Piezoelectric vibration device

Abstract

To prevent cracking of a sealing plate when bonding electronic component elements to the sealing plate of a piezoelectric vibration device using metal bumps, thereby providing the piezoelectric vibration device with excellent reliability.SOLUTION: Seven electrode parts for connecting a sealing plate are arranged on the bottom surface of an IC chip (electronic component element), seven electrode parts 37a to 37g for connecting the electronic component elements, each of which connects to the electrode parts for connecting the sealing plate of IC chips, are arranged on an upper electrode pattern 37 of a first sealing member (upper sealing plate) 3, which does not face a piezoelectric vibration plate 2, and metal bumps are used to bond the seven electrode parts for connecting the sealing plate of the IC chip to the seven electrode parts 37a to 37g for connecting the electronic component elements on the upper sealing plate 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, there is a laminated piezoelectric vibration device in which a sealing plate is laminated and integrated onto a vibration plate, and electronic component elements such as IC chips are connected using metal bumps (see, for example, Patent Document 1). In detail, one main surface of a piezoelectric substrate having a vibration portion and an outer frame portion surrounding the periphery of the vibration portion is covered with a first sealing member to seal the vibration portion, and the other main surface of the piezoelectric substrate is covered with a second sealing member to seal the vibration portion, external electrodes to which electronic component elements are connected are provided on at least one of the first sealing member and the second sealing member, and the electronic component elements are connected to the external electrodes of the sealing member using metal bumps at six positions that overlap part or all of the outer frame portion of the piezoelectric substrate in a plan view, thereby forming a piezoelectric vibration device.

[0003] In recent years, this type of piezoelectric vibration device has become increasingly smaller, with devices being developed that are smaller than the electronic components such as IC chips that are connected to it. Furthermore, the variety of oscillation ICs that meet the required oscillation characteristics is also increasing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6737326 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as piezoelectric resonator devices become smaller, electronic components such as ICs mounted on piezoelectric resonator devices also become smaller and more diverse. As piezoelectric resonator devices become smaller, the conventional method of electrically connecting electronic components to a sealing member of a piezoelectric resonator device using metal bumps can lead to cracks in the sealing member if the pressure applied during bonding is too strong, while a weak pressure can lead to insufficient bonding strength. Therefore, to ensure sufficient bonding strength, stress from the pressure applied during bonding can concentrate in a specific area of ​​the sealing member, causing bending and cracking, potentially reducing the reliability of the piezoelectric resonator device. Therefore, it becomes necessary to bond the metal bumps in a location that does not adversely affect the sealing member.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a piezoelectric vibration device that is highly reliable by preventing cracking of the sealing plate when an external electronic component element is joined to the sealing plate of the piezoelectric vibration device using metal bumps. [Means for solving the problem]

[0007] In order to achieve the above object, a piezoelectric vibration device according to the present invention provides a piezoelectric vibration device in which a piezoelectric vibration plate is hermetically sealed by upper and lower sealing plates that cover the upper and lower surfaces of the piezoelectric vibration plate, and an electronic component element is electrically and mechanically bonded to the upper surface side of the upper sealing plate using metal bumps, wherein the piezoelectric vibration plate has a substantially rectangular shape and comprises: a vibration portion that is rectangular in plan view and on which a pair of excitation electrodes are formed; an outer frame portion that has an inner peripheral wall that is rectangular in plan view and surrounds the outer peripheral wall of the vibration portion; a holding portion that connects the outer peripheral wall of the vibration portion and the inner peripheral wall of the outer frame portion; and a cutout portion that is formed by cutting out the piezoelectric vibration plate in the plate thickness direction between the vibration portion and the outer frame portion, and the outer frame portion is formed thicker than the vibration portion and the holding portion, and the upper sealing plate is the upper sealing plate has a rectangular shape substantially identical to that of the piezoelectric diaphragm, covers the upper surface of the piezoelectric diaphragm to seal the vibrating portion, the lower sealing plate has a rectangular shape substantially identical to that of the piezoelectric diaphragm, covers the lower surface of the piezoelectric diaphragm to seal the vibrating portion, the electronic component element has an area in a plan view smaller than that of the upper sealing plate and the lower sealing plate, and has seven or more sealing plate connecting electrode portions formed on its lower surface, and the upper sealing plate has an upper surface that does not face the piezoelectric diaphragm, and has seven or more electronic component element connecting electrode portions to which the seven or more sealing plate connecting electrode portions are respectively connected, and the metal bumps electrically connect the seven or more sealing plate connecting electrode portions of the electronic component element to the seven or more electronic component element connecting electrode portions of the upper sealing plate, respectively.

[0008] According to this configuration, when six or fewer sealing plate connecting electrode portions are joined to electronic component element connecting electrode portions, it is not possible to disperse stress because joining is not possible at two points in the center of the long rectangular side of the electronic component element. In contrast, since this configuration joins seven or more sealing plate connecting electrode portions to electronic component element connecting electrode portions, when the electronic component element is joined to the upper sealing plate with metal bumps, it is possible to disperse stress caused by pressing during joining, preventing the stress from concentrating on one part of the upper sealing plate and preventing cracking of the upper sealing plate.

[0009] The seven or more sealing plate connecting electrodes of the electronic component element may be formed on the periphery.

[0010] According to this configuration, by forming seven or more sealing plate connection electrode portions of the electronic component element on the peripheral portion, the stress caused by the pressure when joining the electronic component element to the upper sealing plate using metal bumps can be effectively dispersed.

[0011] The seven or more sealing plate connecting electrodes of the electronic component element may be formed at least at three corners of the electronic component element and at two or more locations in the center of a pair of long sides.

[0012] According to this configuration, when the electronic component element is bonded to the upper sealing plate with a metal bump, the stress due to pressure is greatest at the center of the long sides of the electronic component element. However, the sealing plate connection electrode portions can be formed at two or more locations on either side of the lines connecting at least three corners of the rectangle of the electronic component element and the centers of a pair of long sides, thereby dispersing the stress at the center of the long sides of the electronic component element.

