JP2002009578A - Piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric device that is not susceptible to an electric effect in the case of the frequency adjustment so as to enhance the frequency adjustment accuracy and the frequency adjustment speed and maintains high performance without reception of at least a downward electric effect. SOLUTION: A cover 34 is fixed to a package 33 to form a prescribed internal space 33a on the inside and a piezoelectric vibration chip 32 is contained in the internal space in this piezoelectric device. The package 33 is provided with a ground electrode film 48 placed lower than a part at which the piezoelectric vibrator chip is contained and located.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a piezoelectric device in which a piezoelectric vibrating reed is accommodated in a package having a base with a lid.

[0002]

2. Description of the Related Art FIGS. 16 and 17 show a general piezoelectric vibrator as a piezoelectric device in which a piezoelectric vibrating piece is sealed in a base of a package. FIG. FIG. 17 is a plan view and FIG. 17 is a sectional view taken along line AA.

In these figures, a piezoelectric vibrator 1 has a box-shaped base 3 in which a space 3a for accommodating a plate-shaped piezoelectric vibrating piece 2 is formed, and a base 3 which seals the space 3a.
Cover 4 made of metal such as Kovar joined to
It has. In this case, the base 3 and the lid 4 form a package.

[0006] As shown in FIG. 16, the package is provided with drive electrodes 14 e and 14 f for connection to the outside, and one end 2 a of the piezoelectric vibrating reed 2 has a space 3
a is connected and fixed via the conductive adhesive 5a to the drive electrodes 14e and 14f exposed in the
b is a free end. An excitation electrode 7 and the like are provided on the surface of the piezoelectric vibrating reed 2 and are connected to the drive electrodes 14e and 14f.

[0005] With this, it is possible to vibrate at a predetermined frequency by the drive voltage applied from the electrode 5.

[0006] Here, the above-mentioned base 3 is, for example, shown in FIG.
It is configured as shown in FIG.

That is, the base 3 is formed by stacking three layers of ceramic bodies each having a predetermined shape.

[0008] The first layer located at the bottom of the layer structure of the base 3
The layer 13 has a rectangular thin plate shape as shown in FIG. FIG. 18E shows the first layer 1.
In order to show the electrode structure on the back surface of No. 3, above the back surface,
It is shown in a transparent state.

In FIG. 1, a pair of drive electrode terminals 13e and 13f and a pair of drive electrode terminals 1
Conductive patterns extending from 3e and 13f are provided, and the conductive patterns are routed to end face electrodes 13b and 13d of the first layer 13 at diagonal positions to each other. And
Diagonal ends different from these are provided with end face electrodes 13a, 13a.
c is formed.

On the back surface of the first layer 13, FIG.
Drive electrode terminals 13g and 13h connected to the end face electrodes 13b and 13d of (e) are formed. Further, a ground terminal 13 is provided on another pair of diagonally upper corners.
i, 13j are formed, connected to the end face electrodes 13a, 13c, and sequentially electrically connected to end face terminals that are superimposed thereon as described later.

On this first layer 13, a second layer 14 shown in FIG. The second layer 14 has a rectangular frame shape, has an inner diameter inside corresponding to the internal space 3a in FIG. 17, and has two island-shaped steps 14k, 141 are provided. On each of the step portions 14k and 14l, a through hole penetrating vertically and drive electrodes 14e and 14f formed on the inner surface of the through hole are provided.
Are stacked on the first layer 13, these drive electrodes 14
e, 14f are the drive electrodes 13e, 13f on the surface of the first layer.
It is designed to be electrically conductive.

End electrodes 14a, 14b, 14c and 14d are formed at the four corners of the second layer 14, respectively, and the inside of the end electrodes 14a and 14c is vertically penetrated. Electrodes 14g and 14h are provided, and are electrically connected to the adjacent end face electrodes 14a and 14c, respectively.

A third layer 15 shown in FIG. 18B is disposed on the second layer 14. The third layer 15 is the second layer 1
4, and has a pair of vertically penetrating through holes formed at diagonal positions with respect to each other, and an electrode which is electrically connected to a ground terminal is formed on the inner surface of the through hole.

Further, on the third layer 15, FIG.
The seam ring 16 shown in FIG. This seam ring 16 is located at the upper end of the third layer 15 and
It is fixed to the side or the lower surface of the lid 4 in FIG. 17 and is used for seam welding at the time of sealing.

The base 3 is configured as described above.
The driving voltage supplied from the outside is supplied to the driving electrode terminals 13 g and 13 h on the back surface of the first layer 13,
Through b and 13d, they are supplied to the drive electrodes 13e and 13f through the front side conductive pattern. The drive voltage is applied from the drive electrodes 13e and 13f to the drive electrodes 14e and 14f via the drive electrodes 14e and 14f formed on the step portion of the second layer 14 as described with reference to FIG. When applied to the excitation electrode 7 of the piezoelectric vibrating reed 2, the piezoelectric vibrating reed 2 vibrates at a predetermined frequency.

