Tuning fork type piezoelectric vibration device

Abstract

This invention provides a tuning fork-type piezoelectric vibrator device that prevents mounting misalignment of the tuning fork-type piezoelectric vibrator, enabling more stable manufacturing. [Solution] The first mounting pad 6a and the second mounting pad 6b, provided on the upper surface of the stepped portion 32 of the package 3, are formed in an upward-convex shape having a curved surface such that their thickness decreases (gradually decreases) as they approach each other in the second direction (X direction), and the joining members 7a and 7b of the tuning fork type piezoelectric vibrator 2 are connected to the curved portions of the upward-convex mounting pads 6a and 6b, forming a tuning fork type piezoelectric oscillator 1.

Description

Technical Field

[0001] The present invention relates to a tuning fork type piezoelectric vibration device equipped with a tuning fork type piezoelectric vibration piece in which a pair of vibrating arms vibrate in a bending vibration mode.

Background Art

[0002] Among piezoelectric vibration devices, tuning fork type piezoelectric vibration devices equipped with tuning fork type piezoelectric vibration pieces have been widely used as frequency generation sources for reference signals in timepieces and the like.

[0003] As such a tuning fork type piezoelectric vibration piece, a tuning fork type piezoelectric vibration piece having a holding portion that is substantially L-shaped in plan view is disclosed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in a tuning fork type piezoelectric vibration device equipped with a tuning fork type piezoelectric vibration piece having a holding portion that is substantially L-shaped in plan view as described in Patent Document 1, there is a risk of mounting misalignment, especially when mounting the tuning fork type piezoelectric vibration piece on a package by performing bump bonding using metal bumps. That is, a tuning fork type piezoelectric vibration device capable of more stable manufacturing has been desired.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a tuning fork type piezoelectric vibration device that prevents mounting misalignment of the tuning fork type piezoelectric vibration piece and enables more stable manufacturing.

Means for Solving the Problems

[0007] The present invention relates to a tuning fork type piezoelectric vibration device comprising a tuning fork type piezoelectric vibrator and a package that houses the tuning fork type piezoelectric vibrator in an internal housing, wherein the tuning fork type piezoelectric vibrator comprises a base, a pair of vibrating arms extending in a first direction from one end of the base, and a holding portion extending from the other end of the base in the opposite direction to the extension direction of the vibrating arms and protruding in at least one of a second direction perpendicular to the first direction, the holding portion having joints that are joined to the package via a joining member at a plurality of positions spaced apart in the second direction, the package having two vibrator mounting pads that are joined to the tuning fork type piezoelectric vibrator and a stepped portion having the two vibrator mounting pads on its upper surface in the housing, the two vibrator mounting pads having an upward convex shape with a curved surface whose thickness gradually decreases as they approach each other in the short-side direction of the housing, and the joints are arranged on adjacent curved surfaces of the vibrator mounting pads, making it a tuning fork type piezoelectric vibration device.

[0008] In other words, the tuning fork type piezoelectric vibration device of the present invention has a housing portion comprising two vibration piece mounting pads, each joined to a tuning fork type piezoelectric vibrator, and a stepped portion having the two vibration piece mounting pads on its upper surface. The two vibration piece mounting pads have an upward convex shape with curved surfaces whose thickness gradually decreases as they approach each other in the short-side direction of the housing portion, and the joining portion is arranged on adjacent curved surfaces of the vibration piece mounting pads. This configuration makes it possible to prevent mounting misalignment of the tuning fork type piezoelectric vibrator. That is, since the joining members of the tuning fork type piezoelectric vibrator are joined to two opposing curved surfaces when mounted, slippage in the short-side direction of the housing portion is less likely to occur, and misalignment of the mounting position can be prevented.

[0009] Furthermore, in the present invention, the two vibrating element mounting pads have an upward-convex shape with curved surfaces whose thickness gradually decreases as they approach each other in the short-side direction of the housing, and the joints are located on adjacent curved surfaces of the vibrating element mounting pads, thereby reducing the distance between the two joints. In this case, one joint member is positioned closer to the protruding direction in which the other joint member is provided in the holding portion, thereby preventing acoustic leakage. In other words, the electrical characteristics of the piezoelectric vibration device can be improved.

[0010] Furthermore, the tuning fork-type piezoelectric vibrator may have two metal wiring patterns that are opposite in polarity, and the vibrator mounting pad may be configured to superimpose only one of the two opposite-polarity metal wiring patterns in a region where its thickness is greater than the location of the joint. With such a configuration, it is possible to prevent the vibrator mounting pad from coming into contact with the opposite-polarity metal wiring patterns provided on the holding part and causing a short circuit.

