JP2010010734A - Piezoelectric vibration chip and piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a tuning fork type piezoelectric oscillator (20) for obtaining a scheduled number of oscillation frequencies. <P>SOLUTION: The tuning fork type piezoelectric vibration chip (20) has: a base part (29) having a front surface and a back surface; a pair of vibrating arms (21) extended in a prescribed direction from the base part; and exciting electrodes (23 and 25) on both sides and side surfaces formed to the pair of vibrating arms. At a position of a node of a standing wave of the vibrating arms, a first through-hole (40) going through both sides is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tuning fork type piezoelectric vibrating piece having a through hole in a groove and a technology of a piezoelectric device.

  Conventionally, in consumer and industrial electronic devices such as watches, home appliances, various information / communication devices and OA devices, a crystal resonator, a crystal vibrating piece and an IC chip are sealed in the same package as the clock source of the electronic circuit. Quartz devices such as stopped crystal oscillators and real-time clock modules are widely used.

  In particular, these quartz devices have recently been required to be further reduced in size and thickness as electronic devices on which they are mounted are reduced in size and thickness. Further, there is a demand for a crystal device that secures a low CI (crystal impedance) value and has high quality and excellent stability. In order to keep the CI value low, for example, a tuning-fork type crystal vibrating piece having a vibrating arm structure has been developed, and a vibrating arm formed with a groove portion to improve vibration efficiency is used.

  According to Patent Document 1, as shown in FIG. 9A, this tuning fork type crystal vibrating piece is provided with a vibrating arm 121 at a base portion 129 and a groove portion 127 at each vibrating arm 121. These groove portions 127 have the effect of greatly improving the electric field efficiency and suppressing the CI value low. The lowermost portion between the vibrating arm 121 and the vibrating arm 121 is curved. The groove 127 is formed by slightly biting into the base 129 side from the lowermost AA line of the vibrating arm 121. In addition, a through hole 140 is formed in the groove 127 at substantially the same position as the curved portion 126. The through hole is formed in a square shape, and the size thereof may be the same as the width of the groove 127. However, in FIG. 9A, electrodes are not displayed for easy understanding of the drawing.

  An enlarged view of the excitation electrode portion of the tuning-fork type quartz vibrating piece shown in FIG. 9A is shown in FIG. The excitation electrode includes a first excitation electrode 123 and a second excitation electrode 125, and is also formed in the groove 127 and the through hole 140. FIG. 9C shows a cross-sectional view of the excitation electrode of the groove 127 and the through hole 140 shown in the BB cross section of FIG. 9B.

  By forming the through-hole 140 in this way and forming the excitation electrode, the electric field strength increases as shown in the schematic diagram of the electric field lines indicated by the arrows in FIG. 9C, thereby increasing the vibration efficiency and further increasing the CI value. There is an effect to suppress low.

However, if the size of the through-hole 140 is too large, the vibration mode between the surfaces facing each other in the through-hole 140 becomes large, and a planned vibration frequency, for example, 32.768 kHz cannot be obtained.
JP 2006-217603 A

  Opening a through hole in the groove as described above has a risk of forming an unstable tuning-fork type crystal vibrating piece depending on the position and size. In addition, controlling the size of the through holes in the etching manufacturing process is a difficult task in terms of etching characteristics.

  An object of the present invention is to produce a tuning fork crystal resonator that can obtain a predetermined vibration frequency by appropriately positioning the through hole in a tuning fork crystal resonator having a groove. It is another object of the present invention to manufacture a tuning fork crystal resonator having a low CI value by suppressing a deviation in vibration frequency due to a difference in the size of a through hole in the manufacturing process.

In order to achieve the above object, a piezoelectric vibrating piece according to a first aspect includes a base having a front surface and a back surface, a pair of vibrating arms extending in a predetermined direction from the base, and a table formed on the pair of vibrating arms. A tuning fork-type piezoelectric vibrating piece having back and side excitation electrodes. And the 1st through-hole which penetrates front and back is formed in the position of the node (node) of the standing wave of a vibrating arm.
With this configuration, by making the through hole 40 in the node of the vibrating arm, vibration based on the node can be easily obtained, and a predetermined standing wave can be stably oscillated.

In the tuning fork type piezoelectric vibrating piece according to the second aspect, a groove portion extending in a predetermined direction is formed on the front surface and the back surface of the vibrating arm, and a first through hole is formed in the groove portion.
With this configuration, the vibration efficiency of the vibrating arm can be increased and the CI value can be reduced.

