JP7462882B2 - Piezoelectric vibrator and its manufacturing method - Google Patents

Description

The present invention relates to a piezoelectric vibrator and a method for manufacturing the same.

Piezoelectric vibrators are used for a variety of purposes, such as timing devices, sensors, and oscillators, in various electronic devices such as mobile communication terminals, communication base stations, and home appliances.

As an example of a piezoelectric vibrator, Patent Document 1 discloses a quartz crystal device that includes a rectangular substrate, a frame provided along the outer periphery of the upper surface of the substrate, electrode pads provided on the upper surface of the substrate, a quartz crystal element mounted on the electrode pad, a lid for hermetically sealing the quartz crystal element, and an adhesive layer provided on the upper surface of the substrate.

JP 2018-74227 A

According to the quartz crystal device described in Patent Document 1, foreign matter can be attached to an adhesive layer provided on the upper surface of the substrate, suppressing frequency fluctuations that may occur when foreign matter directly below the quartz crystal element adheres to the quartz crystal element. However, for example, if the foreign matter attached to the quartz crystal element is scattered to an area other than the adhesive layer of the substrate or to the lid, or if the foreign matter is attached to the lid, it is difficult to capture the foreign matter, and frequency fluctuations may occur due to the attachment and detachment of the foreign matter to the quartz crystal element.

The present invention was made in consideration of these circumstances, and the object of the present invention is to provide a piezoelectric vibrator capable of suppressing frequency fluctuations and a method for manufacturing the same.

The piezoelectric vibrator according to one aspect of the present invention comprises a piezoelectric vibration element having a piezoelectric piece and an excitation electrode configured to apply a voltage to the piezoelectric piece, a base member on which the piezoelectric vibration element is mounted, a conductive holding member that electrically connects the piezoelectric vibration element and the base member, a lid member that houses the piezoelectric vibration element in an internal space provided between the base member and the lid member, and a joining member that joins the base member and the lid member, and in the internal space, at least one of the base member and the lid member is provided with a resin member that serves as a supply source of a resin film for covering foreign matter present in the internal space.

A method for manufacturing a piezoelectric vibrator according to another aspect of the present invention includes preparing a base member, preparing a lid member, providing a resin member on at least one of the base member and the lid member, mounting a piezoelectric vibration element on the base member, mounting one of the base member and the lid member on the other, and forming a resin film to cover foreign matter present in the internal space between the base member and the lid member using the resin member contained in the internal space as a supply source.

The present invention provides a piezoelectric vibrator that can suppress frequency fluctuations and a method for manufacturing the same.

1 is an exploded perspective view showing a schematic configuration of a quartz crystal resonator according to a first embodiment; 1 is a cross-sectional view illustrating a schematic configuration of a quartz crystal resonator according to a first embodiment. 1 is a plan view illustrating a schematic configuration of a base member and a quartz crystal vibrating element according to a first embodiment. 2 is a flowchart illustrating a method for manufacturing a quartz crystal resonator according to the first embodiment. FIG. 11 is a cross-sectional view illustrating a schematic configuration of a quartz crystal resonator according to a second embodiment. 13 is a plan view illustrating a schematic configuration of a base member and a quartz crystal vibrating element according to a third embodiment. FIG.

The following describes embodiments of the present invention with reference to the drawings. The drawings of each embodiment are illustrative, and the dimensions and shapes of each part are schematic, and the technical scope of the present invention should not be interpreted as being limited to the embodiment.

In order to clarify the relationship between the drawings and to help understand the positional relationship of each component, an orthogonal coordinate system consisting of the X-axis, Y'-axis, and Z'-axis may be attached to each drawing for convenience. The X-axis, Y'-axis, and Z'-axis show the orthogonal coordinate system used to specify the structure of an AT-cut quartz crystal, which is an example of a quartz crystal piece. The X-axis, Y'-axis, and Z'-axis correspond to each other in each drawing. The X-axis, Y'-axis, and Z'-axis are each related to the crystallographic axes of the quartz crystal piece 11 described below. Specifically, in an orthogonal coordinate system in which the electrical axis (polarity axis) of the quartz crystal is the X-axis, the mechanical axis of the quartz crystal is the Y-axis, and the optical axis of the quartz crystal is the Z-axis, the Y'-axis and Z'-axis correspond to the axes obtained by rotating the Y-axis and Z-axis around the X-axis by 35 degrees 15 minutes ± 1 minute 30 seconds in the direction from the Y-axis to the Z-axis.

First Embodiment
First, the configuration of a quartz crystal resonator 1 according to a first embodiment of the present invention will be described with reference to Figures 1 to 3. Figure 1 is an exploded perspective view that shows a schematic configuration of the quartz crystal resonator according to the first embodiment. Figure 2 is a cross-sectional view that shows a schematic configuration of the quartz crystal resonator according to the first embodiment. Figure 3 is a plan view that shows a schematic configuration of a base member and a quartz crystal resonator element according to the first embodiment. Note that Figure 2 is a cross-sectional view taken along line II-II of the quartz crystal resonator 1 shown in Figure 1.