FIGS. 19 and 20 show a piezoelectric vibrator 20 in which the lid is formed of a ceramic material.
9 is a schematic cross-sectional view of the piezoelectric vibrator 20, and FIG. 20 is a schematic plan view showing the internal configuration of the piezoelectric vibrator 20 with the lid removed.

In the figure, a piezoelectric vibrator 20 has a conductive adhesive 25c on one end 25a of a plate-like piezoelectric vibrating piece 25 formed on a drive electrode 28, 29 formed on the surface of a base 23 having a one-layer structure. The other end 25b is a free end. That is, the piezoelectric vibrating piece 25 is inclined so that the free end 25b faces slightly upward, so that a small space is formed below and the vibration performance can be exhibited. An excitation electrode 27 is provided on the surface of the piezoelectric vibrating reed 25, and the drive electrode 28,
29.

On the base 23, a lid 24 made of ceramic is sealed and joined by a sealing glass 26. The lid 24 is formed in a concave shape, and the piezoelectric vibrating reed 2
5 is formed therein.

Here, the base 23 is formed as shown in FIG.

FIG. 21 (a) is a plan view of the base 23, FIG. 21 (b) is a front view of the base 23, and FIG. 21 (c) is a bottom view of the base 23.

In the figure, a base 23 is a single plate made of ceramic, and a pair of drive electrodes 28 and 29 described above are formed on the surface thereof. The drive electrode 28
Electrode terminal 3 formed on one short side end face of base 23
1, and the drive electrode 29 is connected to an electrode terminal 32 formed on the other short side end face. Further, on the back side of the base 23, bottom electrode terminals 33, 34 connected to the respective electrode terminals 31, 32 are formed.

As a result, in the piezoelectric vibrator 20,
By applying a drive voltage to each of the electrode terminals 31, 32, 33, and 34, the piezoelectric vibrating reed 25 can be vibrated at a predetermined frequency.

[0023]

In the case of the above-described piezoelectric vibrator 1 having a metal lid, when the lid 4 is sealed, a current is applied to the lid and the seam ring 16. Joined by resistance welding.

The completed piezoelectric vibrator 1 has the metal lid 4 attached to the upper surface, so that the electrical influence from above can be shielded.

However, before the lid 4 is sealed, the excitation electrode 7 of the piezoelectric vibrating reed 2 is irradiated with, for example, an ion beam or the like in a state where the lid 4 is removed. In the performed frequency adjustment step, the inside of the base 3 is charged, which hinders high-speed frequency adjustment.

Further, in the case of the piezoelectric vibrator 20 having a ceramic lid, the piezoelectric vibrator 20 is affected by the stray capacitance in the frequency adjustment step, and the lid 24 is not made of metal. Since it is not possible to shield against environmental influences, there is a problem that it is difficult to use the product for which high performance is required.

The present invention solves the above-mentioned problems, and is not affected by an electric influence at the time of frequency adjustment. Therefore, the frequency adjustment accuracy and the frequency adjustment speed can be improved.
It is an object of the present invention to provide a piezoelectric device that can maintain high performance without being affected by at least electric power from below.

[0028]

According to the first aspect of the present invention, a lid is fixed to a base so as to form a predetermined internal space inside, and a piezoelectric vibration is applied to the internal space. This is achieved by a piezoelectric device that accommodates a piece, wherein the base includes a ground electrode film below a location where the piezoelectric vibrating piece is accommodated.

According to the first aspect of the present invention, the base accommodating the piezoelectric vibrating reed includes the ground electrode film below the piezoelectric vibrating reed.
When the frequency is adjusted by irradiating the piezoelectric vibrating reed with an electron beam, plasma, or the like from above, it is possible to prevent an electrical change inside the base from occurring.
Highly accurate frequency adjustment is possible.

Further, when mounted on a circuit board or the like, since there is no electrical influence from at least below the base of the circuit board or the like, the vibration performance is stabilized.

According to a second aspect of the present invention, in the configuration of the first aspect, the base has a plate-like lower layer for forming a bottom surface;
An upper layer that is stacked on the lower layer and has at least one layer having a ring-shaped inner diameter corresponding to the internal space, and the lid that covers the upper edge of the upper layer is a metal lid. And a ground electrode film is formed on a surface of the lower layer exposed to the internal space, and a ground terminal is provided on an exposed lower surface of the lower layer.

According to the configuration of the second aspect, the ground electrode film is exposed on the upper surface of the lower layer, that is, on the surface below the piezoelectric vibrating reed of the base.

Therefore, the electric influence from above the base is shielded by the metal lid, and the electric influence from below the base and the influence of the stray capacitance in the base are shielded by the ground electrode film. .

According to a third aspect of the present invention, in the configuration of the second aspect, the base is made of a ceramic material, and the lower layer has a lower first lower layer and a second lower layer superposed thereon. The ground electrode film is formed between a first lower layer and a second lower layer.