[0013] In this case, by forming sealing plate connection electrodes at three corners of the rectangle of the electronic component element, at least one diagonal portion corresponding to the maximum width dimension when the electronic component element is joined and two points on the long and short sides can be joined together, which makes it possible to suppress displacement of the upper sealing plate located above the vibration part of the piezoelectric diaphragm and prevent cracking of the upper sealing plate and poor bonding strength. Also, by forming sealing plate connection electrodes at two or more points in the center of the long sides of the rectangle of the electronic component element, it is possible to suppress the amount of deflection of the long sides of the rectangle of the electronic component element and suppress displacement of the upper sealing plate located above the vibration part of the piezoelectric diaphragm, thereby preventing cracking of the upper sealing plate.

[0014] In addition, the seven or more electrode portions for connecting electronic component elements of the upper sealing plate may be formed in a rectangular area in a plan view inside the inner wall of the outer frame portion of the piezoelectric vibration plate, and one or more electrode portions for connecting electronic component elements along one long side of the rectangular area may be formed in the shape of a floating island that is not connected to anything.

[0015] This configuration allows the piezoelectric diaphragm to be arranged in a rectangular region inward from the inner peripheral wall of the outer frame of the piezoelectric diaphragm in a plan view, making it possible to mount smaller electronic components. Furthermore, when bonding the electronic components to the upper sealing plate using metal bumps, deflection in the rectangular region inward from the inner peripheral wall of the outer frame of the piezoelectric diaphragm can be suppressed, preventing stress concentration due to pressure during bonding when mounting smaller electronic components. Furthermore, by forming one or more electronic component connection electrodes as floating islands that are not connected to anything, it is possible to avoid overcrowding of the electronic component connection electrodes, effectively suppressing deflection due to stress in the rectangular region inward from the inner peripheral wall of the outer frame of the piezoelectric diaphragm, and preventing cracking of the upper sealing plate.

[0016] In addition, it is preferable that the width of the portion of the outer frame portion of the piezoelectric diaphragm that corresponds to the short sides of the rectangle is greater than the width of the portion that corresponds to the long sides.

[0017] With this configuration, the electrode portion for connecting the sealing plate and the electrode portion for connecting the electronic component element can be joined at a position close to the short side portion of the outer frame of the piezoelectric diaphragm, which is wider and stronger than the long side, thereby reliably preventing cracking of the upper sealing plate due to the stress of pressure during joining. [Effects of the Invention]

[0018] According to the present invention, when an electronic component element is bonded to a sealing plate of a piezoelectric vibration device using a metal bump, the stress caused by the pressure during bonding can be dispersed, preventing cracking of the sealing plate, thereby making it possible to provide a highly reliable piezoelectric vibration device. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a piezoelectric vibration device according to an embodiment of the present invention. [Figure 2] 2 is a schematic plan view of a first main surface side of a first sealing member (upper sealing plate) of the piezoelectric vibration device of FIG. 1. FIG. [Figure 3]2 is a schematic bottom view of the second main surface side of the first sealing member of the piezoelectric vibration device of FIG. 1. FIG. [Figure 4] 2 is a schematic plan view of a first main surface side of a piezoelectric vibration plate of the piezoelectric vibration device of FIG. 1. FIG. [Figure 5] 2 is a schematic bottom view of the second main surface side of the piezoelectric vibration plate of the piezoelectric vibration device of FIG. 1. FIG. [Figure 6] 2 is a schematic plan view of a first main surface side of a second sealing member (lower sealing plate) of the piezoelectric vibration device of FIG. 1. FIG. [Figure 7] 2 is a schematic bottom view of the second main surface side of the second sealing member of the piezoelectric vibration device of FIG. 1. FIG. [Figure 8] 2 is a schematic bottom view of an electronic component element (IC chip) connected to the piezoelectric vibration device of FIG. 1. FIG. [Figure 9] 10 is a schematic plan view of a first main surface side of a first sealing member of a piezoelectric vibration device according to a second embodiment of the present invention. FIG. [Figure 10] 10 is a schematic plan view of a first main surface side of a first sealing member of a piezoelectric vibration device according to a third embodiment of the present invention. FIG. [Figure 11] 11 is a schematic bottom view of an electronic component element (IC chip) connected to the piezoelectric vibration device of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] First Embodiment A piezoelectric vibration device according to a first embodiment of the present invention will be described in detail with reference to Figures 1 to 8. In the following first embodiment, a case will be described in which quartz crystal is used for the piezoelectric vibration plate. However, in the piezoelectric vibration device of the present invention, the material used for the piezoelectric vibration plate is not limited to quartz crystal as long as it generates piezoelectric vibrations.

[0021] As shown in FIG. 1, the piezoelectric vibration device 101 according to the first embodiment includes a piezoelectric diaphragm 2, a first sealing member 3, a second sealing member 4, and an IC chip 5. In this piezoelectric vibration device 101, the piezoelectric diaphragm 2 is bonded to the first sealing member 3, and the piezoelectric diaphragm 2 is bonded to the second sealing member 4 to form a package 12 that serves as a piezoelectric vibrator with a substantially rectangular parallelepiped sandwich structure. An IC chip 5 is mounted on the main surface of the first sealing member 3 opposite to the surface bonded to the piezoelectric diaphragm 2. The IC chip 5, which serves as an electronic component, is a one-chip integrated circuit element that, together with the piezoelectric diaphragm 2, forms an oscillator circuit. Here, the first sealing member 3 and the second sealing member 4 correspond to the "upper sealing plate" and "lower sealing plate" of the present invention.

[0022] In the piezoelectric diaphragm 2, a first excitation electrode 221 is formed on one of the main surfaces, that is, a first main surface 211, and a second excitation electrode 222 is formed on the other main surface, that is, a second main surface 212. In the piezoelectric vibrating device 101, a first sealing member 3 and a second sealing member 4 are bonded to both main surfaces (the first main surface 211, the second main surface 212) of the piezoelectric diaphragm 2, respectively, to form an internal space of the package 12, and a vibrating part 22 (see FIGS. 4 and 5) including the first excitation electrode 221 and the second excitation electrode 222 is hermetically sealed in the internal space.

[0023] The piezoelectric vibration device 101 according to the first embodiment has a package size of, for example, 1.0 × 0.8 mm, and is designed to be compact and low-profile. In addition, in order to achieve the miniaturization, the package 12 does not have castellations, but rather uses through-holes (described later) to achieve electrode conduction.