The quartz crystal resonator unit 1 includes a quartz crystal resonator element 10, a base member 30, a first conductive holding member 36a and a second conductive holding member 36b constituting a pair of conductive holding members, a cover member 40, a bonding member 50, and a resin member 70. The quartz crystal resonator element 10 is housed in an internal space provided between the base member 30 and the cover member 40. That is, the base member 30 and the cover member 40 constitute a holder for housing the quartz crystal resonator element 10. In the internal space of the holder, the quartz crystal resonator element 10 is sealed in a vacuum state, for example, but may be sealed in a state filled with an inert gas such as nitrogen or a rare gas. In the example shown in FIG. 1 and FIG. 2, the base member 30 is flat, and the quartz crystal resonator element 10 is housed in a recess 49 of the cover member 40. However, as long as at least the portion of the quartz crystal vibration element 10 that is excited is housed in the holder, the shapes of the base member 30 and the lid member 40 are not limited to the above. For example, the base member 30 may have a recess on the lid member 40 side that houses at least a portion of the quartz crystal vibration element 10.

The quartz crystal element 10 is an electromechanical energy conversion element that can convert into electrical energy and mechanical energy by the piezoelectric effect. The quartz crystal element 10 includes a thin quartz crystal element 11, a first excitation electrode 14a and a second excitation electrode 14b that constitute a pair of excitation electrodes, a first extraction electrode 15a and a second extraction electrode 15b that constitute a pair of extraction electrodes, and a first connection electrode 16a and a second connection electrode 16b that constitute a pair of connection electrodes.

The crystal piece 11 has an upper surface 11A and a lower surface 11B that face each other. The upper surface 11A is located on the side opposite the side facing the base member 30, i.e., the side facing the top wall portion 41 of the cover member 40 described below. The lower surface 11B is located on the side facing the base member 30. The upper surface 11A and the lower surface 11B correspond to a pair of main surfaces of the crystal piece 11.

Quartz piece 11 is, for example, an AT-cut quartz crystal. An AT-cut quartz crystal is formed so that the main surface is a plane parallel to the plane specified by the X-axis and Z'-axis (hereinafter referred to as the "XZ' plane"; the same applies to planes specified by other axes), and the thickness is in the direction parallel to the Y'-axis. As an example, when the top surface 11A is viewed in plan, the outer edge of quartz piece 11 has a long side extending in a direction parallel to the X-axis (hereinafter referred to as the "X-axis direction"; the same applies to directions parallel to other axes) and a short side extending in the Z'-axis direction.

The quartz crystal vibration element 10 using the AT-cut quartz crystal piece 11 has high frequency stability over a wide temperature range. In the quartz crystal vibration element 10 using the AT-cut quartz crystal piece 11, the thickness shear vibration mode is used as the main vibration. The cut angle of the quartz crystal piece 11 may be a different cut other than the AT cut. For example, the BT cut, GT cut, SC cut, etc. may be applied.

When the top surface 11A of the crystal piece 11 is viewed in plan, the crystal piece 11 has an excitation section 17 where electromechanical energy conversion takes place, and a peripheral section 18 located outside the excitation section 17. The excitation section 17 is provided in the shape of a rectangular island and is surrounded by a frame-shaped peripheral section 18. The excitation section 17 has an upper surface 17A and a lower surface 17B, and the peripheral section 18 has an upper surface 18A and a lower surface 18B. The upper surfaces 17A and 18A are part of the top surface 11A of the crystal piece 11, and the lower surfaces 17B and 18B are part of the lower surface 11B of the crystal piece 11.

The crystal blank 11 has a so-called mesa structure in which the thickness of the excitation portion 17 is greater than the thickness of the peripheral portion 18. The crystal blank 11 having a mesa structure can suppress vibration leakage from the crystal vibration element 10. In addition, it can suppress frequency fluctuations caused by external stress propagating to the excitation portion 17. The crystal blank 11 has a double-sided mesa structure, and the excitation portion 17 protrudes from the peripheral portion 18 on both the upper surface 11A and the lower surface 11B. The boundary region between the excitation portion 17 and the peripheral portion 18 has a tapered shape with a continuously changing thickness. In other words, the surface connecting the upper surface 17A and the upper surface 18A of each of the excitation portion 17 and the peripheral portion 18, and the surface connecting the lower surface 17B and the lower surface 18B are inclined surfaces with a uniform inclination.

The structures of the excitation section 17 and the peripheral section 18 are not limited to the above. For example, the excitation section 17 and the peripheral section 18 may each be formed in a band shape across the entire width of the crystal blank 11 along the Z'-axis direction. The boundary region between the excitation section 17 and the peripheral section 18 may have a step shape with discontinuous thickness changes. The boundary region may have a convex structure with a continuous change in thickness, or a bevel structure with a discontinuous change in thickness. The crystal blank 11 may have a so-called inverted mesa structure in which the thickness of the excitation section 17 is smaller than the thickness of the peripheral section 18. The crystal blank 11 may be flat, with the thickness of the excitation section 17 and the thickness of the peripheral section 18 being approximately the same.

