Piezoelectric vibration device

Abstract

The present invention makes it possible to reduce the effects, on a vibration part of a piezoelectric diaphragm, of stress such caused by, for example, thermal contraction of an adhesive, such as tensile stress or compressive stress between the adhesive.　Two piezoelectric vibrator mounting pads 63a, 63b of a base 6 and two piezoelectric vibrator connection terminals of a lower plate 2 of a piezoelectric vibrator Pv are respectively joined by an adhesive 65. The adhesive 65 is disposed at two spots positioned to overlap with a vibration part 33, a cutout part 36, and an outer frame part 34 of the piezoelectric diaphragm 3 in plan view. Thus, it is possible to reduce the effects, on the vibration part 33 of the piezoelectric diaphragm, of stress caused by compressive stress or tensile stress between the adhesive 65.

Description

Piezoelectric vibration device

[0001] The present invention relates to a piezoelectric vibration device.

[0002] Conventionally, there are piezoelectric vibration devices described in Patent Documents 1 and 2 in which a piezoelectric vibrator is hermetically sealed inside a package. This type of piezoelectric vibration device includes a package formed by laminating, for example, ceramic substrates having a substantially rectangular shape in plan view and having external connection terminals for connection to an external circuit on the outer bottom surface, a piezoelectric vibrator having a substantially rectangular shape in plan view with only one end side joined inside the package, and a lid that closes the upper surface of the package and hermetically seals the inside of the package. At this time, the other end opposite to one end of the piezoelectric vibrator is a free end that can be displaced.

[0003] The piezoelectric vibrators described in Patent Documents 1 and 2 are of a double-sealing type in which the upper and lower sides of the piezoelectric vibration plate are hermetically sealed with two sealing members, and further, the piezoelectric vibrator is hermetically sealed inside a package. The piezoelectric vibration plate has a structure including an outer frame portion having a substantially rectangular shape in plan view, a vibration portion having a pair of excitation electrodes, a cutout portion between the outer frame portion and the vibration portion, and a holding portion that connects and holds the vibration portion and the outer frame portion. At this time, the holding portion that connects the vibration portion and the outer frame portion is on the other end side, which is the free end of the piezoelectric vibrator, and is located on the side opposite to one end of the piezoelectric vibrator joined to the package by an adhesive.

[0004] By the way, when joining to a package at two locations on one end side of a piezoelectric vibrator as in this type of piezoelectric vibration device, depending on the joining position of the adhesive, the vibration portion connected to the outer frame portion by the holding portion of the piezoelectric vibrator is affected by the tensile stress and compressive stress between the adhesives. The inventor of the present application has verified that there are joining positions that are easily affected and joining positions that are hardly affected. Specifically, in a piezoelectric vibrator having a substantially rectangular shape in plan view, the susceptibility to stress influence also differs depending on the relationship with the direction in which the holding portion extends. When the two joining positions are arranged perpendicular to the direction in which the holding portion extends, they are easily affected by stress, and when the two joining positions are arranged parallel to the direction in which the holding portion extends, they are hardly affected by stress. The inventor of the present application has also verified that when the two adhesives overlap a part of the outer frame portion and the cutout portion of the piezoelectric vibration plate in plan view, the influence of stress can be alleviated.

[0005] Re-Table 2018 / 092572 Publication Patent No. 7060053 Publication

[0006] However, in the case of the piezoelectric vibration devices described in Patent Documents 1 and 2, the two joints are made at two points, including the corner furthest from the holding portion, and are aligned perpendicular to the direction in which the holding portion extends. As a result, the adhesives at these two points do not overlap the outer frame portion and part of the cutout portion of the piezoelectric diaphragm in a plan view (see Figures 1, 5, and 6 of Patent Documents 1 and 2). Therefore, the vibrating portion of the piezoelectric diaphragm may be affected by tensile and compressive stresses between the adhesives, which could hinder the improvement of the accuracy of the vibration characteristics.

[0007] This invention has been made in view of the above-mentioned problems, and aims to reduce the influence of stresses such as tensile stress and compressive stress between adhesives, as well as stresses due to thermal shrinkage of adhesives, on the vibrating part of a piezoelectric diaphragm.

[0008] To achieve the above objective, the piezoelectric vibration device according to the present invention comprises a base and a piezoelectric vibrator mounted on the base, wherein the base is made of an insulating substrate that is substantially rectangular in plan view, has an external connection terminal on the outer bottom surface of the insulating substrate, has a mounting portion for mounting the piezoelectric vibrator on the surface opposite to the outer bottom surface of the insulating substrate, and has two pad portions provided on the mounting portion for joining the piezoelectric vibrator to the insulating substrate, the piezoelectric vibrator mounted on the mounting portion is hermetically sealed by a cover, the piezoelectric vibrator has a laminated structure of a piezoelectric diaphragm and a lower plate on which the piezoelectric diaphragm is mounted, the piezoelectric diaphragm has an outer frame portion that is substantially rectangular in plan view to which the lower plate is joined, and a substantially rectangular outer frame portion that is substantially rectangular in plan view to which a pair of excitation electrodes are formed The piezoelectric vibrator comprises a vibrating portion in the shape of a box, a cutout portion between the outer frame portion and the vibrating portion, and a holding portion connecting the vibrating portion and the outer frame portion. The lower plate is made of a substrate having a substantially rectangular shape in plan view and has at least two connection terminals on its bottom surface that are connected to the pair of excitation electrodes. The piezoelectric vibrator is mounted on the mounting portion with two joints at one end, where the two pad portions of the base and the two connection terminals of the piezoelectric vibrator are joined by adhesive, and the other end opposite to the two joints forms a free end. At least one of the adhesives that joins the two pad portions and the two connection terminals is positioned to overlap a portion of the outer frame portion and the cutout portion of the piezoelectric vibrator.

[0009] In this configuration, the two pad portions of the base and the two connection terminals of the piezoelectric vibrator are joined together with adhesive, and at least one of the adhesives is positioned to overlap the outer frame portion and part of the cutout portion of the piezoelectric vibrator. As a result, the stress caused by tensile stress, compressive stress, and thermal contraction of the adhesive between the adhesives can be reduced in effect on the vibrating portion of the piezoelectric vibrator by the spatial region formed by the cutout portion of the piezoelectric vibrator located above the lower plate.