[0024] Next, the piezoelectric vibration plate 2, the first sealing member 3, and the second sealing member 4 of the piezoelectric vibration device 101 will be described with reference to Figures 1 to 7. Note that the following describes each of the components that are configured as individual components that are not joined together.

[0025] As shown in Figures 4 and 5, the piezoelectric diaphragm 2 is a piezoelectric substrate made of quartz crystal, and both of its main surfaces (first main surface 211, second main surface 212) are formed as flat, smooth surfaces (mirror-finished). In the first embodiment, an AT-cut quartz crystal plate that performs thickness-shear vibration is used as the piezoelectric diaphragm 2. In the piezoelectric diaphragm 2 shown in Figures 4 and 5, both main surfaces 211, 212 of the piezoelectric diaphragm 2 are in the XZ' plane.

[0026] In this XZ' plane, the direction parallel to the short side (short side) of the piezoelectric diaphragm 2 is the X-axis direction, and the direction parallel to the long side (long side) of the piezoelectric diaphragm 2 is the Z'-axis direction. Note that AT-cut is a processing technique in which artificial quartz is cut at an angle of 35°15' around the X-axis relative to the Z-axis, one of the three crystal axes of the 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 the axes tilted 35°15' from the Y-axis and Z-axis, respectively, of the crystal axes of the quartz. The Y'-axis and Z'-axis directions correspond to the cutting direction when cutting the AT-cut quartz plate. Note that the piezoelectric diaphragm 2 is not limited to the AT-cut quartz plate described above; an SC-cut quartz plate or a tuning fork-type vibrator may also be used.

[0027] The piezoelectric diaphragm 2 has a vibration section 22 having a substantially rectangular shape in plan view, on both main surfaces 211, 212 of which a pair of excitation electrodes (a first excitation electrode 221 and a second excitation electrode 222 each having a substantially rectangular shape) are formed, an outer frame section 23 having a rectangular shape in plan view and surrounding the outer peripheral wall of the vibration section 22, a holding section 24 that holds the vibration section 22 by connecting the outer peripheral wall of the vibration section 22 and the inner peripheral wall of the outer frame section 23, and a cutout section 25 formed by cutting out the piezoelectric diaphragm 2 in the plate thickness direction between the vibration section 22 and the outer frame section 23. In other words, the piezoelectric diaphragm 2 has a configuration in which the vibration section 22, the outer frame section 23, and the holding section 24 are integrally provided. Here, the outer frame section 23 is formed so that the width of the portion corresponding to the short sides of the rectangle of the piezoelectric diaphragm 2 is larger than the portion corresponding to the long sides.

[0028] In the first embodiment, the holding portion 24 is provided at only one location between the vibrating portion 22 and the outer frame portion 23. Furthermore, the vibrating portion 22 and the holding portion 24 are formed thinner than the outer frame portion 23. Due to this difference in thickness between the outer frame portion 23 and the holding portion 24, the natural frequencies of the piezoelectric vibrations of the outer frame portion 23 and the holding portion 24 differ, and propagation of the vibration excited in the vibrating portion 22 is suppressed. Furthermore, a space is formed by bonding the first sealing member 3 and the second sealing member 4 to the piezoelectric diaphragm 2, and the space is sealed. Note that the location where the holding portion 24 is formed is not limited to one location, and it may be provided at two or more locations between the vibrating portion 22 and the outer frame portion 23.

[0029] The holding portion 24 extends (protrudes) in the -Z' direction from only one corner of the vibrating portion 22, which is located in the +X direction and the -Z' direction. In this way, the holding portion 24 is provided at a corner of the outer periphery of the vibrating portion 22, where the displacement of the piezoelectric vibration is relatively small. Therefore, compared to when the holding portion 24 is provided at a portion other than the corner (the center of the side), it is possible to prevent the piezoelectric vibration from leaking to the outer frame portion 23 via the holding portion 24, and it is possible to more efficiently piezoelectrically vibrate the vibrating portion 22. Furthermore, compared to when the holding portion 24 is provided at two or more locations, it is possible to reduce the stress acting on the vibrating portion 22, thereby reducing the frequency shift of the piezoelectric vibration caused by such stress and improving the stability of the piezoelectric vibration.

[0030] The first excitation electrode 221 is provided on the first main surface 211 side of the vibrating section 22, and the second excitation electrode 222 is provided on the second main surface 212 side of the vibrating section 22. Lead wiring (first lead wiring 223, second lead wiring 224) for connecting these excitation electrodes to external electrode terminals is connected to the first excitation electrode 221 and the second excitation electrode 222. The first lead wiring 223 is led out from the first excitation electrode 221 and connected to a connection bonding pattern 27 formed on the outer frame section 23 via the holding section 24. The second lead wiring 224 is led out from the second excitation electrode 222 and connected to a connection bonding pattern 28 formed on the outer frame section 23 via the holding section 24. In this way, the first lead wiring 223 is formed on the first main surface 211 side of the holding section 24, and the second lead wiring 224 is formed on the second main surface 212 side of the holding section 24.

[0031] Both main surfaces (first main surface 211 and second main surface 212) of the piezoelectric diaphragm 2 are provided with vibration-side sealing portions for bonding the piezoelectric diaphragm 2 to the first sealing member 3 and the second sealing member 4, respectively. The vibration-side sealing portion on the first main surface 211 is provided with a vibration-side first bonding pattern 251 for bonding to the first sealing member 3. The vibration-side sealing portion on the second main surface 212 is provided with a vibration-side second bonding pattern 252 for bonding to the second sealing member 4. The vibration-side first bonding pattern 251 and the vibration-side second bonding pattern 252 are provided on the outer frame portion 23 and are formed in an annular shape in a plan view. The first excitation electrode 221 and the second excitation electrode 222 are not electrically connected to the vibration-side first bonding pattern 251 and the vibration-side second bonding pattern 252.

