JP2003152494A - Piezoelectric resonance component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load capacitance built-in type piezoelectric resonance component which is so excellent in reliability that a short circuit can hardly occur between adjacent external electrodes thereof even if the component is miniaturized. SOLUTION: The load capacitance built-in type piezoelectric resonance component 1 has a case having a case substrate 2 which is like a rectangle plate and a piezoelectric resonator 4 sealed in the case. Load capacitance to be connected to the resonator 4 is formed in the substrate 2. A first and second external electrodes 7, 8 used as input/output terminals and a third and fourth external electrodes 9, 10 connected to a ground potential are arranged on four corner portions or the vicinities thereof of the substrate 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric resonance component used in, for example, a piezoelectric oscillator having a built-in load capacitance or a piezoelectric filter, and more specifically, a piezoelectric resonator having a plurality of external electrodes formed on the lower surface of a case substrate. Resonance component improvement.

[0002]

2. Description of the Related Art Heretofore, various piezoelectric oscillators having a built-in load capacitance and using an energy trapping type piezoelectric element have been proposed. For example, Japanese Patent No. 266295 discloses a piezoelectric oscillator 1 with a built-in load capacitance shown in FIGS. 6 and 7.
01 is disclosed. In this piezoelectric oscillator 101, a plate-shaped piezoelectric resonator 102 is used. Piezoelectric resonator 1
Reference numeral 02 denotes an energy trap type piezoelectric resonator utilizing thickness longitudinal vibration.

On the upper surface of the piezoelectric resonator 102, a sealing substrate 103 having a recess 103a for preventing the vibration of the piezoelectric vibrating portion is attached. In addition, a sealing substrate 104 having a recess 104a is also attached below.

In the piezoelectric oscillator 101, external electrodes 111 to 113 are formed for connection with the outside. The external electrodes 111 and 112 are the first and second electrodes of the piezoelectric resonator 102.
Is connected to the vibrating electrode. In addition, the external electrodes 111,
Reference numeral 112 has not only the end face of the laminated body but also the upper surface, both side surfaces, and the lower surface. On the other hand, the external electrode 113 is formed so as to cross the lower surface from the upper surface of the laminated body through both side surfaces thereof, and a capacitor configuring a load capacitance is configured between the external electrode 113 and the external electrodes 111 and 112. .

[0005]

As shown in FIG. 6, in the piezoelectric oscillator 101, the external electrodes 111 and 112 are provided.
Has a portion wound around the periphery of the laminated body so as to reach the entire width of the lower surface from the upper surface of the laminated body through both side surfaces. Therefore, the piezoelectric oscillator 10 is provided on the upper surface and the lower surface of the laminated body.
In one length direction, at least three electrodes, the external electrodes 111 to 113, and two gaps for preventing a short circuit of the three electrodes must be formed.

However, when the size of the piezoelectric oscillator 101 is reduced, that is, when the size of the piezoelectric oscillator 101 in the lengthwise direction is reduced, an appropriate interval is provided to prevent short circuit of the three external electrodes. Are becoming difficult to form.

Even if three external electrodes can be formed with a gap therebetween, there is a risk that adjacent external electrodes may be short-circuited by solder balls or the like when they are laminated on a printed circuit board or the like. Further, there is a possibility that adjacent external electrodes may be short-circuited due to ion migration or adhesion of whiskers during actual use. Therefore, conventionally, it has been difficult to further reduce the size of a piezoelectric resonance component such as a piezoelectric oscillator having a built-in load capacitance.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a piezoelectric resonance component having a built-in load capacitance in which short-circuiting of adjacent external electrodes does not easily occur even when miniaturization is promoted. To do.

[0009]

According to a broad aspect of the present invention, a piezoelectric element having one energy vibrating piezoelectric vibrating portion and an energy trap vibrating portion of the piezoelectric element are sealed. A case having a rectangular plate shape, the lower surface of the case substrate is a mounting surface, and the lower surface of the case substrate is formed at four corners or in the vicinity thereof, respectively. The first to fourth external electrodes are formed, the first and second external electrodes form input / output terminals, and the third and fourth external electrodes are connected to the ground potential. A piezoelectric resonance component is provided which has a built-in load capacitance in the case substrate.

In the piezoelectric resonance component according to the present invention, on the lower surface of the case substrate, at four corners or in the vicinity thereof,
First to fourth external electrodes are formed, the first and second external electrodes form input / output terminals, and the third and fourth external electrodes are connected to the ground potential. Since the load capacitance is formed by the case substrate, two external electrodes may be formed along one side of the lower surface of the piezoelectric resonance component. Therefore, even when miniaturization of the piezoelectric resonance component is promoted, it is possible to prevent a short circuit between adjacent external electrodes.

