JP7465458B2 - Piezoelectric transducer - Google Patents

Description

The present invention relates to a piezoelectric vibrator.

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, 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, in the quartz crystal unit described in Patent Document 1, if the conductive filler is too small, the cover member may not be able to be grounded due to poor contact between the conductive filler and the cover member. Also, if the conductive filler is too large, the increased thickness of the conductive adhesive may reduce sealing performance.

The present invention has been made in consideration of these circumstances, and the object of the present invention is to provide a piezoelectric vibrator that can suppress noise while reducing the occurrence of defective products.

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 of a conductive material that is bonded to the base member with a bonding member of conductive adhesive sandwiched therebetween and forms an internal space between the base member and the piezoelectric vibration element, the lid member having 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 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 electrically connected to the lid member via the bonding member, the conductive adhesive comprising a resin-based adhesive and a conductive filler dispersed in the resin-based adhesive, and the particle size R of the conductive filler satisfies the relationship 4 μm≦R≦15 μm.

A piezoelectric vibrator according to one aspect of the present invention includes a piezoelectric vibration element, a base member on which the piezoelectric vibration element is mounted, and a lid member of a conductive material that is bonded to the base member with a bonding member of conductive adhesive sandwiched therebetween and forms an internal space between the base member and the piezoelectric vibration element. 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 has an opposing surface that faces the base member. 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 is electrically connected to the lid member via the bonding member. The conductive adhesive includes a resin-based adhesive and a conductive filler dispersed in the resin-based adhesive. The base member is provided with a protective film of an insulating material that covers at least the area of the power supply electrode that faces the opposing surface. The protective film is in contact with the bonding member. A gap G1 between the grounding electrode and the opposing surface and a gap G2 between the protective film and the opposing surface satisfy the relationship 0≦G2-G1≦13 μm.

The present invention provides a piezoelectric vibrator that can suppress noise while reducing the occurrence of defective products.

1 is an exploded perspective view showing a schematic configuration of a quartz crystal resonator according to an embodiment; 1 is a plan view illustrating a schematic configuration of a crystal resonator according to an embodiment. 1 is a cross-sectional view illustrating a schematic configuration of a quartz crystal resonator according to an embodiment. 2 is a plan view illustrating a schematic configuration of a base member and a crystal vibration element. FIG. FIG. 2 is an enlarged cross-sectional view of a quartz crystal resonator including a ground electrode. FIG. 2 is an enlarged cross-sectional view of a quartz crystal resonator including a power supply electrode. 1 is a table showing the ground failure rate and the leakage failure rate when the particle size R is changed. 13 is a table showing the leakage defect rate when the gap G1 and the gap G2 are changed.

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.

The configuration of a quartz crystal resonator 1 according to an 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 a quartz crystal resonator according to an embodiment. Figure 2 is a plan view that shows a schematic configuration of a quartz crystal resonator according to an embodiment. Figure 3 is a cross-sectional view that shows a schematic configuration of a quartz crystal resonator according to an 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 conveniently attached to each drawing. The X-axis, Y'-axis, and Z'-axis correspond to each other in each drawing. The X-axis, Y'-axis, and Z'-axis each relate to the crystallographic axes of the quartz piece 11 described below. The X-axis corresponds to the electrical axis (polarity axis) of the quartz crystal, the Y-axis corresponds to the mechanical axis of the quartz crystal, and the Z-axis corresponds to the optical axis of the quartz crystal. The Y'-axis and Z'-axis are respectively axes rotated 35 degrees 15 minutes ± 1 minute 30 seconds around the X-axis from the Y-axis to the Z-axis.

In the following explanation, 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". Additionally, 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 the arrows are referred to as "- (minus)". For convenience, the +Y'-axis direction will be described as the upward direction and the -Y'-axis direction as the downward direction, but the up and down orientation of the quartz crystal unit 1 is not limited to this.

The quartz crystal vibrator 1 comprises a quartz crystal vibrating element 10, a base member 30, a lid member 40, and a bonding member 50. 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 housing the quartz crystal vibrating element 10, and are overlapped along the Y'-axis direction. The quartz crystal vibrating element 10 is mounted on the base member 30.

First, the quartz crystal vibrating element 10 will be described.
The quartz crystal vibration element 10 is a piezoelectric vibration element that vibrates a quartz crystal by the piezoelectric effect and converts electrical energy into mechanical energy. The quartz crystal vibration 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 crystal piece 11 is, for example, an AT-cut quartz crystal. The AT-cut quartz crystal piece 11 is formed such 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 the other axes) is the main surface, and the direction parallel to the Y'-axis is the thickness.

