JP2018082400A - Piezoelectric vibration piece and piezoelectric vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibration piece capable of restraining occurrence of vibration leakage and decrease in impact resistance.SOLUTION: A piezoelectric vibration piece 3 includes a pair of vibration arms 31, 32, and a proximal part 35 for connecting the proximal ends of the pair of vibration arms 31, 32. In the cross-sectional view in parallel with the longitudinal direction of the vibration arms 31, 32, and orthogonal to the width direction of the pair of vibration arms 31, 32, a projection 45 projecting to the distal end side of vibration arms 31, 32 is formed at the fork portion 40 of the pair of vibration arms 31, 32, a step 46 is formed at a part on the opposite side to the projection 45 in the cross-sectional view, and in the cross-sectional view, the step 46 includes a first ramp inclining for one face of the proximal part 35 so that the inner side of the proximal part 35 in the thickness direction is located closer to the projection 45 side, a second ramp inclining for the other face of the proximal part 35 so that the inner side of the proximal part 35 in the thickness direction is located on the opposite side to the projection 45, and a coupling part for coupling the first and second ramps.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a piezoelectric vibrating piece and a piezoelectric vibrator.

Conventionally, a pair of vibrating arm portions, a base portion that connects the base ends of the vibrating arm portions of the pair of arm portions, and a base portion that is coupled to the base portion and disposed outwardly in the width direction of the pair of vibrating arm portions. A so-called side arm type vibration piece including a pair of support arm portions is known (see, for example, Patent Documents 1 and 2).
In recent years, with the miniaturization of electronic devices, demands for miniaturization of piezoelectric vibrators and piezoelectric vibrating pieces are increasing. For example, as a method for obtaining a small piezoelectric vibrating piece, a method is known in which a mask having a shape corresponding to the outer shape of the piezoelectric vibrating piece is formed on both surfaces of a wafer made of a piezoelectric material such as quartz, and the wafer is wet-etched. ing.

JP 2004-357178 A JP 2005-102138 A

  However, when a wafer made of a piezoelectric material such as quartz is subjected to wet etching, a deformed shape made of a natural crystal surface of the piezoelectric material is left as an etching residue on the fork of the pair of vibrating arms or the fork of the support arm and the base. A part may be formed. In this case, since the cross-sectional shape of the fork portion becomes an unbalanced shape in the thickness direction of the piezoelectric vibrating piece, vibration leakage may occur or impact resistance may be reduced.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a piezoelectric vibrating piece and a piezoelectric vibrator that can suppress the occurrence of vibration leakage and the reduction in impact resistance. .

  A piezoelectric vibrating piece according to an aspect of the present invention is a piezoelectric vibrating piece including a pair of vibrating arm portions and a base portion that connects base ends of the pair of vibrating arm portions. In a cross-sectional view that is parallel to the longitudinal direction and perpendicular to the width direction of the pair of vibrating arm portions, a fork portion that protrudes toward the distal end side of the vibrating arm portion is formed on the fork portion of the pair of vibrating arm portions, In a cross-sectional view, a step portion is formed on a portion opposite to the projecting portion, and in the cross-sectional view, the step portion is positioned closer to the projecting portion toward the inner side in the thickness direction of the base portion. A first inclined portion that is inclined with respect to one surface of the base portion, a second inclined portion that is inclined with respect to the other surface of the base portion so as to be located on the opposite side of the protruding portion toward the inner side in the thickness direction of the base portion, And a connecting portion that connects the first inclined portion and the second inclined portion.

According to this configuration, the cross-sectional shape of the fork portion of the pair of vibrating arm portions is formed in the thickness direction of the piezoelectric vibrating piece by forming the step portion on the opposite side to the protruding portion in the cross-sectional view. A well-balanced shape can be obtained. Therefore, occurrence of vibration leakage and reduction in impact resistance can be suppressed.
By the way, when a wafer made of a piezoelectric material such as quartz is subjected to wet etching, a deformed portion made of a natural crystal plane of the piezoelectric material may be formed as a portion remaining on the side opposite to the protruding portion in the sectional view. . The surface of the deformed portion is a surface inclined with respect to the main surface of the wafer. Therefore, according to this configuration, since the first inclined portion and the second inclined portion (that is, the inclined portion of the step portion) can be formed by using the property (etching anisotropy) of the piezoelectric material, the manufacturing efficiency is improved. It is suitable for improvement.

  In the piezoelectric vibrating piece, in the cross-sectional view, an intersection point between the first inclined portion and the connecting portion is a first inflection point, and an intersection point between the second inclined portion and the connecting portion is a second inflection point. Then, the first inflection point and the second inflection point may overlap the protrusion in the thickness direction of the base portion.

  According to this configuration, in the cross-sectional view, the cross section of the fork portion of the pair of vibrating arm portions as compared with the case where the first inflection point and the second inflection point are shifted from the protruding portion in the thickness direction of the base portion. The shape can be further balanced in the thickness direction of the piezoelectric vibrating piece. Therefore, the occurrence of vibration leakage and the reduction in impact resistance can be more reliably suppressed.

  In the above-described piezoelectric vibrating piece, the piezoelectric vibrating piece further includes a pair of support arm portions that are coupled to the base portion and disposed outward in the width direction of the pair of vibration arm portions, and the support arm portion and the base portion in the cross-sectional view. Is formed with a second projecting portion projecting toward the distal end side of the vibrating arm portion, and a second step portion is formed on the opposite side of the second projecting portion in the cross-sectional view. It may be formed.

  According to this configuration, in the cross-sectional view, the second step portion is formed on the portion opposite to the second projecting portion, so that the cross-sectional shape of the second fork portion can be changed in the thickness direction of the piezoelectric vibrating piece. A well-balanced shape can be obtained. Therefore, in the side arm type piezoelectric vibrating piece, it is possible to suppress the occurrence of vibration leakage and the reduction in impact resistance. In particular, since the side arm type piezoelectric vibrating piece has more fork portions than the vibrating piece not provided with the supporting arm portion, it is suitable for suppressing the occurrence of vibration leakage and the reduction in impact resistance.