The first excitation electrode 14a and the second excitation electrode 14b are provided in the center of the excitation section 17. The first excitation electrode 14a is provided on the upper surface 17A of the excitation section 17, and the second excitation electrode 14b is provided on the lower surface 17B of the excitation section 17. The first excitation electrode 14a and the second excitation electrode 14b face each other across the excitation section 17 and are configured to be able to apply a voltage to the excitation section 17.

The first extraction electrode 15a and the second extraction electrode 15b are provided from the excitation section 17 to the peripheral section 18. The first extraction electrode 15a is connected to the first excitation electrode 14a on the upper surface 17A of the excitation section 17, and is connected to the first connection electrode 16a in the peripheral section 18. The second extraction electrode 15b is connected to the second excitation electrode 14b on the lower surface 17B of the excitation section 17, and is connected to the second connection electrode 16b in the peripheral section 18.

The first connection electrode 16a and the second connection electrode 16b are provided on the lower surface 18B of the peripheral portion 18. The first connection electrode 16a and the second connection electrode 16b are provided in a region of the peripheral portion 18 that is located on the negative side of the X-axis direction (opposite the direction of the arrow) relative to the first excitation electrode 14a and the second excitation electrode 14b. The first connection electrode 16a and the second connection electrode 16b are aligned in the Z'-axis direction, and the second connection electrode 16b is located on the negative side of the Z'-axis direction relative to the first connection electrode 16a. The first connection electrode 16a is electrically connected to the first excitation electrode 14a via the first extraction electrode 15a. The second connection electrode 16b is electrically connected to the second excitation electrode 14b via the second extraction electrode 15b.

The first excitation electrode 14a, the first extraction electrode 15a, and the first connection electrode 16a are continuous and integrally formed. The same is true for the second excitation electrode 14b, the second extraction electrode 15b, and the second connection electrode 16b. These electrodes of the quartz crystal vibration element 10 are, for example, conductive multilayer films including an underlayer made of a material that has good adhesion to the quartz crystal blank 11, and a surface layer made of a material that has good chemical stability. The underlayer is, for example, a chromium (Cr) layer, and the outermost layer is, for example, a gold (Au) layer.

The base member 30 includes a substrate 31, a first electrode pad 33a and a second electrode pad 33b that form a pair of electrode pads, a first through electrode 34a and a second through electrode 34b that form a pair of through electrodes, and a first external electrode 35a to a fourth external electrode 35d.

The base 31 is a plate-shaped insulator having an upper surface 31A and a lower surface 31B. The base 31 is, for example, a sintered material of insulating ceramic (such as alumina). From the viewpoint of suppressing thermal stress acting from the base member 30 to the quartz crystal vibrating element 10 due to thermal history such as reflow, the base 31 is preferably made of a heat-resistant material. The base 31 may be made of a material (such as quartz) having a thermal expansion coefficient close to that of the quartz crystal piece 11.

The first electrode pad 33a and the second electrode pad 33b are provided on the upper surface 31A of the base 31. The first electrode pad 33a and the second electrode pad 33b are terminals for electrically connecting the quartz crystal vibration element 10 to the base member 30. The first electrode pad 33a and the second electrode pad 33b are, for example, conductive multilayer films including an Au layer on the surface.

The first through electrode 34a and the second through electrode 34b penetrate the base 31 in the Z'-axis direction. The first through electrode 34a electrically connects the first electrode pad 33a to the first external electrode 35a. The second through electrode 34b electrically connects the second electrode pad 33b to the second external electrode 35b.

The first external electrode 35a to the fourth external electrode 35d are provided on the lower surface 31B of the base 31. The first external electrode 35a and the second external electrode 35b are terminals for electrically connecting the quartz crystal unit 1 to an external substrate. The third external electrode 35c and the fourth external electrode 35d are, for example, dummy electrodes to which electrical signals are not input or output, but may also be ground electrodes that ground the cover member 40 to improve the electromagnetic shielding function of the cover member 40.

The first conductive holding member 36a and the second conductive holding member 36b hold the quartz crystal vibration element 10 so that it can be excited. In other words, the first conductive holding member 36a and the second conductive holding member 36b hold the quartz crystal vibration element 10 so that the excitation portion 17 does not come into contact with the base member 30 and the lid member 40. The first conductive holding member 36a and the second conductive holding member 36b also electrically connect the quartz crystal vibration element 10 and the base member 30. Specifically, the first conductive holding member 36a electrically connects the first electrode pad 33a and the first connection electrode 16a, and the second conductive holding member 36b electrically connects the second electrode pad 33b and the second connection electrode 16b.