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 quartz crystal piece 11 may be cut in a different way other than the AT cut. For example, the BT cut, GT cut, 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-cut.

As an example, the quartz piece 11 is flat 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 quartz piece 11 is viewed in plan, the planar shape of the quartz piece 11 is rectangular.

The crystal blank 11 is not limited to a flat plate shape, and may have a mesa structure or an inverted mesa structure. In this case, the crystal blank 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. 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 each have a rectangular shape and are arranged so that they overlap each other almost entirely.

The first extraction electrode 15a is provided on the upper surface 11A of the crystal piece 11, and the second extraction electrode 15b is provided on the lower surface 11B 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.

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 of the quartz crystal piece 11.

The excitation electrode, the extraction electrode, and the connection electrode are, for example, laminates consisting of a base layer having good adhesion to the crystal blank 11 and a top layer having good chemical stability. The materials constituting the excitation electrode, the extraction electrode, and the connection electrode are suitably selected from metal materials such as chromium (Cr), gold (Au), titanium (Ti), molybdenum (Mo), aluminum (Al), nickel (Ni), indium (In), palladium (Pd), silver (Ag), copper (Cu), tin (Sn), and iron (Fe). The excitation electrode, the extraction electrode, and the connection electrode may contain conductive ceramics, conductive resins, semiconductors, etc.

Next, the base member 30 will be described.
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, a top electrode 33c, a first side electrode 34a, a second side electrode 34b, a third side electrode 34c, a fourth side electrode 34d, a first external electrode 35a, a second external electrode 35b, a third external electrode 35c, 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 is located on the side facing the quartz crystal resonator element 10 and the lid member 40, and the lower surface 31B is located on the side facing the circuit board, for example, when the quartz crystal resonator 1 is mounted on the external circuit board. The base 31 is a sintered material such as insulating ceramic (alumina), but may also be made of quartz crystal, silicon, etc.

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 vibration element 10 to the base member 30. When the upper surface 31A of the base 31 is viewed in a plan view, the first electrode pad 33a and the second electrode pad 33b are surrounded by the bonding member 50.

The top electrode 33c is an electrode that is 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 side electrode 34a to the fourth side electrode 34d are provided on the side surface connecting the outermost edge of the upper surface 31A and the outermost edge of the lower surface 31B of the base member 30. Specifically, they are provided from the end of the upper surface 31A side of the recess provided at the corner of the base 31 to the end of the lower surface 31B side, covering the recess of the base 31. Each of the first side electrode 34a to the fourth side electrode 34d corresponds to a castellation electrode. The first side electrode 34a is provided in a recess provided at a corner of the base member 30 on the -X axis side and the +Z' axis side. The second side electrode 34b is provided in a recess provided at a corner of the base member 30 on the +X axis side and the -Z' axis side. The third side electrode 34c is provided in a recess provided at a corner of the base member 30 on the +X axis side and the +Z' axis side. The fourth side electrode 34d is provided in a recess provided at a corner of the base member 30 on the -X axis side and the -Z' axis side.

The first side electrode 34a is electrically connected to the first electrode pad 33a via the wiring electrode 37a provided on the upper surface 31A, and the second side electrode 34b is electrically connected to the second electrode pad 33b via the wiring electrode 37b 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 37a 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 37b 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 power supply electrode and the ground electrode are, for example, laminates consisting of a base layer having good adhesion to the substrate 31 and a top layer having good chemical stability. The materials constituting the power supply electrode and the ground electrode are suitably selected from metal materials such as chromium (Cr), gold (Au), titanium (Ti), molybdenum (Mo), aluminum (Al), nickel (Ni), indium (In), palladium (Pd), silver (Ag), copper (Cu), tin (Sn), and iron (Fe). The power supply electrode and the ground electrode may contain conductive ceramics, conductive resins, semiconductors, and the like.

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 joining member 50. The protective film 39 is provided by an insulating material. The protective film 39 covers a part of the power supply electrode (an area facing the opposing surface 43B of the lid member 40) and electrically insulates the power supply electrode from the lid member 40. Specifically, the protective film 39 covers at least a part of the wiring electrode 37a that connects the first side electrode 34a and the first electrode pad 33a, and covers at least a part of the wiring electrode 37b that connects the second side electrode 34b and the second electrode pad 33b. The protective film 39 is provided in an area outside the upper surface electrode 33c, and the upper surface electrode 33c is exposed from the protective film 39. The protective film 39 is, for example, a solder resist.

