JP6632347B2 - Tuning fork type crystal vibrating element - Google Patents

Description

  The present invention describes a tuning-fork type crystal vibrating element (hereinafter abbreviated as “tuning fork element”) used for a reference signal source or a clock signal source, for example.

  FIG. 7 is a schematic plan view showing a tuning fork element of Related Art 1 (see Patent Document 1). Hereinafter, description will be made based on this drawing.

  The tuning fork element 910 of Related Art 1 includes a base 911, a pair of vibrating arms 912a and 912b extending in the same direction from the base 911, and a protrusion 913 provided between the vibrating arms 912a and 912b. And a slit 914 formed from the tip of the projection 913. The base 911, the vibrating arms 912a and 912b, the protrusion 913, and the slit 914 are formed by wet etching of quartz. The slit 914 serves to separate the electrode film when the electrode film is formed by a lift-off method.

  The projection 913 has a substantially isosceles triangular shape in plan view, with the base 911 side being the bottom side and the tip side being the apex. By forming the protrusion 913 in a triangular shape in this manner, the following advantages are obtained as compared with a case where the protrusion is formed in an elongated rod shape.

  Since the width of the protrusion 913 is large, the influence of excessive etching due to the variation in etching is small, the peeling of the etching resist film covering the protrusion 913 is suppressed, and the protrusion 913 due to impact during the manufacturing process is suppressed. Damage is reduced. Since the portion where the etching residue is generated is occupied by the projection 913, the etching residue generated at the root of the vibrating arms 912a and 912b can be reduced and equalized.

JP 2014-23134 A

  However, since the slit 914 needs a certain length L to separate the electrode film, it has to be formed not only in the protrusion 913 but also in the base 911. As a result, in the related art 1, the base 911 is damaged through the slit 914, and the impact resistance of the base 911 is reduced.

  If the base angle θ of the projection 913 is extremely large, the slit 914 can be accommodated in the projection 913. In this case, however, the distance between the protrusion 913 and the vibrating arms 912a and 912b is reduced, and the protrusion 913 and the vibrating arms 912a and 912b are partially integrated by the etching residue. The operation of the units 912a and 912b is adversely affected.

  Therefore, an object of the present invention is to provide a tuning fork element that can improve the shock resistance of a base portion while taking advantage of the fact that a projection between a pair of vibrating arms is made triangular.

The tuning fork element according to the present invention comprises:
A base, a pair of vibrating arms extending in the same longitudinal direction from the base, a protrusion protruding in the longitudinal direction from the base between the vibrating arms, and a longitudinal end from the tip of the protrusion. A tuning fork-type quartz vibrating element comprising: a first slit formed; and an electrode film formed on the base, on the pair of vibrating arms, and on the protrusions ,
The protrusions possess a triangular protrusion whose apex the tip side and bottom of the base side, and a square-shaped projection provided on until the distal end from the vertex side of the triangular protrusion,
Between the tip of the protrusion and one of the pair of vibrating arms and between the tip of the protrusion and the other of the pair of vibrators, at least one A second slit is formed,
The first and second slits are separating the electrode film,
It is characterized by the following.

  According to the present invention, the protrusion between the pair of vibrating arms is constituted by the base-side triangular protrusion and the tip-side square protrusion, so that the portion of the slit provided at the base is moved to the protrusion. Therefore, it is possible to reduce damage to the base portion through the slit while taking advantage of the triangular shape of the projection.

FIG. 2 is a plan view showing the tuning fork element of the first embodiment. 2A is a sectional view taken along the line IIa-IIa in FIG. 1, and FIG. 2B is a schematic sectional view showing a state where the tuning fork element of FIG. 1 is mounted on an element mounting member. FIG. 3A is a schematic plan view showing a modification of the tuning fork element of Embodiment 1, in which FIG. 3A is a first example and FIG. 3B is a second example. FIG. 4A is a schematic plan view illustrating a tuning fork element according to another embodiment. FIG. 4A illustrates a second embodiment, and FIG. 4B illustrates a third embodiment. FIG. 14 is a schematic plan view showing a tuning fork element according to a fourth embodiment. FIG. 6A is a schematic plan view showing the effect of the tuning fork element of the fourth embodiment. FIG. 6A is a comparative example (Embodiment 1), and FIG. It is a schematic plan view showing related art 1.

