阅读说明：本技术 压电振动器件 (Piezoelectric vibration device ) 是由 藤原宏树 于 2019-03-04 设计创作，主要内容包括：AT切石英晶体片上形成的贯穿孔具有从周边部朝着中心部的通孔(71)倾斜的倾斜面(72),倾斜面(72)上存在：从通孔(71)朝着贯穿孔的周边部向－Z’方向侧及+X方向侧延伸的第一结晶面(S1)；从通孔(71)朝着贯穿孔的周边部向－Z’方向侧及+X方向侧延伸,并在第一结晶面(S1)的+Z’方向侧及+X方向侧与该第一结晶面接触的第二结晶面(S2)；及在第二结晶面(S2)的+X方向侧与该第二结晶面接触并与AT切石英晶体片的主面接触的第三结晶面(S3),三个结晶面(S1～S3)与AT切石英晶体片的主面之间形成有补偿面(Sc),该补偿面阻碍第一棱线(L1)及第二棱线(L2)到达AT切石英晶体片的主面。(The through-hole formed in the AT-cut quartz crystal piece has an inclined surface (72) inclined from the peripheral portion toward the through-hole (71) in the central portion, and the inclined surface (72) has: a first crystal plane (S1) extending from the through hole (71) toward the peripheral portion of the through hole in the-Z' direction and the + X direction; a second crystal surface (S2) extending from the through hole (71) toward the peripheral portion of the through-hole in the-Z 'direction and the + X direction, and contacting the first crystal surface (S1) on the + Z' direction side and the + X direction side; and a third crystal plane (S3) which is in contact with the second crystal plane on the + X direction side of the second crystal plane (S2) and which is in contact with the main surface of the AT-cut quartz crystal piece, wherein a compensation plane (Sc) is formed between the three crystal planes (S1-S3) and the main surface of the AT-cut quartz crystal piece, and the compensation plane prevents the first ridge line (L1) and the second ridge line (L2) from reaching the main surface of the AT-cut quartz crystal piece.)

1. A piezoelectric resonator device provided with a piezoelectric vibrating reed, a first sealing member covering one principal surface side of the piezoelectric vibrating reed, and a second sealing member covering the other principal surface side of the piezoelectric vibrating reed, the first sealing member being bonded to the piezoelectric vibrating reed; the second sealing member is bonded to the piezoelectric vibrating reed to form an internal space hermetically sealing a vibrating portion of the piezoelectric vibrating reed including a first excitation electrode and a second excitation electrode, and is characterized in that:

the piezoelectric vibrating reed includes a vibrating portion, a holding portion for holding the vibrating portion, and an outer frame portion surrounding an outer periphery of the vibrating portion and holding the holding portion,

the first sealing member is composed of an AT-cut quartz crystal piece,

the first sealing member is provided with a through hole provided on the + Z' -direction side of the inner peripheral edge portion of the outer frame portion of the piezoelectric vibrating reed,

the through hole has an inclined surface inclined from the peripheral portion toward the through hole at the center portion on the main surface opposite to the bonding surface bonded to the piezoelectric vibrating reed,

the inclined surface is arranged on the upper surface of the inclined surface,

a first crystal plane extending from the through hole to a-Z' direction side and a + X direction side of the peripheral portion of the through hole;

a second crystal plane extending from the through hole toward a peripheral portion of the through hole in a-Z 'direction and a + X direction, and contacting the first crystal plane on a + Z' direction side and a + X direction side of the first crystal plane; and

a third crystal plane in contact with the second crystal plane on the + X direction side of the second crystal plane and in contact with the main surface of the first sealing member,

a compensation surface is formed between the three crystal surfaces and the main surface of the first sealing member, the compensation surface preventing an edge line between the first crystal surface and the second crystal surface and an edge line between the second crystal surface and the third crystal surface from reaching the main surface of the first sealing member.

2. A piezoelectric vibrator element as claimed in claim 1, wherein:

the compensation plane is in contact with only the three crystal planes and not with other crystal planes in the inclined plane.

3. A piezoelectric resonator device according to claim 1 or 2, wherein:

the distance between two points at both ends of the boundary line between the compensation surface and the main surface of the first seal member is 5% to 30% of the maximum diameter of the through hole.

4. A piezoelectric resonator device provided with a piezoelectric vibrating reed, a first sealing member covering one principal surface side of the piezoelectric vibrating reed, and a second sealing member covering the other principal surface side of the piezoelectric vibrating reed, the first sealing member being bonded to the piezoelectric vibrating reed; the second sealing member is bonded to the piezoelectric vibrating reed to form an internal space hermetically sealing a vibrating portion of the piezoelectric vibrating reed including a first excitation electrode and a second excitation electrode, and is characterized in that:

the piezoelectric vibrating reed includes a vibrating portion, a holding portion for holding the vibrating portion, and an outer frame portion surrounding an outer periphery of the vibrating portion and holding the holding portion,

the first sealing member is composed of an AT-cut quartz crystal piece,

the first sealing member is provided with a through hole provided on the + Z' -direction side of the inner peripheral edge portion of the outer frame portion of the piezoelectric vibrating reed,

the through hole has an inclined surface inclined from the peripheral portion toward the through hole at the center portion on the main surface opposite to the bonding surface bonded to the piezoelectric vibrating reed,

any ridge line between the crystal planes existing in the inclined plane does not intersect on the outer periphery of the through-hole.

Technical Field

The present invention relates to a piezoelectric vibration device.

Background

In recent years, various electronic devices have been developed to have higher operating frequencies and smaller packages (particularly, smaller packages). Therefore, with the increase in frequency and the reduction in size of the package, there is a demand for piezoelectric resonator devices (e.g., crystal resonators, crystal oscillators, etc.) that can also cope with the increase in frequency and the reduction in size of the package.