If the electrical conductivity of the bonding member 50 described later is sufficiently anisotropic and the electrical conductivity in the direction along the upper surface 31A of the base 31 is sufficiently low, the protective film 39 may be omitted. In this case, even if the bonding member 50 comes into contact with the power supply electrode, a short circuit between the quartz crystal vibration element 10 and the lid member 40 via the bonding member 50 is unlikely to occur.

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 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, for example, a cured product of a conductive adhesive containing a thermosetting resin, a photocurable resin, or the like.

Next, the cover member 40 will be described.
The cover member 40 is bonded 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 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 lid member 40 has a flat top wall portion 41 and a side wall portion 42 connected to the outer edge of the top wall portion 41. 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 lid member 40 may further have a flange portion connected to the tip of the side wall portion 42 on the base member 30 side and extending 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 43B facing the base member 30. The opposing surface 43B is a surface that extends along the upper surface 31A of the substrate 31 at the tip of the side wall portion 42 of the base member 30. The area of the opposing surface 43B 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 joining member 50 will be described.
The bonding member 50 bonds the base member 30 and the lid member 40. Specifically, the bonding member 50 bonds the protective film 39 and the opposing surface 43B, and bonds the upper electrode 33c and the opposing surface 43B. The bonding member 50 also seals the recess 49 that corresponds to the internal space. Specifically, 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 surrounding the quartz crystal vibration element 10.

The bonding member 50 is a conductive adhesive and electrically connects the ground electrode and the lid member 40. The conductivity of the bonding member 50 is anisotropic. Specifically, in the region between the upper electrode 33c and the opposing surface 43B, the electrical resistance of the bonding member 50 along the direction intersecting with the upper surface 31A of the base 31 is low, and the upper electrode 33c and the opposing surface 43B are electrically connected via the bonding member 50. On the other hand, the electrical resistance of the bonding member 50 along the upper surface 31A of the base 31 is high, and even when the bonding member 50 comes into contact with the power supply electrode, the power supply electrode and the lid member 40 are electrically insulated.

Next, a more detailed configuration of the joint portion formed by the joining member 50 will be described with reference to Figures 5 and 6. Figure 5 is an enlarged cross-sectional view of a quartz crystal unit including a ground electrode. Figure 6 is an enlarged cross-sectional view of a quartz crystal unit including a power supply electrode.

The conductive adhesive of the joining member 50 has a resin-based adhesive 51, a plurality of conductive fillers 52 dispersed in the resin-based adhesive 51, and a plurality of insulating fillers 53 dispersed in the resin-based adhesive 51.

The resin-based adhesive 51 is, for example, an epoxy-based thermosetting resin. The resin-based adhesive 51 may be an epoxy-based, vinyl-based, acrylic-based, urethane-based, imide-based, or silicone-based thermosetting resin. The resin-based adhesive 51 may include a photocurable resin.

The conductive filler 52 is, for example, a spherical filler in which a spherical resin core is covered with a metal film. The conductive filler 52 is deformable, and the conductive filler 52 sandwiched between the upper electrode 33c and the opposing surface 43B is deformed into an ellipsoid shape. With the deformation, the conductive filler 52 reliably contacts both the upper electrode 33c and the opposing surface 43B. As a result, the upper electrode 33c and the opposing surface 43B are electrically connected through the conductive filler 52. In addition, with the deformation, the contact area between the conductive filler 52 and the upper electrode 33c and the contact area between the conductive filler 52 and the opposing surface 43B increase. As a result, the electrical resistance between the conductive filler 52 and the upper electrode 33c decreases. The material of the resin core is, for example, a styrene-based resin or an acrylic-based resin. This makes it possible to suitably design the elastic modulus of the conductive filler 52. The material of the metal film is, for example, Ni. This makes it possible to prevent the metal film from peeling off from the resin core, and to prevent an increase in electrical resistance.

The resin core is not limited to styrene-based resin and acrylic-based resin as long as it is deformable. The metal film is not limited to Ni, and may be made of metal materials such as Au, Ag, Cu, Al, and Ti. The metal film may be a multi-layer film made of multiple metal layers. The conductive filler 52 may be a conductive material such as Cu, Ni, C, or Si processed into a spherical shape.