  Hereinafter, embodiments for implementing the present invention (hereinafter, referred to as “embodiments”) will be described with reference to the accompanying drawings. In this specification and the drawings, the same reference numerals are used for substantially the same components. Further, the shapes drawn in the drawings are drawn so as to be easily understood by those skilled in the art, and thus do not always match actual dimensions and ratios.

  FIG. 1 is a plan view showing the tuning fork element of the first embodiment. FIG. 2A is a sectional view taken along line IIa-IIa in FIG. FIG. 2B is a schematic cross-sectional view showing a state where the tuning fork element of FIG. 1 is mounted on an element mounting member. Hereinafter, description will be made based on these drawings.

  As shown in FIGS. 1 and 2A, the tuning fork element 10 of the first embodiment includes a base 11, a pair of vibrating arms 12a and 12b extending from the base 11 in the same longitudinal direction, and a vibrating arm 12a. , 12b, a protrusion 13 protruding in the longitudinal direction from the base 11 and a slit 14 formed in the longitudinal direction from a tip 130 of the protrusion 13. The protrusion 13 includes a triangular protrusion 131 having the base 11 side as the base 131a and the tip 130 side as the apex 131b, a square protrusion 132 provided from the apex 131b side of the triangular protrusion 131 to the tip 130, Having.

  The vibrating arms 12a and 12b extend from the base 11 in the same direction, and grooves 15a and 15b are provided along the extending direction. Weights 16a and 16b for frequency adjustment are provided at the tips of the vibrating arms 12a and 12b, respectively. The base 11, the vibrating arms 12a and 12b, the protrusion 13, the slit 14, and the weights 16a and 16b are made of a quartz vibrating piece 19 formed by wet etching of quartz. The tuning fork element 10 includes pad electrodes 21a and 21b, excitation electrodes 22a and 22b, frequency adjusting metal films 23a and 23b, wiring patterns 24a and 24b, in addition to the crystal vibrating piece 19.

  The triangular projection 131 has a substantially isosceles triangular shape in plan view, and two sides 131c and 131d sandwiching the base 131a are linear. The square projection 132 is substantially rectangular in plan view. The slit 14 plays a role in separating the electrode film when the electrode film is formed by the lift-off method so that the excitation electrode 22a and the excitation electrode 22b are not short-circuited.

  Next, the configuration of the tuning fork element 10 will be described in more detail.

  The base 11 is a flat plate having a substantially rectangular shape in plan view. The crystal vibrating piece 19 has a tuning fork shape in which the base 11, the vibrating arms 12a and 12b, the protrusion 13 and the weights 16a and 16b are integrated, and is manufactured by a film forming technique, a photolithography technique, and a wet etching technique. Is done. Further, a support arm may be provided which extends from the base 11 in the short direction of the vibrating arms 12a and 12b and further extends from the tip thereof in the longitudinal direction of the vibrating arms 12a and 12b.

  The grooves 15a and 15b are vibrated toward the tips of the vibrating arms 12a and 12b from the boundary with the base 11 two by two on the front and back of the vibrating arm 12a and two by two on the front and back of the vibrating arm 12b. The arm portions 12a and 12b are provided with a predetermined length in parallel with the longitudinal direction. In the first embodiment, two grooves 15a and 15b are provided on the front and back surfaces of the vibrating arm portion 12a and two grooves are provided on each of the front and back surfaces of the vibrating arm portion 12b. However, the number of grooves is not limited. For example, one may be provided on each of the front and back surfaces of the vibrating arm portion 12a, and one may be provided on each of the front and back surfaces of the vibrating arm portion 12b, or may be provided on only one of the front and back surfaces. An etching suppression pattern may be provided in the grooves 15a and 15b so as not to penetrate during wet etching.

  Excitation electrodes 22a are provided on both sides of the vibrating arm 12a so that the planes opposed to each other across the crystal have the same polarity, and the excitation electrodes 22b are provided inside the groove 15a on the front and back surfaces. Similarly, the vibrating arm portion 12b is provided with the excitation electrodes 22b on both side surfaces so that the planes opposed to each other across the crystal have the same polarity, and the excitation electrodes 22a are provided inside the groove portions 15b on the front and back surfaces. . Therefore, in the vibrating arm portion 12a, the excitation electrodes 22a provided on both side surfaces and the excitation electrodes 22b provided in the grooves 15a have different polarities, and in the vibration arm portion 12b, the excitation electrodes 22b provided on both side surfaces are provided. And the excitation electrode 22a provided in the groove 15b have different polarities.

