Piezoelectric vibrating piece, piezoelectric vibrator, and oscillator

Abstract

To improve vibration followability while inhibiting a decrease in the piezoelectric effect.SOLUTION: At a connection portion between a vibration arm portion 7 and widened portions 71 (on both sides of the vibration arm portion), right triangular prism-shaped taper portions 711 are integrally formed to inhibit abrupt mass changes in the longitudinal direction. Inclined portions 713 connected to the taper portions 711, to the widened portion 71 and to the vibration arm portion 7 and having thickness decreasing (thinning) as the distance from the connection portion increases are integrally formed. An upper inclined surface 713u and a lower inclined surface 713d, which are surfaces of each inclined portion 713 (714), are inclined to approach each other and form a ridge line r.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a piezoelectric vibrating piece, a piezoelectric vibrator, and an oscillator, and more particularly to a tuning-fork type piezoelectric vibrating piece and a piezoelectric vibrator. [Background technology]

[0002] For example, in electronic devices such as mobile phones and personal digital assistants, tuning-fork type piezoelectric vibrators using quartz crystal or the like are widely used as devices used as a time source, a timing source for control signals, a reference signal source, etc. In this type of piezoelectric vibrator, a piezoelectric vibrating piece is hermetically sealed in a cavity formed by a package and a lid. Such piezoelectric vibrating pieces and piezoelectric vibrators are required to be miniaturized as the electronic devices they are mounted on become smaller, and as a countermeasure, a wide widened part (weight part) called a hammer head is provided at the tip of the vibrating arm. The widened part provided at the tip of the vibrating arm has a problem that it deteriorates vibration tracking because the mass change from the vibrating arm is large (sudden). Therefore, in order to reduce the deterioration of vibration followability and to suppress abrupt changes in mass, a tapered portion is provided at the connection between the tip of the vibrating arm and the widened portion (for example, Patent Document 1).

[0003] However, the width of the bank between the groove formed in the vibrating arm and the side surface of the vibrating arm becomes wider, and the resistance value increases, which reduces the piezoelectric effect. In particular, the smaller the piezoelectric vibrating piece, the narrower the width of the vibrating arm, and the greater the problem of vibration tracking, but there is also the problem that making the shape of the tapered portion larger reduces the piezoelectric effect. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4356366 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to improve vibration followability while suppressing a decrease in the piezoelectric effect. [Means for solving the problem]

[0006] The present invention provides a piezoelectric vibrating reed comprising: a base; a pair of vibrating arms extending in a line from the base; an expanded portion extending from a connection portion provided on the opposite side of the base of the vibrating arms and formed wider than the width of the vibrating arms; a groove portion formed in the longitudinal direction on at least one of the main surfaces of both vibrating arms; an inclined portion connected to the expanded portion and the vibrating arms on at least one of the two sides in the width direction of the vibrating arms and whose thickness decreases the further away from the connection portion in the longitudinal direction of the vibrating arms; and two systems of excitation electrodes formed on the outer surfaces of the base and the pair of vibrating arms for exciting the pair of vibrating arms. Effect of the Invention

[0007] According to the present invention, a widening portion is provided on at least one of the two sides in the width direction of the vibrating arm, and an inclined portion is connected to the vibrating arm and the thickness decreases the further away from the connection portion in the longitudinal direction of the vibrating arm, thereby improving vibration tracking while suppressing a decrease in the piezoelectric effect. [Brief description of the drawings]

[0008] [Figure 1] 2A and 2B are diagrams illustrating a configuration of a piezoelectric vibrating reed and a cross section of a vibrating arm in the longitudinal direction. [Diagram 2] 13 is a perspective view showing the state of a tapered portion and an inclined portion provided at a connection portion between a vibrating arm portion and an expanded portion. FIG. [Diagram 3] 1A and 1B are an enlarged view, a cross-sectional view, and a diagram showing the change in cross-sectional area of ​​a tapered portion and an inclined portion. [Figure 4] 13 is an explanatory diagram showing the state of a tapered portion and an inclined portion in the second embodiment. FIG. [Diagram 5] 13 is an explanatory diagram showing the state of a tapered portion and an inclined portion in the third embodiment. FIG. [Figure 6] 13 is an explanatory diagram showing the state of a tapered portion and an inclined portion in a fourth embodiment. FIG. [Figure 7] 13 is an explanatory diagram showing the state of a tapered portion and an inclined portion in the fifth embodiment. FIG. [Figure 8] 11 is an explanatory diagram showing the relationship between the ratio of the total volume of a tapered portion and an inclined portion on both sides of a vibrating arm and vibration leakage; FIG. [Figure 9] FIG. [Figure 10] FIG. 2 is an explanatory diagram showing a side cross section of a piezoelectric vibrator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a piezoelectric vibrating piece, a piezoelectric vibrator, and an oscillator of the present invention will be described in detail with reference to FIGS. (1) Overview of the embodiment The piezoelectric vibrating piece 6 of this embodiment is a tuning fork-type piezoelectric vibrating piece, in which a pair of vibrating arms 7 are extended (connected) in the longitudinal direction from one end side of a base 8, and a pair of support arms 9 are formed on the outside of the vibrating arms 7 from the other end side of the base 8 via a connection portion 81, and an extension portion 71 that is wider than the vibrating arms 7 is provided at the tip of the vibrating arms 7.

[0010] Tapered sections 711 and 712 for suppressing abrupt changes in mass in the longitudinal direction are integrally formed at the connection (on both sides of the vibrating arm) between the vibrating arm 7 and the widened section 71. When viewed in the thickness direction of the vibrating arm 7, the tapered sections 711 and 712 have a right-angled triangular prism shape. Furthermore, inclined portions 713 and 714 that are connected to the tapered portion 711 (712), the widened portion 71, and the vibrating arm portion 7 and that become thinner (thinner) as they move away from the connection portion are integrally formed. The upper inclined surface 713u (714u) and the lower inclined surface 713d (714d), which are the surfaces of the inclined portion 713 (714), are inclined so as to approach each other and form a ridgeline r.

[0011] In this embodiment, by providing tapered portions 711, 712 and inclined portions 713, 714 at the connection portion between the widening portion 71 and the vibrating arm portion 7 (hereinafter referred to as the base of the widening portion 71), the change in mass (volume) in the longitudinal direction (change in cross-sectional area in the width direction) at the base of the widening portion 71 is made gentler, thereby improving vibration tracking ability while increasing the number of banks of optimal width, and suppressing a decrease in the piezoelectric effect.

[0012] (2) Details of the embodiment FIG. 1 is a diagram showing the configuration of a piezoelectric vibrating piece 6 according to an embodiment and a partial cross section in the longitudinal direction of a vibrating arm portion 7. As shown in FIG. The piezoelectric vibrating piece 6 is a so-called tuning fork-type vibrating piece formed from a piezoelectric material such as quartz crystal, lithium tantalate, or lithium niobate, and vibrates when a predetermined voltage is applied. In this embodiment, a piezoelectric vibrating piece formed using quartz crystal as the piezoelectric material will be described as an example.

[0013] As shown in FIG. 1(a), the piezoelectric vibrating reed 6 includes a pair of vibrating arms 7a, 7b, a base 8, a pair of supporting arms 9a, 9b, and connecting portions 81a, 81b connecting the base 8 to both supporting arms 9a, 9b. Hereinafter, the length direction of the vibrating arms 7a, 7b (left and right direction in Figure 1(a)) will be referred to as the longitudinal direction, the direction in which the vibrating arms 7a, 7b face each other (up and down direction in Figure 1(a)) will be referred to as the width direction, and the thickness direction of the piezoelectric vibrating piece 6 (up and down direction in Figure 1(b)) will be referred to as the thickness direction.

[0014] A pair of vibrating arms 7a, 7b extending in parallel in the longitudinal direction are connected to one end side (right side in the drawing) of the base 8. On the other hand, the other end of the base 8 is connected to connection portions 81a and 81b which extend to the outside of the base 8 in the width direction. A pair of supporting arms 9a, 9b extending in the longitudinal direction are connected to the ends of the connecting portions 81a, 81b opposite the base portion 8. The pair of supporting arms 9a, 9b are disposed on both outer sides of the vibrating arms 7a, 7b in the width direction.