The case of such a piezoelectric vibration device is constituted by an approximately rectangular parallelepiped package. The package includes a first sealing member and a second sealing member made of, for example, glass or quartz crystal, and a piezoelectric vibrating reed made of, for example, quartz crystal and having excitation electrodes formed on both main surfaces thereof, and the first sealing member and the second sealing member are laminated and bonded via the piezoelectric vibrating reed. Further, a vibrating portion (excitation electrode) of the piezoelectric vibrating reed disposed in the package (internal space) is hermetically sealed (for example, patent document 1). Hereinafter, the laminated structure of such a piezoelectric resonator device is referred to as a sandwich structure.

In recent years, further reduction in area has been demanded for piezoelectric resonator devices having a sandwich structure. However, the inventors of the present invention have found that, when the first sealing member is formed of an AT-cut quartz crystal piece while reducing the area of the piezoelectric resonator device having a sandwich structure, cracks are likely to occur in the through-hole formed in the first sealing member.

Here, fig. 15 is a sectional view showing a schematic structure of a piezoelectric resonator device 500 having a sandwich structure. The piezoelectric resonator device 500 includes a crystal resonator element 510, a first sealing member 520, and a second sealing member 530, wherein the crystal resonator element 510 is bonded to the first sealing member 520; the crystal resonator element 510 is bonded to the second sealing member 530, thereby forming a substantially rectangular parallelepiped package.

The crystal resonator plate 510 includes a vibrating portion 511 having a pair of excitation electrodes (not shown) formed on both surfaces thereof, an outer frame portion 512 surrounding the outer periphery of the vibrating portion 511, and a holding portion 513 holding the vibrating portion 511 by coupling the vibrating portion 511 to the outer frame portion 512. That is, the crystal resonator plate 510 is configured by integrally forming the vibrating portion 511, the outer frame portion 512, and the holding portion 513.

In the piezoelectric resonator device 500 with a reduced size, the through-hole 550 is usually used to provide electrical conduction between the electrode and the wiring. In the case where the through-hole 550 is provided in the first sealing member 520, the through-hole 550 is formed in a region overlapping the outer frame portion 512 of the crystal resonator plate 510.

As shown in fig. 16(a), when the piezoelectric vibrator device 500 is operated or when an IC chip or the like is mounted on the piezoelectric vibrator device 500, an external force F1 may act on the vicinity of the central portion of the first sealing member 520 from above (force point P1). At this time, based on the lever principle, the inner peripheral edge portion of the outer frame portion 512 of the crystal resonator plate 510 becomes the fulcrum P2, the inner peripheral edge portion of the through-hole 550 becomes the operating point P3, and the stress F3 is generated at the operating point P3.

When the piezoelectric resonator device 500 is further reduced in area, the width of the outer frame portion 512 is reduced as shown in fig. 16 (b). In the piezoelectric vibrator device 500 having the narrowed width of the outer frame portion 512, when the stress F3 is generated in the through hole 550 based on the principle of leverage, the stress F3 may be much larger than the stress F3 in fig. 16 (a). The reason for this is that, when the width of the outer frame portion 512 is narrowed, the distance between the fulcrum P2 and the operating point P3 is reduced with respect to the distance between the force point P1 and the fulcrum P2.

As described above, as the area of the piezoelectric vibration device is reduced (the width of the outer frame portion in the crystal resonator plate is reduced), the stress generated in the edge portion of the through hole is increased, and the through hole is likely to be cracked.

[ patent document 1 ] Japanese patent laid-open No. 2010-252051

Disclosure of Invention

In view of the above, an object of the present invention is to provide a piezoelectric resonator device having a sandwich structure, which can alleviate stress concentration in a through-hole and prevent cracks from occurring.

In order to solve the above-described problems, a piezoelectric resonator device according to a first aspect of the present invention includes a piezoelectric resonator element, a first sealing member covering one principal surface side of the piezoelectric resonator element, and a second sealing member covering the other principal surface side of the piezoelectric resonator element, wherein the first sealing member is bonded to the piezoelectric resonator element; the second sealing member is bonded to the piezoelectric vibrating reed to form an internal space hermetically sealing a vibrating portion of the piezoelectric vibrating reed including a first excitation electrode and a second excitation electrode, and the piezoelectric vibrating reed is characterized in that: the piezoelectric vibrating reed includes a vibrating portion, a holding portion that holds the vibrating portion, and an outer frame portion that surrounds an outer periphery of the vibrating portion and holds the holding portion, the first sealing member is formed of an AT-cut quartz crystal piece, the first sealing member is provided with a through hole that is provided on a + Z 'direction side of an inner peripheral edge portion of the outer frame portion of the piezoelectric vibrating reed, the through hole has an inclined surface that is inclined from a peripheral portion toward a through hole in a central portion on a main surface on an opposite side of a bonding surface to which the piezoelectric vibrating reed is bonded, and the inclined surface has a first bonding surface that extends from the through hole toward a peripheral portion of the through hole toward a-Z' direction side and a + X direction side; a second crystal plane extending from the through hole toward a peripheral portion of the through hole in a-Z 'direction and a + X direction, and contacting the first crystal plane on a + Z' direction side and a + X direction side of the first crystal plane; and a third crystal plane in contact with the second crystal plane on the + X direction side of the second crystal plane and in contact with the main surface of the first seal member, wherein a compensation plane is formed between the three crystal planes and the main surface of the first seal member, the compensation plane preventing a ridge line between the first crystal plane and the second crystal plane and a ridge line between the second crystal plane and the third crystal plane from reaching the main surface of the first seal member.

With the above structure, stress concentration in the through hole formed in the piezoelectric resonator device having the sandwich structure can be relaxed, and thus generation of cracks can be prevented. That is, in the conventional through-hole, two ridge lines appearing on the inner wall surface of the through-hole reach the main surface of the AT-cut quartz crystal piece, intersect on the outer periphery of the through-hole to become stress concentration points, and further become starting points of crack generation. In contrast, in the through-hole having the above-described structure, since the compensation surface is formed at the stress concentration portion, the two ridge lines cannot intersect at the outer peripheral edge portion of the through-hole. As a result, the generation of stress concentration points can be prevented, and the generation of cracks starting from the stress concentration points can be prevented.