In the tuning fork type piezoelectric vibrating piece according to the third aspect, an excitation electrode is formed in the first through-hole, and this excitation electrode connects the excitation electrode on the front surface and the excitation electrode on the back surface.
With this configuration, the electric field strength is increased and vibration is efficiently performed.

In the tuning fork type piezoelectric vibrating piece of the fourth aspect, in the third aspect, the base electrode is not formed with a connection electrode that connects the excitation electrode on the front and back surfaces of one of the pair of vibrating arms to the other side electrode.
Since the connection electrode had a part with a line width of about 0.01 mm, problems such as disconnection occurred. However, the defect rate can be reduced by eliminating this connection electrode.

In the second aspect, the tuning fork type piezoelectric vibrating piece according to the fifth aspect is formed such that two or more grooves are displaced in the predetermined direction on the front and back surfaces of each of the pair of vibrating arms.
With this configuration, since the groove is divided into two or more, the CI value can be reduced and the rigidity of the vibrating arm can be increased.

The tuning fork-type piezoelectric vibrating piece according to the sixth aspect has a second through hole that connects the excitation electrode on the front surface and the excitation electrode on the back surface in the vicinity of the root where the vibrating arm extends from the base.
With this configuration, the electric field is enhanced to assist vibration near the base of the vibrating arm.

A piezoelectric device according to a seventh aspect includes the tuning fork type piezoelectric vibrating piece according to any one of the first to sixth aspects, and a package that houses the tuning fork type piezoelectric vibrating piece.
Since the tuning fork type piezoelectric device capable of stably oscillating a predetermined standing wave as described above is used, a stable piezoelectric device is obtained.

  According to the present invention, it is possible to manufacture a crystal device with high quality and excellent stability by forming the through holes at appropriate positions. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Configuration of tuning fork type crystal vibrating piece 20>
FIG. 1A is a plan view showing the overall configuration of a tuning-fork type crystal vibrating piece 20 having two vibrating arms 21 and having four groove portions 27 in the vibrating arms 21. For example, the through hole 40 is located in the groove 27a near the center of the vibrating arm 21a. FIG. 1B is a BB cross-sectional view of the vibrating arm 21 a of the tuning fork type crystal vibrating piece 20. The through hole 40 penetrates the groove 27a, and the first excitation electrode 23d is connected to the front and back. Further, the second vibrating electrode 25d is connected to the opposite side of the vibrating arm 21b on the front and back sides.

  The base material of the tuning fork type crystal vibrating piece 20 is formed of a crystal single crystal wafer 10 processed into a Z plate. In order to obtain the required performance in a small size, as shown in FIG. 1A, the tuning fork type crystal vibrating piece 20 is divided into two branches in parallel to the base 29 and from one end of the base 29 toward the Y direction. A pair of vibrating arms 21 extending in the direction is provided. The bases 26 of the pair of vibrating arms 21 are provided with a tapered portion to suppress fluctuations and variations in the resonance frequency due to changes in the ambient temperature. The shape of the tapered portion of the base 26 may be U-shaped or V-shaped. Hereinafter, in the present embodiment, the tuning fork type crystal vibrating piece 20 including a pair of vibrating arms 21 will be described, but the tuning fork type crystal vibrating piece 20 including three or four vibrating arms 21 may be used. Further, the vibrating arms 21 need to have an interval that does not collide with each other due to an overamplitude in the manufacturing process.

  The tuning fork type crystal vibrating piece 20 is a vibrating piece that transmits a signal at, for example, 32.768 kHz, and is an extremely small vibrating piece. The overall length is about 1.7 mm and the width is about 0.5 mm. Grooves 27 are formed on both front and back surfaces of the vibrating arm 21 of the tuning fork type crystal vibrating piece 20. Two groove portions 27 are formed on the surface of one vibrating arm 21, and two groove portions 27 are similarly formed on the back surface side of the vibrating arm 21. That is, eight groove portions 27 are formed on the pair of vibrating arms 21 on the front and back sides. The rigidity (strength) of the vibrating arm 21 can be increased by dividing the groove 27 into a plurality. The depth of the groove portion 27 is about 35 to 45% of the thickness of the quartz single crystal wafer 10, and the groove portion 27 is present on both the front and back surfaces. Therefore, as shown in FIG. It is formed in an H shape. The groove part 27 is provided in order to suppress an increase in the CI value. In this embodiment, for example, the thickness of the crystal single crystal wafer 10 is 120 μm, and the depth of the groove 27 is about 100 μm on the front and back sides.