[0032] 4 and 5, the piezoelectric diaphragm 2 has five through holes formed therein that penetrate between the first main surface 211 and the second main surface 212. Specifically, the four first through holes 261 are provided in the four corner regions of the outer frame portion 23, respectively. The second through hole 262 is provided in the outer frame portion 23, on one side in the Z′-axis direction of the vibration portion 22 (the −Z′ direction side in FIGS. 4 and 5). A connection bonding pattern 253 is formed around each of the first through holes 261. Furthermore, a connection bonding pattern 254 is formed on the first main surface 211 side around the second through hole 262, and a connection bonding pattern 28 is formed on the second main surface 212 side around the second through hole 262.

[0033] In the first through hole 261 and the second through hole 262, a through electrode for achieving electrical continuity between the electrodes formed on the first main surface 211 and the second main surface 212 is formed along the inner wall surface of each through hole. In addition, the central portion of each of the first through hole 261 and the second through hole 262 is a hollow through portion that penetrates between the first main surface 211 and the second main surface 212.

[0034] In the piezoelectric diaphragm 2, the first excitation electrode 221, the second excitation electrode 222, the first escape wiring 223, the second escape wiring 224, the first bonding pattern 251, the vibration-side second bonding pattern 252, and the connection bonding patterns 253, 254, 27, and 28 can be formed in the same process. Specifically, these can be formed from base films formed by physical vapor deposition on both main surfaces 211 and 212 of the piezoelectric diaphragm 2, and bonding films formed by physical vapor deposition on the base films. In the first embodiment, Ti (or Cr) is used for the base films, and Au is used for the bonding films.

[0035] 2 and 3, the first sealing member 3 is, for example, a rectangular parallelepiped substrate formed from a single piezoelectric substrate made of quartz, and the second main surface 312 (the lower surface that bonds to the piezoelectric diaphragm 2) of this first sealing member 3 is formed as a flat, smooth surface (mirror-finished). Note that it is preferable to use an AT-cut quartz similar to that used for the piezoelectric diaphragm 2 for the first sealing member 3 so that the thermal expansion coefficients of the two can be made the same, but other quartz cut plates, piezoelectric substrates, glass substrates, etc. may also be used.

[0036] 2, seven electrode patterns 37 are formed on the first main surface 311 (top surface on which the IC chip 5 is mounted) of the first sealing member 3 that does not face the piezoelectric diaphragm 2, and these electrode patterns 37 are formed so that some or all of them are located on the periphery of a rectangular area R (the rectangular area indicated by the dashed dotted line in FIG. 2) that includes the mounting pads of the IC chip 5, and are used as electronic component element connecting electrodes 37a, 37b, 37c, 37d, 37e, 37f, and 37g to which seven sealing plate connecting electrodes of the IC chip 5, which will be described later, are connected. Note that this rectangular area R is located inside the inner peripheral wall of the outer frame portion 23 of the piezoelectric diaphragm 2.

[0037] The electronic component element connecting electrodes 37a-37g include mounting pads for the IC chip 5, as shown by the dashed-dotted line in FIG. 2, and are arranged on the periphery of a rectangular region R in a plan view, inside the inner peripheral wall of the outer frame portion 23 of the piezoelectric diaphragm 2. Specifically, the electronic component element connecting electrodes 37a, 37d, and 37g are arranged at three corners of the rectangular region R, the electronic component element connecting electrodes 37b and 37c are arranged along the long side on the A2 side of the rectangular region R, offset in the B1 and B2 directions from the center of the long side, and the electronic component element connecting electrodes 37f and 37e are arranged along the long side on the A1 side of the rectangular region R, offset sequentially in the B2 direction from the center of the long side, with the electronic component element connecting electrode 37e being slightly offset in the A2 direction from the corner. Note that the electronic component element connecting electrode 37e does not have to be offset in this manner. The electronic component element connecting electrode portion 37d does not have an electrical connection function, but serves only as an electrode portion having a mechanical joining function with a metal bump, which will be described later.

[0038] Among the electronic component element connecting electrodes 37a to 37g, the electronic component element connecting electrode portions 37a and 37g, the electronic component element connecting electrode portions 37c and 37f, and the electronic component element connecting electrode portions 37d and 37e are arranged so as to line up on the same line in the short side direction (A1-A2 direction) of the rectangular region R. Here, the electronic component element connecting electrode portions 37a to 37g are arranged near third, fourth, and fifth through holes 322, 323, and 324 of the first sealing member 3, which will be described later.

[0039] These electronic component element connecting electrodes 37a to 37g are bonded to the sealing plate connecting electrodes of the IC chip 5 by FCB (Flip Chip Bonding) using metal bumps (for example, Au bumps) 38 (see FIG. 1).

[0040] As shown in FIGS. 2 and 3 , the first sealing member 3 has six through holes formed therein, each connected to the electrode patterns 37 located at the four corners and two electrode patterns 37 at the centers of opposing short sides, and penetrating between the first main surface 311 and the second main surface 312. Specifically, four third through holes 322 are provided in the areas of the electrode patterns 37 at the four corners (corner portions) of the first sealing member 3. Fourth and fifth through holes 323 and 324 are provided in the electrode patterns 37 at the centers of opposing short sides in the A2 and A1 directions in FIGS. 2 and 3, respectively. The A1 and A2 directions in FIGS. 2, 3, 6, and 7 correspond to the −Z′ and +Z′ directions in FIGS. 4 and 5, respectively, and the B1 and B2 directions in FIGS. 2, 3, 6, and 7 correspond to the −X and +X directions in FIGS. 4 and 5, respectively.

[0041] In the third through hole 322 and the fourth and fifth through holes 323, 324, through electrodes for achieving electrical continuity between the electrodes formed on the first main surface 311 and the second main surface 312 are formed along the inner wall surfaces of the respective through holes. In addition, the central portions of the third through hole 322 and the fourth and fifth through holes 323, 324 form hollow through portions that penetrate between the first main surface 311 and the second main surface 312.

[0042] A sealing-side first bonding pattern 321 is formed on the second main surface 312 of the first sealing member 3 as a sealing-side first sealing portion for bonding to the piezoelectric diaphragm 2. The sealing-side first bonding pattern 321 is formed in a ring shape in a plan view.