In the piezoelectric resonator device, it is preferable that the compensation surface is in contact with only the three crystal surfaces and not in contact with the other crystal surfaces in the inclined surface.

With the above configuration, the compensation surface is formed within a desired minimum, and thus it is possible to prevent other unnecessary crystal surfaces from being formed in the through-hole. Since an increase in the number of unnecessary crystal planes in the through-hole causes an increase in on-resistance, the formation of the unnecessary crystal planes can be restricted, thereby avoiding the above-mentioned problem.

In the piezoelectric vibration device, a distance between two points at both ends of an intersection line between the compensation surface and the main surface of the first sealing member is preferably 5% or more and 30% or less of a maximum diameter of the through hole.

With the above structure, the compensation surface in the through hole can have an appropriate size. If the value of the distance between the two points is 5% or less of the maximum diameter of the through-hole, the compensation surface is too small, and the effect of sufficiently relaxing the stress concentration cannot be obtained. On the other hand, if the value of the distance between the two points is 30% or more of the maximum diameter of the through hole, the compensation surface becomes too large, and an unnecessary increase in crystal surface causes an increase in on-resistance.

In order to solve the above-described problems, a piezoelectric resonator device according to a second aspect of the present invention includes a piezoelectric resonator element, a first sealing member covering one principal surface side of the piezoelectric resonator element, and a second sealing member covering the other principal surface side of the piezoelectric resonator element, wherein the first sealing member is bonded to the piezoelectric resonator element; the second sealing member is bonded to the piezoelectric vibrating reed to form an internal space hermetically sealing a vibrating portion of the piezoelectric vibrating reed including a first excitation electrode and a second excitation electrode, and the piezoelectric vibrating reed is characterized in that: the piezoelectric vibrating reed includes a vibrating portion, a holding portion that holds the vibrating portion, and an outer frame portion that surrounds an outer periphery of the vibrating portion and holds the holding portion, the first sealing member is formed of an AT-cut quartz crystal piece, the first sealing member is provided with a through hole that is provided on a + Z' -direction side of an inner peripheral edge portion of the outer frame portion of the piezoelectric vibrating reed, the through hole has an inclined surface that is inclined from a peripheral portion toward a through hole in a central portion on a main surface on an opposite side of a bonding surface to which the piezoelectric vibrating reed is bonded, and any ridge line between crystal surfaces existing in the inclined surface does not intersect on the outer periphery of the through hole.

With the above structure, in the through-hole formed in the piezoelectric resonator device of the sandwich structure, any ridge lines between the crystal planes do not intersect on the outer periphery of the through-hole. As a result, the generation of stress concentration points can be prevented, and the generation of cracks starting from the stress concentration points can be prevented.

The invention has the following effects:

the piezoelectric vibrator of the present invention can prevent the generation of stress concentration points in the through-holes, and can prevent the generation of cracks starting from the stress concentration points.

Drawings

Fig. 1 is a diagram showing an embodiment of the present invention, that is, a schematic configuration diagram schematically showing each component of a crystal oscillator.

Fig. 2 is a schematic plan view of the first main surface side of the first sealing member of the crystal oscillator.

Fig. 3 is a schematic plan view of the second main surface side of the first sealing member of the crystal oscillator.

Fig. 4 is a schematic plan view of the first main surface side of the crystal resonator plate of the crystal oscillator.

Fig. 5 is a schematic plan view of the second main surface side of the crystal resonator plate of the crystal oscillator.

Fig. 6 is a schematic plan view of the first main surface side of the second sealing member of the crystal oscillator.

Fig. 7 is a schematic plan view of the second main surface side of the second sealing member of the crystal oscillator.

Fig. 8(a) is a cross-sectional view showing the shape of a through hole in the case where a through hole is formed in an AT-cut quartz crystal wafer by etching using a circular mask.

Fig. 8(b) is a plan view showing the shape of a through hole in the case where a through hole is formed in an AT-cut quartz crystal wafer by etching using a circular mask.

Fig. 9(a) is a diagram showing the shape of the through-hole according to the first embodiment, that is, an enlarged plan view of the vicinity of the compensation surface formed in the through-hole.

Fig. 9(b) is a diagram showing the shape of the through-hole according to the first embodiment, that is, an enlarged perspective view of the vicinity of the compensation surface formed in the through-hole as viewed obliquely from above.

Fig. 10 is a plan view showing the shape of a mask used for forming the through hole in fig. 9.

Fig. 11 is a diagram for explaining an appropriate size of the compensation surface in the through hole of fig. 9.

Fig. 12(a) is a plan view of the through-hole according to the second embodiment.

Fig. 12(b) is a sectional view taken along the line a-a in fig. 12 (a).

Fig. 13(a) is a cross-sectional view showing a process of forming the through-hole shown in fig. 12(a), that is, a cross-sectional view showing a state after the first etching is completed.

Fig. 13(b) is a sectional view showing a process of forming the through-hole shown in fig. 12(a), that is, a sectional view showing a state after the second etching is completed.

Fig. 14(a) is a plan view showing the shape of a mask used for manufacturing the through-hole shown in fig. 12 (a).

Fig. 14(b) is a plan view showing the shape of a mask used for manufacturing the through-hole shown in fig. 12 (a).

Fig. 15 is a sectional view showing a schematic structure of a piezoelectric resonator device having a sandwich structure.

Fig. 16(a) is a diagram illustrating the principle of stress generated in the through-hole in the case where the piezoelectric resonator device of the sandwich structure has a normal size.

Fig. 16(b) is a diagram showing the principle of stress generation in the through-hole in the case where the piezoelectric resonator device has a small area size in the piezoelectric resonator device having the sandwich structure.

Detailed Description

< embodiment one >

Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. In the first embodiment described below, a case where the piezoelectric vibrator device to which the present invention is applied is a crystal oscillator will be described.

