JP7497754B2 - Piezoelectric vibrator and its manufacturing method - Google Patents

Description

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

Vibrators are used as timing devices, sensors, oscillators, etc. in various electronic devices such as mobile communication terminals, communication base stations, and home appliances. As electronic devices become more sophisticated, there is a demand for inexpensive, high-performance vibration elements.

Patent Document 1 discloses a quartz crystal oscillator in which a base member and a metallic lid member are joined via a conductive adhesive or Pb-containing low-melting point glass, and the lid member is electrically connected to the grounding electrode of the base member by this conductive adhesive, thereby suppressing noise caused by the passage of electromagnetic waves.

JP 2015-220749 A

However, when a conductive adhesive is used as a bonding material in the quartz crystal oscillator described in Patent Document 1, the viscosity of the conductive adhesive paste increases due to the addition of conductive filler, making it difficult for the conductive adhesive paste to flow and backfill leak paths. This makes it easier for leak paths to occur in areas where there is a large gap between the base member and the cover member, which can result in leak defects.

The present invention has been made in consideration of these circumstances, and the object of the present invention is to provide a piezoelectric vibrator and a manufacturing method thereof that improves reliability while suppressing noise generation.

A piezoelectric vibrator according to one aspect of the present invention comprises a piezoelectric vibration element, a base member on which the piezoelectric vibration element is mounted, and a lid member made of a conductive material that is joined to the base member with a bonding member made of a conductive material sandwiched therebetween and forms an internal space between the base member and the piezoelectric vibration element. The base member is provided with a power supply electrode to which the piezoelectric vibration element is connected and a grounding electrode used for grounding, the grounding electrode being in contact with the bonding member. The lid member has a top wall portion and a side wall portion extending from the outer edge of the top wall portion toward the base member, the side wall portion having an opposing surface that faces the base member. The lid member is provided with an insulating member that covers the opposing surface of the side wall portion along the outer edge of the top wall portion, and a metal film is provided on at least a portion of the surface of the insulating member. The metal film is provided between the insulating member and the bonding member and in contact with the side wall portion of the lid member, electrically connecting the lid member to the grounding electrode.

A method for manufacturing a piezoelectric vibrator according to one aspect of the present invention includes mounting a piezoelectric vibration element on a base member, and joining a lid member to the base member with a bonding member made of a conductive material sandwiched between the lid member and the base member to form an internal space in which the piezoelectric vibration element is disposed between the lid member and the base member, the base member being provided with a power supply electrode to which the piezoelectric vibration element is connected and a grounding electrode used for grounding, the grounding electrode being in contact with the bonding member, the lid member having a top wall portion and a side wall portion extending from an outer edge of the top wall portion toward the base member, the side wall portion having an opposing surface facing the base member, forming an insulating member covering the opposing surface of the side wall portion along the outer edge of the top wall portion of the lid member, and forming a metal film covering at least a portion of the insulating member and in contact with the side wall portion of the lid member, and joining the lid member includes joining the grounding electrode to the metal film and electrically connecting the lid member and the grounding electrode.

The present invention provides a piezoelectric vibrator and a manufacturing method thereof that suppresses noise generation while improving reliability.

1 is an exploded perspective view showing a schematic configuration of a quartz crystal resonator according to a first embodiment; 1 is a plan view illustrating 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. 2 is a plan view illustrating a schematic configuration of a base member and a crystal vibration element. FIG. 2 is a flowchart illustrating a method for manufacturing a quartz crystal resonator according to the first embodiment.

Hereinafter, an embodiment of the present invention will be described 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.

First Embodiment
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 4. 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 plan view that shows a schematic configuration of the quartz crystal resonator according to the first embodiment. Figure 3 is a cross-sectional view that shows a schematic configuration of the quartz crystal resonator according to the first embodiment. Figure 4 is a plan view that shows a schematic configuration of a base member and a quartz crystal resonator element. Note that Figure 3 is a cross-sectional view taken along line III-III of the quartz crystal resonator 1 shown in Figure 2.

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 correspond to each other in each drawing. The X-axis, Y'-axis, and Z'-axis correspond to the crystallographic axes of the quartz piece 11 described below. The X-axis corresponds to the electrical axis (polarity axis) of the quartz, the Y-axis corresponds to the mechanical axis of the quartz, and the Z-axis corresponds to the optical axis of the quartz. The Y'-axis and Z'-axis are respectively axes rotated 35 degrees 15 minutes ± 1 minute 30 seconds from the Y-axis to the Z-axis around the X-axis.

In the following description, the direction parallel to the X-axis is referred to as the "X-axis direction", the direction parallel to the Y'-axis is referred to as the "Y'-axis direction", and the direction parallel to the Z'-axis is referred to as the "Z'-axis direction". The directions of the tips of the arrows on the X-axis, Y'-axis, and Z'-axis are referred to as "+ (plus)", and the directions opposite to the arrows are referred to as "- (minus)". For convenience, the +Y'-axis direction is referred to as the upward direction, and the -Y'-axis direction is referred to as the downward direction, but the up-down orientation of the quartz crystal unit 1 is not limited. For example, in the following description, the +Y'-axis direction side of the quartz crystal unit 10 is referred to as the upper surface 11A, and the -Y'-axis direction side is referred to as the lower surface 11B, but the quartz crystal piece 11 may be arranged so that the upper surface 11A is located vertically below the lower surface 11B.

