JP2000261275A - Piezoelectric element, piezoelectric filter, and piezoelectric resonance parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a piezoelectric element, where it is difficult that fused solder flows from the terminal electrode side to the energy shut-in type oscillation part side and which has satisfactory resonance characteristics or filter characteristics, without increasing the number of production stages. SOLUTION: An energy shut-in type piezoelectric oscillation part is constituted on a piezoelectric substrate 2, and this piezoelectric oscillation part has oscillation electrodes 3 and 4 formed on the upper face of the piezoelectric substrate 2, and the oscillation electrode 3 is electrically connected to a terminal electrode 10 through a connection electrically conductive part 9. Further, the width of the center part of the connection electrically conductive part 9 is made widest so that fused solder given to the terminal electrode 10 may hardly flow to the oscillation part, and this width is made shortest in at least one side of the terminal electrode connection part of this connection electrically conductive part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element, a piezoelectric filter, and a piezoelectric resonance component, and more particularly, to an electrical connection between a vibration electrode and a terminal electrode constituting an energy trapping type piezoelectric vibration component. The present invention relates to a piezoelectric element, a piezoelectric filter, and a piezoelectric resonance component having improved connection conductive portions.

[0002]

2. Description of the Related Art Conventionally, various piezoelectric resonators and piezoelectric filters utilizing thickness longitudinal vibration and thickness shear vibration have been known.
For example, Japanese Patent Application Laid-Open No. 8-8679 discloses a piezoelectric filter shown in FIGS. 4A and 4B. This piezoelectric filter 51 is configured using a rectangular piezoelectric substrate 52. On the upper surface of the piezoelectric substrate 52, the vibrating electrodes 53, 5
4 are opposed to each other with a predetermined gap. Further, a common electrode 55 is formed so as to face the vibration electrodes 53 and 54 via the piezoelectric substrate 52. Vibrating electrode 53,
A first piezoelectric vibrating portion is constituted by the common electrode 55 and the first piezoelectric vibrating portion.

On the other hand, a second piezoelectric vibrating portion composed of vibrating electrodes 56 and 57 and a common electrode 58 is formed on the piezoelectric substrate 52 in the same manner as described above. The terminal electrode 60 is connected to the vibration electrode 53 of the first piezoelectric vibration section via the connection conductive section 59. On the other hand, the vibration electrode 54 and the vibration electrode 56 are connected via the connection conductive portion 61. In addition, the vibration electrode 57 is electrically connected to the terminal electrode 63 via the connection conductive part 62.

On the lower surface of the piezoelectric substrate 52, common electrodes 55 and 58 are electrically connected to common terminal electrodes 66 via connection conductive portions 64 and 65. Also, the terminal electrode 6
0, 63 and 66 respectively have lead terminals 67 to 69
Are joined by soldering. In the piezoelectric filter 51, when the lead terminals 67 to 69 are joined by solder, the molten solder may flow toward the vibrating portion. For example, when the lead terminal 67 is joined to the terminal electrode 60 by the solder 70, the solder 70 flows on the electrode surface and tends to flow toward the vibration electrode 53. If the solder adheres to the vibrating electrode 53, the vibration of the vibrating part is hindered, and a desired filter characteristic cannot be obtained. Therefore, an epoxy resin layer 71 is formed in the middle of the connection conductive portion 59 so as to cross the vibration electrode 59. That is, the epoxy resin layer 71 is laminated on the connection conductive portion 59, and thereby, the flow of the molten solder to the vibration portion side is suppressed. Similarly, the connection conductive portion 6
An epoxy resin layer 71 is also formed in the middle of 2, 64, 65.

Although not shown in the drawing, in the piezoelectric filter 51 shown in FIG. 4, the epoxy resin layer 71 is formed so as to cover not only the middle of the connection conductive portion 59 but also the vibrating portion. There is also known a method of preventing the solder from flowing to the vibrating portion side.

