JP2011250058A - Piezoelectric vibrator and oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator and an oscillator having excellent reliability and temperature characteristics.SOLUTION: A piezoelectric vibrator 1 includes a wiring board 211, a piezoelectric vibration piece 3, and an adhesive 4 for fixing the piezoelectric vibration piece 3 to the wiring board 211. The piezoelectric vibration piece 3 includes a piezoelectric substrate 31 which performs thickness shear vibration, and a pair of excitation electrodes 32 and 33 provided to the piezoelectric substrate 31. The pair of excitation electrodes 32 and 33 are electrically connected to the wiring board 211 respectively using conductive wires 51 and 52.

Description

  The present invention relates to a piezoelectric vibrator and an oscillator.

Conventionally, a piezoelectric vibrator has been used as a reference frequency signal source used in various electronic devices and transmission communication devices (see, for example, Patent Document 1).
The piezoelectric vibrator (piezoelectric device) of Patent Document 1 includes a crystal resonator element and a package that accommodates the crystal resonator element.
The quartz resonator element includes an AT cut quartz plate and a pair of excitation electrodes for exciting the AT cut quartz plate, and one excitation electrode of the pair of excitation electrodes is one of the AT cut quartz plates. The other excitation electrode is formed on the other main surface of the AT-cut quartz plate.
In addition, the package is formed with a terminal electrically connected to one excitation electrode and a terminal electrically connected to the other excitation electrode.

In the piezoelectric vibrator of Patent Document 1, one excitation electrode of the crystal vibrator and one terminal formed on the package are electrically connected by a conductive adhesive (adhesive mixed with conductive particles such as a metal filler). The crystal resonator is fixed to the package by the conductive adhesive, and the other excitation electrode of the crystal resonator and the other terminal formed in the package are electrically connected by a bonding wire. .
Here, the conductivity of the conductive adhesive is greatly influenced by the amount and dispersion state of the conductive particles contained in the adhesive. Therefore, depending on the amount and dispersion state of the conductive particles in the conductive adhesive, the conduction between the excitation electrode and the terminal cannot be sufficiently obtained, resulting in poor conduction, the piezoelectric vibrator does not drive, or so-called A frequency jump (a phenomenon in which the frequency greatly shifts with a change in temperature) may occur.
In addition, since such a problem becomes so remarkable that the magnitude | size of a conductive adhesive becomes small, it was difficult to aim at size reduction of an apparatus with the conventional piezoelectric vibrator.

JP 2000-332572 A

  An object of the present invention is to provide a piezoelectric vibrator and an oscillator having excellent reliability and temperature characteristics.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
[Application Example 1]
The piezoelectric vibrator of the present invention includes a wiring board,
A piezoelectric vibrating piece;
An adhesive for fixing the piezoelectric vibrating piece to the wiring board;
The piezoelectric vibrating piece includes a piezoelectric substrate that performs thickness shear vibration, and a pair of excitation electrodes provided on the piezoelectric substrate,
Each of the pair of excitation electrodes is electrically connected to the wiring board by a conductive wire.
Thereby, a piezoelectric vibrator having excellent reliability and temperature characteristics can be provided. Further, it is possible to easily reduce the size while maintaining the reliability and temperature characteristics of the piezoelectric vibrator.

[Application Example 2]
In the piezoelectric vibrator of the present invention, one excitation electrode of the pair of excitation electrodes includes a first electrode portion formed on a first surface which is one main surface of the piezoelectric substrate, and the first electrode. A first terminal electrically connected to the first electrode portion, and the other excitation electrode is a second electrode opposite to the first surface of the piezoelectric substrate. A second electrode portion formed on the surface so as to face the first electrode portion via the piezoelectric substrate; and formed on the first surface and electrically connected to the second electrode portion. It is preferable that the first terminal and the second terminal are each electrically connected to the wiring board by the conductive wire.
Thereby, since the conductive wire is connected while avoiding the portion where the thickness shear vibration occurs substantially, the piezoelectric vibrating piece can be driven smoothly.

[Application Example 3]
In the piezoelectric vibrator of the present invention, when the two axes orthogonal to each other in plan view of the piezoelectric substrate are the first axis and the second axis, the first terminal and the second terminal are formed on the first surface. Provided at one end in the first axial direction and spaced apart in the second axial direction;
The adhesive preferably fixes the piezoelectric vibrating piece to the wiring board at the first terminal in the first axial direction on the second surface and the end on the second terminal side. .
Accordingly, the piezoelectric vibrating piece can be fixed while substantially avoiding the portion where thickness shear vibration occurs, so that the piezoelectric vibrating piece can be driven smoothly.

[Application Example 4]
In the piezoelectric vibrator of the present invention, the length of the adhesive in the second axial direction is l, and the length of the first electrode portion and the second electrode portion in the second axial direction is L. It is preferable that the relationship of l <L is satisfied.
Thereby, the frequency shift of the piezoelectric vibrating piece due to the environmental temperature can be suppressed, and the temperature characteristics of the piezoelectric vibrator are improved.

[Application Example 5]
In the piezoelectric vibrator according to the aspect of the invention, it is preferable that the adhesive is located between the first terminal and the second terminal in a plan view of the piezoelectric substrate.
Thereby, it is possible to prevent the driving of the piezoelectric vibrating piece from being hindered by the adhesive.