The quartz crystal vibrator 1 includes a quartz crystal vibrating element 10, a metal film 20, a base member 30, a lid member 40, a bonding member 50, and an insulating member 60. The quartz crystal vibrating element 10 is provided between the base member 30 and the lid member 40. The base member 30 and the lid member 40 form a holder for accommodating the quartz crystal vibrating element 10, and are overlapped along the Y'-axis direction. For example, the base member 30 is flat, and the lid member 40 has a bottomed opening on the base member 30 side that accommodates the quartz crystal vibrating element 10. The quartz crystal vibrating element 10 is mounted on the base member 30. Note that, as long as the quartz crystal vibrating element 10 is accommodated 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 bottomed opening on the lid member 40 side that accommodates a part of the quartz crystal vibrating element 10. The lid member 40 may also be flat. In the following description, the Y'-axis direction in which the base member 30 and the cover member 40 overlap is referred to as the "height direction."

First, the quartz crystal vibrating element 10 will be described.
The quartz crystal vibrating element 10 is an element that vibrates a quartz crystal by the piezoelectric effect and converts electrical energy into mechanical energy. The quartz crystal vibrating element 10 includes a thin quartz crystal piece 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 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 quartz piece 11 is, for example, an AT-cut quartz piece. The AT-cut quartz piece 11 is formed so that in an orthogonal coordinate system consisting of the mutually intersecting X-axis, Y'-axis, and Z'-axis, 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) is the main surface, and the direction parallel to the Y'-axis is the thickness. For example, the AT-cut quartz piece 11 is formed by etching a quartz substrate (for example, a quartz wafer) obtained by cutting and polishing a crystal of synthetic quartz crystal.

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 AT-cut quartz crystal vibration element 10, the thickness shear vibration mode is used as the main vibration. The rotation angle of the Y'-axis and Z'-axis in the AT-cut quartz crystal piece 11 may be tilted from 35 degrees 15 minutes in the range of -5 degrees to 15 degrees. The cut angle of the quartz crystal piece 11 may be a different cut other than the AT cut. For example, a BT cut, a GT cut, an SC cut, etc. may be applied. The quartz crystal vibration element may also be a tuning fork-type quartz crystal vibration element using a quartz crystal piece with a cut angle called a Z-plate.

The AT-cut crystal piece 11 is a plate-like shape with a long side extending parallel to the X-axis direction, a short side extending parallel to the Z'-axis direction, and a thickness extending parallel to the Y'-axis direction. When the top surface 11A of the crystal piece 11 is viewed in plan, the planar shape of the crystal piece 11 is rectangular.

The planar shape of the quartz blank 11 when viewed from above at the top surface 11A is not limited to a rectangular shape. The planar shape of the quartz blank 11 may be a polygonal shape, a circular shape, an elliptical shape, or a combination of these. The planar shape of the quartz blank 11 may be a tuning fork shape. In other words, the quartz blank 11 may have a base and a vibrating arm portion extending parallel to the base. Slits may be formed in the quartz blank 11 for the purpose of suppressing vibration leakage and stress propagation.

The quartz crystal piece 11 is not limited to a flat plate shape, and may have a mesa structure or an inverted mesa structure. In this case, the quartz crystal piece 11 may have a tapered shape in which the thickness changes continuously, a stepped shape in which the thickness changes discontinuously, a convex shape in which the amount of change in thickness changes continuously, or a bevel shape in which the amount of change in thickness changes discontinuously.

The first excitation electrode 14a is provided on the upper surface 11A of the crystal piece 11, and the second excitation electrode 14b is provided on the lower surface 11B of the crystal piece 11. In other words, the first excitation electrode 14a is provided on the main surface of the crystal piece 11 facing the cover member 40, and the second excitation electrode 14b is provided on the main surface of the crystal piece 11 facing the base member 30. The first excitation electrode 14a and the second excitation electrode 14b face each other across the crystal piece 11. When the upper surface 11A of the crystal piece 11 is viewed in plan, the first excitation electrode 14a and the second excitation electrode 14b are each rectangular and are arranged so that they overlap each other almost entirely.

In addition, the planar shape of the first excitation electrode 14a and the second excitation electrode 14b when the upper surface 11A of the crystal piece 11 is viewed in a planar view is not limited to a rectangular shape. The planar shape of the first excitation electrode 14a and the second excitation electrode 14b may be a polygonal shape, a circular shape, an elliptical shape, or a combination thereof.

The first extraction electrode 15a is provided on the upper surface 11A side of the crystal piece 11, and the second extraction electrode 15b is provided on the lower surface 11B side of the crystal piece 11. The first extraction electrode 15a electrically connects the first excitation electrode 14a and the first connection electrode 16a. The second extraction electrode 15b electrically connects the second excitation electrode 14b and the second connection electrode 16b. In order to reduce stray capacitance, it is desirable that the first extraction electrode 15a and the second extraction electrode 15b are separated from each other when the upper surface 11A of the crystal piece 11 is viewed in a plane. For example, the first extraction electrode 15a is provided in the +Z' axis direction when viewed from the second extraction electrode 15b.