[0043] Furthermore, on the second main surface 312 of the first sealing member 3, a connection joint pattern 34 is formed at each of the four corners (corner portions) of the third through hole 322. A connection joint pattern 351 is formed around the fourth through hole 323, and a connection joint pattern 352 is formed around the fifth through hole 324. Furthermore, a connection joint pattern 353 is formed on the opposite side of the long axis direction of the first sealing member 3 from the connection joint pattern 351 (A1 direction side), and the connection joint pattern 351 and the connection joint pattern 353 are connected by a wiring pattern 33. Note that the connection joint pattern 353 is not connected to the connection joint pattern 352.

[0044] In the first sealing member 3, the electrode pattern 37, the sealing-side first bonding pattern 321, the connection bonding patterns 34, 351 to 353, and the wiring pattern 33 can be formed in the same process. Specifically, these can be formed from an underlayer formed by physical vapor deposition on the first and second main surfaces 311, 312 of the first sealing member 3, and a bonding film formed by physical vapor deposition on the underlayer. In this embodiment, Ti (or Cr) is used for the underlayer, and Au is used for the bonding film.

[0045] 6 and 7, the second sealing member 4 is, for example, a rectangular parallelepiped substrate formed from a single piezoelectric substrate made of quartz, and the first main surface 411 (the upper surface that bonds to the piezoelectric diaphragm 2) of this second sealing member 4 is formed as a flat, smooth surface (mirror-finished). Note that it is preferable to use an AT-cut quartz similar to that used for the piezoelectric diaphragm 2 for the first sealing member 3 so that the thermal expansion coefficients of the two can be made the same, but other quartz cut plates, piezoelectric substrates, glass substrates, etc. may also be used.

[0046] A sealing-side second bonding pattern 421 is formed on the first main surface 411 of the second sealing member 4 as a sealing-side second sealing portion for bonding to the piezoelectric diaphragm 2. The sealing-side second bonding pattern 421 is formed in a ring shape in a plan view.

[0047] Four external electrode terminals 43 for electrical connection to the outside are provided on the second main surface 412 (the outer lower surface not facing the piezoelectric diaphragm 2) of the second sealing member 4. The external electrode terminals 43 are located at the four corners (corner portions) of the second sealing member 4, respectively.

[0048] As shown in FIGS. 6 and 7 , the second sealing member 4 has four through holes formed therein that penetrate between the first main surface 411 and the second main surface 412. Specifically, the four sixth through holes 44 are provided in the four corner (corner) regions of the second sealing member 4. In the sixth through holes 44, through electrodes for ensuring electrical connection between the electrodes formed on the first main surface 411 and the second main surface 412 are formed along the inner wall surfaces of the sixth through holes 44. Furthermore, the central portions of each sixth through hole 44 form hollow through portions that penetrate between the first main surface 411 and the second main surface 412. Furthermore, in the first main surface 411 of the second sealing member 4, connection bonding patterns 45 are formed around each sixth through hole 44.

[0049] In the second sealing member 4, the external electrode terminal 43, the sealing-side second bonding pattern 421, and the connection bonding pattern 45 can be formed by the same process. Specifically, these can be formed from an underlayer formed by physical vapor deposition on the first and second main surfaces 411, 412 of the second sealing member 4, and a bonding film formed by physical vapor deposition on the underlayer. In this embodiment, Ti (or Cr) is used for the underlayer, and Au is used for the bonding film.

[0050] 1, an IC chip 5 (oscillator circuit element), which is an electronic component element, is bonded to the upper surface of the first sealing member 3 using metal bumps 38, and seven sealing plate connection electrodes 51a, 51b, 51c, 51d, 51e, 51f, and 51g are formed on the peripheral edge of the lower surface of the IC chip 5 at positions facing the electronic component element connection electrodes 37a, 37b, 37c, 37d, 37e, 37f, and 37g, respectively, as shown in Fig. 8. These sealing plate connection electrodes 51a to 51g of the IC chip 5 are bonded and electrically connected to the electronic component element connection electrodes 37a to 37g of the first sealing member 3 by the FCB method using the metal bumps 38.

[0051] 8, similarly to the electronic component element connecting electrode portions 37a-37g of the first sealing member 3, the sealing plate connecting electrode portions 51a-51g of the IC chip 5 are arranged at positions corresponding to the three corners of a rectangular region R (see FIG. 2) that includes the mounting pads of the IC chip 5 and is located inside the inner peripheral wall of the outer frame portion 23 of the piezoelectric diaphragm 2 in a plan view. The sealing plate connecting electrode portions 51b-51c are arranged offset in the directions B1 and B2 from the center of the long side on the A2 side of the rectangular region R. The sealing plate connecting electrode portions 51f-51e are arranged offset in the direction B2 from the center of the long side on the A1 side of the rectangular region R. The sealing plate connecting electrode portion 51e is arranged slightly offset in the direction A2 from the corner. Note that the closest distance between the sealing plate connecting electrode portions 51a-51g is preferably 0.2 mm or less.

[0052] Furthermore, similarly to the electronic component element connecting electrodes 37a to 37g, among the sealing plate connecting electrodes 51a to 51g, the sealing plate connecting electrode 51a and the sealing plate connecting electrode 51g, the sealing plate connecting electrode 51c and the sealing plate connecting electrode 51f, and the sealing plate connecting electrode 51d and the sealing plate connecting electrode 51e are arranged so as to align on the same line in the short side direction (A1-A2 direction) of the rectangular region R. Note that the sealing plate connecting electrodes of the IC chip 5 are not arranged on the line in the short side direction that passes through the centers of the two opposing long sides of the rectangular region R, and the same is true for the electronic component element connecting electrodes of the first sealing member 3.

[0053] In the piezoelectric vibration device 101 including the piezoelectric diaphragm 2, first sealing member 3, and second sealing member 4, the piezoelectric diaphragm 2 and the first sealing member 3 are diffusion-bonded with the first vibrating-side bonding pattern 251 and the first sealing-side bonding pattern 321 overlapping each other, and the piezoelectric diaphragm 2 and the second sealing member 4 are diffusion-bonded with the second vibrating-side bonding pattern 252 and the second sealing-side bonding pattern 421 overlapping each other, thereby producing the sandwich-structured package 12 shown in FIG. 1 . This hermetically seals the internal space of the package 12, i.e., the space housing the vibrating unit 22. At this time, the connecting bonding patterns are also diffusion-bonded with each other overlapping each other.

