin material. Therefore, by using a ferroelectric ceramic substrate as one sealing substrate, the formation of a large capacitance is facilitated, the strength against external stress and the like is improved, and the stress applied to the piezoelectric substrate is reduced, A piezoelectric resonator having excellent reliability can be obtained. Further, since the other sealing substrate is formed of a resin substrate that is free from cracks and cracks, the thickness can be reduced, and the entire thickness of the piezoelectric resonator can also be reduced. Furthermore, a complicated process such as recess processing for forming a vibration space is not necessary, and the manufacturing process can be simplified.

  In the piezoelectric resonator of the present invention, a resin layer may be interposed between the one sealing substrate and the frame on the one sealing substrate side with respect to the piezoelectric substrate. In this case, it is possible to effectively prevent a problem that the adhesive strength between the piezoelectric substrate and the one sealing substrate is lowered due to insufficient flatness of the surfaces of the piezoelectric substrate and the one sealing substrate.

  Furthermore, in the piezoelectric resonator of the present invention, the other sealing substrate and the resin layer may be made of the same material and set to substantially the same thickness. It is possible to effectively reduce the non-uniformity of stress applied to the.

  Furthermore, in the piezoelectric resonator of the present invention, glass fiber may be embedded in the other sealing substrate, and in that case, thermal deformation of the other sealing substrate can be reduced. The contact with the piezoelectric substrate due to the deformation of the other sealing substrate can be effectively prevented, and the thickness of the frame can be further reduced.

  Furthermore, in the piezoelectric resonator of the present invention, the resin material used for the other sealing substrate and the frame may be made of a similar resin material. The familiarity between the substrate and the frame is improved, and the bonding strength between the two can be improved.

  Furthermore, the piezoelectric resonator of the present invention may be configured such that the other sealing substrate side of the pair of sealing substrates becomes a mounting surface, and in that case, the other is made of a soft and easily deformable resin material. Since it is mounted on the mounting substrate on the sealing substrate side, the stress generated by the difference in thermal expansion coefficient and elastic modulus with the mounting substrate at the time of mounting is absorbed by deformation of the other sealing substrate, and near the mounting surface Generation | occurrence | production of a crack etc. can be suppressed effectively.

  Hereinafter, a piezoelectric resonator of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an external perspective view schematically showing an example of the piezoelectric resonator of the present invention, FIG. 2 is a sectional view taken along line AA, and FIG. 3 is an exploded perspective view.

  In the figure, the piezoelectric resonator 1 has a structure in which the upper and lower surfaces of a piezoelectric substrate 21 are sandwiched between one sealing substrate 31 and the other sealing substrate 41 while forming vibration spaces 61a and 61b by frame bodies 51a and 51b. It is said that. Vibrating electrodes 22a and 22b are attached to the upper and lower surfaces of the piezoelectric substrate 21 so as to partially face each other with the piezoelectric substrate 21 interposed therebetween, and the piezoelectric resonant element 20 is configured to resonate at a specific frequency. ing. In addition, internal electrodes 32a and 32b and external terminal electrodes 33a, 33b, and 33c are formed on the upper and lower surfaces of the sealing substrate 31, and a capacitance c1 is connected between the external terminal electrodes 33a and 33c. A capacitor element 30 is formed in which a capacitance c2 is formed between the terminal electrodes 33b and 33c. The vibration electrode 22a, the internal electrode 32a, and the external terminal electrode 33a are connected by the external connection electrode 71a, the vibration electrode 22b, the internal electrode 32b, and the external terminal electrode 33b are connected by the external connection electrode 71b. By connecting the external terminal electrode 33c to the external connection electrode 71c, the piezoelectric resonant element 20 and the capacitor element 30 are electrically connected, and the built-in capacitive piezoelectric resonator 1 represented by the equivalent circuit shown in FIG. Is configured.