The first connection electrode 16a and the second connection electrode 16b are electrodes for electrically connecting the first excitation electrode 14a and the second excitation electrode 14b, respectively, to the base member 30, and are provided on the lower surface 11B side of the crystal piece 11. The first connection electrode 16a is provided at the corner formed by the end of the crystal piece 11 in the -X axis direction and the end of the crystal piece 11 in the +Z' axis direction, and the second connection electrode 16b is provided at the corner formed by the end of the crystal piece 11 in the -X axis direction and the end of the crystal piece 11 in the -Z' axis direction.

One electrode group consisting of the first excitation electrode 14a, the first extraction electrode 15a, and the first connection electrode 16a is formed continuously with each other, for example, integrally with each other. The other electrode group consisting of the second excitation electrode 14b, the second extraction electrode 15b, and the second connection electrode 16b is also formed continuously with each other, for example, integrally with each other. In this way, a pair of electrode groups is provided in the quartz crystal vibration element 10. The pair of electrode groups of the quartz crystal vibration element 10 has, for example, a multi-layer structure, and is provided by stacking a base layer and a top layer in this order. The base layer is a layer that contacts the quartz crystal piece 11, and is provided with a material that has good adhesion to the quartz crystal piece 11. The top layer is a layer located on the top surface of the pair of electrode groups, and is provided with a material that has good chemical stability. This makes it possible to suppress peeling and oxidation of the pair of electrode groups, and to provide a highly reliable quartz crystal vibration element 10. The base layer contains, for example, chromium (Cr), and the top layer contains, for example, gold (Au).

The material constituting the pair of electrode groups of the quartz crystal vibration element 10 is not limited to Cr and Au, and may contain metal materials such as titanium (Ti), molybdenum (Mo), aluminum (Al), nickel (Ni), indium (In), palladium (Pd), silver (Ag), copper (Cu), tin (Sn), and iron (Fe). The pair of electrode groups may contain conductive ceramics, conductive resins, semiconductors, and the like.

Next, the base member 30 will be described.
The base member 30 holds the quartz crystal vibrating element 10 so as to be capable of vibrating. The base member 30 includes a flat substrate 31, a first electrode pad 33a and a second electrode pad 33b constituting a pair of electrode pads, an upper surface electrode 33c, a first side surface electrode 34a, a second side surface electrode 34b, a third side surface electrode 34c, and a fourth side surface electrode 34d, a first external electrode 35a, a second external electrode 35b, a third external electrode 35c, and a fourth external electrode 35d, and a protective film 39.

The base 31 has an upper surface 31A and a lower surface 31B that face each other. The upper surface 31A and the lower surface 31B correspond to a pair of main surfaces of the base 31. The upper surface 31A corresponds to the first surface of the base member 30, and the lower surface 31B corresponds to the second surface of the base member 30. The upper surface 31A is located on the side facing the quartz crystal vibration element 10 and the lid member 40, and corresponds to the mounting surface on which the quartz crystal vibration element 10 is mounted. The lower surface 31B is located on the side facing the circuit board when mounting the quartz crystal vibrator 1 on an external circuit board, and corresponds to the mounting surface to which the circuit board is connected. The base 31 is, for example, a sintered material such as insulating ceramic (alumina), but is not limited to this as long as it is an insulating material. From the viewpoint of suppressing the occurrence of thermal stress, it is preferable that the base 31 is made of a heat-resistant material. From the viewpoint of suppressing the stress applied to the quartz crystal vibration element 10 due to thermal history, the base 31 may be made of a material having a thermal expansion coefficient close to that of the quartz crystal piece 11, for example, quartz crystal. Furthermore, from the standpoint of suppressing damage to the base 31 due to thermal stress, the base 31 may be made of a material having a thermal expansion coefficient close to that of the lid member 40 .

When the upper surface 31A is viewed in plan, the base 31 has a pair of long sides that extend in the X-axis direction and face each other in the Z'-axis direction, and a pair of short sides that extend in the Z'-axis direction and face each other in the X-axis direction. Fan-shaped recesses are provided at the four corners of the base 31. These recesses are formed by dividing through holes that pass through the base 31 from the upper surface 31A to the lower surface 31B.

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. From the viewpoint of suppressing a decrease in reliability due to oxidation, it is preferable that the outermost surface of each of the first electrode pad 33a and the second electrode pad 33b contains gold, and it is more preferable that it consists almost entirely of gold. For example, the first electrode pad 33a and the second electrode pad 33b may have a laminated structure having a base layer that improves adhesion with the base 31 and an outermost surface that contains gold and suppresses oxidation.

The top electrode 33c is an electrode electrically connected to the lid member 40. The top electrode 33c is provided at the corners on the +X-axis direction side and the -Z'-axis direction side of the base member 30, and is located on the outermost surface of the base member 30 on the lid member 40 side.