On the other hand, as shown in FIGS. 5 (a) and 5 (b), Japanese Utility Model Application Laid-Open Publication No. Sho 64-5527 also discloses a piezoelectric filter provided with a structure for preventing the flow of molten solder using an epoxy resin. Is disclosed. That is, in the piezoelectric filter 81, in order to suppress the flow of the molten solder to the vibrating portion including the vibrating electrodes 82 and 83 and the common electrode 84 formed on the lower surface, the epoxy resins 85 and 86 are respectively formed by the vibrating electrodes 83 and 83. The connection conductive portion between the terminal electrode 87 and the connection conductive portion between the common electrode 84 and the terminal electrode 89 are applied.

[0007]

However, as shown in FIGS. 4 and 5, the method of forming an epoxy resin layer in the middle of a connection conductive portion requires a step of applying an epoxy resin, and thus a piezoelectric resonator is required. And the manufacturing process of the piezoelectric filter becomes complicated.

In addition, in a configuration in which not only the connection conductive portion but also the piezoelectric vibrating portion is covered with epoxy resin, since the epoxy resin is applied on the vibrating electrode, there is also a problem that variations in resonance frequency and center frequency are increased. there were.

Further, the bleeding of the epoxy resin when the epoxy resin is applied deteriorates the bonding strength of the lead terminal when the lead terminal is bonded to the terminal electrode, or the epoxy resin bleeds to the vibrating electrode side, thereby causing resonance characteristics and the like. In some cases, the filter characteristics deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to reliably suppress the flow of molten solder to the energy-trap type piezoelectric vibrating portion without increasing the number of manufacturing steps. Accordingly, it is an object of the present invention to provide a piezoelectric element, a piezoelectric filter, and a piezoelectric resonance component using the piezoelectric element having excellent resonance characteristics and filter characteristics.

[0011]

According to the present invention, there is provided a piezoelectric element comprising: a piezoelectric substrate; a vibration electrode formed on the piezoelectric substrate; and a vibration electrode formed on the piezoelectric substrate so as to be separated from the vibration electrode. A terminal electrode that is electrically connected to the outside, and a piezoelectric element that includes a connection conductive portion formed on the piezoelectric substrate for electrically connecting the vibration electrode and the terminal electrode; The width of the central portion is the widest, and the width of at least one of the terminal electrode connecting portion and the vibration electrode connecting portion of the connection conductive portion is the narrowest.

Preferably, the terminal electrode connection portion and the vibration electrode are connected such that a direction connecting the terminal electrode connection portion of the connection conductive portion and the vibration electrode connection portion intersects a direction connecting the terminal electrode and the vibration electrode. The connection portions are shifted.

Further, a piezoelectric filter according to the present invention has a piezoelectric substrate, and first and second resonating portions formed on the piezoelectric substrate, wherein the first resonating portion is formed on one principal surface of the piezoelectric substrate. The first and second vibrating electrodes, which are arranged with a predetermined gap therebetween, are formed on the other main surface of the piezoelectric substrate so as to face the first and second vibrating electrodes via the piezoelectric substrate. A third resonance electrode having a common electrode, wherein the second resonance portion is disposed on the one main surface of the piezoelectric substrate with a predetermined gap therebetween; A common electrode formed on the other main surface of the piezoelectric substrate so as to face the front and back via the piezoelectric substrate, a first and a second terminal electrodes formed on one main surface of the piezoelectric substrate; A third terminal electrode formed on the other main surface of the first terminal and connected to the ground potential; Children electrode first, fourth first connected respectively to the vibrating electrode, and a second connecting conductive portions, the second,
A third connection conductive portion that electrically connects the third vibration electrode, and a fourth connection portion that connects the common electrode and the third terminal electrode.
The first and second connection conductive portions each have the largest width at the center, and have the first and second terminal electrode connection portions and the first and fourth connection conductive portions.
Is characterized in that at least one of the vibrating electrode connection portions has the smallest width.