  A piezoelectric vibrating piece according to an aspect of the present invention includes a pair of vibrating arm portions, a base portion that connects base ends of the pair of vibrating arm portions, and a width direction of the pair of vibrating arm portions that are coupled to the base portion. A pair of support arm portions arranged on the outer side of the piezoelectric vibration piece, in a cross-sectional view parallel to the longitudinal direction of the vibration arm portion and perpendicular to the width direction of the pair of vibration arm portions, At least one of the first fork part of the pair of vibrating arm parts and the second fork part of the support arm part and the base part is formed with a protruding part that protrudes toward the distal end side of the vibrating arm part, In a cross-sectional view, a step portion is formed on a portion opposite to the projecting portion, and in the cross-sectional view, the step portion is positioned closer to the projecting portion toward the inner side in the thickness direction of the base portion. The first inclined portion that is inclined with respect to one surface of the base portion, and the inner side in the thickness direction of the base portion is located on the opposite side to the protruding portion. A second inclined portion inclined with respect to the other surface of said base to so that, characterized in that it comprises a connecting portion connecting the second inclined portion and the first inclined portion.

According to this configuration, in the cross-sectional view, the step portion is formed on the portion opposite to the protruding portion, so that the cross-sectional shape of at least one of the first fork portion and the second fork portion is changed to the piezoelectric vibrating piece. It can be set as a well-balanced shape in the thickness direction. Therefore, in the side arm type piezoelectric vibrating piece, it is possible to suppress the occurrence of vibration leakage and the reduction in impact resistance.
By the way, when a wafer made of a piezoelectric material such as quartz is subjected to wet etching, a deformed portion made of a natural crystal plane of the piezoelectric material may be formed as a portion remaining on the side opposite to the protruding portion in the sectional view. . The surface of the deformed portion is a surface inclined with respect to the main surface of the wafer. Therefore, according to this configuration, since the first inclined portion and the second inclined portion (that is, the inclined portion of the step portion) can be formed by using the property (etching anisotropy) of the piezoelectric material, the manufacturing efficiency is improved. It is suitable for improvement.

  A piezoelectric vibrator according to an aspect of the present invention includes the above-described piezoelectric vibrating piece and a package that accommodates the piezoelectric vibrating piece.

  According to this configuration, in the piezoelectric vibrator including the above-described piezoelectric vibrating piece, it is possible to suppress the occurrence of vibration leakage and the reduction in impact resistance.

  According to the present invention, it is possible to provide a piezoelectric vibrating piece and a piezoelectric vibrator capable of suppressing the occurrence of vibration leakage and the reduction in impact resistance.

1 is an external perspective view of a piezoelectric vibrator according to an embodiment. It is an internal block diagram of the piezoelectric vibrator which concerns on embodiment. It is III-III sectional drawing of FIG. 1 is an exploded perspective view of a piezoelectric vibrator according to an embodiment. It is a top view of the piezoelectric vibrating piece according to the embodiment. It is VI-VI sectional drawing of FIG. It is explanatory drawing of 1 process of the manufacturing method of the piezoelectric vibrating piece which concerns on embodiment. It is a top view of the piezoelectric vibrating piece which concerns on the 1st modification of embodiment. It is a top view of the piezoelectric vibrating piece which concerns on the 2nd modification of embodiment. It is a top view of the piezoelectric vibrating piece which concerns on the 3rd modification of embodiment. It is a top view of the piezoelectric vibrating piece which concerns on the 4th modification of embodiment. It is a top view of the piezoelectric vibrating piece which concerns on the 5th modification of embodiment.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following embodiments, a ceramic package type surface-mount type vibrator will be described as an example of a piezoelectric vibrator. In the drawings used for the following description, the scale of each member is appropriately changed in order to make each member a recognizable size.

  In the following description, an XYZ coordinate system is set, and the positional relationship of each member will be described with reference to this XYZ coordinate system. At this time, the direction perpendicular to the main surface of the piezoelectric vibrating piece (that is, the thickness direction of the piezoelectric vibrating piece) is “Z-axis direction”, and the longitudinal direction of the vibrating arm portion (ie, the longitudinal direction of the piezoelectric vibrating piece) is “Y-axis”. The direction ”, the direction perpendicular to the Y-axis direction and the Z-axis direction (that is, the width direction of the piezoelectric vibrating piece) is defined as“ X-axis direction ”.

[Piezoelectric vibrator]
As shown in FIG. 1, a piezoelectric vibrator 1 includes a package 2 having a cavity C (see FIG. 2) hermetically sealed inside, and a piezoelectric vibrating piece 3 (see FIG. 2) housed in the cavity C. It is equipped with.

  As shown in FIG. 2, the piezoelectric vibrator 1 has a rectangular shape in plan view. In the present embodiment, the longitudinal direction, the width direction, and the thickness direction of the piezoelectric vibrator 1 are the same as the longitudinal direction (Y-axis direction), the width direction (X-axis direction), and the thickness direction (Z-axis direction) of the piezoelectric vibrating piece 3. I'm doing it.

[package]
As shown in FIG. 3, the package 2 includes a package body 5 and a sealing plate 6 that is bonded to the package body 5 and forms a cavity C between the package body 5 and the package body 5.
The package body 5 includes a plate-shaped first base substrate 10, a frame-shaped second base substrate 11 bonded to the first base substrate 10, and a frame-shaped third base substrate bonded to the second base substrate 11. 12 and a frame-like seal ring 13 joined to the third base substrate 12.

  As shown in FIG. 4, at the four corners of the first base substrate 10, the second base substrate 11, and the third base substrate 12, ¼ arc-shaped notches 15 are formed in plan view. The notch 15 is formed over the entire thickness direction of the first base substrate 10, the second base substrate 11, and the third base substrate 12. For example, the first base substrate 10, the second base substrate 11, and the third base substrate 12 are formed by joining a plurality of wafer-shaped ceramic substrates and bonding them, and then forming a plurality of through holes penetrating each ceramic substrate in a matrix. Thereafter, each ceramic substrate is cut into a lattice shape with each through hole as a reference. The notch 15 is formed by dividing the through hole into four.