  The base 11 is provided with pad electrodes 21a and 21b and wiring patterns 24a and 24b, and the weights 16a and 16b are provided with metal films 23a and 23b for frequency adjustment. The wiring pattern 24a electrically connects between the pad electrode 21a and the excitation electrode 22a, and the wiring pattern 24b electrically connects between the pad electrode 21b and the excitation electrode 22b. The pad electrode 21a, the excitation electrode 22a, the frequency adjusting metal film 23a, and the wiring pattern 24a are electrically connected to each other. The pad electrode 21b, the excitation electrode 22b, the metal film for frequency adjustment 23b, and the wiring pattern 24b are also electrically connected to each other.

  As shown in FIG. 2B, the tuning fork element 10 is fixed in a cantilever manner to the pad electrode 33 on the element mounting member 32 side via the pad electrodes 21a and 21b (FIG. 1) and the conductive adhesive 31. It is electrically connected at the same time. The element mounting member 32 on which the tuning fork element 10 is mounted is sealed by a lid member 34. For the sealing method, for example, gold-tin sealing, electric welding, or molten glass is used.

  Quartz crystals are trigonal. A crystal axis passing through the apex of the crystal is defined as a Z axis, and three crystal axes connecting ridges in a plane perpendicular to the Z axis are defined as an X axis, and a coordinate axis orthogonal to the X and Z axes is defined as a Y axis. Here, when the coordinate system including the X axis, the Y axis, and the Z axis is rotated around the X axis in, for example, a range of ± 5 degrees, the Y axis and the Z axis after rotation are respectively referred to as the Y ′ axis and the Y ′ axis. Let it be the Z 'axis. In this case, in the first embodiment, the longitudinal direction of the two vibrating arms 12a and 12b is the direction of the Y 'axis, and the short direction of the two vibrating arms 12a and 12b is the direction of the X axis. . In addition, a crystal plane whose normal is oriented in the + X-axis direction is a + X plane, and a crystal plane whose normal is oriented in the -X-axis direction is a -X plane.

  Next, the operation of the tuning fork element 10 will be described. When the tuning fork element 10 is caused to bend and vibrate, an alternating voltage is applied to the pad electrodes 21a and 21b. When an electrical state after application is instantaneously captured, the excitation electrodes 22b provided in the grooves 15a on the front and back of the vibrating arm 12a have a positive potential, and the excitation electrodes 22a provided on both side surfaces of the vibrating arm 12a The potential becomes negative, and an electric field is generated from positive to negative. At this time, the excitation electrodes 22a provided in the grooves 15b on the front and back of the vibrating arm 12b have a negative potential, and the excitation electrodes 22b provided on both side surfaces of the vibrating arm 12b have a positive potential, which is generated in the vibrating arm 12a. The polarity is opposite to the polarity, and an electric field is generated from plus to minus. The electric field generated by this alternating voltage causes expansion and contraction of the vibrating arms 12a and 12b, and a bending vibration mode having a predetermined resonance frequency is obtained.

  Next, the operation and effect of the tuning fork element 10 will be described.

  According to the tuning fork element 10, the protrusion 13 between the pair of vibrating arms 12 a and 12 b includes the triangular protrusion 131 on the base 11 side and the square protrusion 132 on the tip 130 side, so that the base of the slit 14 is formed. Since the portion provided on the projection 11 can be transferred to the projection 13, damage to the base 11 via the slit 14 can be reduced while taking advantage of the fact that the projection 13 has a triangular shape.

  That is, since the protrusion 13 has the triangular protrusion 131, the advantage of making the protrusion 13 triangular can be utilized as it is. In addition, by providing the quadrangular projection 132 on the vertex 131b side of the triangular projection 131, all or a part of the portion 914a formed in the base 911 of the slit 914 shown in FIG. Can be moved to

  Furthermore, when the slits 14 are formed only in the protrusions 13 (ie, when all the portions 914a of the slits 914 shown in FIG. 7 are moved to the protrusions), the base 11 has no fragile parts and the mechanical strength increases. Thus, damage to the base 11 through the slit 14 can be further reduced.

  Next, a modified example of the tuning fork element 10 will be described. FIG. 3 is a schematic plan view showing a modification of the tuning fork element of the first embodiment. FIG. 3A is a first example, and FIG. 3B is a second example. In the drawings after FIG. 3, illustration of electrodes and weight portions is omitted.