[0015] The pair of vibrating arms 7a, 7b are arranged parallel to each other, and widened portions 71a, 71b are connected to the ends on the opposite side of the base 8. The pair of vibrating arms 7a, 7b vibrate with the ends on the base 8 side as fixed ends and the widened portions 71a, 71b as free ends. When the width of the vibrating arms 7a, 7b at approximately the center in the longitudinal direction is taken as a reference width, the widened portions 71a, 71b are formed so as to be wider on both sides (in the width direction) than this reference width. The widened portions 71a and 71b have the function of increasing the total weight of the vibrating arms 7a and 7b together with the widened portions 71a and 71b and the moment of inertia during vibration. This makes it easier for the vibrating arms 7a and 7b to vibrate, and the length of the vibrating portion (the vibrating arms 7a and 7b and the widened portions 71a and 71b) can be shortened, resulting in a compact design.

[0016] At the connection portion between the widened portion 71a and the vibrating arm portion 7a, tapered portions 711a, 712a and inclined portions 713a, 714a are provided to suppress a sudden change in the cross-sectional area in the width direction at the boundary surface between the end of the vibrating arm portion 7a and the widened portion 71a, and to reduce the bank portion that is wider than the optimal width. Similarly, tapered portions 711b, 712b and inclined portions 713b, 714b are provided at the connection portion between the widened portion 71b and the vibrating arm portion 7b. The detailed shapes of the tapered portions 711a, 712a, 711b, and 712b and the inclined portions 713a, 714a, 713b, and 714b will be described later with reference to FIGS. In FIG. 1, the inclined portions 713a, 714a, and the inclined portions 713b, 714b are indicated by being shaded.

[0017] In the piezoelectric vibrating piece 6 of this embodiment, although not shown, a weight metal film (consisting of a coarse adjustment film and a fine adjustment film) is formed on the widened parts 71a and 71b to adjust (adjust) the vibration to a predetermined frequency range. For example, by irradiating a laser beam to remove an appropriate amount of this weight metal film, the frequency can be adjusted to keep the frequency of the pair of vibrating arms 7a and 7b within the range of the nominal frequency of the device. It is also possible not to form this weight metal film.

[0018] FIG. 1(b) is a cross-sectional view of the vibrating arms 7a and 7b cut in the width direction (the vertical direction in the figure), as viewed from the base 8 side. As shown in FIG. 1(b), grooves 72a, 72b of a constant width are formed in the pair of vibrating arms 7a, 7b in the longitudinal direction. The grooves 72a, 72b are recessed in the thickness direction on both main surfaces (front and back surfaces) of the pair of vibrating arms 7a, 7b and the widened portions 71a, 71b, and extend from the base 8 side along the longitudinal direction. In this embodiment, the grooves 72a, 72b are formed from the base ends of the vibrating arms 7a, 7b (the ends of the base 8 on the widened portions 71a, 71b side) to the entire vibrating arms 7a, 7b (to the base end of the widened portions 71a, 71b). The grooves 72a and 72b make the pair of vibrating arms 7a and 7b have an H-shaped cross section as shown in FIG. 1(b). This H-shaped cross section can increase the electric field efficiency of the vibrating arms 7a and 7b compared to when the grooves 72a and 72b are not formed. Therefore, when obtaining the same vibration frequency, the vibration loss is small and the CI value (crystal impedance or equivalent series resistance) can be kept low even if the piezoelectric vibrating reed 6 is made smaller. In this embodiment, the grooves 72a, 72b are formed on both main surfaces, but they may be formed on only one of the main surfaces.

[0019] Groove portions 72a, 72b are formed on the main surfaces of the vibrating arms 7a, 7b, so that bank portions 721a, 721b are formed between both outer side surfaces of the vibrating arms 7a, 7b and both inner side surfaces of the groove portions 72a, 72b. The banks 721a and 721b correspond to the vertical bar portions of the H-shaped cross section of the vibrating arms 7a and 7b, excluding the horizontal bar portions of the H shape.

[0020] 1(b), a pair of (two systems) excitation electrodes 91, 92 are formed on the outer surfaces (peripheral surfaces) of the pair of vibrating arms 7a, 7b. The excitation electrodes 91, 92 are electrodes that vibrate the pair of vibrating arms 7a, 7b in a direction approaching or separating them from each other at a predetermined resonance frequency when a voltage is applied, and are formed by patterning on the vibrating arms 7a, 7b in an electrically separated state. Specifically, one excitation electrode 91 is formed mainly in the groove 72a of one vibrating arm 7a and on the side surface of the other vibrating arm 7b in a state in which they are electrically connected to each other. The other excitation electrode 92 is formed mainly in the groove 72b of the other vibrating arm 7b and on the side surface of one vibrating arm 7a in a state where they are electrically connected to each other.

[0021] On one main surface of the piezoelectric vibrating piece 6 (the surface opposite to that in Figure 1(a)), two systems of mount electrodes are formed on the support arms 9a and 9b (not shown), and two systems of wiring electrodes electrically connected to both of these mount electrodes are formed on the connection parts 81a and 81b and the base 8. The mounting electrodes of the supporting arms 9a and 9b are connected to the electrode pads 20A and 20B by bonding materials 51a, 52a, 51b, and 52b when the piezoelectric vibrating reed 6 is mounted on mounting portions 14A and 14B formed on a package 2, which will be described later with reference to Fig. 9. In Fig. 1(b), the bonding materials 51a, 52a, 51b, and 52b are indicated by dotted lines.

[0022] The first system of mount electrodes formed on the support arm 9a is connected to the excitation electrode 92 (see Figure 1 (b)) via a routing electrode, and the second system of mount electrodes formed on the support arm 9b is connected to the excitation electrode 91 via a routing electrode (not shown). A voltage is applied to the two excitation electrodes 91 and 92 via a pair of mount electrodes.

[0023] The excitation electrodes 91, 92, the mount electrodes, and the wiring electrodes are, for example, a laminated film of chromium (Cr) and gold (Au), which is formed on a base of a chromium film that has good adhesion to quartz, and then a thin gold film is applied to the surface. However, this is not limited to this case, and for example, a thin gold film may be further laminated on the surface of a laminated film of chromium and nichrome (NiCr), or a single layer film of chromium, nickel (Ni), aluminum (Al), titanium (Ti), etc. may also be used.

[0024] The excitation electrodes 91, 92, the mount electrode, and the wiring electrode are formed in the same manner as in the past. That is, before forming each electrode, an electrode material is formed on the entire piezoelectric vibrating piece 6, including the inside of the grooves 72a, 72b. This film formation is performed by vapor deposition or sputtering of the electrode material. Then, the portions for forming the excitation electrodes 91, 92, the mount electrode, and the wiring electrode are left, and the other portions are removed by photolithography, thereby forming two systems of electrode lines.

[0025] In addition, since the piezoelectric vibrator 1 of this embodiment has a left-right symmetrical structure, the two symmetrically arranged parts, such as the vibrating arm portion 7a and the vibrating arm portion 7b, are represented by the same number, and the distinguishing symbols a and b are used to distinguish between the two parts. In the following description, the distinction symbols a and b will be omitted as appropriate, and for example, when the vibrating arm portion is referred to as 7, it will be described as referring to each of the portions (vibrating arm portion 7a and vibrating arm portion 7b). The same is true for the other symbols A, B, u, and d that distinguish parts of the object (left and right, top and bottom).

[0026] Next, the state of the tapered portions 711, 712 and the inclined portions 713, 714 disposed at the connection portion between the vibrating arm portion 7 and the widened portion 71 will be described. FIG. 2 is a perspective view showing the state of the tapered portions 711 and 712 and the inclined portions 713 and 714. As shown in FIG. FIG. 3 is an enlarged view, a cross-sectional view, and a diagram showing the change in cross-sectional area of ​​the tapered portions 711 and 712 and the inclined portions 713 and 714 and their surroundings. The cross section of the vibrating arm 7 indicated by diagonal lines in FIG. 2 and FIG. 3(b) is a cross section seen in the direction of the arrow PP in FIG. 3(a). As described above, the tapered portions 711 and 712 and the inclined portions 713 and 714 are formed symmetrically, so the following description will focus on the tapered portion 711 and the inclined portion 713.