The piezoelectric substrate 21 is composed of a piezoelectric ceramic material such as lead zirconate titanate (PZT) or lead titanate (PT), or a piezoelectric single crystal material such as quartz (SiO ₂ ) or lithium niobate (LiNbO ₃ ). A rectangular substrate having a horizontal length of several mm × several mm and a thickness of several tens of μm to several mm. When the piezoelectric substrate 21 is made of a ceramic material, the raw material powder is pressed by adding a binder, or the raw material powder is mixed and dried by using a ball mill together with water and a dispersant, and the binder, solvent, plasticizer, etc. To form a sheet by a method such as molding by the doctor blade method, and after baking at a peak temperature of 1100 to 1400 ° C. for several tens of minutes to several hours to form a substrate, for example, to a temperature of 60 to 150 ° C. in the thickness direction A desired piezoelectric characteristic is imparted by applying a polarization treatment by applying a voltage of 3 to 15 kV / mm. When the piezoelectric substrate 21 is made of a piezoelectric single crystal material, the piezoelectric substrate 21 has desired piezoelectric characteristics by cutting an ingot (base material) of the piezoelectric single crystal material that becomes the piezoelectric substrate 21 in a predetermined crystal direction. The piezoelectric substrate 21 can be obtained.

  A pair of vibrating electrodes 22 a and 22 b are formed near the center of the upper and lower surfaces of the piezoelectric substrate 21. The pair of vibration electrodes 22a and 22b are integrated with the piezoelectric substrate 21 to form elements such as a piezoelectric resonator, a piezoelectric vibrator, and a piezoelectric filter, and are gold, silver, copper, chromium, nickel, tin, and lead. It is a highly conductive metal such as aluminum, and is formed by coating and baking by a PVD method such as vacuum deposition, a sputtering method, or a thick film printing method. Alternatively, a metal such as chromium (Cr) having good adhesion to the ceramic material may be deposited on the piezoelectric substrate 21 in advance, and the metal may be deposited thereon.

  The shape of the vibrating electrode 22 is a circular shape or a quadrangular shape with a length in the vertical and horizontal directions of several tens of μm to several mm, and its size and position are determined by resonance characteristics and other desired electrical characteristics. The vibrating electrode 22 has a thickness of several μm to several tens of μm, and is determined by a resonance frequency or the like. Furthermore, the vibration electrode 22 may be a divided electrode in which a plurality of electrodes are formed on the upper surface or the lower surface of the piezoelectric substrate 21. A part of the vibration electrode 22 is drawn toward the outer periphery of the piezoelectric substrate 21. For example, the vibration electrode 22a is connected to the external terminal electrode 33a via the external connection electrode 71a, and the vibration electrode 22b is connected to the outside. Each is electrically connected to the external terminal electrode 33b via the connection electrode 71b.

  And on the upper and lower surfaces of the piezoelectric substrate 21 to which the pair of vibration electrodes 22 are attached, a pair of sealing substrates 31, via a pair of frame bodies 51a and 51b surrounding the opposing regions of the vibration electrodes 22a and 22b, 41 is adhered.

  The sealing substrate 31 forms a vibration space 61a together with the frame 51a and has a function of protecting the piezoelectric substrate 21 from an external force. Lead zirconate titanate (PZT), lead titanate (PT), and barium titanate. This is a rectangular substrate made of a ferroelectric ceramic material such as (BT) and having a length and width of several mm × several mm and a thickness of several tens of μm to several mm. This sealing substrate 31 is a method of pressing a raw material powder by adding a binder, or mixing and drying the raw material powder together with water and a dispersant using a ball mill, and adding a binder, a solvent, a plasticizer, etc., and a doctor blade method. The sheet is formed by a method such as molding by baking, and the sheet is fired at a peak temperature of 1100 to 1400 ° C. for several tens of minutes to several hours. Here, the material of the sealing substrate 31 is a ferroelectric ceramic material such as lead zirconate titanate (PZT), lead titanate (PT), or barium titanate (BT), so that the ratio of the sealing substrate 31 can be increased. Since the dielectric constant can be increased, the capacitor element 30 having a sufficiently large capacitance can be configured. Note that the relative dielectric constant of the sealing substrate 31 is desirably 200 to 5000.

  Internal electrodes 32a, 32b and external terminal electrodes 33a, 33b, 33c are formed on the upper and lower surfaces of the sealing substrate 31. The internal electrode 32 and the external terminal electrode 33 together with the sealing substrate 31 form a capacitance c1 between the external terminal electrodes 33a and 33c and a capacitance c2 between the external terminal electrodes 33b and 33c, respectively. The capacitor element 30 is formed by the same material and method as those of the vibrating electrode 22. The external terminal electrode 33 is further used for mechanical and electrical connection with a substrate on which the piezoelectric resonator 1 is mounted, and the surface thereof is Ni-Sn plated.