According to the structure of the third aspect, the lower layer of the base is divided to provide the first lower layer and the second lower layer, and the ground electrode film is formed therebetween. Since the lower layer is originally divided, the strength is improved by forming the ground electrode film therebetween without increasing the total thickness extremely. Also,
Since the ceramic material is a porous material, airtightness is improved by stacking a plurality of layers.

According to a fourth aspect of the present invention, in the configuration of the first aspect, the base is formed of a plate-shaped ceramic material, and the base is formed of a ceramic which forms the internal space inside. Is sealed and fixed, and the plate-shaped base has a lower first layer and a second layer superposed on the lower first layer. The ground electrode film is formed between the two layers, and a ground terminal is provided on an exposed lower surface of the first layer.

According to the fourth aspect of the present invention, even if it is divided into the first layer and the second layer, if the thickness of one layer is the same as the conventional one, the overall size of the product can be increased. In addition to the above, the strength is improved by forming a ground electrode film between them. Further, since the ceramic material is a porous material, airtightness is improved by stacking a plurality of layers.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the ground electrode film is formed at a position in the base corresponding to a position where the piezoelectric vibrating reed is arranged. It is characterized by.

According to the fifth aspect of the present invention, the ground electrode film is formed below the piezoelectric vibrating reed in the base at a position corresponding to the position where the piezoelectric vibrating reed is arranged. When applying a predetermined voltage to irradiate plasma from above the piezoelectric vibrating reed to adjust the frequency,
The etching rate can be significantly improved.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a piezoelectric vibrator according to a first embodiment of the present invention as a piezoelectric device in which a piezoelectric vibrating piece is sealed in a package. FIG. FIG. 1 is a schematic plan view, and FIG. 1 is a sectional view taken along the line BB. The piezoelectric vibrator 30 of this embodiment has the structure shown in FIGS.
This configuration is common to the conventional piezoelectric vibrator described in (1) except for the configuration of a ground electrode film described later. Here, the package refers to a configuration in which a lid is fixed to the base.

In these figures, the piezoelectric vibrator 30
A box-shaped base 33 in which a space 33a for accommodating the plate-shaped piezoelectric vibrating piece 32 is formed, and a plate-shaped lid 3 formed of metal joined to the base 33 so as to seal the space 33a.
4 is provided.

As a material of the piezoelectric vibrating reed 32, for example, an artificial quartz is used as a material exhibiting a piezoelectric action, and an excitation electrode 37 required for driving the piezoelectric vibrating reed 32 is formed on the surface thereof. I have.

As a material of the base 33, for example, a ceramic such as alumina is used. For example, the base 33 is laminated in a plurality of layers using a green sheet or the like as described later, and as shown in FIG. After being formed into a box shape, it is formed by firing.

The lid 34 is made of a material having conductivity and a coefficient close to the linear expansion coefficient of the base 33, and is formed of, for example, a flat plate made of metal or ceramic such as alumina. In the case of metal, for example, Kovar, 42
Alloy, stainless steel (SUS) and the like are preferable.

As shown in FIG. 2, the base 33 is provided with drive electrodes 44e and 44f for connection to the outside, and one end 32a of the piezoelectric vibrating reed 32 has a space 33a.
The drive electrodes 44e and 44f exposed inside are connected and fixed via a conductive adhesive 35a.
2b is a free end. The excitation electrode 37 is provided on the surface of the piezoelectric vibrating reed 32 as described above, and is connected to the drive electrodes 44e and 44f.

As a result, vibration can be made at a predetermined frequency by a driving voltage applied from the outside, as will be described later.

Here, the above-described base 33 is, for example,
It is configured as shown in FIGS.

That is, the base 33 is formed by stacking three layers of ceramic bodies each having a predetermined shape.

At the bottom of the layer structure of the base 33,
The first layer 43 constituting the lower layer has a rectangular thin plate shape as shown in FIG. Then, FIG.
FIG. 3 (c) is turned upside down to show the electrode structure on the back surface of the first layer 43.

In the figure, a pair of drive electrode terminals 43e and 43f and a conductive pattern extending from the drive electrode terminals 43e and 43f are provided on the surface side of the first layer 43. 43 are routed to end surface electrodes 43b and 43d at diagonal positions to each other. And
Diagonal ends different from these are provided with end face electrodes 43a, 43a.
c is formed.

Also, on the back side of the first layer 43, FIG.
Drive electrode terminals 43g and 43h connected to the end face electrodes 43b and 43d of (c) are formed, respectively. Furthermore, ground terminals 43i and 43j are formed at the other pair of diagonally upper corners, and the end face electrodes 43a and 43j are formed.
c. In this specification, “front side” means the lid side of the piezoelectric device, and “back side” means the bottom side of the piezoelectric device.

The present embodiment is different from the prior art in that the ground terminals 43i and 43j and the end face electrodes 43a and 43c are connected to the ground of the first layer 43 on the surface side shown in FIG. This is a point connected to the electrode film 48. The ground electrode film 48 is provided on the entire surface of the first layer 43 so as to be separated from the other drive electrode terminals 43e and 43f. Therefore, the piezoelectric vibrating reed 3 of FIG.
2 will be formed in the base 33 below.