[Application Example 6]
In the piezoelectric vibrator of the present invention, the adhesive has a portion overlapping the first terminal and the second terminal in a plan view of the piezoelectric substrate,
The conductive wire that connects the first terminal and the wiring board is connected to the first terminal at a portion overlapping the adhesive of the first terminal,
It is preferable that the conductive wire connecting the second terminal and the wiring board is connected to the second terminal at a portion overlapping the adhesive of the second terminal.
Thereby, a conductive wire can be more reliably joined to the 1st terminal and the 2nd terminal.

[Application Example 7]
In the piezoelectric vibrator according to the aspect of the invention, the wiring board has a protruding portion that protrudes toward the piezoelectric substrate so as to include a portion to which the conductive wire of the first terminal is connected in a plan view of the piezoelectric substrate. It is preferable that at least one of the projecting portions projecting toward the piezoelectric substrate is included so as to include a portion to which the conductive wire of the second terminal is connected.
Thereby, a conductive wire can be more reliably joined to the 1st terminal and the 2nd terminal.

[Application Example 8]
In the piezoelectric vibrator according to the aspect of the invention, it is preferable that a separation distance between the protruding portion and the piezoelectric substrate is 20 μm or less.
Thereby, since the deformation amount of the adhesive accompanying the displacement of the piezoelectric substrate when joining the conductive wire to the first terminal and the second terminal can be reduced, the destruction of the adhesive or the piezoelectric vibrating piece Can be prevented from being detached from the adhesive.

[Application Example 9]
The oscillator of the present invention includes a substrate,
A piezoelectric vibrating piece;
An adhesive for fixing the piezoelectric vibrating piece to the substrate;
A circuit element mounted on the substrate and driving the piezoelectric vibrating piece;
The piezoelectric vibrating piece includes a piezoelectric substrate that performs thickness shear vibration, and a pair of excitation electrodes provided on the piezoelectric substrate,
Each of the pair of excitation electrodes is electrically connected to the circuit element directly or indirectly by a conductive wire.
As a result, an oscillator having excellent reliability and temperature characteristics can be provided. Further, it is possible to easily reduce the size while maintaining the reliability and temperature characteristics of the oscillator.

[Application Example 10]
In the oscillator according to the aspect of the invention, it is preferable that the circuit element is provided so as not to overlap the piezoelectric vibrating piece in a plan view of the substrate.
As a result, the oscillator can be downsized (thinned).
[Application Example 11]
In the oscillator according to the aspect of the invention, it is preferable that the circuit element and the piezoelectric vibrating piece are accommodated in the same space.
As a result, the environmental temperature (atmosphere temperature) of the piezoelectric vibrating piece and the circuit can be made substantially equal, so that the reliability of the oscillator is improved.

[Application Example 12]
In the oscillator according to the aspect of the invention, it is preferable that each of the pair of excitation electrodes is directly connected to the circuit element by the conductive wire.
This improves the reliability of the oscillator.
[Application Example 13]
In the oscillator according to the aspect of the invention, it is preferable that each of the pair of excitation electrodes is provided on the wiring board and connected to the oscillation circuit via a wiring to which the conductive wire is connected.
Thereby, the characteristics of the piezoelectric vibrating piece can be easily inspected during the manufacture of the oscillator.

1 is a plan view showing a first embodiment of a piezoelectric vibrator of the present invention. FIG. 2 is a plan view showing a piezoelectric vibrating piece included in the piezoelectric vibrator shown in FIG. 1. It is the sectional view on the AA line in FIG. It is a top view which shows 2nd Embodiment of the piezoelectric vibrator of this invention. FIG. 5 is a sectional view taken along line B-B in FIG. 4. It is a top view which shows 3rd Embodiment of the piezoelectric vibrator of this invention. It is CC sectional view taken on the line in FIG. It is a figure for demonstrating the function of the protrusion part shown in FIG. It is a top view which shows 4th Embodiment of the piezoelectric vibrator of this invention. FIG. 10 is a sectional view taken along line DD in FIG. 9. FIG. 10 is a plan view showing a modification of the piezoelectric vibrator shown in FIG. 9. It is a top view which shows suitable embodiment of the oscillator of this invention. It is the EE sectional view taken on the line in FIG. It is a top view which shows other embodiment of the oscillator of this invention.

Hereinafter, a piezoelectric vibrator and an oscillator of the present invention will be described in detail based on embodiments shown in the accompanying drawings.
<First Embodiment>
First, a first embodiment of the piezoelectric vibrator of the present invention will be described.
FIG. 1 is a plan view showing a first embodiment of the piezoelectric vibrator of the present invention, FIG. 2 is a plan view showing a piezoelectric vibrating piece included in the piezoelectric vibrator shown in FIG. 1, and FIG. It is A sectional view. In the following description, the upper side in FIGS. 1 and 2 is referred to as “upper”, the lower side as “lower”, the left side as “left”, and the right side as “right”. Further, in the following, as shown in FIG. 1, in a plan view of the pressure vibrator, three axes orthogonal to each other are an x-axis (first axis), a y-axis (second axis), and a z-axis (third axis). ), And a plane including the x-axis and the y-axis is a plane parallel to the main surface of the piezoelectric vibrating piece. A direction parallel to the x-axis is referred to as an “x-axis direction”, a direction parallel to the y-axis is referred to as a “y-axis direction”, and a direction parallel to the z-axis is referred to as a “z-axis direction” (another figure). The same applies to.
As shown in FIG. 1, the piezoelectric vibrator 1 includes a package 2, a piezoelectric vibrating piece 3 accommodated in the package 2, and one adhesive 4 that fixes the piezoelectric vibrating piece 3 to the package. . Hereinafter, each of these components will be described sequentially.

