JP3331574B2 - High frequency piezoelectric vibration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reference oscillation source for communication equipment,
Also, the present invention relates to a piezoelectric vibrating device such as a quartz oscillator or a quartz filter used as a clock source of a microcomputer, and particularly to a thin piezoelectric vibrating device adapted to a high frequency.

[0002]

2. Description of the Related Art As the frequency of communication equipment and the operating frequency of microcomputers increase, piezoelectric vibrating devices such as quartz oscillators and quartz filters are also required to support higher frequencies. In general, a thickness shear vibration of an AT-cut quartz plate is often used as a quartz plate corresponding to a higher frequency, and as is well known, the frequency is determined by the thickness, and the frequency and the thickness are inversely proportional. For example, 4.2
When trying to obtain a frequency of MHz, the thickness of the quartz plate is about 0.4 mm, but when trying to obtain a frequency of 20 MHz, the thickness of the quartz plate is about 0.08 mm. As the frequency increases, the thickness of the crystal plate decreases, and it becomes difficult to process the quartz plate itself such as cutting and polishing. In order to solve such a problem, the thickness of the quartz plate is the thickness of the fundamental wave, and in some cases, harmonic oscillation is used to obtain higher-order frequencies such as three times and five times. The required electrical characteristics may not be obtained depending on the applied electronic equipment, for example, the value (crystal impedance) becomes high, the peripheral circuit becomes complicated, and it is difficult to reduce the size as a whole.

To solve such a problem, FIG.
As shown in (1), there has been invented a configuration in which a concave portion is provided in the center portion of a quartz plate, a vibration region is formed in the concave portion, and the vibration region is reinforced by a thick portion around the thin region. FIG.
FIG. 9 is an internal cross-sectional view showing a conventional example, in which a thinned recess 9 is shown.
1 and a quartz plate 9 having a thick portion 92 formed therearound
In addition, the configuration is such that the excitation electrode 9a is drawn out from the concave portion to the end of the thick portion by the extraction electrode 9b. By adopting such a configuration, the vibration region can be made considerably thinner than in the past, and the frequency range of 40M, which is conventionally the region of the harmonic frequency,
The frequency of not less than Hz is realized by the fundamental vibration.

[0004]

However, in the above-described structure, it is difficult to form an electrode by vapor deposition or the like due to the presence of the concave portion. In particular, it is difficult to form an electrode material on the upright inner wall portion, and the thin-walled portion of the excitation electrode 9a Since the extraction electrode 9b extending to the thick portion passes through the sharp edge portion of the quartz plate, a part or all of the electrode may be cut at this portion, causing a conduction failure. In particular, a crystal oscillator having a higher frequency (that is, thinner) is required to make the electrode thinner than usual so as not to attenuate the excited vibration as much as possible. This was a factor that encouraged cutting.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a highly reliable piezoelectric vibrating device in which accidents such as electrode disconnection do not easily occur. Another object is to facilitate the formation of each electrode itself and to improve the yield and productivity.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 is to provide a thin plate by forming a concave portion on the front surface, the back surface, or both the front and back surfaces of a substantially central portion of the piezoelectric plate. In a high-frequency piezoelectric vibration device in which at least a pair of excitation electrodes are formed, and a thick reinforcing portion integrally formed around the piezoelectric vibrating region is formed following the piezoelectric vibrating region. Provide an electrode lead-out area of substantially the same thickness as the piezoelectric vibration area in the portion,
An extraction electrode electrically connected to the excitation electrode is formed in the electrode extraction region.

The invention according to claim 2 is characterized in that the electrode lead region and the lead electrode are formed up to the outer peripheral end of the piezoelectric plate, and the lead electrode portion is electrically connected to the outside. A high-frequency piezoelectric vibration device according to claim 1.

The invention according to claim 3 is characterized in that the electrode extraction region and the extraction electrode are formed up to the vicinity of the outer peripheral end of the piezoelectric plate, and the extraction electrode portion is electrically connected to the outside. A high-frequency piezoelectric vibration device according to claim 1.