[0027] As shown in the perspective view of FIG. 2, tapered portions 711 and 712 and inclined portions 713 and 714 are formed on both sides of the connection portion with the widened portion 71 in the vibrating arm portion 7. The tapered portions 711 and 712 have a right-angled triangular prism shape when viewed from the main surface side. In this embodiment, the tapered portions 711 and 712 have a right-angled isosceles triangular prism shape, but other shapes are also possible.

[0028] The length in the thickness direction of the tapered portions 711, 712 is the same as that of the vibrating arm portion 7, and the upper and lower surfaces of the tapered portions 711, 712 and both main surfaces of the vibrating arm portion 7 are located on the same plane. As a result, it is also possible to consider that the tapered portions 711, 712 (and their upper and lower surfaces) are integrated with the vibrating arm portion 7 and form part of the bank portion 721. Hereinafter, the tapered portions 711, 712 will be collectively referred to as the bank portion 721, except when they are to be distinguished from each other in the following description. The tapered portions 711 and 712 are integrally formed with the vibrating arm portion 7 and the widened portion 71 . In this way, by providing tapered portions 711, 712 at the connection between the vibrating arm 7 and the widened portion 71, it is possible to suppress a sudden change in mass in the longitudinal direction of the vibrating arm 7 and the resulting deterioration in vibration tracking ability.

[0029] Here, if one wishes to make the mass change in the longitudinal direction of the vibrating arm 7 more gradual, this can be achieved by increasing the longitudinal length of the tapered portions 711, 712 (the length connecting to the side of the vibrating arm 7). However, when tapered portions 711 and 712 are lengthened in the longitudinal direction, the area where bank portion 721 is wider increases accordingly, which causes a problem of reduced piezoelectric effect. That is, the bank width is formed to be the optimum width near the center in the longitudinal direction of the vibrating arm 7. In contrast, if the tapered portions 711 and 712 are lengthened in the longitudinal direction, the portion (wide portion) wider than the optimum width including the lengthened portion increases, and conversely, the length of the bank portion 721, which is the optimum width, becomes shorter. Therefore, as the width of the bank portion 721 increases, the area where the resistance value increases increases, and the piezoelectric effect decreases.

[0030] Therefore, in the piezoelectric vibrating piece 6 of this embodiment, the tapered portion 711 (712), the widened portion 71, and the inclined portions 713 and 714 formed integrally with the vibrating arm portion 7 are provided. In the following description, the tapered portions 711 and 712 and the inclined portions 713 and 714 are formed in line symmetry with respect to the groove portion 72, so that the inclined portion 713 will be described. 2 and 3(b), the inclined portion 713 is formed so that the portion connected to the tapered portion 711 is the thickest. In this embodiment, the maximum thickness of the inclined portion 713 is formed to be smaller than the thickness of the vibrating arm portion 7, so that the inclined portion 713 is connected to the tapered portion 711 closer to the center in the thickness direction than the main surface (bank portion), but it is also possible to make the maximum thickness of the inclined portion 713 the same as the thickness of the vibrating arm portion 7.

[0031] When the maximum thickness of the inclined portion 713 is set to the same thickness as the thickness of the vibrating arm portion 7, if a tapered portion 711 is formed, the tapered portion 713 is formed to have the maximum thickness at the position where the tapered portion 711 and the vibrating arm portion 7 intersect, and the thickness is gradually reduced from that position toward the vibrating arm portion side end point t2. On the other hand, in the case of the embodiments and modified examples described below in which the tapered portion 711 is not formed, the widened portion 71 is formed to the same maximum thickness as the vibrating arm 7 at the position where the end face of the widened portion 71 intersects with the vibrating arm 7, and the thickness gradually decreases from that position toward the vibrating arm side end point t2. In this way, even if the maximum thickness of the inclined portion 713 is made the same as the thickness of the vibrating arm portion 7, the upper inclined surface 713u inclines downward and the lower inclined surface 713d inclines upward toward the ridge line r, so that the wide portion of the bank portion 721 does not increase.

[0032] The inclined portion 713 is formed so that its thickness decreases as it moves away from the tapered portion 711 along the base end face of the widening portion 71, and also so that its thickness decreases as it moves away from the tapered portion 711 along the side face of the vibrating arm portion 7. In other words, the inclined portion 713 has its surfaces, that is, upper inclined surface 713u and lower inclined surface 713d, which approach each other by inclining so that the distance between them becomes smaller as they move away from the tapered portion 711, and the tip portion where the two come into contact forms a ridge line r. In the inclined portion 713 of this embodiment, the upper inclined surface 713u is inclined downward and the lower inclined surface 713d is inclined upward at the same angle, and therefore, they have the same area. In this way, the ridge line r connects the tapered portion 711, the widened portion 71, and the vibrating arm portion 7 on at least one of the two sides in the width direction of the vibrating arm portion 7, and is formed by the upper inclined surface on one main surface side and the lower inclined surface on the other main surface side being inclined and approaching each other. As shown in FIG. 3(b), the widened portion side end point t1 and the vibrating arm side end point t2, which are both end points of the ridge line r, are located at the center in the thickness direction of the widened portion 71 and the vibrating arm 7, respectively.

[0033] Here, the position in the width direction of an end point t1 on the widened portion side of the ridge line r formed by the inclined portion 713 will be described. In this embodiment (including other embodiments and modifications), the widened portion side end point t1 is formed so as to be located in the outermost region when the width of the widened portion 71 is divided into five equal parts. In this way, by forming the position of the widened portion side end point t1 in the outermost range divided into five equal parts, the change in cross-sectional area at the base of the widened portion 71 (the connection portion between the widened portion 71 and the vibrating arm portion 7) can also be made gentle.

[0034] Regarding the end point t1 on the widened portion side, it may be formed in the outer (side surface end portion side of the widened portion 71) range when the width from the side surface end portion of the widened portion 71 to the side surface of the vibrating arm portion 7 is bisected on the side where the inclined portion 713 is inclined.

[0035] The relationship between the sizes of the tapered portion 711 and the inclined portion 713 is as follows. That is, when the area of the tapered portion 711 is T and the area (horizontal projected area) of the inclined portion 713 is K when the piezoelectric vibrating piece 6 is viewed in plan (see Fig. 3(a)), it is formed such that the area K of the inclined portion is larger than the area T of the tapered portion (T < K). In this way, by making the area K of the inclined portion larger than the area T of the tapered portion, the change in mass (volume) in the longitudinal direction (change in cross-sectional area in the width direction) at the joint between the vibrating arm portion 7 and the widened portion 71 can be made smoother. In addition, similarly in each of the modification examples described later, it is preferable that the area K of the inclined portion > the area T of the tapered portion.

[0036] In this way, the inclined portion 713 is formed such that the thickness becomes smaller as it is farther from the tapered portion 711, the widened portion 71, and the vibrating arm portion 7. Furthermore, the inclined portion 713 is formed such that its maximum thickness is smaller than the thickness of the vibrating arm portion 7, so that the upper inclined surface 713u is located below the upper main surface, and the lower inclined surface 713d is located above the lower main surface. As a result, the piezoelectric vibrating piece 6 of the present embodiment has no decrease (increase in the wide portion) in the portion of the optimum width in the embankment portion 721 compared to the case where only the tapered portion 711 is provided, and the loss of the piezoelectric effect can be suppressed.

[0037] Furthermore, the inclined portion 713 has a gradually increasing thickness in the thickness direction (the distance between the upper inclined surface 713u and the lower inclined surface 713d becomes wider) as it approaches the widened portion 71 from the end point t2 on the vibrating arm portion side. Therefore, compared to the case where only the tapered portion 711 with a constant thickness and an increasing width is provided, the abrupt mass change at the connection portion between the vibrating arm portion 7 and the widened portion 71 is further alleviated, and the vibration can be made more stable. Therefore, by providing the inclined portion 713, it is also possible to make the tapered portion 711 smaller, and by making the tapered portion 711 smaller, the optimum width portion in the bank portion 721 can be further increased.