The first conductive holding member 36a and the second conductive holding member 36b are cured products of a conductive adhesive containing a thermosetting resin, a photocurable resin, or the like. The main component of the first conductive holding member 36a and the second conductive holding member 36b is, for example, a silicone resin. The first conductive holding member 36a and the second conductive holding member 36b contain conductive particles, and as the conductive particles, for example, metal particles containing silver (Ag) are used.

The main component of the first conductive holding member 36a and the second conductive holding member 36b is not limited to silicone resin as long as it is a curable resin, and may be, for example, epoxy resin or acrylic resin. Furthermore, the conductivity of the first conductive holding member 36a and the second conductive holding member 36b is not limited to being imparted by silver particles, and may be imparted by other metals, conductive ceramics, conductive organic materials, and the like. The main component of the first conductive holding member 36a and the second conductive holding member 36b may be a conductive polymer.

The lid member 40 forms an internal space between the base member 30 and the quartz crystal vibration element 10. The lid member 40 has a recess 49 that opens to the side of the base member 30, and the internal space in this embodiment corresponds to the space inside the recess 49. The lid member 40 has a flat top wall portion 41 and a side wall portion 42 that extends from the outer edge of the top wall portion 41 toward the base member 30. The recess 49 of the lid member 40 is formed by the top wall portion 41 and the side wall portion 42. The lid member 40 further has a flange portion 43 that is connected to the tip of the side wall portion 42 on the base member 30 side and extends outward along the upper surface 31A of the base body 31. When the upper surface 31A of the base body 31 is viewed in plan, the flange portion 43 extends in a frame shape so as to surround the quartz crystal vibration element 10.

The material of the lid member 40 is preferably a conductive material, and more preferably a highly airtight metal material. By making the lid member 40 out of a conductive material, the lid member 40 is endowed with an electromagnetic shielding function that reduces the amount of electromagnetic waves entering and leaving the internal space. From the perspective of suppressing the generation of thermal stress, the material of the lid member 40 is preferably a material that has a thermal expansion coefficient close to that of the base body 31, for example an Fe-Ni-Co alloy whose thermal expansion coefficient near room temperature matches that of glass or ceramics over a wide temperature range.

The bonding member 50 is provided around the entire circumference of the base member 30 and the lid member 40, and forms a rectangular frame. When the top surface 31A of the base member 30 is viewed in plan, the first electrode pad 33a and the second electrode pad 33b are disposed inside the bonding member 50, and the bonding member 50 is provided so as to surround the quartz crystal vibration element 10. The bonding member 50 bonds the base member 30 and the lid member 40, and seals the recess 49 that corresponds to the internal space. Specifically, the bonding member 50 bonds the base body 31 and the flange portion 43.

The joining member 50 is, for example, provided by a metallized layer made of molybdenum (Mo) provided on the upper surface 31A of the base 31, and a metal solder layer made of a gold-tin (Au-Sn) eutectic alloy provided between the metallized layer and the flange portion 43. The material of the joining member 50 is not limited to the above, but from the viewpoint of suppressing fluctuations in the frequency characteristics of the quartz crystal vibration element 10, it is desirable for the joining member 50 to have low moisture permeability, and it is even more desirable for the joining member 50 to have low gas permeability. In addition, in order to electrically connect the cover member 40 to the ground potential via the joining member 50, it is desirable for the joining member 50 to be conductive.

The joining member 50 is not limited to the above-mentioned metal joining. The joining member 50 may be provided by, for example, a resin-based adhesive or a glass-based adhesive. When the joining member 50 is provided by an adhesive, the joining member 50 may be provided by a conductive adhesive or an insulating adhesive. In addition, the base member 30 and the cover member 40 may be joined by seam welding.

The resin member 70 serves as a supply source of the resin film CT for covering the foreign matter DS present in the internal space. Specifically, the resin material scattered from the resin member 70 accumulates on the inner walls of the internal space, i.e., the surfaces exposed to the internal space, such as the crystal vibration element 10, base member 30, cover member 40, and joining member 50, and forms the resin film CT on the surfaces. The position of the foreign matter DS covered by the resin film CT is fixed. Therefore, even if the crystal vibrator 1 is subjected to an impact due to being dropped, or if the crystal vibration element 10 with the foreign matter DS attached thereto is excited, the foreign matter DS is prevented from adhering to the crystal vibration element 10 or falling off from the crystal vibration element 10.

The resin member may be provided on at least one of the base member 30 and the lid member 40 in the internal space, and the resin member 70 is provided on the base member 30. As shown in FIG. 3, in a plan view, the resin member 70 is provided in an area outside the quartz vibration element 10 and does not inhibit the vibration of the quartz vibration element 10. The resin member 70 is spaced apart from the bonding member 50 and is provided in an area between the quartz vibration element 10 and the bonding member 50 in a plan view. The resin member 70 is also spaced apart from the first conductive holding member 36a and the second conductive holding member 36b.