-crystal oscillator-

First, a basic configuration of the crystal oscillator 100 according to the first embodiment will be described. As shown in fig. 1, the crystal oscillator 100 includes a crystal resonator element (piezoelectric resonator element) 10, a first sealing member 20, a second sealing member 30, and an IC chip 40. In the crystal oscillator 100, a crystal resonator plate 10 is bonded to a first sealing member 20; the crystal resonator element 10 is bonded to the second sealing member 30, thereby forming a package having a substantially rectangular parallelepiped sandwich structure. That is, in the crystal oscillator 100, the two main surfaces of the crystal resonator element 10 are bonded to the first sealing member 20 and the second sealing member 30, respectively, to form an internal space of the package, and the vibrating portion 11 (see fig. 4 and 5) is hermetically sealed in the internal space.

Further, an IC chip 40 is mounted on the main surface of the first sealing member 20 on the opposite side of the bonding surface to the crystal resonator plate 10. The IC chip 40 as the electronic component element is a single-chip integrated circuit element constituting an oscillation circuit together with the crystal resonator plate 10.

The crystal oscillator 100 according to the first embodiment has a package size of, for example, 1.0 × 0.8mm, and is reduced in size and height. Further, with the miniaturization, the electrical conduction of the electrodes is realized by through-holes described later without forming castellations in the package.

Next, the respective members of the crystal resonator element 10, the first sealing member 20, and the second sealing member 30 in the crystal oscillator 100 will be described with reference to fig. 1 to 7. Here, each member which is not yet joined and is configured as a single body will be described. Fig. 2 to 7 show only one example of the structure of the crystal resonator element 10, the first sealing member 20, and the second sealing member 30, and do not limit the present invention.

As shown in fig. 4 and 5, the crystal resonator element 10 is a piezoelectric substrate made of quartz crystal, and both main surfaces (a first main surface 101 and a second main surface 102) thereof are processed (mirror-finished) to be flat and smooth surfaces. In the first embodiment, an AT-cut quartz crystal piece that performs thickness shear vibration is used as the crystal resonator plate 10. In the crystal resonator plate 10 shown in fig. 4 and 5, the two main surfaces 101 and 102 of the crystal resonator plate 10 are on the XZ' plane. In the XZ' plane, a direction parallel to the short side direction of the crystal resonator plate 10 is an X-axis direction; a direction parallel to the longitudinal direction of the crystal resonator plate 10 is a Z' -axis direction. The AT cut is a processing technique in which, among an electric axis (X axis), a mechanical axis (Y axis), and an optical axis (Z axis) which are three crystal axes of an artificial quartz crystal, the crystal is cut AT an angle of 35 ° 15' around the X axis with respect to the Z axis. In the AT-cut quartz crystal wafer, the X axis is consistent with the crystal axis of the quartz crystal. The Y ' axis and the Z ' axis are axes inclined by approximately 35 ° 15 ' (the cut angle may be slightly varied within a range for adjusting the frequency-temperature characteristics of the AT-cut crystal resonator plate) with respect to the Y axis and the Z axis of the crystal axis of the quartz crystal, respectively. The Y 'axis direction and the Z' axis direction are equivalent to the cutting direction when the AT cut quartz crystal piece is cut.

A pair of excitation electrodes (a first excitation electrode 111 and a second excitation electrode 112) is formed on both main surfaces 101 and 102 of the crystal resonator element 10. The crystal resonator plate 10 includes a vibration portion 11 configured to be substantially rectangular, an outer frame 12 surrounding an outer periphery of the vibration portion 11, and a holding portion 13 holding the vibration portion 11 by coupling the vibration portion 11 to the outer frame 12. That is, the crystal resonator plate 10 has a structure in which the vibrating portion 11, the outer frame portion 12, and the holding portion 13 are integrally formed. The holding portion 13 extends (protrudes) in the-Z 'direction to the outer frame portion 12 from only one corner portion located in the + X direction and the-Z' direction of the vibrating portion 11.

The first excitation electrode 111 is provided on the first main surface 101 side of the vibrating portion 11, and the second excitation electrode 112 is provided on the second main surface 102 side of the vibrating portion 11. Lead wirings (a first lead wiring 113 and a second lead wiring 114) for connecting the excitation electrodes to external electrode terminals are connected to the first excitation electrode 111 and the second excitation electrode 112. The first lead-out wiring 113 is led out from the first excitation electrode 111, and is connected to the connection bonding pattern 14 formed on the outer frame portion 12 via the holding portion 13. The second lead wiring 114 is led from the second excitation electrode 112, and is connected to the connection bonding pattern 15 formed on the outer frame portion 12 via the holding portion 13.

On both main surfaces (the first main surface 101 and the second main surface 102) of the crystal resonator plate 10, vibration-side sealing portions for bonding the crystal resonator plate 10 to the first sealing member 20 and the second sealing member 30 are provided, respectively. A vibration-side first bonding pattern 121 is formed as a vibration-side seal portion of the first main surface 101; a vibration-side second bonding pattern 122 is formed as a vibration-side seal portion of the second main surface 102. The vibration side first bonding pattern 121 and the vibration side second bonding pattern 122 are provided on the outer frame portion 12, and are formed in a ring shape in a plan view.

As shown in fig. 4 and 5, the crystal resonator plate 10 has five through holes penetrating between the first main surface 101 and the second main surface 102. Specifically, the four first through holes 161 are provided in regions at four corners (corners) of the outer frame portion 12. The second through-hole 162 is provided on one side of the vibrating portion 11 in the Z 'axis direction (the side in the-Z' direction in fig. 4 and 5) in the outer frame portion 12. Connection bonding patterns 123 are formed around the first through holes 161. In addition, around the second through-hole 162, the connection bonding pattern 124 is formed on the first principal surface 101 side; the second main surface 102 has a connecting bonding pattern 15 formed thereon.