[Crystal vibrating piece]
2A is a plan view of the piezoelectric vibrating piece 3 viewed from one side (the lid 22 side described later), and FIG. 2B is a plan view of the piezoelectric vibrating piece 3 on the other side (a wiring substrate 211 side described later). It is the top view seen from. As shown in FIGS. 2A and 2B, the piezoelectric vibrating reed 3 includes a piezoelectric substrate 31 having a plate shape whose plan view is rectangular (rectangular), and a pair of excitation electrodes 32 formed on the piezoelectric substrate 31. , 33.

  The piezoelectric substrate 31 is a quartz base plate that mainly performs thickness shear vibration. In the present embodiment, a quartz base plate cut at a cut angle called AT cut is used as the piezoelectric substrate 31. The AT cut is a principal surface obtained by rotating a plane (Y plane) including the X axis and the Z axis, which are crystal axes of quartz, about 35 degrees 15 minutes around the X axis in the counterclockwise direction from the Z axis. The main surface including the X-axis and the Z′-axis) is cut out. In the piezoelectric substrate 31 having such a configuration, the longitudinal direction of the piezoelectric substrate 31 coincides with the X axis that is the crystal axis of the crystal.

The excitation electrode 32 includes an electrode portion (first electrode portion) 321 formed on the upper surface (first surface) 311 of the piezoelectric substrate 31 and a bonding pad (first electrode) formed on the upper surface 311 of the piezoelectric substrate 31. Terminal) 322, and wiring 323 for electrically connecting the electrode portion 321 and the bonding pad 322.
The electrode portion 321 is formed so as to exclude the right end portion in the x-axis direction of the upper surface 311 of the piezoelectric substrate 31. Moreover, the planar view shape of the electrode part 321 is a rectangle (rectangle), and the longitudinal direction corresponds to the x-axis. The bonding pad 322 is formed at the right end portion in the x-axis direction and the upper end portion in the y-axis direction of the upper surface 311 of the piezoelectric substrate 31, that is, at the corner portion located at the upper right of the upper surface 311.

On the other hand, the excitation electrode 33 includes an electrode part (second electrode part) 331 formed on the lower surface (second surface) 312 of the piezoelectric substrate 31 and a bonding pad (second electrode) formed on the upper surface 311 of the piezoelectric substrate 31. Terminal 332 and wiring 333 for electrically connecting the electrode portion 331 and the bonding pad 332.
The electrode portion 331 is formed so as to exclude the right end portion in the x-axis direction of the lower surface 312 of the piezoelectric substrate 31 and has a rectangular (rectangular) shape in plan view. The electrode portion 331 is formed so as to face the electrode portion 321 with the piezoelectric substrate 31 interposed therebetween, and has substantially the same planar view shape as the electrode portion 321. That is, the outlines of the electrode portions 321 and 331 coincide with each other in a plan view of the piezoelectric substrate 31 (a plan view including the x axis and the y axis). The bonding pad 332 is formed at the right end portion in the x-axis direction and the lower end portion in the y-axis direction of the upper surface 311 of the piezoelectric substrate 31, that is, at the lower left corner, and is separated from the bonding pad 322 in the y-axis direction. Side by side.

  For example, the excitation electrodes 32 and 33 are formed by depositing a nickel (Ni) or chromium (Cr) underlayer on the piezoelectric substrate 31 by vapor deposition or sputtering, and then depositing gold ( An Au) electrode layer can be formed and then patterned into a desired shape using photolithography and various etching techniques. Thus, by forming the base layer, the adhesiveness between the piezoelectric substrate 31 and the electrode layer is improved, and the highly reliable piezoelectric vibrating piece 3 is obtained. Note that the configuration of the excitation electrodes 32 and 33 is not limited to this. For example, the underlayer may be omitted, or the constituent material may be other conductive materials (for example, silver (Ag), copper). (Various metal materials such as (Cu), tungsten (W) and molybdenum (Mo)).

[package]
As shown in FIG. 3, the package 2 includes a base 21 and a lid 22 that closes the recess opening of the base 21.
The base 21 is configured by a laminated body of a plate-like wiring board 211 and a frame-like frame member 212, thereby forming a recess that opens to the upper side (the lid 22 side) substantially at the center of the base 21. .

The wiring substrate 211 is, for example, a substrate obtained by patterning electrodes and wiring on an insulating ceramic substrate. Such a wiring board 211 fixes the piezoelectric vibrating piece 3 and electrically connects the piezoelectric vibrating piece 3 to, for example, an IC chip (not shown) (a semiconductor circuit element including at least a circuit (oscillation circuit) for driving the piezoelectric vibrating piece 3). It has a function to connect to.
As shown in FIG. 3, the wiring board 211 has a pair of connection terminals 211 a and 211 b formed on at least a surface facing the package 2. In addition, the wiring board 211 has a lead electrode (not shown) for pulling out the connection terminals 211 a and 211 b to the outside of the package 2. For example, the connection terminals 211a and 211b are formed by screen-printing and firing a metal wiring material such as tungsten (W) or molybdenum (Mo) on a ceramic insulating material, and nickel (Ni) or gold (Au) or the like thereon. It can be formed by plating.