Here, the ground electrode film 48 is formed, for example, by screen-printing a tungsten metallized layer.

On the first layer 43, a second layer 44 which is a part of the upper layer 49 constituting the base 33 of FIG. The second layer 44 has a rectangular frame shape or ring shape as shown in the plan view of FIG. 3B, and has an inner diameter inside corresponding to the internal space 33a of FIG. Inside one end are two island-shaped steps 4
4k, 44l are provided. Each step 44k, 4
4l, a through-hole penetrating vertically and drive electrodes 44 formed on the inner surface of the through-hole and the surface of the stepped portion.
e, 44f. When the first layer 43 is overlaid on the second layer 44, these drive electrodes 44
e, 44f are driving electrodes 43e, 43e on the surface side of the first layer 43.
43f.

End electrodes 44a, 44b, 44c, and 44d are formed at the four corners of the second layer 44, respectively. Of these, inside the end electrodes 44a and 44c, the third layer electrodes are provided. 44g and 44h for connection to the end face electrodes 44a and 44c, respectively.
It is conducting.

On this second layer 44, a third layer 45 forming a part of the upper layer 49 is arranged. As shown in FIG. 3A, the third layer 45 has substantially the same outer shape as the second layer 44, and has a pair of vertically penetrating through holes formed at diagonal positions to each other. Electrodes 45g and 45h are formed on the inner surface of the through hole. In addition, along the peripheral edge of the upper end of the third layer 45, a metal coating portion 45i made of a conductive metal is provided.
(Ground) is provided.

Further, the metal coating portion 45 of the third layer 45
Above i, the seam ring 46 shown in FIG. 1 is arranged. The seam ring 46 is provided on the metal coating portion 4 of the third layer 45.
5i, it is fixed to the base 33 side and used for seam welding at the time of sealing.

The piezoelectric vibrator 30 of the first embodiment is configured as described above, and operates as follows.

The externally supplied drive voltage is applied to the first layer 4
3 is supplied to the drive electrode terminals 43g and 43h on the rear surface, and is supplied to the drive electrodes 43e and 43f through the front surface side conductive patterns via the end surface electrodes 43b and 43d. The drive voltage is applied to the piezoelectric vibrating reed 3 from the drive electrodes 43e and 43f via the drive electrodes 44e and 44f formed on the step portion of the second layer 44.
The piezoelectric vibrating reed 32 is applied to the second excitation electrode 37 and vibrates at a predetermined frequency.

The piezoelectric vibrator 30 of the present embodiment is
The electrical influence from above is shielded by the metal lid 34. Then, as will be described in detail later, in a state where the lid 34 is removed, that is, in a state of FIG.
In frequency adjustment performed by irradiating the excitation electrode 37 of the piezoelectric vibrating reed 32 from above with, for example, plasma or the like, the ground electrode film 48 (see FIG. 4) exposed in the base 33 , Can be released via the ground terminals 43i and 43j on the back surface. For this reason, since there is no change in the electrical environment in the base 33, it is necessary to apply an electric voltage to the piezoelectric vibrating reed 32 while monitoring the vibration frequency thereof while electrically affecting the frequency adjustment. And accurate frequency adjustment can be performed.

Further, when the piezoelectric vibrator 30 of the present embodiment is mounted on a predetermined circuit board or the like, the electric influence from the board side can be shielded by the ground terminals 43i and 43j.

Thus, the piezoelectric vibrator 30 of the present embodiment
Is capable of accurate frequency adjustment, and even after mounting,
Alternatively, since accurate driving can be performed without being affected by electricity from below, the performance of a high-performance piezoelectric device that vibrates at a high vibration frequency can be extremely stably exhibited.

FIGS. 5 and 6 show a piezoelectric vibrator according to a second embodiment of the present invention as a piezoelectric device in which a piezoelectric vibrating reed is sealed in a package base. FIG. FIG. 5 is a schematic plan view with the exception of FIG.

In the piezoelectric vibrator 50 according to the second embodiment, the portions denoted by the same reference numerals as those in the first embodiment have the same configuration, and thus the duplicated description will be omitted, and the differences will be mainly described below. Will be described.

In this piezoelectric vibrator 50, the base 56 has a layer structure composed of a plurality of layers.
The second embodiment is different from the first embodiment in that a ground electrode film 58 is provided between the first lower layer 53 and the second lower layer 54 and is divided between the first lower layer 53 and the second lower layer 54. I have.

FIG. 8 shows each layer constituting the base 56 separately. FIG. 8E shows the first layer 5 which is the first lower layer.
8 shows the back surface side of FIG. 3 and FIG.
The surface side of the layer 53 is shown.

