JP2021141368A - Piezoelectric device - Google Patents

Abstract

To provide a piezoelectric device that suppresses fluctuations in an oscillation frequency while supporting miniaturization.SOLUTION: A sound fork type piezoelectric vibration piece 2 is joined to the mounting pads 6a and 6b of the container 3 via a first metal bump 7a provided on the other end side of a base 20 and on the center side in the width direction of the base 20, and a second metal bump 7b provided on the tip side of a projecting portion 24. The first metal bump 7a and the second metal bump 7b are formed in the same shape in a plan view and have opposite sides. The areas of the first metal bump 7a and the second metal bump 7b in a plan view decrease as they are separated from the opposite sides to both outer sides in the width direction of the base 20.SELECTED DRAWING: Figure 2

Description

The present invention relates to piezoelectric devices.

With the miniaturization of mobile communication devices and the like, the piezoelectric devices such as crystal oscillators mounted on the mobile communication devices are also becoming smaller. For example, a surface-mounted tuning fork type crystal oscillator corresponding to miniaturization has a tuning fork type crystal vibrating piece, an insulating substrate (container) having a recess for accommodating the tuning fork, and a tuning fork in the recess by joining the container. The main component is a lid that airtightly seals the type crystal tuning fork.

When the tuning fork type crystal vibrating piece is ultrasonically bonded to a mounting pad provided in the recess of the container via a metal bump, the crystal oscillator can be downsized because reliable conductive bonding can be performed in a minute area. (For example, the external dimensions of a substantially rectangular parallelepiped crystal oscillator in a plan view are 1.6 mm in the long side direction and 1.0 mm in the short side direction). Such a bonded crystal unit is disclosed in, for example, Patent Documents 1 and 2.

Patent No. 5660162 Patent No. 5804029

The tuning fork type crystal vibrating piece in Patent Documents 1 and 2 includes a base portion, a pair of vibrating arms extending in the same direction from one end side of the base portion, and a joint portion protruding from the base portion. The joint portion is formed in an L-shape in a plan view with the base end portion of the joint portion as one side. The base end portion and the tip end portion of the joint portion are joint regions to be joined to the mounting pad of the container. Metal bumps having a circular or elliptical shape in a plan view are formed in these joint regions.

The tuning fork type crystal oscillator is mounted by joining an external connection terminal formed on the outer bottom surface of the container to an external substrate via solder. Therefore, stress due to expansion is generated in the container due to heat from electronic components mounted on the external substrate and heat from the surrounding environment. In particular, in an environment where a rapid temperature rise occurs in a short time such as reflow, the influence of the stress becomes large, and the stress is transmitted to the tuning fork type crystal vibrating piece, which may cause fluctuation (decrease) in the oscillation frequency. .. This will be described next.

FIG. 13 is a diagram showing a conventional tuning fork type crystal oscillator. In FIG. 13, the positions of the two elliptical bumps interposed between the crystal vibrating piece 2 and the container 31 are transparently displayed by a solid line. The container 31 has a substantially rectangular shape in a plan view, and when it expands in the extension direction of its short side (vertical direction shown on the left side of FIG. 13) due to the influence of the above-mentioned heat, the mounting pads 17a and 17b follow the expansion direction. A force is applied to each of the joints with the metal bumps 18a and 18b in a direction in which the distance between the two metal bumps 18a and 18b is increased. Therefore, stress is applied to the joints between the tuning fork type crystal vibrating piece 2 and the metal bumps 18a and 18b toward the inside (opposite inward arrows shown in FIG. 13) in the width direction (vertical direction in FIG. 13) of the base 20. Will work.

In this way, stress acts inward in the width direction of the base 20 on the other end side of the base 20 (the left end side of the base 20 in FIG. 13), so that both on the tip sides of the pair of vibrating arms 21 and 22 A force is applied in the direction of opening outward (backward outward arrow shown in FIG. 13). It is considered that this is substantially equivalent to the extension of the length of the vibrating arm (pseudo-extension of the vibrating arm), and the oscillation frequency of the tuning fork type crystal oscillator is lowered. This is because the oscillation frequency of the tuning fork type crystal vibrating piece is inversely proportional to the square of the length of the vibrating arm.