[0010] Furthermore, since the cutout portion of the piezoelectric diaphragm is located closer to the center than the outer frame portion, the distance between the two adhesive points that join the two pad portions of the base and the two connection terminals of the piezoelectric vibrator can be shortened, thereby suppressing displacement due to thermal shrinkage of the adhesive, such as tensile and compressive stress between the adhesive points.

[0011] Furthermore, since the adhesive is superimposed across the outer frame of the piezoelectric diaphragm, which has high mechanical strength to which the lower plate is joined, high bonding strength can be ensured for the piezoelectric vibrator as a whole. In addition, the bonding strength can be improved while suppressing the transmission of restraining forces due to the thermal shrinkage of the adhesive to the vibrating part of the piezoelectric vibrator, thereby increasing the stability and reliability of the piezoelectric vibrator joint.

[0012] Furthermore, the piezoelectric vibrator may be further provided with an upper plate that is superimposed on the side of the piezoelectric diaphragm opposite to the mounting surface on the lower plate, and together with the lower plate, airtightly seals the vibrating portion of the piezoelectric diaphragm.

[0013] This configuration provides a piezoelectric vibration device with a double-sealed structure, having a three-layer laminated structure consisting of an upper plate, a piezoelectric diaphragm, and a lower plate, and further hermetically sealing the piezoelectric diaphragm inside the base. This double sealing makes it less susceptible to changes in the external environment, allowing for a smaller piezoelectric vibration device with more stable characteristics.

[0014] Furthermore, the outer frame portion has an inner wall that is substantially rectangular in plan view, and the adhesive that joins the two pad portions of the base and the two connection terminals of the piezoelectric vibrator is preferably positioned at the corner of the inner wall of the outer frame portion, overlapping two adjacent sides of the rectangle of the inner wall.

[0015] With this configuration, the adhesive that joins the two pad portions of the base to the two connection terminals of the piezoelectric vibrator is superimposed on the corners of the inner wall of the outer frame portion, which are adjacent sides of the inner wall rectangle, thus distributing the adhesive stress between the piezoelectric vibrator and the base.

[0016] Furthermore, the two joints formed by the adhesive should be located away from the holding portion.

[0017] With this configuration, since the two bonding points using adhesive are located far from the holder of the piezoelectric vibrator, the effects of stress and strain from the adhesive are less likely to be transmitted to the vibrating part of the piezoelectric vibrator, thus maintaining high stability and reliability in the bonding of the piezoelectric vibrator.

[0018] Furthermore, the adhesives used to join the two pad portions of the base to the two connection terminals of the piezoelectric vibrator are preferably arranged parallel to the direction in which the holding portion extends.

[0019] With this configuration, the two adhesives are aligned parallel to the direction of extension of the piezoelectric vibrator's holding portion. This reduces the transmission of stress and strain from the adhesive to the vibrating portion of the piezoelectric vibrator, thus ensuring high stability and reliability in the bonding of the piezoelectric vibrator.

[0020] Furthermore, the adhesive may be made of silicone resin. With this configuration, the stress and strain transmitted to the vibrating part of the piezoelectric vibrator by the adhesive can be minimized because the silicone resin used in the adhesive exhibits less stress and strain compared to epoxy resin. In particular, silicone resin adhesives have improved cushioning properties and enhanced impact resistance.

[0021] According to the present invention, it is possible to reduce the influence of stresses caused by thermal shrinkage of adhesives, such as tensile stress and compressive stress between adhesives, on the vibrating part of a piezoelectric diaphragm.

[0022] This is a cross-sectional view of a piezoelectric vibration device according to the first embodiment of the present invention. This is a plan view of the piezoelectric vibration device of Figure 1 with the cover removed. This is a plan view of the piezoelectric vibration device of Figure 1 with the cover, piezoelectric vibrator, and electronic components removed. This is a plan view of the top plate of the piezoelectric vibration device of Figure 1. This is a bottom view of the top plate of the piezoelectric vibration device of Figure 1. This is a plan view of the piezoelectric diaphragm of the piezoelectric vibration device of Figure 1. This is a bottom view of the piezoelectric diaphragm of the piezoelectric vibration device of Figure 1. This is a cross-sectional view of the piezoelectric diaphragm of the piezoelectric diaphragm of Figure 6 along the line L-L. This is a plan view of the bottom plate of the piezoelectric vibration device of Figure 1. This is a bottom view of the bottom plate of the piezoelectric vibration device of Figure 1. This is a plan view of the piezoelectric vibration device of Figure 1 with the cover removed. This is a bottom view of the bottom plate of the piezoelectric vibration device of Figure 1 according to the second embodiment of the present invention. This is a bottom view of the bottom plate of the piezoelectric vibration device of Figure 11. This is a cross-sectional view of a piezoelectric vibration device according to the third embodiment of the present invention. This is a plan view of the piezoelectric vibration device of the fourth embodiment of the present invention with the cover removed. This is a plan view of the piezoelectric vibration device of the fifth embodiment of the present invention with the cover removed. This is a plan view of the piezoelectric vibration device of the sixth embodiment of the present invention with the cover removed. This is a cross-sectional view of a piezoelectric vibration device according to the seventh embodiment of the present invention. This is a cross-sectional view of a piezoelectric vibration device according to the eighth embodiment of the present invention.

[0023] <First Embodiment> A piezoelectric vibration device according to the first embodiment of the present invention will be described with reference to Figures 1 to 10.

[0024] (Configuration) As shown in Figure 1, the piezoelectric vibration device 1 in the first embodiment comprises a piezoelectric vibrator Pv consisting of a substantially rectangular lower plate 2 having at least two connection terminals on its lower surface, a piezoelectric diaphragm 3, and an upper plate 4, an integrated circuit element (hereinafter referred to as IC) 5 which is an electronic component, and a ceramic base 6 that hermetically seals the lower plate 2, the piezoelectric vibrator Pv mounted on the lower plate 2, and the IC 5. Here, the piezoelectric vibrator Pv has a three-layer laminated structure in which the lower plate 2, the piezoelectric diaphragm 3 mounted on the upper surface opposite to the lower surface of the lower plate 2, and the upper plate 4 superimposed on the upper surface of the piezoelectric diaphragm 3 are laminated. A lid 7 made of a metal plate is seam-welded to the upper surface of the base 6 by a substantially rectangular metal member 8, thereby sealing the base 6.