The piezoelectric element according to the present invention is used for various piezoelectric resonance components. According to a specific aspect of the present invention, the piezoelectric element includes a lead terminal joined to a terminal electrode of the piezoelectric element by soldering. And a leaded piezoelectric resonance component comprising:

Further, the piezoelectric resonance component according to the present invention has a piezoelectric element, a first case material on which the piezoelectric element is mounted, and a first case material joined to the first case material so as to surround the piezoelectric element. A package built-in type piezoelectric resonance component including the two case materials may be used.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

FIGS. 1A and 1B are a plan view showing a piezoelectric filter according to a first embodiment of the present invention and a schematic plan view showing the shape of electrodes on the lower surface. The piezoelectric filter 1 is configured using a rectangular piezoelectric substrate 2. Piezoelectric substrate 2
Can be made of, for example, a piezoelectric ceramic made of lead zirconate titanate-based ceramics or a piezoelectric single crystal such as quartz, but in this embodiment, it is made of lead zirconate titanate-based piezoelectric ceramics.

The piezoelectric substrate 2 is polarized in the direction of arrow P. On an upper surface 2a of the piezoelectric substrate 2, first and second vibrating electrodes 3 and 4 are formed with a predetermined gap therebetween. A common electrode 5 is formed on the lower surface of the piezoelectric substrate 2 so as to face the vibration electrodes 3 and 4 on the front and back. The first and second vibrating electrodes 3 and 4 and the common electrode 5 constitute a first piezoelectric vibrating section.

On the upper surface of the piezoelectric substrate 2, a vibrating electrode 4
The third and fourth vibrating electrodes 6 and 7 are formed separately from each other. A common electrode 8 is formed so as to face the third and fourth vibrating electrodes 6 and 7 via the piezoelectric substrate 2.
A second piezoelectric vibrating section is constituted by the vibrating electrodes 6 and 7 and the common electrode 8.

The first and second piezoelectric vibrating portions operate as energy-trapping type resonators utilizing the thickness slip mode. The first vibration electrode 3 is electrically connected to the first terminal electrode 10 via the connection conductive part 9. Also,
The second and third vibrating electrodes 4 and 6 are electrically connected via the connection conductive portion 11. The fourth vibration electrode 7 is electrically connected to the second terminal electrode 13 via the connection conductive part 12.

On the lower surface of the piezoelectric substrate 2, common electrodes 5 and 8 are electrically connected to terminal electrodes 14 via connection conductive portions 15 and 16, respectively. Terminal electrode 10,
Reference numeral 13 is formed on the upper surface of the piezoelectric substrate 2 along each edge formed by the end surfaces 2b and 2c and the upper surface 2a.

On the other hand, the terminal electrode 14 is formed at the center on the lower surface of the piezoelectric substrate 2. The terminal electrode 14 is connected to the ground potential. When an input signal is applied to the first terminal electrode 10, the first and second piezoelectric vibrating portions vibrate, and an output signal is taken out from the second terminal electrode 13.

The feature of the present embodiment lies in the shape of the connection conductive portions 9 and 12. That is, the connection conductive portion 9,
12 has the largest width at the center in the longitudinal direction, and the terminal electrode connection portions 9a, 12 of the connection conductive portions 9, 10.
a and the vibration connecting portions 9b and 12b have the narrowest widths.

The direction connecting the terminal electrode connecting portions 9a, 12a of the connection conductive portions 9, 12 and the vibrating electrode connecting portions 9b, 12b corresponds to the direction connecting the terminal electrode 10 and the vibrating electrode 3 and the direction connecting the vibrating electrode 7. The direction intersects with the direction connecting the terminal electrode 13. In other words, in FIG. 1A, in the direction orthogonal to the length direction of the piezoelectric substrate 2, the connection conductive portions 9 and
The connection portions at both ends of 12 are shifted.

In the piezoelectric filter 1, the connecting conductive parts 9, 12
Has the shape as described above, for example, the terminal electrode 1
When the lead terminals are soldered to 0 and 13, the molten solder can be reliably prevented from flowing to the vibrating section. That is, as shown in an enlarged manner in FIG. 2, the molten solder 17 is placed on the terminal electrode 10 in order to connect the lead terminal 21.
Is applied, the molten solder 17 flows not only to the terminal electrode 10 but also to the connection conductive part 9 side. However, since the connecting conductive portion 9 is not formed in a thin line shape but is configured to have the largest width at the center in the length direction, that is, since the connecting conductive portion 9 has a certain area, the solder that has been cast cannot be used. The molten solder stays on the connection conductive part 9 and the molten solder does not easily flow to the vibration electrode 3.