FIG. 8C shows the surface side of the second layer 54 as the second lower layer, and FIG. 8B shows the surface side of the third layer 44 which is the upper layer. (A) has shown the surface side of the 4th layer 45 which is an upper layer. Then, FIG.
The third layer 44 of FIG. 3B described in the first embodiment
The structure is the same as that of the second layer 44 of FIG.
Is the first layer 45 of FIG. 3A described in the first embodiment.
It has the same configuration as.

Therefore, only the difference between the first layer 53 and the second layer 54 will be described.

The first layer 53 and the second layer 54 have the function of separating the first layer 43 in the first embodiment into two layers, upper and lower. Therefore, the combined thickness of the first layer 53 and the second layer 54 is equal to the first layer 4 in the first embodiment.
3 is substantially equal to the thickness. That is, the thickness of the first layer 53 of the present embodiment is about 0.15 mm, the thickness of the second layer 54 is about 0.15 mm, and the thickness of the first layer 43 of the first embodiment is 0 mm. 0.2 mm or more.

On the back side of the first layer 53, drive electrode terminals 43g and 43h are formed, and end face electrodes 53b and 53d are formed.
Is connected to Further, ground terminals 43i and 43j are formed at the other pair of diagonal corners, and are connected to the end face electrodes 53a and 53c.

The present embodiment is different from the prior art in that the ground terminals 43i and 43j and the end face electrodes 53a and 53c are connected to the ground of the first layer 53 on the front side shown in FIG. This is a point connected to the electrode film 58. This ground electrode film 58 has the same configuration as the ground electrode film 48 of the first embodiment except that it is provided on the entire surface side of the first layer 53.

Then, on this first layer 53, FIG.
The second layer 54 shown in FIG. The surface side of the second layer 54 is exposed in the base 56. A pair of drive electrode terminals 43 is provided on the surface side of the second layer 54.
e, 43f, and a conductive pattern extending from the drive electrode terminals 43e, 43f.
End face electrodes 43b and 43 at diagonal positions of the second layer 54
d. End electrodes 43a and 43c are formed at diagonal ends different from these.

The end surface electrodes 43a, 43c of the second layer 54
Are connected to the ground electrode film 58 via the end surface electrodes 53a and 53c of the first layer 53 described above. And
The end surface electrodes 43b and 43d of the second layer 54 are the same as those of the first layer described above.
The driving electrode terminals 43g and 43h are connected via end electrodes 53b and 53d of the layer 53.

The drive electrode terminals 43e, 43e of the second layer 54
43f is connected to the drive electrodes 44e and 44f formed on the step portion of the third layer 44 as in the first embodiment, and the connection above this is the same as in the first embodiment.

Therefore, in the piezoelectric vibrator 50 according to the second embodiment, the ground electrode film 58 has the first layer 53 which is the first lower layer and the second layer 53 which is the second lower layer.
Since it is formed between the layers 54 over the entire surface, as shown in FIG.
Below, a ground electrode film 58 is provided.

Therefore, as in the first embodiment, the frequency of the piezoelectric vibrator 50 can be accurately adjusted, and the piezoelectric vibrator 50 can be accurately adjusted without being electrically affected from above or below even after mounting. Since the piezoelectric device can be driven, the performance of a high-performance piezoelectric device that vibrates at a high vibration frequency can be extremely stably exhibited.

In addition, the first layer 53 and the second layer 54 are both formed to be thin, and the two layers together have a thickness substantially equal to that of the first layer 43 of the first embodiment. Therefore, the device can be formed compact without being unnecessarily large.

Further, since the first layer 53 and the second layer 54 are both formed of a ceramic material, the ceramic is a porous body having a large number of fine holes. By thus separating the lower layer into two layers and stacking them, these fine holes in the first layer 53 and the second layer 54 are located at positions where they do not overlap with each other,
Since there is almost no risk of penetrating the two layers, the airtightness is improved.

Further, since the ground electrode film made of a conductive metal is formed between the first layer 53 and the second layer 54, the strength of the lower layer 55 is improved by the presence of the electrode film, and the same strength is obtained. In this case, the combined thickness of the first layer 53 and the second layer 54 can be made smaller than that of the first layer 43 of the first embodiment.

In the above embodiment, the ground electrode film 58 is formed on the front surface of the first layer 53, but may be formed on the back surface of the second layer 54 instead of the first layer 53. Of course.

FIG. 9 shows a piezoelectric vibrator according to a third embodiment of the present invention as a piezoelectric device in which a piezoelectric vibrating reed is sealed in a package. The piezoelectric vibrator has a lid made of a ceramic material. It is formed by.

In the piezoelectric vibrator 60 according to the third embodiment, the portions denoted by the same reference numerals as those in the first embodiment have the same configuration, and thus the duplicated description will be omitted, and the differences will be mainly described below. Will be described.

In the figure, a piezoelectric vibrator 60 is configured such that one end 32a of a plate-shaped piezoelectric vibrating piece 32 is formed with drive electrodes 68 and 69 formed on the surface of a base 63 formed of two layers as described later.
The upper end is connected and fixed with a slight inclination via a conductive adhesive 65c, and the other end 32b is a free end.
In other words, the piezoelectric vibrating reed 32 has a slight space formed below by inclining the free end 32b so as to face slightly upward, thereby exhibiting vibration performance. Excitation electrodes are provided on the surface of the piezoelectric vibrating reed 32 as in the first embodiment, and are connected to the driving electrodes 68 and 69.