Of the first through-hole 161 and the second through-hole 162, through-electrodes for achieving electrical conduction between the electrode formed on the first main surface 101 and the electrode formed on the second main surface 102 are formed along the inner wall surfaces of the through-holes. Further, the central portions of the first through-hole 161 and the second through-hole 162 are hollow portions that penetrate between the first main surface 101 and the second main surface 102.

As shown in fig. 2 and 3, the first sealing member 20 is a rectangular parallelepiped substrate made of 1 AT-cut quartz crystal piece, and the second main surface 202 (the surface bonded to the crystal resonator plate 10) of the first sealing member 20 is processed (mirror-finished) into a flat and smooth surface. Further, the first sealing member 20 is not a member having a vibrating portion, but by using an AT-cut quartz crystal piece as the crystal resonator plate 10, the crystal resonator plate 10 and the first sealing member 20 can have the same thermal expansion coefficient, and thermal deformation of the crystal oscillator 100 can be suppressed. The directions of the X axis, the Y axis, and the Z' axis of the first sealing member 20 are also the same as those of the crystal resonator plate 10.

As shown in fig. 2, six electrode patterns 22 including mounting pads for mounting the IC chip 40 as an oscillation circuit element are formed on the first main surface 201 (surface on which the IC chip 40 is mounted) of the first sealing member 20. The IC Chip 40 is bonded to the electrode pattern 22 by a metal bump (e.g., Au bump) 23 (see fig. 1) by a Flip Chip Bonding (FCB) method.

As shown in fig. 2 and 3, the first sealing member 20 is formed with six through holes which are connected to the six electrode patterns 22, respectively, and which penetrate between the first main surface 201 and the second main surface 202. Specifically, four third through-holes 211 are provided in regions at four corners (corners) of the first sealing member 20. The fourth through-hole 212 and the fifth through-hole 213 are provided in the + Z 'direction in fig. 2 and the-Z' direction in fig. 3, respectively.

Through-electrodes for electrically connecting the electrode formed on the first main surface 201 and the electrode formed on the second main surface 202 are formed along the inner wall surfaces of the third through-hole 211, the fourth through-hole 212, and the fifth through-hole 213, respectively. Further, the center portions of the third through-hole 211, the fourth through-hole 212, and the fifth through-hole 213 are hollow portions that penetrate between the first main surface 201 and the second main surface 202.

A sealing side first bonding pattern 24 as a sealing side first sealing portion for bonding to the crystal resonator plate 10 is formed on the second main surface 202 of the first sealing member 20. The sealing-side first bonding pattern 24 is formed in a ring shape in a plan view.

In addition, on the second main surface 202 of the first sealing member 20, the connection bonding pattern 25 is formed around the third through-hole 211, the connection bonding pattern 261 is formed around the fourth through-hole 212, and the connection bonding pattern 262 is formed around the fifth through-hole 213. Further, a connection bonding pattern 263 is formed on the opposite side of the connection bonding pattern 261 in the longitudinal direction of the first sealing member 20, and the connection bonding pattern 261 and the connection bonding pattern 263 are connected by a wiring pattern 27.

As shown in fig. 6 and 7, the second sealing member 30 is a rectangular parallelepiped substrate made of one AT-cut quartz crystal piece, and the first main surface 301 (the surface bonded to the crystal resonator plate 10) of the second sealing member 30 is processed (mirror-finished) into a flat and smooth surface. Further, it is preferable that the second sealing member 30 is also an AT-cut quartz crystal piece as the crystal resonator plate 10, and the directions of the X axis, the Y axis and the Z' axis are also the same as those of the crystal resonator plate 10.

A sealing side second bonding pattern 31 as a sealing side second sealing portion for bonding to the crystal resonator plate 10 is formed on the first main surface 301 of the second sealing member 30. The sealing-side second bonding pattern 31 is formed in a ring shape in a plan view.

On the second main surface 302 (the main surface not facing the outside of the crystal resonator plate 10) of the second sealing member 30, four external electrode terminals 32 electrically connected to the outside are provided. The external electrode terminals 32 are located at four corners (corners) of the second sealing member 30, respectively.

As shown in fig. 6 and 7, the second sealing member 30 is formed with four through holes penetrating between the first main surface 301 and the second main surface 302. Specifically, the four sixth through-holes 33 are provided in regions at four corners (corners) of the second sealing member 30. In the sixth through-hole 33, a through-electrode for conducting the electrode formed on the first main surface 301 and the electrode formed on the second main surface 302 is formed along the inner wall surface thereof. In addition, the center portion of each of the sixth through holes 33 is a through portion in a hollow state that penetrates between the first main surface 301 and the second main surface 302. Further, in the first main surface 301 of the second sealing member 30, connection bonding patterns 34 are formed around the sixth through holes 33, respectively.

In the crystal oscillator 100 including the above-described crystal resonator element 10, the first sealing member 20, and the second sealing member 30, the crystal resonator element 10 and the first sealing member 20 are diffusion bonded in a state where the vibration-side first bonding pattern 121 and the sealing-side first bonding pattern 24 are overlapped; the crystal resonator plate 10 and the second sealing member 30 are diffusion bonded in a state where the vibration-side second bonding pattern 122 and the sealing-side second bonding pattern 31 are overlapped, thereby forming a package having a sandwich structure as shown in fig. 1. Thereby, the inner space of the package, i.e., the accommodating space of the vibrating portion 11 is hermetically sealed.

In this case, the connection bonding patterns are also diffusion bonded in a state of being overlapped with each other. Further, the first excitation electrode 111, the second excitation electrode 112, the IC chip 40, and the external electrode terminal 32 are electrically connected to each other in the crystal oscillator 100 due to the bonding of the bonding patterns for connection.

