JP5239784B2 - Piezoelectric vibration device - Google Patents

Description

  The present invention relates to a piezoelectric vibration device used for electronic equipment and the like.

  In recent years, miniaturization and thinning of various electronic devices are rapidly progressing, and accordingly, piezoelectric vibration devices (for example, crystal resonators) are required to be ultra-miniaturized. However, for example, in the case of a piezoelectric vibration device in which a piezoelectric vibration plate is mounted inside a conventional ceramic container body and hermetically sealed with a lid body, it is necessary to cope with ultra-miniaturization due to the problem of molding accuracy of the container body. Has become difficult. On the other hand, the container body and the cover body are made of, for example, crystal or glass, and the container is formed on both main surfaces of the piezoelectric diaphragm so as to seal the excitation electrodes formed on both main surfaces of the piezoelectric diaphragm. There is a piezoelectric vibration device that joins a body and a lid (see, for example, Patent Document 1 and Patent Document 2 below). In the manufacture of such a piezoelectric vibration device, for example, any member of a piezoelectric vibration plate, a container body, and a lid body is handled by a substrate formed by connecting a plurality of elements, thereby simplifying the handling and improving the production efficiency. I try to improve.

Japanese Patent No. 3390348 JP 2001-119264 A

  In addition, with the recent increase in operating frequency of various electronic devices, piezoelectric vibration devices are also required to support higher frequencies. For example, when an AT-cut quartz plate is used as the piezoelectric diaphragm, the thickness thereof is inversely proportional to the frequency, so that it becomes very thin in the high frequency band. In this way, when the thickness of the quartz plate becomes very thin, it becomes mechanically fragile. Therefore, the mechanical strength of the quartz plate is obtained by integrally forming a reinforcing portion thicker than the thin region around the thin region. In general, a structure that enhances the so-called “reverse mesa structure” is used.

  In Patent Document 1 and Patent Document 2 described above, a lid (lid member) is joined to each of the outer peripheral portions of the front and back main surfaces of the piezoelectric diaphragm via a metal film. A quartz plate is used as the piezoelectric diaphragm, and a so-called inverted mesa structure is disclosed. In such a structure, the crystal plate and the upper and lower lids are joined by melting the metal film. However, in the above structure, stress such as shrinkage stress of the metal film after the bonding propagates from the outer peripheral part (thick part) of the quartz plate to the inner part (thin part), and the oscillation frequency of the piezoelectric vibration device is caused by the stress. There is concern about changes. The stress also adversely affects various characteristics of the piezoelectric vibration device. Further, in Patent Document 1 and Patent Document 2 described above, the bonding material (metal film) that contributes to the bonding of the piezoelectric diaphragm and the upper and lower lids thereof, and the external connection of the excitation electrode and the bottom surface of the piezoelectric vibration device are electrically connected. Electrodes for connection (abbreviated as connection electrodes) are formed in the vicinity of the outer periphery of each member. In such a close state, for example, when the bonding material is heated and melted, the molten metal flows out toward the inner side of the piezoelectric vibration device (or the molten metal at the time of forming the connection electrode flows toward the outer side of the piezoelectric vibration device), The bonding material and the connection electrode come into contact with each other, increasing the risk of causing an insulation failure.

  The present invention has been made in view of the above points, and provides a piezoelectric vibration device capable of preventing insulation failure and obtaining stable characteristics while relaxing stress generated in the piezoelectric diaphragm. It is the purpose.

In order to achieve the above object, the invention of claim 1 is characterized in that a piezoelectric diaphragm having a pair of front and back excitation electrodes and a front and back outer periphery of the piezoelectric diaphragm are bonded to each other via a bonding material, and the excitation electrodes are hermetically sealed. A piezoelectric vibration device configured with a lid member to be stopped, wherein the piezoelectric vibration plate surrounds the vibration part on which an excitation electrode is formed and is thicker than the vibration part. A thin portion or a through portion formed thinner than the vibrating portion or a combined configuration of the thin portion and the penetrating portion is integrally formed between the frame portion and the vibrating portion and the frame portion, and the vibration A protrusion made of the same material as that of the vibration portion is formed integrally with the vibration portion on at least one main surface of the front and back main surfaces of the vibration portion. A first bonding electrode drawn out to the side is formed, and the protrusion is formed of the protrusion Is formed to a thickness upper surface of the one main surface substantially flush with the frame portion is, in the one main surface of one of the lid member, the external connection terminal electrically formed on the other main surface of the lid member The second bonding electrode connected to the first bonding electrode is formed, and the first bonding electrode and the second bonding electrode are integrally bonded via the metal brazing material, so that the excitation electrode is electrically connected to the external connection terminal. Yes. With the piezoelectric vibration device having such a structure, various stresses generated in the piezoelectric vibration member after bonding can be effectively relieved.