The first to fourth side electrodes 34a to 34d are provided on the side of the base member 30. Specifically, they extend over the area between the upper surface 31A and the lower surface 31B of the recess provided at the corner of the base 31. In other words, the first to fourth side electrodes 34a to 34d are provided from the end of the side of the upper surface 31A to the end of the lower surface 31B, covering the recess of the base 31. Each of the first to fourth side electrodes 34a to 34d corresponds to a castellation electrode. The first side electrode 34a is provided in a recess provided at the corner of the base member 30 on the -X-axis direction side and the +Z'-axis direction side. The second side electrode 34b is provided in a recess provided at the diagonal corner of the first side electrode 43a, that is, the corner of the base member 30 on the +X-axis direction side and the -Z'-axis direction side. The third side electrode 34c is provided in a recess provided in a corner portion on the +X-axis direction side and the +Z'-axis direction side of the base member 30. The fourth side electrode 34d is provided in a recess provided at a diagonal corner of the third side electrode 34c, i.e., at the -X-axis direction side and the -Z'-axis direction side of the base member 30.

The first side electrode 34a is electrically connected to the first electrode pad 33a through a wiring electrode provided on the upper surface 31A, and the second side electrode 34b is electrically connected to the second electrode pad 33b through a wiring electrode provided on the upper surface 31A. The third side electrode 34c is provided continuously from the upper surface electrode 33c and is electrically connected to the upper surface electrode 33c. The first side electrode 34a, the first electrode pad 33a, and the wiring electrode connecting them correspond to the power supply electrode to which the quartz crystal vibration element 10 is connected. The second side electrode 34b, the second electrode pad 33b, and the wiring electrode connecting them also correspond to the power supply electrode. The third side electrode 34c and the upper surface electrode 33c correspond to the grounding electrode used to ground the cover member 40.

The first external electrode 35a to the fourth external electrode 35d are electrodes for mounting the crystal unit 1 on an external circuit board by solder or the like. The first external electrode 35a to the fourth external electrode 35d are provided on the lower surface 31B of the base body 31. The first external electrode 35a is provided at a corner on the -X axis direction side and +Z' axis direction side of the base member 30, and is electrically connected to the first side electrode 34a. The first external electrode 35a is provided at a corner on the +X axis direction side and -Z' axis direction side of the base member 30, and is electrically connected to the second side electrode 34b. The third external electrode 35c is provided at a corner on the +X axis direction side and +Z' axis direction side of the base member 30, and is electrically connected to the third side electrode 34c. The fourth external electrode 35d is provided at a corner on the -X axis direction side and -Z' axis direction side of the base member 30, and is electrically connected to the fourth side electrode 34d. The first external electrode 35a and the second external electrode 35b are used to supply an electric signal to the pair of power supply electrodes. The third external electrode 35c is used to ground the ground electrode. The fourth external electrode 35d is a dummy electrode to which electric signals are not input or output. The fourth external electrode 35d may be used together with the third external electrode 35c to ground the cover member 40, or may be omitted.

The protective film 39 is provided on the side of the base member 30 facing the lid member 40 in an area that contacts the bonding member 50. The protective film 39 covers the area facing the side wall portion 42 of the power supply electrode, and electrically insulates the power supply electrode from the lid member 40. Specifically, the protective film 39 covers the wiring electrode connecting the first side electrode 34a and the first electrode pad 33a, and covers the wiring electrode connecting the second side electrode 34b and the second electrode pad 33b. In addition, the protective film 39 reduces the unevenness of the surface of the base member 30 facing the lid member, and suppresses a decrease in sealing performance due to a local increase in thickness of the bonding member 50. The protective film 39 is provided in an area outside the upper electrode 33c, and the upper electrode 33c is exposed from the protective film 39.

The base member 30 includes a first conductive holding member 36a and a second conductive holding member 36b that constitute a pair of conductive holding members. The first conductive holding member 36a and the second conductive holding member 36b hold the quartz crystal vibration element 10 at a distance from the base member 30 and the lid member 40. The first conductive holding member 36a and the second conductive holding member 36b electrically connect the quartz crystal vibration element 10 to the base member 30. Specifically, the first conductive holding member 36a electrically connects the first electrode pad 33a to the first connection electrode 16a, and the second conductive holding member 36b electrically connects the second electrode pad 33b to 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, etc., and 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 the conductive particles are, for example, metal particles containing silver (Ag). The first conductive holding member 36a bonds the first electrode pad 33a and the first connection electrode 16a, and the second conductive holding member 36b bonds the second electrode pad 33b and the second connection electrode 16b.

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 silver particles, and may be other metals, conductive ceramics, conductive organic materials, etc. The main component of the first conductive holding member 36a and the second conductive holding member 36b may be a conductive polymer.

The resin composition of the first conductive retaining member 36a and the second conductive retaining member 36b may contain any additive. The additives may be, for example, a tackifier, a filler, a thickener, a sensitizer, an anti-aging agent, or an antifoaming agent, which are intended to improve the workability and storage stability of the conductive adhesive. In addition, a filler may be added to increase the strength of the cured product or to maintain a gap between the base member 30 and the quartz crystal vibration element 10.