The insulating filler 53 adjusts the viscosity of the conductive adhesive before hardening and prevents the conductive adhesive from contacting the power supply electrode due to undesired spreading before hardening. The material of the insulating filler 53 is, for example, spherical silica. The material of the insulating filler 53 is not limited to the above, and may be an organic compound such as silicone, urethane, imide, epoxy, vinyl, amine, phenol, amino, acrylic, or styrene, or an inorganic compound such as titanium oxide, magnesium oxide, magnesium carbonate, magnesium hydroxide, alumina, boron nitride, aluminum nitride, glass fiber, or graphite.

The ratio of the volume of the conductive filler 52 to the total volume of the conductive adhesive of the bonding member 50 (hereinafter referred to as the "volume ratio") is not less than 3 vol % and not more than 18 vol %.
If the volume ratio is less than 3 vol%, the conductive filler 52 may not be present in the region between the upper electrode 33 c and the opposing surface 43 B, and electrical connection may not be obtained between the upper electrode 33 c and the opposing surface 43 B. In other words, if the volume ratio is 3 vol% or more, the occurrence rate of defective products in which the lid member 40 cannot be grounded can be reduced.
If the volume ratio is greater than 18 vol%, the conductive fillers 52 may approach or come into contact with each other, decreasing the electrical resistance of the bonding member 50 along the upper surface 31A of the base 31. In other words, if the volume ratio is 18 vol% or less, the occurrence rate of defective products in which the quartz crystal vibrating element 10 and the lid member 40 are short-circuited can be reduced.
In order to reduce the occurrence rate of defective products in which the lid member 40 cannot be grounded, it is more preferable that the volume ratio is 7 vol% or more. In order to reduce the occurrence rate of defective products in which the quartz crystal vibrating element 10 and the lid member 40 are short-circuited, it is more preferable that the volume ratio is 10 vol% or less.

When the conductive filler 52 is assumed to be a perfect sphere, the diameter (hereinafter referred to as "particle size R") satisfies the relationship 4 μm≦R≦15 μm.
The gap G1 between the upper electrode 33c and the opposing surface 43B varies by about 3.8 μm on average due to the waviness of the cover member 40. Therefore, when R<4 μm, the conductive filler 52 may not contact at least one of the upper electrode 33c and the opposing surface 43B. In other words, when 4 μm≦R, the occurrence rate of defective products in which the cover member 40 cannot be grounded can be reduced. Note that the variation in the gap G1 due to the waviness of the cover member 40 is a maximum of about 6 μm, so it is more desirable to satisfy 6 μm≦R.
Since the conductive filler 52 functions as a spacer, when 15 μm<R, the thickness of the bonding member 50 in the region between the upper electrode 33c and the opposing surface 43B increases, and the sealing performance may decrease. In other words, when R≦15 μm, the occurrence rate of defective products in which the frequency fluctuates due to leakage defects can be reduced.
The particle size R is an arithmetic mean particle size calculated from the particle size distribution obtained by the Coulter counter method of the resin core of the conductive filler 52. Since the thickness of the metal film of the conductive filler 52 is sufficiently smaller than the particle size of the resin core, the particle size of the resin core can be regarded as the particle size R of the conductive filler 52. Here, the thickness of the metal film of the conductive filler 52 is, for example, 10 nm or more and 500 nm or less. If the thickness of the metal film is smaller than 10 nm, the electrical resistance of the conductive filler 52 may increase. If the thickness of the metal film is larger than 500 nm, the metal film may inhibit the deformation of the conductive filler 52 or the metal film may peel off from the resin core. That is, if the thickness of the metal film is 10 nm or more and 500 nm or less, the occurrence rate of defective products in which the cover member 40 cannot be grounded can be reduced.

The width W of the opposing surface 43B in the short side direction and the particle size R of the conductive filler 52 satisfy the relationship 4 μm≦R≦W/2.
In order to establish conduction between the grounding electrode and the lid member 40, pressure is applied to the conductive filler 52 sandwiched between the upper electrode 33c and the opposing surface 43B. At this time, if W/2<R, the conductive filler 52 may be pushed out of the region between the upper electrode 33c and the opposing surface 43B. In other words, if R≦W/2, the occurrence rate of defective products in which the lid member 40 cannot be grounded can be reduced.
When R is 4 μm or less, the rate of occurrence of defective products in which the lid member 40 cannot be grounded can be reduced, as described above.