The invention according to claim 4 is the high-frequency piezoelectric vibration device according to any one of claims 1 to 3, wherein a burying material is provided in at least a part of the electrode lead-out region.

The invention according to claim 5 is the high-frequency piezoelectric vibration device according to claim 4, wherein the burying material is a conductive bonding material.

The invention according to claim 6 is characterized in that a narrow portion is provided in at least a part of the electrode lead-out area to prevent the buried material from flowing out of the electrode lead-out part. A high-frequency piezoelectric vibration device according to item 5.

The invention according to claim 7 is the high-frequency piezoelectric vibration device according to any one of claims 1 to 6, wherein a reinforcing member made of a conductive material is provided on at least a part of the reinforcing portion. is there. Examples of the conductive material include a metal film such as gold and silver, a conductive resin material, and a combination thereof.

The invention according to claim 8 is the high-frequency piezoelectric vibration device according to claim 7, wherein the reinforcing member is formed substantially circumferentially along the reinforcing portion.

[0014]

[Action]

According to the present invention, an electrode lead-out region having substantially the same thickness as the piezoelectric vibration region is provided in a part of the reinforcing portion, and the electrode lead-out region is electrically connected to the excitation electrode. Since the extraction electrode is formed, the extraction electrode does not pass through the edge portion and does not bend in the thickness direction, so that there is no risk of electrode cutting at the edge portion. In addition, since it is not necessary to form an electrode on the inner wall of the concave portion formed by the vibration region and the reinforcing portion, the electrode itself can be easily formed.

According to the fourth aspect of the present invention, the burying material provided in the electrode lead-out region integrally reinforces the thin portion.

According to the fifth aspect of the present invention, since the buried material is a conductive bonding material, it assists the electrical connection between the extraction electrode and the outside together with the reinforcing effect.

According to the sixth aspect of the present invention, the buried material is prevented from flowing out of the electrode lead-out portion by the narrow portion provided in at least a part of the lead-out region.

According to the seventh aspect of the present invention, the piezoelectric vibrating device is reinforced by the reinforcing portion, and the connecting portion of the reinforcing portion with the outside can be set freely.

According to the eighth aspect of the present invention, since the reinforcing member is made of a conductive material and is formed in a substantially circumferential shape along the reinforcing portion, the connecting portion between the reinforcing portion and the outside is formed in the reinforcing portion. Can be set freely.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings, taking a quartz oscillator as an example. FIG. 1 is an exploded perspective view showing a first embodiment of the present invention, and FIG. 2 is a sectional view showing a state in which the components of FIG. 1 are housed and hermetically sealed with a lid plate. The quartz plate 1, which is a piezoelectric body, has a concave shape in which both front and back surfaces at the center of the plate surface are depressed as a whole. The central part of the concave shape is thin and is a piezoelectric vibration region 11,
Excitation electrodes 11a, 1 made of aluminum or the like facing the front and back surfaces
1a is provided. An outer peripheral portion of the piezoelectric vibration region 11 is provided with a reinforcing portion 12 having a thickness several times larger than that of the piezoelectric vibration region, and the thin piezoelectric vibration region is formed by two opposite corner portions of the outer peripheral portion (one corner of the surface). And the other corner of the rear surface) are provided with electrode lead-out regions 13 extending in a groove shape. In the electrode extraction regions 13, extraction electrodes 11 b, 11 b are formed up to the outer peripheral end, respectively. When a frequency of, for example, 90 MHz is obtained for each portion, the thickness of the piezoelectric vibration region is 18 μm, and the thickness of the reinforcing portion is 80 μm. The concave piezoelectric vibration region or the groove-like electrode lead-out region can be formed by a wet etching method, a dry etching method, a sand blast method, or the like, and the electrodes can be formed by a vacuum evaporation method or the like. In addition, aluminum, silver, etc. are used for each electrode material.