Next, the cover member 40 will be described.
The cover member 40 is joined to the base member 30. The cover member 40 forms an internal space between the base member 30 and the cover member 40 to accommodate the crystal vibration element 10. The cover 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 recess 49 is liquid-tightly sealed. The material of the cover member 40 is preferably a conductive material, and more preferably a metal material with high airtightness. By making the cover member 40 out of a conductive material, an electromagnetic shielding function that reduces the ingress and egress of electromagnetic waves into the internal space is imparted to the cover member 40. From the viewpoint of suppressing the occurrence of thermal stress, the material of the cover member 40 is preferably a material having a thermal expansion coefficient close to that of the base 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 elastic modulus of the cover member 40 is preferably smaller than that of the base 31. This allows the cover member 40 to absorb impacts from the outside. Specifically, when a small external stress acts on the lid member 40, the lid member 40 undergoes elastic deformation, and when a relatively large external stress acts on the lid member 40, the lid member 40 undergoes plastic deformation. By deforming the lid member 40 in this manner, damage to the base member 30 caused by the external stress is suppressed.

The cover member 40 has a flat top wall portion 41 and a side wall portion 42 that is connected to the outer edge of the top wall portion 41 and extends along the height direction. The recess 49 of the cover member 40 is formed by the top wall portion 41 and the side wall portion 42. Specifically, the top wall portion 41 extends along the upper surface 31A of the base body 31 and faces the base member 30 in the height direction with the quartz vibration element 10 in between. The side wall portion 42 extends from the top wall portion 41 toward the base member 30 and surrounds the quartz vibration element 10 in a direction parallel to the upper surface 31A of the base body 31. The cover member 40 may further have a flange portion 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.

The lid member 40 has an inner surface located on the side of the recess 49 and an outer surface opposite the recess 49 and exposed to the outside. The inner surface is the side of the top wall portion 41 and the side wall portion 42 facing the quartz vibration element 10, and the outer surface is the side opposite the side of the top wall portion 41 and the side wall portion 42 facing the quartz vibration element 10. The lid member 40 further has an opposing surface facing the base member 30. The opposing surface is a surface that extends parallel to the upper surface 31A of the base member 30 at the tip of the side wall portion 42 of the base member 30, and can be expanded by providing a flange portion.

The planar shape of the lid member 40 when viewed in a planar view from the normal direction of the main surface is, for example, approximately rectangular. The planar shape of the lid member 40 is not limited to the above, and may be a polygonal shape, a circular shape, an elliptical shape, or a combination thereof.

Next, the insulating member 60 will be described.
The insulating member 60 is provided in a frame shape along the tip of the side wall portion 42 of the lid member 40. Specifically, it covers the opposing surface of the side wall portion 42 and covers a part of the inner surface and the outer surface. The insulating member 60 increases the contact area with the bonding member 50 to improve the bonding strength. In addition, the insulating member 60 suppresses the variation of the gap between the base member 30 and the lid member 40 due to the positional variation of the opposing surface of the side wall portion 42 caused by the undulation of the lid member 40, and suppresses the partial decrease in bonding strength and the decrease in sealing performance by making the contact surface with the bonding member 50 closer to the same plane. Since the gap between the opposing surfaces of the base member 30 and the side wall portion 42 of the lid member 40 is generally small, sufficient sealing performance can be obtained even if a conductive adhesive with reduced sealing performance due to the inclusion of a conductive filler is used as the bonding member 50. The insulating member 60 is provided between the protective film 39 and the lid member 40, between the power supply electrode and the side wall portion 42, and between the ground electrode and the side wall portion 42.

Next, the joining member 50 will be described.
The bonding member 50 is provided around the entire periphery of each of the base member 30 and the lid member 40, and forms a rectangular frame shape. When the upper 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 corresponding to the internal space. Specifically, the bonding member 50 bonds the protective film 39 and the insulating member 60, and bonds the upper surface electrode 33c and the insulating member 60. From the viewpoint of suppressing fluctuations in the frequency characteristics of the quartz crystal vibration element 10, it is desirable for the material of the bonding member 50 to have low moisture permeability, and it is even more desirable for the material to have low gas permeability.

The bonding member 50 is a conductive adhesive and electrically connects the grounding electrode and the cover member 40. The bonding member 50 is in contact with the upper electrode 33c and the metal film 20. From the viewpoint of suppressing a short circuit between the quartz crystal vibration element 10 and the cover member 40, the bonding member 50 may be an anisotropic conductive adhesive. That is, the bonding member 50 may have conductivity along the Y'-axis direction and insulation along the XZ' plane. The bonding member 50 is, for example, a resin-based adhesive containing a thermosetting resin such as an epoxy-based resin. The bonding member 50 may be a resin-based adhesive containing an epoxy-based, vinyl-based, acrylic-based, urethane-based, imide-based, or silicone-based thermosetting resin or photocurable resin.