In addition, since the width of the terminal electrode connection portion 9a of the connection conductive portion 9 is the smallest, it is difficult for molten solder to enter the connection conductive portion 9 side. Further, even when a larger amount of molten solder is applied than the molten solder 17 shown in FIG. 2, since the width of the vibration electrode side connection portion 9 b of the connection conductive portion 9 is the smallest, vibration It is difficult for the molten solder to migrate to the electrode 3 side.

Therefore, when a lead terminal (not shown) is joined to the terminal electrode 10 by soldering, even if a sufficient amount of solder is applied, it is difficult for the molten solder to flow to the vibration electrode 3 side. Similarly, since the connection conductive portion 12 is configured similarly to the connection conductive portion 9, it is difficult for the molten solder to flow into the vibration electrode 7 side.

Therefore, when the lead terminals are joined to the piezoelectric filter 1, it is difficult for the molten solder to flow to the vibrating portion, so that the desired filter characteristics can be reliably obtained. Moreover, since the flow of the molten solder to the piezoelectric vibrating portion is suppressed by devising the shape of the connection conductive portions 9 and 12, there is no need to separately perform a step of applying an epoxy resin or the like.

In the above embodiment, the terminal electrodes 10, 1
The case where the lead terminals are joined to 3, 14 has been described as an example, but the piezoelectric filter 1 is mounted on a case substrate by euro soldering or the like, and a package type chip type formed by joining a metal cap on the case substrate. It may be configured as a piezoelectric resonance component. Even in this case, the molten solder
Since it is difficult to flow from the terminal electrodes 10 and 13 to the piezoelectric vibrating portion side, it is possible to provide a piezoelectric resonance component having similarly good filter characteristics.

In the piezoelectric filter 1 of the above embodiment,
Although the connecting conductive portions 9 and 12 are configured as described above, the connecting conductive portions 15 and 16 formed on the lower surface side of the piezoelectric substrate 2 are also formed in the same shape, so that the molten solder is applied to the piezoelectric vibrating portion side. Casting can be further suppressed.

In the present invention, the shape of the connecting conductive portions does not necessarily have to be the same as those of the connecting conductive portions 9 and 12 shown in FIG. That is, FIG.
As shown in (c), the shape of the connection conductive part 9 is as follows.
There is no particular limitation as long as the width is the largest at the center in the length direction and the width is the smallest in at least one of the terminal electrode connection portion and the vibration electrode connection portion.

In the connection conductive portion 9A shown in FIG. 3A, both side edges of the connection conductive portion 9A are curved, and the width is the largest at the center in the length direction. The connection conductive portion 9B shown in FIG. 3B is configured to have a diamond shape. Further, the connection conductive portion 9C shown in FIG. 3C has a rectangular region at the center, and narrow conductive portions are formed on both sides of the rectangular region.

The piezoelectric filter 1 can be configured as a lead-equipped piezoelectric resonance component by joining the lead terminals 21 to 23 with molten solder, as shown by alternate long and short dash lines 21 to 23 in FIG. Alternatively, a chip-type piezoelectric resonance component in which the piezoelectric filter 1 is joined to the case substrate via solder and the piezoelectric filter 1 is sealed using a metal cap may be used.

Although the piezoelectric filter 1 has a piezoelectric filter including two piezoelectric vibrating portions using the thickness-slip mode, the piezoelectric element according to the present invention has only one piezoelectric vibrating portion. Piezoelectric resonator, or a piezoelectric filter having three or more piezoelectric vibrating portions. Further, a piezoelectric filter using another vibration mode such as a thickness longitudinal mode other than the thickness slip mode may be used. It may be an element.

[0035]

In the piezoelectric element according to the present invention, the width of the center of the connection conductive portion is the largest, and the width is minimized in at least one of the terminal electrode connection portion and the vibration electrode connection portion of the connection conductive portion. Therefore, even if the molten solder given to the terminal electrode flows to the connection conductive part side,
First, not only is it difficult for molten solder to flow into
Since the connection conductive portion has a certain large area, the molten solder is less likely to migrate to the vibration electrode side. Therefore, it is possible to provide a piezoelectric element having excellent resonance characteristics and filter characteristics.