Specifically, the first excitation electrode 111 is connected to the IC chip 40 via the first lead line 113, the wiring pattern 27, the fourth through-hole 212, and the electrode pattern 22 in this order. The second excitation electrode 112 is connected to the IC chip 40 through the second lead wiring 114, the second through hole 162, the fifth through hole 213, and the electrode pattern 22 in this order. The IC chip 40 is connected to the external electrode terminal 32 through the electrode pattern 22, the third through-hole 211, the first through-hole 161, and the sixth through-hole 33 in this order.

In the crystal oscillator 100, each bonding pattern is preferably formed by laminating a plurality of layers on a quartz crystal wafer, and a Ti (titanium) layer and an Au (gold) layer are preferably formed by vapor deposition from the lowermost layer side thereof. In addition, it is preferable that other wirings and electrodes formed on the crystal oscillator 100 have the same structure as the bonding pattern, so that the bonding pattern, the wirings, and the electrodes can be patterned at the same time.

The above is the basic configuration of the crystal oscillator 100 according to the first embodiment, but the present invention is characterized in that the through-hole has a shape capable of preventing the occurrence of cracks by alleviating stress concentration. Hereinafter, this feature will be described in detail.

In the manufacturing process of the crystal oscillator 100, the crystal resonator element 10, the first sealing member 20, and the second sealing member 30 are bonded to obtain a package having a sandwich structure, and then the IC chip 40 is mounted near the center of the first main surface 201 of the first sealing member 20. As described with reference to fig. 13, an external force is applied to the first sealing member 20 from above during mounting of the IC chip 40, and the stress generated in the first sealing member 20 is a factor of generating cracks in the through-hole due to the external force.

The piezoelectric resonator device to which the present invention is applied is not limited to the crystal oscillator as in the above example, and may be a crystal resonator including only a package of a crystal resonator plate, a first sealing member, and a second sealing member. That is, even in a crystal resonator in which an IC chip is not mounted, there are cases where a wiring for routing or a shield electrode is formed on the first main surface (the surface on the side not bonded to the crystal resonator plate) of the first sealing member, and there are cases where a through-hole for conducting the wiring or the electrode is provided in the first sealing member. In addition, even if the IC chip is not mounted on the first sealing member, an external force may be applied to the first sealing member in the operation process of the crystal resonator. Therefore, a technical problem may occur in the crystal resonator, in which stress concentration in the through-hole of the first sealing member becomes a factor of generation of cracks.

In the crystal oscillator 100, stress concentration in the through hole is likely to occur particularly in the fourth through hole 212. The reason for this will be explained first.

When the through-hole formed in the piezoelectric resonator device is formed in a polygonal shape in a plan view, a corner portion of the polygonal shape may become a stress concentration point and may become a starting point of crack generation, and therefore, the through-hole is generally formed in a circular shape without corners. The through-hole in the piezoelectric vibration device is formed by wet etching, whereas a mask used in conventional etching is circular.

However, when a through-hole is formed in a quartz crystal wafer, even when a circular mask is used, the through-hole cannot be formed in a complete circular shape due to the crystal anisotropy of the quartz crystal. Fig. 8(a) is a cross-sectional view showing a shape of a through hole in a case where the through hole is formed by etching using a circular mask on an AT-cut quartz crystal wafer, and fig. 8(b) is a plan view showing a shape of the through hole in a case where the through hole is formed by etching using a circular mask on an AT-cut quartz crystal wafer.

As shown in fig. 8(a), the through-hole has a through-hole 71 near the center in the in-plane direction, and an inclined surface 72 inclined from the peripheral portion of the through-hole toward the through-hole 71 at the center. In addition, since the through-holes are formed by etching from both main surfaces of the AT-cut quartz crystal piece 70, the inclined surfaces 72 are formed on both main surface sides of the AT-cut quartz crystal piece 70.

When the through-hole is viewed in a direction perpendicular to the main surface of the AT-cut quartz crystal wafer 70, the through-hole is not completely circular, and the inclined surface 72 is also composed of a combination of a plurality of crystal planes, as shown in fig. 8 (b). The inclined surface 72 has a first crystal plane S1, a second crystal plane S2, and a third crystal plane S3, wherein the first crystal plane S1 extends from the through hole 71 toward the peripheral portion of the through hole in the-Z' direction and the + X direction; the second crystal plane S2 extends from the through hole 71 toward the peripheral portion of the through-hole toward the-Z 'direction side and the + X direction side, and contacts the first crystal plane S1 on the + Z' direction side and the + X direction side of the first crystal plane S1; the third crystal plane S3 is in contact with the second crystal plane S2 on the + X direction side of the second crystal plane S2, and is in contact with the main surface of the AT-cut quartz crystal piece 70 (in contact with the outer peripheral edge portion of the through-hole).

In the through-hole, a first ridge line L1 between the first crystal plane S1 and the second crystal plane S2 and a second ridge line L2 between the second crystal plane S2 and the third crystal plane S3 intersect AT a point Pc on the outer peripheral edge portion of the through-hole (i.e., the boundary line between the inclined surface 72 and the main surface of the AT-cut quartz crystal piece 70).

In the first sealing member 20 of the crystal oscillator 100, the third through hole 211 to the fifth through hole 213 are configured as through holes shown in fig. 8(a) and 8(b), and when an external force is applied to the first sealing member 20 from above, stress generated in the first sealing member 20 by the external force acts on each through hole. At this time, the point Pc in the through-hole becomes a stress concentration point, and easily becomes a starting point of the crack generation due to the stress. In the fourth through-hole 212 located on the + Z' -direction side with respect to the inner peripheral edge portion of the outer frame portion 12 of the crystal resonator plate 10, when the point Pc serves as an action point of the lever principle, the distance between the point Pc and the fulcrum (the inner peripheral edge portion of the outer frame portion 12 of the crystal resonator plate 10) is shorter than those of the other through-holes, and cracks are particularly likely to occur.