  As shown in FIGS. 1 and 3, the connection terminal 211a is made of, for example, a metal material and is electrically connected to the bonding pad 322 by a conductive wire 51 having conductivity. Similarly, the connection terminal 211 b is also electrically connected to the bonding pad 332 by the conductive wire 52. The connection between the connection terminal 211a and the bonding pad 322 by the wire 51 and the connection between the connection terminal 211b and the bonding pad 332 by the wire 52 can be easily performed by a wire bonding method.

  Thus, by connecting the connection terminals 211a and 211b and the bonding pads 322 and 332 using the conductive wires 51 and 52, these connection states can be more reliably maintained. Specifically, in the piezoelectric vibrator 1, a conventional conductive adhesive is not used as a means for conducting the connection terminal 211a and the bonding pad 322 (the same applies to the connection between the connection terminal 211b and the bonding pad 332). Thus, it is ensured that the piezoelectric vibrator 1 does not drive or a frequency jump of the piezoelectric vibrating piece 3 due to a temperature change occurs due to a conventional problem, that is, a conduction failure between the connection terminal 211a and the bonding pad 322. Can be prevented. Therefore, the piezoelectric vibrator 1 having excellent reliability and temperature characteristics can be obtained. Moreover, according to such a piezoelectric vibrator 1, it is possible to easily downsize the apparatus while maintaining excellent reliability and temperature characteristics.

Further, by connecting the conductive wires 51 and 52 to the bonding pads 322 and 332, a portion where the thickness shear vibration of the piezoelectric vibrating piece 3 substantially occurs (a portion sandwiched between the electrode portions 321 and 331) is avoided. Since the conductive wires 51 and 52 can be connected, the piezoelectric vibrating piece 3 can be driven smoothly.
The frame member 212 is provided so as to cover the periphery of the piezoelectric vibrating piece 3. The frame member 212 can be formed, for example, by laminating and firing a plurality of frame-shaped ceramic sheets (ceramic green sheets).

  The lid 22 is made of metal, for example. Such a lid 22 is formed on the frame member 212 and is seam welded to the base 21 via a sealing 23 made of, for example, an iron-nickel-cobalt (Fe-Ni-Ko) alloy. Thereby, the piezoelectric vibrating reed 3 in the package 2 is hermetically sealed. Note that the package 2 may be in a vacuum or may be filled with an inert gas such as nitrogen gas or argon gas.

[adhesive]
The adhesive 4 has a function of fixing the piezoelectric vibrating piece 3 to the package 2. The adhesive 4 fixes the piezoelectric vibrating reed 3 to the wiring board 211 so as not to contact the wiring board 211 on the lower surface 312 side.
As shown in FIGS. 1 and 3, the adhesive 4 is bonded to the right end of the lower surface 312 of the piezoelectric substrate 31 in the x-axis direction and to the center in the y-axis, and the piezoelectric vibrating reed 3 is attached to the wiring substrate 211. Cantilevered support. By fixing the piezoelectric vibrating piece 3 at such a position, it is possible to fix the piezoelectric vibrating piece 3 while avoiding a portion where the thickness vibrating vibration substantially occurs in the piezoelectric vibrating piece 3. It can be driven smoothly.

The adhesive 4 is located between the bonding pads 322 and 332 in the plan view of the piezoelectric substrate 31. That is, since the adhesive 4 is not located in the region where the electrode portions 321 and 331 are formed, it is possible to prevent the adhesive 4 from inhibiting the driving of the piezoelectric vibrating reed 3.
The size of the adhesive 4 is not particularly limited, but the length (maximum length) 1 in the y-axis direction is preferably shorter than the length L of the electrode portions 321 and 331 in the y-axis direction. That is, it is preferable to satisfy the relationship of l <L.

  In the piezoelectric vibrating piece 3, when a stress in the y-axis direction (in the crystal axis, the Z′-axis direction) is applied to the piezoelectric substrate 31, the frequency shifts and a desired frequency characteristic cannot be obtained. One cause of such stress is thermal expansion of the piezoelectric substrate 31. Since the linear expansion coefficients of the piezoelectric substrate 31 and the adhesive 4 bonded to the piezoelectric substrate 31 are different from each other, if they are placed at the same temperature, one of them inhibits the expansion of the other. The stress as described above is applied to the substrate 31 (thermal distortion occurs).

Therefore, by satisfying the relationship of l <L, the length of the adhesive 4 in the y-axis direction can be made relatively short. Due to the thermal expansion of the piezoelectric substrate 31, the stress in the y-axis direction is applied to the piezoelectric substrate 31. It can suppress adding. As a result, the frequency shift of the piezoelectric vibrating piece 3 due to the environmental temperature can be suppressed, and the temperature characteristics of the piezoelectric vibrator 1 are improved.
The minimum value of the length 1 of the adhesive 4 in the y-axis direction is not particularly limited as long as it has a strength capable of supporting the piezoelectric vibrating piece 3 with respect to the wiring board 211.