[0025] As shown in Figure 1, the base 6 is formed by stacking multiple ceramic plates and has an overall rectangular parallelepiped shape with an open top surface. Inside, a recess 61 is formed off-center to one side (the right side in Figure 1), and a stepped portion 62 is formed above the inner bottom surface 61a of the recess 61, protruding to approximately the center in a plan view. The stepped portion 62 is provided with two mounting pads that are electrically connected to the two piezoelectric vibrator connection terminals of the lower plate 2, which will be described later, and the IC 5 is positioned on the inner bottom surface 61a of the recess 61.

[0026] Figure 2 shows the base 6 without the cover 7, and Figure 3 is a plan view showing the state before the piezoelectric vibrator Pv and IC 5 are housed in the base 6. As shown in Figure 2, the stepped portion 62 in the base 6, which is the mounting portion for the piezoelectric vibrator Pv, is provided with a pair of piezoelectric vibrator mounting pads 63a and 63b that are electrically connected to the two piezoelectric vibrator connection terminals 23 and 21 (see Figure 10) on the lower plate 2, respectively. Furthermore, the recess 61 is provided with first to sixth IC mounting pads 64a, 64b, 64c, 64d, 64e, and 64f. The outer bottom surface 6a of the base 6 is provided with a plurality of external connection terminals OUT. Here, the piezoelectric vibrator mounting pads 63a and 63b correspond to the "pad portion" in the present invention.

[0027] These piezoelectric vibrator mounting pads 63a and 63b are electrically connected to the piezoelectric vibrator connection terminals 23 and 21, respectively, by an adhesive 65 made of silicone resin, for example, a conductive adhesive. The adhesive 65 may also be made of epoxy resin, and is not limited to a conductive adhesive; it may also be a combination of an insulating adhesive and a wire.

[0028] The piezoelectric vibrator Pv comprises a lower plate 2, a piezoelectric diaphragm 3 having a vibrating section (not shown) including a pair of excitation electrodes and joined to the lower plate 2 by being superimposed on it, and an upper plate 4 superimposed on the side of the piezoelectric diaphragm 3 opposite to the mounting surface on the lower plate 2, and together with the lower plate 2, hermetically seals the vibrating section of the piezoelectric diaphragm 3. This piezoelectric vibrator Pv has a sandwich structure formed by joining the piezoelectric diaphragm 3, the upper plate 4, and the lower plate 2. A space is formed inside, and the vibrating section of the piezoelectric diaphragm 3 is hermetically sealed in this internal space, and the upper surface of the base 6 is sealed by the lid 7, thus providing double sealing.

[0029] As shown in Figures 6 and 7, the piezoelectric diaphragm 3 is a roughly rectangular parallelepiped quartz substrate 31, with the first main surface 3a and the second main surface 3b formed as flat, smooth surfaces (mirror-finished). An AT-cut quartz plate that performs thickness-sliding vibration is used as the piezoelectric diaphragm 3. In the piezoelectric diaphragm 3 shown in Figures 6 and 7, the first and second main surfaces 3a and 3b of the piezoelectric diaphragm 3 are the XZ' plane.

[0030] In this XZ' plane, the direction parallel to the shorter side of the rectangle of the piezoelectric diaphragm 3 is defined as the X-axis direction, and the direction parallel to the longer side of the rectangle of the piezoelectric diaphragm 3 is defined as the Z'-axis direction. AT cutting is a processing method in which artificial quartz is cut at an angle of 35°15′ around the X-axis with respect to the Z-axis, one of the three crystal axes of artificial quartz: the electrical axis (X-axis), the mechanical axis (Y-axis), and the optical axis (Z-axis). In an AT-cut quartz plate, the X-axis coincides with the crystal axis of the quartz. The Y'-axis and Z'-axis coincide with axes that are 35°15′ inclined from the Y-axis and Z-axis of the quartz crystal axis, respectively. The Y'-axis and Z'-axis directions correspond to the cutting direction when cutting the AT-cut quartz plate. Note that the piezoelectric diaphragm 3 may be an SC-cut quartz plate or a tuning fork type vibrator, not limited to the AT-cut quartz plate described above.

[0031] The piezoelectric diaphragm 3 has a substantially rectangular vibrating section 33 with a pair of excitation electrodes, a first excitation electrode 32a and a second excitation electrode 32b, formed on a first main surface 3a and a second main surface 3b, respectively; an outer frame section 34 having an inner wall that is rectangular in plan view and surrounds the outer wall of the vibrating section 33; a holding section 35 that holds the vibrating section 33 by connecting the outer wall of the vibrating section 33 and the inner wall of the outer frame section 34; and a cutout section 36 formed between the vibrating section 33 and the outer frame section 34 by cutting out the piezoelectric diaphragm 3 in the thickness direction. In other words, the piezoelectric diaphragm 3 has a configuration in which the vibrating section 33, the outer frame section 34 and the holding section 35 are integrally provided.

[0032] The holding portion 35 is provided at only one location between the vibrating portion 33 and the outer frame portion 34. Furthermore, as shown in Figure 8, which represents the cross-section along the line L-L in Figure 6, the vibrating portion 33 and the holding portion 35 are formed thinner than the outer frame portion 34. Due to this difference in thickness between the outer frame portion 34 and the holding portion 35, the natural frequencies of the piezoelectric vibrations of the outer frame portion 34 and the holding portion 35 are different, and the propagation of vibrations excited in the vibrating portion 33 is suppressed. In addition, when the upper plate 4 and the lower plate 2 are joined to the piezoelectric vibrating plate 3, a gap is formed between the vibrating portion 33 and the upper plate 4 and the lower plate 2 on the inner side of the inner circumferential wall of the outer frame portion 34, and this gap is sealed. Alternatively, the outer frame portion 34 of the piezoelectric diaphragm 3 may be made thicker than the vibrating portion 33 and the holding portion 35, and a gap may be formed by joining the flat upper plate 4 and the lower plate 2. In other words, the outer frame portion 34 may be made the same thickness as the vibrating portion 33 and the holding portion 35, and a gap may be formed by creating recesses in the upper plate 4 and the lower plate 2 and joining them together.

[0033] The holding portion 35 is formed parallel to the Z' axis, extending from only one corner of the vibrating portion 33 located in the +X and +Z' directions to the outer frame portion 34 in the +Z' direction. In this way, since the holding portion 35 is provided at the corner of the outer circumference of the vibrating portion 33 where the displacement of piezoelectric vibration is relatively small, it is possible to suppress leakage of piezoelectric vibration to the outer frame portion 34 through the holding portion 35 compared to when the holding portion 35 is provided at a part other than the corner (the center of the side), and the vibrating portion 33 can be vibrated piezoelectrically more efficiently. Furthermore, compared to when two or more holding portions 35 are provided, the stress acting on the vibrating portion 33 can be reduced, and the frequency shift of piezoelectric vibration caused by such stress can be reduced, thereby improving the stability of piezoelectric vibration.