The package P for accommodating the quartz plate 1 is made of ceramics such as alumina, and is provided with a lead-out electrode P1 for leading an electrode from the quartz plate accommodating portion to the outside. The quartz plate is housed in the package, and the extraction electrode 13 and the extraction electrode P1
Are electrically conductively bonded by a conductive bonding material S, and airtightly bonded to the upper surface of the package by a cover plate C to obtain a surface-mount type crystal unit. In this embodiment, the groove-shaped electrode lead-out region is filled with a conductive bonding material S1 as a burying material, thereby improving the mechanical strength of the entire quartz plate 1. The electrode lead-out area may be provided on both front and back surfaces as long as mechanical strength can be secured.

A second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a perspective view showing a second embodiment of the present invention. The quartz plate 1, which is a piezoelectric body, has a concave shape in which both front and back surfaces at the center of the plate surface are depressed as a whole.
The central portion of the concave shape is a thin-walled piezoelectric vibrating region 14, which is opposed to the front and back surfaces of the excitation electrode 14 made of aluminum or the like.
a, 14a are provided. An outer peripheral portion of the piezoelectric vibration region 14 is provided with a reinforcing portion 15 having a thickness several times larger than that of the piezoelectric vibration region, and the thin piezoelectric vibration region is provided on two opposite sides of the outer peripheral portion (one side of the surface). And the other side of the back)
Are provided with electrode lead regions 16 extending in a groove shape. In the electrode lead-out areas 16, 16, lead-out electrodes 14b, 14b are formed up to the outer peripheral end, respectively. By forming the electrode lead-out region on the opposite side in this way, the mechanical strength of the quartz plate is improved. Also, as in the above embodiment, the buried material may be filled in the electrode lead-out region.

A third embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a perspective view showing a third embodiment of the present invention, and FIG. 5 is a sectional view taken along line AA of FIG. This embodiment is for describing claim 6 and shows an example of a narrow portion formed in an electrode lead-out region. Quartz plate 2, which is a piezoelectric body, has a concave shape in which only one surface at the center of the plate surface is concave as a whole. The central portion of the concave shape is thin and forms a piezoelectric vibration region 21, and excitation electrodes 21a, 21a made of aluminum or the like are provided facing the front and back surfaces. The outer peripheral portion of the piezoelectric vibration region 21 is provided with a reinforcing portion 22 having a thickness several times larger than that of the piezoelectric vibration region, and the thin piezoelectric vibration region extends in a groove shape at two opposite corners of the outer peripheral portion. Electrode extraction regions 23 and 24 are provided. In the electrode extraction regions 23 and 24, extraction electrodes 21b and 21b are formed up to the outer peripheral end, respectively. The protruding portions 23a and 23b are opposed to the electrode extraction region 23 near the outer peripheral end and the piezoelectric vibration region, respectively.
23c and 23d are provided to form a narrow portion. The projections may be formed integrally during crystal plate processing, or may be formed by applying a bonding material or the like after the processing.
The electrode lead-out region 24 is formed to have a width smaller than that of the electrode lead-out region 23, and a pool portion 24a for storing a buried material or the like is formed in a central portion thereof. The formation of each of these narrow portions can prevent the conductive bonding material used for bonding to the buried material or package from flowing out of the electrode lead-out area, preventing the piezoelectric vibration from being hindered, etc. I do.