  Specifically, when the lid members are bonded to the front and back outer peripheral portions of the piezoelectric vibrating body via the bonding material, various stresses (such as shrinkage stress of the bonding material) generated by the bonding can be relieved by the thin portion. . Further, the through portion may be formed without forming the thin portion between the vibrating portion and the frame portion. By forming the penetrating portion, the various stresses described above can be relaxed. Furthermore, you may form both a thin part and a penetration part between a vibration part and a frame part. With the above structure, the stress propagating to the vibration part where the excitation electrode is formed is relieved, and a change in the oscillation frequency of the piezoelectric vibration device can be suppressed. In addition, due to the stress relaxation, it is possible to prevent deterioration of the characteristics of the piezoelectric vibrating device.

  In addition, according to the above configuration, the conduction path (the first joint electrode and the second joint electrode etc. that are integrally joined via the metal brazing material) for electrically connecting the excitation electrode and the external connection terminal, It is formed at a position separated from the frame portion, that is, at the vibration portion. Thus, when the metal film (metal brazing material) is heated and melted to form the conduction path, the thin portion functions as a “groove” even if the molten metal moves outward of the piezoelectric vibrating device. The molten metal can be retained in the thin part. Thereby, it is possible to prevent insulation failure caused by contact with the bonding material formed in the outer peripheral region of the piezoelectric vibration device and the conduction path.

In order to achieve the above object, according to the first aspect of the present invention, at least one main surface of the front and back main surfaces of the vibration portion has a protrusion made of the same material as that of the vibration portion. The protrusion is formed with the first bonding electrode, and the protrusion has a thickness such that the upper surface of the protrusion is substantially flush with one main surface of the frame. Yes.

  According to the said structure, the thickness (height) of the said projection part is formed in the thickness (height) used as the substantially same plane as the one main surface of the said frame part. Thereby, for example, when the upper surface of the bonding material formed on the frame portion and the upper surface of the metal film (metal brazing material) formed on the projection portion are formed substantially aligned by an electrolytic plating method, the film thickness can be easily managed. be able to. That is, film formation by electrolytic plating of the bonding material on the outer periphery of the main surface of the frame portion and the metal film on the protrusion can be performed simultaneously. When the one principal surface of the frame portion and the one principal surface of the vibration portion are non-identical, the upper surface of the bonding material of the frame portion and the upper surface of the metal film on the protrusion portion are substantially aligned. Therefore, since the thicknesses of the bonding material and the metal film formed on the frame portion and the projection portion are different, the film thickness management for controlling the substantially same plane becomes complicated. Compared with this, if it is the structure of this invention, a film thickness can be managed by collective electrolytic plating. Moreover, since the thickness (height) of the protrusion is formed with a thickness (height) that is substantially flush with one main surface of the frame, the amount of metal used can also be reduced.

In order to achieve the above object, according to the invention of claim 2 , the piezoelectric diaphragm is made of an AT-cut quartz plate having a rectangular shape in plan view, the long side of the piezoelectric diaphragm is the X axis, and the piezoelectric diaphragm When the Z ′ axis is the short side of the thin wall portion, a through-hole is formed in a partial region in the Z′-axis direction of the thin-walled region, and a wall conductor connecting the upper end and the lower end of the through-portion, The excitation electrode on one main surface side of the vibrating portion is partially attached to the inner wall surface of the penetrating portion, and is routed to the other main surface side via the wall surface conductor, and is electrically connected to the first joint electrode. Connected.

  When the thin-walled portion is formed by wet etching (chemical dissolution) using a quartz crystal plate, the quartz crystal is an anisotropic crystal, and therefore the erosion angle in the crystal depth direction varies depending on the axial direction. . That is, due to the difference in the erosion angle, a difference occurs in the opening angle of the melted portion. Specifically, since the erosion angle in the crystal depth direction is larger in the Z′-axis direction than in the X-axis direction, the opening angle becomes larger. Due to the difference in the opening angle, the mechanical strength of the thin portion after etching is inferior in the X-axis direction to the Z′-axis direction. However, according to the structure of the present invention, a through hole is formed in a partial region in the Z′-axis direction, and the X-axis direction is connected to the frame portion and the vibration portion with a thin portion as a boundary. That is, by setting the X-axis direction as the long side direction of the crystal diaphragm, it is possible to suppress a decrease in the strength of the crystal diaphragm compared to the case where the penetrating portion is formed in the X-axis direction.

  On the other hand, when the through hole is formed by wet etching from either the front or back side (for example, the front side) of the quartz plate, the quartz is an anisotropic crystal. The shape of the erosion hole almost approaches an inverted triangular pyramid shape. That is, the through hole has a difference in opening size between the front and back sides. This is because the difference in the opening dimension becomes more apparent as it approaches a low frequency band that is thicker than a high-frequency band quartz plate (the thickness of an AT-cut quartz plate is inversely proportional to the frequency). Therefore, in order to ensure a sufficient hole diameter for filling the through hole with a conductor and to ensure the vertical connection of the through hole, at least to one principal surface side of the crystal due to the anisotropy of the crystal An opening area having a size of 2 mm is required. That is, securing the opening area leads to a decrease in the vibration area. However, according to the structure of the present invention, a through-hole is formed in a partial region in the Z′-axis direction of the thin-walled region, and a wall surface conductor connecting the upper end and the lower end of the through-portion is formed on the through-hole. It is partially attached to the inner wall surface. That is, by passing through the wall conductor, it is possible to ensure conduction from one main surface side to the other main surface side of the vibrating portion without forming a through hole. Therefore, it is possible to ensure a wide vibration region as compared with the structure in which the through hole is formed. Thereby, the design freedom of a piezoelectric vibration device can be increased.

  As described above, according to the present invention, the present invention has been made in view of such a point, and while suppressing stress generated in the piezoelectric diaphragm, it prevents insulation failure and obtains stable characteristics. A piezoelectric vibration device that can be provided can be provided.

-First embodiment-
Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, a case where a crystal resonator is applied to the present invention as a piezoelectric vibration device is shown. FIG. 1 is a schematic cross-sectional view in the long side direction of a crystal resonator showing a first embodiment of the present invention, and FIG. 2 is an exploded view of each member in FIG. Hereinafter, first, main components of the crystal resonator will be described, and then a manufacturing method thereof will be described.

  As shown in FIG. 1, the crystal resonator 1 according to the present embodiment includes a crystal diaphragm 2 (a piezoelectric diaphragm in the present invention) and an excitation electrode 23 formed on one main surface 21 of the crystal diaphragm 2. The first lid member 3 that hermetically seals and the second lid member 4 that hermetically seals the excitation electrode 23 formed on the other main surface 22 of the crystal diaphragm 2 are main constituent members. In the crystal resonator 1, the crystal diaphragm 2 and the first lid member 3 are joined by the joining material 5, and the crystal diaphragm 2 and the second lid member 4 are joined by the joining material 5, thereby forming the package 11. Is done. Then, the first lid member 3 and the second lid member 4 are joined to each other through the crystal diaphragm 2, thereby forming two internal spaces 12 of the package 11, and crystal vibrations in the internal space 12 of the package 11. Excitation electrodes 23 formed on both main surfaces 21 and 22 of the plate 2 are hermetically sealed in the respective internal spaces 12. The first lid member and the second lid member have substantially the same shape and substantially the same outer dimensions, and the first lid member 3 has an external formed on the bottom surface (other main surface) 37 of the lid member. A conduction path (via) 35 electrically connected to the connection terminal 34 is formed penetrating in the thickness direction of the lid member.

  In FIG. 2, a quartz crystal plate 2 is an AT-cut quartz plate cut out at a predetermined angle. The crystal diaphragm 2 has a vibration part 20 on which an excitation electrode 23 is formed, a frame part 29 and a thin part 28, which are integrally formed. Here, the frame part 29 surrounds the vibration part 20 in an annular shape and is formed thicker than the vibration part. The thin portion 28 is formed between the vibrating portion 20 and the frame portion 29 and is formed thinner than the vibrating portion (bank portion 27). In the present invention, the vibrating part is not limited to the region where the excitation electrode is formed. In the description of the present embodiment, the “vibrating part” is a thin part formed inside the frame part or a region inside the through hole (specifically, the concave part 26 and the bank part 27). In the present embodiment, the vibration unit 20 includes a concave portion 26 in which the excitation electrode 23 is formed on the front and back sides, and a bank portion 27 that surrounds the concave portion 26 in a ring shape (a so-called “reverse mesa” -shaped vibration portion. ing). In addition, the structure of the vibration part 20 is not limited to the said structure, A flat plate shape may be sufficient. In the present embodiment, the thin portion is formed on the outer periphery of the “reverse mesa” -shaped vibrating portion, but the thin portion is not formed in the inner region of the frame portion, and the through portion is partially formed as a flat plate. It may be formed automatically. In these structures as well, the thickness of the vibration part is thinner than that of the frame part.

  The concave portion 26, the bank portion 27, and the thin portion 28 are formed by wet etching. Excitation electrodes 23 are formed opposite to each other on the front and back surfaces (one main surface 21 and the other main surface 22) of the recess 26 by vapor deposition. In the present embodiment, the excitation electrode 23 is formed on the front and back main surfaces of the crystal diaphragm 2 in order from the bottom in a chromium and gold film configuration. The film configuration of the electrode is not limited to this, and other film configurations may be used. An extraction electrode 24 is led out from the excitation electrode 23, and the extraction electrode 24 extracted from the other main surface 22 penetrates the vibration portion in the thickness direction from the boundary portion between the recess 26 and the bank portion 27, and has one main surface. 21 side. A first bonding electrode 25 is formed at the terminal portion of the extraction electrode 24. A gold (Au) plating layer 50 is formed on the first bonding electrode 25.

  Both main surfaces 21 and 22 of the crystal diaphragm 2 have a mirror finish and are formed as flat smooth surfaces. In the crystal diaphragm 2, both main surfaces 201 and 202 of the frame portion 29 are configured as a joint surface between the first lid member 3 and the second lid member 4, and the vibration portion 20 is configured as a vibration region. A first bonding material 51 for bonding to the first lid member 3 is formed on one main surface 201 of the frame portion 29. A second bonding material 52 for bonding to the second lid member 4 is formed on one main surface 201 of the frame portion 29. Here, the formation widths of the first bonding material 51 and the second bonding material 52 are substantially the same. The first bonding material 51 and the second bonding material 52 have the same configuration. The first bonding material 51 and the second bonding material 52 are configured by laminating a plurality of layers on both main surfaces 201 and 202 of the frame portion 29. In the present embodiment, the first bonding material and the second bonding material are formed by forming a chromium (Cr) layer (not shown) and a gold (Au) layer (not shown) from the lowermost layer side by vapor deposition. A gold plating layer (not shown) is laminated by an electrolytic plating method.

  In FIG. 2, the first lid member 3 is a flat plate having a rectangular shape in plan view, and a Z-plate crystal is used. In plan view, the outer dimensions of the first lid member 3 are substantially the same as the outer dimensions of the crystal diaphragm 2, and one main surface 31 of the first lid member 3 (joint surface 32 with the crystal diaphragm 2 described below). Is formed as a flat smooth surface (mirror finish). A third bonding material 53 is formed in a circumferential shape on the periphery of the first lid member 3 on the side of the bonding surface with the crystal diaphragm 2. Here, the formation width of the third bonding material 53 is formed to be substantially the same as the formation width of the first bonding material 51.

  The first lid member 3 includes a second bonding electrode 33 bonded to the first bonding electrode 25 of the crystal vibrating plate 2 via a metal film (metal brazing material), and a bonding portion (specifically) bonded to the crystal vibrating plate 2. In particular, a joint surface 32) and an external connection terminal 34 electrically connected to the outside are provided. The joint surface 32 with the crystal diaphragm 2 is provided on the outer periphery of the main surface 31 of the first lid member 3 in plan view.

  On the bonding surface 32 of the first lid member 3, a third bonding material 53 for bonding to the crystal diaphragm 2 is formed. Specifically, a plurality of layers of the third bonding material 53 are laminated on the bonding surface 32, and a chromium (Cr) layer (not shown) and a gold (Au) layer 531 are formed by vapor deposition from the lowermost layer side. An Au—Sn alloy layer 532 is formed on the substrate, and an Au flash plating layer 533 is formed thereon. Alternatively, the third bonding material 53 may be formed by vapor-depositing a Cr layer and an Au layer from the lower surface side, and sequentially laminating an Sn plating layer and an Au plating layer thereon. The third bonding material 53 and the second bonding electrode 33 are formed at the same time, and the second bonding electrode 33 has the same configuration as the third bonding material 53. Further, as shown in FIG. 2, the first lid member 3 is formed with a through hole 35 for electrically connecting the excitation electrode 23 of the crystal diaphragm 2 to the outside. Then, an electrode pattern 36 is formed through the through hole 35 from the second joint electrode 33 on the one principal surface 31 of the first lid member 3 to the external connection terminal 34 on the other principal surface 37 of the first lid member 3. ing.

  In FIG. 2, the second lid member 4 is a flat plate having a rectangular shape in plan view, and a Z-plate crystal is used similarly to the first lid member 3. The external dimensions of the second lid member 4 in plan view are substantially the same as the external dimensions of the crystal diaphragm 2. One main surface 41 of the second lid member 4 (a bonding surface 42 with the crystal diaphragm 2 described below) is formed as a flat smooth surface (mirror finish). A fourth bonding material 54 is formed on the periphery of the second lid member 4 on the side of the bonding surface with the crystal diaphragm 2. Here, the formation width of the fourth bonding material 54 is substantially the same as the formation width of the second bonding material 52.

  The second lid member 4 is provided with a joint portion (specifically, a joint surface 42) that joins the crystal diaphragm 2. The joint surface 42 is provided on the outer periphery of the main surface 41 of the second lid member 4 in plan view. A fourth bonding material 54 for bonding to the crystal diaphragm 2 is formed on the bonding surface 42 of the second lid member 4. Specifically, in the fourth bonding material 54, a plurality of layers are laminated on the bonding surface 42, a Cr layer (not shown) and an Au layer 541 are formed by vapor deposition from the lowermost layer side, and an Au—Sn alloy is formed thereon. The layer 542 is laminated and formed, and the Au flash plating layer 543 is laminated thereon. Alternatively, the fourth bonding material 54 may be formed by vapor-depositing a Cr layer and an Au layer from the lower surface side, and sequentially laminating an Sn plating layer and an Au plating layer thereon.

  Bonding of the bonding region (seal path) of the first bonding material 51 on the bonding surface (one main surface 201 of the frame portion 29) of the crystal vibrating plate 2 and bonding of the third bonding material 53 on the bonding surface 32 of the first lid member 3. The region (seal path) has the same width. Further, the bonding region (seal path) of the second bonding material 52 on the bonding surface (the other main surface 202 of the frame portion 29) of the crystal diaphragm 2 and the bonding of the fourth bonding material 54 on the bonding surface 42 of the second lid member 3. The region (seal path) has the same width. The above is the description of the main members constituting the crystal unit 1.

  Next, a manufacturing method of the crystal unit 1 will be described with reference to FIG. In the present embodiment, the quartz crystal diaphragm 2 in a state where a large number of pieces are collectively formed on the wafer is arranged on the first lid member 3 in the individual piece state, and the second lid member 4 in the individual piece state is further provided thereon. A manufacturing method for separating a wafer (quartz crystal plate) into a large number of crystal units by dicing will be described. However, the present invention is not limited to the method described in the present embodiment, and a large number of crystal wafers are collectively formed on the first lid member 3 in a state where a large number of wafers are collectively formed. The quartz crystal plate 2 in a state of being placed is disposed, and a plurality of second lid members 4 are formed on the wafer, and the quartz plate 2, the first lid member 3 and the second lid member are disposed thereon. 4 may be used, followed by singulation. In this case, the crystal resonator 1 is suitable for mass production.

  First, a large number of first lid members 3 are stored in a pallet (not shown). The pallet has a predetermined interval between the adjacent first lid members 3 and is designed so that the first lid members can be aligned and accommodated at a constant interval. Then, the main surface 21 of the crystal diaphragm 2 is the main surface of the first lid member 3 on the main surface 31 of the first lid member 3 at the position where the crystal resonator plate 2 in the wafer state is set by the image recognition means. It arrange | positions so that the surface 31 may be opposed. At this time, the third bonding material 53 formed on the bonding surface 32 of the first lid member 3 and the first bonding material 51 formed on the one main surface 201 of the frame portion 29 of the crystal diaphragm 2 are viewed in a plan view. They are arranged so that they are almost identical. In addition, the second bonding electrode 33 formed on the one main surface 31 of the first lid member 3 and the gold plating layer 50 formed on the first bonding electrode 25 of the quartz crystal vibration plate 2 are substantially the same in a plan view. They are arranged to match.

  After the quartz diaphragm 2 is arranged on the first lid member 3, the second lid member 4 in the individual state is placed on the other main surface 22 of the quartz diaphragm 2 at the position set by the image recognition means. 4 are laminated so that one principal surface 41 faces the other principal surface 22 of the crystal diaphragm 2. At this time, the second bonding material 52 formed on the other main surface 202 of the frame portion 29 of the crystal diaphragm 2 and the fourth bonding material 54 formed on the bonding surface 42 of the second lid member 4 are viewed in plan view. They are arranged so that they are almost identical.

  After laminating the first lid member 3, the crystal diaphragm 2 and the second lid member 4, the ultrasonic waves of the first lid member 3, the quartz diaphragm 2 and the second lid member 4 are bonded by using ultrasonic waves. Temporary joining is performed. After temporarily bonding the first lid member 3, the crystal diaphragm 2, and the second lid member 4, other manufacturing processes (such as degassing the internal space 12 and adjusting the oscillation frequency) are performed, followed by heating and melting. Join. In the present embodiment, the first lid member 3, the crystal diaphragm 2 and the second lid member 4 are joined in a vacuum atmosphere. However, the present invention is not limited to this, and an inert gas such as nitrogen is used. May be used.

  Next, the first lid member 3, the crystal diaphragm 2, and the second lid member 4 that are temporarily joined are placed in an environment where the temperature is raised to a predetermined temperature, and each joining material formed on each member is melted. This is the main joining. Specifically, the bonding material 5 is configured by bonding the first bonding material 51 and the third bonding material 53, and the crystal vibrating plate 2 and the first lid member 3 are bonded by the bonding material 5. As shown in FIG. 1, the excitation electrode 23 formed on one main surface 21 of the quartz crystal plate 2 is hermetically sealed by joining the crystal plate 2 and the first lid member 3 with the bonding material 5. Also, the bonding material 5 is formed by performing heat-melt bonding simultaneously with the bonding of the first bonding material 51 and the third bonding material 53 and bonding the second bonding material 52 and the fourth bonding material 54. The crystal diaphragm 2 and the second lid member 4 are joined by the material 5. As shown in FIG. 1, the excitation electrode 23 formed on the other main surface 22 of the crystal vibrating plate 2 is hermetically sealed by bonding the crystal vibrating plate 2 and the second lid member 4 with the bonding material 5.

  As described above, according to the crystal resonator 1 according to the present embodiment, various stresses generated in the crystal resonator plate 2 after bonding can be effectively relaxed. Specifically, when the lid members 3 and 4 are joined to the front and back outer peripheral parts of the crystal resonator plate via the joining material, various stresses (such as shrinkage stress of the joining material) generated by the joining are relieved by the thin portion 28. can do. Thereby, the stress which propagates to the vibration part 20 with which the excitation electrode 23 was formed is relieved, and the change of the oscillation frequency of a crystal oscillator can be suppressed. Further, the stress relaxation can prevent the characteristic deterioration of the crystal resonator.

  Further, according to the crystal resonator 1 according to the present embodiment, the conductive path (the first bonding electrode and the first bonding electrode that are integrally bonded via the metal brazing material and the first bonding electrode) are electrically connected to the excitation electrode 23 and the external connection terminal 34. 2 junction electrodes and the like) are formed at positions separated from the frame portion 29, that is, at the vibration portion 20. As a result, when the metal film (metal brazing material) is heated and melted to form the conduction path, the thin portion 28 functions as a “groove” even if the molten metal moves to the outside of the crystal resonator. The molten metal can be retained in the thin part. Thereby, it is possible to prevent insulation failure caused by contact with the bonding material formed in the outer peripheral region of the piezoelectric vibration device and the conduction path.

  In the present embodiment, the vibration part 20 has a reverse mesa shape in which a bank part 27 is formed on the outer periphery of the recess 26, and has a structure in which a thin part 28 is formed outside the vibration part 20. However, the present invention is not limited to the above structure. For example, as shown in the modification of the first embodiment in FIG. 3, a shape in which the thin portion is not formed, the inside of the frame portion is a flat plate, and a through hole is partially provided may be used.

  In the embodiment of the present invention, Cr, Au, and Sn are used as the bonding material 5. However, the present invention is not limited to this, and the bonding material 5 may be composed of, for example, Cr, Au, and Ge. Good. Also, a plated laminated film such as Au and Sn or a plated alloy layer such as AuSn may be formed on the piezoelectric diaphragm side, and an Au plated layer (single metal element plated layer) may be formed on the lid member side. Furthermore, in the embodiment of the present invention, quartz is used as the material for the two package substrates, but glass or sapphire may be used in addition to quartz.

-Second Embodiment-
A second embodiment of the present embodiment will be described with reference to FIGS. 4 to 6 by taking as an example a crystal resonator using a crystal diaphragm as a piezoelectric diaphragm as in the first embodiment. FIG. 4 is a plan view of a crystal diaphragm showing a second embodiment of the present invention. FIG. 5 is a schematic cross-sectional view in the long side direction of a quartz crystal diaphragm showing a second embodiment of the present invention, and FIG. 6 is an enlarged perspective view of a portion A in FIG. In addition, about the structure similar to 1st Embodiment, while attaching | subjecting the same number and omitting a part of description, it has an effect similar to the above-mentioned embodiment. Hereinafter, a description will be given focusing on differences from the first embodiment.

  As shown in FIG. 4, in the present embodiment, two through portions 6 are formed in the thin portion 28 of the crystal diaphragm 2. The penetrating portion 6 is formed in a partial region in the Z′-axis direction in the region of the thin portion 28. In this way, by forming the penetrating portions on both sides of the vibrating portion, various stresses such as shrinkage stress after curing of the bonding material between the quartz crystal plate and the lid member are applied to the thin-walled portion 28 and further effectively dispersed. Can do.

  When a thin-walled portion is formed by wet etching (chemical dissolution) using a quartz diaphragm, the quartz is an anisotropic crystal, and therefore the erosion angle in the depth direction of the quartz varies depending on the difference in the axial direction. That is, due to the difference in the erosion angle, a difference occurs in the opening angle of the melted portion. Specifically, since the erosion angle in the crystal depth direction is larger in the Z′-axis direction than in the X-axis direction, the opening angle becomes larger. Due to the difference in the opening angle, the mechanical strength of the thin portion after etching is inferior in the X-axis direction to the Z′-axis direction. However, according to the structure of the present invention, a through hole is formed in a partial region in the Z′-axis direction, and the X-axis direction is connected to the frame portion and the vibration portion with a thin portion as a boundary. That is, by setting the X-axis direction as the long side direction of the crystal diaphragm, it is possible to suppress a decrease in the strength of the crystal diaphragm compared to the case where the penetrating portion is formed in the X-axis direction.

  4 to 5, the vibration part 20 has a rectangular plate shape in plan view, and a pair of protrusions 8 are formed near both ends of one short side. The protrusion 8 is integrally formed of the same material as that of the vibration part, and the thickness (height) thereof is formed with a thickness (height) that is substantially flush with the one main surface 201 of the frame part 29. . The protrusion 8 is connected to the extraction electrode 24 extracted from the excitation electrode 23, and the surface of the protrusion 8 is covered with the first bonding electrode. The first junction electrode is made of the same material and the same film configuration as the extraction electrode and the excitation electrode.

  According to the crystal resonator 1 according to the present embodiment, the thickness (height) of the protrusion 8 is formed with a thickness (height) that is substantially flush with one main surface of the frame portion 29. Thereby, for example, when the upper surface of the bonding material formed on the frame portion and the upper surface of the metal film (metal brazing material) formed on the projection portion are formed substantially aligned by an electrolytic plating method, the film thickness can be easily managed. be able to. That is, film formation by electrolytic plating of the bonding material on the outer periphery of the main surface of the frame portion 29 and the metal film on the protruding portion 8 can be performed simultaneously. When the one principal surface of the frame portion and the one principal surface of the vibration portion are non-identical, the upper surface of the bonding material of the frame portion and the upper surface of the metal film on the protrusion portion are substantially aligned. Therefore, since the thicknesses of the bonding material and the metal film formed on the frame portion and the projection portion are different, the film thickness management for controlling the substantially same plane becomes complicated. Compared with this, if it is the structure of this invention, a film thickness can be managed by collective electrolytic plating. Moreover, since the thickness (height) of the protrusion is formed with a thickness (height) that is substantially flush with one main surface of the frame, the amount of metal used can also be reduced.

  FIG. 6 is an enlarged perspective view of a portion A in FIG. 4 and is a view showing a part of the frame portion removed so that the inner wall surface of the penetrating portion can be seen. The penetrating portion 6 is formed by wet etching from both the front and back sides of the crystal diaphragm, and a wall conductor 7 is partially attached to the inner wall surface of the penetrating portion 6. Specifically, the wall surface conductor 7 is formed in the thin-walled region 61 in the inner wall surface of the penetrating portion 6, and the side surface portion 62 of the vibrating portion is in a state where the quartz substrate is exposed. The wall conductor 7 first forms the penetrating portion 6 and then deposits a metal film made of the same material and the same film structure as the excitation electrode on the entire inner wall surface of the penetrating portion by vapor deposition. Next, a resist is formed in the thin-walled region 61, and exposure and development are performed. Then, the wall conductor 7 is formed by removing the metal etching and the resist.

  The excitation electrode 23 on the other main surface 22 side (the lower surface side of the vibrating portion 20 in FIG. 6) passes through the lead electrode 24 on the other main surface side and passes through the wall conductor 7 connected to the other main surface 21 side (FIG. 6 is connected to the first bonding electrode on the upper surface side of the vibration unit 20. The first bonding electrode is integrally bonded to the second bonding electrode 33 formed on the other main surface 31 of the first lid member 3 through the metal brazing material as described above in the first embodiment. As a result, the external connection terminal 34 formed on the other main surface 37 of the first lid member 3 is finally electrically connected.

  When a through-hole is formed in a quartz plate by wet etching from either the front or back (for example, the front side), the quartz is an anisotropic crystal, so the deeper the etching, the narrower the hole diameter becomes narrower, and the erosion hole The shape of the shape approaches an inverted triangular pyramid shape. That is, the through hole has a difference in opening size between the front and back sides. This is because the difference in the opening dimension becomes more apparent as it approaches a low frequency band that is thicker than a high-frequency band quartz plate (the thickness of an AT-cut quartz plate is inversely proportional to the frequency). Therefore, in order to ensure a sufficient hole diameter for filling the through hole with a conductor and to ensure the vertical connection of the through hole, at least to one principal surface side of the crystal due to the anisotropy of the crystal An opening area having a size of 2 mm is required. That is, securing the opening area leads to a decrease in the vibration area. However, according to the structure of the present invention, the through portion 6 is formed in a partial region in the Z′-axis direction in the thin portion 28, and the wall surface conductor 7 connecting the upper end and the lower end of the through portion 6 is penetrated. It is partially attached to the inner wall surface of the part 6. That is, by passing through the wall surface conductor 7, conduction from one main surface side to the other main surface side of the vibration unit 20 can be ensured without forming a through hole. Therefore, it is possible to ensure a wide vibration region as compared with the structure in which the through hole is formed. Thereby, the design freedom of a piezoelectric vibration device can be increased.

  As a modification of the second embodiment of the present invention, the crystal diaphragm may be structured as shown in FIGS. For example, in FIG. 7, a metal brazing material is formed on the entire circumference of the first bonding electrode that covers the protrusion 8. With such a structure, the width (diameter) of the gold plating layer 50 is wider (larger diameter) than the width (diameter) of the second bonding electrode 33 of the lid member shown in FIG. It becomes easy to perform positioning and mounting at the time of temporary bonding between the first lid member 3 and the first lid member 3. Further, with such a configuration, even if a slight positional deviation occurs in the temporary bonding of the crystal diaphragm and the first lid member, the first lid member follows the crystal diaphragm side by heating and melting of the bonding material. Thus, self-correction (self-alignment effect) is easily performed.

  Further, as shown in FIG. 8, a structure in which the thin-walled portion is interrupted, that is, through the penetrating region, and the extraction electrode is routed to the first bonding electrode through the side surface of the vibrating portion without penetrating the vibrating portion. Good. In the case of such a structure, conduction from one main surface side of the vibration unit to the other main surface side can be ensured without forming a through hole by passing through the side surface of the vibration unit. Therefore, it is possible to ensure a wide vibration region as compared with the structure in which the through hole is formed. Thereby, the design freedom of a piezoelectric vibration device can be increased.

  Further, in the embodiment of the present invention, two lid members having a rectangular shape in plan view and a flat plate shape are used. However, the present invention is not limited to this, and the excitation formed on the crystal diaphragm by the two lid members. The shape of the lid member may be arbitrarily set as long as the electrode can be hermetically sealed. For example, a form in which the concave portions of the two lid members formed in a concave shape are hermetically joined so as to face the crystal diaphragm.

  In the embodiment of the present invention, a surface-mount type crystal resonator is taken as an example, but other surface-mount type used in electronic devices such as a crystal oscillator in which a crystal resonator is incorporated in an electronic component such as a crystal filter or an integrated circuit. This method can also be applied to a method for manufacturing a piezoelectric vibration device.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  It can be applied to mass production of piezoelectric vibration devices.

The cross-sectional schematic diagram of the long side direction of the crystal oscillator which shows the 1st Embodiment of this invention. The exploded sectional view of FIG. The cross-sectional schematic diagram of the long side direction of the crystal diaphragm which shows the modification of the 1st Embodiment of this invention. The top view of the crystal diaphragm which shows the 2nd Embodiment of this invention The cross-sectional schematic diagram of the long side direction of the quartz-crystal diaphragm which shows the 2nd Embodiment of this invention. The expansion perspective view of the A section of FIG. The cross-sectional schematic diagram of the long side direction of the crystal diaphragm which shows the modification of the 2nd Embodiment of this invention. The cross-sectional schematic diagram of the long side direction of the crystal diaphragm which shows the modification of the 2nd Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Crystal resonator 2 Crystal diaphragm 20 Vibrating part 23 Excitation electrode 24 Extraction electrode 25 1st joining electrode 28 Thin part 29 Frame part 3 1st cover member 33 2nd joining electrode 34 External connection terminal 4 2nd cover member 5 Bonding material 50 Gold-plated layer 51 1st bonding material 52 2nd bonding material 53 3rd bonding material 54 4th bonding material 6 penetration part 7 wall surface conductor 8 protrusion part

Claims (2)

A piezoelectric vibration device comprising a piezoelectric diaphragm having a pair of front and back excitation electrodes, and a lid member that is bonded to the front and back outer circumferences of the piezoelectric diaphragm via a bonding material and hermetically seals the excitation electrodes. ,
The piezoelectric diaphragm includes a vibrating portion on which an excitation electrode is formed;
A frame part surrounding the vibration part and formed thicker than the vibration part;
Between the vibrating part and the frame part, a thin part or a penetrating part formed thinner than the vibrating part, or a combined configuration of the thin part and the penetrating part is integrally formed,
A protrusion made of the same material as that of the vibration part is formed integrally with the vibration part on at least one main surface of the front and back main surfaces of the vibration part. A first joining electrode drawn out to the main surface side is formed;
The protruding portion is formed with a thickness such that the upper surface of the protruding portion is substantially flush with one main surface of the frame portion,
One main surface of one lid member is formed with a second bonding electrode electrically connected to an external connection terminal formed on the other main surface of the lid member,
A piezoelectric vibration device characterized in that an excitation electrode is electrically connected to an external connection terminal by integrally bonding a first bonding electrode and a second bonding electrode via a metal brazing material. When the piezoelectric diaphragm is made of an AT-cut quartz plate having a rectangular shape in plan view, the long side of the piezoelectric diaphragm is the X axis and the short side of the piezoelectric diaphragm is the Z ′ axis, the region of the thin portion Among them, a through portion is formed in a partial region in the Z′-axis direction,
A wall conductor connecting the upper end and the lower end of the penetrating part is partially attached to the inner wall surface of the penetrating part,
Excitation electrode of one main surface side of the vibrating portion, via the wall conductor routed to the other main surface, to claim 1, characterized in that connected to the first junction electrode and the electrically The piezoelectric vibration device as described.

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