On the base 63, a lid 64 made of ceramic is sealed and joined by, for example, a sealing glass 66 having a low melting point. The lid 64 is formed in a concave shape, and forms an internal space 62 a for accommodating the piezoelectric vibrating reed 32.

Here, the base 63 has a two-layer structure by overlapping and fixing a first layer 61 as a lower layer and a second layer 62 as an upper layer. Then, the first layer 61
The combined thickness of the second layer 62 and the second layer 62 has been described with reference to FIG.
The thickness is the same as that of the conventional single-layer package 23. That is, the first layer 61 of the present embodiment has a thickness of about 0.3 mm, and the second layer 62 has a thickness of about 0.3 mm.
The thickness is about 3 mm, and the thickness of the conventional base 23 is about 0.6 mm.

Next, the structure of each layer of the base 63 will be described.

FIG. 10 shows the structure of the second layer, which is the upper layer, and FIG.
(B) is a figure which shows the back surface side.

In the figure, the second layer 62 is formed of a substantially rectangular plate-like ceramic as shown in the figure, and the surface side is exposed to the surface side (inside) of the base 63. On the surface side of the second layer 62, a pair of drive electrode terminals 68, 69 and a conductive pattern extending from the drive electrode terminals 68, 69 are provided. This conductive pattern includes end face electrodes 71, diagonally opposite to each other on the second layer 62.
It is routed to 72. End electrodes 73 and 74 are formed at diagonal ends different from these.

As shown in FIG. 10B, a ground electrode film 75 is formed on the entire back surface of the second layer 62. The ground electrode film 75 is formed on the end face electrode 7.
3, 74 are connected.

FIG. 11 shows the back side of the first layer 61. On the back side of the first layer 61, drive electrode terminals 82 and 83 connected to the end face electrodes 71 and 72 in FIG.
9 is formed. Further, ground terminals 80 and 81 and end electrodes 76 and 77 are formed at the other pair of diagonal corners on the back surface side of the first layer 61. These end electrode terminals 76 and 77 are Second
The end face electrode terminals 73 and 74 of the layer 62 are connected to the ground electrode film 75.

The present embodiment is configured as described above. In this piezoelectric vibrator 60, similarly to the first embodiment, the frequency can be accurately adjusted, and even after mounting, the electric influence from below is obtained. Since the piezoelectric device can be driven accurately without receiving the vibration, the performance of a high-performance piezoelectric device that vibrates at a high vibration frequency can be extremely stably exhibited.

In addition to this, the first layer 61 and the second layer 62 are both formed to be thin and the thickness of the two layers is approximately equal to that of the conventional base 23. It can be formed compact without becoming unnecessarily large.

Furthermore, since both the first layer 61 and the second layer 62 are formed of a ceramic material, the ceramic is a porous body having a large number of fine holes. By thus separating the lower layer into two layers and overlapping them, these fine holes in the first layer 61 and the second layer 72 are located at positions where they do not overlap with each other,
Since there is almost no risk of penetrating the two layers, the airtightness is improved.

Further, since the ground electrode film made of a conductive metal is formed between the first layer 61 and the second layer 62, the strength of the base 63 is improved by the provision of the electrode film, and the same strength is obtained. In this case, the thickness can be made thinner than the conventional base 23.

In the above-described embodiment, the ground electrode film 75 is formed on the back surface of the second layer 62. However, the ground electrode film 75 may be formed on the front surface of the first layer 61 instead of the second layer 62. Of course.

FIG. 12 shows a first modification of the third embodiment. The configuration of the other parts is the same as that of the third embodiment except for the configuration of the second layer 89.

In the second layer 89, the ground electrode film 85
Has a plurality or a large number of holes 85a.

Thus, the second layer 6 is formed through the hole 85a.
2 by exposing the ceramic material on the back side of the first layer 61.
Can be brought into contact with the ceramic material on the upper surface of the substrate, so that the same material is joined to each other, and the strength at the time of lamination can be improved. Further, the electrode material can be saved by the amount corresponding to the formation of the holes 85a. Figure 1
Reference numeral 3 denotes a second modification of the third embodiment, and the second layer 9
Except for the configuration of 0, the configuration of other parts is the same as that of the third embodiment.

The ground electrode film 88 of the second layer 90 is
First ground electrode film 86 and second ground electrode film 87
And are separated into

The first ground electrode film 86 has substantially the same size and outer shape as the piezoelectric vibrating reed 32. In particular, in the state shown in FIG.
Is formed so as to be substantially similar to or the same shape as the piezoelectric vibrating reed 32. Then, the second ground electrode film 87 is formed around the first ground electrode film 86 so as to surround the first ground electrode film 86, so that only the ground electrode 86 is grounded during frequency adjustment, and argon ions are It is designed to efficiently collide with the excitation electrode. Thus, when used as a device, a sufficient shielding effect can be obtained by grounding the ground electrodes 86 and 87.