It is considered that the decrease in the oscillation frequency of the tuning fork type crystal oscillator due to the expansion of the container as described above is due to the shapes of the two metal bumps 18a and 18b in FIG. That is, since the metal bumps 18a and 18b are elliptical in a plan view, the stress acting on each joint between the tuning fork type crystal oscillator 2 and the metal bumps 18a and 18b generated by the expansion of the container 31 is applied. It is considered that the stress becomes uniform in each bump and the stress easily propagates to the base side of the tuning fork type crystal vibration piece 2.

The present invention has been made in view of this point, and an object of the present invention is to provide a piezoelectric device that suppresses fluctuations in oscillation frequency while coping with miniaturization.

The invention according to claim 1 for achieving the above object is a piezoelectric device in which a tuning fork type piezoelectric vibrating piece is conductively bonded to two mounting pads provided on a container via metal bumps.
The tuning fork type piezoelectric vibrating piece has a base portion, a pair of vibrating arms extending from one end side of the base portion in the first direction, and a protrusion extending from the other end side of the base portion in one of the second directions orthogonal to the first direction. With a part
The tuning fork type piezoelectric vibrating piece includes a first metal bump provided on the other end side of the base portion and on the central side in the second direction, and a second metal bump provided on the tip end side of the protruding portion. It is joined to the two mounting pads via
The first metal bump and the second metal bump are formed in the same shape in a plan view and have opposite sides, and the area in the plan view decreases as the distance from the facing sides to both outer sides in the second direction decreases. It is characterized by doing.

According to the above invention, when the first metal bump and the second metal bump have the same shape, the balance of stress acting on the joint portion between the tuning fork type piezoelectric vibrating piece and each bump can be maintained. Further, since the area in the plan view decreases as the first metal bump and the second metal bump are separated from the opposite side to both outer sides in the second direction (width direction of the base), the area in the metal bump is reduced. The opposite sides are joined more strongly. As a result, deformation of the other end side of the base portion (contraction toward the center side in the width direction of the base portion) due to expansion of the container is suppressed, so that the force of the tip side of the pair of vibrating arms to open outward is weakened. .. As a result, the pseudo stretching of the vibrating arm is suppressed, so that the decrease in the oscillation frequency can be suppressed.

Further, the invention according to claim 2 for achieving the above object is characterized in that the first metal bump has a larger area in a plan view than the second metal bump.

According to the above invention, since the first metal bump has a larger area in a plan view than the second metal bump, the central side in the width direction of the base is relatively strongly joined. As a result, the deformation of the other end side of the base portion due to the expansion of the container is suppressed, so that the force of the tip ends of the pair of vibrating arms to open outward is weakened. As a result, the pseudo stretching of the vibrating arm is suppressed, so that the decrease in the oscillation frequency can be further suppressed.

Further, in order to achieve the above object, the invention according to claim 3 is characterized in that the first metal bump and the second metal bump are formed in a substantially triangular shape in a plan view, and the bases of the triangles face each other. And.

According to the above invention, the first metal bump and the second metal bump are formed in a substantially triangular shape in a plan view, and the bases of the triangles face each other, so that the bases of the first metal bumps and the second metal bumps face each other on both outer sides in the second direction. As they are separated from each other, the areas of the first metal bump and the second metal bump in a plan view are continuously reduced. As a result, the decrease in the oscillation frequency can be further suppressed.

As described above, according to the present invention, it is possible to provide a piezoelectric device that suppresses fluctuations in the oscillation frequency while supporting miniaturization.

Schematic cross-sectional view of the crystal unit according to the embodiment of the present invention Schematic diagram of the upper surface of the crystal unit according to the embodiment of the present invention in a state where the lid is opened. Schematic diagram seen from one main surface side of the crystal vibrating piece according to the embodiment of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece according to the embodiment of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece showing another application example of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece showing another application example of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece showing another application example of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece showing another application example of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece showing another application example of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece showing another application example of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece showing another application example of the present invention. Schematic diagram seen from the other main surface side of the crystal vibrating piece showing another application example of the present invention. Top schematic of a conventional tuning fork crystal unit with the lid open

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4 by taking a tuning fork type crystal oscillator as an example as a piezoelectric device. In FIG. 1, the description of various electrodes formed on the tuning fork type crystal vibrating piece is omitted. Further, in FIG. 2, for convenience of explanation, the positions of the first bump and the second bump interposed between the tuning fork type crystal vibrating piece and the container are transparently displayed by a solid line. In FIG. 3, the contours of the first bump and the second bump are indicated by broken lines for reference.