  The sealing substrate 41 forms a vibration space 61b together with the frame 51b, and has a function of protecting the vibration region on the upper surface of the piezoelectric substrate 21. The vertical and horizontal lengths thereof are the same as the vertical and horizontal lengths of the piezoelectric substrate 21. Although it is substantially the same, the thickness varies depending on the material, but is several tens of μm to several mm. As a material for such a sealing substrate 41, engineering plastics such as polybutylene terephthalate (PBT), and heat-resistant resins such as liquid crystal polymers and epoxy resins can be used. Polyimide resins and epoxy resins containing glass fibers can be used. By using, the thermal deformation of the sealing substrate 41 can be suppressed, and the vibration space can be easily formed. A polyimide resin sheet or an epoxy resin sheet having a glass fiber content of 30 to 80% is preferably used. In that case, 180 ° C. to 200 ° C. while applying a pressure of 0.2 MPa to 5 MPa in a vacuum of 100 Pa or less. Good bonding can be achieved by curing at a temperature of 40 ° C. for 40 minutes to 90 minutes. According to the inventor's experiment, when a polyimide resin having a glass fiber content of 32% is used, deformation (deflection) due to heating at the time of sealing substrate bonding is reduced to 40% of the polyimide resin not containing glass fiber. I was able to.

  The frame bodies 51a and 51b have a function of bonding the piezoelectric substrate 21 and the sealing substrates 31 and 41 and forming the vibration spaces 61a and 61b. The frame 51 is made of a thermosetting resin such as an epoxy resin, and is formed by, for example, applying by thick film printing and drying and curing at 80 ° C. to 200 ° C. Since the epoxy resin has a dense three-dimensional network structure, it is excellent in airtightness, and the vibration space can be hermetically sealed over a long period of time.

  Moreover, in order to adjust the viscosity and thermal expansion coefficient of the frame 51, the frame 51 may contain a filler made of ceramics such as silicon oxide. The height of the frame body 51 is preferably set so that the distance between the vibration electrode 22 and the sealing substrates 31 and 41 is 5 μm to 100 μm, and the distance between the vibration electrode 22 and the sealing substrates 31 and 41. Is more preferably 20 μm to 60 μm. When the distance between the vibration electrode 22 and the sealing substrates 31 and 41 is less than 20 μm, when an unnecessary external force is applied to the piezoelectric resonator, the sealing substrate 31 or 41 bends and comes into contact with the vibration electrode 22. If the thickness exceeds 60 μm, the thickness of the piezoelectric resonator becomes unnecessarily thick, and it tends to be difficult to reduce the thickness.

  In addition, when a pair of frame 51 consists of the same material, since the process of apply | coating the frame 51 can be unified, a man-hour can be reduced and manufacturing cost can be reduced. Alternatively, the vibration space 61 may be formed in a vacuum and the vibration electrode 22 may be sealed in a vacuum. In this case, the vibration corrosion of the vibration electrode 22 is prevented, and a more reliable piezoelectric resonator is obtained. Can do.

  On the side surface of the piezoelectric resonator 1, the external connection electrode 71a that electrically connects the vibration electrode 22a, the internal electrode 32a, and the external terminal electrode 33a, and the vibration electrode 22b, the internal electrode 32b, and the external terminal electrode 33b are electrically connected. The external connection electrode 71b connected to the external terminal electrode 33c and the external connection electrode 71c connected to the external terminal electrode 33c are formed. The external connection electrode is made by depositing a highly conductive metal such as gold, silver, copper, chromium, nickel, tin, lead, or aluminum by PVD or sputtering such as vacuum deposition, or conductive epoxy resin. Is applied by thick film printing or the like, cured at 80 ° C. to 250 ° C. and formed, and if desired, the surface is plated with Ni—Sn or the like.