[0038] FIG. 3( c ) shows the change in cross-sectional area caused by the tapered portion 711 and the inclined portion 713 . In this figure, the horizontal axis represents the position L along the longitudinal direction of the vibrating arm portion 7 and the widened portion 71, and the vertical axis represents the change S in the cross-sectional area. In the figure, as shown in the upper left, the dashed line represents the cross-sectional area change to the left of the center line in the longitudinal direction (not shown) of the vibrating arm 7, and the solid line represents the cross-sectional area change to the right. Note that, since the tapered portion 711 and the inclined portion 713, and the tapered portion 712 and the inclined portion 714 in this embodiment are formed symmetrically, the cross-sectional area change is the same, and therefore only the solid line is shown.

[0039] In addition, the dotted line shown in the figure shows, for comparison, the case where only a tapered portion 711 is formed at the connection between the vibrating arm portion 7 and the widened portion 71 (a conventional example), and shows the case where the tapered portion 711 is formed up to the ridge line r position of the inclined portion 713. 3(c), from the origin (0) position on the horizontal axis to the horizontal axis position L1 (the position corresponding to the end point t2 of the ridge line r on the vibrating arm side), there is neither the tapered portion 711 nor the inclined portion 713, so the cross-sectional area is a constant value c. This constant value c is 1 / 2 of the volume (cross-sectional area) of the vibrating arm 7.

[0040] If there were no inclined portion and only tapered portion 711 was formed from the position of horizontal axis L2 (comparative example), the thickness of tapered portion 711 would be constant, and the cross-sectional area would change linearly as shown by the dotted line.

[0041] On the other hand, in this embodiment, the cross-sectional area between the vibrating arm side end point t2 (position on horizontal axis L1) of the vibrating arm 7 and the position where the tapered portion 711 is formed along the longitudinal direction of the vibrating arm 7 (position on horizontal axis L2) is the sum of the volume c of the vibrating arm 7 and the cross-sectional area of ​​the inclined portion 713, since only the inclined portion 713 is present. The cross-sectional area change of the inclined portion 713 alone increases quadratically because the cross section is triangular. Therefore, in reality, a gentle curve due to a quadratic function is formed between the horizontal axis L1 (the position of the end point t2 on the vibrating arm side) and the horizontal axis L3 (the position connecting to the widened portion 71), but in FIG. 3(c), it is shown as a simplified straight line for convenience of drawing representation.

[0042] Between the position of the horizontal axis L2 and the position of the horizontal axis L3, where the inclined portion 713 and the tapered portion 711 are present, the cross-sectional area changes as a linear function of the tapered portion 711 in addition to the quadratic function.

[0043] As shown in the graph of FIG. 3(c), in the piezoelectric vibrating piece 6 of this embodiment, in addition to the tapered portion 711, an inclined portion 713 is provided at the connection portion between the vibrating arm portion 7 and the widened portion 71. As a result, compared to the change in cross-sectional area (shown by the dotted line) in the comparative example in which only the tapered portion 711 is arranged, in this embodiment, the change in cross-sectional area at the connection portion between the vibrating arm portion 7 and the widened portion 71 can be reduced without increasing the width of the bank portion due to the tapered portion 711. That is, looking at the change in cross-sectional area around the horizontal axis L3, in the comparative example, the cross-sectional area changes significantly from the vertical axis S1 to S4, whereas in this embodiment, the change in cross-sectional area is smaller than in the comparative example, as the cross-sectional area changes from a cross-sectional area larger than S1 to S4. In this way, in this embodiment, the change in cross-sectional area in the longitudinal direction can be made gentle. In other words, abrupt changes in cross-sectional area can be avoided, and this can improve vibration tracking. In particular, the effect of being able to reduce the change in cross-sectional area at the connection between the vibrating arm portion 7 and the widened portion 71 is significant. In addition, since the shape and size of the tapered portion 711 are the same in this embodiment and the comparative example, the width of the bank is the same. Therefore, by providing the inclined portion 713, the bank with the optimal width is not reduced, and the decrease in the piezoelectric effect can be suppressed.

[0044] Next, a piezoelectric vibrating piece 6 according to a second embodiment will be described. Fig. 4 is an explanatory diagram showing the state of the tapered portion and the inclined portion in the second embodiment, and similarly to Fig. 3 explained in the first embodiment, shows an enlarged view, a cross-sectional view, and a change in cross-sectional area around the tapered portions 711, 712 and the inclined portions 713, 714. The same applies to Figs. 5 to 7 showing the other embodiments below. In the first embodiment described above, the case where the tapered portions 711, 712 and the inclined portions 713, 714 are formed on both sides of the connection portion (base) between the vibrating arm portion 7 and the widened portion 71 has been described. In contrast, the second embodiment is similar in that tapered portions 711, 712 of the same size as in the first embodiment are formed on both sides of the vibrating arm 7, but an inclined portion is formed only on one side of the vibrating arm 7, and no inclined portion is formed on the other side. That is, as shown in Fig. 4, only the inclined portion 714 is formed, and the inclined portion 713 on the opposite side is not formed. Note that, contrary to the display in Fig. 4, only the inclined portion 713 may be formed, and the inclined portion 714 may not be formed.

[0045] Moreover, in the second embodiment, the maximum thickness in the thickness direction of the inclined portion 714 (the thickness of the portion connected to the tapered portion 712) is made thicker than in the first embodiment (see Figures 4(b) and 3(b)). However, in the second embodiment, similar to the first embodiment, the maximum thickness of the inclined portion 714 is formed to be thinner than the thickness of the vibrating arm portion 7, but as explained as a modified example of the first embodiment, the maximum thickness of the inclined portion 714 may be formed to be the same thickness as the vibrating arm portion 7.

[0046] The change in cross-sectional area of ​​the base portion in the second embodiment is shown in FIG. On the left side of the vibrating arm 7, only the tapered portion 711 is formed and no inclined portion is formed, so that the cross-sectional area changes in the same manner as in the comparative example described by the dotted line in FIG. 3(c). In other words, as shown by the wide dotted line, from the origin (0) of the horizontal axis to position L2 on the horizontal axis where the tapered portion 711 begins, the volume of the vibrating arm 7 is c (a constant value), and from position L2 on the horizontal axis where the tapered portion 711 exists to position L3, the cross-sectional area changes linearly.

[0047] On the other hand, since a tapered portion 712 and an inclined portion 714 are formed on the right side of the vibrating arm 7, as shown by the solid line, the cross-sectional area changes only due to the inclined portion 714 from the position of the vibrating arm side end point t2 where the inclined portion 714 begins along the horizontal axis. The cross-sectional area is changed by the inclined portion 714 and the tapered portion 712 . However, the inclined portion 714 in the second embodiment is formed thicker than in the first embodiment, and further, the widened portion side end point t1 is formed further outward (to the side position of the widened portion 71), so that the change in cross-sectional area at the connection portion between the vibrating arm portion 7 and the widened portion 71 can be made smaller. The dotted line in FIG. 4(c) represents the change in cross-sectional area due to the tapered portion 711 and the inclined portion 713 in the first embodiment (the solid line portion in FIG. 3(c)).

[0048] Next, a piezoelectric vibrating piece 6 according to a third embodiment will be described. FIG. 5 is an explanatory diagram showing the state of the tapered portion and the inclined portion in the third embodiment. In the first embodiment described above, the tapered portions 711, 712 on both sides of the vibrating arm 7 and the inclined portions 713, 714 on both sides are formed to have the same size. In contrast to this, in the third embodiment, the tapered portions and inclined portions on both sides of the vibrating arm 7 are formed to have different sizes. 5(a), the tapered portion 711 and the inclined portion 713 formed on the left side of the vibrating arm 7 are formed to have the same size as in the first embodiment. In contrast, the tapered portion 712 on the right side is formed to have a smaller size than the tapered portion 711 on the left side. Further, the right inclined portion 714 is formed to have a larger size in a plan view than the left inclined portion 713. As a result, the position of the vibrating arm side end point t2 of the right inclined portion 714 is located closer to the base 8 (not shown) side than the left inclined portion 713.

[0049] As for the change in cross-sectional area, as shown in FIG. 5(c), for the left-side tapered portion 711 and inclined portion 713, which are the same size as in the first embodiment, the cross-sectional area increases from the horizontal axis L1 where the inclined portion 713 begins, as indicated by the solid line in FIG. 3(c), and further increases at a large gradient from the horizontal axis 2L where the tapered portion 711 also begins. On the other hand, the change in cross-sectional area of ​​the right-side tapered portion 712 and inclined portion 714 begins earlier (closer to the origin than the horizontal axis L1) than the left-side tapered portion 711, and the increase in the inclination of the tapered portion 712 begins at a position closer to the L3 side than the horizontal axis L2.