The diameter of the insulating filler 53 when it is assumed to be a perfect sphere (hereinafter referred to as "particle diameter r") and the particle diameter R of the conductive filler 52 satisfy the relationship r<R.
When R≦r, the insulating filler 53 may act as a spacer and inhibit the deformation of the conductive filler 52. For example, when the elastic modulus of the insulating filler 53 is greater than that of the conductive filler 52, if R=r, the deformation of the conductive filler 52 is inhibited by the insulating filler 53. Even if the elastic modulus of the insulating filler 53 is smaller than that of the conductive filler 52, if R<<r, the deformation of the conductive filler 52 is inhibited by the insulating filler 53. Therefore, when r<R, the occurrence rate of defective products in which the cover member 40 cannot be grounded can be reduced.
The particle size r is the median diameter D50 calculated from the particle size distribution obtained by the Microtrack method.

The particle size R and the particle size r satisfy the relationship R/20≦r≦R×8/10.
When r<R/20, the insulating filler 53 may penetrate between the conductive filler 52 and the upper electrode 33c, hindering contact between the conductive filler 52 and the upper electrode 33c. Similarly, contact between the conductive filler 52 and the opposing surface 43B may be hindered. In other words, when R/20≦r, the occurrence rate of defective products in which the cover member 40 cannot be grounded can be reduced.
If R×8/10<r, the insulating filler 53 may function as a spacer to inhibit deformation of the conductive filler 52 in the region between the upper electrode 33c and the opposing surface 43B. In other words, if r≦R×8/10, the occurrence rate of defective products in which the lid member 40 cannot be grounded can be reduced.
From the viewpoint of reducing the rate of defective products in which the lid member 40 cannot be grounded, it is preferable that the particle size R and the particle size r further satisfy the relationship R/10≦r. It is also preferable that the particle size R and the particle size r further satisfy the relationship r≦R/2.

A gap G1 between the upper electrode 33c and the opposing surface 43B, a gap G2 between the protective film 39 and the opposing surface 43B, and a particle size R of the conductive filler 52 satisfy the relationship G1<R<G2.
When R≦G1, the conductive filler 52 may not contact at least one of the upper electrode 33c and the opposing surface 43B. In other words, when G1<R, the occurrence rate of defective products in which the lid member 40 cannot be grounded can be reduced.
When G2≦R, the conductive filler 52 sandwiched between the protective film 39 and the opposing surface 43B is deformed. When the conductive filler 52 sandwiched between the upper electrode 33c and the opposing surface 43B is deformed, a part of the conductive filler 52 is pushed out from the region between the protective film 39 and the opposing surface 43B. This may cause the conductive fillers 52 to approach each other in undesired regions, decreasing the electrical resistance of the bonding member 50 in the direction along the upper surface 31A of the base 31. In other words, when R<G2, the occurrence rate of defective products in which the quartz crystal vibrating element 10 and the lid member 40 are short-circuited can be reduced.

The gaps G1 and G2 satisfy the relationship 0≦G2−G1≦13 μm.
When G2-G1<0, i.e., when G2<G1, the conductive filler 52 located in the region between the protective film 39 and the opposing surface 43B functions as a spacer, which may inhibit sufficient deformation of the conductive filler 52 in the region between the upper electrode 33c and the opposing surface 43B. In other words, when 0≦G2-G1, the occurrence rate of defective products in which the lid member 40 cannot be grounded can be reduced.
When 13 μm<G2−G1, the sealing performance may decrease with an increase in the film thickness of the bonding member 50 in the region between the protective film 39 and the opposing surface 43B. In other words, when G2−G1≦13 μm, the occurrence rate of defective products in which the frequency fluctuates due to leakage defects can be reduced.

The gap G2 satisfies the relationship 2 μm≦G2≦20 μm.
The gap G2 is limited by the grain size R. Therefore, to reduce the gap G2, it is necessary to reduce the grain size R. When G2<2 μm, the grain size R is too small, and the conductive filler 52 may not contact at least one of the upper surface electrode 33c and the opposing surface 43B due to the variation in the gap G1 caused by the waviness of the cover member 40. In other words, when 2 μm≦G2, the occurrence rate of defective products in which the cover member 40 cannot be grounded can be reduced.
When 20 μm<G2, the sealing performance may decrease with an increase in the film thickness of the bonding member 50 in the region between the protective film 39 and the opposing surface 43B. In other words, when G2≦20 μm, the occurrence rate of defective products in which the frequency fluctuates due to leakage defects can be reduced.