The adhesive 4 is provided so that the entire region is located between both ends of the electrode portions 321 and 331 in the y-axis direction. Thereby, the piezoelectric vibrating piece 3 can be fixed to the wiring board 211 in a more stable state.
As such an adhesive 4, it is preferable to use a non-conductive adhesive that does not substantially pass electricity. Thereby, it is possible to prevent the various wires and terminals of the piezoelectric vibrator 1 from being electrically connected via the adhesive 4 unintentionally. Therefore, the arrangement position of the adhesive 4 and the degree of freedom of the wiring pattern are improved.

  As the non-conductive adhesive, various adhesives such as silicone, polyimide, and epoxy can be used. Among these, silicone adhesive is preferable. Silicone adhesives are relatively soft adhesives. Therefore, by using the silicone-based adhesive 4, the adhesive 4 can easily expand and contract, and the stress generated in the piezoelectric substrate 31 due to thermal expansion can be reduced. As a result, the frequency shift of the piezoelectric vibrating piece 3 due to the environmental temperature can be suppressed.

Second Embodiment
Next, a second embodiment of the piezoelectric vibrator of the present invention will be described.
FIG. 4 is a plan view showing a second embodiment of the piezoelectric vibrator of the present invention, and is a sectional view taken along line BB in FIGS. 5 and 4.
Hereinafter, the piezoelectric vibrator of the second embodiment will be described focusing on differences from the above-described embodiment, and description of similar matters will be omitted.
The piezoelectric vibrator 1A according to the second embodiment of the present invention is the same as the piezoelectric vibrator 1 of the first embodiment described above except that the arrangement of the adhesive 4 is different. 4 and 5, the same reference numerals are given to the same configurations as those in the first embodiment described above.

  As shown in FIGS. 4 and 5, in the piezoelectric vibrator 1 </ b> A of the present embodiment, the adhesive 4 overlaps the bonding pad 322 in a plan view of the piezoelectric substrate 31 (a plan view including the x axis and the y axis). A region 41 and a region 42 overlapping the bonding pad 332 are provided. The conductive wire 51 is bonded to a portion overlapping the region 41 of the bonding pad 322 (immediately above the region 41). Similarly, the conductive wire 52 is bonded to a portion overlapping the region 42 of the bonding pad 332 (immediately above the region 42).

By bonding the conductive wires 51 and 52 to the bonding pads 322 and 332 at such positions, the conductive wires 51 and 52 can be bonded to the bonding pads 322 and 332 more reliably.
Specifically, the wire bonding technique, which is a method of connecting the conductive wires 51 and 52, presses the conductive wire inserted through the capillary against the target site while ultrasonically vibrating the capillary (not shown), Join the conductive wire to the target site. Therefore, if the target part is not supported (fixed) by any member, the force for pressing the conductive wire against the target part becomes weak, and the ultrasonic vibration cannot be efficiently transmitted. The bonding strength of the is reduced.

Therefore, as in the present embodiment, the bonding wire 322 and the conductive wire 51 can be bonded with high bonding strength by connecting the conductive wire 51 at a portion overlapping the region 41 of the bonding pad 322. The same applies to the bonding between the bonding pad 332 and the conductive wire 52.
According to the second embodiment as described above, the same effect as that of the first embodiment can be exhibited.

<Third Embodiment>
Next, a third embodiment of the piezoelectric vibrator of the present invention will be described.
6 is a plan view showing a third embodiment of the piezoelectric vibrator of the present invention, FIG. 7 is a sectional view taken along the line CC in FIG. 6, and FIG. 8 is a diagram for explaining the function of the protruding portion shown in FIG. FIG.
Hereinafter, the piezoelectric vibrator of the third embodiment will be described focusing on differences from the above-described embodiment, and description of similar matters will be omitted.
The piezoelectric vibrator 1B according to the third embodiment of the present invention is the same as the piezoelectric vibrator 1 of the first embodiment described above, except that the wiring board 211 has two projecting portions 211c and 211d. In FIG. 6, FIG. 7, and FIG. 8, the same reference numerals are given to the same configurations as those of the first embodiment described above.

As shown in FIGS. 6 and 7, in the piezoelectric vibrator 1 </ b> B of the present embodiment, the wiring board 211 has two projecting portions 211 c and 211 d that project from the upper surface (the surface facing the inside of the package 2). Yes.
The protrusion 211 c is a protrusion whose top surface is parallel to the lower surface 312 of the piezoelectric substrate 31. Such a protrusion 211 c is provided so as to overlap at least a part of the bonding pad 322 in a plan view of the piezoelectric substrate 31 (a plan view including the x axis and the y axis). Further, the protruding portion 211c is not in contact with the piezoelectric vibrating piece 3 in the natural state. And the conductive wire 51 is joined to the part which overlaps with the protrusion part 211c of the bonding pad 322. FIG.

  Similarly, the protrusion 211 d is a protrusion whose top surface is parallel to the lower surface 312 of the piezoelectric substrate 31. Such a protruding portion 211 d is provided so as to overlap at least a part of the bonding pad 332 in a plan view of the piezoelectric substrate 31. Further, the protruding portion 211d is not in contact with the piezoelectric vibrating piece 3 in the natural state. Then, the conductive wire 52 is bonded to a portion overlapping the protruding portion 211d of the bonding pad 332.