[0011] Furthermore, the base of the tuning fork-type piezoelectric vibrator and the vibrator mounting pad on the package may not overlap in a plan view. In such a configuration, even if the tuning fork-type piezoelectric vibrator, which is cantilevered to the package, tilts in the thickness direction with the joint as a fulcrum, the base and the vibrator mounting pad will not come into contact, and the vibrator mounting pad, which is provided on the stepped portion to electrically connect the opposite-polarity metal wiring patterns provided on the base, will not come into contact. In other words, the reliability of the tuning fork-type piezoelectric vibration device can be improved.

[0012] Furthermore, the joining member may be formed by bumps made of metal. With such a configuration, the bonding strength can be significantly higher compared to when a conductive adhesive is used. [Effects of the Invention]

[0013] According to the present invention, it is possible to prevent misalignment of the tuning fork-type piezoelectric vibrator and provide a tuning fork-type piezoelectric vibrator that enables more stable manufacturing. [Brief explanation of the drawing]

[0014] [Figure 1] A top view of the tuning fork type piezoelectric oscillator according to the first embodiment, with the cover removed. [Figure 2] A schematic internal side view of a tuning fork type piezoelectric oscillator according to the first embodiment. [Figure 3] A top view of a tuning fork-type piezoelectric vibrator according to the first embodiment. [Figure 4] Enlarged view of the base and retaining area in Figure 1. [Figure 5] Cross-sectional view AA in Figure 4. [Figure 6] Enlarged view of the base and retaining area in the conventional technology. [Modes for carrying out the invention]

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification, the tuning fork type piezoelectric vibration device is described as a tuning fork type piezoelectric oscillator having a tuning fork type piezoelectric vibrator and an IC. Furthermore, the X-axis direction (X direction) described in each drawing and this specification is the same direction as the X-axis direction of the quartz crystal axis, the Y-axis direction (Y direction) is the same direction as the Y-axis direction of the quartz crystal axis (or the Y' direction tilted a few degrees from the Y axis), and the Z-axis direction (Z direction) is the same direction as the Z-axis direction of the quartz crystal axis (or the Z' direction tilted a few degrees from the Z axis).

[0016] <First Embodiment> Figure 1 is a top view of the tuning fork type piezoelectric oscillator 1 according to the first embodiment with the cover 4 removed; Figure 2 is a schematic internal side view of the tuning fork type piezoelectric oscillator 1; Figure 3 is a top view of the tuning fork type piezoelectric vibrating piece 2 according to the first embodiment; Figure 4 is an enlarged view of the base and holding part area in Figure 1; and Figure 5 is a cross-sectional view of AA in Figure 4. In this specification, the depth direction in FIG. 1 is defined as the bottom surface side of the tuning fork type piezoelectric oscillator 1, and the front direction is defined as the upper surface side of the tuning fork type piezoelectric oscillator 1. The bottom surface and the upper surface are described accordingly. Also, in FIGS. 4 and 5, the package 3 is omitted.

[0017] The tuning fork type piezoelectric oscillator 1 (hereinafter referred to as the piezoelectric oscillator 1) in this embodiment includes a package 3 having a substantially rectangular housing portion 31 with the Y direction as the long side direction, a tuning fork type piezoelectric vibrating piece 2 and an IC 5 housed in the housing portion 31, and a lid 4 joined to the upper surface of the package 3 to hermetically seal the housing portion 31. That is, in the piezoelectric oscillator 1, the tuning fork type piezoelectric vibrating piece 2 and the IC 5 are housed in the same space (housing portion 31). In this embodiment, the longitudinal direction (first direction) of the tuning fork type piezoelectric vibrating piece 2 is arranged to be substantially parallel to the long side direction of the housing portion 31. That is, the longitudinal direction of the tuning fork type piezoelectric vibrating piece 2 is the Y direction, and the long side direction of the housing portion 31 is the first direction.

[0018] The package 3 is a box-shaped body made of an insulating material mainly composed of ceramics such as alumina. For example, it is formed by a lower layer portion 3a, a middle layer portion 3b, and an upper layer portion 3c which are formed by laminating three ceramic green sheets and integrally firing them. In this embodiment, among the lower layer portion 3a, the middle layer portion 3b, and the upper layer portion 3c, the middle layer portion 3b in a rectangular frame shape is laminated on the lower layer portion 3a arranged at the bottom most, and the upper layer portion 3c in a rectangular frame shape is further laminated on the middle layer portion 3b. Therefore, the package 3 has a rectangular housing portion 31 in a plan view with the upper surface of the lower layer portion 3a as the bottom surface and the middle layer portion 3b and the upper layer portion 3c as the frame-shaped dike portions 30. Also, the middle layer portion 3b protrudes toward the housing portion 31, and a part of it constitutes a stepped portion 32 on which the tuning fork type piezoelectric vibrating piece 2 is mounted.