[0050] In the third embodiment, the thickness of the right-side inclined portion 714 is made thicker than the thickness of the left-side inclined portion 713. However, the thickness of the left-side inclined portion 713, which has a smaller planar area than the right-side inclined portion 714, which has a larger planar area, may also be made thicker. The difference in cross-sectional area change at each horizontal axis position between the left and right sides shown in FIG. 5(c) (the width between the dashed dotted line representing the left side and the solid line representing the right side) can be narrowed.

[0051] Next, a piezoelectric vibrating reed 6 according to a fourth embodiment will be described. FIG. 6 is an explanatory diagram showing the state of the tapered portion and the inclined portion in the fourth embodiment. In the first to third embodiments described above, the inclined portions 713, 714 formed on the left and right sides of the vibrating arm 7 are symmetrical in the width direction with the ridge line r as the center when viewed in the thickness direction. That is, when the inclined portions 713, 714 are cut horizontally along the ridge line r, the cross-sectional area on the upper inclined surface 713u side is the same as the cross-sectional area on the lower inclined surface 713d side. In the fourth embodiment, as shown in FIG. 6(a), the area when viewed in a plane is the same as in the first embodiment for the tapered portion 711 and the inclined portion 713 on the left side of the vibrating arm 7, and the area is the same as in the third embodiment for the tapered portion 712 and the inclined portion 714 on the right side. 6(b), on the left side of the vibrating arm 7, the position of the ridge line r in the thickness direction is located above the center in the thickness direction of the vibrating arm 7, so that the inclination angle of the lower inclined surface 713d is larger than the inclination angle of the upper inclined surface 713u. In other words, the inclination of the lower inclined surface 713d is steeper than that of the upper inclined surface 713u. The inclination angle may be reversed.

[0052] On the other hand, on the right side of the vibrating arm 7, the position of the widened portion side end point t1 in the thickness direction of the inclined portion 714 differs from the position of the vibrating arm side end point t2 in the thickness direction, so that the ridge line r is inclined. Specifically, the widened portion side end point t1 is located at the center in the thickness direction, whereas the vibrating arm side end point t2 is located below the center in the thickness direction.

[0053] In the fourth embodiment, the tapered portions 711 and 712 and the inclined portions 713 and 714 of the vibrating arm portion 7 have been described with reference to FIG. In contrast to this, tapered portion 711 and inclined portion 713 on the left side may be formed to have the same shapes as tapered portion 712 and inclined portion 714 on the right side. Conversely, tapered portion 712 and inclined portion 714 on the right side may be formed to have the same shapes as tapered portion 711 and inclined portion 713 on the left side. In this way, even in the embodiments and modified examples in which the left and right shapes are different, it is possible to make one side the same shape as the other side (a shape symmetrical about the vibrating arm 7).

[0054] Next, a piezoelectric vibrating piece 6 according to a fifth embodiment will be described. FIG. 7 is an explanatory diagram showing the state of the tapered portion and the inclined portion in the fifth embodiment. In the first to fourth embodiments described above, the tapered portions 711 and 712 formed on the left and right sides of the vibrating arm 7 were triangular prism shapes (right-angled triangles in plan view). Also, the inclined portions 713 and 714 had straight ridge lines r connecting the widened portion side end point t1 and the vibrating arm side end point t2. In contrast to this, in the fifth embodiment, the widened portion 71 of the tapered portion and the portion not connected to the vibrating arm portion 7 (the portion corresponding to the hypotenuse of the right-angled triangle) are not straight lines in a plan view. Also, the ridge line r connecting the widened portion side end point t1 and the vibrating arm side end point t2 is not a straight line.

[0055] Specifically, as shown in Fig. 7(a), the surface of the taper portion 711 on the left side of the vibrating arm 7 that is not connected to the vibrating arm 7 and the widened portion 71 is a single plane in other embodiments, whereas in this embodiment, as shown in Fig. 7(a), it is formed of two surfaces that bend inward in the center (toward the intersection line between the vibrating arm 7 and the widened portion 71). Note that, although Fig. 7(a) describes a case where it is composed of two surfaces, it may be composed of n surfaces (n≧2), such as three surfaces or four surfaces. On the other hand, the left inclined portion 713 of the vibrating arm 7 is connected to multiple surfaces of the tapered portion 711. The ridge line r formed by the upper inclined surface 713u and the lower inclined surface 713d of the inclined portion 713 is also bent inward at two points. In addition, the edge line r may bend at multiple points, such as one point or three points, in addition to bending at two points, and the bending direction may be formed so as to bend outward rather than inward (the same applies to the tapered portion 711). Also, tapered portion 711 may have a right-angled triangular prism shape similar to the other embodiments, with only the ridge line r of inclined portion 713 bending inward or outward. Conversely, it is also possible for the ridge line r of inclined portion 713 to be a straight line, and for tapered portion 711 to be configured with multiple surfaces bending inward.

[0056] On the other hand, in the fifth embodiment, the taper portion 712 on the right side of the vibrating arm 7 is formed so that the portion not connected to the widened portion 71 or the vibrating arm 7 (the portion corresponding to the hypotenuse of the right triangle) is curved inwardly in plan view. Conversely, it is also possible to form it so as to be curved outwardly. Although the ridge line r of the right inclined portion 714 is formed to be a straight line as in the other embodiments and modifications, it is also possible to form it into a curved shape that is concave inward or protrudes outward in a plan view. In this case, the inclined portion 714 can also be formed into a right-angled triangular prism shape as in the first to fourth embodiments.

[0057] In the above second to fifth embodiments, unlike the first embodiment, the case has been described in which the shapes of the left tapered portion 711 and inclined portion 713 in the vibrating arm 7 are different from the shapes of the right tapered portion 712 and inclined portion 714. In this way, the left and right shapes of the connection (base) between the vibrating arm 7 and the widened portion 71 are different, and therefore the total volume of the tapered portion and the inclined portion is different on the left and right. Therefore, the influence on vibration leakage caused by this difference was investigated. FIG. 8 shows the relationship between the ratio of the total volume of the tapered portion and the inclined portion on both sides of the vibrating arm portion 7 and the vibration leakage. Regarding the influence of vibration leakage due to the difference in total volume between the left and right, the size (C chamfer size) of the connection (base) between the vibrating arm 7 and the widened portion 71 was changed and an analysis was performed using the finite element method. FIG. 8(a) shows the simulation results of vibration leakage for each of the investigated cases 1 to 5, showing the ratio of the total volume on the left and right and the value of the vibration leakage (ppm). Here, the ratio (%) represents (total volume on the right side / total volume on the left side)×100.

[0058] FIG. 8(b) is a graph showing the simulation results of 1 to 5 that were investigated. From the graph shown in FIG. 8(b), it was determined that in order to keep vibration leakage within the generally acceptable range of 20 ppm, the left / right ratio of the total volume must be within 140%. Therefore, in the second to fifth embodiments and the various modified examples described above, the difference in total volume between the tapered portions and the inclined portions on the left and right sides of the vibrating arm 7 is formed to be within 40%.

[0059] Although the piezoelectric vibrating piece 6 in the first embodiment and its modified examples have been described above, the first embodiment can be modified as follows, including the second to fifth embodiments. Also, each modified example can be combined in any desired manner. (1) In the embodiment described above, the case where the tapered portion and the inclined portion are formed on both sides of the vibrating arm portion 7a and the vibrating arm portion 7b has been described. (a) Alternatively, the tapered portion may be formed only on one side, and the inclined portions may be formed on both sides. In this case, the inclined portion on the side where the tapered portion is formed is connected to the tapered portion, the widened portion, and the vibrating arm portion 7 on the side opposite the ridge line r, as in the embodiment described above, and the inclined portion on the side where the tapered portion is not formed is connected to the widened portion and the vibrating arm portion 7 on the side opposite the ridge line. (b) Conversely, tapered portions may be formed on both sides of the vibrating arm, and the vibrating arm 7 may be formed on either one of the sides. (c) In addition, a tapered portion may not be formed on either side of the vibrating arm 7, and an inclined portion may be formed only on one side of the vibrating arm 7, or an inclined portion may be formed on both sides of the vibrating arm 7.