  The base 29 of the tuning fork type crystal vibrating piece 20 is formed in a substantially plate shape as a whole. The length of the base 29 with respect to the vibrating arm 21 is about 36%. Two connecting portions 28 are provided at one end of the base portion 29 of the tuning-fork type crystal vibrating piece 20 and at the base of the pair of vibrating arms 21. The connecting portion 28 is a portion for connecting the crystal single crystal wafer 10 and the tuning fork type crystal vibrating piece 20 when the tuning fork shape shown in FIG. 1 is formed from the crystal single crystal wafer 10 by photolithography and wet etching.

  A first electrode pattern 23 and a second electrode pattern 25 are formed on the vibrating arm 21 and the base 29 of the tuning fork type crystal vibrating piece 20. Both the first electrode pattern 23 and the second electrode pattern 25 have a structure in which a gold (Au) layer of 100 angstroms to 1000 angstroms is formed on a chromium (Cr) layer of 50 angstroms to 1000 angstroms. That is, when the first layer and the second layer are combined, the thickness of the electrode pattern is 150 Å to 20000 Å. Further, a tungsten (W) layer, a nickel (Ni) layer, a nickel tungsten layer, or a titanium (Ti) layer may be used instead of the chromium (Cr) layer, and silver instead of the gold (Au) layer. An (Ag) layer may be used. In some cases, an aluminum (Al) layer, a copper (Cu) layer, or a silicon (Si) layer is used.

  As shown in FIG. 1A, a first base electrode 23a and a second base electrode 25a are formed on the base 29 of the tuning-fork type crystal vibrating piece 20, and a first excitation is formed in the groove 27 of the arm 21a. The second excitation electrode 25d is formed in the groove portion 27 of the electrode 23d and the arm portion 21b. In addition, as shown in FIG. 1B, second excitation (side) electrodes 25c are formed on both side surfaces of the arm portion 21a. Further, first excitation (side) electrodes 23c are formed on both side surfaces of the arm portion 21b.

<Configuration of single crystal quartz wafer>
FIG. 2 is a plan view showing a crystal single crystal wafer on which an outer shape of a tuning fork type crystal vibrating piece is formed.

  FIG. 2A shows a circular quartz single crystal wafer 10. The circular quartz single crystal wafer 10 is made of, for example, an artificial quartz having a thickness of 120 μm, and the diameter of the circular quartz single crystal wafer 10 is 3 inches or 4 inches. Furthermore, an orientation flat 10c for specifying the crystal direction of the crystal is formed on a part of the peripheral portion of the crystal single crystal wafer 10 so that the axial direction of the circular crystal single crystal wafer 10 can be specified.

  FIG. 2B shows a rectangular crystal single crystal wafer 15. The rectangular quartz single crystal wafer 15 is also made of, for example, an artificial quartz having a thickness of 120 μm, and one side of the rectangular quartz single crystal wafer 15 is 2 inches. An orientation flat 15c for specifying the crystal direction of the crystal is formed on a part of the peripheral portion of the rectangular crystal single crystal wafer 15 so that the axial direction of the rectangular crystal single crystal wafer 15 can be specified.

  The circular crystal single crystal wafer 10 in FIG. 2A and the rectangular crystal single crystal wafer 15 in FIG. 2B are provided with a plurality of window portions 18 in relation to process control and wafer strength. A plurality of tuning fork type crystal vibrating pieces 20 are formed in the part. In each window portion 18, a connection portion 28 is formed to connect the crystal wafer 10 and the tuning fork type crystal vibrating piece 20.

Embodiment 1
The tuning fork type crystal vibrating piece 20 oscillates a standing wave of 32.768 kHz, for example. The standing wave oscillates as a double wave standing wave as shown in FIG. This standing wave has a stationary point called a node. There are two nodes, and the position does not change as long as the vibration is doubled.

  FIG. 3B is a diagram illustrating a state in which the conceptual tuning fork vibrates with a standing wave. By applying force or vibration, the tuning fork oscillates a standing wave of double vibration. A tuning fork made of metal or the like also has a node and has two nodes in double vibration.