The structure of the case in the piezoelectric resonant component according to the present invention is not particularly limited as long as it has the case substrate, but the case substrate and the piezoelectric element mounted on the case substrate are sealed in the case substrate. It may have a joined cap material, and in that case, according to the present invention, it is possible to reduce the size of the load capacity built-in piezoelectric resonance component having the sealing structure.

In this case, as the piezoelectric element, a strip-shaped piezoelectric substrate polarized in the length direction and first and second resonance electrodes arranged so as to overlap each other at the center in the length direction of the piezoelectric substrate. An energy confinement type piezoelectric resonator having a thickness-sliding mode is preferably used. Further, in the present invention, the piezoelectric element has a rectangular plate-like shape, and is laminated on the case substrate in a state in which a space for preventing the piezoelectric element from disturbing the vibration of the piezoelectric vibrating portion is secured, and the case is According to the present invention, a second case substrate laminated on the upper surface of the piezoelectric element may be further provided.
It is possible to reduce the size of a laminated type piezoelectric resonance component with a built-in load capacitance. In this case, as the piezoelectric element, a rectangular plate-shaped piezoelectric substrate polarized in the thickness direction and a first piezoelectric substrate partially formed on the upper surface and the lower surface of the piezoelectric substrate so as to be adjacent to each other with the piezoelectric substrate interposed therebetween. , And the second excitation electrode, and an energy trap type piezoelectric resonator utilizing the thickness extensional vibration mode is preferably used.

In another particular aspect of the present invention, the first and second aspects are provided.
External electrodes are arranged on the lower surface of the case substrate at the corners on both sides of the diagonal line or in the vicinity thereof, and therefore the input / output electrodes are arranged at diagonal positions, so that a complicated directional sorting work at the time of stacking is performed. It can be simplified.

In another particular aspect of the present invention, the third and third aspects are provided.
The fourth external electrode is electrically connected to the lower surface of the case substrate, and therefore either the third or fourth external electrode may be connected to an electrode connected to the ground potential, such as a printed circuit board. It is possible to simplify the mounting work.

In the present invention, the form of the load capacitance formed on the case substrate is not particularly limited.
It can be constituted by a capacitance between the second external electrode and the third and fourth external electrodes.

However, the load capacitance may be formed by further forming internal electrodes or the like in the case substrate. In the present invention, the first to fourth external electrodes may be formed only on the lower surface of the case substrate, or may be formed from the lower surface of the case substrate to the side surfaces. In that case, When mounting on a printed circuit board, electrical connection can be achieved by utilizing the side surface portion of the external electrode, and the mounting strength can be effectively increased.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

1 (a) and 1 (b) are a perspective view and an exploded perspective view showing the appearance of a piezoelectric resonance component according to a first embodiment of the present invention. The piezoelectric resonance component 1 has a case including a case substrate 2 having a rectangular plate shape and a cap member 3.

An energy trap type piezoelectric resonator 4 utilizing a thickness sliding mode is mounted on the case substrate 2. The piezoelectric resonator 4 is an elongated rectangular plate-shaped piezoelectric substrate 4a.
And the piezoelectric substrate 4a at the center in the length direction of the piezoelectric substrate 4a.
And a pair of resonance electrodes 4b and 4c that are opposed to each other. Resonance electrode 4b are led to one end face from the center of the upper surface of the piezoelectric substrate 4a, and are chosen to electrode extension 4b ₁ provided on the lower surface. The resonance electrode 4c extends from the center of the lower surface of the piezoelectric substrate 4a to the end surface on the opposite side to the end surface on the side where the resonance electrode 4b is extended and is provided on the upper surface.
It is linked to c ₁ .

The piezoelectric substrate 4a is made of piezoelectric ceramics such as lead zirconate titanate-based ceramics and is polarized in the length direction. In this embodiment, the energy trap type piezoelectric resonator 4 using the thickness sliding mode is used, but the piezoelectric substrate 4a has a similar electrode structure, and the piezoelectric substrate 4a is polarized in the thickness direction. An electrode resonator may be used.

An energy trap type piezoelectric resonator utilizing another vibration mode may be used. The piezoelectric resonator 4 is bonded onto the case substrate 2 with conductive adhesives 5 and 6, and is electrically connected to the external electrodes 7 and 8 formed on the upper surface 2a of the case substrate 2. External electrode 7,
8 is formed not only on the upper surface 2a of the case substrate 2 but also on the lower surface 2b through the side surface. First and second
The external electrodes 7 and 8 of the external electrode 7 are formed on the lower surface 2b of the case substrate 2 as shown in FIG.
It is formed so as to reach the vicinity of corners located on both sides of the diagonal line.