Next, the metal film 20 will be described.
The metal film 20 is provided between the insulating member 60 and the bonding member 50 and in contact with the side wall portion 42 of the lid member 40, electrically connecting the lid member 40 and the ground electrode. In a plan view of the lid member 40, the metal film 20 is provided outside the area overlapping with the power supply electrode and in the area overlapping with the ground electrode. In a plan view of the lid member 40, the metal film 20 covers the insulating member 60 provided at the corner of the lid member 40 so as to overlap with the upper surface electrode 33c. In addition, the metal film 20 is provided outside the area overlapping with the crystal vibration element 10. The metal film 20 is in contact with each part of the inner surface and the outer surface of the side wall portion 42. The metal film 20 has a laminated structure of, for example, Cr and Au. The thickness of the metal film 20 is, for example, about 0.5 to 10 μm.

Next, a method for manufacturing the quartz crystal oscillator 1 will be described with reference to Figure 5. Figure 5 is a flow chart that shows an outline of the method for manufacturing the quartz crystal oscillator according to the first embodiment.

First, a metal plate is processed into a concave shape (S11).
A metal plate made of an Fe-Ni-Co alloy is prepared, and the top wall and side wall of the lid member are formed by drawing the metal plate, which is deformed by a press method.

Next, an insulating member is formed on the tip of the side wall portion (S13).
A resin-based adhesive is applied to the sidewalls and dried. At this time, the amount of resin-based adhesive applied is changed according to the height from the connection part with the top wall to the tip. A larger amount of resin-based adhesive is applied to the tip of a sidewall with a smaller height than to the tip of a sidewall with a larger height, so that the contact surface with the joining member provided by the insulating member approaches the same plane.

Next, a metal film is formed (S15).
The metal film is provided on the insulating member and the lid member by, for example, a sputtering method or a vacuum deposition method. First, a Cr film having good electrical connectivity with the lid member is formed, and then a Au film having good chemical stability is formed. The method of forming the metal film is not limited to the above, and can be suitably selected from dry processes such as PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). In addition, the metal film may be formed by wet processes such as various printing methods (screen printing, inkjet printing, gravure printing, flexographic printing, etc.), various coating methods (casting, dispensing, etc.), and various wet plating methods (electroless plating, hot-dip plating, electroplating, etc.).

Next, electrodes are provided on the substrate (S21).
A metal film is patterned on an alumina green sheet, and the metal film is sintered together with the green sheet. In this way, a base is formed from the green sheet, and a power supply electrode, a ground electrode, and an external electrode are formed from the metal film. The base may be formed by a wafer cut from an ingot. At least a part of the electrodes of the base member may be formed after sintering the green sheet.

Next, a portion of the electrode is covered with a protective film (S23).
The protective film is formed of, for example, a solder resist. The protective film may be formed of a suitable thermosetting resin or photosetting resin.

Next, a quartz crystal vibrating element is mounted (S25).
A conductive adhesive paste containing a thermosetting resin composition is applied onto the electrode pads of the base member. Next, the crystal vibration element 10 is placed on the conductive adhesive paste, and the conductive adhesive paste is heated and cured.

Next, the base member and the cover member are joined together (S31).
The cover member is placed in a tray so that the inner surface is exposed, and an adhesive paste containing a thermosetting resin composition is applied to the tip of the side wall of the cover member. Next, the base member is placed in the tray and placed on the cover member. Next, the adhesive paste is heated and hardened to seal the internal space containing the crystal vibration element.

The order of steps S11 to S15 from forming the lid member to forming the metal film, and steps S21 to S25 from preparing the base member to mounting the quartz crystal vibration element, is not limited to the above. Steps S11 to S15 may be performed after steps S21 to S25.

As described above, in this embodiment, the quartz crystal vibrator 1 comprises an insulating member 60 that covers the opposing surface of the side wall portion 42 of the cover member 40, a metal film 20 that covers a portion of the insulating member 60 and contacts the side wall portion 42 of the cover member 40, and a joining member 50 that seals the internal space that accommodates the quartz crystal vibrating element 10 and electrically connects the cover member 40 to the grounding electrode.
According to this, the insulating member 60 suppresses the variation in the gap between the base member 30 and the lid member 40 due to the variation in the position of the opposing surface of the side wall portion 42 caused by the undulation of the lid member 40, and by bringing the contact surface with the bonding member 50 closer to the same plane, it is possible to suppress a partial decrease in bonding strength and a decrease in sealing performance. Furthermore, since the gap between the opposing surfaces of the base member 30 and the side wall portion 42 of the lid member 40 is reduced overall, sufficient sealing performance can be obtained even if a conductive adhesive with reduced sealing performance due to the inclusion of a conductive filler is used as the bonding member 50. Furthermore, since the insulating member 60 increases the contact area with the bonding member 50, the bonding strength is improved.

In a plan view of the cover member 40, the metal film 20 is provided outside the area overlapping with the power supply electrode and in the area overlapping with the ground electrode.
Since the lid member 40 is a conductive material, the entire lid member 40 can be grounded by contacting a part of the lid member 40 with the metal film 20. Therefore, by limiting the areas of the lid member 40 and the insulating member 60 that are covered with the metal film 20, the amount of metal film 20 used can be reduced.