  Similarly, the tuning fork type crystal vibrating piece 20 has the vibrating arm 21 fixed to the base 29, but in the same manner as the conceptual tuning fork, by receiving an electric field from the excitation electrode, it oscillates a double-wave standing wave and produces two nodes. (Node). FIG. 3C shows the position of the node and the state of double vibration. However, in the tuning-fork type crystal vibrating piece 20 illustrated in FIG. 3C, two nodes move toward the base 29 side from the two nodes illustrated in FIG. 3B. ing. This is because the vibrating arm 21 is more firmly fixed to the base 29 than a tuning fork made of metal or the like.

  FIG.3 (d) has shown the AA cross section of Fig.1 (a). FIG. 3D is a cross-sectional view when the through hole 40 is formed at the position of the node. In FIG. 3D, a through hole 40 is opened between the groove 27a and the groove 27c, which are the first groove 27 from the base 29. Of course, the position of the through hole 40 can be changed depending on the position of the node of the tuning fork type crystal vibrating piece 20. Further, the position of the through hole 40 may be provided between the groove portion 27b and the groove portion 27d which are the second place from the base portion.

  The position of the node is a standing wave of that frequency, and the position is different. For example, a basic vibration whose both ends are free (free end) has one node as shown in FIG. The double vibration has two nodes as shown in FIG. The triple vibration has three nodes as shown in FIG. The quadruple vibration has four nodes as shown in FIG. As described above, the node position is determined so as to divide the length of the vibration member according to the frequency thereof, and thus the position is different.

  For this reason, opening the through hole 40 that increases the electric field strength at the node of the tuning fork type crystal vibrating piece 20 makes it easier to obtain vibration based on the node, and the vibration of 32.768 kHz, which is double vibration. The standing wave can be oscillated stably, and the vibration efficiency is increased and the CI value is reduced. And other 3 times vibration, 4 times vibration, etc. become difficult to generate. The through hole 40 may have a square shape or a round shape.

  As described above, the through-hole 40 can be formed at an appropriate position of the tuning fork type crystal vibrating piece 20, thereby forming the tuning fork type crystal vibrating piece 20 with higher accuracy and stability.

  In addition, opening the through hole 40 can simplify the wiring diagram of the excitation electrode, and has an effect of preventing disconnection in the manufacturing process.

  As shown in FIG. 1B, the tuning-fork type crystal vibrating piece 20 is formed with an excitation electrode in the through hole 40 so that the first excitation electrode 23d of the groove 27b of the vibrating arm 21a is connected on the front and back. As a result, the groove 27a, the groove 27b, the groove 27c, and the groove 27d shown in FIG. Similarly, the groove 27a and the groove 27b of the vibrating arm 21b are connected to the groove 27c and the groove 27d by the second excitation electrode 25d so as to have the same potential.

  The conduction of the excitation electrode of the groove 27 on the front and back surfaces in this way eliminates the need for the connection electrode 123a having a thin surface as shown in FIG. The connection electrode 123a is an electrode for connecting the first excitation electrode 23d on the surface and the first excitation (side) electrode 23c. Similarly, a connection electrode 125a (not shown) for connecting the second excitation electrode 25d and the second excitation (side surface) electrode 25c is formed on the back surface, and this connection electrode 125a is also unnecessary. Since the connection electrode 123a or 125a has to be formed with a portion having a line width of about 0.01 mm, a problem such as disconnection has occurred. However, these are unnecessary, and there is no concern about disconnection, and the defect rate is reduced.

  That is, the wiring pattern as shown in FIG. 1A can be simplified, and similarly the back surface can be simplified. In addition, since the wiring pattern of this embodiment can widely use the base 29, measures such as making the other wirings of the base thick and difficult to break, and avoiding damage caused by electrostatic discharge reaction are taken. Make it easier to take. However, the excitation electrode 123a may be formed as an alternative circuit when the excitation electrode in the through hole 40 is disconnected.

<< Embodiment 2 >>
In the first embodiment, one through portion 40 is formed in each vibrating arm 21, but a through hole is provided near the root 26 of the pair of vibrating arms 21, and four through holes are formed in the tuning fork type crystal vibrating piece 20. Thus, the vibration efficiency can be increased and the CI value can be reduced.