[0019] In addition, the package 3 has external terminals 8 made of a metal film on the outer bottom surface (the main surface on the side where the embankment portion 30 of the lower layer portion 3a is not provided). In the present embodiment, four external terminals 8 are provided at each corner on the bottom surface of the package 3 having a substantially rectangular shape, that is, in addition to the two external terminals 8 shown in the figure, two external terminals not shown are provided. Note that the number of external terminals 8 provided on the outer bottom surface of the package 3 is not particularly limited and can be an appropriate number depending on the size of the package 3, the number of terminals of the external substrate on which the piezoelectric oscillator 1 is mounted, or the use of the piezoelectric oscillator 1 or the like.

[0020] Furthermore, the package 3 has IC mounting pads 34 for mounting the IC 5 on the bottom surface of the accommodating portion 31 (the upper surface of the lower layer portion 3a). The IC mounting pads 34 are conductively joined to corresponding external mounting terminals (not shown) provided on the IC 5 via a joining material 51. Therefore, the package 3 has an IC accommodating portion 31a formed by the bottom surface (the upper surface of the lower layer portion 3a) and the inner surface of the middle layer portion 3b as a part of the accommodating portion 31. The IC mounting pads 34 can be formed, for example, by laminating nickel and gold in this order on the upper surface of a tungsten metallized layer using a technique such as plating. Note that molybdenum may be used instead of tungsten as the metallized layer. The joining material 51 can be, for example, a gold metal bump. In such a case, the IC 5 can be mounted on the package 3 by bump bonding. Note that the number of IC mounting pads 34 provided on the bottom surface of the accommodating portion 31 is not particularly limited and can be an appropriate number depending on the number of external mounting terminals of the IC 5 to be mounted.

[0021] Note that in the present embodiment, the package 3 is formed of ceramic, but the present invention is not limited to this configuration. For example, the package 3 may be formed of quartz or glass.

[0022] Furthermore, the width L1 of the stepped portion 32 in the Y direction (first direction) is formed to be 15% or less of the width L2 of the housing portion 31 in the Y direction (first direction). In addition, it is preferable that the width L1 of the stepped portion 32 in the Y direction (first direction) is greater than or equal to the width of the holding portion 23 of the tuning fork type piezoelectric vibrator 2, which will be described later, in the Y direction.

[0023] Furthermore, the stepped portion 32 includes a first mounting pad 6a and a second mounting pad 6b, which are electrically bonded to a tuning fork-shaped piezoelectric vibrating piece 2 on their upper surfaces. The first mounting pad 6a and the second mounting pad 6b are formed in parallel with a gap between them. The first mounting pad 6a and the second mounting pad 6b have an upward-convex shape, with the apex near the center in a plan view, and the thickness gradually decreasing towards the periphery. Therefore, the first mounting pad 6a and the second mounting pad 6b are formed in an upward-convex shape with a curved surface such that their thickness decreases as they approach each other in the short-side direction (second direction) of the housing portion 31. The first mounting pad 6a and the second mounting pad 6b are opposite poles to each other and are electrically connected to a plurality of external terminals 8 provided on the outer bottom surface of the package 3 via internal wiring and vias (not shown). In this embodiment, the first mounting pad 6a and the second mounting pad 6b are formed to the full edge 32a of the stepped portion 32 in the Y direction (second direction).

[0024] In this embodiment, the first mounted pad 6a, the second mounted pad 6b, and each external terminal can be formed, for example, by laminating nickel and gold in that order on the upper surface of the tungsten metallized layer using a method such as plating. Molybdenum may be used instead of tungsten as the metallized layer.

[0025] The lid 4 can be, for example, a rectangular metal lid in plan view, with Kovar as the base material. Alternatively, the lid 4 can have a configuration in which a metal brazing material is formed around the periphery on the nickel-plated outer periphery of the surface that joins with the package 3. Furthermore, the lid 4 and the package 3 can be joined by brazing or seam welding.