[0034] The first excitation electrode 32a is provided on the first main surface 3a side of the vibrating section 33, and the second excitation electrode 32b is provided on the second main surface 3b side of the vibrating section 33. The first excitation electrode 32a and the second excitation electrode 32b are connected to the first and second excitation electrodes 32a and 32b, respectively, by first lead wiring 37a and second lead wiring 37b for connecting these first and second excitation electrodes 32a and 32b to external electrode terminals. The first lead wiring 37a is drawn out from the first excitation electrode 32a and connected via the holding section 35 to a roughly rectangular connecting joint pattern 381 that is elongated in the X-axis direction and formed on the +Z' side of the outer frame section 34. The second lead wiring 37b is drawn out from the second excitation electrode 32b and connected via the holding section 35 to a roughly circular connecting joint pattern 382 that is formed on the outer frame section 34 in the +X direction and the +Z' direction. As described above, the first lead wire 37a is formed on the first main surface 3a side of the holding portion 35, and the second lead wire 37b is formed on the second main surface 3b side of the holding portion 35.

[0035] Furthermore, on the -Z' side of the first main surface 3a and the second main surface 3b of the outer frame portion 34 of the piezoelectric diaphragm 3, approximately rectangular connecting joint patterns 383 and 384, which are elongated in the X-axis direction, are formed, respectively. On the +X or +Z' side of the first main surface 3a of the outer frame portion 34 of the piezoelectric diaphragm 3, approximately crescent-shaped connecting joint pattern 385 is formed. Additionally, on the opposite side of the connecting joint pattern 384 on the second main surface 3b of the outer frame portion 34 of the piezoelectric diaphragm 3, approximately rectangular connecting joint pattern 386, which is elongated in the X-axis direction, is formed.

[0036] The first main surface 3a and the second main surface 3b of the piezoelectric diaphragm 3 are provided with vibration-side sealing portions for joining the piezoelectric diaphragm 3 to the upper plate 4 and the lower plate 2, respectively. The vibration-side sealing portion of the first main surface 3a has a vibration-side first joining pattern 387a formed for joining to the upper plate 4. The vibration-side sealing portion of the second main surface 3b has a vibration-side second joining pattern 387b formed for joining to the lower plate 2. The vibration-side first joining pattern 387a and the vibration-side second joining pattern 387b are provided on the outer frame portion 34 and are formed in an annular shape in plan view. The first excitation electrode 32a and the second excitation electrode 32b are not electrically connected to the vibration-side first joining pattern 387a and the vibration-side second joining pattern 387b.

[0037] Furthermore, as shown in Figures 6 and 7, the piezoelectric diaphragm 3 has a connecting joint pattern 381 which is connected to a connecting joint pattern 386 formed on the second main surface 3b side of the outer frame 34 via internal wiring 39 formed on the inner wall surface of the outer frame 34. The internal wiring 39 is provided on the inner wall surface of the outer frame 34 that is aligned with the X-axis direction and on the +Z' side. In this case, the internal wiring 39 is formed in a V-shaped recess in plan view provided on the inner wall surface of the outer frame 34. The first excitation electrode 32a is connected to the piezoelectric vibrator connection terminal 23 via the connecting joint pattern 381, internal wiring 39, connecting joint pattern 386, the connecting joint pattern 25 of the lower plate 2 (described later), and via 272. The second excitation electrode 32b is connected to the piezoelectric vibrator connection terminal 21 via the connecting joint pattern 382, ​​the connecting joint pattern 26 (described later), and via 273.

[0038] The upper plate 4 is, for example, a rectangular parallelepiped substrate formed from a single quartz substrate 41. As shown in Figure 4, nothing is formed on the first main surface (upper surface) 4a of the upper plate 4 that does not face the piezoelectric diaphragm 3, and as shown in Figure 5, the second main surface (lower surface) 4b of the upper plate 4 that is joined to the piezoelectric diaphragm 3 is formed as a flat, smooth surface (mirror finish). It is preferable to use AT-cut quartz for the upper plate 4, similar to the piezoelectric diaphragm 3, in order to ensure that their thermal expansion coefficients are the same, but other quartz cut plates, piezoelectric substrates, glass substrates, etc. may also be used.

[0039] As shown in Figure 5, a sealing-side first bonding pattern 42 is formed on the second main surface 4b of the upper plate 4, serving as a sealing-side first sealing portion for bonding to the upper surface of the piezoelectric diaphragm 3. This sealing-side first bonding pattern 42 is formed in an annular shape in plan view, similar to the vibration-side first bonding pattern 387a of the piezoelectric diaphragm 3.

[0040] Furthermore, connection bonding patterns 43, 44, and 45 are formed on the second main surface 4b of the upper plate 4 at positions opposite to the connection bonding patterns 381, 383, and 385 of the piezoelectric diaphragm 3, respectively. The connection bonding patterns 43, 44, and 45 have substantially the same shape as the connection bonding patterns 381, 383, and 385 of the piezoelectric diaphragm 3, respectively.

[0041] As shown in Figures 9 and 10, the lower plate 2 is, for example, a rectangular parallelepiped substrate formed from a single quartz substrate 20, and the first main surface 2a of the lower plate 2 (the upper surface that is joined to the piezoelectric diaphragm 3) is formed as a flat, smooth surface (mirror finish). It is desirable to use AT-cut quartz for the lower plate 2 as well as the piezoelectric diaphragm 3 in order to ensure that the thermal expansion coefficients of both are the same, but other quartz cut plates, piezoelectric substrates, glass substrates, etc. may also be used.

[0042] As shown in Figure 9, a sealing-side second bonding pattern 24 is formed on the first main surface 2a of the lower plate 2, serving as a sealing-side second sealing portion for bonding to the piezoelectric diaphragm 3. The sealing-side second bonding pattern 24 is formed in an annular shape in plan view, similar to the vibration-side first and second bonding patterns 387a and 387b of the piezoelectric diaphragm 3 and the sealing-side first bonding pattern 42 of the upper plate 4.