  For example, in the metal tuning fork shown in FIG. 3B, the joint 41 between the metal plate bent into a U-shape and the rod supporting it is joined at a point or a small area so as not to inhibit the double vibration. It has become. However, since the vibration rod 21 of the tuning fork type crystal vibrating piece 20 is projected from the surface of the base portion 29, the base portion 29 suppresses the vibration and absorbs the vibration, thereby reducing the vibration efficiency and causing the leakage of the vibration. It was one of the

  For this reason, in the second embodiment, as shown in FIG. 5A, two through holes 40b with excitation electrodes are provided near the roots 26 of the pair of vibrating arms 21, thereby enhancing the electric field and assisting vibration near the base. To do. Thereby, the through-hole 40b can raise vibration efficiency.

  Further, as shown in FIG. 5B, the tuning fork type crystal vibrating piece 20 may be formed in such a manner that the groove 27 is shifted to the base side from the lowermost line 26L of the root 26 and the groove 27 bites into the base 29 side. . Further, by forming the through hole 40b of the tuning fork type crystal vibrating piece 20 slightly below the lowermost line 26L, the vibration efficiency can be increased as described above.

  However, since the purpose of the through hole 40b is to assist vibration, if the size of the through hole 40b is too large, the electric field strength will increase too much and serve as a node. Thereby, the through hole 40b inhibits the double vibration. Thus, since the position and size of the through hole 40b near the root 26 are important, sufficient care must be taken when forming the through hole 40b.

<Manufacturing process of tuning-fork type crystal vibrating device>
FIG. 6 is a flowchart of the manufacturing process for forming the outer shape, the groove 27 and the through hole of the tuning fork type crystal vibrating piece 20. The right view of FIG. 6 shows a part of the single crystal quartz wafer 10 with respect to the CC cross section of FIG. However, the following manufacturing process shows an example of the manufacturing method, and is not limited to this.

  In step S111 of FIG. 6, a metal film 32 is formed by sputtering on the single crystal quartz wafer 10 that has been polished and cleaned as shown in FIG. 6A. The metal film 32 is, for example, a film in which gold (Au) is laminated on a chromium (Cr) base film. In step S112, a photoresist is applied uniformly on the metal film 32 by, for example, a spray method to form a resist film 36 (FIG. 6B).

  In step S113, exposure is performed using a photomask having the outer shape of the tuning-fork type crystal vibrating piece 20 and the through portion 40, and the exposed photoresist 42 is developed and removed. (FIG. 6C).

In step S114, the portion of the metal film 32 not covered with the resist film 36 is removed by etching, and then all the resist film 36 remaining on the single crystal quartz wafer 10 is removed (FIG. 6D).

  In step S115, a photoresist is applied uniformly over the quartz wafer 10 and the metal film 32 again by, for example, a spray method to form a resist film 36 (FIG. 6E).

  In step S116, exposure is performed using a photomask having the groove 27, and the exposed photoresist 42 is developed and removed. (FIG. 6 (f)).

In step S117, a portion where the metal film 32 is etched and the single crystal quartz wafer 10 appears is wet-etched using hydrofluoric acid which is a quartz etching solution, thereby penetrating the outer shape and the through hole 40 (FIG. 6 ( g).
In step S118, the portion of the metal film 32 not covered with the resist film 36 is removed by etching (FIG. 6H).

The single crystal quartz wafer 10 that appears in step S119 is wet-etched using hydrofluoric acid. In this wet etching, the groove 27 is formed by a so-called half-etching operation (FIG. 6 (i)).
In step S120, the remaining resist film 36 and metal film 32 are removed. Then, the groove 27 having the through portion 40 is formed (FIG. 6 (j)).

<Electrode formation and frequency adjustment and packaging process>
The tuning-fork type crystal vibrating piece 20 created in the above manufacturing process is then formed with electrodes, frequency-adjusted and packaged. FIG. 7 shows a flowchart of the process.

  In step S141, the tuning fork crystal vibrating piece 20 is washed with pure water, and a metal film 32 for forming an excitation electrode as a drive electrode is formed on the entire surface of the tuning fork crystal vibrating piece 20 by a technique such as vapor deposition or sputtering. To do.

  In step S142, a photoresist is applied to the entire surface using a spray. Since the tuning fork type crystal vibrating piece 20 is formed with the groove 27 and the like, the photoresist is uniformly applied also to the groove 27.

  In step S143, a photomask corresponding to the first electrode pattern 23 and the second electrode pattern 25 is prepared, and the electrode pattern is exposed to the quartz single crystal wafer 10 coated with the photoresist layer. Since the first electrode pattern 23 and the second electrode pattern 25 need to be formed on both surfaces of the tuning fork type crystal vibrating piece 20, both surfaces of the tuning fork type crystal vibrating piece 20 are exposed.