  Examples of the material for forming the ceramic substrate include HTCC (High Temperature Co-Fired Ceramic) made of alumina, and LTCC (Low Temperature Co-Fired Ceramic) made of glass ceramic.

  As shown in FIG. 3, the outer shape of the first base substrate 10 is substantially the same as the outermost shape of the package body 5. The upper surface 10 a (the surface on the + Z axis direction side) of the first base substrate 10 defines the bottom of the cavity C.

  As shown in FIG. 4, the outer shape of the second base substrate 11 is substantially the same as the outer shape of the first base substrate 10. The second base substrate 11 has a frame shape that opens in the thickness direction. The inner peripheral surface 11a of the second base substrate 11 has a shape with rounded four corners in plan view. The inner peripheral surface 11a of the second base substrate 11 defines a part (lower part) of the side portion of the cavity C (see FIG. 3).

  As shown in FIG. 3, the second base substrate 11 is disposed on the upper surface 10 a of the first base substrate 10. The second base substrate 11 is integrated with the first base substrate 10. For example, the second base substrate 11 is coupled to the first base substrate 10 by sintering or the like.

  As shown in FIG. 4, the second base substrate 11 is provided with mounting portions 14 </ b> A and 14 </ b> B that protrude inward in the width direction. The mounting portions 14 </ b> A and 14 </ b> B are located at the center in the longitudinal direction of the second base substrate 11.

  The outer shape of the third base substrate 12 is substantially the same as the outer shape of the second base substrate 11. The third base substrate 12 has a frame shape that opens in the thickness direction. The inner peripheral surface 12a of the third base substrate 12 defines a part (vertical center) of the side portion of the cavity C (see FIG. 3).

  As shown in FIG. 3, the third base substrate 12 is disposed on the upper surface of the second base substrate 11. The third base substrate 12 is integrated with the second base substrate 11. For example, the third base substrate 12 is coupled to the second base substrate 11 by sintering or the like.

  As shown in FIG. 4, the seal ring 13 has conductivity. The outer shape of the seal ring 13 is smaller than the outer shape of the third base substrate 12. The seal ring 13 has a frame shape opening in the thickness direction. The inner peripheral surface 13a of the seal ring 13 defines a part (upper part) of the side portion of the cavity C (see FIG. 3).

  As shown in FIG. 3, the seal ring 13 is bonded to the upper surface of the third base substrate 12. For example, the seal ring 13 is bonded to the third base substrate 12 by baking with a brazing material such as silver brazing or a solder material. The seal ring 13 may be bonded to a metal bonding layer formed on the upper surface of the third base substrate 12 by welding or the like. For example, examples of the method for forming the metal bonding layer include electrolytic plating, electroless plating, vapor deposition, and sputtering.

For example, as a material for forming the seal ring 13, a nickel-based alloy or the like can be given. Specifically, the material for forming the seal ring 13 may be selected from Kovar, Elinvar, Invar, 42-alloy, and the like. In particular, it is preferable to select a material close to the thermal expansion coefficient of the material forming the first base substrate 10 and the second base substrate 11 as the material forming the seal ring 13. For example, when the forming material of the first base substrate 10 and the second base substrate 11 is alumina having a thermal expansion coefficient of 6.8 × 10 ⁻⁶ / ° C., the forming material of the seal ring 13 has a thermal expansion coefficient of 5. It is preferable to use a Kovar of 2 × 10 ⁻⁶ / ° C. or a 42-alloy having a thermal expansion coefficient of 4.5 to 6.5 × 10 ⁻⁶ / ° C.

  The sealing plate 6 has conductivity. The outer shape of the sealing plate 6 is substantially the same as the outer shape of the seal ring 13. The lower surface 6 a (the surface on the −Z axis direction side) of the sealing plate 6 defines the upper portion of the cavity C.

  The sealing plate 6 is joined to the upper end of the seal ring 13. For example, the sealing plate 6 may be joined by seam welding, laser welding, ultrasonic welding, or the like by contacting a roller electrode. In addition, from the viewpoint of more reliably joining the sealing plate 6 and the seal ring 13, a bonding layer such as nickel and gold that is familiar to each other is attached to the outer peripheral portion of the lower surface 6 a of the sealing plate 6 (that is, with the seal ring 13. It is preferable to form each on the joining surface) and the upper end of the seal ring 13 (that is, the joining surface with the sealing plate 6).

  The cavity C includes an upper surface 10 a of the first base substrate 10, an inner peripheral surface 11 a of the second base substrate 11, an inner peripheral surface 12 a of the third base substrate 12, an inner peripheral surface 13 a of the seal ring 13, and a lower surface 6 a of the sealing plate 6. It is divided by. That is, the inside of the piezoelectric vibrator 1 includes the upper surface of the first base substrate 10, the inner peripheral surface 11a of the second base substrate 11, the inner peripheral surface 12a of the third base substrate 12, the inner peripheral surface 13a of the seal ring 13, and the sealing. The plate 6 is hermetically sealed by the lower surface 6a.

  As shown in FIG. 4, a pair of electrode pads 20 </ b> A and 20 </ b> B, which are connection electrodes to the piezoelectric vibrating reed 3, are formed on the upper surfaces of the mounting portions 14 </ b> A and 14 </ b> B of the second base substrate 11. On the other hand, a pair of external electrodes 21A and 21B separated from each other in the longitudinal direction are formed on the lower surface of the first base substrate 10. For example, the electrode pads 20A and 20B and the external electrodes 21A and 21B are a single layer film made of a single metal formed by vapor deposition, sputtering, or the like, or a stacked film in which different metals are stacked. The electrode pads 20A and 20B and the external electrodes 21A and 21B are electrically connected to each other via a wiring (not shown).