The tuning fork type crystal oscillator 1 (hereinafter, abbreviated as crystal oscillator 1) in the present embodiment is a surface mount type crystal oscillator having a substantially rectangular parallelepiped package structure. In the present embodiment, the external dimensions in a plan view are 1.6 mm on the long side and 1.0 mm on the short side. The external dimensions of the crystal oscillator in a plan view are not limited to the dimensions, but are suitable for a small crystal oscillator having the same dimensions or less.

As shown in FIG. 1, the crystal oscillator 1 according to the embodiment of the present invention has a tuning fork type crystal vibrating piece 2 (hereinafter abbreviated as crystal vibrating piece 2) housed in a recess 5 of a container 3 made of an insulating material. Later, the flat plate-shaped lid 4 is joined to the open end of the container 3 so as to cover the recess 5, so that the crystal vibrating piece 2 is airtightly sealed in the internal space 8. The container 3 and the lid 4 are joined via a sealing material (not shown).

The container 3 is a box-shaped body made of an insulating material mainly composed of ceramics such as alumina, and in the present embodiment, it is formed by laminating three ceramic green sheets 3a, 3b, and 3c and integrally firing them. (See Fig. 1). The container 3 has a concave portion 5 having a rectangular shape in a plan view inside the frame-shaped bank portion 30. Then, as shown in FIGS. 1 and 2, a ceramic green sheet 3b as an intermediate layer projects toward the recess 5 on the upper surface 301 of the ceramic green sheet 3a, and a part of the ceramic green sheet 3b is a stage on which the crystal vibrating piece 2 is mounted. It constitutes a part. A sealing material (not shown) is formed in a frame shape on the upper surface 300 of the bank portion 30 in a plan view, and the sealing material corresponds to an outer peripheral portion of the lid 4.

As shown in FIG. 2, on the upper surface of the step portion along one short side of the rectangular recess 5 in a plan view, two mounting pads 6a and 6b conductively joined to the crystal vibrating piece 2 leave a gap between them. It is formed in parallel in the same state. The two mounting pads 6a and 6b are electrically connected to two external connection terminals 9 and 9 (only two are shown in FIG. 1) provided at both ends of the outer bottom surface 302 of the container 3 via internal wiring and vias (not shown). Is connected. These two mounting pads 6a and 6b are opposite to each other.

In the present embodiment, the two mounting pads 6a and 6b are formed by laminating gold on the upper surface of the tungsten metallized layer by using a technique such as plating. Molybdenum may be used instead of tungsten as the metallized layer.

The lid 4 is a metal lid having a rectangular shape in a plan view based on Kovar, and nickel-plated layers are formed on the front and back surfaces of the lid 4. Further, on the joint surface side of the lid 4 with the container 3, a brazing material made of metal is formed over the entire surface on the nickel-plated layer. In this embodiment, silver wax is used as the brazing material.

Next, the crystal vibrating piece in the present embodiment will be described with reference to FIGS. 3 to 4. For convenience of explanation, of the two opposing main surfaces (2a, 2b) of the crystal vibrating piece 2, the main surface facing the mounting pads 6a, 6b when mounted on the container 3 is designated as the back surface 2b, and the back surface is used. The main surface on the opposite side facing 2b will be described as the surface 2a. FIG. 3 shows a plan view seen from the front surface side (2a) of the crystal vibrating piece 2, and FIG. 4 shows a plan view seen from the back surface side (2b) of the crystal vibrating piece 2. In FIG. 3, for reference, the contours of the first bump and the second bump are indicated by broken lines.

As shown in FIGS. 3 to 4, the crystal vibrating piece 2 is a tuning fork-shaped artificial crystal, and is parallel to the base 20 from one end side 201 of the base 20 in the same direction (+ Y-axis direction shown in FIGS. 3 and 4). A pair of vibrating arms 21 and 22 extending from the base 20 and a protruding portion 24 extending from the other end 202 facing the one end side 201 of the base 20 in the width direction of the base 20 (+ X-axis direction shown in FIGS. 3 and 4) are provided. ing. The direction in which the pair of vibrating arms 21 and 22 extend is defined as the "first direction", and is the same direction as the Y-axis direction of the crystal axis of the artificial crystal (or the Y'direction inclined by several degrees from the Y-axis). It is said. Further, the direction orthogonal to the first direction is defined as the "second direction", which is the same direction as the X-axis direction of the crystal axis of the artificial quartz.