[0026] The tuning fork-type piezoelectric vibrator 2 is a thin, plate-shaped quartz Z-plate with thickness in the Z direction. The tuning fork-type piezoelectric vibrator 2 comprises a base portion 20, a pair of vibrating arms 21 and 22 formed side-by-side and projecting (extending) in the +Y direction (first direction) from one end of the base portion 20, and a holding portion 23 formed in the -Y direction from the other end of the base portion 20. The holding portion 23 extends a predetermined length in the first direction from the base portion 20 and then bends in a second direction (+X direction) perpendicular to the first direction. Therefore, the tuning fork-type piezoelectric vibrator 2 has a tuning fork shape in plan view, and the holding portion 23 is formed in a substantially L-shape in plan view. In this embodiment, the base portion 20 is the range from the boundary where the vibrating arms 21 and 22 rise up to the boundary where the holding portion 23 rises up. In this embodiment, the vibrating arms 21 and 22 are formed extending in the +Y direction, but they may also be formed extending in the -Y direction. Furthermore, in this embodiment, the holding portion 23 is formed bent in the +X direction, but it may also be formed bent in the -X direction.

[0027] The shape of the tuning fork-type piezoelectric vibrator 2 in this embodiment (the vibrating arms 21, 22, the base 20, and the holding part 23 that constitute the tuning fork-type piezoelectric vibrator 2) is formed, for example, by wet etching from a quartz plate, which is a quartz crystal made of an anisotropic material.

[0028] Furthermore, the tuning fork-type piezoelectric vibrator 2 has a first excitation electrode and a second excitation electrode, which are configured at different potentials, and lead electrodes drawn out from each of the first and second excitation electrodes via lead electrodes. The first excitation electrode is formed on the front and back main surfaces of one vibrating arm 21 and on the outer and inner surfaces of the other vibrating arm 22 via the lead electrodes. Similarly, the second excitation electrode is formed on the front and back main surfaces of the other vibrating arm 22 and on the outer and inner surfaces of one vibrating arm 21 via the lead electrodes. The lead electrodes drawn out from the first excitation electrode are connected to the joining member 7b, and the lead electrodes drawn out from the second excitation electrode are connected to the joining member 7a. Note that the illustration of each electrode pattern is omitted in Figures 1, 2, and 3.

[0029] In this embodiment, the base portion 20 has a symmetrical shape in plan view (symmetrical in the X direction). Furthermore, the base portion 20 is wider (longer in the X direction) than the vibrating arm portions 21, 22 and the holding portion 23. The base portion 20 is also formed to gradually narrow from the vibrating arm portion 21, 22 side to the holding portion 23 side. In addition, the base portion 20 has two through holes 20a and 20b that penetrate in the Z direction. In this embodiment, the two through holes 20a and 20b are arranged side by side in the X direction. Furthermore, opposite polarity lead electrodes (metal wiring patterns) are formed on the inner wall surfaces of the two through holes 20a and 20b, and the lead electrodes on the front and back sides are routed so that they are connected on their inner wall surfaces. With such a configuration of through holes, electrical conductivity of the lead electrodes can be ensured. Furthermore, by efficiently damping the mechanical vibrations of the tuning fork vibrating arm during operation and suppressing the propagation of vibrations to the connecting members 7a and 7b, acoustic leakage can be reduced and the series resonance resistance (CI) can be lowered.

[0030] Each pair of vibrating arms 21 and 22 has a vibrating section 211 and 221 extending from the base 20, and a wide section 212 and 222 (weight section) provided at the tip of each arm, which is wider than the width of the vibrating section 211 and 221.

[0031] The wide sections 212 and 222 are formed continuously from the tip portions of the vibrating sections 211 and 221 via widening sections 213 and 223 that gradually widen in the width direction (X direction). The corners on the tip side of each of the wide sections 212 and 222 are processed to be chamfer.

[0032] Furthermore, long grooves 214 and 224 are formed on the front and back main surfaces of each of the pair of vibrating arms 21 and 22, respectively, for the purpose of further reducing the equivalent series resistance value (Crystal Impedance, CI value). More specifically, the vibrating arm 21 has a long groove 214 formed on its front main surface (front surface) and a long groove (not shown) formed on its back main surface (back surface). The long grooves formed on the front and back surfaces are arranged to face each other in the thickness direction. Similarly, the vibrating arm 22 has a long groove 224 formed on its front main surface (front surface) and a long groove (not shown) formed on its back main surface (back surface). The long grooves formed on the front and back surfaces are arranged to face each other in the thickness direction. The long grooves 214 and 224 formed on the front surfaces of the vibrating arms 21 and 22, and the long groove (not shown) formed on the back surface, are formed on the front and back main surfaces of the vibrating arms 21 and 22 with a predetermined depth (length in the Z direction) and width (length in the X direction). Furthermore, each elongated groove is formed with one end in the Y direction extending to one end of the base 20, and the other end near the boundary between the vibrating sections 211, 221 and the widening sections 213, 223. In other words, all elongated grooves have a longitudinal direction along the direction in which the vibrating arms 21, 22 protrude (Y direction) and a width direction along the direction in which the vibrating arms 21, 22 are arranged side by side (X direction). Such elongated grooves can be formed, for example, by wet etching when forming the outer shape of the tuning fork-type piezoelectric vibrating piece 2.