A fourth embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a perspective view showing a fourth embodiment of the present invention. This embodiment explains claim 3 and also mentions the connection relationship with the package Q. The quartz plate 3, which is a piezoelectric body, has a concave shape in which both front and back surfaces at the center of the plate surface are depressed as a whole. The center part of the concave shape is thin and the piezoelectric vibration region 31 is formed.
Excitation electrodes 31a, 3 made of aluminum etc.
1a is provided. An outer peripheral portion of the piezoelectric vibration region 31 is provided with a reinforcing portion 32 several times thicker than the piezoelectric vibration region, and the thin piezoelectric vibration region extends in a groove shape toward two opposing sides of the outer peripheral portion. Electrode extraction area 3
3, 33 are provided. This electrode lead-out area 3
Reference numerals 3 and 33 are formed up to the outer peripheral end, and lead electrodes 31b and 31b are formed respectively. Although not shown, an excitation electrode and an extraction electrode are also formed on the back surface. However, the electrode lead-out region is preferably extended in a direction perpendicular to the direction formed on the surface in order to secure the strength of the whole quartz plate. Further, the electrode lead-out region on the back surface may be formed to extend to the outer peripheral end similarly to the configuration shown in the above embodiment. In this case, there is an advantage that the workability is improved when the electrical connection with the package is made by a conductive bonding material. The electrical connection between the extraction electrode 31b on the front surface of the quartz plate 3 and the electrode pad Q1 of the package Q is made via the bonding wire W, and the back surface may be conductively bonded with the conductive bonding material as described above.

A fifth embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a perspective view of a monolithic crystal filter showing a fifth embodiment of the present invention, and FIG.
It is -B sectional drawing. The quartz plate 4, which is a piezoelectric body, has a concave shape in which only one surface at the center of the plate surface is concave as a whole. The central portion of the concave shape is thin and serves as a piezoelectric vibration region 41. An input electrode 45a and an output electrode 46a are formed in parallel on the front surface, and a common electrode 47a corresponding to each of these electrodes is formed on the back surface. Have been. Piezoelectric vibration area 4
1 is provided with a reinforcing portion 42 which is several times thicker than the piezoelectric vibrating region in the outer peripheral portion, and the thinner piezoelectric vibrating region extends in a groove shape toward two opposing sides of the outer peripheral portion. Regions 43 and 44 are provided. The extraction electrodes 45b, 4 are provided in the electrode extraction regions 43, 44, respectively.
6b is formed up to the outer peripheral end. Although not shown, the common electrode 47 on the back surface is connected to the extraction electrode 45b,
46b is led out to the side other than the side from which the lead-out electrode 47b is pulled out. Electrical connection to the outside is made by each of these extraction electrodes.

A sixth embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a perspective view of a monolithic quartz crystal filter according to a sixth embodiment of the present invention. The quartz plate 4 which is a piezoelectric body is almost the same as the fifth embodiment except that the concave portions are formed on the front and back surfaces and the positions where the electrodes are pulled out are different. Therefore, the description of the same structural portions is omitted. Unlike the fifth embodiment, the electrode lead-out areas 48 and 49 are set so as not to be located on straight lines parallel to the respective sides of the outer periphery. The electrode lead-out region 50 on the back surface is also set to a different side from the regions 48 and 49. With such a setting, the thin portion is not biased to a part, so that the mechanical strength of the quartz plate does not decrease.

A seventh embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a perspective view showing a seventh embodiment of the present invention. The quartz plate 5, which is a piezoelectric body, has a concave shape in which both the front and back surfaces at the center of the plate surface are depressed as a whole. The central portion of the concave shape is a thin piezoelectric vibration region 51, and the excitation electrode 51 made of aluminum or the like is opposed to the front and back surfaces.
a, 51a are provided. An outer peripheral portion of the piezoelectric vibration region 51 is provided with a reinforcing portion 52 which is several times thicker than the piezoelectric vibration region, and the thin piezoelectric vibration region extends in a groove shape toward one side of the outer peripheral portion. A lead-out area 53 is provided. An extraction electrode 51b is formed in the electrode extraction region 53. The electrode pads 52a and 52b are also formed on the reinforcing portion. Although not shown, the excitation electrode 51a and the extraction electrode 51 are also provided on the back surface.
b is formed. The electrode lead-out region is filled with a conductive bonding material S2, is electrically connected to the conductive bonding material S2, and is connected to the electrode pads 52a and 52b.
An electrically conductive bonding material S3 is applied on the reinforcing portion in a circumferential shape over the upper portion. As the conductive bonding materials S2 and S3, for example, a polyimide-based conductive bonding material is used. Since the polyimide-based resin has high heat resistance and a small coefficient of thermal expansion, it is hard to apply distortion to the piezoelectric body, and rigid and stable reinforcement is possible. With such a configuration, the mechanical strength of the reinforcing portion can be improved, and the electrode can be led out of the electrode pad formed at an arbitrary position on the reinforcing portion by, for example, the metal elastic thin plate W1.