The bonding member 50 is an anisotropic conductive adhesive.
The bonding member 50, which is an anisotropic conductive adhesive, is conductive in a direction intersecting the main surface of the base member 30, and is insulating in a direction parallel to the main surface of the base member 30. This can suppress a short circuit between the quartz crystal vibrating element 10 and the cover member 40 even if the protective film 39 is defective and the bonding member 50 comes into contact with the power supply electrode, or if the adhesive paste of the bonding member 50 before hardening spreads and the bonding member 50 comes into contact with the power supply electrode.

The base member 30 is provided with a protective film 39 made of an insulating material that covers the area facing the side wall portion 42 of the power supply electrode.
This can prevent a short circuit between the quartz crystal vibrating element 10 and the lid member 40. In addition, the protective film 39 reduces the irregularities on the surface of the base member 30 facing the lid member, and prevents a decrease in sealing performance due to a local increase in thickness of the bonding member 50.

Below, some or all of the embodiments of the present invention are described, along with their effects. Note that the present invention is not limited to the following notes.

According to one aspect of the present invention, there is provided a quartz crystal resonator comprising: a quartz crystal element; a base member on which the quartz crystal element is mounted; and a lid member made of a conductive material that is joined to the base member with a bonding member made of a conductive material sandwiched therebetween and that forms an internal space between the base member and the quartz crystal element, wherein the base member is provided with a power supply electrode to which the quartz crystal element is connected and a grounding electrode used for grounding, the grounding electrode being in contact with the bonding member, the lid member having a top wall portion and a side wall portion extending from an outer edge of the top wall portion toward the base member, the side wall portion having an opposing surface that faces the base member, the lid member is provided with an insulating member that covers the opposing surface of the side wall portion along the outer edge of the top wall portion, and a metal film is provided on at least a portion of a surface of the insulating member, the metal film being provided between the insulating member and the bonding member and in contact with the side wall portion of the lid member, electrically connecting the lid member to the grounding electrode.
According to this, the insulating member suppresses the variation of the gap between the base member and the lid member due to the variation of the position of the opposing surface of the side wall portion caused by the undulation of the lid member, and by bringing the contact surface with the bonding member closer to the same plane, it is possible to suppress a partial decrease in bonding strength and a decrease in sealing performance. Furthermore, since the gap between the opposing surfaces of the side wall portion of the base member and the lid member is generally small, sufficient sealing performance can be obtained even if a conductive adhesive with reduced sealing performance due to the inclusion of a conductive filler is used as the bonding member. Furthermore, since the insulating member increases the contact area with the bonding member, the bonding strength is improved.

In one aspect, in a plan view of the lid member, the metal film is provided outside a region overlapping with the power supply electrode and in a region overlapping with the ground electrode.
Since the lid member is made of a conductive material, the entire lid member can be grounded by contacting only a part of the lid member with the metal film. Therefore, by limiting the areas of the lid member and the insulating member that are covered with the metal film, the amount of metal film used can be reduced.

In one embodiment, the bonding material is an anisotropic conductive adhesive.
The bonding member, which is an anisotropic conductive adhesive, is conductive in a direction intersecting the main surface of the base member and is insulating in a direction parallel to the main surface of the base member, for example. This makes it possible to suppress a short circuit between the quartz crystal resonator element and the cover member even if a defect in the protective film causes the bonding member to come into contact with the power supply electrode, or if the adhesive paste of the bonding member before hardening spreads and causes the bonding member to come into contact with the power supply electrode.

In one embodiment, the base member is provided with a protective film made of an insulating material that covers an area facing the side wall portion of the power supply electrode.
This makes it possible to prevent a short circuit between the quartz crystal vibrating element and the lid member. Also, the protective film reduces the irregularities on the surface of the base member facing the lid member, thereby preventing a decrease in sealing performance due to a local increase in thickness of the bonding member.

In one embodiment, the metal film contacts a portion of each of the inner and outer surfaces of the side wall portion.

According to another aspect of the present invention, a method for manufacturing a quartz crystal resonator can be provided, the method including: mounting a quartz crystal resonator element on a base member; joining a lid member to the base member with a bonding member made of a conductive material sandwiched between the lid member and the base member to form an internal space in which the quartz crystal resonator element is disposed between the lid member and the base member; the base member is provided with a power supply electrode to which the piezoelectric resonator element is connected and a grounding electrode used for grounding, the grounding electrode being in contact with the bonding member; the lid member having a top wall portion and a side wall portion extending from an outer edge of the top wall portion toward the base member, the side wall portion having an opposing surface facing the base member; forming an insulating member covering the opposing surface of the side wall portion along the outer edge of the top wall portion of the lid member; and forming a metal film covering at least a portion of the insulating member and in contact with the side wall portion of the lid member; and joining the lid member includes joining the grounding electrode and the metal film to electrically connect the lid member and the grounding electrode.
In one embodiment, forming the metal film includes forming the metal film by a sputtering method or a vacuum deposition method.