[Piezoelectric vibrating piece]
As shown in FIG. 5, the piezoelectric vibrating piece 3 includes a piezoelectric plate 30 and electrodes (not shown) formed on the piezoelectric plate 30.

  The piezoelectric plate 30 is made of a piezoelectric material. In the present embodiment, the piezoelectric plate 30 is made of quartz. The piezoelectric plate 30 may be formed of a piezoelectric material such as lithium tantalate and lithium niobate.

  The piezoelectric plate 30 includes a pair of vibrating arm portions 31 and 32 (a first vibrating arm portion 31 and a second vibrating arm portion 32), a base portion 35 that connects base ends of the pair of vibrating arm portions 31 and 32, and a base portion. 35 and a pair of support arm portions 33 and 34 (a first support arm portion 33 and a second support arm portion 34) disposed on the outer side in the width direction of the pair of vibrating arm portions 31 and 32. ing. When viewed from the Z-axis direction, the piezoelectric plate 30 has a substantially line-symmetric shape with the central axis O along the Y-axis direction as the symmetry axis, except for the etching residue.

[Vibrating arm]
The vibrating arm portions 31 and 32 have a length in the Y-axis direction. The vibrating arm portions 31 and 32 extend from the base portion 35 toward the + Y axis direction. The vibrating arm portions 31 and 32 are arranged in parallel along the X-axis direction. The vibrating arms 31 and 32 vibrate with the base 35 as a fixed end and the tip as a free end. The vibrating arm portions 31 and 32 include main body portions 31 </ b> A and 32 </ b> A positioned on the base 35 side and weight portions 31 </ b> B and 32 </ b> B positioned on the distal end side of the vibrating arm portions 31 and 32.

  Groove portions 37 are formed in the main body portions 31A and 32A. The groove portion 37 is recessed inward in the thickness direction on both main surfaces (both surfaces in the thickness direction) of the main body portions 31A and 32A. The groove portion 37 extends over the longitudinal direction of the main body portions 31A and 32A.

  The main body portions 31A and 32A are provided with excitation electrodes (not shown) that vibrate the vibrating arm portions 31 and 32 in the width direction when a predetermined drive voltage is applied.

  When viewed from the Z-axis direction, the weight portions 31B and 32B have a rectangular shape having a length in the Y-axis direction. As seen from the thickness direction of the vibrating arm portions 31 and 32, the widths of the weight portions 31 </ b> B and 32 </ b> B are constant in the longitudinal direction of the vibrating arm portions 31 and 32.

  In the X-axis direction, the weight portions 31B and 32B are wider than the main body portions 31A and 32A. Thereby, while increasing the mass of the front-end | tip of the vibrating arm parts 31 and 32, the moment of inertia at the time of a vibration can be increased. Therefore, the vibrating arm portions 31 and 32 can be shortened compared to a piezoelectric vibrating piece that does not have the weight portions 31B and 32B.

  Although not shown, weight parts 31B and 32B are formed with a weight metal film formed integrally with the excitation electrode. The weight metal film increases the mass of the tips of the vibrating arm portions 31 and 32. The weight metal film suppresses an increase in resonance frequency when the vibrating arm portions 31 and 32 are shortened.

[Supporting arm]
The support arm portions 33 and 34 are L-shaped when viewed from the Z-axis direction. The support arm portions 33 and 34 are disposed outward in the width direction of the base portion 35 and the vibrating arm portions 31 and 32 (main body portions 31A and 32A). Specifically, the support arm portions 33 and 34 protrude from the both side surfaces of the base portion 35 in the width direction toward the outside in the width direction, then protrude toward the + Y axis direction, and the vibrating arm portions along the Y axis direction. 31 and 32 extend in parallel.

  Mounted portions 33a and 34a for mounting the piezoelectric vibrating reed 3 on the package body 5 (see FIG. 2) are provided on the support arm portions 33 and 34, respectively. The mount portions 33a and 34a are disposed near the tips of the support arm portions 33 and 34.

  In FIG. 5 (FIG. 2), for the sake of convenience, the regions of the mount portions 33a and 34a are partitioned by virtual lines (two-dot chain lines). Although not shown, the mount portions 33a and 34a are each provided with two systems of mount electrodes. The two mount electrodes are electrically connected to the two excitation electrodes by the two lead electrodes.

[Etching residue]
An etching residue is formed on the outer peripheral surface of the piezoelectric vibrating piece 3 due to etching anisotropy of crystal. In FIG. 5 (FIG. 2), for the sake of convenience, the etching residue 40E formed on the fork portion 40 (first fork portion) of the pair of vibrating arm portions 31 and 32, and the fork portion 41 of the support arm portions 33 and 34 and the base portion 35. , 42 (second fork), the etching residues 41E, 42E formed in an exaggerated manner. When viewed from the Z-axis direction, the outer shapes of the etching residues 40E, 41E, and 42E are inclined so as to be positioned on the + Y-axis direction side toward the −X-axis direction side.

  The first fork 40 and the first fork 40 are shown in a cross-sectional view parallel to the longitudinal direction of the vibrating arm portions 31 and 32 and perpendicular to the width direction of the pair of vibrating arm portions 31 and 32 (hereinafter sometimes simply referred to as “cross-sectional view”). The second fork portions 41 and 42 are formed with protruding portions 45 (see FIG. 6) that protrude toward the distal ends of the vibrating arm portions 31 and 32. Hereinafter, a sectional view of the second fork 41 (specifically, the fork of the first support arm 33 and the base 35) will be described. In addition, about the cross-sectional view of the 1st fork part 40 and the 2nd fork part 42, since it has the same shape as the cross-sectional view of the 2nd fork part 41, the description is abbreviate | omitted.

<Projection (second projection)>
FIG. 6 is a cross-sectional view of the second fork 41.
As shown in FIG. 6, in a cross-sectional view of the second fork 41, the protrusion 45 (second protrusion) has a triangular shape having an apex angle on the + Y axis direction side. The protruding portion 45 is an inclined surface 45a that is inclined with respect to one surface in the thickness direction of the second fork 41 so that the inner side in the thickness direction of the second fork 41 (thickness direction of the base 35) is located on the + Y-axis direction side. have. The protrusion 45 has an isosceles triangle shape having an inclined surface 45a having substantially the same length as the hypotenuse.