[0033] In this embodiment, the retaining portion 23 is formed to protrude in the -Y direction from the other end of the base portion 20. That is, the retaining portion 23 is formed to protrude in a first direction from the other end of the base portion 20. Furthermore, the retaining portion 23 is formed by bending in the +X direction after protruding a predetermined distance from the base portion 20. Therefore, the retaining portion 23 has a substantially L-shape in plan view.

[0034] In this embodiment, the holding portion 23 has a connecting member 7b at the tip portion bent in the X direction (the tip portion in the +X direction), and a connecting member 7a on the -X side from the center in the X direction. The connecting member 7a in this embodiment is provided near the center of the holding portion 23 in the X direction, and is provided near the bent portion of the holding portion 23 that protrudes in the +X direction. Furthermore, the connecting member 7a in this embodiment is provided in the +X direction (the direction in which the holding portion 23 protrudes) from the central axis of the two vibrating arms 21 and 22 that is parallel to the Y direction. The connecting members 7a and 7b are Au plated bumps formed by electroplating. The position, shape, and number of connecting members 7a and 7b are not particularly limited. That is, although the connecting members 7a and 7b in this embodiment are elliptical in shape of the same size, they can be of various shapes, and the connecting members 7a and 7b may be of different sizes and external shapes. Furthermore, in this embodiment, two joining members 7a and 7b are formed on the holding portion 23, but any configuration in which multiple joining members are electrically connected to two opposite polarity lead electrodes by a conductive material is acceptable, and there may be three or more Au bumps. In addition, in this embodiment, the joining member 7a is provided near the center in the X direction of the holding portion 23, but it may also be provided at the end opposite to the end where the joining member 7b is provided (the end in the -X direction).

[0035] As shown in Figure 1, the tuning fork-type piezoelectric vibrator 2 is joined and held on the upper surface of the stepped portion 32 of the package 3. More specifically, the first mounting pads 6a and 2 mounting pads 6b of the stepped portion 32 are joined to the joining members 7a and 7b of the tuning fork-type piezoelectric vibrator 2, forming joints. In this embodiment, the first mounting pad 6a is connected to the joining member 7a, and the second mounting pad 6b is connected to the joining member 7b. That is, the first mounting pad 6a and the second mounting pad 6b correspond to the vibrator mounting pads in this invention. Furthermore, in the case of a configuration where the holding portion 23 has an L-shape, as in this embodiment, the tuning fork-type piezoelectric vibrator 2 is held in a cantilevered state, with the package 3 being held only on one end of its long side.

[0036] Furthermore, the mounting position of the tuning fork-type piezoelectric vibrator 2 on the mounting pads 6a and 6b is such that the center line Q of the joining members 7a and 7b in the Y direction falls within a range of 15% in the Y direction (+Y direction and -Y direction) from the center line P in the long side direction (Y direction) of the housing portion 31 of the mounting pads 6a and 6b. At this time, as shown in Figure 4, the mounting pads 6a and 6b and the Y-direction edge 32a of the stepped portion 32 and the base portion 20 of the tuning fork-type piezoelectric vibrator 2 are arranged so that they do not overlap in a plan view.

[0037] Furthermore, the joining members 7a and 7b are connected at the curved portions of the mounting pads 6a and 6b, which have an upward-convex shape. In particular, in this embodiment, the joining members 7a and 7b are connected to the curved portions of the mounting pads 6a and 6b, which are spaced apart from each other (see Figure 5). That is, the mounting pads 6a and 6b have an upward-convex curved surface and a thickest part (top), and the tuning fork-type piezoelectric vibrator 2 is positioned in the region of the curved surface that is thinner than the top. Furthermore, in the region where the first mounting pad 6a is thicker than the connection position with the joining member 7a, it superimposes in a plan view only with the lead electrode 2a that is connected to the joining member 7a of the tuning fork-type piezoelectric vibrator 2, and does not superimpose with the lead electrode 2b, which is of the opposite polarity to the lead electrode 2a. Similarly, the second mounted pad 6b, in a region where its thickness is greater than the connection position with the joining member 7b, superimposes in a plan view only with the lead electrode 2b connected to the joining member 7b of the tuning fork-type piezoelectric vibrator 2, and does not superimpose with the lead electrode 2a, which is of the opposite polarity to the lead electrode 2b.

[0038] In this embodiment, the joining members 7a and 7b and the mounting pads 6a and 6b are bump-joined by the FCB (Flip Chip Bonding) method. That is, the Au metal bumps of the joining members 7a and 7b and the Au layer formed on the outermost surface of the mounting pads 6a and 6b are electrically bonded by bump bonding.