In step S144, after the photoresist layer is developed, the exposed photoresist layer is removed. The remaining photoresist becomes a photoresist layer corresponding to the first electrode pattern 23 and the second electrode pattern 25. Further, the metal film 32 to be an electrode is etched. That is, the gold layer exposed from the photoresist layer corresponding to the electrode pattern is etched with, for example, an aqueous solution of iodine and potassium iodide, and then the chromium layer is etched with, for example, an aqueous solution of ceric ammonium nitrate and acetic acid.
Subsequently, in step S145, the remaining photoresist is removed. Through these steps, an excitation electrode and the like are formed on the tuning fork type crystal vibrating piece 20 with an accurate position and electrode width.

Through the steps so far, the tuning-fork type crystal vibrating piece 20 in which the first electrode pattern 23, the second electrode pattern 25, the groove 27, and the through hole 40 are formed is obtained.
Therefore, in step S146, the tuning fork type crystal vibrating piece 20 is bonded to the ceramic package 51 shown in FIG. Specifically, the base 29 of the tuning fork type crystal vibrating piece 20 is placed on the conductive adhesive 31 applied to the wiring layer 81, and the conductive adhesive 31 is temporarily cured. Next, the tuning fork type crystal vibrating piece 20 is bonded to the terminal electrode 82 by main curing the conductive adhesive 31 in a curing furnace.

In step S147, the tip of the vibrating arm 21 of the tuning-fork type crystal vibrating piece 20 is further irradiated with laser light to evaporate and sublimate part of the weight metal layer of the vibrating arm 21, thereby performing frequency adjustment by a mass reduction method. .
Next, in step S148, the package 51 containing the tuning-fork type crystal vibrating piece 20 shown in FIG. 8B is transferred into a vacuum chamber or the like, and the lid 71 is joined by the sealing material 57.
Subsequently, in step S149, finally, the driving characteristics of the quartz crystal vibrating device 50 are inspected to complete the quartz crystal vibrating device 50.

<Configuration of crystal vibrating device 50>
The crystal vibrating device 50 will be described with reference to the drawings. FIG. 8 shows a schematic diagram of a crystal resonator device 50 according to an embodiment of the present invention. 8A is an overall perspective view, FIG. 8B is a cross-sectional view, and FIG. 8C is a top view with the metal lid 71 removed.

  The surface mount type crystal vibrating device 50 includes an insulating ceramic package 51 and a metal lid 71 that covers the package of the crystal vibrating device 50. The metal lid 71 is made of Kovar (iron (Fe) / nickel (Ni) / cobalt (Co) alloy). The ceramic package 51 includes a bottom ceramic layer 51a, a wall ceramic layer 51b, and a pedestal bottom ceramic layer 51c, which are pressed from a green sheet using a slurry containing ceramic powder mainly composed of alumina, a binder, and the like. . As a material of the ceramic package 51 constituting the package, glass ceramic may be used instead of ceramic powder mainly composed of alumina, or a non-shrinkable glass ceramic substrate may be used. As understood from FIG. 8B, the package constituted by the plurality of ceramic layers 51 a to 51 c forms a cavity 58, and the tuning fork type crystal vibrating piece 20 is mounted in the cavity 58.

  The wiring pattern of the base portion 29 has an adhesive region that is electrically connected to the conductive adhesive 31. The tuning fork type crystal vibrating piece 20 is bonded with the conductive adhesive 31 so as to be horizontal with the bottom ceramic layer 51a, and generates a predetermined vibration. On a part of the upper surface of the pedestal ceramic layer 51c, a wiring layer 81 is formed which is electrically connected to the bonding region of the tuning-fork type crystal vibrating piece 20. At least two terminal electrodes 82 formed on the lower surface of the ceramic package 51 are external terminals when surface-mounted on a printed board (not shown). The internal wiring 83 is an electrical conduction portion that connects the wiring layer 81 and the terminal electrode 82. A metallized layer is provided at the upper end of the wall ceramic layer 51 b, and a sealing material 57 made of a low-temperature metal brazing material formed on the metallized layer is formed for joining the metal lid 71. The wall ceramic layer 51 b and the metal lid 71 are welded via a sealing material 57.

  In the present embodiment, the case where two groove portions 27 are formed on the front and back surfaces of one vibrating arm 21 has been described. However, one or three or more portions are formed on the front and back surfaces of one vibrating arm 21. A similar tuning fork type crystal vibrating piece 20 having a groove has the same effect.