  The protrusion 45 is disposed on the surface of the second fork 41 on the + Y axis direction side. The second fork 41 is disposed at the center in the thickness direction (Z-axis direction). In the cross-sectional view of the second fork 41, the protrusion 45 has a line-symmetric shape with the center line J <b> 1 in the thickness direction of the second fork 41 as the axis of symmetry.

<Step part>
A step 46 (second step) is formed in a portion opposite to the protrusion 45 in the cross-sectional view of the second fork 41 (that is, a portion on the −Y axis direction side of the second fork 41). ing. In the cross-sectional view of the second fork 41, the step on the side of the step 46 can be stepped to balance the portion on the opposite side of the protrusion 45, so that the entire cross-section can be balanced. . In a cross-sectional view of the second fork 41, the stepped portion 46 is inclined with respect to the one surface 41 a of the second fork 41 so that the inner side in the thickness direction of the second fork 41 is located closer to the protrusion 45. A first inclined portion 46a, a second inclined portion 46b that is inclined with respect to the other surface 41b of the second forked portion 41 so that the inner side in the thickness direction of the second forked portion 41 is located on the opposite side of the protruding portion 45, A connecting portion 46c that connects the first inclined portion 46a and the second inclined portion 46b.

  Specifically, the first inclined portion 46a has a linear shape that is inclined so as to be positioned on the + Y-axis direction side from the −Y-axis direction end of the one surface 41a of the second fork portion 41 toward the −Z-axis direction side. The −Z-axis direction end of the first inclined portion 46a is located on the + Z-axis direction side with respect to the central axis J1.

  The second inclined portion 46b is linearly inclined so as to be positioned closer to the −Y-axis direction side from the −Y-axis direction end of the other surface 41b of the second fork portion 41 toward the + Z-axis direction side. The + Z-axis direction end of the second inclined portion 46b is located on the −Z-axis direction side with respect to the central axis J1. In the Y-axis direction, the −Y-axis direction end of the other surface 41 b of the second fork part 41 is disposed at substantially the same position as the −Y-axis direction end of the one surface 41 a of the second fork part 41.

  The connecting portion 46c connects the −Z-axis direction end of the first inclined portion 46a and the + Z-axis direction end of the second inclined portion 46b. The connecting portion 46c extends in a straight line so as to be positioned closer to the -Y-axis direction side from the -Z-axis direction end of the first inclined portion 46a to the -Y-axis direction side, and the + Z-axis of the second inclined portion 46a It reaches the end of the direction.

  An imaginary line passing through the −Y-axis direction end of the other surface 41b of the second fork 41 and the −Y-axis direction end of the one surface 41a of the second fork 41 in a cross-sectional view of the second fork 41 is J2. In a cross-sectional view of the second fork portion 41, the outer shape of the stepped portion 46 has a rotationally symmetric (two-fold symmetry) shape around the intersection Pc between the central axis J1 and the virtual line J2.

  In a cross-sectional view of the second fork 41, the intersection of the first inclined portion 46a and the connecting portion 46c is the first inflection point P1, and the intersection of the second inclined portion 46b and the connecting portion 46c is the second inflection point P2. And The first inflection point P <b> 1 and the second inflection point P <b> 2 overlap the protrusion 45 in the thickness direction of the second fork 41. Specifically, the first inflection point P1 is located between the + Z-axis direction end Q1 of the inclined surface 45a of the protrusion 45 and the central axis J1 in the Z-axis direction. On the other hand, the second inflection point P2 is located between the −Z-axis direction end Q2 of the inclined surface 45a of the protrusion and the central axis J1.

[Connection state of piezoelectric vibrating piece]
As shown in FIG. 2, the piezoelectric vibrating reed 3 is accommodated in the cavity C of the hermetically sealed package 2. The support arm portions 33 and 34 are electrically and mechanically joined to the two electrode pads 20A and 20B provided on the mounting portions 14A and 14B, respectively, via a conductive adhesive. The vibrating arm portions 31 and 32 are supported via the base portion 35. Although not shown, the two mount electrodes are electrically connected to the electrode pads 20A and 20B, respectively.

  Metal bumps may be used as the conductive bonding material for bonding the support arm portions 33 and 34 and the electrode pads 20A and 20B. The metal bump has fluidity in the early stage of bonding and has a property of solidifying and expressing bonding strength in the later stage of bonding. The conductive adhesive also has the same properties as the metal bumps.

  Although not shown, when a predetermined voltage is applied to the external electrodes 21A and 21B (see FIG. 3), current flows through the two excitation electrodes formed in the main body portions 31A and 32A, respectively, and the two excitation electrodes. An electric field is generated between them. For example, the vibrating arm portions 31 and 32 vibrate at a predetermined resonance frequency in a direction close to or away from each other (X-axis direction) by an inverse piezoelectric effect caused by an electric field generated between two systems of excitation electrodes. For example, the vibration of the vibrating arm portions 31 and 32 can be used as a time source, a timing source of control signals, a reference signal source, or the like.

[Method for manufacturing piezoelectric vibrating piece]
Next, an example of a method for manufacturing the piezoelectric vibrating piece 3 of this embodiment will be described.
First, a wafer is prepared. For example, a crystal Lambert rough is sliced into a wafer having a certain thickness.
Next, a mask (hereinafter referred to as “outer shape mask”) having a shape corresponding to the outer shape of the piezoelectric plate 30 (see FIG. 5) and the frame portion (not shown) is formed on both surfaces in the thickness direction of the wafer by photolithography. To do. Next, the wafer is wet etched. As a result, regions not masked by the outer shape mask are selectively removed to form outer shapes of the piezoelectric plate 30 (see FIG. 5) and the frame portion (not shown) (outer shape forming step).