[0039] Furthermore, it is preferable that the total length of the tuning fork-type piezoelectric vibrator 2 in the Y direction be 90% or more of the size L2 of the housing 31 in the long side direction (Y direction, first direction). With such a configuration, a small package 3 can be made for a tuning fork-type piezoelectric vibrator 2 that has the required characteristics, and the piezoelectric oscillator 1 can be miniaturized.

[0040] IC5 has a temperature sensor and an oscillation circuit that causes the tuning fork-type piezoelectric vibrator 2 to oscillate. In this embodiment, IC5 is an IC chip having a roughly rectangular parallelepiped shape and has external mounting terminals on its bottom surface that correspond to the IC mounting pad 34. IC5 is electrically connected to the IC mounting pad 34 of package 3 via a bonding material 51.

[0041] The piezoelectric oscillator 1 has a configuration in which the tuning fork-type piezoelectric vibrator 2 and IC 5 are superimposed on each other when the tuning fork-type piezoelectric vibrator 2 and IC 5 are mounted on the package 3. In this configuration, the tuning fork-type piezoelectric vibrator 2 and IC 5 are arranged with a certain gap in the vertical direction (see Figure 2). Furthermore, it is preferable that the vibrating parts 211, 221 and wide parts 212, 222 of the tuning fork-type piezoelectric vibrator 2 are superimposed on IC 5. With such a configuration, the difference between the actual temperature of the vibrating parts 211, 221 and wide parts 212, 222 and the temperature detected by the temperature sensor of IC 5 can be reduced, thereby improving heating drift. Note that contact between the tuning fork-type piezoelectric vibrator 2 and IC 5 is undesirable because it affects the vibration of the tuning fork-type piezoelectric vibrator 2.

[0042] With the above configuration, it is possible to prevent misalignment of the tuning fork-type piezoelectric vibrator and provide a tuning fork-type piezoelectric vibrator that enables more stable manufacturing. In the piezoelectric oscillator 1 of the present invention, the first mounting pad 6a and the second mounting pad 6b provided on the stepped portion 32 are formed in an upward convex shape with a curved surface whose thickness gradually decreases as they approach each other in the short-side direction (second direction) of the housing portion 31, and the joining members 7a and 7b of the tuning fork type piezoelectric vibrator 2 are connected to the curved portions of the upward convex shape of the mounting pads 6a and 6b. With this configuration, when mounting the tuning fork type piezoelectric vibrator 2, it is possible to prevent the tuning fork type piezoelectric vibrator 2 from shifting in the short-side direction (X direction) of the housing portion 31. That is, since the joining members 7a and 7b of the tuning fork type piezoelectric vibrator 2 are joined to the two opposing curved surfaces of the first mounting pad 6a and the second mounting pad 6b, respectively, when mounted, slippage in the short-side direction (X direction) of the housing portion 31 is less likely to occur, and the mounting position can be prevented from shifting.

[0043] Furthermore, by arranging these two joining members 7a and 7b (joints) on opposing curved surfaces of the mounting pads 6a and 6b, the distance between the two joining members 7a and 7b (joints) can be reduced. In this case, the joining member 7a will be closer to the direction in which the holding portion 23 protrudes (the tip where the joining member 7b is provided), thereby preventing acoustic leakage. In other words, the electrical characteristics of the piezoelectric oscillator 1 can be improved.

[0044] Furthermore, the first mounting pad 6a is configured such that, in a region where its thickness is greater than the connection position with the joining member 7a, it superimposes, in a plan view, only the first lead electrode 2a connected to the joining member 7a of the tuning fork-type piezoelectric vibrator 2, and does not superimpose with the second lead electrode 2b, which is of the opposite polarity to the first lead electrode 2a. Similarly, the second mounting pad 6b is configured such that, in a region where its thickness is greater than the connection position with the joining member 7b, it superimposes, in a plan view, only the second lead electrode 2b connected to the joining member 7b of the tuning fork-type piezoelectric vibrator 2, and does not superimpose with the first lead electrode 2a, which is of the opposite polarity to the second lead electrode 2b. In this embodiment, when the joining members 7a and 7b are arranged on a curved surface in mounting pads 6a and 6b having an upward-convex shape, the mounting pads 6a and 6b and the holding portion 23 are more likely to come into contact in a region where its thickness is greater than the connection position with the joining members 7a and 7b. However, with the configuration of the present invention, even if the mounted pads 6a and 6b come into contact with the holding portion 23, it is possible to prevent the mounted pads 6a and 6b from coming into contact in a way that electrically connects the first lead electrode 2a and the second lead electrode 2b, which are of opposite polarity and provided on the holding portion 23, respectively. In other words, it is possible to prevent the mounted pads 6a and 6b from coming into contact with the first lead electrode 2a and the second lead electrode 2b, which are of opposite polarity and provided on the holding portion 23, and causing a short circuit.