The resin member 70 is formed of a non-conductive resin material mainly composed of, for example, silicone resin, epoxy resin, acrylic resin, etc. The material of the resin member 70 is not limited to the above, as long as the resin film CT can be supplied by heating. The raw material of the resin film CT scattered from the resin member 70 is, for example, unreacted monomers and oligomers generated when the resin member 70 is provided, or low molecular weight polymers and oligomers generated by thermal decomposition of the resin member 70. In addition, when the joining member 50 is provided by resin, it is desirable that the heat resistance of the resin member 70 is lower than that of the joining member 50. In this way, the raw material of the resin film CT can be supplied from the resin member 70 without impairing the sealing property.

The resin member 70 includes four resin pieces 71, 72, 73, and 74. The resin piece 71 is located on the positive side of the X-axis relative to the crystal vibration element 10, the resin piece 72 is located on the negative side of the X-axis relative to the crystal vibration element 10, the resin piece 73 is located on the positive side of the Z'-axis relative to the crystal vibration element 10, and the resin piece 74 is located on the negative side of the Z'-axis relative to the crystal vibration element 10. That is, in a plan view, the resin pieces 71 and 72 are adjacent to the opposing short sides of the crystal vibration element 10, and the resin pieces 73 and 74 are adjacent to the opposing long sides of the crystal vibration element 10.

In order to reduce unevenness in the resin film CT, the multiple resin pieces 71 to 74 that serve as the supply source of the resin film CT are evenly arranged around the quartz crystal vibrating element 10. In other words, the intervals between adjacent resin pieces among the multiple resin pieces 71 to 74 are approximately equal in the circumferential direction surrounding the quartz crystal vibrating element 10 in a plan view. Specifically, the intervals between the resin piece 71 and the resin piece 73, the intervals between the resin piece 73 and the resin piece 72, the intervals between the resin piece 72 and the resin piece 74, and the intervals between the resin piece 74 and the resin piece 71 are approximately equal to each other. Furthermore, in order to reduce unevenness in the resin film CT, each of the resin pieces 71 and 72 is provided at the center of the quartz crystal vibrator 1 in the Z'-axis direction, and each of the resin pieces 73 and 74 is provided at the center of the quartz crystal vibrator 1 in the X-axis direction.

The number of resin pieces included in the resin member 70 is not limited to four. The number of resin pieces may be three or less, or may be five or more. However, at least one of the resin pieces is preferably provided on the opposite side of the conductive holding members 36a and 36b in the quartz crystal vibration element 10. For example, the resin member 70 may be composed of only the resin piece 71 shown in FIG. 3, or may include the resin pieces 71, 73, and 74 excluding the resin piece 72 shown in FIG. 3. In these cases, by using the first conductive holding member 36a and the second conductive holding member 36b as a supply source of the resin film CT, it is possible to reduce unevenness in the resin film CT while saving space by omitting the resin piece 72. The resin member 70 may include a resin piece arranged near the corner of the quartz crystal vibration element 10.

Next, a method for manufacturing the crystal resonator 1 according to the first embodiment will be described with reference to FIG. 4. FIG. 4 is a flow chart that shows an outline of the method for manufacturing the crystal resonator according to the first embodiment.

First, prepare the base member 30 (S10).

The base member 30 is formed, for example, by sintering ceramic powder. As an example, through holes are formed in an alumina green sheet, and the through holes are filled with an electrode material. Next, a metal film is printed (screen printing, inkjet printing, gravure printing, flexographic printing, etc.) on the green sheet, and the green sheet, electrode material, and metal film are sintered. As a result, the alumina green sheet becomes the base 31, the electrode material becomes the through electrodes 34a and 34b, and the metal film becomes the metallized layer of the bonding member 50, the electrode pads 33a and 33b, and the external electrodes 35a to 35d. The method of forming the metal film is not limited to the above printing method, and it may be formed by wet processes such as various coating methods (casting, dispensing, etc.) and various wet plating methods (electroless plating, hot-dip plating, electroplating, etc.).

The base 31 may be formed by a wafer cut from an ingot. The metal film may be formed by a dry process, such as various vapor phase growth methods such as PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). At least a portion of each of the metallized layer of the joining member 50, the electrode pads 33a, 33b, and the external electrodes 35a to 35d may be formed after sintering the green sheet.

Next, the cover member 40 is prepared (S20).

The cover member 40 is formed, for example, by pressing a metal plate. As an example, a metal plate made of an Fe-Ni-Co alloy is prepared. Next, the metal plate is pressed with a punch to deform it into a concave shape, forming the shapes of the top wall portion 41, the side wall portion 42, and the flange portion 43.

The cover member 40 may be formed by providing a recess 49 by etching a ceramic substrate, a quartz substrate, or the like.

Next, the quartz crystal vibration element 10 is mounted (S30).