  According to the embodiment described above, one sealing substrate 31 is made of a ferroelectric ceramic material such as lead zirconate titanate (PZT), lead titanate (PT), or barium titanate (BT), and the other sealing substrate 31 is sealed. The stop substrate 41 is made of a resin material. Therefore, the use of a ferroelectric ceramic substrate for the sealing substrate 31 facilitates the formation of a large capacitance, improves the strength against external stress, etc., and reduces the stress applied to the piezoelectric substrate. Piezoelectric resonators with excellent properties can be obtained. In addition, since the sealing substrate 41 is formed of a resin substrate that is free from cracks and cracks, the sealing substrate 41 can be thinned, and the entire thickness of the piezoelectric resonator can be thinned.

  When the sealing substrate 41 was a ceramic substrate similar to the sealing substrate 31, its thickness was limited to 150 μm due to strength problems such as structural defects of the ceramic, but the sealing substrate 41 contained glass fibers. By using a resin substrate, the thickness could be reduced to 28 μm, and the piezoelectric resonator 1 could be reduced by that much.

  Moreover, according to embodiment mentioned above, the sealing substrate 41 consists of an epoxy-type resin sheet or a polyimide-type resin sheet, and contains glass fiber. For this reason, even in the heat bonding step through the frame 51, the sealing substrate 41 hardly deforms due to heat. Accordingly, the deformation (sagging) in the vicinity of the central portion of the piezoelectric substrate 21 can suppress the sealing substrate 41 from falling to the piezoelectric substrate 21 side and coming into contact with the vibration electrode 22, so that the thickness of the frame 51 can be made as thin as possible. Thus, a thinner piezoelectric resonator 1 can be obtained.

  Further, according to the above-described embodiment, the ceramic substrate is connected and fixed to the mounting substrate on the sealing substrate 31 side, so that mounting strength is ensured and sufficient for shock and vibration after mounting. Reliable.

  Furthermore, according to the above-described embodiment, the capacitance c1 is formed between the external terminal electrodes 33a and 33c of the sealing substrate 31, and the capacitance c2 is formed between the external terminal electrodes 33b and 33c. ing. As a result, the two electrostatic capacitances used in the oscillation circuit and the like are formed between the piezoelectric substrate and the mounting substrate, and are unnecessary as a result of being connected to the external terminal electrode without an extra wiring. Stable oscillation can be realized without stray capacitance.

  FIG. 5 is an exploded perspective view schematically showing a piezoelectric resonator according to another embodiment of the present invention.

  A feature of this embodiment is that a resin layer 81 is inserted between the frame 51 a and the sealing substrate 31. When the thickness of the frame 51 is thin, if the flatness of the surfaces of the piezoelectric substrate 21 and the sealing substrate 31 is insufficient, it is difficult to compensate for this with the thickness of the frame 51. There may be a problem that the adhesive strength through the frame 51 is lowered, but it is effective by inserting a resin layer 81 that is easily deformed and has an appropriate thickness between the frame 51 a and the sealing substrate 31. Can be prevented.

  The vertical and horizontal lengths of the resin layer 81 are substantially the same as the vertical and horizontal lengths of the piezoelectric substrate 21 and the sealing substrate 31, and the thickness varies depending on the material, but is several tens of μm to several mm. As with the substrate 41, a heat-resistant resin such as a polyimide resin or an epoxy resin can be used. However, by using a polyimide resin or an epoxy resin containing glass fiber, thermal deformation can be suppressed and a vibration space can be easily formed. Therefore, for example, a polyimide resin sheet or an epoxy resin sheet having a glass fiber content of 30 to 80% is preferably used.

  Here, when the sealing substrate 41 and the resin layer 81 are made of the same material and have substantially the same thickness, uneven stress applied to the upper and lower surfaces of the piezoelectric substrate 21 can be reduced.

  The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the gist of the present invention.

  For example, in the above-described embodiment, the frame 51 is made of a thermosetting resin such as an epoxy resin and is applied by thick film printing. However, as with the sealing substrate 41 and the resin layer 81, glass fiber is used. It is good also as a polyimide resin, an epoxy resin, etc. which contain. In that case, what is necessary is just to thermocompression-bond using what formed the opening for ensuring a vibration space in the center part of the resin sheet containing glass fiber, for example, 0.2 MPa-in 100 Pa or less of vacuum Good bonding can be achieved by holding and curing at a temperature of 180 ° C. to 200 ° C. for 40 minutes to 90 minutes while applying a pressure of 5 MPa.