[0043] Furthermore, a connecting bonding pattern 25 is formed in substantially the same shape as the connecting bonding pattern 386 of the piezoelectric diaphragm 3 on the first main surface 2a of the lower plate 2. A connecting bonding pattern 26 is formed on the first main surface 2a of the lower plate 2 at a position opposite the connecting bonding pattern 384 of the piezoelectric diaphragm 3, and this connecting bonding pattern 26 has a shape that extends from the A2 side towards the A1 direction along the long side on the B2 side.

[0044] And, as shown in FIG. 10, three connection terminals 21, 22, 23 are provided on the second main surface 2b which is the lower surface of the lower plate 2. Among them, two connection terminals 23, 21 are connection terminals for a piezoelectric vibrator that are respectively connected to the first and second excitation electrodes 32a, 32b of the piezoelectric vibration plate 3, and the remaining one connection terminal 22 is a ground connection terminal. Hereinafter, they will be referred to as the connection terminals 21, 23 for the piezoelectric vibrator and the ground connection terminal 22.

[0045] The ground connection terminal 22 and the connection terminals 23 for the piezoelectric vibrator are arranged in parallel along one long side on the B1 side of the rectangle of the lower plate 2, and the long connection terminal 21 for the piezoelectric vibrator in the A1 - A2 direction is arranged along the other long side on the B2 side of the rectangle of the lower plate 2. As shown in FIG. 10, the corner 21a in the A1 - B2 direction of the connection terminal 21 for the piezoelectric vibrator is cut out obliquely, so that it is difficult to interfere with the lower IC5 when the piezoelectric vibrator Pv is bent.

[0046] Also, as shown in FIGS. 9 and 10, conductors are filled inside through - holes penetrating the lower plate 2 to form vias 271, 272, 273. As shown in FIG. 9, the via 271 penetrates the second bonding pattern 24 on the sealing side slightly closer to the B1 direction on the A1 side and also penetrates the ground connection terminal 22. The via 272 penetrates the bonding pattern 25 for connection and the connection terminal 23 for the piezoelectric vibrator, and the via 273 penetrates the bonding pattern 26 for connection and the connection terminal 21 for the piezoelectric vibrator.

[0047] The connection terminals 23, 21 for the piezoelectric vibrator on the second main surface 2b which is the lower surface of the lower plate 2 are respectively superimposed on the piezoelectric vibrator mounting pads 63a, 63b provided on the stepped portion 62 of the base 6 and are joined by an adhesive as described later.

[0048] Thus, as described above, of the first and second excitation electrodes 32a and 32b of the piezoelectric diaphragm 3, the first excitation electrode 32a is connected to the connection terminal 23 for the piezoelectric vibrator on the second main surface 2b of the lower plate 2 via the connection bonding pattern 381, the internal wiring 39, the connection bonding pattern 386, the connection bonding pattern 25, and the via 272. Also, the second excitation electrode 32b is led out to the A1 side of the lower plate 2 via the connection bonding pattern 382 and the connection bonding pattern 26 and the via 273, and is connected to the end on the A1 side of the connection terminal 21 for the piezoelectric vibrator on the second main surface 2b of the lower plate 2.

[0049] Therefore, as shown in FIG. 9, the position where the first excitation electrode 32a of the piezoelectric diaphragm 3 is led out to the first main surface 2a of the lower plate 2 is the via 272, and similarly, the position where the second excitation electrode 32b is led out is the end on the A2 side of the connection bonding pattern 26. Further, the position where the second excitation electrode 32b is led out to the first main surface 2a extends through the connection bonding pattern 26 and to the via 273. And the positions where the first and second excitation electrodes 32a and 32b are led out to the second main surface 2b of the lower plate 2 are the vias 272 and 273 located at substantially opposite corners of the rectangle of the lower plate 2 and are electrically connected to the connection terminals 23 and 21 for the piezoelectric vibrator, respectively. Here, the connection terminals for the piezoelectric vibrator 23 and 21 correspond to the "two connection terminals" of the lower plate 2 in the present invention.

[0050] Then, the two adhesives 65 are disposed at positions overlapping the upper and lower sides of the inner wall of the outer frame portion 34 of the piezoelectric diaphragm 3 and the left side adjacent thereto, and the two piezoelectric vibrator mounting pads 63a and 63b of the base 6 and the two connection terminals 23 and 21 for the piezoelectric vibrator of the lower plate 2 of the piezoelectric vibrator Pv are respectively joined by the adhesive 65 made of silicone resin, the end on the A2 side of the piezoelectric vibrator Pv is fixed to the base 6, and the end on the A1 side of the piezoelectric vibrator Pv is a free end that is not fixed. <(

[0051] The inventors of this application conducted an investigation into the effects of tensile and compressive stresses between adhesives on a piezoelectric vibrator with a roughly rectangular shape in plan view, and obtained the following findings. Specifically, in a piezoelectric vibrator with a roughly rectangular shape in plan view, the susceptibility to stress varies depending on the direction of extension of the holding portion. When the two joining positions are aligned perpendicular to the direction of extension of the holding portion, the vibrator is susceptible to stress, while when the two joining positions are aligned parallel to the direction of extension of the holding portion, the vibrator is less susceptible to stress. Furthermore, the effect of stress can be mitigated if the two adhesives overlap the outer frame and part of the cutout of the piezoelectric vibrator in plan view.

[0052] In the piezoelectric vibration device 1 of this embodiment, as shown in Figure 2, adhesive 65 is placed at two locations spanning the outer frame portion 34, the cutout portion 36, and the vibrating portion 33 of the piezoelectric diaphragm 3 in a plan view, and is superimposed on the outer frame portion 34, the cutout portion 36, and a part of the vibrating portion 33. As a result, the piezoelectric vibrator Pv is less affected by stresses such as tensile stress and compressive stress between the two adhesive 65 locations, as well as stresses caused by thermal contraction of the adhesive 65. Here, by superimposing the adhesive 65 on the vibrating portion 33 as well, the bending stress related to the vibrating portion 33 can be reduced even if the free end bends. Note that the adhesive 65 only needs to be superimposed on at least the outer frame portion 34 and a part of the cutout portion 36, and does not need to be superimposed on the vibrating portion 33.

[0053] Therefore, according to the first embodiment, the two piezoelectric vibrator mounting pads 63a and 63b of the base 6 and the two piezoelectric vibrator connection terminals 23 and 21 of the lower plate 2 of the piezoelectric vibrator Pv are joined together with adhesive 65, and the two adhesives 65 are positioned so as to overlap the outer frame portion 34, the cutout portion 36, and the vibrating portion 33 of the piezoelectric diaphragm 3 in a plan view. As a result, the influence of stresses such as tensile stress and compressive stress between the adhesives 65, as well as stresses due to thermal contraction of the adhesives 65, on the vibrating portion of the piezoelectric diaphragm can be reduced.

[0054] Furthermore, since the cutout portion 36 of the piezoelectric diaphragm 3 is located closer to the center than the outer frame portion 34, the distance between the two adhesives 65 that join the two piezoelectric vibrator mounting pads 63a and 63b of the base 6 to the two piezoelectric vibrator connection terminals 23 and 21 of the piezoelectric vibrator Pv can be shortened, thereby suppressing displacement due to thermal contraction of the adhesives 65, such as tensile stress and compressive stress between the adhesives 65.

[0055] Furthermore, since the adhesive 65 is superimposed across the outer frame portion 34 of the piezoelectric vibrator 3, which has high mechanical strength, to which the lower plate 2 is joined, high bonding strength can be ensured for the entire piezoelectric vibrator Pv. In addition, the bonding strength can be improved while suppressing the transmission of restraining forces due to the thermal contraction effect of the adhesive 65, such as tensile stress and compressive stress between the adhesives 65, to the vibrating portion 33 of the piezoelectric vibrator Pv, thereby increasing the stability and reliability of the bonding of the piezoelectric vibrator Pv.

[0056] Furthermore, by joining the piezoelectric vibrator connection terminals 23 and 21 of the lower plate 2 to the piezoelectric vibrator mounting pads 63a and 63b with adhesive 65, the shrinkage force of the adhesive 65 during curing acts to lift the free end side of the lower plate 2, making it easier to maintain the lower plate 2 in a horizontal position. In addition, while using solder instead of adhesive 65 may cause the solder to wet and spread to unintended areas of the metal piezoelectric vibrator connection terminals, adhesive 65 does not wet and spread to metal, making it easy to control the bonding area.

[0057] Furthermore, in Figure 2, the adhesive 65 at two locations indicated by the dotted-dotted circled filled areas is positioned at two corners of the inner wall of the outer frame portion 34 of the piezoelectric diaphragm 3, overlapping with two adjacent sides of the rectangle of the inner wall, namely the upper and lower sides of the inner wall in Figure 2 and the adjacent left side. This improves the bonding strength between the piezoelectric vibrator Pv and the base 6.

[0058] Furthermore, the piezoelectric vibrator Pv has a three-layer laminated structure in which a piezoelectric diaphragm 3 having a vibrating section 33 including a pair of excitation electrodes 32a and 32b, and a lower plate 2 and an upper plate 4 are joined to the lower and upper surfaces of the piezoelectric diaphragm 3, respectively. Since the vibrating section 33 is further hermetically sealed inside the base 6, it becomes possible to provide a piezoelectric vibration device 1 with a double-sealed structure. Such double sealing makes it less susceptible to changes in the external environment and allows for the provision of a smaller piezoelectric vibration device 1 with more stable characteristics.

[0059] Furthermore, since silicone resin is used as the adhesive 65, the stress and strain are smaller compared to when epoxy resin is used, making it possible to minimize the stress and strain transmitted to the vibrating part 33 of the piezoelectric vibrator Pv due to the adhesive.

[0060] <Second Embodiment> The piezoelectric vibration device 1A according to the second embodiment of the present invention will be described with reference to Figures 11 and 12. Below, the differences between the piezoelectric vibration device 1A according to the second embodiment and the first embodiment will be described. In the following description, Figures 1 to 10 will also be referenced, and in Figures 11 and 12, the same reference numerals as in Figures 1 to 10 indicate the same or equivalent components.

[0061] The piezoelectric vibration device 1A according to the second embodiment differs from the piezoelectric vibration device 1 of the first embodiment in that, as shown by the dashed line in Figure 11 and the dashed line in Figure 12, the silicone resin adhesive 65A is formed in an elliptical shape that is longer in the A1-A2 direction (Z' axis direction) and shorter in the B1-B2 direction (X axis direction). In this case, as shown in Figure 11, the adhesive 65A is placed at two locations that span the outer frame portion 34, the cutout portion 36, and the vibrating portion 33 of the piezoelectric diaphragm 3 in a plan view, and overlaps with a part of the outer frame portion 34, the cutout portion 36, and the vibrating portion 33.

[0062] Therefore, according to the second embodiment, the same effects as the first embodiment described above can be obtained, and because the adhesive 65A is made into an ellipse shape that is long in the A1-A2 direction (Z' axis direction) and short in the B1-B2 direction (X axis direction), the bonding area of ​​the adhesive 65A can be increased, making the bonding strength greater than in the case of a circular shape. Moreover, by shortening the width of the adhesive 65A in the B1-B2 direction (X axis direction), the effect of reducing stress due to thermal contraction of the adhesive 65A on the vibrating part 33, such as tensile stress and compressive stress between the adhesives 65A, can be enhanced.

[0063] <Third Embodiment> The piezoelectric vibration device 1B according to the third embodiment of the present invention will be described with reference to Figure 13. The following describes the differences between the piezoelectric vibration device 1B according to the third embodiment and the first embodiment. In the following description, Figures 1 to 10 will also be referenced, and in Figure 13, the same reference numerals as in Figures 1 to 10 indicate the same or equivalent components.

[0064] The piezoelectric vibration device 1B according to the third embodiment differs from the first embodiment in that, instead of a three-layer stacked structure like the piezoelectric vibration device 1 of the first embodiment, it has a stacked structure in which the piezoelectric vibrator 30 is stacked on the lower plate 2, as shown in Figure 13.

[0065] Although not shown in Figure 13, the piezoelectric vibrator 30 comprises a piezoelectric substrate made of quartz, a substantially rectangular vibrating section in plan view on which a pair of excitation electrodes are formed on one main surface and the other main surface opposite to it, an outer frame section having an inner wall in plan view that is rectangular in shape and surrounds the outer wall of the vibrating section, a holding section that holds the vibrating section by connecting the outer wall of the vibrating section and the inner wall of the outer frame section, and a cutout section formed between the vibrating section and the outer frame section by cutting out the piezoelectric substrate in the thickness direction.

[0066] A piezoelectric vibrator 30 with this configuration is joined to the upper surface of the lower plate 2, for example, by Au-Au diffusion bonding, and the piezoelectric vibrator 30 is mounted on the upper surface of the lower plate 2. As shown in Figure 13, the piezoelectric vibrator connection terminals 23 and 21 (see Figure 10) on the lower surface of the lower plate 2 on which the piezoelectric vibrator 30 is mounted are joined to the piezoelectric vibrator mounting pads 63a and 63b of the base 6, respectively, using a silicone resin adhesive 65 similar to that of the first embodiment.

[0067] Therefore, according to the third embodiment, the same effects as those of the first embodiment described above can be obtained.

[0068] Furthermore, the present invention is not limited to the above-described configuration, and various design modifications can be made within the scope of the matters described in the claims.

[0069] For example, in the embodiments described above, the case was described in which circular and elliptical adhesives 65, 65A are placed at two locations that overlap the outer frame portion 34, the cutout portion 36, and the vibrating portion 33 of the piezoelectric diaphragm 3 in a plan view. However, it is sufficient that at least one of the two adhesives 65, 65A is placed at a location that overlaps the outer frame portion 34, the cutout portion 36, and the vibrating portion 33, and the other adhesive 65, 65A does not need to overlap the vibrating portion 33.

[0070] Furthermore, in each of the embodiments described above, the piezoelectric vibrator holding portion 35 is positioned at the +Z' and +X corners of the vibrating portion 33, for example as shown in Figure 6, and the adhesives 65 and 65A are placed close to the holding portion 35. However, as the piezoelectric vibration device 1C of the fourth embodiment, as shown in Figure 14, the piezoelectric vibrator holding portion 35C may be positioned at the A1 and B2 corners (-Z' and +X side in Figure 6) of the vibrating portion 33, and the circular and elliptical adhesives 65 and 65A may be placed at a distance from the holding portion 35C. Also, as the piezoelectric vibration device 1D of the fifth embodiment, as shown in Figure 15, the holding portion 35D may be positioned at the A1 and B1 corners (-Z' and -X side in Figure 6) of the vibrating portion 33, and the circular and elliptical adhesives 65 and 65A may be placed at a distance from the holding portion 35D. Thus, when the two joints formed by the adhesives 65 and 65A are located far from the holding parts 35C and 35D of the piezoelectric vibrator Pv, the effects of stress and strain from the adhesive are less likely to be transmitted to the vibrating part 33 of the piezoelectric vibrator Pv, thereby maintaining high stability and reliability in the joining of the piezoelectric vibrator Pv.

[0071] Furthermore, it is preferable that the two adhesives 65, 65A in each of the above embodiments be positioned within a distance of 1 / 4 of the length of the long side in the X-axis direction from each of the two short sides parallel to the Z' axis in the rectangle of the piezoelectric vibrator Pv, 30, thereby making it less likely for the piezoelectric vibrator Pv, 30 to tilt.

[0072] Furthermore, the two adhesives 65 and 65A in each of the above embodiments may be arranged parallel to the direction in which the holding portion 35D of the piezoelectric vibrator 3 in the piezoelectric vibrator Pv extends, as shown in the fifth embodiment in Figure 15. In this case, since the two adhesives 65 and 65A are arranged parallel to the direction in which the holding portion 35D of the piezoelectric vibrator Pv extends, the effects of stress and strain from the adhesives 65 and 65A are less likely to be transmitted to the vibrating portion 33 of the piezoelectric vibrator Pv, and high stability and reliability can be maintained in the bonding of the piezoelectric vibrator Pv.

[0073] Furthermore, as disclosed in each of the embodiments described above, the piezoelectric vibration device 1E is not limited to a configuration in which the vibrating part 33 is connected to the outer frame part 34 by a single holding part 35, 35C, 35D, but may also be a configuration in which the vibrating part 33 is connected to the outer frame part 34 by a plurality of holding parts, as shown in the sixth embodiment in Figure 16. In other words, even if the vibration section 33 is connected to the outer frame section 34 by a composite holding section 35E having a pair of first cutouts 361 having an elongated rectangular shape in the direction perpendicular to a virtual straight line L1 passing through the center point of the vibration section 33 in a plan view, and a second cutout 362 having a U shape between the pair of first cutouts 361, with the virtual straight line L1 in between, and a pair of vibration holding sections 351 formed along the virtual straight line L1 between the opposing ends of the pair of second cutouts 362, and a pair of outer frame holding sections 352 formed extending in a direction perpendicular to the virtual straight line L1 and connecting each vibration holding section 351 to two locations on the inner circumferential wall of the outer frame section 34, the same effects as the first embodiment described above can be obtained.

[0074] Furthermore, as disclosed in each of the embodiments described above, the piezoelectric vibration device is not limited to a configuration in which the free end of the piezoelectric vibrator Pv, 30 is arranged so as to overlap the IC 5 in a plan view within the base 6. It may also be a piezoelectric vibration device in which the free end of the piezoelectric vibrator Pv, 30 does not overlap the IC 5 in a plan view above, and the entire piezoelectric vibrator Pv, 30 is arranged on the stepped portion 62.

[0075] Furthermore, the base 6 shown in Figure 1 may have a configuration that only has a recess without a stepped portion 62, and the piezoelectric vibrator and IC may be arranged in the recess without overlapping in a plan view to form a piezoelectric vibration device.

[0076] Furthermore, as a seventh embodiment of the present invention, as shown in Figure 17, the piezoelectric vibration device 1F may have a configuration without an IC 5, in which piezoelectric vibrator P is placed on the upper surface of the base 6F by bonding piezoelectric vibrator mounting pads 63a and 63b provided on the upper surface of a flat base 6F to piezoelectric vibrator connecting terminals 23 and 21 of the lower plate 2 with adhesive 65, similar to the piezoelectric vibrator Pv shown in Figure 1, and the upper surface of the base 6F is closed and airtightly sealed with a cup-shaped lid 71 having a U-shaped cross-section. Note that the piezoelectric vibrator mounting pad 63a and the piezoelectric vibrator connecting terminal 23 bonded thereto are not shown in Figure 13, and Figure 17 shows a cross-section of the piezoelectric vibrator mounting pad 63b with the piezoelectric vibrator connecting terminal 21 bonded thereto.

[0077] Furthermore, as an eighth embodiment of the present invention, as shown in Figure 18, the base 6 does not have the stepped portion 62 in Figure 1 but only has a recess 61, and a piezoelectric vibrator Pv (or the piezoelectric vibrator 30 in Figure 13) is placed in the recess 61 and the recess 61 is airtightly sealed with a cover 7, a wall member 67 is provided on the peripheral edge of the lower surface of the base 6 to form a recess 68 in the center, and an electronic component such as an IC 5G is placed in the recess 68 on the lower surface to form a piezoelectric vibration device 1G.

[0078] Furthermore, one or both of the A1-side edges of the two adhesives 65 shown in Figure 2 may reach the A1-side edge of the stepped portion 62 shown in Figure 3. Alternatively, one or both of the two adhesives 65 shown in Figure 2 may overlap the outer frame portion 34 in a position that is biased towards the A2 side than the position shown in Figure 2, and one or both of the A1-side edges of the adhesives 65 may be positioned to overlap a part of the A2 side of the cutout portion 36.

[0079] Furthermore, the connection terminals provided on the lower surface of the lower plate 2 of the piezoelectric vibrator P,30 are not limited to a three-terminal configuration consisting of three connection terminals 21 to 23 as shown in Figure 12, but may also be a two-terminal or four-terminal configuration.

[0080] Furthermore, the upper plate 4 of the piezoelectric vibrator Pv, the piezoelectric diaphragm 3, and the lower plate 2 may be made up of different crystal cut plates, or the same crystal cut plates may be used. If the same crystal cut plates are used, they may be stacked aligned along the same crystal axis. In this case, stacking them with the crystal axes aligned is even more desirable because it results in the same coefficient of thermal expansion.

[0081] Furthermore, although the vibrating part of the piezoelectric vibrator is described as rectangular (AT cut) in the above-described embodiment, it is not limited to this, and may be rectangular (SC cut, etc.) or even tuning fork shaped.

[0082] Furthermore, in the above-described embodiment, the piezoelectric vibrator mounting pads 63a and 63b were described as being electrically connected to the piezoelectric vibrator connection terminals 23 and 21 of the lower plate 2, respectively, by an adhesive 65 made of silicone resin, for example. However, the adhesive may be a conductive adhesive made of epoxy resin, or an insulating adhesive and wire may be combined.

[0083] Alternatively, instead of the vias 271, 272, and 273 described above, through-holes with conductors attached to their interiors may be formed.

[0084] Furthermore, in piezoelectric vibration devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G, the material used for the piezoelectric resonator Pv, 30 is not limited to quartz as long as it performs piezoelectric vibration.

[0085] Furthermore, the electronic components housed within the base 6 are not limited to the ICs 5 and 5G described above, but may also be temperature sensors. Note that electronic components are not required.

[0086] Furthermore, the above-described embodiment is applicable to both temperature sensor-integrated oscillators, SPXOs (Simple Packaged Crystal Oscillators), and TCXOs (Temperature Compensated Crystal Oscillators).

[0087] The present invention is widely applicable to piezoelectric vibration devices comprising a base and a piezoelectric vibrator mounted on the base.

[0088] 1, 1A, 1B, 1C, 1D, 1E ... Piezoelectric vibration device 2 ... Bottom plate 21, 23 ... Connection terminals for piezoelectric vibrators 3 ... Piezoelectric diaphragm 32a, 32b ... First and second excitation electrodes 33 ... Vibration part 34 ... Outer frame part 35, 35C, 35D ... Holding part 351 ... Vibration holding part 352 ... Outer frame holding part 35E ... Composite holding part 36 ... Cutout part 361 ... First cutout part 362 ... Second cutout part 4 ... Top plate Pv, 30 ... Piezoelectric vibrator 6, 6F ... Base 6a ... Outer bottom surface 62 ... Step part (mounting part) 63a, 63b ... Piezoelectric vibrator mounting pad (pad part) 65, 65A ... Adhesive OUT ... External connection terminal

Claims

1. A piezoelectric vibration device comprising a base and a piezoelectric vibrator mounted on the base, wherein the base is made of an insulating substrate which is substantially rectangular in plan view, the outer bottom surface of the insulating substrate has an external connection terminal, the surface of the insulating substrate opposite to the outer bottom surface has a mounting portion for mounting the piezoelectric vibrator and two pad portions provided in the mounting portion for joining the piezoelectric vibrator to the insulating substrate, the piezoelectric vibrator mounted in the mounting portion is hermetically sealed by a cover, the piezoelectric vibrator has a laminated structure of a piezoelectric diaphragm and a lower plate on which the piezoelectric diaphragm is mounted, the piezoelectric diaphragm has an outer frame portion which is substantially rectangular in plan view to which the lower plate is joined, a vibrating portion which is substantially rectangular in plan view on which a pair of excitation electrodes are formed, a cutout portion between the outer frame portion and the vibrating portion, and a holding portion which connects the vibrating portion and the outer frame portion, the lower plate is made of a substrate which is substantially rectangular in plan view and has at least two connection terminals on its bottom surface that are connected to the pair of excitation electrodes, the piezoelectric vibrator is, A piezoelectric vibration device characterized in that, at one end, two joining points between the two pad portions of the base and the two connection terminals of the piezoelectric vibrator are joined by adhesive, the other end opposite to the two joining points forms a free end and is mounted on the mounting portion, and at least one of the adhesives that join the two pad portions and the two connection terminals is positioned to overlap the outer frame portion and a part of the cutout portion of the piezoelectric diaphragm.

2. The piezoelectric vibrator according to claim 1, further comprising an upper plate superimposed on the side of the piezoelectric vibrating plate opposite to the mounting surface on the lower plate, and which, together with the lower plate, hermetically seals the vibrating portion of the piezoelectric vibrating plate.

3. The piezoelectric vibration device according to claim 1 or 2, wherein the outer frame portion has an inner wall that is substantially rectangular in plan view, and the adhesive that joins the two pad portions of the base and the two connection terminals of the piezoelectric vibrator is positioned at the corner of the inner wall of the outer frame portion and overlaps with two adjacent sides of the rectangle of the inner wall.

4. The piezoelectric vibration device according to claim 1 or 2, characterized in that the two joints made by the adhesive are located away from the holding portion.

5. The piezoelectric vibration device according to claim 4, characterized in that the adhesives used to join the two pad portions of the base and the two connection terminals of the piezoelectric vibrator are arranged parallel to the direction in which the holding portion extends.

6. The piezoelectric vibration device according to claim 1 or 2, characterized in that the adhesive is made of silicone resin.

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