  In the tuning fork element 10 'of the first example shown in FIG. 3A, the triangular projection 131' is smaller than that of the first embodiment, and the square projection 132 'is correspondingly larger. In other words, both ends of the bottom 131a 'are separated from the vibrating arms 12a and 12b. According to the tuning fork element 10 ', since the space between the triangular protrusion 131' and the vibrating arms 12a and 12b can be widely taken, the etching residue partially integrates the triangular protrusion 131 'and the vibrating arms 12a and 12b. Can be reduced.

  In the tuning fork element 10 ″ of the second example shown in FIG. 3B, the square projection 132 ″ is smaller than that of the first embodiment, and the portion 14 a of the slit 14 ″ is correspondingly smaller at the base. 11 is inside. However, the length of the portion 14a of the slit 14 "is shorter than that of the portion 914a of the slit 914 shown in FIG. According to the tuning fork element 10 ″, since the square projection 132 ″ is short, damage due to the impact of the square projection 132 ″ can be reduced.

  Other configurations, operations, and effects of the first and second modifications are the same as those of the first embodiment.

  Next, Embodiments 2 and 3 will be described. FIG. 4 is a schematic plan view showing a tuning fork element according to another embodiment. FIG. 4A shows a second embodiment, and FIG. 4B shows a third embodiment. In the first embodiment shown in FIG. 1, the two sides 131c and 131d sandwiching the bottom side 131a are linear. However, those sides are not limited to a straight line, but may be a curved line or a broken line. In the second and third embodiments, those sides are curved.

  In the tuning fork element 40 according to the second embodiment shown in FIG. 4A, the projection 43 has a triangular projection 431. The triangular projection 431 has a shape in which two sides 431c and 431d sandwiching the base 131a are convex outside the triangular projection 431. According to the tuning fork element 40, the area of the triangular projection 431 is increased by forming the triangular projection 431 into a triangular shape bulging outward, so that the peeling of the etching resist film covering the projection 43 can be further suppressed.

  In the tuning fork element 50 according to the third embodiment shown in FIG. 4B, the protrusion 53 has a triangular protrusion 531. The triangular projection 531 has a shape in which two sides 531c and 531d sandwiching the base 131a are concave outside the triangular projection 531. According to the tuning fork element 50, since the triangular projection 531 is formed into a triangle depressed inward, a wide space can be taken between the triangular projection 531 and the vibrating arms 12a and 12b. Partially integrating the arms 12a and 12b can be reduced.

  Other configurations, operations, and effects of the second and third embodiments are the same as those of the first embodiment.

  Next, a fourth embodiment will be described. FIG. 5 is a schematic plan view showing the tuning fork element of the fourth embodiment.

  The tuning fork element 60 according to the fourth embodiment includes a portion between the tip 130 of the protrusion 13 and the vibrating arm 12a and a portion between the tip 130 of the protrusion 13 and the vibrating arm 12b, in which the etching residue largely occurs. At least one other slit 64 is formed.

  In wet etching of quartz using hydrofluoric acid or the like, an etching residue adheres to quartz by anisotropic etching peculiar to quartz. In the square projection 132, a + X plane appears on the left side and a -X plane appears on the right side in the drawing. The etching residue generated on the −X plane is larger than the etching residue generated on the + X plane. That is, the etching residue in the −X axis direction from the tip 130 becomes larger than the etching residue in the + X axis direction from the tip 130. Therefore, in the fourth embodiment, another slit 64 is formed between the tip 130 and the vibrating arm 12b.

  By forming another slit 64 between the tip 130 and the vibrating arm 12b, the size of the etching residue in the −X-axis direction as viewed from the tip 130 of the projection 13 is in the + X-axis direction. It can approach the size of the etching residue. In other words, the rigidities of the etching residues at the roots of the vibrating arms 12a and 12b can be made the same. Therefore, in the fourth embodiment, abnormal vibration can be suppressed by improving the balance between the bending vibrations of the vibrating arms 12a and 12b, so that the electrical characteristics of the tuning fork element 60 can be improved. In addition, by providing the two slits 14 and 64, any one of the two slits can be used to separate the electrode film, so that the separation failure of the electrode film can be reduced.

  Next, effects of the tuning fork element 60 will be described with reference to the drawings. FIG. 6 is a schematic plan view showing the effect of the tuning fork element of the fourth embodiment. FIG. 6A shows a comparative example (first embodiment), and FIG. 6B shows a fourth embodiment. FIG. 6 shows an example of the etching residue, but the other drawings do not show the etching residue.