Wide portions 23, 23 (weight portions) that are wider than the arm width (the size of the arm in the second direction) of the vibrating arms 21 and 22 are formed on the tip side of each of the pair of vibrating arms 21 and 22. There is. The wide portions 23, 23 are integrally formed with the tip portions of the vibrating arms 21 and 22 via a widening portion (reference numeral omitted) that gradually widens toward the extension direction (first direction) of the vibrating arm. That is, the widened portion and the widened portions 23, 23 are integrally formed with the vibrating arm. Each corner of the wide portions 23, 23 on the tip side is chamfered (C-plane). The vibrating arms 21 and 22, the widening portion and the wide portion 23, 23 have a pair of side surfaces (reference numerals omitted) facing the pair of main surfaces 2a and 2b facing each other.

A long groove is formed on each of the front and back main surfaces of the pair of vibrating arms 21 and 22 for the purpose of further reducing the equivalent series resistance value (hereinafter abbreviated as CI value). Specifically, the long groove G1 and the long groove G3 are formed on the front and back main surfaces of the vibrating arm 21 so as to face each other, and the long groove G2 and the long groove G4 face each other on the front and back main surfaces of the vibrating arm 22. It is formed like this. The long grooves G1 to G4 are formed on the front and back main surfaces of each of the pair of vibrating arms 21 and 22 at a predetermined depth, one end side thereof is extended to the region of one end side 201 of the base 20, and the other end side is the vibrating arm. It is formed up to the base side of the vibrating arm with respect to the boundary between the and the widened portion. The long grooves G1 to G4 have a longitudinal direction along a first direction in which the vibrating arms 21 and 22 extend, and a lateral direction along a second direction in which the vibrating arms 21 and 22 are parallel to each other. The region of the vibrating arm in which the long grooves G1 to G4 exist constitutes the vibrating portion.

The outer shape of the crystal vibrating piece 2 described above is formed from one crystal wafer in large numbers at the same time by using photolithography technology and wet etching.

The crystal vibrating piece 2 includes a first excitation electrode 25 and a second excitation electrode 26 composed of different potentials, and an electrode drawn from each of the first excitation electrode 25 and the second excitation electrode 26 (described later). The lead-out electrodes 27 and 28 drawn out via the above are formed.

A part of the first and second excitation electrodes 25 and 26 formed on the front and back main surfaces of the pair of vibrating arms 21 and 22 extends over the entire inside of the long grooves G1 to G4 of the pair of vibrating arms 21 and 22. It is formed. By forming the long groove, the electric field efficiency of the pair of vibrating arms 21 and 22 is increased even if the crystal vibrating piece is miniaturized, and a good CI value can be obtained. In addition, only the first and second excitation electrodes may be formed only in a part of the inside of the long grooves G1 to G4 of the pair of vibrating arms.

The first excitation electrode 25 is formed on the front and back main surfaces of one vibrating arm 21 and on the outer surface and inner surface of the other vibrating arm 22 via a routing electrode (reference numeral omitted). Similarly, the second excitation electrode 26 is formed on the front and back main surfaces of the other vibrating arm 22 and on the outer surface and the inner surface of the one vibrating arm 21 via the routing electrode (reference numeral omitted). ..

One of the extraction electrodes 27 formed on the base portion via the first excitation electrode 25 formed on each of the outer surface and the inner surface of the other vibrating arm 22 and the routing electrode (reference numeral omitted). A first excitation electrode 25 formed on the front and back main surfaces of the vibrating arm 21 is connected. Similarly, the extraction electrode 28 formed on the base 20 passes through the second excitation electrode 26 formed on each of the outer surface and the inner surface of one of the vibrating arms 21 and the routing electrode (reference numeral omitted). , A second excitation electrode 26 formed on the front and back main surfaces of the other vibrating arm 22 is connected.