  With such a configuration, the conductive wires 51 and 52 can be more reliably bonded to the bonding pads 322 and 332, and contact between the piezoelectric vibrating reed 3 and the package 2 during driving can be prevented. . Specifically, in the natural state, as shown in FIG. 8A, the piezoelectric substrate 31 supported by the adhesive 4 is separated from the protruding portions 211c and 211d. However, in the second embodiment, as shown in FIG. When the conductive wire 51 is bonded to the bonding pad 322 by using the wire bonding technique described above, the adhesive 4 is deformed as shown in FIG. The piezoelectric substrate 31 is displaced so as to come into contact with the protruding portion 211c.

  When the piezoelectric substrate 31 comes into contact with the projecting portion 211c, further displacement is restricted. Therefore, the projecting portion 211c serves as a sleeper for supporting the portion where the bonding pad 322 of the piezoelectric substrate 31 is formed. For the same reason as in the second embodiment, the conductive wire 51 can be firmly bonded to the bonding pad 322. The protruding portion 211d also exhibits the same effect as the protruding portion 211c.

The distance between the protruding portions 211c and 211d and the lower surface 312 of the piezoelectric substrate 31 is not particularly limited, but is preferably 20 μm or less. Thereby, since the deformation amount of the adhesive 4 accompanying the displacement of the piezoelectric substrate 31 when joining the conductive wires 51 and 52 to the bonding pads 322 and 332 can be reduced, the destruction of the adhesive 4 or the piezoelectric The vibration piece 3 can be prevented from being detached from the adhesive 4.
According to the third embodiment as described above, the same effect as that of the first embodiment can be exhibited.

<Fourth embodiment>
Next, a fourth embodiment of the piezoelectric vibrator of the present invention will be described.
FIG. 9 is a plan view showing a fourth embodiment of the piezoelectric vibrator of the present invention, FIG. 10 is a sectional view taken along the line DD in FIG. 9, and FIG. 11 shows a modification of the piezoelectric vibrator shown in FIG. It is a top view.
Hereinafter, the piezoelectric vibrator of the fourth embodiment will be described focusing on differences from the above-described embodiment, and description of similar matters will be omitted.

The piezoelectric vibrator 1C according to the fourth embodiment of the present invention is the same as the piezoelectric vibrator 1 of the first embodiment described above except that the position of the adhesive 4 and the wiring board 211 have the protruding portions 211e. In FIG. 9, FIG. 10, and FIG. 11, the same reference numerals are given to the same configurations as those of the first embodiment described above.
As shown in FIGS. 9 and 10, in the piezoelectric vibrator 1 </ b> C of the present embodiment, the piezoelectric substrate 1 of 1 is arranged so that the adhesive 4 overlaps at least a part of the bonding pad 322 in a plan view of the piezoelectric substrate 31. It is provided at one corner (corner located at the upper right in FIG. 9). The conductive wire 51 is bonded to a portion of the bonding pad 322 that overlaps the adhesive 4. By setting it as such a structure, the conductive wire 51 can be firmly joined with respect to the bonding pad 322 with a wire bonding technique for the same reason as 2nd Embodiment mentioned above. As a result, the reliability of the piezoelectric vibrator 1 is improved.

  As shown in FIGS. 9 and 10, in the piezoelectric vibrator 1 </ b> C of this embodiment, the wiring board 211 has a protruding portion 211 e that protrudes from the upper surface (the surface facing the inside of the package 2). The protrusion 211 e is a protrusion whose top surface is parallel to the lower surface 312 of the piezoelectric substrate 31. Such a protrusion 211e is provided so as to overlap at least a part of the bonding pad 332 in a plan view of the piezoelectric substrate 31 (a plan view including the x axis and the y axis). Further, the protruding portion 211e is not in contact with the piezoelectric vibrating piece 3 in the natural state.

And the conductive wire 52 is joined to the part which overlaps with the protrusion part 211e of the bonding pad 332. With this configuration, the conductive wire 52 can be firmly bonded to the bonding pad 332 by the wire bonding technique for the same reason as in the third embodiment described above.
In the present embodiment, the mode in which the adhesive 4 is positioned near one corner of the piezoelectric substrate 31 has been described. However, the present invention is not limited to this. For example, as illustrated in FIG. The form located in the center may be used. Further, in the present embodiment, the mode in which the adhesive 4 is provided so as to correspond to the bonding pad 322 and the protruding portion 211e is provided so as to correspond to the bonding pad 332 has been described, but this may be reversed. .
According to the fourth embodiment as described above, the same effect as that of the first embodiment can be exhibited.

Next, the oscillator of the present invention will be described.
FIG. 12 is a plan view showing a preferred embodiment of the oscillator of the present invention, and FIG. 13 is a cross-sectional view taken along line EE in FIG.
As shown in FIGS. 12 and 13, the oscillator 6 includes a package 7, a piezoelectric vibrating piece 3 and an IC chip 8 housed in the package 7, and an adhesive 4 that fixes the piezoelectric vibrating piece 3 to the package 7. is doing. Hereinafter, although each structure of the oscillator 6 is demonstrated, since it is the same as that of the structure described in 1st Embodiment about the piezoelectric vibrating piece 3 and the adhesive agent 4, the description is abbreviate | omitted. In addition, as a structure of the piezoelectric vibrating piece 3 and the adhesive agent 4, the structure in any one of 2nd Embodiment-4th Embodiment mentioned above can also be used.