[0060] (2) In the embodiment described above, the case where the tapered portions and the inclined portions of the same size are formed on both sides of the vibrating arm portion 7 has been described. (d) Alternatively, the tapered portion on one side may be formed larger than the tapered portion on the other side. (e) Furthermore, in either case where the tapered portions on both sides are the same size, or where the sizes of the tapered portions are different as in (d) above, the inclined portion on one side may be formed larger than the inclined portion on the other side. (f) In the tapered portion, the length of the portion connected to the vibrating arm portion 7 and the length of the portion connected to the widened portion 71 are the same, but either one of the lengths may be formed to be longer than the other. That is, while the shape of the tapered portion in plan view is a right-angled isosceles triangle in the embodiment described above, in this modified example, it is a right-angled triangle with two adjacent sides of different lengths.

[0061] (3) In the embodiment described above, the inclined portion is formed symmetrically above and below (on the upper inclined surface side and the lower inclined surface side) in the thickness direction with respect to the ridge line r. That is, the ridge line r of the inclined portion is formed so as to be located at the center in the thickness direction of the vibrating arm portion 7. (g) On the other hand, the ridgeline r of the inclined portion may be located on either of the main surfaces. In other words, the volume of the upper inclined surface side of the ridgeline r may be different from the volume of the lower inclined surface side of the ridgeline r. (h) In the embodiment described above, the position of the end point t1 on the widened portion side in the thickness direction of the ridge line r of the inclined portion and the position of the end point t2 on the vibrating arm portion side may be different positions. In this case, the ridge line r is inclined with respect to the horizontal plane.

[0062] (4) In the embodiment described above, the inclined portions on both sides of the vibrating arm 7 are formed to have the same shape and size. (i) On the other hand, the shape and / or size of either or both of the tapered portion and the inclined portion may be made different on both sides of the vibrating arm portion 7 .

[0063] (5) In the embodiment, the inclined portion has a thickness that decreases with increasing distance from the tapered portion toward both the end point t1 on the widened portion side and the end point 2 on the vibrating arm side. (j) In contrast to this, the thickness of the inclined portion may be formed so that the thickness decreases the further away from the end point 2 on the vibrating arm side, but the thickness is constant toward the end point t1 on the widened portion side. In this case, no ridge line r is formed by the upper and lower inclined surfaces of the inclined portion, and instead, at the open end side of the upper inclined surface and the open end side of the lower inclined surface, a triangular (in some embodiments, an isosceles triangle) end face is formed, with the side in contact with the widening portion 71 as the base and the vibrating arm side end point t2 as the vertex.

[0064] In addition, in the embodiments and modifications described above, a piezoelectric vibrating reed has been described. On the other hand, it is also possible to form an oscillator in which the piezoelectric vibrating reed of the embodiment or modified example described above is electrically connected to an integrated circuit as an oscillator.

[0065] Next, a piezoelectric vibrator 1 on which the piezoelectric vibrating piece 6 described in each embodiment or modification is mounted will be described. FIG. 9 is an exploded perspective view of a piezoelectric vibrator 1 including a side arm type piezoelectric vibrating piece 6 according to the above-described embodiment or modification. As shown in Figure 9, the piezoelectric vibrator 1 of this embodiment is a ceramic package type surface mount type vibrator that includes a package 2 having an airtight sealed cavity C therein, and a piezoelectric vibrating piece 6 housed in the cavity C. The package 2 is formed in a roughly rectangular parallelepiped shape, and includes a package body 3 and a sealing plate 4. The sealing plate 4 is joined to the package body 3 to form a cavity C between the package body 3 and the sealing plate 4. The package body 3 includes a first base substrate 10 and a second base substrate 11 that are bonded together in a stacked state, and a seal ring 12 that is bonded onto the second base substrate 11.

[0066] At the four corners of the first base substrate 10 and the second base substrate 11, cutout portions 15 having a quarter-circular arc shape in plan view are formed over the entire thickness direction of both base substrates 10, 11. The first base substrate 10 and the second base substrate 11 are fabricated, for example, by stacking and bonding two wafer-like ceramic substrates, forming a matrix of through holes penetrating both ceramic substrates, and then cutting both ceramic substrates into a lattice shape using each through hole as a reference. At this time, the through holes are divided into four to form the cutout portions 15.

[0067] The first base substrate 10 and the second base substrate 11 are made of ceramic, and specific ceramic materials include, for example, HTCC (High Temperature Co-Fired Ceramic) made of alumina, and LTCC (Low Temperature Co-Fired Ceramic) made of glass ceramic.

[0068] The upper surface of the first base substrate 10 corresponds to the bottom surface of the cavity C. The second base substrate 11 is placed on the first base substrate 10 and is bonded to the first base substrate 10 by sintering or the like. That is, the second base substrate 11 is integrated with the first base substrate 10. As will be described later, a connection electrode (not shown) is formed between the first base substrate 10 and the second base substrate 11 in a state where it is sandwiched between both the base substrates 10 and 11.

[0069] A through portion 11a is formed in the second base substrate 11. The through portion 11a is formed in a rectangular shape in a plan view with rounded corners. The inner surface of the through portion 11a constitutes a part of the side wall of the cavity C. Mounting portions 14A and 14B that protrude inward are provided on both inner surfaces facing each other in the width direction of the through portion 11a. The mounting portions 14A and 14B are formed in approximately the center in the longitudinal direction of the through portion 11a. The mounting portions 14A and 14B are formed to have a length of 1 / 3 or more of the longitudinal length of the through portion 11a.

[0070] The seal ring 12 is a conductive frame-shaped member that is slightly smaller than the outer shapes of the first base substrate 10 and the second base substrate 11, and is joined to the upper surface of the second base substrate 11. Specifically, the seal ring 12 is joined to the second base substrate 11 by baking with a brazing material such as silver brazing or a solder material, or by welding to a metal bonding layer formed on the second base substrate 11 (for example, by electrolytic plating, electroless plating, vapor deposition, sputtering, or the like).

[0071] The material of the seal ring 12 may be, for example, a nickel-based alloy, and may be selected from Kovar, Elinvar, Invar, 42-alloy, etc. In particular, it is preferable to select a material for the seal ring 12 that has a thermal expansion coefficient close to that of the first base substrate 10 and the second base substrate 11, which are made of ceramic. For example, when alumina with a thermal expansion coefficient of 6.8×10−6 / °C is used as the first base substrate 10 and the second base substrate 11, it is preferable to use Kovar with a thermal expansion coefficient of 5.2×10−6 / °C or 42-alloy with a thermal expansion coefficient of 4.5 to 6.5×10−6 / °C as the seal ring 12.

[0072] The sealing plate 4 is a conductive substrate overlaid on the seal ring 12, and is hermetically joined to the package body 3 by being bonded to the seal ring 12. The space defined by the sealing plate 4, the seal ring 12, the through portion 11a of the second base substrate 11, and the upper surface of the first base substrate 10 functions as a cavity C that is hermetically sealed.

[0073] Examples of the welding method for the sealing plate 4 include seam welding by contacting a roller electrode, laser welding, ultrasonic welding, etc. In order to ensure the welding between the sealing plate 4 and the seal ring 12, it is preferable to form a bonding layer of nickel, gold, or the like, which has good compatibility with each other, at least on the lower surface of the sealing plate 4 and the upper surface of the seal ring 12.

[0074] A pair of electrode pads 20A, 20B, which are connection electrodes with the piezoelectric vibrating reed 6, are formed on the upper surfaces of the mounting portions 14A, 14B of the second base substrate 11. In addition, a pair of external electrodes 21A, 21B are formed on the lower surface of the first base substrate 10 with a gap therebetween in the longitudinal direction of the package 2. The electrode pads 20A, 20B and the external electrodes 21A, 21B are single-layer films made of a single metal formed by, for example, vapor deposition or sputtering, or laminated films in which different metals are laminated. The electrode pads 20A, 20B and the external electrodes 21A, 21B are electrically connected to each other via second through electrodes 22A, 22B formed in the mounting portions 14A, 14B of the second base substrate 11, a connection electrode (not shown) formed between the first base substrate 10 and the second base substrate 11, and a first through electrode (not shown) formed in the first base substrate 10.