An eighth embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a perspective view of a monolithic crystal filter showing an eighth embodiment of the present invention, and FIG.
13 is a perspective view from the back side of FIG.
C- in a state where the reinforcing material G2 is joined with the resin adhesive G1 in
It is C sectional drawing. The quartz plate 6, which is a piezoelectric body, has a concave shape in which only one surface at the center of the plate surface is concave as a whole. The central portion of the concave shape is a thin piezoelectric vibration region 61, the input electrode 65a and the output electrode 66a are formed in parallel on the front surface, and the common electrode 67a corresponding to each of these electrodes is formed in the concave portion on the back surface. Are formed. Extraction electrodes 65b and 66b are extended to the outer peripheral end from the input electrode and the output electrode, respectively. A reinforcing portion 62 having a thickness several times as large as that of the piezoelectric vibration region is provided on the outer peripheral portion of the piezoelectric vibration region 61, and the thin piezoelectric vibration region is formed on the back surface by grooves toward two opposing sides of the outer peripheral portion. Electrode extraction regions 63 and 64 extending in the shape of a circle are provided. The electrode extraction regions 63 and 64 have extraction electrodes 67b and 67, respectively.
b is formed up to the outer peripheral end. Although not shown, a buried material such as a resin may be provided in the electrode lead-out region to improve the mechanical strength. Then, an insulating resin adhesive G1 (for example, a polyimide resin) is circumferentially applied to the reinforcing portion on the surface, and a circumferential reinforcing member is provided on an upper portion thereof.
G2 (glass, crystal, metal, resin, etc.) is bonded.
This further enhances the reinforcing effect. The reinforcing member
G2 need not be circumferential, and may be rod-shaped, thin-plate-shaped, or the like as long as it has an effect of reinforcing the thin-walled portion.
Both the resin adhesive G1 and the reinforcing member G2 correspond to the reinforcing member.

The reinforcing member is not limited to the above embodiment, and a metal material may be formed by vapor deposition.
Further, a low melting point glass or a resin material may be formed on the metal surface formed by vapor deposition. Further, although a quartz plate is used as the piezoelectric body in each of the above embodiments, another single crystal piezoelectric body such as lithium tantalate may be used, or a piezoelectric ceramic may be used, although the processing technique is limited. Although the thickness shear vibration is exemplified as the vibration mode, any vibration mode whose frequency depends on the thickness of the piezoelectric body, such as thickness vibration, can be applied to the present invention.

[0030]

According to the present invention, an electrode lead-out region having substantially the same thickness as the piezoelectric vibration region is provided in a part of the reinforcing portion,
Since the extraction electrode electrically connected to the excitation electrode is formed in the electrode extraction region, the extraction electrode does not pass through the edge portion and does not have to be bent in the thickness direction. This eliminates the risk of electrode disconnection, and a highly reliable high-frequency piezoelectric vibration device that does not change over time can be obtained. Further, since it is not necessary to form an electrode on the inner wall of the concave portion formed by the vibrating region and the reinforcing portion, the electrode formation itself is easy, and the yield and productivity can be improved.

According to the fourth aspect of the present invention, since the burying material provided in the electrode lead-out region integrally reinforces the thin portion, a high-frequency piezoelectric vibration device having excellent mechanical strength can be obtained. .

