JP2018117243A - Piezoelectric vibrator and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve bonding strength while maintaining compactness.SOLUTION: A piezoelectric vibrator comprises: a base member 30 having a principal surface 32a; a piezoelectric vibration element 10 mounted on the principal surface 32a; a bonding member 40, provided on the principal surface 32a, which is arranged so as to surround the piezoelectric vibration element 10 when viewed in a plane from the normal direction of the principal surface 32a; and a lid member 20 which is bonded to the base member 30 with the bonding member 40 sandwiched therebetween, and which forms, together with the base member 30, an interior space 26 for housing the piezoelectric vibration element 10. The lid member 20 has: a top surface portion 21 facing the base member 30 with the piezoelectric vibration element 10 sandwiched therebetween; and a lateral wall portion 22 connected to the top surface portion 21. The lateral wall portion 22 has: an inner surface 24 on the interior space 26 side; an outer surface 25 on a side opposite to the interior space 26; and a facing surface 23 connecting the inner surface 24 to the outer surface 25, while facing the base member 30. The bonding member 40 covers at least part of the outer surface 25, and is configured such that a height T1 on the outer surface 25 side is greater than a height T2 on the inner surface 24 side.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a piezoelectric vibrator and a manufacturing method thereof.

  For example, a crystal resonator made of an artificial crystal is widely used as a signal source of a reference signal used for an oscillation device, a band filter, or the like. In recent years, quartz resonators are required to be reduced in size, reduced in weight, and improved in durability for the purpose of use in portable communication devices that are downsized and improved in performance. In general, when the crystal resonator is downsized, the contact area of the bonding member decreases, and the bonding strength between the base member and the lid member decreases. For example, in Patent Document 1, for the purpose of stably securing bonding strength and airtightness, a base, a piezoelectric vibrating piece mounted and connected to the main surface of the base, and a piezoelectric vibrating piece having a flange are accommodated. Thus, a piezoelectric device is disclosed that includes a lid on which a flange and a base are sealed.

JP 2012-74937 A

  Since the lid member has the flange portion, a contact area between the lid member and the joining member can be secured, and the joining strength between the base member and the lid member can be improved. However, in such a configuration, when viewed from the normal direction of the main surface of the base member, the flange portion spreads outside the internal space that accommodates the crystal resonator element. There is a possibility that it will be difficult to reduce the size.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a piezoelectric vibrator capable of improving the bonding strength while maintaining a reduction in size, and a method for manufacturing the same.

  A piezoelectric vibrator according to one aspect of the present invention is provided with a base member having a main surface, a piezoelectric vibration element mounted on the main surface, and provided on the main surface, in plan view from the normal direction of the main surface. A bonding member disposed so as to surround the piezoelectric vibration element, and a lid member that is bonded to the base member with the bonding member interposed therebetween and forms an internal space that accommodates the piezoelectric vibration element together with the base member, The lid member has a top surface portion facing the base member with the piezoelectric vibration element interposed therebetween, and a side wall portion connected to the top surface portion. The side wall portion is opposite to the inner surface on the inner space side and the inner space. An outer surface on the side, an inner surface and an opposing surface that connects the outer surface and faces the base member, the joining member covers at least a part of the outer surface, and the height on the outer surface side is the height on the inner surface side. Higher than that.

  According to the above aspect, since the joining member contacts a part of the outer surface of the lid member and the opposing surface, even if the piezoelectric vibrator is downsized, the contact area between the joining member and the lid member is ensured, and the base member and The lid member can be bonded with sufficient bonding strength. Further, since the height on the outer surface side of the joining member is higher than the height on the inner surface side, the amount of gas released from the joining member to the internal space is reduced when the joining member and the lid member are joined. be able to. For this reason, even if the piezoelectric vibrator is downsized and the volume of the internal space is reduced, it is possible to suppress fluctuations in the atmospheric pressure due to the released gas and fluctuations in frequency characteristics due to the released gas adhering to the piezoelectric vibration element. it can. That is, the piezoelectric vibrator can be reduced in size.

  A method of manufacturing a piezoelectric vibrator according to another aspect of the present invention includes a step of preparing a collective base member having a plurality of base members, and a plurality of piezoelectric vibration elements to be mounted on a main surface of the collective base member. A step of providing a joining member in a region between the plurality of piezoelectric vibration elements so that the end portions close to the plurality of piezoelectric vibration elements are thin and the central portion away from the plurality of piezoelectric vibration elements is thick; Mounting the piezoelectric vibration element on the main surface of the collective base member, joining a plurality of lid members to the collective base member with the joining member so as to correspond to each of the multiple base members, A step of accommodating a plurality of piezoelectric vibration elements in a plurality of internal spaces formed by a plurality of lid members, and a collecting base along a central portion of the joining member in a region between each of the plurality of piezoelectric vibration elements. And a step of cutting the scan element and the bonding member.

  According to the above aspect, since the joining member contacts a part of the outer surface of the lid member and the opposing surface, even if the piezoelectric vibrator is downsized, the contact area between the joining member and the lid member is ensured, and the base member and The lid member can be bonded with sufficient bonding strength. Further, since the height on the outer surface side of the joining member is higher than the height on the inner surface side, the amount of gas released from the joining member to the internal space is reduced when the joining member and the lid member are joined. be able to. For this reason, even if the piezoelectric vibrator is downsized and the volume of the internal space is reduced, it is possible to suppress fluctuations in the atmospheric pressure due to the released gas and fluctuations in frequency characteristics due to the released gas adhering to the piezoelectric vibration element. it can. That is, the piezoelectric vibrator can be reduced in size.

  According to the present invention, it is possible to provide a piezoelectric vibrator capable of improving the bonding strength while maintaining a reduction in size, and a manufacturing method thereof.