Next, examples and comparative examples will be described with reference to Figures 7 and 8. Figure 7 is a table showing the ground failure rate when the width W and particle size R are changed. Figure 8 is a table showing the ground failure rate when the particle size R and particle size r are changed.

7 are the crystal resonators 1 according to the present embodiment, in which the additive rate of the conductive filler 52 is constant and the particle size R is varied. The "additive rate of the conductive filler 52" is the ratio of the weight of the conductive filler 52 to the total weight of the conductive adhesive.
(Comparative Example 1)
R=3.0 μm, and the additive rate of the conductive filler 52 is 10 wt %.
Example 1
R=5 μm, and the additive rate of the conductive filler 52 is 10 wt %.
Example 2
R=10 μm, and the additive rate of the conductive filler 52 is 10 wt %.
Example 3
R=15 μm, and the additive rate of the conductive filler 52 is 10 wt %.
(Comparative Example 2)
R=20 μm, and the additive rate of the conductive filler 52 is 10 wt %.

For each crystal unit 1, the occurrence rate of defective products in which the cover member 40 and the power supply electrode are not electrically connected (hereinafter referred to as the "grounding failure rate") and the occurrence rate of defective products in which the frequency fluctuates due to leakage failure (hereinafter referred to as the "leakage failure rate") were measured. The number of samples measured for each was 20. In determining the grounding failure rate, products with an electrical resistance between the grounding electrode and the cover member 40 of 10 Ω or less were determined to be good products, and products with an electrical resistance greater than 10 Ω were determined to be defective products. A grounding failure rate of 5% or less was determined to be ◯, and a failure rate of more than 5% was determined to be ×. In determining the leakage failure rate, products in which Galden (registered trademark, manufactured by Solvay) does not penetrate into the interior even when immersed in Galden and reduced pressure was determined to be good products, and products in which Galden penetrates into the interior when immersed in Galden and reduced pressure was determined to be defective products. A leakage failure rate of 5% or less was determined to be ◯, and a failure rate of more than 5% was determined to be ×.

In Comparative Example 1, which satisfied R<4 μm, the leakage defect rate was low but the grounding defect rate was high, and the occurrence rate of defective products could not be sufficiently reduced. In Comparative Example 2, which satisfied 15 μm<R, the grounding defect rate was low but the leakage defect rate was high, and the occurrence rate of defective products could not be sufficiently reduced. In Examples 1 to 3, which satisfied 4 μm≦R≦15 μm, both the grounding defect rate and leakage defect rate were low, and the occurrence of defective products was suppressed.

The quartz crystal resonators according to each of Examples 4 to 6 and Comparative Examples 3 and 4 in FIG. 8 are the quartz crystal resonators 1 according to the present embodiment, with the gaps G1 and G2 being changed.
Example 4
G1 = 15 μm, G2 = 20 μm, G2 - G1 = 5 μm
Example 5
G1 = 10 μm, G2 = 20 μm, G2 - G1 = 10 μm
Example 6
G1 = 7 μm, G2 = 20 μm, G2 - G1 = 13 μm
(Comparative Example 3)
G1 = 7 μm, G2 = 22 μm, G2 - G1 = 15 μm
(Comparative Example 4)
G1 = 15 μm, G2 = 28 μm, G2 - G1 = 13 μm

The leakage defect rate was measured for each crystal unit 1. The number of samples measured for each was 20. In judging the leakage defect rate, products in which Galden did not penetrate when immersed in Galden and reduced pressure were judged to be good products, and products in which Galden penetrated when immersed in Galden and reduced pressure were judged to be defective products. A leakage defect rate of 5% or less was rated as "good," and a leakage defect rate of more than 5% was rated as "bad."

In Comparative Example 3, which satisfied 13 μm < G2 - G1, the leakage defect rate was high and the incidence of defective products could not be sufficiently reduced. In Comparative Example 4, which satisfied 0 ≦ G2 - G1 ≦ 13 μm but 20 μm < G2, the leakage defect rate was high and the incidence of defective products could not be sufficiently reduced.

As described above, in this embodiment, the relationship 4 μm≦R≦15 μm is satisfied.
This allows the conductive filler 52 to be in contact with both the upper surface electrode 33c and the opposing surface 43B while reducing the thickness of the bonding member 50. Therefore, the rate of occurrence of defective products in which the cover member 40 cannot be grounded can be reduced, and the rate of occurrence of defective products in which the frequency fluctuates due to leakage defects can also be reduced.