In the second modification, in particular, when the frequency is adjusted as shown in FIG. 14, only the piezoelectric vibrating reed 32 to be etched is selectively irradiated with plasma to reduce the etching rate. Can be increased.

FIG. 14 shows a frequency adjusting apparatus for executing the frequency adjusting method by the mass reduction method.

The frequency adjusting device 99 is provided in the vacuum chamber 9
1 and vacuum evacuation means 95 such as a vacuum pump for evacuating the vacuum chamber 91. Further, the vacuum chamber 91 is provided with an argon gas supply means 93 for supplying, for example, argon gas as an inert gas, and a cylindrical ion gun 92 containing, for example, an electrode rod therein. The rod has a high voltage source 94
Is connected.

The piezoelectric vibrating reed 32 to be subjected to reverse sputtering in frequency adjustment is mounted on the base 63 and has no lid joined thereto. For example, the piezoelectric vibrating reed 32 is opposed to the ion gun 92 by supporting means (not shown). Supported.

A drive voltage is applied to the excitation electrode 27 of the piezoelectric vibrating piece 32 from a drive voltage supply unit 97 via a control unit 96 having a monitoring unit. Can be monitored.

Further, the frequency adjusting device 99 includes voltage applying means 98 for applying a predetermined voltage to the ground electrode film 86 of the base 63 described above.

The frequency adjusting device 99 is configured as described above, and the air in the vacuum chamber 91 is supplied to the vacuum pump 9.
A predetermined amount of argon gas is introduced into the vacuum chamber 91 from the argon gas supply means 93 by evacuating to a predetermined degree of vacuum by 5.

In this state, the argon (Ar) gas filled in the vacuum chamber 91 is supplied to the ion gun 92.
It is turned into plasma and becomes positive ions. The argon ions, which have become positive ions, fly out from the tip of the ion gun 92 and hit the excitation electrode 27 of the opposing piezoelectric vibrating reed 32, and the metal particles of the metal film, which is the material forming the excitation electrode 27, recoil and fly out. , From being shaved,
The mass of the excitation electrode 27 is reduced. Thereby, the frequency of the vibration frequency f of the piezoelectric vibrating piece 32 is adjusted so as to gradually increase.

In this case, with respect to the ground electrode film 86,
When a negative voltage is applied by the voltage applying means 98, the ground electrode film 86 faces the ion gun 91 with the piezoelectric vibrating reed 32 interposed therebetween, so that argon ions fly toward the ground electrode film 86. . In this case, since the piezoelectric vibrating reed 32 is located in front of the ground electrode film 86, argon ions are selectively hit by using the piezoelectric vibrating reed 32 as a target.

FIGS. 15A and 15B show how the frequency is adjusted by the frequency adjusting device 99. FIG. 15A shows the frequency change of the piezoelectric vibrating reed 32, and FIG. Voltage to be applied.

As shown, during time T1,
With respect to the ground electrode film 86, the voltage applied by the voltage applying means 98 is relatively high in accordance with an instruction from the control means 96, and in this state, the etching speed is low. Next, for example, when the potential is increased to the negative side during the time T2,
The etching speed by argon ions increases,
Etched rapidly. Therefore, this corresponds to the coarse adjustment stage in the frequency adjustment. Further, during the time T3, if a potential slightly higher (changed to the plus side) than the potential at the time T2 is applied to the ground electrode film 86, the etching speed becomes slow.

As described above, the frequency is adjusted by the frequency adjusting device 99 using the piezoelectric vibrator of the present embodiment, so that the piezoelectric vibrating reed 32 can be selectively etched, and the etching speed can be reduced. It can be easily adjusted. As a result, the efficiency of frequency adjustment can be improved, and the frequency can be adjusted with high accuracy. Therefore, the frequency can be adjusted to a desired frequency f0 accurately, and a high-performance piezoelectric vibrator can be manufactured. .

The present invention is not limited to the above embodiment.
Each configuration of each of the above-described embodiments can be omitted or arbitrarily combined as appropriate.

The mounting structure and method of the present invention
The present invention is not limited to the above-described piezoelectric vibrator, but can be applied to any piezoelectric device using a piezoelectric oscillator or a piezoelectric vibrating piece in which a predetermined integrated circuit is incorporated.

[0116]

As described above, according to the present invention, since there is no electric influence at the time of frequency adjustment, the accuracy of frequency adjustment can be improved, and at least the electric influence from below is obtained. It is possible to provide a piezoelectric device that can maintain high performance without receiving the same.

Further, the piezoelectric device of the present invention is not affected by electric influence, and furthermore, the frequency adjustment speed of the vibration frequency can be easily controlled, so that the frequency can be adjusted more efficiently and with high precision. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a piezoelectric vibrator as a piezoelectric device according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of the piezoelectric vibrator of FIG. 1 with a lid removed.