  The preferred embodiments of the present invention have been described in detail above. However, as will be apparent to those skilled in the art, the present invention can be carried out with various modifications and changes made to the above embodiments within the technical scope thereof. . For example, in the tuning fork type piezoelectric vibrating piece of the present invention, various piezoelectric single crystal materials such as lithium niobate can be used in addition to quartz.

(A) is a top view of a tuning fork type crystal vibrating piece. (B) is a BB cross-sectional view of the crystal resonator depicted in (a). (A) is a circular quartz single crystal wafer. (B) is a rectangular quartz single crystal wafer. (A) is a figure which shows the 2nd vibration of a metal plate. (B) is a figure which shows the 2nd vibration of a metal tuning fork. FIG. 6C is a diagram showing the double vibration of the tuning fork type crystal vibrating piece 20. (D) is AA sectional drawing of the tuning fork type crystal vibrating piece 20 of Fig.1 (a). (A) is a figure which shows the fundamental vibration of a metal plate. (B) is a figure which shows the 2 times vibration of a metal plate. (C) is a figure which shows the 3 times vibration of a metal plate. (D) is a figure which shows the 4 times vibration of a metal plate. FIG. 6 is a view in which a through-hole is provided near the base of a vibrating arm 21 in the tuning-fork type crystal vibrating piece 20 of the second embodiment. 5 is a flowchart of a process for manufacturing the outer shape of the tuning-fork type crystal vibrating piece 20, the groove 27, and the through hole 40. 5 is a flowchart of electrode formation, frequency adjustment, and packaging. (A) is the whole perspective view of the crystal oscillator 50 concerning embodiment, (b) is sectional drawing, (c) is the top view which removed the metal cover body 71. FIG. (A) is a conventional tuning-fork type crystal vibrating piece. (B) is an enlarged view of an excitation electrode portion. (C) is BB sectional drawing of the crystal oscillator drawn to (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Circular single crystal quartz wafer 15 ... Rectangular quartz single crystal wafer 18 ... Window part 20 ... Tuning fork type crystal vibrating piece 21 ... Vibration arm 23 ... First electrode pattern 25 ... Second electrode pattern 26 ... Root (taper part)
27 ... Groove 28 ... Connecting portion 29 ... Base 31 ... Conductive adhesive 32 ... Metal film 36 ... Photoresist layers 40, 40b ... Through hole 42 ... Exposed photoresist 50 ... Quartz vibrating device 51 ... Ceramic package 57 ... Sealing Stop material 58 ... Cavity 71 ... Cover 81 ... Wiring layer 82 ... Terminal electrode 83 ... Internal wiring

Claims (7)

A tuning fork-type piezoelectric vibrating piece having a base having a front surface and a back surface, a pair of vibrating arms extending in a predetermined direction from the base, and excitation electrodes on the front and back surfaces and side surfaces formed on the pair of vibrating arms,
A tuning-fork type piezoelectric vibrating piece, wherein a first through hole penetrating the front and back surfaces is formed at a position of a standing wave node of the vibrating arm.   The tuning fork type piezoelectric vibrating piece according to claim 1, wherein a groove portion extending in a predetermined direction is formed on a front surface and a back surface of the vibrating arm, and the first through hole is formed in the groove portion.   3. The tuning fork type piezoelectric device according to claim 1, wherein an excitation electrode is formed in the first through-hole, and the excitation electrode connects the excitation electrode on the front surface and the excitation electrode on the back surface. 4. Vibrating piece.   4. The quartz crystal vibrating piece according to claim 3, wherein a connection electrode that connects the excitation electrode on one of the front and back surfaces of the pair of vibrating arms to the other side electrode is not formed on the base. 5.   3. The tuning fork type piezoelectric vibrating piece according to claim 2, wherein the groove portion is formed to be shifted in a predetermined direction by two or more on the front and back surfaces of each of the pair of vibrating arms.   6. The second through hole for conducting electrical connection between the excitation electrode on the front surface and the excitation electrode on the back surface is provided in the vicinity of the root where the vibrating arm extends from the base portion. Tuning fork type piezoelectric vibrating piece. The tuning fork type piezoelectric vibrating piece according to any one of claims 1 to 6,
A package for housing the tuning-fork type piezoelectric vibrating piece;
A piezoelectric device comprising: