Piezoelectric device, piezoelectric vibration piece and piezoelectric wafer

Abstract

To provide a piezoelectric device which reduces the risk of a piezoelectric vibration piece being in contact with a bottom face, etc., of a package in a case where the piezoelectric vibration piece is mounted in the package.SOLUTION: A piezoelectric device comprises: a package 2 including a bottom plate 13 which is formed rectangular in a planar view, a bank part 11 which is provided along an edge of the bottom plate, and adhesive pads 16 and 17 which are provided on one end side in a longer side direction of an inner region which is enclosed by the bank part; a piezoelectric vibration element 3 which includes an excitation part in a flat plate shape, a mesa part having a thickness which is larger than that of the excitation part and an inclined part which is positioned between the excitation part and the mesa part and of which the thickness is gradually larger from the excitation part toward the mesa part, and is formed rectangular in the planar view; and a conductive adhesive 18 which adheres the inclined part of the piezoelectric vibration piece to the adhesive pads at positions where the mesa part and the inclined part are opposed to the adhesive pads. The piezoelectric vibration element has ruggedness which is formed from the inclined part to the inside of the mesa part, and the adhesive is positioned in a recess.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a piezoelectric device, a piezoelectric vibrating piece mounted on the piezoelectric device, and a piezoelectric wafer on which a plurality of piezoelectric vibrating pieces are formed. [Background technology]

[0002] Piezoelectric devices are widely used in various electronic devices such as mobile phones and personal computers, mainly for frequency selection and control. Piezoelectric devices can be classified into piezoelectric resonators, piezoelectric oscillators, SAW devices, optical devices, etc., depending on their function. Crystal resonators and crystal oscillators, which use quartz crystal as the piezoelectric element, are widely known and commonly used.

[0003] For example, Patent Document 1 discloses a quartz crystal unit in which a so-called inverted mesa quartz crystal blank is mounted inside a package. The quartz crystal blank has a vibrating portion, which is essential for it to function as a quartz crystal blank, and a fixing portion for fixing the quartz crystal blank to the package (particularly, Figure 9(a)). The fixing portion is thicker than the vibrating portion, and the fixing portion, which is the edge of the quartz crystal blank, is held in place by a conductive adhesive. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-80577 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when one end of the quartz crystal substrate is held in place by a conductive adhesive, the other end that is not held in place by the conductive adhesive tends to sag and come into contact with the bottom surface of the package, etc.

[0006] The present disclosure has been made in consideration of such problems, and its purpose is to provide a piezoelectric device in which the risk of the piezoelectric vibrating piece coming into contact with the bottom surface of a package or the like when the piezoelectric vibrating piece is mounted in the package is reduced, a piezoelectric vibrating piece used therein, and a piezoelectric wafer consisting of a plurality of piezoelectric vibrating pieces. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, there is provided a piezoelectric device comprising: a package including a bottom plate that is rectangular in plan view, a bank portion provided along the edge of the bottom plate, and an adhesive pad provided on one end side of a long side of an inner region surrounded by the bank portion; a piezoelectric vibrating piece that is rectangular in plan view and includes a flat excitation portion, a mesa portion that is thicker than the excitation portion, and an inclined portion that is located between the excitation portion and the mesa portion and whose thickness gradually increases from the excitation portion toward the mesa portion; and an adhesive that adheres the inclined portion of the piezoelectric vibrating piece to the adhesive pad at a position where the mesa portion and the inclined portion face the adhesive pad, wherein the piezoelectric vibrating piece has irregularities formed from the inclined portion into the mesa portion, and the adhesive is located in the recess.

[0008] According to one aspect of the present disclosure, there is provided a piezoelectric vibrating piece having "a flat excitation portion, a mesa portion having a thickness greater than that of the excitation portion, an inclined portion located between the excitation portion and the mesa portion and gradually increasing in thickness from the excitation portion toward the mesa portion, and unevenness formed from the inclined portion to the inside of the mesa portion, where an adhesive is positioned when mounted."

[0009] According to one aspect of the present disclosure, there is provided a piezoelectric wafer having "a plurality of piezoelectric vibrating pieces, each of which has a flat excitation portion, a mesa portion having a thickness greater than that of the excitation portion, an inclined portion located between the excitation portion and the mesa portion and gradually increasing in thickness from the excitation portion toward the mesa portion, and unevenness formed from the inclined portion to the inside of the mesa portion and on which an adhesive is positioned when mounted; a frame portion to which the piezoelectric vibrating pieces are connected; and connection portions connecting each of the piezoelectric vibrating pieces to the frame portion." [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a piezoelectric device in which the risk of the piezoelectric vibrating piece coming into contact with the bottom surface of a package or the like when the piezoelectric vibrating piece is mounted in a package is reduced, a piezoelectric vibrating piece used therefor, and a piezoelectric wafer consisting of a plurality of piezoelectric vibrating pieces.

[0011] It should be noted that the above effects are merely examples for the sake of convenience of explanation, and the effects of the present disclosure are not limited to these. In addition to the above effects, the present disclosure can achieve any of the effects described herein. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view of a crystal oscillator according to a first embodiment. [Figure 2] 2(a) is an end view taken along dashed line AA in FIG. 1, FIG. 2(b) is a top view of the crystal oscillator according to the first embodiment, and FIG. 2(c) is an end view taken along dashed line BB in FIG. 2(a). [Figure 3] FIG. 3(a) is a side view of the quartz crystal vibrating piece included in the quartz crystal oscillator according to the first embodiment, and FIG. 3(b) is a surface view of the quartz crystal vibrating piece included in the quartz crystal oscillator according to the first embodiment. [Figure 4] FIG. 4(a) is a side view of the crystal vibrating piece included in the crystal oscillator according to the first embodiment, and FIG. 4(b) is a rear view of the crystal vibrating piece included in the crystal oscillator according to the first embodiment. [Figure 5]FIG. 5(a) is a plan view of the quartz crystal wafer according to the first embodiment, FIG. 5(b) is an enlarged view of region R1 in FIG. 5(a), and FIG. 5(c) is a rear view of the quartz crystal vibrating piece with recesses formed therein. [Figure 6] FIG. 6(a) is a side view of a quartz crystal vibrating piece according to the first modification of the first embodiment, FIG. 6(b) is a front view of the quartz crystal vibrating piece according to the first modification of the first embodiment, and FIG. 6(c) is a back view of the quartz crystal vibrating piece according to the first modification of the first embodiment. [Figure 7] FIG. 7(a) is a side view of a quartz crystal vibrating piece according to the second modification of the first embodiment, FIG. 7(b) is a front view of the quartz crystal vibrating piece according to the second modification of the first embodiment, and FIG. 7(c) is a back view of the quartz crystal vibrating piece according to the second modification of the first embodiment. [Figure 8] FIG. 8(a) is a rear view of the quartz crystal vibrating piece according to the second embodiment, and FIG. 8(b) is a rear view of the quartz crystal vibrating piece according to a modified example of the second embodiment. [Figure 9] FIG. 3 is an end view of the crystal oscillator according to the third embodiment, similar to FIG. 2(a). [Figure 10] FIG. 10 is an end view of the quartz crystal resonator according to the fourth embodiment, similar to FIG. 2(a). DETAILED DESCRIPTION OF THE INVENTION

[0013] Below, with reference to the drawings, a crystal oscillator and a crystal resonator, which are examples of piezoelectric devices of the present disclosure, a crystal vibrating piece, which is an example of a piezoelectric vibrating piece of the present disclosure, and a crystal wafer, which is an example of a piezoelectric wafer of the present disclosure, will be described in detail. Note that the present disclosure is not limited to the content described below and can be implemented with any modifications within the scope of the present disclosure. Furthermore, the drawings used in each embodiment are schematic illustrations of the crystal oscillator, crystal resonator, crystal vibrating piece, and crystal wafer of the present disclosure. To facilitate understanding, some parts may be emphasized, enlarged, reduced, or omitted, and the scale or shape of each component may not be accurately represented. Furthermore, some numerical values ​​used in each embodiment and its modified examples are merely examples and can be changed as necessary. The same reference symbols are used to designate common components in the drawings.

[0014] (First embodiment) First, the basic structure of a crystal oscillator and a crystal vibrating piece according to the present disclosure will be described with reference to FIGS. 1 to 4. FIG. 1 is a perspective view of a crystal oscillator according to this embodiment. FIG. 2(a) is an end view taken along dashed line AA in FIG. 1, particularly an end view of the long side of the crystal oscillator. FIG. 2(b) is a top view of the crystal oscillator according to this embodiment, particularly showing the internal structure of the mounted crystal vibrating piece. FIG. 2(c) is an end view taken along dashed line BB in FIG. 2(a), particularly an end view of the short side of the crystal oscillator. FIG. 3(a) is a side view of a crystal vibrating piece included in the crystal oscillator according to this embodiment, particularly a side view in one direction showing the connection configuration related to the front electrodes of the crystal vibrating piece. FIG. 3(b) is a front view of a crystal vibrating piece included in the crystal oscillator according to this embodiment. FIG. 4(a) is a side view of a crystal vibrating piece included in the crystal oscillator according to this embodiment, particularly a side view in another direction (opposite to the one direction) showing the connection configuration related to the back electrodes of the crystal vibrating piece. FIG. 4(b) is a rear view of the crystal vibrating piece included in the crystal oscillator according to this embodiment, and particularly shows the application position of the conductive adhesive.

[0015] 1 and 2(a) to 2(c), a crystal oscillator 1, which is an example of a piezoelectric device, has a crystal oscillator package 2 (hereinafter simply referred to as package 2), a crystal vibrating piece 3 and an IC chip 4 mounted in a recessed mounting space 2a of the package 2, and a metal cover (lid) 5 for sealing the mounting space 2a. The crystal oscillator 1 is an electronic component that integrates the crystal vibrating piece 3, which is an example of a piezoelectric vibrating piece, and the IC chip 4, which is an oscillation circuit, in a single package, and is capable of generating a stable frequency and a regular reference signal.

[0016] The package 2 is a ceramic package formed by stacking multiple ceramics on the surface of which a desired metal pattern is formed. Specifically, the package 2 has a laminated structure including an outer frame wall 11, which is a bank portion with an opening of a predetermined size, an inner frame wall 12, which has a smaller opening and a smaller thickness than the outer frame wall 11, and a bottom plate 13, which is rectangular in plan view. In particular, the outer frame wall 11 is provided along the edge of the bottom plate 13, and the inner frame wall 12 is provided in an inner area surrounded by the outer frame wall 11. With this laminated structure, the package 2 has a mounting space 2a, which is recessed and stepped, for mounting the crystal vibrating piece 3 and the IC chip 4. Furthermore, an area for mounting the IC chip 4 is formed on the surface of the bottom plate 13 in the mounting space 2a, and multiple pedestals 14 for installing electrode pads are stacked around the periphery of this area.

[0017] Here, the shape of the package 2 is a rectangular parallelepiped, and is rectangular when viewed from above (FIG. 2(b)). In the following, the thickness direction of the crystal oscillator 1 and the package 2 is referred to as the vertical direction, and the direction perpendicular to the vertical direction is referred to as the horizontal direction. The horizontal direction may also be distinguished as the long side direction (longitudinal direction) and the short side direction (shorter side direction) of the crystal oscillator 1 and the package 2. Furthermore, for each component, the surface located above in the vertical direction may also be referred to as the front surface, and the surface located below may also be referred to as the back surface.

[0018] A sealing conductor pattern 15 is formed on the exposed surface (the surface located on the upper vertical side) of the outer frame wall 11 of the package 2. The planar shape of the conductor pattern 15 is frame-like, just like the outer frame wall 11. A cover 5 is bonded onto the conductor pattern 15 by known metal bonding. This seals the mounting space 2a of the package, and the mounting space 2a is sealed using a vacuum or a gas such as nitrogen.

[0019] Two crystal resonator element mounting terminals 16, 17, which are adhesive pads, are formed on the exposed surface (the surface located vertically at the top) of the inner frame wall 12 of the package 2. In particular, the crystal resonator element mounting terminals 16, 17 are provided on one end of the long side in the inner region surrounded by the outer frame wall 11. The crystal resonator element 3 is mounted on the crystal resonator element mounting terminals 16, 17 via a conductive adhesive 18. The crystal resonator element mounting terminals 16, 17 are electrically connected to external connection terminals 20a, 20b, 20c, and 20d (described later) via connection wiring (not shown) provided inside the package 2.

[0020] Four external connection terminals 20a, 20b, 20c, and 20d are formed at the four corners of the back surface of the bottom plate 13 of the package 2. Furthermore, terminals 21 electrically connected to the electrodes of the IC chip 4 are formed on the surface of each of the bases 14 mounted on the bottom plate 13. For example, if the IC chip 4 has six electrodes, six bases 14 and six terminals 21 are provided, and each electrode is electrically connected to each terminal 21 by wire bonding. The presence of the bases 14 makes it possible to align the height of the electrode-forming surface of the IC chip 4 with the terminals 21, thereby improving the accuracy of wire bonding. The number of electrodes is not limited to six, and the IC chip 4 may be a flip-chip type element. In this case, the shape and number of the bases 14 and terminals 21 are appropriately changed.

[0021] As can be seen from Figures 3(a), 3(b), 4(a), and 4(b), the quartz crystal vibrating piece 3 is composed of a flat excitation portion 3a at one end, a mesa portion 3b at the other end that is thicker than the excitation portion 3a, and an inclined portion 3c located between the excitation portion 3a and the mesa portion 3b. The quartz crystal vibrating piece 3 is rectangular in plan view. Furthermore, as shown in Figure 2(b), the quartz crystal vibrating piece 3 is mounted so that its long and short sides are aligned with the long and short sides of the crystal oscillator 1. In other words, the long and short sides of the quartz crystal vibrating piece 3 coincide with the long and short sides of the crystal oscillator 1, respectively.

[0022] The excitation portion 3a has a thickness corresponding to the frequency at which the crystal oscillator 1 oscillates, and is the portion that generates the required vibrations. In contrast, the mesa portion 3b is provided to improve the adhesive strength and ease of bonding of the crystal vibrating piece 3. The inclined portion 3c has a shape in which its thickness gradually increases from the excitation portion 3a toward the mesa portion 3b. This shape is formed due to the characteristics of the crystal structure of the crystal when the excitation portion 3a is made to a predetermined thickness by etching.

[0023] The quartz-crystal vibrating piece 3 also has an unevenness 30 formed from the inclined portion 3c to the inside of the mesa portion 3b. In this embodiment, the unevenness 30 is composed of two recesses 31, 32 arranged side by side in the short-side direction of the quartz-crystal vibrating piece 3. That is, the unevenness 30 is composed of the recessed shapes of the two recesses 31, 32, a convex shape located between the recesses 31, 32, and a convex shape at the edge of the quartz-crystal vibrating piece 3. In particular, in this embodiment, the two recesses 31, 32 are formed so that the inward side is cut from the inclined surface on the back side of the inclined portion 3c, and the side surfaces of the recesses 31, 32 located inside the inclined portion 3c are inclined similarly to the inclined surface. In other words, the two recesses 31, 32 have a shape that is cut so that they are inclined from the back side of the quartz-crystal vibrating piece 3 toward the front side in the mesa portion 3b and the inclined portion 3c, and extend to a position identical in height to the excitation portion 3a in the vertical direction. Furthermore, as can be seen from Figures 2(a), 2(c), and 4(b), when the quartz crystal vibrating piece 3 is mounted in the package 2, the conductive adhesive 18 is positioned in the two recesses 31 and 32.

[0024] Electrodes are formed on the front and back surfaces of the quartz crystal vibrating piece 3, allowing a voltage to be applied to the quartz crystal vibrating piece 3. Specifically, as can be seen from FIGS. 3(a) and 3(b), a first surface electrode 40 and a second surface electrode 50 are formed on the front surface of the quartz crystal vibrating piece 3. The first surface electrode 40 is composed of an excitation electrode 41 formed on the front surface of the excitation portion 3a, a pad electrode 42 formed on the front surface of the inclined portion 3c, and a connection electrode 43 connecting the excitation electrode 41 and the pad electrode 42. Here, the pad electrode 42 and the connection electrode 43 form an extraction electrode on the front surface. The second surface electrode 50 is formed juxtaposed to the pad electrode 42 on the front surface of the inclined portion 3c, and has the same dimensions and shape as the pad electrode 42.

[0025] As can be seen from FIGS. 4(a) and 4(b), a first back surface electrode 60 and a second back surface electrode 70 are formed on the back surface of the quartz-crystal vibrating piece 3. The first back surface electrode 60 is composed of an excitation electrode 61 formed on the back surface of the excitation portion 3a, a pad electrode 62 formed on the inclined surface that is the back surface of the inclined portion 3c, and a connection electrode 63 that connects the excitation electrode 61 and the pad electrode 62. Here, the pad electrode 62 and the connection electrode 63 form an extraction electrode on the back surface side. Also, as can be seen from FIGS. 3(b) and 4(a), the pad electrode 62 is formed so as to face the second front surface electrode 50 formed on the front surface side of the quartz-crystal vibrating piece 3. Furthermore, the second back surface electrode 70 is formed juxtaposed to the pad electrode 62 on the inclined surface that is the back surface of the inclined portion 3c, and has the same dimensions and shape as the pad electrode 62. As can be seen from FIGS. 3(a), 3(b) and 4(b), the second back surface electrode 70 is formed so as to face the pad electrode 42 formed on the front surface side of the quartz-crystal vibrating piece 3.

[0026] As shown in Fig. 3(a), the first surface electrode 40 formed on the surface side of the quartz-crystal vibrating piece 3 is electrically connected to the second back surface electrode 70 via a side surface electrode 80 formed on a side surface of the quartz-crystal vibrating piece 3. Here, as shown in Fig. 4(b), the conductive adhesive 18 located in the recess 32 protrudes from the recess 32 so as to contact the second back surface electrode 70, and is electrically connected to the excitation electrode 41 via the second back surface electrode 70, the side surface electrode 80, the pad electrode 42, and the connection electrode 43. In contrast, the conductive adhesive 18 located in the recess 31 protrudes from the recess 31 so as to contact the pad electrode 62, and is electrically connected to the excitation electrode 61 via the pad electrode 62 and the connection electrode 63.

[0027] The quartz-crystal vibrating piece 3 is then fixed in place by the conductive adhesive 18 located in the recesses 31 and 32. Specifically, at the positions where the mesa portion 3b and the inclined portion 3c correspond to the quartz-crystal-vibrating-piece mounting terminals 16 and 17, the portions where the inclined portion 3c is formed are adhered to the quartz-crystal-vibrating-piece mounting terminals 16 and 17 by the conductive adhesive 18. In particular, the recesses 31 and 32 prevent the conductive adhesive 18 from spreading toward the mesa portion 3b, and instead spread toward the excitation portion 3a. This means that the quartz-crystal vibrating piece 3 is not held by the end of the quartz-crystal vibrating piece 3 where the mesa portion 3b is located, but is held by the portion of the quartz-crystal vibrating piece 3 near the center where the inclined portion 3c is located. In other words, the quartz-crystal vibrating piece 3 is held between the mesa portion 3b and the excitation electrode 61.

[0028] Holding the quartz crystal vibrating piece 3 in this manner achieves adhesion near the center of gravity of the quartz crystal vibrating piece 3, preventing the excitation portion 3a from sagging compared to when the quartz crystal vibrating piece 3 is held by the flat back surface of the mesa portion 3b. Furthermore, compared to when the recesses 31 and 32 are not formed, the recesses 31 and 32 act as guides to control the spread of the conductive adhesive 18, making it easier to hold the quartz crystal vibrating piece 3 near the center of gravity and increasing the adhesive area in the recesses 31 and 32. This further improves the stability of the mounting of the quartz crystal vibrating piece 3 and prevents the excitation portion 3a, located on the opposite side from the adhesive fixing portion, from coming into contact with the package 2.

[0029] In the above example, the pad electrode 62 is provided only on the inclined portion 3c, but the pad electrode 62 may be provided so as to continue to the periphery of the inclined portion 3c and the recessed portion 31. Similarly, the second back surface electrode 70 may be provided so as to continue to the periphery of the inclined portion 3c and the recessed portion 31. In this case as well, the adhesive area is increased, so that electrical continuity with the conductive adhesive 18 can be more reliably achieved.

[0030] Next, a method for manufacturing a quartz crystal wafer W, which is a piezoelectric wafer according to the present disclosure, and a quartz crystal vibrating piece 3 will be described with reference to Figure 5. Figure 5(a) is a plan view of a quartz crystal wafer as an example of a piezoelectric wafer according to this embodiment. Figure 5(b) is an enlarged view of region R1 in Figure 5(a). Figure 5(c) is a rear view of the quartz crystal vibrating piece 3 with recesses 31 and 32 formed therein.

[0031] First, prepare a quartz crystal wafer W with a roughly circular planar shape, as shown in Figure 5(a). For example, it may be an AT-cut quartz crystal cut from a rough quartz crystal. However, the planar shape is not limited to a circular shape and may be rectangular, and the cut is not limited to an AT-cut but may be other cuts such as a two-turn cut such as a Z-cut or an SC-cut.

[0032] Next, a metal film for forming an etching-resistant mask is formed on the front and back surfaces of the quartz-crystal wafer W. Subsequently, the metal film is processed using well-known photolithography techniques to form etching-resistant masks for defining the outline of the quartz-crystal vibrating pieces 3 on both the front and back surfaces of the quartz-crystal wafer W. In this embodiment, the etching-resistant mask has a structure corresponding to the outline of the quartz-crystal vibrating pieces 3, a frame portion 91 (see FIG. 5(b)) formed to surround multiple quartz-crystal vibrating pieces 3, and connection portions 92 (see FIG. 5(b)) connecting the frame portion 91 to each of the quartz-crystal vibrating pieces 3. After that, the quartz-crystal wafer W with the etching-resistant mask formed thereon is immersed for a predetermined period of time in an etching solution primarily composed of hydrofluoric acid. This process dissolves the portions of the quartz-crystal wafer W not covered by the etching-resistant mask, resulting in the rough outline of the quartz-crystal vibrating pieces 3, as shown in FIG. 5(b).

[0033] Next, the etching-resistant mask is removed from the quartz-crystal wafer W. At this time, only the portions of the etching-resistant mask corresponding to the excitation portion 3a and inclined portion 3c of the quartz-crystal vibrating piece 3 are removed, leaving behind the mesa portion 3b of the quartz-crystal vibrating piece 3 and the portions corresponding to the frame portion 91 and connecting portion 92 of the quartz-crystal wafer W. This makes it possible to form the inclined portion 3c located between the excitation portion 3a and the mesa portion 3b, and to ensure the strength of the frame portion 91 and connecting portion 92.

[0034] Next, the quartz-crystal wafer W with the etching-resistant mask partially removed is immersed again in an etching solution primarily composed of hydrofluoric acid for a predetermined time. The predetermined time is the time required for the thickness of the region where the excitation portion 3a of the quartz-crystal vibrating piece 3 is to be formed to a thickness that satisfies the required oscillation frequency specifications. Furthermore, due to the crystalline structure of the quartz-crystal wafer W, the amount of etching between the excitation portion 3a and the mesa portion 3b gradually increases toward the excitation portion 3a, resulting in the formation of a sloped portion 3c.

[0035] Next, the etching-resistant mask is removed from the quartz-crystal wafer W after the etching process, exposing the entire surface of the quartz-crystal wafer W. Next, another etching-resistant mask for forming the recesses 31 and 32 is formed using the same method as the removed etching-resistant mask. That is, a new etching-resistant mask is formed on the quartz-crystal wafer W to cover all areas of the quartz-crystal wafer W except for the areas that will become the recesses 31 and 32 of the quartz-crystal vibrating piece 3. The quartz-crystal wafer W with the new etching-resistant mask formed thereon is then immersed in an etching solution primarily containing hydrofluoric acid for a predetermined time. This process dissolves the areas of the quartz-crystal wafer W that are not covered by the new etching-resistant mask, forming the recesses 31 and 32 (i.e., the irregularities 30) on each of the quartz-crystal vibrating pieces 3, as shown in FIG. 5(c). Due to the crystalline structure of the quartz-crystal wafer W, the side surfaces of the recesses 31 and 32 on the mesa portion 3b side are inclined so as to be parallel to the inclined surface of the inclined portion 3c.

[0036] Next, after the above etching is completed, the etching-resistant mask is removed from the quartz-crystal wafer W, exposing the entire surface of the quartz-crystal wafer W. After that, a metal film for each electrode of the quartz-crystal vibrating piece 3 is formed on the entire surface (front and back surfaces) of the quartz-crystal wafer W using a well-known film-forming method. Next, the metal film is patterned into the shape of the electrodes using well-known photolithography and metal etching techniques, and each electrode is formed on the front and back surfaces of the quartz-crystal wafer W, as shown in Figures 3(b) and 4(b).

[0037] (Modification of the first embodiment) In the above embodiment, the second back surface electrode 70 is formed on the back surface of the quartz crystal vibrating piece 3 and the side surface electrode 80 is formed on the side surface to electrically connect the conductive adhesive 18 located on the back surface of the quartz crystal vibrating piece 3 to the first surface electrode 40 on the front surface of the quartz crystal vibrating piece 3, but the present invention is not limited to this structure. For example, a structure may be adopted in which the spreading of the conductive adhesive 18 is utilized to ensure electrical connection between the conductive adhesive 18 and the first surface electrode 40 without forming the second back surface electrode 70.

[0038] An example of such a structure will be described below with reference to FIGS. 6(a) to 6(c) as Variation 1 and FIGS. 7(a) to 7(c) as Variation 2. Here, FIG. 6(a) is a side view of a quartz crystal vibrating piece 3 according to Variation 1 of this embodiment, FIG. 6(b) is a front view of a quartz crystal vibrating piece 3 according to Variation 1 of this embodiment, and FIG. 6(c) is a back view of the quartz crystal vibrating piece 3 according to Variation 1 of this embodiment. Also, FIG. 7(a) is a side view of a quartz crystal vibrating piece 3 according to Variation 2 of this embodiment, FIG. 7(b) is a front view of a quartz crystal vibrating piece 3 according to Variation 2 of this embodiment, and FIG. 7(c) is a back view of the quartz crystal vibrating piece 3 according to Variation 2 of this embodiment. Note that the same components as those in the above embodiment are designated by the same reference numerals, and their description will be omitted.

[0039] 6(a) and 6(b), in Modification 1, the first surface electrode 40 is formed on the surface of the quartz crystal vibrating piece 3, as in the above embodiment, but the second surface electrode 50 is not formed. Also, as can be seen from FIGS. 6(a) and 6(c), the first back surface electrode 60 is formed on the back surface of the quartz crystal vibrating piece 3, as in the above embodiment, but the second back surface electrode 70 is not formed.

[0040] 6(a), a side electrode 82 having a width wider than the side electrode 80 of the above embodiment is formed on the side of the quartz-crystal vibrating piece 3, and the side electrode 82 is connected to the pad electrode 42 of the first surface electrode 40. That is, unlike the side electrode 80 of the above embodiment, the side electrode 82 is not connected to an electrode formed on the back surface of the quartz-crystal vibrating piece 3. In particular, the side electrode 82 is formed on the side of the inclined portion 3c of the quartz-crystal vibrating piece 3. The side electrode 82 is not limited to being formed spontaneously on the side of the quartz-crystal vibrating piece 3, but may be formed by wrapping around the plating when the first surface electrode 40 (particularly the pad electrode 42) is formed by plating.

[0041] Then, when the quartz crystal vibrating piece 3 is mounted with the conductive adhesive 18 applied in a predetermined position, the force pressing the quartz crystal vibrating piece 3 is controlled so that the conductive adhesive 18 is pushed out of the recesses 31 and 32 and spreads to the side surfaces of the quartz crystal vibrating piece 3. By spreading the conductive adhesive 18 to the side surfaces in this manner, the conductive adhesive 18 comes into contact with the side surface electrodes 82, ensuring electrical connection between the first surface electrodes 40 and the conductive adhesive 18.

[0042] In Modification 2, as can be seen from FIGS. 7(a) and 7(b), the first surface electrode 40' is composed of an excitation electrode 41, a pad electrode 42', and a connection electrode 43'. Unlike the pad electrode 42, the pad electrode 42' is formed on the surface side of the mesa portion 3b, not on the inclined portion 3c of the quartz-crystal vibrating piece 3. In particular, the pad electrode 42' is formed in a position displaced from the position facing the recess 32 toward the edge of the quartz-crystal vibrating piece 3, and has a smaller dimension than the pad electrode 42. The connection electrode 43' is longer than the connection electrode 43, and is formed from the excitation portion 3a to the inclined portion 3c of the quartz-crystal vibrating piece 3. As with Modification 1, the second surface electrode 50 is not formed.

[0043] On the other hand, as can be seen from FIGS. 7(a) and 7(c), the first back surface electrode 60' is composed of an excitation electrode 61, a pad electrode 62', and a connection electrode 63'. Unlike the pad electrode 62, the pad electrode 62' is formed on the back surface side of the mesa portion 3b, not on the inclined portion 3c of the quartz-crystal vibrating piece 3. In particular, the pad electrode 62' is formed at a position displaced toward the edge of the recess 31 and has a smaller dimension than the pad electrode 62. The connection electrode 63' is longer than the connection electrode 63 and is formed from the excitation portion 3a to the inclined portion 3c of the quartz-crystal vibrating piece 3. As with the first modification, the second back surface electrode 70 is not formed.

[0044] 7(a), a side electrode 82' having a width wider than the side electrode 80 of the above embodiment is formed on the side of the quartz-crystal vibrating piece 3, and the side electrode 82' is connected to the pad electrode 42' of the first surface electrode 40'. That is, unlike the side electrode 80 of the above embodiment, the side electrode 82' is not connected to an electrode formed on the back surface of the quartz-crystal vibrating piece 3. In particular, the side electrode 82' is formed on the side of the mesa portion 3b of the quartz-crystal vibrating piece 3. Like the side electrode 82, the side electrode 82' is not limited to being formed spontaneously on the side of the quartz-crystal vibrating piece 3, but may be formed by wrapping around the plating when the first surface electrode 40 (particularly the pad electrode 42') is formed by plating.

[0045] As in the first modification, when the quartz crystal vibrating piece 3 is mounted with the conductive adhesive 18 applied in a predetermined position, the force pressing the quartz crystal vibrating piece 3 is controlled so that the conductive adhesive 18 is pushed out of the recesses 31 and 32 and spreads to the side surfaces of the quartz crystal vibrating piece 3. By spreading the conductive adhesive 18 to the side surfaces in this manner, the conductive adhesive 18 comes into contact with the side surface electrode 82', thereby ensuring electrical connection between the first surface electrode 40' and the conductive adhesive 18.

[0046] In both of the modified examples, when the quartz crystal vibrating piece 3 is mounted in the package 2, the conductive adhesive 18 spreads beyond the recess and reaches the side of the quartz crystal vibrating piece 3. However, as with the above embodiment, this makes it easier to hold the quartz crystal vibrating piece 3 closer to its center of gravity, and increases the adhesive area in the recess. This further improves the mounting stability of the quartz crystal vibrating piece 3 and prevents the excitation part 3a, located on the opposite side from the adhesive fixation, from coming into contact with the package 2.

[0047] (Second embodiment) In the first embodiment, the unevenness 30 is formed by two recesses 31, 32 arranged side by side in the short-side direction in the inner region of the inclined portion 3c of the quartz crystal vibrating piece 3. However, this is not limited to this. For example, the unevenness structure may be formed by a single recess, or two recesses may be formed on the edge of the quartz crystal vibrating piece. Such a case will be described as the second embodiment and its modified example with reference to FIG. 8. Here, FIG. 8(a) is a rear view of the quartz crystal vibrating piece according to the second embodiment, and FIG. 8(b) is a rear view of the quartz crystal vibrating piece according to the modified example of the second embodiment. Note that the same components as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0048] 8(a), the quartz crystal vibrating piece 103 according to this embodiment has a single recess 133 that forms the unevenness 130. The recess 133 has a shape similar to two recesses 31 and 32 connected together, is formed in an inner region of the edge of the quartz crystal vibrating piece 103, and has a larger opening than each of the recesses 31 and 32. Two conductive adhesives 18 are positioned inside the recess 133, one of which is connected to the pad electrode 62 (i.e., the first back surface electrode 60), and the other is connected to the first front surface electrode 40 via the second back surface electrode 70.

[0049] Even with this type of quartz crystal vibrating piece 103, when the quartz crystal vibrating piece 103 is mounted in the package 2, the spread of the conductive adhesive 18 is controlled within the area of ​​the recess 133, making it easier to hold the quartz crystal vibrating piece 103 close to its center of gravity, as in the first embodiment, and increasing the adhesive area in the recess. This further improves the mounting stability of the quartz crystal vibrating piece 103 and prevents the excitation part 3a, located on the opposite side from the adhesive fixation, from coming into contact with the package 2.

[0050] (Modification of the second embodiment) As shown in FIG. 8B, the quartz-crystal vibrating piece 103′ according to the modified example of the second embodiment has a recess 134 formed at one end of the short side and a recess 135 formed at the other end of the short side, forming an unevenness 130′. That is, in the quartz-crystal vibrating piece 103′, the recesses 134 and 135 are formed at positions different from the recesses 31 and 32, and are formed on the edges of the quartz-crystal vibrating piece 103′. The conductive adhesive 18 is located inside each of the recesses 134 and 135, and the conductive adhesive 18 spreads from the recesses 134 and 135 to their exterior. The conductive adhesive 18 located in one of the recesses 134 constituting the unevenness 130′ is connected to the pad electrode 62 (i.e., the first back surface electrode 60), while the conductive adhesive 18 located in the other recess 135 is connected to the first front surface electrode 40 via the second back surface electrode 70.

[0051] Even in this modified example, when the quartz-crystal vibrating piece 103' is mounted in the package 2, the conductive adhesive 18 spreads outward from the edge of the quartz-crystal vibrating piece 103', but most of the adhesive is controlled within the area where the recesses 134 and 135 are formed. This makes it easier to hold the quartz-crystal vibrating piece close to its center of gravity, as in the first embodiment, and increases the adhesive area in the recesses 134 and 135. This further improves the mounting stability of the quartz-crystal vibrating piece 103', preventing the excitation portion 3a, located on the opposite side from the adhesive fixation, from coming into contact with the package 2.

[0052] The structure of the recesses 134, 135 according to this modification may be applied to the modification 1 or modification 2 of the first embodiment. In such a case, the conductive adhesive 18 can be easily spread on the side surface of the quartz crystal vibrating piece, making it easier to ensure electrical connection between the conductive adhesive 18 and the surface electrode.

[0053] (Third embodiment) In the first embodiment, the quartz crystal vibrating piece 3 and the IC chip 4 are mounted in the mounting space 2a of the package 2, but the quartz crystal vibrating piece 3 and the IC chip 4 may be mounted in different mounting spaces. This case will be described as the third embodiment with reference to Figure 9. Here, Figure 9 is an end view of a crystal oscillator 301 according to the third embodiment, similar to Figure 2(a).

[0054] 9, the crystal oscillator 301 includes a package 302, a crystal vibrating piece 303 mounted in a recessed first mounting space 302a of the package 302, an IC chip 304 mounted in a second mounting space 302b of the package 302, and a metal cover (lid) 305 for sealing the first mounting space 302a. Similar to the crystal oscillator 1 of the first embodiment, the crystal oscillator 301 is an electronic component that integrates the crystal vibrating piece 303, which is an example of a piezoelectric vibrating piece, and the IC chip 304, which is an oscillation circuit, in a single package, and is capable of generating a stable frequency and a regular reference signal.

[0055] The package 302 is a ceramic package formed by laminating multiple ceramics with desired metal patterns formed on their surfaces. Specifically, the package 302 has a laminated structure in which a first outer frame wall 311, which is a bank portion with an opening of a predetermined size, a second outer frame wall 312, which has an opening smaller than that of the first outer frame wall 311, and a rectangular bottom plate 313 are laminated. The package 302 has a so-called H-shaped structure in which the first outer frame wall 311 is laminated on the front surface 313a of the bottom plate 313 and the second outer frame wall 312 is laminated on the back surface 313b of the bottom plate 313. This laminated structure allows the package 302 to mount the quartz crystal vibrating piece 303 and the IC chip 304 in separate mounting spaces.

[0056] A sealing conductor pattern 315 is formed on the exposed surface (the surface located on the upper vertical side) of first outer frame wall 311 of package 302. The planar shape of conductor pattern 315 is frame-shaped, similar to first outer frame wall 311. Cover 305 is joined onto conductor pattern 315 by known metal joining. This hermetically seals first mounting space 302a of the package, and first mounting space 302a is sealed using a vacuum or a gas such as nitrogen.

[0057] Two crystal vibrating piece mounting terminals (only crystal vibrating piece mounting terminal 316 is shown in FIG. 9) are formed on surface 312a of bottom plate 313 of package 302. Crystal vibrating piece 303 is mounted on each of the crystal vibrating piece mounting terminals via conductive adhesive 318. Each of the crystal vibrating piece mounting terminals is electrically connected to an external connection terminal via connection wiring (not shown) provided inside package 302.

[0058] A plurality of IC terminals 341 are formed on the back surface 312b of the bottom plate 313 of the package 302. A conductive adhesive 351 is applied to each of the IC terminals 341, and the IC chip 304 is mounted via these conductive adhesives 351. That is, in the crystal oscillator 301, the flip-chip type IC chip 304 is mounted by flip-chip bonding. Each of the IC terminals 341 is electrically connected to an external connection terminal via connection wiring (not shown) provided inside the package 302.

[0059] Four external connection terminals (only external connection terminals 320c and 320d are shown in FIG. 9) are formed on the back surface of second outer frame wall 312 of package 302. Each of these external connection terminals is connected to either a crystal vibrating piece mounting terminal or an IC terminal 341 via connection wiring (not shown) provided inside package 302.

[0060] The quartz crystal vibrating piece 303 according to this embodiment has the same structure as the quartz crystal vibrating piece 3 according to the first embodiment, and the mounting method using the conductive adhesive 318 is also the same. Therefore, the structure and mounting method of the quartz crystal vibrating piece 303 will not be described here.

[0061] In this embodiment, when the quartz crystal vibrating piece 303 is mounted in the package 302, this type of holding of the quartz crystal vibrating piece 303 ensures adhesion near the center of gravity of the quartz crystal vibrating piece 303, preventing the excitation portion from sagging. Furthermore, compared to a case where the quartz crystal vibrating piece 303 does not have any irregularities, the recesses that make up the irregularities act as guides to control the spread of the conductive adhesive 318, making it easier to hold the quartz crystal vibrating piece 303 near the center of gravity and increasing the adhesive area in the recesses. This further improves the mounting stability of the quartz crystal vibrating piece 303 and prevents the excitation portion, located on the opposite side of the adhesive fixation, from coming into contact with the package 302.

[0062] (Fourth embodiment) In the first embodiment, the crystal oscillator 1 having the IC chip 4 has been described as an example of a piezoelectric device, but a crystal resonator without an IC chip 4 may also be applied to the piezoelectric device according to the present disclosure. Such a case will be described as the fourth embodiment with reference to FIG. 10. Here, FIG. 10 is an end view of a crystal resonator 401 according to the fourth embodiment, similar to FIG. 2(a).

[0063] 10, a quartz crystal unit 401, which is an example of a piezoelectric device, includes a quartz crystal unit package 402 (hereinafter simply referred to as package 402), a quartz crystal vibrating piece 403 mounted in a recessed mounting space 402a of the package 402, and a metal cover (lid) 405 for sealing the mounting space 402a. The package 402 is a ceramic package formed by laminating multiple ceramics on the surface of which a desired metal pattern is formed. Specifically, the package 402 has a laminated structure in which a frame wall 411, which is a bank portion with an opening of a predetermined dimension, and a rectangular bottom plate 413 are laminated.

[0064] A sealing conductor pattern is formed on the upper surface of frame wall 411 of package 402. The planar shape of this conductor pattern is frame-shaped, just like frame wall 411. Cover 405 is bonded onto this conductor pattern by known metal bonding. This seals mounting space 402a of the package, and mounting space 402a is sealed using a vacuum or a gas such as nitrogen.

[0065] Two crystal vibrating piece mounting terminals (only crystal vibrating piece mounting terminal 416 is shown in FIG. 10) are formed on the surface of bottom plate 413 of package 402. Here, crystal vibrating piece 403 is mounted on each of the crystal vibrating piece mounting terminals via conductive adhesive 418. Each of the crystal vibrating piece mounting terminals is electrically connected to an external connection terminal via connection wiring (not shown) provided inside package 402. Meanwhile, four external connection terminals 422 are formed on the back surface of bottom plate 413 of package 402.

[0066] The quartz crystal vibrating piece 403 according to this embodiment has the same structure as the quartz crystal vibrating piece 3 according to the first embodiment, and the mounting method using the conductive adhesive 418 is also the same. Therefore, the structure and mounting method of the quartz crystal vibrating piece 403 will not be described here.

[0067] In this embodiment, when the quartz crystal vibrating piece 403 is mounted in the package 402, this type of holding of the quartz crystal vibrating piece 403 ensures adhesion near the center of gravity of the quartz crystal vibrating piece 403, preventing the excitation portion from sagging. Furthermore, compared to a case where the quartz crystal vibrating piece 403 does not have any irregularities, the recesses that make up the irregularities act as guides to control the spread of the conductive adhesive 418, making it easier to hold the quartz crystal vibrating piece 403 near the center of gravity and increasing the adhesive area in the recesses. This further improves the mounting stability of the quartz crystal vibrating piece 403 and prevents the excitation portion, located on the opposite side of the adhesive fixation, from coming into contact with the package 402.

[0068] (Embodiments of the present disclosure) A first embodiment of the present disclosure is a piezoelectric device comprising: a package including a bottom plate that is rectangular in plan view, a bank portion provided along the edge of the bottom plate, and an adhesive pad provided on one end side of the long side of an inner region surrounded by the bank portion; a piezoelectric vibrating piece that is rectangular in plan view and includes a flat excitation portion, a mesa portion that is thicker than the excitation portion, and an inclined portion that is located between the excitation portion and the mesa portion and whose thickness gradually increases from the excitation portion toward the mesa portion; and an adhesive that adheres the inclined portion of the piezoelectric vibrating piece to the adhesive pad at a position where the mesa portion and the inclined portion face the adhesive pad, wherein the piezoelectric vibrating piece has an unevenness formed from the inclined portion into the mesa portion, and the adhesive is located in the recess.

[0069] The unevenness of the piezoelectric vibrating piece prevents the adhesive from spreading toward the mesa portion, and the piezoelectric vibrating piece is held in place at the central portion of the piezoelectric vibrating piece where the inclined portion is located. This allows the piezoelectric vibrating piece to be bonded closer to its center of gravity, preventing the excitation portion from dropping compared to when it is held by the flat back surface of the mesa portion. Furthermore, the unevenness acts as a guide to control the spread of the adhesive, making it easier to hold the piezoelectric vibrating piece closer to its center of gravity and increasing the bonding area of ​​the unevenness. This further improves the stability of the piezoelectric vibrating piece's mounting and prevents the excitation portion, located on the opposite side of the adhesive fixation, from coming into contact with the package.

[0070] In a second embodiment of the present disclosure, a back surface electrode is formed on the back surface of the piezoelectric vibrating reed, which is the surface facing the package, from the excitation portion to the inclined portion, and the adhesive is in contact with the inclined portion side of the back surface electrode, thereby ensuring electrical contact between the back surface electrode formed on the back surface of the piezoelectric vibrating reed and the adhesive, and enabling power to be supplied to the back surface electrode.

[0071] In a third embodiment of the present disclosure, in the first or second embodiment, the piezoelectric vibrating piece has two recesses arranged side by side in the short side direction, which serve as guides to control the spread of adhesive, making it easier to hold the piezoelectric vibrating piece close to its center of gravity and increasing the adhesive area in the recesses.

[0072] A fourth embodiment of the present disclosure is similar to the third embodiment in that the adhesive located in one of the two recesses is in contact with the back electrode, and the adhesive located in the other recess is electrically connected to the front electrode formed on the surface of the piezoelectric vibrating reed, thereby ensuring electrical connection between each adhesive and the electrodes on the front and back surfaces, and enabling power supply to the front and back surfaces of the piezoelectric vibrating reed.

[0073] A fifth embodiment of the present disclosure is the third embodiment, wherein the two recesses are formed in an area inside the edge of the piezoelectric vibrating piece, thereby preventing the adhesive from spreading and positioning the adhesive in the required area on the back surface of the piezoelectric vibrating piece.

[0074] A sixth embodiment of the present disclosure is the third embodiment, in which the adhesive is formed on the edge of the piezoelectric vibrating piece, thereby preventing the adhesive from spreading and allowing the adhesive to be positioned in the required area on the back surface of the piezoelectric vibrating piece.

[0075] In a seventh embodiment of the present disclosure, in the first or second embodiment, the piezoelectric vibrating piece has one recess formed in an area inside the edge, which prevents the adhesive from spreading and allows the adhesive to be positioned in the required area on the back surface of the piezoelectric vibrating piece.

[0076] In an eighth embodiment of the present disclosure, in the fourth embodiment, the adhesive located in the other recess is connected to the surface electrode via a side electrode formed on the side of the piezoelectric vibrating piece, thereby ensuring electrical contact between the adhesive and the surface electrode formed on the surface of the piezoelectric vibrating piece, and enabling power to be supplied to the surface electrode.

[0077] A ninth embodiment of the present disclosure is the eighth embodiment, wherein the side electrode is formed on the side surface of the inclined portion or the mesa portion, thereby making it easier to ensure electrical connection between the adhesive and the electrode by utilizing the spreading of the adhesive.

[0078] A tenth embodiment of the present disclosure provides a piezoelectric vibrating reed characterized by having a flat excitation portion, a mesa portion having a thickness greater than that of the excitation portion, an inclined portion located between the excitation portion and the mesa portion and gradually increasing in thickness from the excitation portion toward the mesa portion, and a concave / convex portion formed from the inclined portion to the inside of the mesa portion, where an adhesive is positioned during mounting. The inclined portion of the piezoelectric vibrating reed prevents the adhesive from spreading toward the mesa portion, and the piezoelectric vibrating reed is held in place at the central portion of the piezoelectric vibrating reed where the inclined portion is located. This allows the piezoelectric vibrating reed to be bonded closer to its center of gravity, preventing the excitation portion from dropping compared to when held by the flat back surface of the mesa portion. Furthermore, the inclined portion acts as a guide to control the spread of the adhesive, making it easier to hold the piezoelectric vibrating reed closer to its center of gravity, and increasing the bonding area of ​​the inclined portion. This further improves the stability of the piezoelectric vibrating reed and prevents the excitation portion, located on the opposite side of the adhesive fixing portion, from contacting the package.

[0079] A ninth embodiment of the present disclosure is a piezoelectric wafer including a plurality of piezoelectric vibrating pieces according to the tenth embodiment, a frame to which the plurality of piezoelectric vibrating pieces are connected, and connection parts that connect each of the piezoelectric vibrating pieces to the frame, thereby enabling the plurality of piezoelectric vibrating pieces to be formed and supplied simultaneously. [Explanation of symbols]

[0080] 1. Crystal oscillator 2 Crystal oscillator package (package) 2a Mounting space 3 Crystal vibrating piece 3a Excitation part 3b Mesa section 3c Slope 4 IC chip 5 Cover (lid) 11 Outer frame wall (bank section) 12 Inner frame wall 13 Bottom plate 16,17 Crystal unit mounting terminals (adhesive pads) 18 Conductive adhesive 30 Unevenness 31,32 Recess 40 1st surface electrode 41 Excitation electrode 42 Pad electrode 43 Connecting electrode 50 2nd surface electrode 60 First rear surface electrode 61 Excitation electrode 62 Pad electrode 63 Connection electrode 70 Second rear electrode 80,82 side electrode

Claims

1. a package including a bottom plate having a rectangular shape in a plan view, a bank portion provided along an edge of the bottom plate, and an adhesive pad provided on one end side in a long side direction of an inner region surrounded by the bank portion; a piezoelectric vibrating piece that is rectangular in plan view and includes a flat excitation portion, a mesa portion that is thicker than the excitation portion, and an inclined portion that is located between the excitation portion and the mesa portion and whose thickness gradually increases from the excitation portion toward the mesa portion; an adhesive that bonds the inclined portion of the piezoelectric vibrating piece to the bonding pad at a position where the mesa portion and the inclined portion face the bonding pad, The piezoelectric vibrating piece has a concave-convex shape formed from the inclined portion to the inside of the mesa portion, and the adhesive is located in the concave portion.

2. a back surface electrode is formed on the back surface of the piezoelectric vibrating piece, the back surface being the surface on the package side, from the excitation portion to the inclined portion; The piezoelectric device according to claim 1 , wherein the adhesive is in contact with the inclined portion of the back electrode.

3. 3. The piezoelectric device according to claim 2, wherein the piezoelectric vibrating piece has two recesses arranged side by side in the short-side direction.

4. The piezoelectric device of claim 3, characterized in that the adhesive located in one of the two recesses is in contact with the back electrode, and the adhesive located in the other recess is electrically connected to a surface electrode formed on the surface of the piezoelectric vibrating piece.

5. The piezoelectric device according to claim 3 , wherein the two recesses are formed in an area inside the edge of the piezoelectric vibrating piece.

6. The piezoelectric device according to claim 3 , wherein the two recesses are formed on the edges of the piezoelectric vibrating piece.

7. 3. The piezoelectric device according to claim 2, wherein the piezoelectric vibrating piece has one recess formed in an area inside the edge.

8. The piezoelectric device according to claim 4 , wherein the adhesive located in the other recess is connected to the surface electrode via a side electrode formed on a side surface of the piezoelectric vibrating piece.

9. 9. The piezoelectric device according to claim 8, wherein the side electrode is formed on a side surface of the inclined portion or the mesa portion.

10. a flat excitation part; a mesa portion having a thickness greater than that of the excitation portion; an inclined portion located between the excitation portion and the mesa portion, the thickness of which gradually increases from the excitation portion toward the mesa portion; and a concave-convex portion formed from the inclined portion to the inside of the mesa portion, on which an adhesive is placed when the piezoelectric vibrating piece is mounted.

11. A plurality of piezoelectric vibrating reeds according to claim 10; a frame portion to which the piezoelectric vibrating piece is connected; and a connecting portion that connects each of the piezoelectric vibrating pieces to the frame portion.

Images