Next, the shape of the through-hole according to the first embodiment, which can prevent the occurrence of such cracks, will be described with reference to fig. 9(a) and 9 (b). The through-hole according to the first embodiment is characterized in that the compensation surface Sc is formed on the outer peripheral edge portion of the through-hole (the boundary line between the inclined surface 72 and the main surface of the AT-cut quartz crystal piece 70) so that the point Pc which becomes the stress concentration point does not appear on the outer peripheral edge portion of the through-hole. Fig. 9(a) is an enlarged plan view of the vicinity of the compensation surface Sc of the through-hole, and fig. 9(b) is an enlarged perspective view of the vicinity of the compensation surface Sc of the through-hole as viewed obliquely from above.

As shown in fig. 9(a) and 9(b), the through-hole according to the first embodiment has a compensation surface Sc formed therein, which is in contact with the outer peripheral edge of the through-hole. Further, the compensation surfaces Sc are formed near the outer peripheral edge portions of the through-holes in the-Z' direction and the + X direction, and therefore, the compensation surfaces Sc can prevent the first ridge line L1 and the second ridge line L2 from reaching the main surface of the AT-cut quartz crystal piece 70.

As described above, in the through-hole according to the first embodiment, since the offset surface Sc is formed, the first ridge line L1 and the second ridge line L2 cannot intersect AT the outer peripheral edge portion of the through-hole (the boundary line between the inclined surface 72 and the main surface of the AT-cut quartz crystal piece 70). As a result, the point Pc (i.e., stress concentration point) shown in fig. 8 b can be prevented from being generated, and the crack starting from the point Pc can be prevented from being generated.

The through-hole according to the first embodiment can be realized by processing the shape of the mask when the through-hole is formed by etching. As described above, when the circular mask is used, a point Pc which becomes a stress concentration point is generated in the through hole as shown in fig. 8 (b). In contrast, in the production of the through-hole according to the first embodiment, the mask 80 shown in fig. 10 is used. The mask 80 is a mask in which a swelling portion 81 swelling to the inner peripheral side is provided in a part of a circular mask. The formation position of the bulging portion 81 corresponds to the generation position of the point Pc, that is, the outer peripheral edge portions in the-Z' direction and the + X direction in the through-hole. When a through-hole is formed by etching using such a mask 80, the compensation surface Sc is formed in a portion of the formed through-hole corresponding to the expanded portion 81.

Here, the shape and size of the expanded portion 81 on the mask 80 are not particularly limited. That is, although the shape and size of the compensation surface Sc vary depending on the shape and size of the expanded portion 81, the most important component of the compensation surface Sc is the formation site thereof (a site that can prevent the first ridge line L1 and the second ridge line L2 from reaching the main surface of the AT-cut quartz crystal piece 70).

However, it is considered that when the compensation surface Sc is too small, the compensation effect is small, and the effect of sufficiently suppressing the stress concentration in the through-hole cannot be obtained. Conversely, if the offset surface Sc is too large, the shape of the inclined surface 72 of the through-hole may be complicated by the offset surface Sc, and the on-resistance of the through-electrode formed in the through-hole may be increased. Therefore, the compensation surface Sc is preferably formed to have an appropriate size, and specifically, as shown in fig. 9(b), the compensation surface Sc is preferably formed to be in contact with only the first to third crystal planes S1 to S3 and not in contact with the other crystal planes.

As shown in fig. 11, when the two end points of the boundary line between the compensation plane Sc and the main surface of the AT-cut quartz crystal piece 70 are Pc1 and Pc2, the distance W1 between the two points of Pc1 and Pc2 is preferably in the range of 5% to 30% of the maximum diameter D1 of the through-hole. The maximum diameter D1 of the through-hole is the maximum distance among the distances between two arbitrary points present on the outer periphery of the through-hole.

The structure of the through-hole (the through-hole having the compensation surface Sc) according to the first embodiment described above is not necessarily applied to all the through-holes included in the piezoelectric resonator device, and basically, only needs to be applied to the through-hole in which a crack is generated when a conventional shape is adopted. For example, in the crystal oscillator 100 shown in fig. 1 to 7, at least the fourth through-hole 212 formed in the first sealing member 20 and located on the + Z' -direction side with respect to the inner peripheral edge portion of the outer frame portion 12 of the crystal resonator plate 10 may have a through-hole structure according to the first embodiment. In the fourth through-hole 212, only the surface not bonded to the crystal resonator plate 10, that is, the first main surface 201, which is likely to be cracked, and the second main surface 202 bonded to the crystal resonator plate 10 are unlikely to be cracked. Therefore, the compensation surface Sc may be formed only on the first main surface 201 side of the first seal member 20 in the through-hole.

< second embodiment >

Hereinafter, a second embodiment of the present invention will be described in detail with reference to the drawings. The basic structure of the piezoelectric resonator device according to the second embodiment is the same as that of the crystal oscillator 100 described with reference to fig. 1 to 7. In the second embodiment, a description will be given of a shape of a through-hole capable of preventing occurrence of cracks, using an example different from the first embodiment.

First, the shape of the through-hole according to the second embodiment will be described with reference to fig. 12(a) and 12 (b). Fig. 12(a) is a plan view of the through-hole according to the second embodiment, and fig. 12(b) is a cross-sectional view taken along line a-a in fig. 12 (a). Here, fig. 12(b) shows a cross section from the middle to one main surface in the thickness direction of the through-hole.

As shown in fig. 12(a) and 12(b), in the through-hole according to the second embodiment, a step portion 73 is formed on the outer peripheral side of the through-hole so that a point Pc, which becomes a stress concentration point, does not occur on the outer peripheral edge portion of the through-hole. That is, in the through-hole according to the second embodiment, the inclined surface 72 is formed around the through-hole 71, and the stepped portion 73 is formed on the outer peripheral side of the inclined surface 72.