According to the fifth aspect of the present invention, since the buried material is a conductive bonding material, it assists the electrical connection between the extraction electrode and the outside together with the reinforcing effect.

According to the sixth aspect of the present invention, the buried material is prevented from flowing out of the electrode lead-out portion by the narrow portion provided in at least a part of the lead-out region. The conductive bonding material used for bonding to the package can be prevented from flowing out of the electrode lead-out region to the outside, thereby preventing vibration and the like.

According to the seventh aspect of the present invention, the piezoelectric vibration device is reinforced by the reinforcing member, and the connecting portion between the reinforcing portion and the outside can be set freely.

According to the eighth aspect of the present invention, since the reinforcing member is made of a conductive resin and is formed in a substantially circumferential shape along the reinforcing portion, the connecting portion between the reinforcing portion and the outside in the reinforcing portion is formed. Can be set freely.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view after the assembly of FIG. 1;

FIG. 3 is a perspective view showing a second embodiment of the present invention.

FIG. 4 is a perspective view showing a third embodiment of the present invention.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a perspective view showing a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a fifth embodiment of the present invention.

FIG. 8 is a sectional view taken along line BB of FIG. 7;

FIG. 9 is a perspective view showing a sixth embodiment of the present invention.

FIG. 10 is a perspective view showing a seventh embodiment of the present invention.

FIG. 11 is a perspective view showing an eighth embodiment of the present invention.

FIG. 12 is a rear perspective view of FIG. 11;

FIG. 13 is a sectional view taken along line CC of FIG. 11;

FIG. 14 shows a conventional example.

[Explanation of symbols]

1,2,3,4,5,6,9 Quartz plate (piezoelectric body) 11,14,21,31,41,51,61,91 Piezoelectric vibration region 12,15,22,32,42,52,62 , 92 Reinforcement parts 13, 16, 23, 33, 43, 53, 63 Electrode extraction areas 11a, 14a, 21a, 31a, 41a, 51a, 6
1a, 9a Excitation electrode P, Q Package S, S1, S2, S3 Conductive bonding material

Claims (8)

(57) [Claims] 1. The front or back surface of a substantially central portion of a piezoelectric plate
Alternatively, by providing concave portions on both front and rear surfaces, a thin piezoelectric vibration region in which at least a pair of excitation electrodes are formed on the front and back, and a thick reinforcing portion integrally provided therearound following the piezoelectric vibration region are provided. In the formed high-frequency piezoelectric vibration device, an electrode extraction region having substantially the same thickness as the piezoelectric vibration region is provided in a part of the reinforcing portion, and an extraction electrode electrically connected to the excitation electrode is formed in the electrode extraction region. -Frequency piezoelectric vibration device characterized by the following: 2. The high-frequency piezoelectric device according to claim 1, wherein the electrode extraction region and the extraction electrode are formed up to the outer peripheral end of the piezoelectric plate, and the extraction electrode portion is electrically connected to the outside. Vibration device. 3. The high frequency device according to claim 1, wherein said electrode lead-out region and said lead-out electrode are formed up to the vicinity of an outer peripheral end of said piezoelectric plate, and are electrically connected to the outside at said lead-out electrode portion. Piezoelectric vibration device. 4. A buried material is provided in at least a part of the electrode lead-out region.
The high frequency piezoelectric vibration device according to any one of the above. 5. The high-frequency piezoelectric vibration device according to claim 4, wherein the burying material is a conductive bonding material. 6. The high-frequency piezoelectric vibration device according to claim 4, wherein a narrow portion is provided in at least a part of the electrode lead-out region to prevent the buried material from flowing out of the electrode lead-out portion. . 7. At least a part of the reinforcing portion is made of a conductive material.
2. The method according to claim 1, wherein a reinforcing member is provided.
7. The high-frequency piezoelectric vibration device according to any one of claims 6 to 6. 8. The high-frequency piezoelectric vibration device according to claim 7, wherein said reinforcing member is formed in a substantially circumferential shape along the reinforcing portion.