[0045] Furthermore, the piezoelectric oscillator 1 of the present invention has a configuration in which the base 20 of the tuning fork-type piezoelectric vibrator 2 and the mounting pads 6a and 6b of the package 3 do not overlap in a plan view. With this configuration, even if the tuning fork-type piezoelectric vibrator 2 is tilted in the thickness direction (-Z direction) with the joining members 7a and 7b (joints) as fulcrums, the base 20 and the mounting pads 6a and 6b do not come into contact. In other words, the first mounting pad 6a provided on the stepped portion 32 does not come into contact with the first and second extraction electrodes 2a and 2b, which are of opposite polarity and provided on the base 20, thereby improving the reliability of the piezoelectric oscillator 1.

[0046] Furthermore, the tuning fork-type piezoelectric vibrator 2 of the present invention is mounted to the package 3 by bump bonding using metal bumps. This configuration allows the tuning fork-type piezoelectric vibrator 2 to be bonded more firmly to the package 3 than when bonded with conductive adhesive. On the other hand, compared to the case where the tuning fork-type piezoelectric vibrator 2 is mounted to the package 3 with conductive adhesive, the thickness of the bonded portion is smaller, and the distance between the tuning fork-type piezoelectric vibrator 2 and the stepped portion 32 and mounting pads 6a, 6b in the thickness direction (Z direction) becomes shorter. In other words, the base portion 20 and holding portion 23 of the tuning fork-type piezoelectric vibrator 2 and the mounting pads 6a, 6b are more likely to come into contact. However, with the configuration of the present invention, the base portion 20 and the stepped portion 32 of the tuning fork-type piezoelectric vibrator 2 do not overlap in a plan view, so it is possible to prevent the mounting pads 6a, 6b provided on the stepped portion 32 from coming into contact with the base portion 20 of the tuning fork-type piezoelectric vibrator 2. Furthermore, even if the mounted pads 6a and 6b come into contact with the holding portion 23, it is possible to prevent the mounted pads 6a and 6b from making contact in a way that electrically connects the first lead electrode 2a and the second lead electrode 2b, which are provided on the holding portion 23 and are of opposite polarity.

[0047] Furthermore, in bump bonding, a large physical pressure is applied in the direction of bonding during bonding, which makes it easy for the mounting position of the tuning fork-type piezoelectric vibrator 2 to shift along the curved surfaces of the mounting pads 6a and 6b. However, in the present invention, if the bonding members 7a and 7b of the tuning fork-type piezoelectric vibrator 2 are bonded to the two opposing curved surfaces of the first mounting pad 6a and the second mounting pad 6b, respectively, during mounting, slippage in the second direction (X direction) is less likely to occur, and the mounting position can be prevented from shifting.

[0048] Furthermore, the piezoelectric oscillator 1 of the present invention is configured such that the width L1 of the housing portion 31 of the mounting pads 6a and 6b of the package 3 in the long side direction (Y direction, first direction) is within 15% of the length (size) L2 of the housing portion 31 in the long side direction, the center line Q of the joining members 7a and 7b of the tuning fork type piezoelectric vibrator 2 in the first direction is within 15% of the center line P of the housing portion 31 of the mounting pads 6a and 6b in the long side direction, and the end faces of the housing portion 31 of the mounting pads 6a and 6b in the long side direction do not overlap with the base portion 20 of the tuning fork type piezoelectric vibrator 2 in a plan view. With this configuration, it is possible to prevent contact between the tips of the vibrating arms 21 and 22 and the inner wall surface of the package 3, while also preventing short circuits.

[0049] More specifically, a tuning fork-type piezoelectric vibrator 2 having a holding portion 23 that is roughly L-shaped in plan view, as in this embodiment, has a longer longitudinal shape compared to a tuning fork-type piezoelectric vibrator 2 without a holding portion 23. Therefore, there was a risk that the tips of the vibrating arms 21 and 22 would come into contact with the inner wall surface of the package 3 when mounted on the package 3. On the other hand, if the mounting position of the tuning fork-type piezoelectric vibrator 2 is adjusted to prevent contact between the vibrating arms 21 and 22 and the inner wall surface of the package 3, as shown in Figure 6, the base 201 of the tuning fork-type piezoelectric vibrator 200 and the mounting pad 600 of the package would overlap in plan view. Depending on the inclination of the tuning fork-type piezoelectric vibrator 200 in the thickness direction during mounting, there was a risk that the opposite polarity wiring patterns 202 and 203 provided on the base 201 would come into contact with the mounting pad 600 and cause a short circuit.