FIG. 1 is an exploded perspective view showing an example of a crystal resonator. FIG. 2 is a cross-sectional view taken along the line II-II of the crystal unit shown in FIG. FIG. 3 is an enlarged view of the vicinity of the bonding member of the crystal unit shown in FIG. FIG. 4 is a diagram illustrating a process of preparing the assembly base member. FIG. 5 is a diagram illustrating a process of providing a joining member. FIG. 6 is a diagram illustrating a process of mounting the crystal resonator element. FIG. 7 is a diagram illustrating a process of joining the lid member. FIG. 8 is a diagram illustrating a process of cutting the assembly base member and the joining member and providing a cover member.

  Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar components are denoted by the same or similar reference numerals. The drawings are exemplary, the dimensions and shapes of each part are schematic, and the technical scope of the present invention should not be limited to the embodiment.

  In the following description, as an example of a piezoelectric vibrator, a quartz vibrator (Quartz Crystal Resonator Unit) including a quartz vibrator (Quartz Crystal Resonator) will be described as an example. The quartz resonator element uses a quartz piece (Quartz Crystal Blank) as a piezoelectric body that vibrates according to an applied voltage. However, the piezoelectric vibrator according to the embodiment of the present invention is not limited to the crystal vibrator, and may use another piezoelectric body such as ceramic.

<First Embodiment>
The crystal resonator according to the first embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is an exploded perspective view showing an example of a crystal resonator. FIG. 2 is a cross-sectional view taken along the line II-II of the crystal unit shown in FIG. FIG. 3 is an enlarged view of the vicinity of the bonding member of the crystal unit shown in FIG.

  As shown in FIG. 1, the crystal resonator 1 according to this embodiment includes a crystal resonator element 10, a lid member 20, a base member 30, a joining member 40, and a cover member 50. The base member 30 and the lid member 20 are holders for housing the crystal resonator element 10. In the example illustrated here, the lid member 20 has a concave shape, specifically, a box shape having an opening, and the base member 30 has a flat plate shape. The shapes of the lid member 20 and the base member 30 are not limited to the above. For example, the base member may have a concave shape.

  The crystal resonator element 10 includes a flaky crystal piece 11. The crystal piece 11 has a first main surface 12a and a second main surface 12b facing each other. The crystal piece 11 is, for example, an AT-cut type crystal piece (Quartz Crystal Blank). In the AT-cut type crystal piece, the artificial quartz crystal is referred to as a plane parallel to the plane specified by the X axis and the Z ′ axis (hereinafter referred to as “XZ ′ plane”. The same applies to the plane specified by other axes. )) Was cut out as the main surface. The X-axis, Y-axis, and Z-axis are the crystal axes of the artificial quartz, and the Y′-axis and Z′-axis are the Y-axis and Z-axis around the X-axis in the direction from the Y-axis to the Z-axis, respectively. It is an axis rotated at 35 degrees 15 minutes ± 1 minute 30 seconds. That is, in the AT-cut crystal piece 11, the first main surface 12a and the second main surface 12b correspond to the XZ ′ plane, respectively. In addition, you may apply different cuts (for example, BT cut etc.) other than AT cut for the cut angle of a crystal piece.

  The AT-cut crystal piece 11 is parallel to the long side direction in which the long side parallel to the X-axis direction extends, the short side direction in which the short side parallel to the Z′-axis direction extends, and the Y′-axis direction. A thickness direction extending in a thickness. The crystal piece 11 has a rectangular shape when viewed in plan from the normal direction of the first main surface 12a. The crystal piece 11 is located in the center and contributes to excitation, and the excitation unit 17 on the negative direction side of the X axis. And a peripheral edge portion 18 adjacent to the excitation portion 17 on the positive direction side of the X-axis. A step 13 is provided between the excitation part 17 and the peripheral part 19. The crystal piece 11 has a mesa structure in which the excitation part 17 is thicker than the peripheral parts 18 and 19. However, the shape of the crystal piece 11 is not limited to this. For example, when seen in plan view from the normal direction of the first main surface 12a, the pair of parallel arms and the arms are connected. And a comb-teeth shape having a connecting portion. Further, the crystal piece 11 may have a flat plate structure in which the thickness in the X-axis direction and the Z′-axis direction is substantially uniform, or may have an inverted mesa structure in which the excitation part 17 is thinner than the peripheral parts 18 and 19. . Further, it may be a convex shape or a beher shape in which the thickness change between the excitation portion 17 and the peripheral portions 18 and 19 changes continuously.

  A quartz resonator element using an AT-cut quartz piece has high frequency stability over a wide temperature range, is excellent in aging characteristics, and can be manufactured at low cost. In addition, the AT-cut crystal resonator element uses a thickness shear vibration mode as a main vibration.

  The crystal resonator element 10 includes a first excitation electrode 14a and a second excitation electrode 14b that constitute a pair of electrodes. The first excitation electrode 14 a is provided on the first main surface 12 a of the excitation unit 17. The second excitation electrode 14 b is provided on the second main surface 12 b of the excitation unit 17. The first excitation electrode 14a and the second excitation electrode 14b are provided to face each other with the crystal piece 11 in between. The first excitation electrode 14a and the second excitation electrode 14b are disposed so as to substantially overlap each other on the XZ ′ plane.

  The first excitation electrode 14a and the second excitation electrode 14b each have a long side parallel to the X-axis direction, a short side parallel to the Z′-axis direction, and a thickness parallel to the Y′-axis direction. . In the example shown in FIG. 1, in the XZ ′ plane, the long sides of the first excitation electrode 14a and the second excitation electrode 14b are parallel to the long side of the crystal piece 11, and the first excitation electrode 14a and the second excitation electrode 14b The short side is parallel to the short side of the crystal piece 11. The long sides of the first excitation electrode 14 a and the second excitation electrode 14 b are separated from the long side of the crystal piece 11, and the short sides of the first excitation electrode 14 a and the second excitation electrode 14 b are from the short side of the crystal piece 11. is seperated.

  The crystal resonator element 10 has a pair of extraction electrodes 15a and 15b and a pair of connection electrodes 16a and 16b. The connection electrode 16a is electrically connected to the first excitation electrode 14a via the extraction electrode 15a. The connection electrode 16b is electrically connected to the second excitation electrode 14b through the extraction electrode 15b. The connection electrodes 16 a and 16 b are terminals for electrically connecting the first excitation electrode 14 a and the second excitation electrode 14 b to the base member 30, respectively. The crystal resonator element 10 is held by the base member 30. The first main surface 12 a is located on the side opposite to the side facing the base member 30, and the second main surface 12 b is located on the side facing the base member 30.

  The extraction electrode 15a is provided on the first main surface 12a, and the extraction electrode 15b is provided on the second main surface 12b. The connection electrode 16a is provided from the first main surface 12a of the peripheral edge 18 to the second main surface 12b, and the connection electrode 16b is provided from the second main surface 12b of the peripheral edge 18 to the first main surface 12a. It has been. The first excitation electrode 14a, the extraction electrode 15a, and the connection electrode 16a are continuous, and the second excitation electrode 14b, the extraction electrode 15b, and the connection electrode 16b are continuous. In the configuration example shown in FIG. 1, the connection electrode 16a and the connection electrode 16b are arranged along the short side direction (Z′-axis direction) of the crystal piece 11, and the crystal resonator element 10 is held by one short side. This is a so-called cantilever structure. The crystal resonator element 10 may have a so-called both-end support structure that is held by both short sides. In the both-end support structure, for example, one of the connection electrode 16a and the connection electrode 16b is provided on the peripheral edge 18, and the other is the peripheral edge. Provided in the part 19.

  The material of the first excitation electrode 14a and the second excitation electrode 14b is not particularly limited. For example, the first excitation electrode 14a and the second excitation electrode 14b have a chromium (Cr) layer on the side in contact with the crystal piece 11 as a foundation layer, Also, a gold (Au) layer is provided on the side far from the crystal piece 11. By providing a metal layer that is highly reactive with oxygen on the underlayer, the adhesion between the crystal piece and the excitation electrode is improved, and by providing a metal layer that is less reactive with oxygen on the surface layer, deterioration of the excitation electrode is suppressed. Electrical reliability is improved.

  The lid member 20 has a concave shape and has a box shape opened toward the first main surface 32 a of the base member 30. The lid member 20 is joined to the base member 30, and thereby accommodates the crystal resonator element 10 in the internal space 26. The shape of the lid member 20 is not limited as long as it can accommodate the crystal resonator element 10. For example, the lid member 20 has a rectangular shape when viewed from the normal direction of the main surface of the top surface portion 21. The lid member 20 includes, for example, a long side direction in which a long side parallel to the X axis direction extends, a short side direction in which a short side parallel to the Z ′ axis direction extends, and a height parallel to the Y ′ axis direction. Direction.

  As shown in FIG. 2, the lid member 20 has an inner surface 24 and an outer surface 25. The inner surface 24 is a surface on the inner space 26 side, and the outer surface 25 is a surface opposite to the inner surface 24. The lid member 20 is connected to the top surface portion 21 facing the first main surface 32 a of the base member 30 and the outer edge of the top surface portion 21 and extends in a direction intersecting the main surface of the top surface portion 21. Part 22. The lid member 20 has a facing surface 23 that faces the first main surface 32a of the base member 30 at the concave opening end (the end of the side wall 22 on the side close to the base member 30). The facing surface 23 extends in a frame shape so as to surround the periphery of the crystal resonator element 10.

  The material of the lid member 20 is not particularly limited, but is made of a conductive material such as metal. According to this, a shield function can be added by electrically connecting the lid member 20 to the ground potential. For example, the lid member 20 is made of an alloy (for example, 42 alloy) containing iron (Fe) and nickel (Ni). Further, a gold (Au) layer for the purpose of preventing oxidation or the like may be provided on the outermost surface of the lid member 20. Alternatively, the lid member 20 may be made of an insulating material, or may be a composite structure of a conductive material and an insulating material.

  The base member 30 holds the crystal resonator element 10 so that it can be excited. The base member 30 has a flat plate shape. The base member 30 has a long side direction in which a long side parallel to the X-axis direction extends, a short side direction in which a short side parallel to the Z′-axis direction extends, and a thickness parallel to the Y′-axis direction. Extending in the thickness direction.

  The base member 30 has a base 31. The base 31 has a first main surface 32a (front surface) and a second main surface 32b (back surface) that face each other. The base 31 has an end surface 32c that connects the first main surface 32a and the second main surface 32b. The end surface 32c is a surface extending in a direction intersecting the first main surface 32a, and is formed in a frame shape along the outer edge of the first main surface 32a. The base 31 is a sintered material such as insulating ceramic (alumina). In this case, the base 31 may be laminated and sintered with a plurality of insulating ceramic sheets. Alternatively, the substrate 31 is made of an inorganic glass material (for example, silicate glass or a material mainly composed of materials other than silicate and having a glass transition phenomenon due to a temperature rise), a crystal material (for example, an AT cut crystal). Further, it may be formed of an engineering plastic having heat resistance (for example, polyimide or liquid crystal polymer) or an organic-inorganic hybrid material (for example, fiber reinforced plastic such as glass epoxy resin). The base 31 is preferably made of a heat resistant material. The substrate 31 may be a single layer or a plurality of layers. When the substrate 31 is a plurality of layers, the substrate 31 includes an insulating layer formed on the outermost layer of the first main surface 32a.

  The base member 30 includes electrode pads 33a and 33b provided on the first main surface 32a and external electrodes 35a, 35b, 35c and 35d provided on the second main surface 32b. The electrode pads 33 a and 33 b are terminals for electrically connecting the base member 30 and the crystal resonator element 10. The external electrodes 35a, 35b, 35c, and 35d are terminals for electrically connecting a circuit board (not shown) and the crystal unit 1. The electrode pad 33a is electrically connected to the external electrode 35a via a via electrode 34a extending in the Y′-axis direction, and the electrode pad 33b is an external electrode via a via electrode 34b extending in the Y′-axis direction. It is electrically connected to 35b. The via electrodes 34a and 34b are formed in via holes that penetrate the base 31 in the Y′-axis direction.

  The conductive holding members 36 a and 36 b electrically connect the pair of connection electrodes 16 a and 16 b of the crystal resonator element 10 to the pair of electrode pads 33 a and 33 b of the base member 30, respectively. Further, the conductive holding members 36 a and 36 b hold the crystal resonator element 10 on the first main surface 32 a of the base member 30 so as to be excited. The conductive holding members 36a and 36b are formed of, for example, a conductive adhesive containing a thermosetting resin, an ultraviolet curable resin, or the like, and are fillers and conductive holding members for maintaining a gap between the base member and the crystal resonator element. It contains additives such as conductive particles for imparting conductivity to the surface.

  In the configuration example shown in FIG. 1, the electrode pads 33a and 33b of the base member 30 are provided in the vicinity of the short side of the base member 30 on the X axis negative direction side on the first main surface 32a and along the short side direction. Are arranged. The electrode pad 33a is connected to the connection electrode 16a of the crystal resonator element 10 via the conductive holding member 36a, while the electrode pad 33b is connected to the connection electrode 16b of the crystal resonator element 10 via the conductive holding member 36b. Is done.

  The plurality of external electrodes 35a, 35b, 35c, and 35d are provided near the respective corners of the second main surface 32b. In the example shown in FIG. 1, the external electrodes 35a and 35b are respectively disposed directly under the electrode pads 33a and 33b. Accordingly, the external electrodes 35a and 35b can be electrically connected to the electrode pads 33a and 33b by the via electrodes 34a and 34b extending in the Y′-axis direction. In the example illustrated in FIG. 1, among the four external electrodes 35 a to 35 d, the external electrodes 35 a and 35 b disposed near the short side of the base member 30 on the X axis negative direction side receive input / output signals of the crystal resonator element 10. Input / output electrodes to be supplied. The external electrodes 35c and 35d arranged near the short side of the base member 30 on the X axis positive direction side are dummy electrodes to which input / output signals of the crystal resonator element 10 are not supplied. Such dummy electrodes are not supplied with input / output signals of other electronic elements on a circuit board (not shown) on which the crystal unit 1 is mounted. Alternatively, the external electrodes 35c and 35d may be grounding electrodes to which a ground potential is supplied. When the lid member 20 is made of a conductive material, the lid member 20 can be connected to the external electrodes 35c and 35d, which are grounding electrodes, to add an electromagnetic shielding function with high shielding performance.

  In this configuration example, the electrode pads 33a and 33b and the external electrodes 35a to 35d of the base member 30 are all made of a metal film. For example, the electrode pads 33a and 33b, the external electrodes 35a to 35d, and the sealing frame 37 are formed from a side closer to the base 31 (lower layer) to a side farther (upper layer), a molybdenum (Mo) layer, a nickel (Ni) layer, and gold ( Au) layers are stacked in this order. The via electrodes 34a and 34b can be formed by filling the via holes of the base 31 with a conductive paste made of a refractory metal such as molybdenum (Mo).

  The arrangement relationship between the electrode pads 33a and 33b and the external electrodes 35a to 35d is not limited to the above example. For example, the electrode pad 33 a may be disposed near one short side of the base member 30, and the electrode pad 33 b may be disposed near the other short side of the base member 30. In such a configuration, the crystal resonator element 10 is held by the base member 30 at both ends in the longitudinal direction of the crystal piece 11.

  Further, the arrangement of the external electrodes is not limited to the above example. For example, two input / output electrodes may be provided on the diagonal of the second main surface 32b. Alternatively, the four external electrodes may be arranged near the center of each side instead of the corner of the second main surface 32b. In addition, the number of external electrodes is not limited to four, and may be, for example, only two that are input / output electrodes. In addition, the manner of electrical connection between the connection electrode and the external electrode is not limited to the via electrode, and the electrical continuity between the connection electrode and the external electrode can be achieved by pulling out the extraction electrode on the first main surface 32a or the second main surface 32b. May be achieved. Alternatively, the base 31 of the base member 30 is formed in a plurality of layers, the via electrode extends to the intermediate layer, and the extraction electrode is drawn out in the intermediate layer, thereby electrically connecting the connection electrode and the external electrode. Also good.

  By joining both the lid member 20 and the base member 30 with the joining member 40 interposed therebetween, the crystal resonator element 10 is sealed in an internal space (cavity) 26 surrounded by the lid member 20 and the base member 30. The In this case, the atmospheric pressure in the internal space 26 is preferably in a vacuum state lower than the atmospheric pressure. According to this, the frequency characteristics of the crystal resonator 1 due to oxidation of the first excitation electrode 14a and the second excitation electrode 14b are obtained. Changes over time can be reduced.

  The joining member 40 is provided over the entire circumference of the lid member 20 and the base member 30. Specifically, the joining member 40 is provided between the facing surface 23 of the side wall portion 22 of the lid member 20 and the first main surface 32a of the base member 30, and from the normal direction of the first main surface 32a. It is arranged in a frame shape when viewed from above.

  As shown in FIG. 3, when the joining member 40 is viewed in plan from the normal direction of the first main surface 32 a, the inside of the lid member 20 (on the side of the side wall portion 22) and the lid member 20. It is also provided on the outer side (the side opposite to the inner space 26 with respect to the side wall portion 22). That is, the bonding member 40 includes a first bonding surface 42 that contacts the first main surface 32a of the base member 30, a second bonding surface 43 that contacts the opposing surface 23 of the side wall portion 22 of the lid member 20, and a second bonding. An inner peripheral surface 44 that is located closer to the inner space 26 than the surface 43 and connects the inner surface 24 and the first main surface 32a, and an outer periphery that is positioned on the opposite side of the inner space 26 and connects the outer surface 25 and the first main surface 32a. And a surface 45. In the example shown in FIG. 3, the outer peripheral surface 45 has a joining end surface 45 c that is continuous with the end surface 32 c of the base member 30. The joining end surface 45c is formed substantially flush with the end surface 32c. In addition, the outer peripheral surface 45 does not need to have the joining end surface 45c, ie, may be separated from the end surface 32c.

  The joining member 40 covers a part of the outer surface 25. The joining member 40 also covers a part of the inner surface 24. That is, the lid member 20 is in contact with the bonding member 40 on the entire opposing surface 23 and part of the outer surface 25, and is also in contact with part of the inner surface 24. The contact area of the outer surface 25 with the joining member 40 is larger than the contact area of the inner surface 24. The area of the outer peripheral surface 45 is larger than the area of the inner peripheral surface 44. The inner surface 24 may not be in contact with the bonding member 40, and a part of the facing surface 23 may not be in contact with the bonding member 40.

  Paying attention to the height parallel to the normal direction of the first main surface 32a of the base member 30 (hereinafter simply referred to as height), the height of the joining member 40 on the outer surface 25 side is T1, and the joining member 40. The height T1 is greater than the height T2 (T1> T2) where T2 is the height on the inner surface 24 side and T3 is the height of the joining member 40 in the region facing the second joining surface 43. Is larger than the height T3 (T1> T3). Further, the height T2 is larger than the height T3 (T2> T3). However, the height T2 may be equal to or smaller than the height T3 (T2 ≦ T3). The height T1 is the maximum value of the distance between the first joint surface 42 and the outer peripheral surface 45 in the normal direction of the first main surface 32a. The height T2 is the maximum value of the distance between the first joint surface 42 and the inner peripheral surface 44 in the normal direction of the first main surface 32a. The height T3 is the maximum value of the distance between the first joint surface 42 and the second joint surface 43 in the normal direction of the first main surface 32a.

  The joining member 40 is, for example, a low-melting-point glass adhesive (for example, lead boric acid type, tin phosphoric acid type, etc.) that exhibits an adhesive action by melting and solidifying by heat treatment. Since the glass adhesive emits less gas when solidified than the organic adhesive, the pressure of the internal space 26 caused by the emitted gas is increased, and the emitted gas is adsorbed by the piezoelectric vibration element 10. The fluctuation of the frequency characteristic due to this can be suppressed. After a binder and a solvent are added to the low melting point glass powder to form a paste, it is coated by a method such as printing or dispensing, and then subjected to heat treatment to remove the binder / solvent to obtain a glass adhesive layer. The low melting point glass adhesive may include lead-free vanadium glass that melts at a temperature of 300 ° C. or higher and 410 ° C. or lower. This vanadium-based glass has high reliability such as airtightness at the time of bonding, water resistance and moisture resistance. Furthermore, the thermal expansion coefficient of the vanadium glass can be flexibly controlled by controlling the glass structure. The joining member 40 is not limited to the above, and may be an organic adhesive containing a thermosetting resin or a photocurable resin. As such an adhesive, for example, an epoxy adhesive mainly composed of an epoxy resin can be used. Examples of the epoxy resin include bifunctional epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, and novolac type epoxy resins such as phenol novolac type epoxy resin and cresol novolac type epoxy resin. Moreover, what is generally known, such as a polyfunctional epoxy resin, a glycidyl amine type epoxy resin, a heterocyclic ring-containing epoxy resin, or an alicyclic epoxy resin, can also be applied. Further, the joining member 40 may be a solder member including a gold (Au) -tin (Sn) eutectic alloy and a flux. According to the metal joining using the solder member, the sealing performance can be improved.

  As shown in FIG. 3, the cover member 50 covers the outer side (outer peripheral surface 45) of the joining member 40. In other words, the cover member 50 covers at least the joining member 40 outside the lid member 20 when viewed in plan from the normal direction of the first main surface 32a of the base member 30. The cover member 50 has, for example, higher water resistance than the joining member 40 and suppresses contact of moisture with the joining member 40. The cover member 50 may be higher in airtightness than the joining member 40 and improve the sealing performance. The cover member 50 is further provided in contact with the outer surface 25 of the lid member 20 and the end surface 32 c of the base member 30. That is, the cover member 50 connects the lid member 20 and the base member 30 to improve the mechanical strength of the crystal unit 1. The cover member 50 is formed, for example, by any one of the glass adhesive, the organic adhesive, and the solder member that are given as examples of the material of the joining member 40.

In the crystal resonator element 10 according to this embodiment, one end of the crystal piece 11 in the long side direction (the end on the side where the conductive holding members 36a and 36b are disposed) is a fixed end, and the other end is a free end. It has become. In addition, the crystal resonator element 10, the lid member 20, and the base member 30 have rectangular shapes on the XZ ′ plane, and the long side direction and the short side direction are the same.

  However, the position of the fixed end of the crystal resonator element 10 is not particularly limited, and the crystal resonator element 10 may be fixed to the base member 30 at both ends of the crystal piece 11 in the long side direction. In this case, the crystal resonator element 10 and the electrodes of the base member 30 may be formed in such a manner that the crystal resonator element 10 is fixed at both ends of the crystal piece 11 in the long side direction.

  In the crystal resonator 1 according to the present embodiment, an alternating electric field is applied between the first excitation electrode 14a and the second excitation electrode 14b constituting the crystal resonator element 10 via the external electrodes 35a and 35b of the base member 30. To do. As a result, the crystal piece 11 vibrates in a predetermined vibration mode such as a thickness shear vibration mode, and resonance characteristics associated with the vibration are obtained.

Second Embodiment
Next, a method for manufacturing the crystal unit 100 according to the second embodiment of the present invention will be described with reference to FIGS. In the following description, descriptions of matters common to the above are omitted. In particular, the same operation effect by the same configuration will not be mentioned sequentially.

  FIG. 4 is a diagram illustrating a process of preparing the assembly base member. FIG. 5 is a diagram illustrating a process of providing a joining member. FIG. 6 is a diagram illustrating a process of mounting the crystal resonator element. FIG. 7 is a diagram illustrating a process of joining the lid member. FIG. 8 is a diagram illustrating a process of cutting the assembly base member and the joining member and providing a cover member.

  First, a collective base member 230 having a plurality of base members 130 is prepared (FIG. 4). In this step, a flat aggregate base 231 including a plurality of bases 131 is prepared. The aggregate base 231 is a large base before being separated into a plurality of bases 131, and is also called a mother base. In forming the aggregate base 231, a green sheet using ceramic powder whose main material is alumina is prepared. Next, a via hole is formed in a region of the green sheet corresponding to each substrate 131, and a metal paste is injected into the via hole. Next, a plurality of metal layers are provided on the first main surface 232a and the second main surface 232b facing each other of the green sheet. The metal layer is provided with a molybdenum (Mo) layer, a nickel (Ni) layer, and a gold (Au) layer in this order. The metal layer is provided by any one of physical vapor deposition (PVD), chemical vapor deposition (CVD), electroplating, and a coating process. Next, the green sheet is fired at about 1600 ° C. in a hydrogen atmosphere to obtain a ceramic aggregate substrate 231. As the aggregate base 231 is fired, the metal paste is solidified to form the via electrode 134a, and the metal layer is annealed to form the electrode pad 133a and the external electrodes 135a and 135c. Thereby, a collective (mother) base member 230 having a plurality of base members 130 is completed.

  Next, the joining member 140 is provided so as to be positioned between the mounting positions 111 of the plurality of crystal resonator elements 110 when viewed from the normal direction of the first main surface 232a of the collective base portion 30 (FIG. 5). The mounting position 111 is a region where the crystal resonator element 110 is to be mounted in a later process when viewed in plan from the normal direction of the first main surface 232a. That is, the mounting position 111 is a region located at the center of the base member 130, overlapping the electrode pad 133 a, and facing the external electrodes 135 a and 135 c with the base member 130 interposed therebetween. The joining member 140 is an unsolidified glass adhesive and is in the form of a paste. Such a joining member 140 is applied to the first main surface 232a of the assembly base member 230 by a method such as printing or dispensing so as to be away from the electrode pad 133a. Thereafter, a heat treatment is performed to remove the solvent and the binder from the paste-like glass adhesive, and the bonding agent 140 is obtained. The joining member 140 is provided in a mountain shape between the base members 130. Specifically, the joining member 140 is provided so as to be thin at an end portion close to the mounting position 111 (quartz vibration element 110) and to be thick at a central portion away from the mounting position 111 (quartz vibration element 110). In addition, the joining member 140 is provided so that the center part may overlap with the boundary of the adjacent base members 130. Therefore, in other words, the shape of the joining member 140 is formed so as to become thicker as it approaches the boundary of the base member 130 and to become thinner as it moves away from the boundary.

  Next, the plurality of crystal resonator elements 110 are mounted on the first main surface 232a of the collective base member 230 so as to face each of the plurality of base members 130 (FIG. 6). In this step, first, a conductive paste containing a thermosetting resin and conductive particles is applied on the plurality of electrode pads 133a. Next, the crystal resonator element 110 is placed on the conductive paste. At this time, the conductive paste may be heated and temporarily solidified so as to have an appropriate hardness. Next, the conductive paste is solidified by heating to maintain the state where the quartz crystal vibrating element 110 faces the first main surface 232a of the collective base member 230 and is separated from the first main surface 232a, and the conductive holding member 136a is solidified by heating. The crystal resonator element 110 is fixed and held on the base member 130 of the collective base member 230. At this time, the conductive holding member 136 a is provided so as to be separated from the bonding member 140, and the crystal resonator element 110 is mounted so as to be separated from the bonding member 140. Note that the order of the step of providing the bonding member 140 and the step of providing the crystal vibrating element 110 is not limited to the above, and the bonding member 140 may be provided after the step of providing the crystal vibrating element 110. The step of providing 140 and the step of mounting the crystal resonator element 110 may be performed simultaneously.

  Next, the joining member 140 is solidified, and the plurality of lid members 120 are joined to the aggregate base member 230 so as to correspond to each of the plurality of base members 130, and are formed by the plurality of base members 130 and the plurality of lid members 120. A plurality of piezoelectric vibration elements 110 are accommodated in a plurality of internal spaces 126 (FIG. 7). In this step, first, under a reduced pressure environment, the inner surface 124 of the top surface portion 121 faces the first main surface 232a with the quartz crystal resonator element 110 interposed therebetween, and the facing surface 123 of the side wall portion 122 faces the first main surface 232a. The lid member 120 is placed on the joining member 140 so as to face each other. That is, the crystal resonator element 110 is accommodated in the internal space 126. At this time, the end of the side wall 122 on the facing surface 123 side is buried in the paste-like bonding member 140. Next, the joining member 140 is solidified under a reduced pressure environment, and the plurality of lid members 120 are joined to the collective base member 230. That is, the internal space 126 is sealed so that the atmospheric pressure is lower than the atmospheric pressure. The joining member 140 is connected in a region not shown.

  In the cross section shown in FIG. 7, the joining member 140 belonging to different lid members 120 and having the adjacent side wall portions 122 buried therein is provided so as to continue over both the adjacent base members 130. The joining member 140 has an end portion located on the inner space 126 side of each lid member 120 and a central portion located on the outside of the lid member 120. Therefore, since the joining member 140 is provided in a mountain shape, the height of the joining member 140 on the outer surface 125 side is higher than the height on the inner surface 124 side. Specifically, the first joint surface 142 is in contact with the first main surface 232a of the collective base member 230 over both of the adjacent base members 130. Further, the first joint surfaces 142 are opposed to the two second joint surfaces 143 that are in contact with the opposed surfaces 123 of the different lid members 120. Further, the first joint surface 142 faces two inner peripheral surfaces 144 positioned inside different lid members 120, respectively. The first joint surface 142 faces the outer peripheral surface 145 located between the two adjacent side wall portions 122. Such an outer peripheral surface 145 is one continuous curved surface that connects the outer surfaces 125 of the two adjacent side wall portions 122. The distance between the first joint surface 142 and the outer peripheral surface 145 is greater than the distance between the first joint surface 142 and the inner peripheral surface 144.

  Next, the assembly base member 230 and the joining member 140 are cut along the breaking line BR shown in FIG. This cutting process is also called a dicing process or a singulation process. The break line BR extends in a direction parallel to the normal direction of the first main surface 232a of the collective base member 230. In addition, the break line BR is located between the lid members 120 when viewed in plan, and is along the central portion of the bonding member 140 in a region between each of the plurality of piezoelectric vibration elements 110. It is a straight line continuous in the base member 230. The cutting method is not particularly limited, and for example, blade dicing processing or laser dicing processing is performed.

  Next, the outer peripheral surface 145 of the joining member 140 is covered with the cover member 150 (FIG. 8). The collective base member 230 is separated into the base member 130 by the cutting process. In addition, an end surface 132c of the base member 130 and a joint end surface 145c of the joint member 140 are formed as the cut surfaces exposed by the cutting. First, an organic adhesive is applied so as to cover the outer peripheral surface 145. At this time, the adhesive is disposed so that the outer surface 125 of the lid member 120 and the end surface 132c of the base member 130 are in contact with each other. Next, the adhesive is solidified to form the cover member 150.

  As described above, according to the first embodiment, the base member 30 having the main surface 32a, the piezoelectric vibration element 10 mounted on the main surface 32a, and the main surface 32a are provided on the main surface 32a. A joining member 40 disposed so as to surround the piezoelectric vibration element 10 when seen in a plan view from the normal direction, and a base member 30 that is joined to the base member 30 with the joining member 40 interposed therebetween, and has a base in the internal space 26 that accommodates the piezoelectric vibration element 10. A lid member 20 formed with the member 30, and the lid member 20 includes a top surface portion 21 that faces the base member 30 with the piezoelectric vibration element 10 interposed therebetween, and a side wall portion 22 that is connected to the top surface portion 21. The side wall 22 has an inner surface 24 on the inner space 26 side, an outer surface 25 opposite to the inner space 26, and an opposing surface 23 that connects the inner surface 24 and the outer surface 25 and faces the base member 30. The joining member 40 has an outer surface 5 covers at least a portion, the height T1 of the side of the outer surface 25 is greater than the height T2 of the side of the inner surface 24, the piezoelectric vibrator, is provided.

  According to the first embodiment, since the joining member contacts a part of the outer surface of the lid member and the opposing surface, the contact area between the joining member and the lid member is ensured even if the piezoelectric vibrator is downsized. The base member and the lid member can be bonded with sufficient bonding strength. Further, since the height on the outer surface side of the joining member is higher than the height on the inner surface side, the amount of gas released from the joining member to the internal space is reduced when the joining member and the lid member are joined. be able to. For this reason, even if the piezoelectric vibrator is downsized and the volume of the internal space is reduced, it is possible to suppress fluctuations in the atmospheric pressure due to the released gas and fluctuations in frequency characteristics due to the released gas adhering to the piezoelectric vibration element. it can. That is, the piezoelectric vibrator can be reduced in size.

  Furthermore, a cover member 50 is provided that covers at least the joining member 40 outside the lid member 20 when viewed in plan from the normal direction of the main surface 32a of the base member 30. The cover member 50 has higher water resistance than the joining member 40. May be. According to this, the contact of moisture with the joining member can be reduced, and the reliability of the piezoelectric vibrator can be improved.

  The cover member 50 may be provided in contact with the side wall portion 22 and the base member 30. According to this, the joining of the lid member and the base member can be reinforced, and the mechanical strength of the piezoelectric vibrator can be improved.

  The base member 30 may have an end surface 32c that intersects the main surface 32a, and the joining member 40 may have a surface (joining end surface 45c) that is continuous with the end surface 32c. In other words, the joining end surface 45c is substantially flush with the end surface 32c. According to this, a plurality of lid members can be joined to a collective base member having a plurality of base members, and the base member can be singulated after forming the piezoelectric vibrator. Compared with the manufacturing method in which the base member is separated into pieces and the lid member is joined to form the piezoelectric vibrator, the manufacturing process of the piezoelectric vibrator can be simplified and the manufacturing cost can be reduced.

  As described above, according to the second embodiment, the step of preparing the collective base member 230 having the plurality of base members 130 and the plurality of piezoelectric vibration elements 110 to be mounted on the main surface 232a of the collective base member 230 are provided. A step of providing the joining member 140 in a region between them so that the end portions close to the plurality of piezoelectric vibration elements 110 are thin and the central portion away from the plurality of piezoelectric vibration elements 110 is thick; The step of mounting the plurality of piezoelectric vibration elements 110 on the main surface 232a of the collective base member 230 and the collective base with the plurality of lid members 120 sandwiching the joining member 140 so as to correspond to the respective base members 130 A plurality of inner spaces 126 formed by the plurality of base members 130 and the plurality of lid members 120 are joined to the member 230 and a plurality of inner spaces 126 are formed. The plurality of piezoelectric vibrators 100 are cut by cutting the assembly base member 230 and the joining member 140 along the central portion of the joining member 140 in the step of housing the electro-vibration element 110 and the region between each of the plurality of piezoelectric vibration elements 110. And a method of manufacturing the piezoelectric vibrator.

  According to the second embodiment, since the joining member contacts a part of the outer surface of the lid member and the opposing surface, the contact area between the joining member and the lid member is ensured even if the piezoelectric vibrator is downsized. The base member and the lid member can be bonded with sufficient bonding strength. Further, since the height on the outer surface side of the joining member is higher than the height on the inner surface side, the amount of gas released from the joining member to the internal space is reduced when the joining member and the lid member are joined. be able to. For this reason, even if the piezoelectric vibrator is downsized and the volume of the internal space is reduced, it is possible to suppress fluctuations in the atmospheric pressure due to the released gas and fluctuations in frequency characteristics due to the released gas adhering to the piezoelectric vibration element. it can. That is, the piezoelectric vibrator can be reduced in size.

  The step of forming the plurality of piezoelectric vibrators 100 includes further providing a cover member 50 that covers at least the bonding member 40 after cutting the assembly base member 230 and the bonding member 140, and the cover member 150 is formed from the bonding member 140. Also, the water resistance may be high. According to this, the contact of moisture with the joining member can be reduced, and the reliability of the piezoelectric vibrator can be improved.

  As described above, according to the present invention, it is possible to provide a piezoelectric vibrator capable of improving the bonding strength while maintaining a reduction in size, and a manufacturing method thereof.

  The embodiments described above are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed / improved without departing from the spirit thereof, and the present invention includes equivalents thereof. In other words, those obtained by appropriately modifying the design of each embodiment by those skilled in the art are also included in the scope of the present invention as long as they include the features of the present invention. For example, each element included in each embodiment and its arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be changed as appropriate. In addition, each element included in each embodiment can be combined as much as technically possible, and combinations thereof are included in the scope of the present invention as long as they include the features of the present invention.

1,100 ... Crystal resonator (piezoelectric resonator)
10, 110 ... crystal resonator element (piezoelectric resonator element)
20, 120 ... Lid member 21, 121 ... Top surface portion 22, 122 ... Side wall portion 23, 123 ... Opposing surface 24, 124 ... Inner surface 25, 125 ... Outer surface 30, 130 ... Base member 31, 131 ... Base 32a ... First main body Surface (front surface) 32b ... Second main surface (back surface) 32c, 132c ... End surface 230 ... Aggregating base member 231 ... Aggregating base member 232a ... First main surface of the aggregating base member 132b ... Second major surface of the aggregating base member 40,140 ... Joining member 42, 142 ... 1st joining surface 43, 143 ... 2nd joining surface 44, 144 ... Inner peripheral surface 45, 145 ... Outer peripheral surface 45c, 145c ... Joining end surface 50, 150 ... Cover member

Claims (6)

A base member having a main surface;
A piezoelectric vibration element mounted on the main surface;
A bonding member provided on the main surface and disposed so as to surround the piezoelectric vibration element when viewed in plan from the normal direction of the main surface;
A lid member that is joined to the base member with the joining member interposed therebetween and forms an internal space that houses the piezoelectric vibration element together with the base member,
The lid member has a top surface portion facing the base member with the piezoelectric vibration element interposed therebetween, and a side wall portion connected to the top surface portion,
The side wall includes an inner surface on the inner space side, an outer surface opposite to the inner space, and an opposing surface that connects the inner surface and the outer surface and faces the base member,
The bonding member covers at least a part of the outer surface, and the height on the outer surface side is larger than the height on the inner surface side.   Furthermore, the cover member is provided with a cover member that covers at least the joining member outside the lid member when viewed in plan from the normal direction of the main surface of the base member, and the cover member has higher water resistance than the joining member. The piezoelectric vibrator according to claim 1.   The piezoelectric vibrator according to claim 2, wherein the cover member is provided in contact with the side wall portion and the base member. The base member has an end surface that intersects the main surface;
4. The piezoelectric vibrator according to claim 1, wherein the joining member has a surface continuous with the end surface. 5. Preparing an aggregate base member having a plurality of base members;
On the main surface of the collective base member, in a region between each of the plurality of piezoelectric vibration elements to be mounted, an end portion close to the plurality of piezoelectric vibration elements is thin, and a central portion apart from the plurality of piezoelectric vibration elements is thick. A step of providing a joining member,
Mounting the plurality of piezoelectric vibration elements on the main surface of the collective base member so as to face each of the plurality of base members;
A plurality of lid members are joined to the collective base member with the joining member interposed therebetween so as to correspond to each of the plurality of base members, and a plurality of internal spaces formed by the plurality of base members and the plurality of lid members Accommodating a plurality of piezoelectric vibration elements in
Cutting the aggregate base member and the joining member along a central portion of the joining member in a region between each of the plurality of piezoelectric vibrating elements to form a plurality of piezoelectric vibrators. Child manufacturing method.   The step of forming the plurality of piezoelectric vibrators includes providing a cover member that covers at least the joining member after cutting the assembly base member and the joining member, and the cover member is more than the joining member. The method for manufacturing a piezoelectric vibrator according to claim 5, wherein the water resistance is high.