On the other hand, the third and fourth external electrodes 9, so as to reach the upper surface 2a from the lower surface of the case substrate 2 through the side surfaces,
10 are formed. Third and fourth external electrodes 9, 10
Is formed in the vicinity of a corner portion different from the corner portion where the external electrodes 7 and 8 are formed.

The capacitance between the external electrodes 9 and 10 and the external electrodes 7 and 8 constitutes a load capacitance connected to the piezoelectric resonator 4. The case substrate 2 is made of a dielectric ceramic having a high relative dielectric constant such as BaTiO ₃ in order to configure the load capacitance, and an internal electrode (not shown) facing the external electrodes 7 and 9 is provided therein. Then, a capacitor C1 is formed between the external electrodes 7 and 9, and another internal electrode (not shown) facing the external electrodes 8 and 10 is provided to form a capacitor C2 between the external electrodes 8 and 10. There is.

On the upper surface of the case substrate 2, the insulating adhesive 1
1, the cap material 3 is joined. As a result, the piezoelectric resonance element 4 is sealed in the case formed of the case substrate 2 and the cap material 3. Cap material 3
Has an opening 3a opened downward. The cap material 3 is
It can be made of synthetic resin or metal.
When the cap material 3 is made of a conductive material such as metal, the piezoelectric resonator 4 can be electromagnetically shielded by the cap material 3.

The features of the present embodiment are that the case substrate 2 is used to form a load capacitance and that the first to fourth parts are used.
The external electrodes 7 to 10 are formed on the lower surface 2b of the case substrate 2 near the four corners, respectively.

That is, in the piezoelectric resonance component 1, both the long side and the short side of the rectangular plate-shaped case substrate 2 are 2
One outer electrode and one gap between the outer electrodes are formed. Therefore, even when miniaturization is advanced, it is possible to reliably prevent a short circuit between adjacent external electrodes, for example, between the external electrodes 8 and 9 or between the external electrodes 7 and 9.

FIG. 2 is a schematic plan view schematically showing the arrangement of external electrodes on the lower surface of the piezoelectric resonance component of this embodiment and the electrical connection between the external electrodes 7-10. In addition, in the present embodiment, the first and second external electrodes 7 and 8, that is, the external electrodes 7 and 8 as input / output electrodes connected to the resonance electrodes of the piezoelectric resonator 4 are provided near the corner positions at both ends of the diagonal line. Has been formed. Therefore, even when the piezoelectric resonance component 1 is rotated 180 degrees around the perpendicular line passing through the center of the case substrate 2, the external electrodes 7 and 8 are merely replaced with each other, and the function as a piezoelectric oscillator is achieved. And characteristics are not impaired. That is, when the capacitances of the capacitors C1 and C2, which are schematically shown in FIG. 2, are the same, the piezoelectric oscillation is performed regardless of which of the external electrode 7 and the external electrode 8 is the input electrode and the output electrode. The characteristics of the child are not impaired. Therefore, the complicated direction selection work at the time of mounting can be simplified.

FIG. 3 is a diagram showing a piezoelectric resonance component according to a second embodiment of the present invention, in which (a) is a perspective view showing the appearance,
(B) is an exploded perspective view.

In the piezoelectric resonance component 21 of the second embodiment, case substrates 23 and 24 made of piezoelectric ceramics are laminated above and below a plate-shaped piezoelectric resonator 22 with an adhesive (not shown) interposed therebetween. .

The piezoelectric resonator 22 is an energy trap type piezoelectric resonator utilizing a thickness extensional vibration mode. The piezoelectric resonator 22 has a rectangular plate-shaped piezoelectric substrate 22a and first and second excitation electrodes 22b and 22c provided in the center of the piezoelectric substrate 22a so as to overlap each other with the piezoelectric substrate 22a interposed therebetween. The piezoelectric substrate 22a is made of piezoelectric ceramics such as lead zirconate titanate-based ceramics, and is polarized in the thickness direction.

The excitation electrode 22b is connected to the extraction electrode 22d, and the excitation electrode 22c is connected to the extraction electrode 22e. The extraction electrode 22d is provided in the vicinity of a corner portion of the piezoelectric substrate 22, and the extraction electrode 22e is provided in the vicinity of a corner portion located on the opposite side of a diagonal line from the corner portion where the extraction electrode 22d is provided. .