  Here, by using the same resin material for the frame 51b and the sealing substrate 41, the familiarity between the two improves, and the bonding strength can be improved.

  Further, in the piezoelectric resonator of the above-described embodiment, it is connected to and fixed to the mounting substrate on the side of the one sealing substrate 31 made of ceramic. However, as shown in FIGS. The other sealing substrate 41 side made of may be used as a mounting surface connected and fixed to the mounting substrate.

  FIG. 6 is an external perspective view showing a modified example of the piezoelectric resonator of the present invention, and FIG. 7 is a cross-sectional view taken along the line B-B ′.

  In the piezoelectric resonator 1 of the present modification, second external terminal electrodes 91a, 91b, 91c used for connection / fixation to the mounting substrate are formed on the lower surface of the other sealing substrate 41. The second external terminal electrode 91a is connected to the vibration electrode 22a, the internal electrode 32a, and the external terminal electrode 33a by the external connection electrode 71a, and the second external terminal electrode 92b is connected to the vibration electrode 22b and the internal by the external connection electrode 71b. The external connection electrode 91c is connected to the external terminal electrode 33c by the external connection electrode 71c. The external connection electrode 91c is connected to the electrode 32b and the external terminal electrode 33b.

  The second external terminal electrodes 91a, 91b, 91c are formed by the same material and forming method as the external terminal electrodes 31a, 31b, 31c.

  In the piezoelectric resonator 1 of this modification, the other sealing substrate 41 side made of a soft and easily deformable resin material is used as a mounting surface for mounting on the mounting substrate, so that the thermal expansion coefficient with the mounting substrate during mounting can be reduced. The stress generated by the difference in elastic modulus is absorbed by the deformation of the other sealing substrate 41, and the occurrence of cracks and the like near the mounting surface can be effectively suppressed.

It is a perspective view which shows typically an example of the piezoelectric resonator of this invention. FIG. 2 is a sectional view taken along line A-A ′ of FIG. 1. 1 is an exploded perspective view schematically showing a piezoelectric resonator of the present invention. It is a figure which shows the equivalent circuit of the piezoelectric resonator of this invention. It is a disassembled perspective view which shows typically the piezoelectric resonator of another form of this invention. It is an external appearance perspective view which shows typically the modification of the piezoelectric resonator of this invention. FIG. 7 is a sectional view taken along line B-B ′ in FIG. 6. It is sectional drawing which shows the conventional piezoelectric resonator typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ..... Piezoelectric resonator 21 ........ Piezoelectric substrate 22a, 22b ........ Vibration electrode 31, 41 ..... Sealing substrates 32a, 32b ..... Internal electrodes 33a, 33b, 33c ... External terminal electrodes 51a, 51b ... Frame Body 61a, 61b ... vibration space 71a, 71b, 71c ... external connection electrode 81 ... resin layer 91a, 91b, 91c ... Second external terminal electrode

Claims (6)

A pair of vibration electrodes, which are arranged so as to partially face each other through the piezoelectric substrate, are attached to both main surfaces of the piezoelectric substrate, and a pair of vibration electrodes is disposed via a frame surrounding the opposed region of the vibration electrode. A piezoelectric resonator formed by attaching a sealing substrate and forming a capacitance electrically connected to the vibration electrode on one of these sealing substrates,
One of the pair of sealing substrates is made of a ceramic material having a relative dielectric constant of 200 to 5000, and the other is made of a resin material. 2. The resin layer according to claim 1, wherein a resin layer is interposed between the one sealing substrate and the frame on the one sealing substrate side with respect to the piezoelectric substrate. Piezoelectric resonator. 3. The piezoelectric resonator according to claim 2, wherein the other sealing substrate and the resin layer are made of the same material and have substantially the same thickness. The piezoelectric resonator according to any one of claims 1 to 3, wherein a glass fiber is embedded in the other sealing substrate. 5. The piezoelectric resonator according to claim 1, wherein the resin material used for the other sealing substrate and the frame are made of a similar resin material. 6. 6. The piezoelectric resonator according to claim 1, wherein the other sealing substrate side of the pair of sealing substrates is a mounting surface.

Images