In another embodiment, the relationship 0≦G2−G1≦13 μm is satisfied.
This allows the conductive filler 52 to be in contact with both the upper surface electrode 33c and the opposing surface 43B while reducing the thickness of the bonding member 50. Therefore, the rate of occurrence of defective products in which the cover member 40 cannot be grounded can be reduced, and the rate of occurrence of defective products in which the frequency fluctuates due to leakage defects can also be reduced.

Below, some or all of the embodiments of the present invention will be described, and their effects will be explained. 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 oscillator comprising: a quartz crystal vibration element; a base member on which the quartz crystal vibration element is mounted; and a lid member of a conductive material bonded to the base member with a bonding member made of a conductive adhesive sandwiched therebetween, and forming an internal space between the lid member and the base member and in which the quartz crystal vibration element is disposed, wherein the lid 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 facing the base member, the base member being provided with a power supply electrode to which the quartz crystal vibration element is connected and a grounding electrode used for grounding, the grounding electrode being electrically connected to the lid member via the bonding member, the conductive adhesive comprising a resin-based adhesive and a conductive filler dispersed in the resin-based adhesive, and a particle size R of the conductive filler satisfying the relationship of 4 μm≦R≦15 μm.
According to this, the lid member, which can provide an electromagnetic shielding function by being grounded, can reduce noise caused by the ingress and egress of electromagnetic waves. Also, the thickness of the joining member can be reduced while the conductive filler is in contact with both the power supply electrode and the lid member. Therefore, the occurrence rate of defective products in which the lid member cannot be grounded can be reduced, while the occurrence rate of defective products in which the frequency fluctuates due to leakage defects can also be reduced.

In one embodiment, the base member is provided with a protective film made of an insulating material that covers at least the area of the power supply electrode that faces the opposing surface, the protective film is in contact with the joining member, and the gap G1 between the ground electrode and the opposing surface and the gap G2 between the protective film and the opposing surface satisfy the relationship 0 < G2 - G1 < 13 μm.

According to another aspect of the present invention, there is provided a quartz crystal resonator comprising: a quartz crystal resonator element; a base member on which the quartz crystal resonator element is mounted; and a lid member of a conductive material that is bonded to the base member with a bonding member made of a conductive adhesive sandwiched therebetween and that forms an internal space in which the quartz crystal resonator element is disposed between the lid member and the base 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 base member being provided with a power supply electrode to which the quartz crystal resonator element is connected and a grounding electrode used for grounding, the grounding electrode being electrically connected to the lid member via the bonding member, the conductive adhesive having a resin-based adhesive and a conductive filler dispersed in the resin-based adhesive, the base member being provided with a protective film made of an insulating material that covers at least an area of the power supply electrode that faces the opposing surface, the protective film being in contact with the bonding member, and a gap G1 between the grounding electrode and the opposing surface and a gap G2 between the protective film and the opposing surface satisfy the relationship 0≦G2−G1≦13 μm.
According to this, the lid member, which can provide an electromagnetic shielding function by being grounded, can reduce noise caused by the ingress and egress of electromagnetic waves. Also, the thickness of the joining member can be reduced while the conductive filler is in contact with both the power supply electrode and the lid member. Therefore, the occurrence rate of defective products in which the lid member cannot be grounded can be reduced, while the occurrence rate of defective products in which the frequency fluctuates due to leakage defects can also be reduced.

As one aspect, the gap G2 between the protective film and the facing surface satisfies the relationship 2 μm≦G2≦20 μm.
This allows the thickness of the bonding member to be reduced while the conductive filler is in contact with both the power supply electrode and the lid member, thereby reducing the rate of defective products in which the lid member cannot be grounded and also reducing the rate of defective products in which the frequency fluctuates due to leakage defects.

As one embodiment, the gap G2 between the protective film and the facing surface and the particle size R of the conductive filler satisfy the relationship R<G2.
This can prevent conductive fillers from coming close to each other in undesired areas, thereby reducing the incidence of defective products in which the quartz crystal vibrating element and the lid member are short-circuited.

In one embodiment, the conductive filler has a spherical resin core and a metal film covering the resin core.

In one embodiment, the resin core is a styrene-based resin or an acrylic-based resin, and the metal film is nickel.

In one embodiment, the resin-based adhesive is an epoxy-based thermosetting resin.