On the other hand, the case substrates 23 and 24 are made of BaTi.
It is composed of a dielectric ceramic such as O ₃ . A recess is formed on the lower surface of the case substrate 23 so as not to interfere with the vibration of the piezoelectric vibrating portion, and a recess 24 a is also formed on the upper surface of the case substrate 24.

As shown in FIGS. 3A and 3B, the first
-The 4th external electrodes 25-28 are formed so that it may reach a lower surface and an upper surface from the side surface of a laminated body. External electrode 25
Is connected to the extraction electrode 22d on the side surface of the stacked body, and the external electrode 26 is connected to the extraction electrode 22e. The external electrodes 27 and 28 are provided in the corner portion of the case substrate 24 near the corner portions other than the corner portions where the external electrodes 25 and 26 are provided.

The piezoelectric resonance component 21 of this embodiment has a capacitor formed between the external electrodes 25 and 26 and the external electrodes 27 and 28, and is operated as a load capacity built-in piezoelectric oscillator.

That is, the external electrodes 27, 28 are connected to the ground potential during use, and the capacitors for forming the load capacitances between the external 27, 28 and the external electrodes 25, 26 are the same as in the first embodiment. Similar to the case substrate 2, at least one of the case substrates 23 and 24 is provided with an internal electrode.

The upper surface 24b of the case substrate 24 is
The electrodes 31 to 34 connected to the external electrodes 25 to 28 are formed, but the electrodes 31 to 34 are not always necessary. However, by forming the electrodes 31 to 34, the electrostatic capacitance is taken out also between the electrodes 31 and 32 and the electrodes 33 and 34.

Also in the piezoelectric resonance component of this embodiment, since the external electrodes 25 to 28 are formed as described above,
When the piezoelectric resonance component 21 is mounted, in order to prevent a short circuit between one external electrode and two external electrodes adjacent thereto on both the long side and the short side of the rectangular bottom surface of the case substrate 24. It suffices that one gap be formed in each. Therefore, even when the miniaturization is promoted similarly to the piezoelectric resonance component 1 of the first embodiment, it is possible to reliably prevent the short circuit between the adjacent external electrodes.

Further, also in this embodiment, the external electrode 2
Since 5 and 26 are arranged on both sides of the diagonal line, the complicated direction selection work at the time of mounting can be simplified as in the first embodiment.

In this embodiment, the case substrates 23 and 2 are
Although a concave portion for preventing vibration of the piezoelectric vibrating portion is formed in No. 4, the piezoelectric layer is formed by an adhesive layer having an opening so as to form a space for preventing vibration of the piezoelectric vibrating portion without forming the concave portion. The case substrates 23 and 24 may be attached to the resonator 22.

Further, in this embodiment, the capacitance is taken out also in the case substrate 23, but the case substrate 24
Alternatively, the electrostatic capacitance may be taken out only at. That is, the case substrate 23 does not necessarily have to be made of a dielectric ceramic having a high relative dielectric constant.

In the first and second embodiments, the external electrodes are formed so as to extend from the lower surface to the side surface of the case substrate of the piezoelectric resonance component, but as shown in the schematic bottom view in FIG. 4 (a). In addition, the notches 31a to 31d may be formed on the side surfaces of the case substrate 31, and the first to fourth external electrodes 32 to 35 may be formed so as to cover the notches 31a to 31d formed on the side surfaces. Even in this case, the first and second external electrodes 32 and 33 are located on both sides of the diagonal line on the lower surface of the case substrate 31. The external electrodes 32 to 35 are formed so as to reach the corners of the lower surface of the case substrate. That is, in the present invention, the external electrodes may be formed so as to reach the corners.

Further, as shown in FIG. 4 (b), the notches 31a to 31d may be formed in the corner portion of the case substrate 31.

Further, as schematically shown in the lower surface of the case substrate in FIG. 5, the third and fourth external electrodes 44, 45 connected to the ground potential may be connected by the connection conductive portion 46. In the case substrate 41 shown in FIG. 5, the first and second external electrodes 42, 43 are arranged at corner portions on both sides of a diagonal line of the case substrate 41.

Further, in the above-described embodiments and modifications, the first and second external electrodes are arranged on both sides of a diagonal line on the rectangular case substrate and are connected to the ground potential. Although the external electrode of 1 was formed in the vicinity of the remaining corners, the first external electrode and the third external electrode may be arranged on both sides of the diagonal line.