The package 7 has a box-shaped base 71 and a lid 72 provided so as to close the opening of the base 71. The base 71 is configured by laminating a wiring board (substrate) 711 on which the piezoelectric vibrating piece 3 and the IC chip 8 are fixed, and a frame-shaped frame member 712.
For example, the wiring substrate 711 is configured by forming electrodes, terminals, and the like on an insulating ceramic substrate. The wiring substrate 711 is formed with a recess 711a that opens at the center of the upper surface (the surface facing the package 7). The piezoelectric vibrating reed 3 and the IC chip 8 are fixed to the bottom surface of the recess 711a via the adhesive 4 and the adhesive 9, respectively.

In particular, in the oscillator 6 of the present embodiment, the piezoelectric vibrating reed 3 and the IC chip 8 are disposed without overlapping each other in the thickness direction (Z-axis direction), so that the oscillator 6 can be reduced in size (thinned). Can do.
In addition, the wiring board 711 has four IC connection terminals 101 to 104 on the upper surface thereof and around the recess 711a. These four IC connection terminals 101 to 104 are led out of the package 7 by, for example, an intra-layer wiring (not shown) such as a conductive through hole formed so as to penetrate the wiring board 711.

The frame member 712 is provided so as to surround the periphery of the piezoelectric vibrating piece 3 and the IC chip 8. The frame member 712 can be formed, for example, by firing in a state where a plurality of frame-shaped ceramic sheets (ceramic green sheets) are laminated.
The lid 72 is made of metal, for example. Such a lid 72 is formed on the frame member 712 and is seam welded to the base 71 via a sealing 73 made of, for example, an iron-nickel-cobalt (Fe-Ni-Ko) alloy. Thereby, the piezoelectric vibrating reed 3 and the IC chip 8 in the package 7 are hermetically sealed. Note that the inside of the package 7 may be a vacuum or may be filled with an inert gas such as nitrogen gas or argon gas.

The IC chip 8 of the present embodiment includes a circuit that drives (oscillates) the piezoelectric vibrating reed 3 and a circuit that generates an external output signal of the oscillator 6. The IC chip 8 has six electrode pads 81, 82, 83, 84, 85 and 86 formed so as to be exposed to the outside. Of these, the electrode pads 81 and 82 are drawn from a circuit for driving the piezoelectric vibrating reed 3, and the electrode pads 83, 84, 85, and 86 are drawn from a circuit for generating an external output signal.
The electrode pads 83, 84, 85, 86 are electrically connected to the IC connection terminals 101, 102, 103, 104 via the conductive wires 53, 54, 55, 56.

  The electrode pad 81 is electrically connected directly to the bonding pad 322 of the piezoelectric vibrating piece 3 via the conductive wire 51. Similarly, the electrode pad 82 is directly electrically connected to the bonding pad 332 via the conductive wire 52. In this manner, the bonding pads 322 and 332 and the electrode pads 81 and 82 are directly connected via the conductive wires 51 and 52, whereby the wiring length between the bonding pads 322 and 332 and the electrode pads 81 and 82 is obtained. Since the wiring resistance can be reduced, it is possible to save power for driving the piezoelectric vibrating reed 3.

The oscillator described in the above embodiment can be implemented as the following modifications.
FIG. 14 is a plan view showing another embodiment of the oscillator of the present invention.
The oscillator 6A shown in FIG. 14 is the same as the oscillator 6 described above except that the connection method between the bonding pads 322 and 332 and the electrode pads 81 and 82 is different. In FIG. 14, the same components as those of the oscillator 6 described above are denoted by the same reference numerals.

  In the oscillator 6A shown in FIG. 14, a wiring board 711 has connection wirings 105 and 106 formed on the upper surface thereof. The connection wiring 105 is connected to the bonding pad 322 via the conductive wire 51, and is connected to the electrode pad 81 via the conductive wire 57. Similarly, the connection wiring 106 is connected to the bonding pad 332 through the conductive wire 52, and is connected to the electrode pad 82 through the conductive wire 58.

  With such a configuration, it becomes easy to inspect the vibration characteristics of the piezoelectric vibrating piece 3 during the manufacturing stage of the oscillator 6A. That is, as a method of manufacturing the oscillator 6A, first, the base 71 is prepared, then the piezoelectric vibrating piece 3 is fixed to the easy base 71 via the adhesive 4, and then the bonding pads 322, 332 and connection wirings 105 and 106 are connected. At this stage, the frequency characteristics of the piezoelectric vibrating piece 3 can be easily inspected by connecting a tester to the connection wirings 105 and 106. Then, the IC chip 8 may be mounted and sealed with the lid 72 if the frequency characteristic is within the specified value by the inspection, and the outside of the specified value may be discarded.