  FIG. 7 is a cross-sectional view corresponding to FIG. 6 showing an example of the arrangement of the outer shape masks 51 and 52 formed on both surfaces in the thickness direction of the wafer 50 in the outer shape forming step. That is, FIG. 7 is a cross-sectional view showing a portion of the wafer 50 before the formation of the second fork 41 (see FIG. 6). In FIG. 7, the cross-sectional hatch of the wafer 50 is omitted for convenience.

  As shown in FIG. 7, the + Y-axis direction end of the outer shape mask 51 (hereinafter referred to as “first mask 51”) formed on one surface 50 a of the wafer 50 in the Y-axis direction is formed on the other surface 50 b of the wafer 50. The outer shape mask (hereinafter referred to as “second mask 52”) has substantially the same position as the + Y-axis direction end. On the other hand, in the Y-axis direction, the −Y-axis direction end of the first mask 51 is a position on the + Y-axis direction side of the −Y-axis direction end of the second mask 52.

In the cross-sectional view of FIG. 7, the deviation in the Y-axis direction between the −Y-axis direction end of the first mask 51 and the −Y-axis direction end of the second mask 52 is L, the thickness of the wafer 50 is t, and the cut angle is K. To do. Here, the cut angle K means an angle with respect to the crystal axis when the piezoelectric plate 30 is cut out from the wafer 50. The deviation L, the thickness of the wafer 50, and the cut angle K are
0 <L <2 × t × tanK
Meet.

  If L = 0, it is the same as the existing design. On the other hand, in the case of L ≧ 2 × t × tanK, there is a possibility that the cross-sectional shape of the second fork becomes an unbalanced shape in the thickness direction of the second fork. In contrast, according to the present embodiment, the cross-sectional shape of the second fork 41 (see FIG. 6) is balanced in the thickness direction of the second fork 41 by satisfying 0 <L <2 × t × tanK. It can be set as a good shape.

  For example, the wet etching process is performed by immersing the wafer 50 on which the outer masks 51 and 52 are formed in a chemical solution. Thereby, the wet etching process can proceed simultaneously from both surfaces 50a and 50b of the wafer 50.

  7, the + Y-axis direction end of the first mask 51 is substantially the same position as the + Y-axis direction end of the second mask 52 in the Y-axis direction. Therefore, as shown in FIG. 6, the cross section after etching (the portion of the second fork 41 on the + Y-axis direction side, the protruding portion 45) has a line-symmetric shape with the center line J1 as the axis of symmetry.

  On the other hand, in the Y-axis direction, the −Y-axis direction end of the first mask 51 is a position on the + Y-axis direction side of the −Y-axis direction end of the second mask 52 in the cross-sectional view of FIG. Here, due to the etching anisotropy of the quartz crystal, the wafer 50 has a property that, on the −Y axis direction side, the −Z axis direction side is more easily etched than the + Z axis direction side.

  In the present embodiment, the second mask 52 on the side that is easily etched is extended to the −Y axis direction side from the first mask 51 on the side that is difficult to etch. Thereby, on the −Y axis direction side of the wafer 50, the etching rate of the portion on the + Z axis direction side and the portion on the −Z axis direction side is adjusted to be balanced.

  On the −Y-axis direction side of the wafer 50, a portion on the + Z-axis direction side is a first inclined portion 46 a (see FIG. 6) that is inclined along the imaginary line V forming the cut angle K. On the other hand, on the −Y-axis direction side of the wafer 50, a portion on the −Z-axis direction side becomes a second inclined portion 46 b (see FIG. 6) that is inclined along the imaginary line V forming the cut angle K. As shown in FIG. 6, the wet etching process is finished in a state where the connecting portion 46c (that is, the inflection points P1 and P2 of the step portion 46) remains.

  Thereby, the cross section after etching (the portion on the −Y axis direction side of the second fork portion 41) becomes a stepped portion 46 having a two-fold symmetrical shape with the intersection Pc as the center. By adjusting the etching time, the first inflection point P1 is positioned between the + Z-axis direction end Q1 of the inclined surface 45a of the protrusion 45 and the central axis J1 in the Z-axis direction. On the other hand, the second inflection point P2 is positioned between the −Z-axis direction end Q2 of the inclined surface 45a of the protrusion and the central axis J1.

  And after an external shape formation process, an electrode formation process, a weight metal film formation process, a frequency adjustment process, and an individualization process are performed in order. Thereby, the piezoelectric vibrating piece 3 can be manufactured from the wafer 50.

  As described above, the piezoelectric vibrating reed 3 and the piezoelectric vibrator 1 according to this embodiment include the pair of vibrating arm portions 31 and 32 and the base portion 35 that connects the base ends of the pair of vibrating arm portions 31 and 32. And the fork portion 40 of the pair of vibrating arm portions 31 and 32 has vibration in a cross-sectional view parallel to the longitudinal direction of the vibrating arm portions 31 and 32 and perpendicular to the width direction of the pair of vibrating arm portions 31 and 32. A projecting portion 45 projecting to the distal end side of the arm portions 31 and 32 is formed, and a step portion 46 is formed on a portion opposite to the projecting portion 45 in the cross-sectional view. The first inclined portion 46a is inclined with respect to one surface of the base portion 35 so that the inner side in the thickness direction of the base portion 35 is located on the side of the protruding portion 45, and on the opposite side of the protruding portion 45 toward the inner side in the thickness direction of the base portion 35. A second inclined portion 46b that is inclined with respect to the other surface of the base portion 35 so as to be positioned, and a first inclined portion 46a and a connecting portion 46c for connecting the second inclined portion 46b, and a.

According to the present embodiment, the cross-sectional shape of the fork portion 40 of the pair of vibrating arm portions 31 and 32 is formed by forming the stepped portion 46 in the portion opposite to the protruding portion 45 in the cross-sectional view. The piezoelectric vibrating piece 3 can have a well-balanced shape in the thickness direction. Therefore, occurrence of vibration leakage and reduction in impact resistance can be suppressed.
By the way, when the wafer 50 made of a piezoelectric material such as quartz is subjected to wet etching, a deformed portion made of a natural crystal plane of the piezoelectric material is formed as an etching residue in a portion opposite to the protruding portion 45 in the sectional view. There is. The surface of the deformed portion is a surface inclined with respect to the main surfaces 50 a and 5 b of the wafer 50. Therefore, according to the present embodiment, the first inclined portion 46a and the second inclined portion 46b (that is, the inclination of the step portion 46) can be formed using the property (etching anisotropy) of the piezoelectric material. It is suitable for improving the production efficiency.