In one embodiment, the conductive adhesive further includes insulating filler dispersed in the resin-based adhesive, and the particle size R of the conductive filler and the particle size r of the insulating filler satisfy the relationship r<R.
This can suppress the insulating filler from hindering the deformation of the conductive filler, thereby reducing the incidence of defective products in which the lid member cannot be grounded.

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 ( _BaTiO3 ), lead titanate ( _PbTiO3 ), lead zirconate titanate (Pb(ZrxTi1 _{- x} )O3; PZT), aluminum nitride (AlN), lithium niobate ( _LiNbO3 ), lithium metaniobate ( _LiNb2O6 ), _bismuth titanate ( _Bi4Ti3O12 ), lithium tantalate ( _LiTaO3 ), lithium tetraborate ( _Li2B4O7 ), langasite ( _La3Ga5SiO14 ), and _tantalum pentoxide _{( Ta2O5} ). _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 that can suppress noise while reducing the occurrence of defective products.

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 thereof, 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,
30...base member,
31...base,
33a, 33b...electrode pads,
33c...top electrode,
34a to 34d: side electrodes,
35a to 35d: external electrodes,
39...protective film,
40...Cover member,
41...Ceiling wall portion,
42...side wall portion,
43B...opposing surface,
50...Joining member,
51...resin adhesive,
52...conductive filler,
53...insulating filler,

Claims (10)

A piezoelectric vibration element;
A base member on which the piezoelectric vibration element is mounted;
a cover member made of a conductive material that defines an internal space in which the piezoelectric vibration element is disposed between the cover member and the base member;
a joining member that joins the base member and the lid member and is provided by a conductive adhesive;
Equipped with
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 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 electrically connected to the lid member via the joining member;
the conductive adhesive includes a resin-based adhesive and a conductive filler dispersed in the resin-based adhesive,
The particle diameter R of the conductive filler is
4 μm≦R≦15 μm
Fulfilling the relationship,
a protective film made of an insulating material is provided on the base member and covers at least a region of the power supply electrode facing the facing surface, the protective film being in contact with the bonding member;
A gap G1 between the ground electrode and the facing surface, and a gap G2 between the protective film and the facing surface are
0≦G2−G1≦13 μm
A piezoelectric vibrator that satisfies the relationship. A piezoelectric vibration element;
A base member on which the piezoelectric vibration element is mounted;
a cover member made of a conductive material that defines an internal space in which the piezoelectric vibration element is disposed between the cover member and the base member;
a joining member that joins the base member and the lid member and is provided by a conductive adhesive;
Equipped with
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 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 electrically connected to the lid member via the joining member;
the conductive adhesive includes a resin-based adhesive and a conductive filler dispersed in the resin-based adhesive,
a protective film made of an insulating material is provided on the base member and covers at least a region of the power supply electrode facing the facing surface, the protective film being in contact with the bonding member;
A gap G1 between the ground electrode and the facing surface, and a gap G2 between the protective film and the facing surface are
0≦G2−G1≦13 μm
A piezoelectric vibrator that satisfies the relationship. The gap G2 between the protective film and the facing surface is
2 μm≦G2≦20 μm
Satisfy the relationship
3. The piezoelectric vibrator according to claim 1 or 2. The gap G2 between the protective film and the facing surface and the particle size R of the conductive filler are
R < G2
Satisfy the relationship
The piezoelectric vibrator according to claim 1 . The conductive filler has a spherical resin core and a metal film covering the resin core.
The piezoelectric vibrator according to claim 1 . The resin core is a styrene-based resin or an acrylic-based resin,
The metal film is nickel.
The piezoelectric vibrator according to claim 5 . The resin adhesive is an epoxy thermosetting resin.
The piezoelectric vibrator according to claim 1 . The conductive adhesive further comprises an insulating filler dispersed in the resin-based adhesive,
The particle diameter R of the conductive filler and the particle diameter r of the insulating filler are
r < R
Satisfy the relationship
The piezoelectric vibrator according to claim 1 . A portion of the conductive filler is deformed by being sandwiched between the ground electrode and the cover member.
The piezoelectric vibrator according to claim 1 . The power supply electrode is
an electrode pad provided on an upper surface of the base member facing the lid member and surrounded by the bonding member when the upper surface is viewed in plan;
a side electrode provided on a side surface of the base member;
a wiring electrode provided on the upper surface and electrically connecting the electrode pad and the side electrode;
having
The piezoelectric vibrator according to claim 1 .

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