As described above, the piezoelectric vibrator and the oscillator of the present invention have been described based on the illustrated embodiments. However, the present invention is not limited to these, and the configuration of each part is an arbitrary configuration having the same function. Can be substituted. Moreover, other arbitrary structures and processes may be added. Moreover, you may combine each embodiment mentioned above suitably.
In the embodiment described above, the piezoelectric vibrating piece has been described as having a piezoelectric substrate having a flat plate shape (both the upper surface and the lower surface are substantially flat surfaces). However, the piezoelectric vibrating piece is not limited to this, for example, a mesa type Or reverse mesa type.

  1, 1A, 1B, 1C ... Piezoelectric vibrator 2 ... Package 21 ... Base 211 ... Wiring board 211a, 211b ... Connection terminal 211c, 211d, 211e ... Projection part 212 ... Frame member 22 ... Lid 23 ... Sealing 3 ... Piezoelectric vibrating piece 31 ... Piezoelectric substrate 311 ... Upper surface (first surface) 312 ... Lower surface (second surface) 32 ... Excitation electrode (first excitation electrode) 321 ... Electrode part (first electrode part) 322 ... Bonding pad (first terminal) 323 ... Wiring 33 ... Excitation electrode (second excitation electrode) 331 ... Electrode part (second electrode part) 332 ... Bonding pad (second terminal) 333 Wiring 4 Adhesive 41, 42 Area 51 to 58 Conductive wire 6, 6A Oscillator 7 Package 71 Base 711 ... Wiring board (board) 711a ... Recess 712 ... Frame member 72 ... Lid 73 ... Sealing 8 ... IC chip 81 to 86 ... Electrode pad 9 ... Adhesive 101 to 104 ... IC connection terminal 105, 106 Connection wiring

Claims (13)

A wiring board;
A piezoelectric vibrating piece;
An adhesive for fixing the piezoelectric vibrating piece to the wiring board;
The piezoelectric vibrating piece includes a piezoelectric substrate that performs thickness shear vibration, and a pair of excitation electrodes provided on the piezoelectric substrate,
Each of the pair of excitation electrodes is electrically connected to the wiring substrate by a conductive wire.   One excitation electrode of the pair of excitation electrodes is formed on the first surface of the first surface, which is one main surface of the piezoelectric substrate, on the first surface, and on the first surface. A first terminal electrically connected to one electrode portion, and the other excitation electrode is disposed on a second surface opposite to the first surface of the piezoelectric substrate via the piezoelectric substrate. A second electrode portion formed so as to face the first electrode portion, and a second terminal formed on the first surface and electrically connected to the second electrode portion. The piezoelectric vibrator according to claim 1, wherein each of the first terminal and the second terminal is electrically connected to the wiring board by the conductive wire. When two axes orthogonal to each other in plan view of the piezoelectric substrate are defined as a first axis and a second axis, the first terminal and the second terminal are one end portions of the first surface in the first axis direction. And spaced apart in the second axial direction,
3. The adhesive fixes the piezoelectric vibrating piece to the wiring board at the first terminal in the first axial direction on the second surface and an end portion on the second terminal side. The piezoelectric vibrator described in 1.   When the length of the adhesive in the second axial direction is l and the length of the first electrode portion and the second electrode portion in the second axial direction is L, l <L The piezoelectric vibrator according to claim 3, wherein the relation is satisfied.   5. The piezoelectric vibrator according to claim 2, wherein the adhesive is located between the first terminal and the second terminal in a plan view of the piezoelectric substrate. The adhesive has a portion overlapping the first terminal and the second terminal in a plan view of the piezoelectric substrate,
The conductive wire that connects the first terminal and the wiring board is connected to the first terminal at a portion overlapping the adhesive of the first terminal,
6. The conductive wire that connects the second terminal and the wiring board is connected to the second terminal at a portion of the second terminal that overlaps the adhesive. The piezoelectric vibrator according to any one of the above.   The wiring board includes, in a plan view of the piezoelectric substrate, a protruding portion that protrudes toward the piezoelectric substrate so as to include a portion to which the conductive wire of the first terminal is connected, and the second terminal. The piezoelectric vibrator according to claim 2, further comprising at least one of projecting portions projecting toward the piezoelectric substrate so as to include a portion to which a conductive wire is connected.   The piezoelectric vibrator according to claim 7, wherein a distance between the protruding portion and the piezoelectric substrate is 20 μm or less. A substrate,
A piezoelectric vibrating piece;
An adhesive for fixing the piezoelectric vibrating piece to the substrate;
A circuit element mounted on the substrate and driving the piezoelectric vibrating piece;
The piezoelectric vibrating piece includes a piezoelectric substrate that performs thickness shear vibration, and a pair of excitation electrodes provided on the piezoelectric substrate,
Each of the pair of excitation electrodes is electrically connected to the circuit element directly or indirectly by a conductive wire.   The oscillator according to claim 9, wherein the circuit element is provided so as not to overlap the piezoelectric vibrating piece in a plan view of the substrate.   The oscillator according to claim 9 or 10, wherein the circuit element and the piezoelectric vibrating piece are accommodated in the same space.   The oscillator according to any one of claims 9 to 11, wherein the pair of excitation electrodes are directly connected to the circuit element by the conductive wire.   The oscillator according to any one of claims 9 to 12, wherein the pair of excitation electrodes are respectively provided on the wiring board and connected to the oscillation circuit via a wiring to which the conductive wire is connected.

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