The extraction electrodes 27 and 28 are drawn out from one end side 201 of the base portion 20 to the narrowed width portion 204 on the surface 2a of the crystal vibrating piece 2 as shown in FIG. On the other hand, on the back surface 2b of the crystal vibrating piece 2, the extraction electrodes 27 and 28 are drawn out from one end side 201 of the base portion 20 to the other end side 202 and the tip end side of the protruding portion 24 as shown in FIG. Then, each region of the base end portion 241 of the base portion 20 and the tip end portion 242 of the protruding portion 24 on the back surface 2b of the crystal vibrating piece 2 is electromechanically connected to the mounting pads 6a and 6b of the container 3, respectively. , 271.

The above-mentioned routing electrodes are formed on all the surfaces of the pair of main surfaces and the pair of side surfaces constituting the wide portions 23, 23, respectively. In the present embodiment, the routing electrodes are formed on the entire circumference of the wide portion 23 (a pair of main surfaces and a pair of side surfaces) and the entire circumference of the portion of the vibrating arms 21 and 22 near the widened portion.

In the above-mentioned first and second excitation electrodes 25 and 26, the extraction electrodes 27 and 28, and the routing electrode (reference numeral omitted), a chromium (Cr) layer is formed on the quartz substrate, and gold is formed on the chromium layer. It has a layer structure in which (Au) layers are laminated. These metal films are formed on the entire main surface of the crystal wafer by a vacuum vapor deposition method, sputtering, or the like, and then are simultaneously formed into a desired pattern by photolithography technology and metal etching. The layer structure of the various electrodes is not limited to the layer structure in which the gold layer is formed on the chromium layer, and may be another layer structure.

In the embodiment of the present invention, the frequency adjusting metal film W (frequency adjusting weight) is formed on only one main surface (surface 2a) of the surfaces constituting the wide portion 23 (see FIG. 3). The oscillation frequency of the crystal vibration piece 2 is finely adjusted by reducing the mass of the frequency adjusting metal film W by irradiating a beam such as a laser beam or an ion beam.

As shown in FIG. 4, a first metal bump 7a is provided on the other end side 202 of the base portion 20 and on the central side in the second direction. Specifically, the first metal bump 7a is the upper surface of the connection electrode 271, passes through the center in the width direction (second direction) of the base 20, and follows the extension direction (first direction) of the pair of vibrating arms. It is formed at a position close to the virtual center line CL. The first metal bump may be provided on the virtual center line CL. On the other hand, a second metal bump 7b is provided on the tip end side of the protruding portion 24 so as to be separated from the first metal bump 7a.

In the present embodiment, the first metal bump 7a and the second metal bump 7b are plating bumps formed by the electrolytic plating method. The conductive bonding between the crystal vibrating piece 2 and the mounting pads 6a and 6b is performed by the FCB method (Flip Chip Bonding).

The first metal bump 7a and the second metal bump 7b have the same shape in a plan view. Specifically, the first and second metal bumps 7a and 7b have an isosceles right triangle shape in a plan view. Here, the first metal bump 7a and the second metal bump 7b are formed so that the base 7a2 and the base 7b2 of the isosceles right triangle face each other. That is, as the first metal bump 7a and the second metal bump 7b are separated from the opposite sides (bottom sides 7a2, 7b2) on both outer sides (-X-axis direction, + X-axis direction) in the second direction, the area in the plan view becomes larger. is decreasing.

In the present embodiment, the first metal bump 7a has a larger area in a plan view than the second metal bump 7b. Specifically, the area of the first metal bump 7a in a plan view is formed so as to be twice or more and three times or less the area of the second metal bump 7b in a plan view. The first metal bump 7a and the second metal bump 7b may be formed in the same area in a plan view. Further, in the present embodiment, the plan-view shapes of the first metal bump and the second metal bump are isosceles triangles, but they may be equilateral triangles or right triangles.