First, a quartz vibration element is prepared. A quartz crystal is sliced to form a quartz wafer. The quartz wafer may be subjected to any necessary processing, such as a planarization process such as chemical mechanical polishing, or a cleaning process using a rinsing liquid. Next, a portion of the quartz wafer is removed to form the outlines of multiple quartz pieces connected to each other. Next, a portion of each of the multiple quartz pieces is removed to process each of the multiple quartz pieces into a mesa structure. The removal process is performed, for example, by etching using photolithography, but may also be performed by other processing methods such as plasma CVM (Chemical Vaporization Machining).

Next, a metal film is provided on the surface of each of the multiple crystal pieces, and a portion of the metal film is removed by etching using photolithography to form an electrode from the metal film. Note that the method of forming the electrode is not limited to etching, and the electrode may be formed by lift-off.

Finally, the quartz crystal vibration element is singulated. A thin portion that is thinner than the surrounding area is formed in the portion connecting the multiple quartz crystal pieces, and when bending stress is applied, the thin portion becomes the starting point of a crack, and the portion connecting the multiple quartz crystal pieces is broken. The thin portion is formed, for example, by using etching in the process of forming the outlines of the multiple quartz crystal pieces or in the process of processing each of the multiple quartz crystal pieces into a mesa structure. The thin portion may be formed by a scribe tool. The quartz crystal vibration element may also be singulated by cutting with a laser cutter, dicing saw, or the like.

Next, the quartz crystal vibration element 10 is bonded to the base member 30. First, a conductive adhesive paste containing a thermosetting resin is prepared. Next, the base member 30 is placed on a hot plate that has not been heated. Next, the conductive adhesive paste is applied to each of the first electrode pad 33a and the second electrode pad 33b of the base member 30. Next, the quartz crystal vibration element 10 is placed on the conductive adhesive paste so that the tip of the quartz crystal vibration element 10 does not contact the base member 30. Next, the conductive adhesive paste is heated with a hot plate to harden the conductive adhesive paste to form the first conductive holding member 36a and the second conductive holding member 36b. This bonds the first electrode pad 33a and the second electrode pad 33b of the base member 30 to the first connection electrode 16a and the second connection electrode 16b of the quartz crystal vibration element 10, respectively.

Before placing the quartz crystal vibration element 10 on the conductive adhesive paste, the conductive adhesive paste may be preheated to adjust its viscosity. The resin composition of the conductive adhesive paste is not limited to a thermosetting resin composition, and may include a light (UV) curable resin composition. In this case, step S40 may include a step of irradiating the conductive adhesive paste with light (UV).

In the process of providing the resin member 70, for example, first, a non-conductive resin-based adhesive paste containing a thermosetting resin is applied to the base member 30 before the crystal vibration element 10 is mounted. Next, the conductive adhesive paste is hardened by heating to form the resin member 70. The heat treatment for hardening the resin-based adhesive paste that becomes the resin member 70 is performed simultaneously with the heat treatment for hardening the conductive adhesive paste that becomes the first conductive holding member 36a and the second conductive holding member 36b.

The heat treatment for hardening the resin member 70 may be performed before or after the heat treatment for hardening the first conductive holding member 36a and the second conductive holding member 36b. The resin member 70 may also be provided after the crystal vibration element 10 is mounted on the base member 30. The resin member 70 may be formed from a resin-based adhesive paste that includes a photocurable resin.

Next, the quartz crystal vibration element 10 is placed inside (S40).

First, the lid member 40 is placed in the storage tray. The storage tray has a bottomed opening that can accommodate the lid member 40 with almost no gaps. The lid member is stored in the opening with the top wall upper surface 41A of the top wall portion 41 facing the bottom of the opening.

Next, metal solder is provided on the flange underside 43B of the flange portion 43. The metal solder is a gold-tin (Au-Sn) eutectic alloy. The metal solder may be provided on a metallized layer provided on the base member 30.

Next, the base member is placed in a storage tray. The base member 30 on which the quartz crystal vibration element 10 is mounted is stored in the opening with the quartz crystal vibration element 10 facing the lid member 40. At this time, the metallized layer of the base member 30 overlaps the metal solder of the lid member 40.

Next, the base member 30 and the cover member 40 are joined (S50).

The metal solder is heated to soften it, and then cooled to solidify it. The solidified metal solder forms a joining member 50 together with the metallized layer of the base member 30, joining the base member 30 and the lid member 40 together to seal the recess 49 that corresponds to the internal space. The heat treatment in step S50 corresponds to an example of the "first heat treatment" according to the present invention.

Next, the resin film CT is formed (S60).

The sealed quartz crystal resonator 1 is heated, and the raw material for the resin film CT is supplied from the resin member 70. Specifically, the raw material for the resin film CT is scattered from the resin member 70, and the raw material is deposited on the exposed surface of the internal space to form the resin film CT. The resin film CT covers the quartz crystal resonator element 10, the base member 30, the cover member 40, and the bonding member 50. The heat treatment in step S60 corresponds to an example of the "second heat treatment" according to the present invention.