[0050] As shown in the configuration of the present invention, in addition to making the width L1 in the long-side direction of the housing portion 31 for the mounting pads 6a and 6b of the package 3 smaller than in the conventional method, the tuning fork type piezoelectric vibrator 2 is mounted near the center line P in the long-side direction of the housing portion 31 for the mounting pads 6a and 6b, thereby ensuring sufficient space between the tips of the vibrating arms 21 and 22 and the inner wall surface of the package 3. Furthermore, by making the width L1 in the long-side direction of the housing portion 31 for the mounting pads 6a and 6b of the package 3 smaller than in the conventional method, when the tuning fork type piezoelectric vibrator 2 is mounted, the mounting pads 6a and 6b and the base portion 20 do not overlap in a plan view, and the metal films of the mounting pads 6a and 6b do not come into contact with the first and second lead electrodes 2a and 2b of opposite poles provided on the base portion 20 of the tuning fork type piezoelectric vibrator 2, thereby preventing a short circuit.

[0051] Furthermore, the width L1 of the housing portion 31 of the mounting pads 6a and 6b in the long side direction (Y direction, first direction) is formed to be greater than or equal to the width of the holding portion 23 of the tuning fork-type piezoelectric vibrator 2 in the Y direction. This configuration allows the tuning fork-type piezoelectric vibrator 2 to be held and mounted in the mounting pads 6a and 6b of the package 3 with sufficient holding area (holding strength). In addition, when mounting the tuning fork-type piezoelectric vibrator 2 to the package 3, contact between the inner wall surface of the package 3 and the holding portion 23 of the tuning fork-type piezoelectric vibrator 2 can be prevented.

[0052] Furthermore, this invention is not limited to the configurations of the embodiments described above, and many other embodiments can be obtained. For example, in this embodiment, the holding portion 23 is configured to bend in the +X direction, but it is not limited to this configuration. That is, the holding portion 23 may be configured to bend in the -X direction, or it may be configured to bend in both the +X and -X directions.

[0053] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of the present invention is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the equivalents of the claims. [Industrial applicability]

[0054] The tuning fork type piezoelectric vibration device of the present invention can be used in the manufacturing and sales industry of tuning fork type piezoelectric oscillators equipped with a tuning fork type piezoelectric vibrator. [Explanation of Symbols]

[0055] 1... Tuning fork type piezoelectric oscillator 2…Tuning fork-type piezoelectric vibrator 20…Base 21, 22... Vibrating arm part 23...Holding part 3…Package 31... Detention Unit 32...Double part 34…IC-equipped pad 4…Lid 5…IC 6a...First mounted pad 6b...Second mounted pad 7a, 7b... Joining members

Claims

1. A tuning fork type piezoelectric vibration device comprising a tuning fork type piezoelectric vibrator and a package that houses the tuning fork type piezoelectric vibrator in an internal housing, The aforementioned tuning fork-shaped piezoelectric vibrator is The base and, A pair of vibrating arms extending in a first direction from one end of the base, The base comprises a holding portion that extends from the other end of the base in a direction opposite to the extension direction of the vibrating arm and protrudes in at least one of a second direction perpendicular to the first direction, The aforementioned retaining part is The package has a joint portion that is joined to the joint member at multiple positions spaced apart in the second direction, The aforementioned package is Two vibration-equipped pads, each joined to the aforementioned tuning fork-type piezoelectric vibrator, The housing portion has a stepped portion having two of the aforementioned vibrating element mounting pads on its upper surface, The two vibrating element mounting pads have an upward-convex shape with a curved surface in which their thickness gradually decreases as they approach each other in the short-side direction of the housing portion. The joint portion is located on the adjacent curved surface in the vibrator mounting pad. Tuning fork type piezoelectric vibration device.

2. The tuning fork-type piezoelectric vibrator has at least two metal wiring patterns at its base that are opposite in polarity, The vibrating element mounting pad, in the second direction, superimposes with only one of the two metal wiring patterns that are opposite in thickness to the position where the joint is located. The tuning fork type piezoelectric vibration device according to claim 1.

3. The base of the tuning fork-type piezoelectric vibrator and the vibrator mounting pad of the package are not superimposed in a plan view. A tuning fork type piezoelectric vibration device according to claim 1 or 2.

4. The aforementioned joining member is formed by bumps made of metal. A tuning fork type piezoelectric vibration device according to claim 1 or 2.

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