[0054] By joining the connection bonding patterns together, electrical conduction is achieved between the first excitation electrode 221, the second excitation electrode 222, the IC chip 5, and the external electrode terminal 43 in the piezoelectric vibration device 101.

[0055] Specifically, the first excitation electrode 221 is connected to the IC chip 5 via the first escape wiring 223, the junction between the connection junction pattern 27 and the connection junction pattern 353, the wiring pattern 33, the connection junction pattern 351, the through electrode in the fourth through hole 323, and the electrode pattern 37, in that order. The second excitation electrode 222 is connected to the IC chip 5 via the second escape wiring 224, the connection junction pattern 28, the through electrode in the second through hole 262, the junction between the connection junction pattern 254 and the connection junction pattern 352, the through electrode in the fifth through hole 324, and the electrode pattern 37, in that order.

[0056] In addition, the IC chip 5 is connected to the external electrode terminal 43 via the electrode pattern 37, the through electrode in the third through hole 322, the joint between the connection junction pattern 34 and the connection junction pattern 253, the through electrode in the first through hole 261, the joint between the connection junction pattern 253 and the connection junction pattern 45, and the through electrode in the sixth through hole 44, in that order.

[0057] Incidentally, when the sealing plate connection electrode portions 51a to 51g of the IC chip 5 are joined to the electronic component element connection electrode portions 37a to 37g of the first sealing member 3 by the FCB method using metal bumps 38, the stress due to the pressure during joining is greatest in the central part of the long side of the rectangular region R (see Figure 2) in a plan view inside the inner peripheral wall of the outer frame portion 23 of the piezoelectric diaphragm 2, which includes the mounting pad of the IC chip 5.

[0058] In the first embodiment, neither the electronic component element connecting electrode portion nor the sealing plate connecting electrode portion is disposed on the line connecting the centers of the two opposing long sides of the rectangular region R, and bonding can be achieved at two or more locations on either side of the line connecting the centers of the two long sides of the rectangular region R, thereby dispersing and preventing concentration of stress due to pressing during bonding. Also, in the long side direction of the rectangular region R where deflection is greatest, the bonding strength of the metal bump is likely to weaken at the position of the lowest point of deflection (on the line connecting the centers of the two long sides), but since bonding is performed while avoiding the lowest point of deflection, it is possible to prevent the bonding strength of the metal bump from weakening.

[0059] Therefore, according to the first embodiment, when the seven sealing plate connecting electrode portions 51a to 51g and the electronic component element connecting electrode portions 37a to 37g are joined by the FCB method using metal bumps 38, the stress caused by the pressing force during joining can be dispersed, preventing the stress from concentrating on one part of the first sealing member 3, and preventing cracks in the first sealing member 3 and poor joining strength.

[0060] In addition, seven sealing plate connection electrode portions 51a to 51g of the IC chip 5 are formed on the peripheral portion, and sealing plate connection electrode portions 51a, 51d, and 51g are arranged at the three corners of the rectangular region R indicated by the dotted line in Figure 2, sealing plate connection electrode portions 51b and 51c are arranged shifted in the B1 and B2 directions from the center of the long side on the A2 side of the rectangular region R, and sealing plate connection electrode portions 51f and 51e are arranged shifted sequentially in the B2 direction from the center of the long side on the A1 side of the rectangular region R, thereby effectively dispersing stress due to pressure when bonding the IC chip 5 to the first sealing member 3 using metal bumps.

[0061] At this time, by forming sealing plate connecting electrode portions 51a, 51d, and 51g at the three corners of rectangular region R, it is possible to join at least one diagonal portion, which corresponds to the maximum width dimension of IC chip 5 when joined, and two points on the long and short sides, thereby suppressing displacement of first sealing member 3 above vibrating portion 22 of piezoelectric diaphragm 2. Furthermore, by forming sealing plate connecting electrode portions 51b, 51c, and 51f at two or more points in the center of the long sides of rectangular region R, it is possible to suppress the amount of deflection of the long sides of rectangular region R and thereby suppress deflection of first sealing member 3 above vibrating portion 22 of piezoelectric diaphragm 2.

[0062] Furthermore, the outer frame portion 23 of the piezoelectric diaphragm 2 is formed so that the width of the portion corresponding to the short side of the rectangle of the piezoelectric diaphragm 2 is larger than the portion corresponding to the long side. Therefore, the sealing plate connection electrode portions 51a to 51g of the IC chip 5 and the electronic component element connection electrode portions 37a to 37g of the first sealing member 3 can be joined at a position close to the short side portion of the outer frame portion 23 of the piezoelectric diaphragm 2, which is wider and stronger than the long side, thereby reliably preventing cracking of the first sealing member 3 due to the stress of pressure during joining.

[0063] Furthermore, the electrode portions 37a and 37g, 37c and 37f, and 37d and 37e for connecting electronic component elements of the first sealing member 3, and the electrode portions 51a and 51g, 51c and 51f, and 51d and 51e for connecting sealing plates of the IC chip 5 are arranged side by side on the same line in the short side direction (A1-A2 direction) of the rectangular region R shown by the dotted line in Figure 2, so that the stress caused by the pressing force during joining can be distributed evenly at multiple linear positions in the short side direction of the rectangular region R.

[0064] Furthermore, since the electrode portion for connecting the sealing plate of the IC chip 5 and the electrode portion for connecting the electronic component element of the first sealing member 3 are not positioned on the line passing through the centers of the opposing long sides of the rectangular region R, the metal bump 38 is not bonded at a position on the line passing through the centers of the opposing long sides of the rectangular region R, which is the lowest point of deflection due to pressing during bonding, and this prevents the bonding strength of the metal bump 38 from weakening.

[0065] Furthermore, since the electrode portions 37a to 37g for connecting electronic component elements are positioned near the third, fourth and fifth through holes 322, 323 and 324 of the first sealing member 3, the third, fourth and fifth through holes 322, 323 and 324 of the first sealing member 3 can be used to relieve stress caused by pressing during bonding, thereby enhancing the stress dispersion effect.