According to the embodiment of the present invention, since the first metal bump 7a and the second metal bump 7b have the same shape, the stress acting on the joint portion between the crystal vibrating piece 2 and the bumps 7a and 7b is maintained. be able to. Further, since the area of the first metal bump 7a and the second metal bump 7b decreases in the plan view as they are separated from the opposite sides (bottom sides 7a2, 7b2) to both outer sides in the second direction, the first metal bump 7a And inside the second metal bump 7b, the opposite sides are joined more strongly. As a result, deformation of the other end side 202 of the base portion 20 (contraction toward the center side in the width direction of the base portion 20) due to expansion of the container 3 is suppressed, so that the tip side (wide portion) of the pair of vibrating arms 21 and 22 is suppressed. The force that 23, 23) tries to open outward is weakened. As a result, the pseudo stretching of the vibrating arm is suppressed, so that the decrease in the oscillation frequency can be suppressed.

Further, according to the embodiment of the present invention, since the first metal bump 7a has a larger area in a plan view than the second metal bump 7b, the central side in the width direction (second direction) of the base 20 is relatively strong. Be joined. As a result, deformation of the other end side 202 of the base portion 20 (contraction toward the center side in the width direction of the base portion 20) due to expansion of the container 2 is suppressed, so that the tip side of the pair of vibrating arms 21 and 22 opens outward. The power to try is weakened. As a result, the pseudo stretching of the vibrating arm is suppressed, so that the decrease in the oscillation frequency can be further suppressed.

Further, according to the embodiment of the present invention, the first metal bump 7a and the second metal bump 7b are formed into an isosceles triangle in a plan view, and the bases 7a2, 7b2 of the triangle face each other, so that they face each other. The areas of the first metal bump 7a and the second metal bump 7b in a plan view continuously decrease as they are separated from the sides (bases 7a2, 7b2) on both outer sides (-X-axis direction, + X-axis direction) in the second direction. do. As a result, the stress acting on each joint between the crystal vibrating piece 2 and the bumps 7a and 7b can be continuously changed. As a result, it is possible to further suppress a decrease in the oscillation frequency of the crystal oscillator 1.

In the embodiment of the present invention, the shape of the first metal bump and the second metal bump in the plan view is an isosceles triangle, but as another application example of the present invention, the plan view of the first metal bump and the second metal bump is taken. The shape of the above may be the shape shown in FIGS. 5 to 6. 5 to 6 and 7 to 11 described later are plan views of the crystal vibrating piece with the base and the protruding portion enlarged from the other main surface side (back surface side), and the tuning fork type crystal vibrating piece 2 Since the direction of the crystal axis of the above and the various electrodes formed on the tuning fork type crystal vibrating piece 2 are the same as those in FIG. 4, their display is omitted. Further, the same configuration as that of the above-described embodiment of the present invention will be indicated by using the same reference numerals, and the description thereof will be omitted.

In the application example shown in FIG. 5, the shapes of the first metal bump 10a and the second metal bump 10b in a plan view are semi-elliptical. On the other hand, in the application example shown in FIG. 6, the shapes of the first metal bump 11a and the second metal bump 11b in a plan view are trapezoidal.

Even with these shapes, in the plan view of the first metal bump and the second metal bump as they are separated from the opposite sides of each metal bump toward both outer sides (-X-axis direction and + X-axis direction) in the second direction. The area is decreasing continuously. As a result, the stress acting on each joint of the crystal vibrating piece 2, the first metal bump, and the second metal bump can be continuously changed. As a result, it is possible to suppress a decrease in the oscillation frequency of the crystal oscillator.

Further, as another application example of the present invention, the shapes of the first metal bump and the second metal bump in a plan view may be as shown in FIGS. 7 to 11. The areas of the first metal bumps (12a, 13a, 14a, 15a, 16a) and the second metal bumps (12b, 13b, 14b, 15b, 16b) in FIGS. ing.

Even with these shapes, in the plan view of the first metal bump and the second metal bump as they are separated from the opposite sides of each metal bump toward both outer sides (-X-axis direction and + X-axis direction) in the second direction. The area decreases discontinuously. As a result, the stress acting on each joint of the crystal vibrating piece 2, the first metal bump, and the second metal bump can be changed stepwise. As a result, it is possible to suppress a decrease in the oscillation frequency of the crystal oscillator 1.

The tuning fork type crystal vibrating piece according to the embodiment of the present invention and other application examples described above has a configuration in which a through hole is not formed at the base. In the present invention, not only the piezoelectric vibrating piece having such a configuration, but also the through holes H at each of the positions which are closer to one end side of the base 190 and are line-symmetric with respect to the virtual center line CL as shown in FIG. It is also applicable to a piezoelectric vibrating piece having a structure in which (through hole) is formed.