In the through-hole according to the second embodiment, since the stepped portion 73 is formed on the outer peripheral side of the through-hole, the point Pc AT which the first ridge line L1 and the second ridge line L2 intersect does not exist on the outer peripheral edge of the through-hole (the boundary line between the stepped portion 73 and the main surface of the AT-cut quartz crystal piece 70). In other words, by providing the step portion 73, the intersection of the first ridge line L1 and the second ridge line L2 can be blocked by the step portion 73, and thus it can be avoided that it reaches the main surface of the AT-cut quartz crystal piece 70. As a result, the stress concentration point can be prevented from being generated on the outer peripheral edge portion of the through-hole, and the crack starting from the stress concentration point can be prevented from being generated.

The through-hole according to the second embodiment can be formed by etching in two stages when the through-hole is formed by etching. Specifically, in the first etching, as shown in fig. 13(a), etching is performed from both main surfaces of the AT-cut quartz crystal piece 70 until the through hole 71 is formed. Then, in the second etching, it is preferable to form a step portion 73 by penetrating the through hole 71 as shown in fig. 13 (b).

In the first etching, circular masks of the same size are used for both main surfaces. In the second etching, the mask for forming the main surface of the stepped portion 73 is replaced with a new mask having a larger size. That is, the circular mask used in the first etching is peeled off from the AT-cut quartz crystal wafer 70, and then a new mask is formed. As will be described in detail later, in the through-hole according to the second embodiment, it is basically not necessary to provide the step portions 73 on both principal surfaces of the AT-cut quartz crystal piece 70. Therefore, in the cross section shown in fig. 13(b), the stepped portion 73 is provided only on the upper main surface side, and the stepped portion 73 is not provided on the lower main surface side. In the main surface where the stepped portion 73 is not provided, the mask does not need to be changed between the first etching and the second etching.

In the second etching for forming the step portion 73, the shape of the mask used may be circular or may not be circular. In the case of using a circular mask in the second etching, the size (diameter) of the mask is larger than that of the circular mask used in the first etching. In the second etching, the mask may be arranged concentrically with the mask in the first etching, or may be eccentric with respect to the mask in the first etching. That is, the mask in the second etching may be arranged to be eccentric to the-Z' direction and/or the + X direction side than the mask in the first etching so as to ensure that the stepped portion 73 is formed at a position corresponding to the generation portion of the point Pc.

In addition, even in the case where a mask other than the circular shape is used for the second etching, it is preferable to treat the shape so as to ensure that the stepped portion 73 is formed at a position corresponding to the generation portion of the point Pc. For example, as shown in fig. 14(a) and 14(b), the mask 83 used in the second etching may have an expanded portion 83A whose outer peripheral edge is expanded in the-Z' direction and/or the + X direction with respect to the circular mask 82 used in the first etching.

Here, the shape and size of the expanded portion 83A of the mask 83 are not particularly limited. That is, although the shape and size of the stepped portion 73 vary depending on the shape and size of the extension portion 83A, the shape and size of the extension portion 83A are not particularly limited since the most important point of the stepped portion 73 is the stop point Pc formed on the outer peripheral edge of the through-hole. The stepped portion 73 need not be formed over the entire circumference of the through-hole, but may be formed at least in the regions from the through-hole 71 to the-Z' direction side and the + X direction side.

However, it is considered that, when the stepped portion 73 in the vicinity of the generation portion of the point Pc is too small, the point Pc which becomes a stress concentration portion is generated at a portion close to the outer peripheral edge of the through-hole, and therefore, an effect of sufficiently suppressing the stress concentration in the through-hole cannot be obtained. Conversely, if the stepped portion 73 is too large, a new stress concentration point may be generated AT the outer peripheral edge of the stepped portion 73 (i.e., the boundary line between the stepped portion 73 and the main surface of the AT-cut quartz crystal piece 70) and may become a starting point of crack generation. Therefore, the stepped portion 73 is preferably formed to have an appropriate size. From this viewpoint, for example, it is preferable that the depth (depth in the thickness direction) of the stepped portion 73 is set to be 5 μm to 20 μm. Alternatively, the maximum distance between the inner and outer peripheral edges of the stepped portion 73 (the distance in the vicinity of the point Pc where the point Pc is generated) is preferably 5 μm to 20 μm.

The through-hole (through-hole having the stepped portion 73) according to the second embodiment described above is not necessarily applied to all through-holes included in the piezoelectric vibration device, and basically, may be applied to a through-hole in which a crack is generated when a conventional shape is adopted. For example, in the crystal oscillator 100 shown in fig. 1 to 7, at least the fourth through-hole 212 formed in the first sealing member 20 and located on the + Z' -direction side with respect to the inner peripheral edge portion of the outer frame portion 12 of the crystal resonator plate 10 may be formed as the through-hole according to the second embodiment. Also, the fourth through-hole 212 is a surface that is not bonded to the crystal resonator plate 10, that is, the first main surface 201, and is also likely to be cracked, and cracks are not likely to be generated from the second main surface 202 bonded to the crystal resonator plate 10. Therefore, the stepped portion 73 may be formed only on the first main surface 201 side of the first seal member 20 in the through-hole.

The embodiments disclosed above are illustrative of various aspects of the present invention and are not to be construed as limiting. That is, the technical scope of the present invention is defined by the description of the claims, and cannot be interpreted only by the embodiments described above. The present invention includes all modifications within the meaning and range equivalent to the claims.

< description of reference numerals >

100 crystal oscillator (piezoelectric vibrating device)

10 crystal vibrating reed (piezoelectric vibrating reed)

11 vibration part

111 first excitation electrode

112 second excitation electrode

12 outer frame part

13 holding part

20 first sealing member

201 (of the first sealing member) a first main face

202 (of the first sealing member) second main face

211 third through hole (through hole of first seal member)

212 fourth through hole (through hole of first sealing member)

213 fifth through hole (through hole of first sealing member)

30 second seal member

40 IC chip

70 AT cut quartz crystal wafer

71 through hole

72 inclined plane

73 step part

80 mask

81 bulging part

82 mask used in the first etching

83 mask used in the second etching

83A expansion part

S1 first crystal plane

S2 second crystal plane

S3 third junction plane

L1 first ridge

L2 second ridge.