[0066] Furthermore, as described above, the electrode portions 37d for connecting electronic component elements of the first sealing member 3 do not have an electrical connection function and only have a mechanical joining function with the metal bumps 38, so that it is possible to avoid overcrowding of the electrode portions for connecting electronic component elements, effectively suppress deflection in the rectangular region inside the inner wall of the outer frame portion 23 of the piezoelectric vibration plate 2, and prevent cracking of the first sealing member 3.

[0067] Furthermore, by positioning the electronic component element connecting electrode portions 37a-37g of the first sealing member 3 inside the rectangular region R in a plan view, it becomes possible to mount a smaller IC chip (electronic component element) 5. This allows for the miniaturization of the piezoelectric vibration device. Furthermore, mounting a small IC chip 5 is expected to expose and make visible the electrode pattern 37 formed in a position overlapping the outer frame portion 23 of the piezoelectric vibration plate 2, making it easier to measure by reliably contacting the measurement terminal with this electrode pattern. Furthermore, by positioning the small IC chip inside the rectangular region R, the area of ​​the surrounding area is reliably secured, so that underfill or the like applied to the gap after mounting the IC chip does not overflow from the edge of the piezoelectric vibration device 101, and the application of the underfill can be stabilized.

[0068] Second Embodiment A piezoelectric vibration device according to a second embodiment of the present invention will be described in detail with reference to Fig. 9. The piezoelectric vibration device according to the second embodiment differs from the first embodiment in the arrangement of the electrode pattern 37 of the first sealing member 3 and the electrode portions for connecting electronic component elements, but the other configurations are the same as those of the first embodiment. Below, differences from the first embodiment will be described with reference to Figs. 1 to 8.

[0069] In the second embodiment, the electrode pattern 37, which was located in the lower left corner in a planar view in the first sealing member 3 of the piezoelectric vibration device 101 according to the first embodiment shown in Figure 2, is separated into two as shown in Figure 9, and one of them is connected to an electrode pattern on which an electrode portion 37d for connecting an electronic component element is arranged to form a single electrode pattern 371, and the other is an electrode pattern 372 on which an electrode portion 37e for connecting an electronic component element is arranged, which is different from the first embodiment.

[0070] In this case, the electrode portion 37e for connecting electronic component elements is arranged along one long side of the rectangular area R indicated by the dotted line in Figure 2, i.e., the rectangular area R that includes the mounting pad of the IC chip 5 and is inside the inner wall of the outer frame portion 23 of the piezoelectric vibration plate 2, and is in the form of a floating island that is not connected to anything, and furthermore, this electrode portion 37e for connecting electronic component elements is not used for electrical connection but is used only for mechanical connection.

[0071] Therefore, according to the second embodiment, the same effects as those of the first embodiment can be obtained, and in addition, the electrode portion 37e for connecting electronic component elements is formed as a floating island that is not electrically connected to anything and is used only for mechanical connection, so that the concentration of the electrode portions for connecting electronic component elements can be avoided, deflection in the rectangular area inside the inner wall of the outer frame portion 23 of the piezoelectric vibration plate 2 can be effectively suppressed, and cracking of the first sealing member 3 can be prevented.

[0072] Third Embodiment A piezoelectric vibration device according to a third embodiment of the present invention will be described in detail with reference to Figures 10 and 11. The piezoelectric vibration device according to the third embodiment differs from the first embodiment in the arrangement of the electrode pattern 37 of the first sealing member 3 and the electrodes for connecting electronic component elements, and in the arrangement of the electrodes for connecting the sealing plate of the IC chip 5, but is otherwise the same as the first embodiment. Below, differences from the first embodiment will be described with reference to Figures 1 to 8.

[0073] In the third embodiment, a rectangular electrode pattern 373 is formed on the line connecting the electronic component element connecting electrode portions 37f and 37g in the electrode pattern 37 of the first sealing member 3 of the piezoelectric vibrating device 101 of the first embodiment shown in Figure 2, where the electronic component element connecting electrode portion 37b is arranged, as shown in Figure 10, and a rectangular cutout portion 374 is provided around this electrode pattern 373 to electrically isolate the electrode pattern 373, and an eighth electronic component element connecting electrode portion 37h is arranged in the electrode pattern 373, and an eighth sealing plate connecting electrode portion 51h is arranged at a position opposite the electronic component element connecting electrode portion 37h of the IC chip 5, as shown in Figure 11, which is different from the first embodiment. In this case, the electrode portions 37d, 37h for connecting electronic component elements are formed on floating island-like electrode patterns 37, 373 that are not electrically connected to either, and the metal bumps 38 that join the electrode portions 37d, 37h for connecting electronic component elements and the electrode portions 51d, 51h for connecting sealing plate are used only for mechanical joining.

[0074] In this case, the eight electrode portions 37a to 37h for connecting electronic component elements of the first sealing member 3 are arranged inside a rectangular area R in a plan view inside the inner peripheral wall of the outer frame portion 23 of the piezoelectric diaphragm 2, including the mounting pads of the IC chip 5 shown by the dotted line in Figure 10, and the eight electrode portions 51a to 51h for connecting sealing plates of the IC chip 5 are arranged in a similar manner.

[0075] Furthermore, the electronic component element connecting electrode portions 37b, 37h and the sealing plate connecting electrode portions 51b, 51h are arranged side by side on the same line in the short side direction (A1-A2 direction) of the rectangular region R, and except for the electronic component element connecting electrode portions 37d, 37e and the sealing plate connecting electrode portions 51d, 51e, are arranged line-symmetrically with respect to a line in the long side direction connecting the centers of the opposing short sides of the rectangular region R. Note that the electronic component element connecting electrode portion 37e and the sealing plate connecting electrode portion 51e may be arranged at a corner of the rectangular region R, and all of the electronic component element connecting electrode portions 37a to 37h and the sealing plate connecting electrode portions 51a to 51h may be arranged line-symmetrically.

[0076] Therefore, according to the third embodiment, it is possible to obtain the same effect as in the first embodiment, and since eight electrode portions 37a to 37h for connecting electronic component elements and eight electrode portions 51a to 51h for connecting sealing plates are arranged on the first sealing member 3 and the IC chip 5, the stress caused by the pressing force during bonding can be distributed evenly at multiple linear positions in the short side direction of the rectangular region R in a plan view inside the inner wall of the outer frame portion 23 of the piezoelectric diaphragm 2, including the mounting pad of the IC chip 5, and cracking of the first sealing member 3 can be prevented.