In this embodiment, the first heating process and the second heating process are described as being different heating processes, but the first heating process and the second heating process may be the same heating process. In other words, the base member 30 and the lid member 40 may be bonded together and the resin film CT may be formed in a single heating process.

Finally, remove the crystal unit 1 from the storage tray.

The order of step S10 of preparing the base member 30, step S20 of preparing the lid member 40, and step of preparing the quartz vibration element 10 is not limited to the above. Step S10 may be performed after step S20, or may be performed after the step of preparing the quartz vibration element 10. Step S20 may be performed after the step of preparing the quartz vibration element 10.

The resin adhesive paste that becomes the resin member 70 may be cured after step S40 of housing the quartz crystal vibration element 10. For example, the resin adhesive paste that becomes the resin member 70 may be heated and cured using a heat treatment that cures the joining member 50 in step S50 of joining the base member 30 and the lid member 40. In such a case, the resin film CT may be formed in the curing step of the resin member 70.

As described above, in the first embodiment, the resin member 70 that serves as a supply source of the resin film CT for covering the foreign matter DS is provided on the base member 30. This suppresses the adhesion of the foreign matter DS to the quartz vibration element 10 or the falling off of the quartz vibration element 10, thereby suppressing frequency fluctuations.

The resin member 70 is provided in an area outside the quartz vibration element 10 in a plan view, so there is no deterioration in vibration characteristics due to interference between the quartz vibration element 10 and the resin member 70.

The resin member 70 is made up of multiple resin pieces 71 to 74, which are evenly arranged around the quartz crystal vibration element 10 in a plan view, reducing unevenness in the resin film CT.

In addition, at least one of the multiple resin pieces 71 to 74 is provided on the opposite side of the conductive holding members 36a, 36b in the quartz crystal vibration element 10 in a planar view. Therefore, even if the resin piece on the conductive holding members 36a, 36b side of the quartz crystal vibration element 10 in a planar view is omitted, unevenness in the resin film CT can be reduced by using the conductive holding members 36a, 36b as a supply source of the resin film CT. In other words, frequency fluctuations can be suppressed while miniaturizing the device by omitting some of the resin pieces.

The configuration of a quartz crystal resonator 1 according to another embodiment of the present invention will be described below. Note that in the following embodiment, matters common to the first embodiment will not be described, and only the differences will be described. In particular, similar effects resulting from similar configurations will not be mentioned one by one.

Second Embodiment
The configuration of the crystal resonator 2 according to the second embodiment will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view that illustrates a schematic configuration of the crystal resonator according to the second embodiment.

In this embodiment, the resin member 270 is provided on the top wall portion 41 of the lid member 40. The resin member 270 may also be provided on the side wall portion 42 of the lid member 40.

Third Embodiment
The configuration of the quartz crystal resonator 3 according to the second embodiment will be described with reference to Fig. 6. Fig. 6 is a plan view that shows a schematic configuration of a base member and a quartz crystal resonator element according to the third embodiment.

In a plan view, the resin member 370 is provided in a frame shape surrounding the quartz vibration element 10. Note that the shape of the resin member 370 is not limited to a frame shape, as long as the resin member 370 is provided along the quartz vibration element 10 or the bonding member 50 in the area surrounding the quartz vibration element 10. For example, the resin member 370 may be provided in an L shape along the corner of the quartz vibration element 10, or in a U shape on the side of the quartz vibration element 10 opposite the conductive holding members 36a and 36b.

The following describes some or all of the embodiments of the present invention. Note that the present invention is not limited to the following descriptions.

According to one aspect of the present invention, a quartz crystal oscillator is provided, which includes a quartz crystal vibration element having a piezoelectric piece and an excitation electrode configured to be able to apply a voltage to the piezoelectric piece, a base member on which the quartz crystal vibration element is mounted, a conductive holding member that electrically connects the quartz crystal vibration element and the base member, a lid member that houses the quartz crystal vibration element in an internal space provided between the base member and the lid member, and a joining member that joins the base member and the lid member, and in the internal space, at least one of the base member and the lid member is provided with a resin member that serves as a supply source of a resin film for covering foreign matter present in the internal space.

In one embodiment, the resin member is provided in an area outside the quartz crystal vibration element when viewed in a plan view.

In one embodiment, the resin member includes multiple resin pieces.

In one embodiment, the multiple resin pieces are evenly arranged around the quartz crystal vibration element in a plan view.

In one embodiment, at least one of the multiple resin pieces is provided on the opposite side of the quartz crystal vibration element from the conductive holding member when viewed in a plan view.

In one embodiment, the resin member is L-shaped, U-shaped, or frame-shaped in plan view, surrounding at least a portion of the quartz crystal vibration element.

In one embodiment, the resin member is spaced apart from the joining member.