The embodiment according to the present invention is not limited to a quartz resonator, but can also be applied to a piezoelectric resonator. An example of a piezoelectric resonator (Piezoelectric Resonator Unit) is a quartz resonator (Quartz Crystal Resonator Unit) equipped with a quartz crystal resonator element (Quartz Crystal Resonator). The quartz crystal resonator element uses a quartz crystal element (Quartz Crystal Element) as a piezoelectric piece excited by the piezoelectric effect, but the piezoelectric piece may be formed of any piezoelectric material such as a piezoelectric single crystal, a piezoelectric ceramic, a piezoelectric thin film, or a piezoelectric polymer film. As an example, the piezoelectric single crystal can be lithium niobate (LiNbO ₃ ). Similarly, examples of the piezoelectric ceramic include barium titanate (BaTiO ₃ ), lead titanate (PbTiO ₃ ), lead zirconate titanate (Pb(Zr _x Ti _1-x )O3; PZT), aluminum nitride (AlN), lithium niobate (LiNbO ₃ ), lithium metaniobate (LiNb ₂ O ₆ ), bismuth titanate (Bi ₄ Ti ₃ O ₁₂ ), lithium tantalate (LiTaO ₃ ), lithium tetraborate (Li ₂ B ₄ O ₇ ), langasite (La ₃ Ga ₅ SiO ₁₄ ), and tantalum pentoxide (Ta ₂ O ₅ ). Examples of the piezoelectric thin film include a film formed by depositing the above-mentioned piezoelectric ceramic on a substrate such as quartz or sapphire by a sputtering method or the like. Examples of the piezoelectric polymer film include polylactic acid (PLA), polyvinylidene fluoride (PVDF), or vinylidene fluoride/trifluoroethylene (VDF/TrFE) copolymer. The above-mentioned various piezoelectric materials may be used by laminating them together, or may be laminated on other members.

Embodiments of the present invention can be applied as appropriate to any device that performs electromechanical energy conversion through 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 and a manufacturing method thereof that suppresses noise generation while improving reliability.

Note that 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/improved without departing from the spirit of the present invention, and equivalents are also included in the present invention. In other words, any design modifications made by a person skilled in the art to each embodiment 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. For example, the vibration element and vibrator of the present invention can be used in a timing device or load sensor. In addition, the elements of each embodiment can be combined to the extent technically possible, and any combination of these is included within the scope of the present invention as long as it includes the characteristics of the present invention.

1...quartz crystal unit,
10...quartz crystal vibration element,
20...metal film,
30...base member,
31...base,
33a, 33b...electrode pads,
34a to 34d: side electrodes,
35a to 35d: external electrodes,
40...Cover member,
41...Ceiling wall portion,
42...side wall portion,
50...Joining member,
60...insulating member,

Claims (5)

A piezoelectric vibration element;
A base member on which the piezoelectric vibration element is mounted;
a conductive cover member that is bonded to the base member via a conductive bonding member and that forms an internal space between the base member and the cover member and in which the piezoelectric vibration element is disposed;
Equipped with
the base member is provided with a power supply electrode to which the piezoelectric vibration element is connected and a ground electrode used for grounding, the ground electrode being in contact with the joining member;
the cover member has a top wall portion and a side wall portion extending from an outer edge of the top wall portion toward the base member, the side wall portion having an opposing surface opposing the base member,
The cover member is provided with an insulating member that covers the opposing surface of the side wall portion along an outer edge of the top wall portion,
a metal film is provided on at least a portion of a surface of the insulating member;
the metal film is provided between the insulating member and the bonding member and in contact with the side wall portion of the lid member, electrically connecting the lid member and the ground electrode;
The bonding material is an anisotropic conductive adhesive . In a plan view of the cover member, the metal film is provided outside a region overlapping with the power supply electrode and in a region overlapping with the ground electrode.
The piezoelectric vibrator according to claim 1 . a protective film made of an insulating material is provided on the base member to cover an area facing the side wall portion of the power supply electrode;
3. The piezoelectric vibrator according to claim 1 or 2 . The metal film is in contact with a part of each of the inner surface and the outer surface of the side wall portion.
The piezoelectric vibrator according to claim 1 . Mounting the piezoelectric vibration element on a base member;
a conductive bonding member is sandwiched between the cover member and the base member to form an internal space between the cover member and the base member in which the piezoelectric vibration element is disposed;
Including,
the base member is provided with a power supply electrode to which the piezoelectric vibration element is connected and a ground electrode used for grounding, the ground electrode being in contact with the joining member;
The cover member has a top wall portion and a side wall portion extending from an outer edge of the top wall portion toward the base member, the side wall portion having an opposing surface opposing the base member,
forming an insulating member covering the opposing surface of the side wall portion along an outer edge of the top wall portion of the lid member;
forming a metal film covering at least a portion of the insulating member and in contact with the side wall portion of the lid member;
Further comprising:
joining the lid member includes joining the ground electrode and the metal film to electrically connect the lid member and the ground electrode;
The method for manufacturing a piezoelectric vibrator , wherein forming the metal film includes forming the metal film by a sputtering method or a vacuum deposition method .

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