[0045]

The piezoelectric resonance component according to the present invention is provided with the first and second external electrodes forming the input / output terminals and the third and fourth external electrodes connected to the ground potential. Since the first to fourth external electrodes are formed on the lower surface of the rectangular plate-shaped case substrate at four corners or in the vicinity thereof, respectively, even when the size of the piezoelectric resonance component is reduced, the case substrate Since it is only necessary to form one gap between one external electrode and two adjacent external electrodes on any side of the lower surface, it is possible to reliably suppress a short circuit between the adjacent external electrodes.

Therefore, according to the present invention, the size is reduced,
It is possible to provide a piezoelectric resonance component with a built-in load capacitance, which has excellent electrical connection reliability.

[Brief description of drawings]

1A and 1B are a perspective view and an exploded perspective view showing an appearance of a piezoelectric resonance component according to a first embodiment of the invention.

FIG. 2 is a schematic bottom view of the piezoelectric resonance component of the first embodiment.

3A and 3B are a perspective view and an exploded perspective view showing an external appearance of a piezoelectric resonance component according to a second embodiment of the present invention.

4 (a) and 4 (b) are views for explaining a modified example of the piezoelectric resonance component according to the present invention, and are bottom views showing modified examples in which external electrode shapes are different.

FIG. 5 is a schematic bottom view for explaining still another modified example of the piezoelectric resonant component of the present invention.

FIG. 6 is a sectional view for explaining an example of a conventional piezoelectric oscillator with a built-in load capacitance.

7 is a perspective view of the piezoelectric resonant component shown in FIG.

[Explanation of symbols]

1 ... Piezoelectric resonance component 2 ... Case substrate 3 ... Cap material 4 ... Piezoelectric resonator 4a ... Piezoelectric plate 4b, 4c ... Resonant electrodes 5, 6 ... Conductive adhesive 7-10 ... 1st-4th external electrodes 21 ... Piezoelectric resonance component 22 ... Piezoelectric resonator 22a ... Piezoelectric substrate 22b, 22c ... Resonant electrodes 23, 24 ... Case substrate 25-28 ... 1st-4th external electrodes 31 ... Case substrate 32-35 ... First to fourth external electrodes 41 ... Case substrate 42 to 45 ... First to fourth external electrodes

Claims (9)

[Claims] 1. A piezoelectric element having one energy-encapsulation type piezoelectric vibrating portion, and a case for sealing the energy-confining vibrating portion of the piezoelectric element, wherein the case is a rectangular plate. Shaped case substrate, the lower surface of the case substrate is a mounting surface, and the first to fourth external electrodes are formed at four corners or in the vicinity of the lower surface of the case substrate. , The first and second external electrodes form input / output terminals, the third and fourth external electrodes are connected to the ground potential, and the case substrate has a built-in load capacitance. , A piezoelectric resonance component. 2. The piezoelectric resonance component according to claim 1, wherein the case further includes a cap member bonded to the case substrate so as to seal the piezoelectric element mounted on the case substrate. 3. The piezoelectric element has a strip-shaped piezoelectric substrate polarized in the length direction, and first and second resonance electrodes arranged so as to overlap each other at the center of the piezoelectric substrate in the length direction. The piezoelectric resonance component according to claim 2, wherein the piezoelectric resonance component is an energy trap type piezoelectric resonator utilizing a thickness shear mode. 4. The piezoelectric element has a rectangular plate shape, and is laminated on the case substrate in a state where a space for preventing the piezoelectric element from disturbing the vibration of the piezoelectric vibrating section is secured. The piezoelectric resonance component according to claim 1, further comprising a second case substrate laminated on the upper surface of the piezoelectric element. 5. The first piezoelectric element is partially formed on the upper surface and the lower surface of the piezoelectric substrate so as to be adjacent to the rectangular plate-shaped piezoelectric substrate polarized in the thickness direction with the piezoelectric substrate interposed therebetween. The piezoelectric resonance component according to claim 4, wherein the piezoelectric resonance component comprises a second excitation electrode and is an energy trap type piezoelectric resonator utilizing a thickness longitudinal vibration mode. 6. The piezoelectric resonance according to claim 1, wherein the first and second external electrodes are arranged on the lower surface of the case substrate at corners on both sides of a diagonal line or in the vicinity thereof. parts. 7. The first to sixth external electrodes are electrically connected to the lower surface of the case substrate.
The piezoelectric resonance component according to any one of 1. 8. The load capacitance according to claim 1, wherein the load capacitance is constituted by a capacitance between the first and second external electrodes and the third and fourth external electrodes. 2. The piezoelectric resonance component described in. 9. The piezoelectric resonance component according to claim 1, wherein the first to fourth external electrodes are formed so as to extend from a lower surface to a side surface of the case substrate.