  In the present embodiment, in the cross-sectional view, the intersection between the first inclined portion 46a and the connecting portion 46c is the first inflection point P1, and the intersection between the second inclined portion 46b and the connecting portion 46c is the second inflection. When the point P <b> 2 is set, the first inflection point P <b> 1 and the second inflection point P <b> 2 overlap the protruding portion 45 in the thickness direction of the base portion 35.

  According to the present embodiment, the first inflection point P <b> 1 and the second inflection point P <b> 2 are displaced from the protrusion 45 in the thickness direction of the base 35 in the cross-sectional view, as compared with the pair of vibrating arm portions. The cross-sectional shapes of the fork portions 31 and 32 can be made to have a more balanced shape in the thickness direction of the piezoelectric vibrating piece 3. Therefore, the occurrence of vibration leakage and the reduction in impact resistance can be more reliably suppressed.

  Moreover, in this embodiment, it is further provided with a pair of support arm parts 33 and 34 which are connected to the base part 35 and are arranged on the outer side in the width direction of the pair of vibrating arm parts 31 and 32. The second fork portions 41 and 42 of the portions 33 and 34 and the base portion 35 are formed with second projecting portions 45 projecting toward the distal ends of the vibrating arm portions 31 and 32, and the second projecting portions 45 in the cross-sectional view. A second step portion 46 is formed on the opposite side to the portion.

  According to the present embodiment, the second step portion 46 is formed on the opposite side of the second protrusion 45 in the cross-sectional view, so that the cross-sectional shape of the second fork portions 41 and 42 is changed to the piezoelectric shape. It can be set as a well-balanced shape in the thickness direction of the resonator element 3. Therefore, in the side arm type piezoelectric vibrating piece 3, it is possible to suppress the occurrence of vibration leakage and the reduction in impact resistance. In particular, the side arm type piezoelectric vibrating piece 3 has more fork portions 40, 41, and 42 than the vibrating piece that does not include the support arm portions 33 and 34. Therefore, the occurrence of vibration leakage and a reduction in shock resistance are caused. It is suitable for suppression.

The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, in the above-described embodiment, the piezoelectric vibrating piece 3 is a so-called side arm type vibrating piece in which the support arm portions 33 and 34 are disposed outside the vibrating arm portions 31 and 32. However, the present invention is not limited to this, and the piezoelectric vibrating piece may be a so-called center arm type vibrating piece in which one supporting arm portion is disposed between a pair of vibrating arm portions, and includes a supporting arm portion. It may be a vibrating piece. Moreover, the groove part does not need to be formed in the vibrating arm part.

  Moreover, in the said embodiment, the protrusion part 45 was formed in each of the 1st fork part 40 and the 2nd fork part 41,42 by the said cross sectional view. However, the present invention is not limited to this, and the protrusion 45 may be formed on either the first fork 40 or the second fork 41 or 42 in the cross-sectional view. That is, it is only necessary that the protrusion 45 be formed on at least one of the first fork 40 and the second fork 41 and 42 in the cross-sectional view.

  In the embodiment, the first inflection point P <b> 1 and the second inflection point P <b> 2 overlap the protrusion 45 in the thickness direction of the base 35 in the cross-sectional view. However, the present invention is not limited to this, and the first inflection point P <b> 1 and the second inflection point P <b> 2 may be displaced from the protrusion 45 in the thickness direction of the base 35 in the cross-sectional view.

Further, in the above-described embodiment, in the Y-axis direction in the cross-sectional view of the second fork 41, the −Y-axis direction end of the other surface 41 b of the second fork 41 is −Y of the one surface 41 a of the second fork 41. It was disposed at substantially the same position as the axial end (see FIG. 6). However, the present invention is not limited to this, and in the Y-axis direction, the −Y-axis direction end of the other surface 41 b of the second fork 41 may be displaced from the −Y-axis direction end of the one surface 41 a of the second fork 41. .
Moreover, in the said embodiment, the cross-sectional view of the 2nd fork part 41 WHEREIN: The connection part 46c had comprised the linear form which inclines so that it may be located in the -Y-axis direction side as the -Z-axis direction side (refer FIG. 6). ). However, the present invention is not limited to this, and the connecting portion may have a linear shape along the central axis J1 in a cross-sectional view of the second fork.
In the following modifications, the same reference numerals are given to the same components as those in the above embodiment, and the detailed description thereof is omitted. 8 to 12, reference numerals 145, 245, 345, 445, and 545 denote projecting portions, and 146c, 246c, 346c, 446c, and 546c denote connecting portions, respectively.

[First Modification]
For example, as shown in FIG. 8, in the cross-sectional view of the second fork 141, the −Y axis direction end of the other surface 141 b of the second fork 141 in the Y-axis direction is the surface 141 a of the second fork 141. It may be located on the −Y axis direction side from the −Y axis direction end. In this modification, the imaginary line J2 is inclined so as to be positioned on the −Y axis direction side toward the −Z axis direction side. For example, in this modification, in the outer shape forming step, the deviation L (see FIG. 7) in the Y-axis direction between the −Y-axis direction end of the first mask 51 and the −Y-axis direction end of the second mask 52 is performed as described above. By making it larger than the size of the form, the outer shape of the stepped portion 146 can be obtained.