3A and 3B show a configuration of a package of the piezoelectric vibrator of FIG. 1; FIG. 3A shows the surface of the third layer, FIG. 3B shows the surface of the second layer;
(C) is a diagram showing the front surface side of the first layer, and (d) is a diagram showing the back surface side of the first layer.

FIG. 4 is a plan view showing a state in which a lid and a piezoelectric vibrating piece of the piezoelectric vibrator of FIG. 1 are removed and a ground electrode film is exposed in a package;

FIG. 5 is a schematic sectional view showing an example of a piezoelectric vibrator as a piezoelectric device according to a second embodiment of the present invention.

FIG. 6 is a schematic plan view of the piezoelectric vibrator of FIG. 5 in a state where a lid is removed.

FIG. 7 is a schematic plan view of the piezoelectric vibrator of FIG. 5 with a lid and a piezoelectric vibrating reed removed.

8A and 8B show the configuration of the package of the piezoelectric vibrator shown in FIG. 5, wherein FIG. 8A shows the surface of the fourth layer, FIG.
(C) is the second layer surface side, (d) is the first layer surface side, (e)
FIG. 3 is a diagram illustrating a first layer rear surface side.

FIG. 9 is a schematic sectional view showing an example of a piezoelectric vibrator as a piezoelectric device according to a third embodiment of the present invention.

10A and 10B show the configuration of the package of the piezoelectric vibrator shown in FIG. 9; FIG. 10A is a diagram showing the front surface side of the second layer, and FIG.

FIG. 11 is a diagram showing a back surface side of a first layer in the configuration of the package of the piezoelectric vibrator of FIG. 9;

FIG. 12 shows a first configuration of the package of the piezoelectric vibrator of FIG.
The figure which shows the modification of FIG.

FIG. 13 shows a second configuration of the package of the piezoelectric vibrator of FIG.
The figure which shows the modification of FIG.

FIG. 14 is a schematic configuration diagram showing a frequency adjustment device for adjusting the frequency of the piezoelectric vibrating reed according to the embodiment of the present invention.

FIG. 15 is a graph showing a state of frequency adjustment by the frequency adjustment device of FIG. 14;

FIG. 16 is a schematic plan view of a piezoelectric vibrator as an example of a conventional piezoelectric device with a lid removed, as an example.

FIG. 17 is a schematic sectional view of a piezoelectric vibrator as the piezoelectric device of FIG.

18A and 18B show the configuration of the package of the piezoelectric vibrator of FIG. 17, wherein FIG. 18A shows a seam ring, FIG. 18B shows a third layer surface side, FIG. 18C shows a second layer surface side, and FIG. The first layer surface side,
(E) is a diagram showing the back side of the first layer.

FIG. 19 is a schematic sectional view showing another example of a piezoelectric vibrator as a conventional piezoelectric device.

FIG. 20 is a schematic plan view of the piezoelectric vibrator of FIG. 20 with a lid removed.

21A and 21B show a configuration of a base of the piezoelectric vibrator of FIG. 19, wherein FIG. 21A is a plan view of the base, FIG. 21B is a front view of the base, and FIG.

[Explanation of symbols]

 Reference Signs List 30 piezoelectric vibrator 50 piezoelectric vibrator 60 piezoelectric vibrator 32 piezoelectric vibrating piece 33 base 56 base 63 base 34 lid 48 ground electrode film 58 ground electrode film 75 ground electrode film 85 ground electrode film 88 ground electrode film

Claims (5)

[Claims] 1. A piezoelectric device in which a lid is fixed to a base so as to form a predetermined internal space inside, and a piezoelectric vibrating reed is accommodated in the internal space, wherein the base comprises: A ground electrode film is provided below a position where the piezoelectric vibrating reed is housed and arranged,
Piezo device. 2. The base has a plate-like lower layer for forming a bottom surface, and an upper layer which is overlaid on the lower layer and is at least one layer having a ring-shaped inner diameter corresponding to the internal space. Wherein the lid covering the upper edge of the upper layer is a metal lid, and a ground electrode film is formed on a surface of the lower layer exposed to the internal space, and a lower surface of the lower layer is exposed The piezoelectric device according to claim 1, further comprising a ground terminal. 3. The base made of a ceramic material, wherein the lower layer has a lower first lower layer and a second lower layer superposed thereon, wherein the ground is located between the first lower layer and the second lower layer. The piezoelectric device according to claim 2, wherein an electrode film is formed. 4. The base is formed of a plate-shaped ceramic material, and a ceramic lid forming the internal space is sealed and fixed to the plate-shaped base. The plate-shaped base has a lower first layer and a second layer superposed on the lower first layer, and the ground electrode film is formed between the first layer and the second layer. 2. The piezoelectric device according to claim 1, further comprising a ground terminal on an exposed lower surface of the first layer. 5. The piezoelectric device according to claim 1, wherein the ground electrode film is formed in the base at a position corresponding to a position where the piezoelectric vibrating reed is arranged. device.