According to another aspect of the present invention, there is provided a method for manufacturing a quartz crystal unit, the method including: preparing a base member; preparing a lid member; providing a resin member on at least one of the base member and the lid member; mounting a quartz crystal vibrating element on the base member; mounting one of the base member and the lid member on the other; and forming a resin film to cover foreign matter present in the internal space between the base member and the lid member using the resin member contained in the internal space as a supply source.

In one embodiment, the method includes a first heating process for heating the bonding material between the base member and the lid member, and a second heating process for forming a resin film using a resin material as a supply source.

In one embodiment, the first heat treatment and the second heat treatment are the same heat treatment.

In one embodiment, the first heat treatment and the second heat treatment are different heat treatments.

The embodiment of the present invention is not limited to quartz crystal resonators, but can also be applied to other piezoelectric resonators (Piezoelectric Resonator Units). Examples of piezoelectric pieces suitable for use in the piezoelectric resonator of this embodiment include piezoelectric ceramics such as lead zirconate titanate (PZT) and aluminum nitride, and piezoelectric single crystals such as lithium niobate and lithium tantalate, but the present invention is not limited to these and can be selected as appropriate.

Embodiments according to the present invention can be applied as appropriate to any device that performs electromechanical energy conversion using the piezoelectric effect, such as a timing device, a sound generator, an oscillator, or a load sensor, without any particular limitations.

As described above, one aspect of the present invention provides a piezoelectric vibrator capable of suppressing frequency fluctuations and a method for manufacturing the same.

The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit of the present invention, and equivalents are also included in the present invention. In other words, designs modified by a person skilled in the art as appropriate are also included within the scope of the present invention as long as they include the characteristics of the present invention. For example, the elements of each embodiment and their arrangement, materials, conditions, shapes, sizes, etc. are not limited to those exemplified, and can be modified as appropriate. Furthermore, the elements of each embodiment can be combined to the extent technically possible, and combinations of these are also included within the scope of the present invention as long as they include the characteristics of the present invention.

1...quartz crystal unit,
10...quartz crystal vibration element,
11... Quartz piece,
14a, 14b...excitation electrodes,
15a, 15b...extraction electrodes,
16a, 16b...connection electrodes,
17...excitation unit,
18...periphery,
30...base member,
36a, 36b...conductive holding member 40...cover member,
50: Joining member; 70: Resin member;
71, 72, 73, 74...resin pieces,
CT: resin film,
DS...foreign object.

Claims (10)

A piezoelectric vibration element having a piezoelectric piece and an excitation electrode configured to be able to apply a voltage to the piezoelectric piece;
A base member on which the piezoelectric vibration element is mounted;
a conductive holding member that electrically connects the piezoelectric vibration element and the base member;
a cover member that accommodates the piezoelectric vibration element in an internal space provided between the cover member and the base member;
a joining member that joins the base member and the lid member;
Equipped with
In the internal space, at least one of the base member and the lid member is provided with a resin member that serves as a supply source of a resin film for covering foreign matter present in the internal space ,
In a plan view, the resin member is provided in an area outside the piezoelectric vibration element,
The resin member includes a plurality of resin pieces.
Piezoelectric vibrator. In a plan view, the plurality of resin pieces are evenly arranged around the piezoelectric vibration element.
The piezoelectric vibrator according to claim 1 . In a plan view, at least one of the plurality of resin pieces is provided on an opposite side of the conductive holding member of the piezoelectric vibration element with the excitation electrode interposed therebetween .
3. The piezoelectric vibrator according to claim 1 or 2 . In a plan view, the resin member is provided in an L-shape, a U-shape, or a frame shape surrounding at least a portion of the piezoelectric vibration element.
The piezoelectric vibrator according to claim 1 . The resin member is spaced from the joining member.
The piezoelectric vibrator according to claim 1 . The piezoelectric vibration element is a quartz crystal vibration element that uses a quartz crystal piece as the piezoelectric piece.
The piezoelectric vibrator according to claim 1 . Providing a base member;
Providing a lid member;
providing a resin member on at least one of the base member and the lid member;
Mounting a piezoelectric vibration element on the base member;
mounting one of the base member and the lid member on the other;
forming a resin film to cover foreign matter present in the internal space between the base member and the lid member using the resin member contained in the internal space as a supply source;
Including,
In a plan view, the resin member is provided in an area outside the piezoelectric vibration element,
The resin member includes a plurality of resin pieces.
A method for manufacturing a piezoelectric vibrator. a first heating process for heating a joint member between the base member and the lid member;
and a second heating treatment for forming the resin film using the resin member as a supply source.
The method for manufacturing the piezoelectric vibrator according to claim 7 . The first heat treatment and the second heat treatment are the same heat treatment.
The method for manufacturing the piezoelectric vibrator according to claim 8 . The first heat treatment and the second heat treatment are different heat treatments.
The method for manufacturing the piezoelectric vibrator according to claim 8 .

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