[0075] The piezoelectric vibrating reed 6 is housed in a cavity C of the hermetically sealed package 2 in a state where it is mounted on mounting portions 14A and 14B by a pair of supporting arms 9a and 9b. That is, as shown in FIG. 9, the piezoelectric vibrating piece 6 has mounting electrodes provided on the supporting arms 9a, 9b electrically and mechanically bonded to the electrode pads 20A, 20B (or to the metallized layer if a metallized layer is formed on the upper surface) on the mounting portions 14A, 14B via bonding materials 51a, 51b, respectively. In this manner, in the piezoelectric vibrating piece 6 of this embodiment, each of the supporting arms 9a, 9b is joined and held (supported at two points) on the mounting portions 14A, 14B at two points in the length direction (longitudinal direction).

[0076] The bonding materials 51a and 51b are conductive and have the property of being fluid in the early bonding stage and solidifying to exhibit bonding strength in the later bonding stage. For example, a conductive adhesive such as silver paste or a metal bump is preferably used. When the bonding materials 51a and 51b are made of a conductive adhesive, they are applied by a dispenser nozzle supported on a moving head of an application device. In this embodiment, the size of each bonding material depends on the size of the piezoelectric vibrator 1. For example, in the case of a small piezoelectric vibrator 1 having a width of 1.0 mm and a length of 1.2 mm, the bonding material is applied to a radius of about 0.1 mm.

[0077] Fig. 10 is a cross-sectional view along the longitudinal direction of the piezoelectric vibrator 1 in which the piezoelectric vibrating piece 6 is mounted in the package 2 shown in Fig. 9. However, in order to show the first through electrode 23B, the cross-sectional position at that portion is shifted. On the mounting surfaces (the surfaces facing the sealing plate 4) of the mounting portions 14A and 14B of the second base substrate 11, electrode pads 20A and 20B are formed over almost the entire surfaces. Meanwhile, external electrodes 21A and 21B extending in the short direction (X direction) are formed on both ends in the longitudinal direction (Y direction) on the outer bottom surface of the first base substrate 10. These electrode pads 20A, 20B and external electrodes 21A, 21B are either single-layer films made of a single metal formed, for example, by vapor deposition or sputtering, or laminated films in which different metals are laminated, and the electrode pad 20A and the external electrode 21A are mutually conductive, and the electrode pad 20B and the external electrode 21B are mutually conductive.

[0078] That is, as shown in Fig. 10, a first through electrode 23B that is electrically connected to the external electrode 21B and penetrates the first base substrate 10 in the thickness direction is formed on the first base substrate 10. Furthermore, a second through electrode 22B that is electrically connected to the electrode pad 20B and penetrates the mounting portion 14B in the thickness direction is formed approximately in the center (see Fig. 9) of the mounting portion 14B of the second base substrate 11. Then, a connection electrode 24B that connects the first through electrode 23B and the second through electrode 22B is formed between the first base substrate 10 and the second base substrate 11 (mounting portion 14B). In this manner, the electrode pad 20B and the external electrode 21B are electrically connected to each other via the second through electrode 22B, the connection electrode 24B, and the first through electrode 23B.

[0079] On the other hand, as shown by dotted lines in Fig. 10, a first through electrode 23A that is electrically connected to the external electrode 21A and penetrates the first base substrate 10 in the thickness direction is formed on the first base substrate 10, and a second through electrode 22A that is electrically connected to the electrode pad 20A and penetrates the mounting portion 14A in the thickness direction is formed approximately in the center (see Fig. 9) of the mounting portion 14A of the second base substrate 11. Then, a connection electrode 24A that connects the first through electrode 23A and the second through electrode 22A is formed between the first base substrate 10 and the second base substrate 11 (mounting portion 14A). In this manner, the electrode pad 20A and the external electrode 21A are electrically connected to each other via the second through electrode 22A, the connection electrode 24A, and the first through electrode 23A.

[0080] In addition, both connection electrodes 24A, 24B are not shaped to linearly connect the first through electrodes 23A, 23B and the second through electrodes 22A, 22B, but are formed along the area where the second base substrate 11 and the first base substrate 10 abut in order to avoid exposure within the cavity C.

[0081] The piezoelectric vibrating reed 6 is housed in a cavity C of the hermetically sealed package 2 in a state where it is mounted on mounting portions 14A and 14B by a pair of supporting arms 9a and 9b. That is, as shown in Figures 10 and 1(a), in the piezoelectric vibrating piece 6, the mounting electrodes formed on the supporting arms 9a, 9b are electrically and mechanically joined to the electrode pads 20A, 20B (or to the metallized layer if a metallized layer is formed on the upper surface) on the mounting portions 14A, 14B by bonding materials 51a, 51b, 52a, and 52b, respectively. In this manner, in the piezoelectric vibrating piece 6 of this embodiment, each of the supporting arms 9a and 9b is bonded and held (two-point supported) on the mounting parts 14A and 14B at two points in the length direction. However, the supporting arms 9a and 9b do not need to be bonded to the mounting parts 14A and 14B at two points, and may be bonded to one point in the center. In this case, various methods are possible for the bonding material, such as forming it in the center with the same size as in Figures 9 and 10, forming it in an elliptical shape in the center, or forming it in an oval shape by connecting the bonding materials 51a and 52a, and 51b and 52b. Also, it may be applied and bonded at three or more points. A silicone-based conductive adhesive is used as the bonding materials 51a, 51b, 52a, and 52b, and is applied onto the electrode pads 20A and 20B by a dispenser nozzle supported on a moving head of an application device.

[0082] To operate the piezoelectric vibrator 1 configured in this manner, a predetermined voltage is applied to the external electrodes 21A, 21B. When a predetermined voltage is applied to the external electrodes 21A, 21B, a current flows through the two excitation electrodes 91, 92, and the pair of vibrating arms 7a, 7b vibrate at a predetermined resonance frequency, for example, in a direction approaching or separating from each other (width direction), due to an inverse piezoelectric effect caused by an electric field generated between the two excitation electrodes 91, 92. The vibration of the pair of vibrating arms 7a, 7b is used as a time source, a timing source for a control signal, a reference signal source, or the like.

[0083] The piezoelectric vibrator 1 described above is used as a timing source for time signals, control signals, reference signal sources, etc. in radio-controlled clocks, mobile phones, and portable information terminal devices, and as measuring instruments such as gyro sensors.

[0084] In this embodiment, the piezoelectric vibrating piece 6 is formed to have a width of 0.6 mm and a length of 1.0 mm, but may have other sizes. That is, a piezoelectric vibrating piece 6 having a size corresponding to the size of the piezoelectric vibrator 1 is used. For example, in the case of a piezoelectric vibrating piece 6 used in a piezoelectric vibrator 1 having a width of 0.8 mm and a length of 1.0 mm, if it is a side arm type, a piezoelectric vibrating piece 6 having a width of 0.5 mm and a length of 0.7 mm is used.