  In the tuning fork element 10 shown in FIG. 6A, another slit is not formed between the tip 130 and the vibrating arm 12b. Therefore, the etching residue Er1 in the −X axis direction from the tip 130 is larger than the etching residue El1 in the + X axis direction from the tip 130. That is, (the area of the etching residue Er1)> (the area of the etching residue El1) holds.

  On the other hand, in the tuning fork element 60 shown in FIG. 6B, another slit 64 is formed between the tip 130 and the vibrating arm 12b. Therefore, the size of the etching residue Er4 in the −X-axis direction from the tip 130 is close to the size of the etching residue El4 in the + X-axis direction from the tip 130. That is, (the area of the etching residue Er4) ≒ (the area of the etching residue El4) holds.

  Here, an example of the dimensions of the slits 14 and 64 will be described. The dimension parallel to the longitudinal direction of the vibrating arms 12a and 12b is defined as "length", and the dimension parallel to the lateral direction of the vibrating arms 12a and 12b is defined as "width". At this time, the slit 14 has a width of 10 to 18 μm and a length of 100 to 110 μm, and the slit 64 has a width of 4 to 15 μm and a length of 10 to 55 μm.

  Other configurations, operations, and effects of the fourth embodiment are the same as those of the first to third embodiments.

  The present invention has been described with reference to the above embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be added to the configuration and details of the present invention. Further, the present invention also includes a configuration in which some or all of the configurations of the above embodiments are appropriately combined with each other.

  The present invention can be used for any tuning fork element including a base, a vibrating arm, and a projection.

<First embodiment>
Reference Signs List 10 tuning fork element 11 base 12a, 12b vibrating arm 13 projection 130 tip 131 triangular projection 131a bottom 131b apex 131c, 131d side 132 square projection 14 slit 15a, 15b groove 16a, 16b weight 19 quartz vibrating piece 21a, 21b Pad electrode 22a, 22b Excitation electrode 23a, 23b Metal film for frequency adjustment 24a, 24b Wiring pattern 31 Conductive adhesive 32 Element mounting member 33 Pad electrode 34 Cover member El1, Er1 Etching residue <Modification 1>
10 'Tuning fork element 13' Projection 131 'Triangular projection 131a' Bottom 132 'Square projection <Modification 2>
10 ″ tuning fork element 13 ″ projection 132 ″ square projection 14 ″ slit 14a portion <second embodiment>
40 Tuning Fork Element 43 Projection 431 Triangular Projection 431c, 431d Side <Embodiment 3>
50 Tuning Fork Element 53 Projection 531 Triangular Projection 531c, 531d Side <Embodiment 4>
Reference Signs List 60 tuning fork element 64 slit El4, Er4 etching residue <Related art 1>
910 Tuning fork element 911 Base 912a, 912b Vibrating arm 913 Projection 914 Slit 914a Part L Slit length θ Base angle

Claims (5)

A base, a pair of vibrating arms extending in the same longitudinal direction from the base, a protrusion protruding in the longitudinal direction from the base between the vibrating arms, and a longitudinal end from the tip of the protrusion. A tuning fork-type quartz vibrating element comprising: a first slit formed; and an electrode film formed on the base, on the pair of vibrating arms, and on the protrusions ,
The protrusions possess a triangular protrusion whose apex the tip side and bottom of the base side, and a square-shaped projection provided on until the distal end from the vertex side of the triangular protrusion,
Between the tip of the protrusion and one of the pair of vibrating arms and between the tip of the protrusion and the other of the pair of vibrators, at least one A second slit is formed,
The first and second slits are separating the electrode film,
A tuning-fork type quartz vibrating element characterized by the above-mentioned. The first and second slits are formed only on the protrusions,
The tuning-fork type quartz vibrating element according to claim 1. The triangular projection has a shape in which two sides sandwiching the base are convex outside the triangular projection.
The tuning-fork type quartz vibrating element according to claim 1. The triangular projection has a shape in which two sides sandwiching the bottom are concave outside the triangular projection.
The tuning-fork type quartz vibrating element according to claim 1. The first and second slits cut off the electrode films formed on mutually facing surfaces of the pair of vibrating arms,
The tuning-fork type quartz vibrating element according to claim 1.

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