[Second Modification]
For example, as shown in FIG. 9, in the Y-axis direction, the −Y-axis direction end of the other surface 241 b of the second fork portion 241 is the surface of the first fork 241 a of the second fork portion 241 in the Y-axis direction. It may be located on the + Y-axis direction side from the −Y-axis direction end. In this modification, the imaginary line J2 is inclined so as to be located on the + Y-axis direction side toward the −Z-axis direction side. For example, in this modification, in the outer shape forming step, the deviation L (see FIG. 7) in the Y-axis direction between the −Y-axis direction end of the first mask 51 and the −Y-axis direction end of the second mask 52 is performed as described above. By making it smaller than the size of the form, the outer shape of the step portion 246 can be obtained.

[Third Modification]
For example, as shown in FIG. 10, in the cross-sectional view of the second fork part 341, the connecting part 346c may have a linear shape overlapping the central axis J1. For example, in this modification, in the outer shape forming step, the wet etching process is finished when the etching on the + Z-axis direction side and the etching on the −Z-axis direction side are finished, so that the outer shape of the step portion 346 is obtained. Can do.

[Fourth Modification]
For example, as illustrated in FIG. 11, the length of the connecting portion 446 c may be longer than the length of the connecting portion 346 c according to the third modification in a cross-sectional view of the second fork portion 441. For example, in this modification, in the outer shape forming step, the deviation L (see FIG. 7) in the Y-axis direction between the −Y-axis direction end of the first mask 51 and the −Y-axis direction end of the second mask 52 is performed as described above. The outer shape of the step portion 446 can be made by making the size larger than the size of the form and ending the wet etching process when the etching on the + Z-axis direction side and the etching on the −Z-axis direction side pass.

[Fifth Modification]
For example, as shown in FIG. 12, the length of the connecting portion 546c may be shorter than the length of the connecting portion 346c according to the third modification in a cross-sectional view of the second fork portion 541. For example, in the present modification, in the outer shape forming step, a shift L (see FIG. 7) in the Y-axis direction between the −Y-axis direction end of the first mask 51 and the −Y-axis direction end of the second mask 52 is expressed as a second. The dimensions are the same as those of the modification. For example, in this modification, in the outer shape forming step, the deviation L (see FIG. 7) in the Y-axis direction between the −Y-axis direction end of the first mask 51 and the −Y-axis direction end of the second mask 52 is performed as described above. The outer shape of the stepped portion 546 can be obtained by making the size smaller than the size of the form and ending the wet etching process when the etching on the + Z-axis direction side and the etching on the −Z-axis direction side pass.

  In addition, the constituent elements in the above-described embodiments can be appropriately replaced with known constituent elements without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator 2 ... Package 3 ... Piezoelectric vibration piece 31 ... 1st vibration arm part (vibration arm part) 32 ... 2nd vibration arm part (vibration arm part) 33 ... 1st support arm part (support arm part) 34 ... 2nd support arm part (support arm part) 35 ... Base 40 ... 1st fork part (fork part) 41, 42 ... Fork part (2nd fork part) 45,145,245,345,445,545 ... Projection part (2nd protrusion part) 46,146,246,346,446,546 ... Step part (2nd step part) 46a, 146a, 246a, 346a, 446a, 546a ... 1st inclination part 46b, 146b, 246b, 346b, 446b, 546b ... 2nd inclination part 46c, 146c, 246c, 346c, 446c, 546c ... connection part P1 ... 1st inflection point P2 ... 2nd inflection point

Claims (5)

A piezoelectric vibrating piece including a pair of vibrating arm portions and a base portion that connects base ends of the pair of vibrating arm portions,
In a cross-sectional view that is parallel to the longitudinal direction of the vibrating arm portion and perpendicular to the width direction of the pair of vibrating arm portions, a fork portion that protrudes toward the distal end side of the vibrating arm portion at the fork of the pair of vibrating arm portions Formed,
In the cross-sectional view, a step portion is formed on a portion opposite to the protruding portion,
In the sectional view, the stepped portion is
A first inclined portion that is inclined with respect to one surface of the base portion so as to be located closer to the protruding portion toward the inner side in the thickness direction of the base portion;
A second inclined portion that is inclined with respect to the other surface of the base so that the inner side in the thickness direction of the base is located on the opposite side of the protruding portion;
A connecting portion connecting the first inclined portion and the second inclined portion;
A piezoelectric vibrating piece comprising: In the cross-sectional view, when the intersection of the first inclined portion and the connecting portion is a first inflection point, and the intersection of the second inclined portion and the connecting portion is a second inflection point,
2. The piezoelectric vibrating piece according to claim 1, wherein the first inflection point and the second inflection point overlap the protrusion in the thickness direction of the base portion. A pair of support arm portions connected to the base portion and disposed outward in the width direction of the pair of vibrating arm portions;
In the cross-sectional view, a second protrusion that protrudes toward the distal end side of the vibrating arm is formed on the second fork of the support arm and the base,
3. The piezoelectric vibrating piece according to claim 1, wherein a second step portion is formed in a portion opposite to the second projecting portion in the cross-sectional view. A pair of vibrating arm portions, a base portion that connects the base ends of the pair of vibrating arm portions, and a pair of support arm portions that are coupled to the base portion and disposed outward in the width direction of the pair of vibrating arm portions And a piezoelectric vibrating piece comprising:
A first fork of the pair of vibrating arms, a second of the support arm and the base in a cross-sectional view parallel to the longitudinal direction of the vibrating arms and perpendicular to the width direction of the pair of vibrating arms. At least one of the fork portion is formed with a protruding portion that protrudes toward the distal end side of the vibrating arm portion,
In the cross-sectional view, a step portion is formed on a portion opposite to the protruding portion,
In the sectional view, the stepped portion is
A first inclined portion that is inclined with respect to one surface of the base portion so as to be located closer to the protruding portion toward the inner side in the thickness direction of the base portion;
A second inclined portion that is inclined with respect to the other surface of the base so that the inner side in the thickness direction of the base is located on the opposite side of the protruding portion;
A connecting portion connecting the first inclined portion and the second inclined portion;
A piezoelectric vibrating piece comprising: The piezoelectric vibrating piece according to any one of claims 1 to 4,
A package containing the piezoelectric vibrating piece;
A piezoelectric vibrator comprising:

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