[0077] Furthermore, the electrode portions 37d, 37h for connecting electronic component elements are formed as floating island-like electrode patterns 37, 373 that are not electrically connected to either, and the metal bumps 38 that join the electrode portions 37d, 37g for connecting electronic component elements to the electrode portions 51d, 51h for connecting sealing plate are used only for mechanical joining, with the remaining metal bumps 38 being used for electrical joining. Therefore, by arranging electrically non-functional connection points while securing the wiring to be connected to the IC chip 5, it is possible to have multiple connection points without increasing the area of ​​the wiring, which in turn distributes the stress when joining the IC chip 5 to the first sealing member 3 and prevents cracking of the first sealing member 3.

[0078] The present invention is not limited to the above-described configuration, and various design modifications can be made within the scope of the claims.

[0079] For example, the piezoelectric diaphragm 2 in the above-described embodiment is not limited to an AT-cut quartz crystal plate, but may also be an SC-cut quartz crystal plate or a tuning fork vibrator.

[0080] In the above embodiment, the electronic component element is an IC chip 5, which is an oscillator circuit element. The IC chip 5 can be a CMOS output oscillation IC, a differential output oscillation IC, a VCXO IC, a TCXO IC, or the like. The electronic component element is not limited to an IC chip, and may be another electronic component element such as a thermistor or a temperature sensor.

[0081] Furthermore, in the above-described first and second embodiments, a case has been described in which one electrode portion 37e for connecting an electronic component element is arranged and formed in a floating island shape, but two or more electrode portions for connecting an electronic component element may also be arranged in a floating island shape.

[0082] In addition, in the above-described embodiment, a through electrode formed inside a through hole was exemplified as the conductive path from the IC chip 5 to the external electrode terminal 43 of the second sealing member 4, but a so-called castellation, in which a recess such as a notch is formed on the external end surface of the piezoelectric vibration device (first sealing member, piezoelectric vibration plate, second sealing member) 101 and a side end electrode is formed on the surface of the recess, may also be used as the conductive path.

[0083] Furthermore, the shapes of the first and second excitation electrodes 221, 222 are not limited to the rectangular shapes shown in FIGS. 4 and 5, but may be circular or polygonal.

[0084] The present invention can be widely applied to piezoelectric vibration devices in which a piezoelectric vibration plate is hermetically sealed by upper and lower sealing plates that cover the upper and lower surfaces of the piezoelectric vibration plate, respectively, and electronic component elements are electrically and mechanically joined to the upper surface of the upper sealing plate by metal bumps. [Explanation of symbols]

[0085] 2...Piezoelectric diaphragm 3...First sealing member (upper sealing plate) 4...Second sealing member (lower sealing plate) 5...IC chips (electronic component elements) 22...Vibration part 23...Outer frame 24...Holding part 25...Cutout 37a to 37h ...Electrode parts for connecting electronic components 38...metal bump 51a to 51h ... Sealing plate connection electrode part 101...Piezoelectric vibration device 221...First excitation electrode 222...Second excitation electrode R…Rectangular area

Claims

1. A piezoelectric vibration device in which a piezoelectric vibration plate is hermetically sealed by an upper sealing plate and a lower sealing plate that cover the upper and lower surfaces of the piezoelectric vibration plate, and an electronic component element is electrically and mechanically bonded to the upper surface side of the upper sealing plate using metal bumps, The piezoelectric diaphragm has a substantially rectangular shape, a vibration section having a rectangular shape in plan view and on which a pair of excitation electrodes are formed; an outer frame portion having an inner peripheral wall that is rectangular in plan view and surrounds an outer peripheral wall of the vibration portion; a holding portion that connects the outer peripheral wall of the vibration portion and the inner peripheral wall of the outer frame portion; a cutout portion formed by cutting out the piezoelectric diaphragm in a plate thickness direction between the vibration portion and the outer frame portion, the outer frame portion is formed to be thicker than the vibration portion and the holding portion, The upper sealing plate is a rectangular shape substantially identical to that of the piezoelectric diaphragm, covering an upper surface of the piezoelectric diaphragm to seal the vibrating portion; The lower sealing plate is a rectangular shape substantially identical to that of the piezoelectric diaphragm, covering the lower surface of the piezoelectric diaphragm to seal the vibrating portion; The electronic component element is an area in a plan view that is smaller than those of the upper sealing plate and the lower sealing plate, and seven or more sealing plate connecting electrode portions are formed on the lower surface thereof; seven or more electronic component element connecting electrode portions to which the seven or more sealing plate connecting electrode portions are respectively connected are formed on an upper surface of the upper sealing plate that does not face the piezoelectric vibration plate, The metal bumps electrically connect the seven or more sealing plate connecting electrode portions of the electronic component element to the seven or more electronic component element connecting electrode portions of the upper sealing plate, respectively. A piezoelectric vibration device characterized by:

2. 2. The piezoelectric vibrating device according to claim 1, wherein the seven or more sealing plate connecting electrodes of the electronic component element are formed on a peripheral edge portion.

3. The seven or more sealing plate connecting electrode portions of the electronic component element are 2. The piezoelectric vibrating device according to claim 1, wherein the contact holes are formed at least at three corners of the electronic component element and at two or more locations in the center of a pair of long sides.

4. the seven or more electronic component element connecting electrode portions of the upper sealing plate are formed in a rectangular region in plan view inside an inner peripheral wall of the outer frame portion of the piezoelectric diaphragm, One or more of the electronic component element connecting electrodes along one long side of the rectangular region are formed in a floating island shape that is not connected to anything.

4. The piezoelectric vibration device according to claim 1, wherein the piezoelectric vibration device is a piezoelectric vibrating device.

5. A piezoelectric vibration device as described in any one of claims 1 to 3, or claim 4 dependent on claim 1, characterized in that the width of the part of the outer frame portion of the piezoelectric vibration plate corresponding to the short side of the rectangle is larger than the width of the part corresponding to the long side.

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