[0085] From the above-described embodiments and modifications, the piezoelectric vibrating piece and the piezoelectric vibrator can be configured as follows. (Configuration 1) a base, A pair of vibrating arms extending side by side from the base; a widened portion extending from a connection portion provided on the opposite side of the base portion of the vibrating arm portion and formed wider than the width of the vibrating arm portion; A groove portion is formed in at least one of the two main surfaces of the two vibrating arms in a longitudinal direction; an inclined portion that is connected to the widened portion and the vibrating arm portion on at least one of both sides in the width direction of the vibrating arm portion and that has a thickness that decreases as it moves away from the connection portion in the longitudinal direction of the vibrating arm portion; two systems of excitation electrodes formed on the base and on outer surfaces of the pair of vibrating arms for exciting the pair of vibrating arms; A piezoelectric vibrating piece comprising: (Configuration 2) The connection portion includes a tapered portion formed on at least one of both sides of the width direction of the vibrating arm portion and the widened portion, the tapered portion having a width in the width direction narrowing from the widened portion side toward the base portion side. 2. The piezoelectric vibrating piece according to configuration 1. (Configuration 3) The tapered portion is formed on both sides of the vibrating arm in a width direction, The inclined portion is connected to the tapered portion, the widened portion, and the vibrating arm portion. 3. The piezoelectric vibrating piece according to configuration 1 or 2. (Configuration 4) The tapered portions formed on both sides have different areas when the piezoelectric vibrating piece is viewed in a plan view. The piezoelectric vibrating piece according to configuration 1, 2, or 3, (Configuration 5) The inclined portion has a thickness that decreases with increasing distance from the tapered portion, the widened portion, and the connection portion with the vibrating arm portion. 5. The piezoelectric vibrating piece according to any one of configurations 1 to 4, (Configuration 6) The inclined portion and the tapered portion are formed such that an area of ​​the inclined portion is larger than an area of ​​the tapered portion when the piezoelectric vibrating piece is viewed in a plan view. 6. The piezoelectric vibrating piece according to any one of configurations 1 to 5, (Configuration 7) The inclined portion is formed on both sides of the vibrating arm in a width direction, and the inclined portions formed on both sides have the same or different areas when the piezoelectric vibrating piece is viewed in a plane. 7. The piezoelectric vibrating piece according to any one of configurations 1 to 6, (Configuration 8) The inclined portion and the tapered portion are formed on both sides of the vibrating arm in a width direction, The total volume of the inclined portion and the tapered portion is within 1.4 times the total volume of the other side. 8. The piezoelectric vibrating piece according to any one of configurations 1 to 7, (Configuration 9) The inclined portion is connected to the main surface of the vibrating arm portion on the center side in the thickness direction of the vibrating arm portion. 6. The piezoelectric vibrating piece according to any one of configurations 1 to 5. (Configuration 10) A package having a mounting portion therein; A piezoelectric vibrating piece according to any one of configurations 1 to 9, which is mounted on the mounting portion via a bonding material; an external electrode formed from the mounting portion to the outside of the package; A piezoelectric vibrator comprising: (Configuration 11) A piezoelectric vibrator according to configuration 10, The piezoelectric vibrator is electrically connected to an integrated circuit as an oscillator. 1. An oscillator comprising:

[0086] (Configuration 21) A base, A pair of vibrating arms extending side by side from the base; a widened portion extending from the vibrating arm portion on the opposite side of the base portion of the vibrating arm portion and formed wider than the width of the vibrating arm portion; A groove portion is formed in at least one of the two main surfaces of the two vibrating arms in a longitudinal direction; a tapered portion connected to the vibrating arm portion and the widened portion and formed on at least one side of the width direction of the vibrating arm portion, the tapered portion having a width narrowing from the widened portion side toward the base portion side; an inclined portion that is connected to the tapered portion, the widened portion, and the vibrating arm portion on at least one of both sides in the width direction of the vibrating arm portion, and that is an upper inclined surface on one main surface side and a lower inclined surface on the other main surface side that are inclined to approach each other and form a ridge line; two systems of excitation electrodes formed on the base and on outer surfaces of the pair of vibrating arms for exciting the pair of vibrating arms; A piezoelectric vibrating piece comprising: (Configuration 22) The tapered portions formed on both sides of the vibrating arm have different lengths in contact with the widened portion. 22. The piezoelectric vibrating piece according to claim 21, (Configuration 23) The inclined portion is formed on both sides of the vibrating arm portion. 23. The piezoelectric vibrating piece according to claim 21 or 22. (Configuration 24) The inclined portions formed on both sides of the vibrating arm have the same or different distances from a position where the vibrating arm intersects with the widened portion to a position where the ridge line contacts with the widened portion. The piezoelectric vibrating piece according to configuration 21, 22, or 23, characterized in that (Configuration 25) The ridge line is located at a position where it contacts the widened portion in an outermost region when the widened portion is divided into five equal parts in the width direction of the vibrating arm portion. 25. The piezoelectric vibrating piece according to any one of configurations 21 to 24, (Configuration 26) The ridge line is located at a center in a thickness direction of the vibrating arm, or is located on one of the main surfaces from the center. The piezoelectric vibrating piece according to any one of configurations 21 to 25, (Configuration 27) The ridge line is in contact with the widened portion and the ridge line is in contact with the vibrating arm at different height positions in a thickness direction of the vibrating arm. The piezoelectric vibrating piece according to any one of configurations 21 to 26, (Configuration 28) The inclined portion is connected to the main surface of the vibrating arm portion on the center side in the thickness direction of the vibrating arm portion. The piezoelectric vibrating piece according to any one of configurations 21 to 27, (Configuration 29) A package having a mounting portion therein; A piezoelectric vibrating piece according to any one of the configurations 21 to 28, which is mounted on the mounting portion via a bonding material; an external electrode formed from the mounting portion to the outside of the package; A piezoelectric vibrator comprising: (Configuration 30) A piezoelectric vibrator according to configuration 29, The piezoelectric vibrator is electrically connected to an integrated circuit as an oscillator. 1. An oscillator comprising: [Explanation of symbols]

[0087] 1 Piezoelectric vibrator 2 Package 3 Package Body 4 Sealing plate 6 Piezoelectric vibrating piece 7 Vibrating arm 8 base 9 Support arm 10 First base substrate 11 Second base substrate 11a Penetration 12 Seal ring 14A, 14B mounting section 15 Notch 20A, 20B Electrode pads 21A, 21B external electrode 22A, 22B Through electrode 23A, 23B Through electrode 24A, 24B connection electrodes 51, 51 Bonding material 71 Widening section 72 Groove 81 Connection 91, 92 Excitation electrode 711, 712 Tapered section 713, 714 Slope section 713u, 714u upper slope 713d, 714d Lower slope 721 Bank r Ridge t1 Widening side end point t2 Vibrating arm side end point

Claims

1. A base and A pair of vibrating arms extending from the base portion side by side; a widened portion extending from a connection portion provided on the opposite side of the base portion of the vibrating arm portion and formed wider than the width of the vibrating arm portion; A groove portion is formed in at least one of the two main surfaces of the two vibrating arms in a longitudinal direction; an inclined portion that is connected to the widened portion and the vibrating arm portion on at least one of both sides in the width direction of the vibrating arm portion and that has a thickness that decreases as it moves away from the connection portion in the longitudinal direction of the vibrating arm portion; two systems of excitation electrodes formed on the base and on outer surfaces of the pair of vibrating arms for exciting the pair of vibrating arms; A piezoelectric vibrating piece comprising:

2. The connection portion includes a tapered portion formed to connect the vibrating arm portion and the widened portion on at least one of both sides in the width direction of the vibrating arm portion, the tapered portion having a width in the width direction narrowing from the widened portion side toward the base portion side. The piezoelectric vibrating piece according to claim 1 .

3. The tapered portion is formed on both sides of the vibrating arm in a width direction, The inclined portion is connected to the tapered portion, the widened portion, and the vibrating arm portion. The piezoelectric vibrating piece according to claim 2 .

4. The tapered portions formed on both sides have different areas when the piezoelectric vibrating piece is viewed in a plan view. The piezoelectric vibrating piece according to claim 3 .

5. the inclined portion has a thickness that decreases with increasing distance from the tapered portion, the widened portion, and the connection portion with the vibrating arm portion; The piezoelectric vibrating piece according to claim 3 .

6. The inclined portion and the tapered portion are formed such that an area of ​​the inclined portion is larger than an area of ​​the tapered portion when the piezoelectric vibrating reed is viewed in a plan view. The piezoelectric vibrating piece according to claim 3 .

7. The inclined portion is formed on both sides of the vibrating arm in a width direction, and the inclined portions formed on both sides have the same or different areas when the piezoelectric vibrating piece is viewed in a plane. The piezoelectric vibrating piece according to claim 1 .

8. The inclined portion and the tapered portion are formed on both sides of the vibrating arm in a width direction, The total volume of the inclined portion and the tapered portion is within 1.4 times the total volume of the other side. The piezoelectric vibrating piece according to claim 2 .

9. The inclined portion is connected to the main surface of the vibrating arm portion on the center side in the thickness direction of the vibrating arm portion. The piezoelectric vibrating piece according to any one of claims 1 to 5.

10. A package having a mounting portion therein; The piezoelectric vibrating piece according to any one of claims 1 to 9, which is mounted on the mounting portion via a bonding material; an external electrode formed from the mounting portion to the outside of the package; A piezoelectric vibrator comprising:

11. A piezoelectric vibrator according to claim 10, The piezoelectric vibrator is electrically connected to an integrated circuit as an oscillator.

1. An oscillator comprising:

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