FIG. 12 is a plan view of the tuning fork type crystal vibrating piece 19 (hereinafter, abbreviated as crystal vibrating piece 19) in which the base 190 and the protruding portion 193 are enlarged, as viewed from the other main surface side (back surface side). Since the direction of the crystal axis of the piece 19 and the various electrodes formed on the crystal vibrating piece 19 are the same as those in FIG. 4, their display is omitted. Further, the same configuration as that of the above-described embodiment of the present invention will be indicated by using the same reference numerals, and the description thereof will be omitted. Further, also in FIG. 12, since the various electrodes formed on the crystal vibrating piece 19 are the same as those in FIG. 4, the display thereof is omitted.

A metal film (not shown) is adhered to the inner wall surface of the through hole H, and an electrical connection is made between the front and back extraction electrodes of the base 190 via the metal film. In the case of a tuning fork type crystal vibrating piece having a pair of through holes formed in the base, the rigidity of the base is lower than that of the tuning fork type crystal vibrating piece having no through hole formed. Deformation on the end side (contraction toward the center in the width direction of the base) is relatively likely to occur. Therefore, the force that the tip side of the pair of vibrating arms tries to open outward becomes large.

On the other hand, according to the configuration of the present invention shown in FIG. 12, the first metal bump 7a and the second metal bump 7b suppress the deformation of the other end side 192 of the base 190 due to the expansion of the container, so that a pair. The force that the tip side of the vibrating arm tries to open outward is weakened. As a result, the pseudo stretching of the vibrating arm is suppressed, so that the decrease in the oscillation frequency can be suppressed. The present invention is also suitable for a small tuning fork type piezoelectric vibrating piece having a through hole formed in the base as shown in FIG.

The shapes of the first metal bump and the second metal bump according to the present invention in a plan view are not limited to the shapes shown in FIGS. 4 to 12. That is, if the first metal bump and the second metal bump have the same shape in the plan view and the area in the plan view decreases as they are separated from the opposite sides to both outer sides in the second direction, the above-described description will be made. The shape may be other than the embodiment of the present invention and other application examples.

In the embodiment of the present invention, a sound-forked crystal oscillator in which only the sound-forked crystal vibrating piece is mounted in a container is given as an example. The present invention is applicable even if the element (IC) is a piezoelectric oscillator housed in a container.

The present invention can be practiced in various other ways without departing from its spirit or key features. Therefore, the above embodiments are merely exemplary in all respects and should not be construed in a limited way. The scope of the present invention is shown by the scope of claims, and is not bound by the text of the specification. Furthermore, all modifications and modifications that fall within the equivalent scope of the claims are within the scope of the present invention.

It can be applied to mass production of piezoelectric devices.

1 Tuning fork crystal oscillator 2, 19 Tuning fork crystal oscillator 20, 190 Base 21, 22, Vibrating arm 24, 193 Protruding part 3 Container 6a, 6b Mounting pad 7a, 10a, 11a, 12a, 13a, 14a, 15a, 16a 1st metal bump 7b, 10b, 11b, 12b, 13b, 14b, 15b, 16b 2nd metal bump

Claims (3)

A tuning fork type piezoelectric vibrating piece is a piezoelectric device in which two mounting pads provided on a container are conductively bonded via metal bumps.
The tuning fork type piezoelectric vibrating piece has a base portion, a pair of vibrating arms extending from one end side of the base portion in the first direction, and a protrusion extending from the other end side of the base portion in one of the second directions orthogonal to the first direction. With a part
The tuning fork type piezoelectric vibrating piece includes a first metal bump provided on the other end side of the base portion and on the central side in the second direction, and a second metal bump provided on the tip end side of the protruding portion. It is joined to the two mounting pads via
The first metal bump and the second metal bump are formed in the same shape in a plan view and have opposite sides, and the area in the plan view decreases as the distance from the facing side to both outer sides in the second direction decreases. A piezoelectric device characterized by being The piezoelectric device according to claim 1, wherein the first metal bump has a larger area in a plan view than the second metal bump. The piezoelectric device according to claim 1 or 2, wherein the first metal bump and the second metal bump are formed in a substantially triangular shape in a plan view, and the bases of the triangles face each other.

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