Further, in the conventional piezoelectric element, the transfer of the molten solder to the piezoelectric vibrating portion side was prevented by using an epoxy resin or the like, but a complicated operation of applying the epoxy resin was forced. On the other hand, in the piezoelectric element according to the present invention,
Since the transfer of the molten solder to the piezoelectric vibrating portion side is prevented by devising the shape of the connection conductive portion, it is not necessary to perform a complicated process such as applying an epoxy resin. Therefore, the manufacturing process of the piezoelectric element can be simplified.

In the present invention, when the direction connecting the terminal electrode connection portion and the vibration electrode connection portion of the connection conductive portion intersects with the direction connecting the terminal electrode and the vibration electrode, the length of the connection conductive portion is determined. In other words, since the length of the connection conductive portion from the terminal electrode connection portion to the vibration electrode connection portion is increased, the transfer of the molten solder to the piezoelectric vibration portion side can be more effectively suppressed.

[0038] In the piezoelectric filter according to the present invention, the first and second resonating portions are formed on the piezoelectric substrate, and the first and second connecting conductive portions each have the largest width at the center. In addition, since the width of the connection conductive portion is the narrowest in at least one of the first and second terminal electrode connection portions and the first and fourth vibration electrode connection portions, the case of the piezoelectric element according to the present invention is the same. Similarly, when the molten solder is applied to the terminal electrode, the migration of the molten solder to the resonance portion side can be reliably suppressed. Therefore, it is possible to provide a piezoelectric filter having good filter characteristics without obtaining complicated steps.

According to the fourth aspect of the present invention, by joining the lead terminals to the terminal electrodes of the piezoelectric element according to the present invention by soldering, a leaded piezoelectric resonance component having good resonance characteristics and filter characteristics can be manufactured at a low cost. Can be provided.

[Brief description of the drawings]

FIGS. 1A and 1B are a plan view showing a piezoelectric filter as a piezoelectric element according to an embodiment of the present invention, and a schematic plan view showing an electrode shape on a lower surface of a piezoelectric substrate.

FIG. 2 is a partially cutaway plan view showing a state in which molten solder stays in a connection conductive portion in the piezoelectric filter of the embodiment shown in FIG.

FIGS. 3A to 3C are partially cutaway plan views for explaining a modification of the shape of the connection conductive portion in the piezoelectric element according to the present invention.

4A and 4B are a plan view and a bottom view illustrating an example of a conventional piezoelectric element.

FIGS. 5A and 5B are a plan view and a bottom view for explaining another example of a conventional piezoelectric element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piezoelectric filter as a piezoelectric element 2 ... Piezoelectric substrate 3 ... First vibration electrode 4 ... Second vibration electrode 5 ... Common electrode 6 ... Third vibration electrode 7 ... Fourth vibration electrode 8 ... Common electrode 9, 12 ... connecting conductive parts 10, 13, 14 ... terminal electrodes 9A to 9C ... connecting conductive parts 21 to 23 ... lead terminals

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomoaki Niguchi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. (Reference) 5J108 AA07 BB04 CC04 DD02 EE11 FF07 FF15

Claims (5)

[Claims] A piezoelectric substrate, a vibration electrode formed on the piezoelectric substrate, a terminal electrode formed on the piezoelectric substrate so as to be separated from the vibration electrode, and electrically connected to the outside; In a piezoelectric element including a connection conductive portion formed on the piezoelectric substrate to electrically connect the vibration electrode and the terminal electrode, a width of a central portion of the connection conductive portion is the largest, A piezoelectric element, wherein the width of at least one of the terminal electrode connection portion and the vibration electrode connection portion of the connection conductive portion is the smallest. 2. A terminal electrode connection portion of the connection conductive portion,
2. The piezoelectric element according to claim 1, wherein a direction connecting the vibration electrode connection portion intersects a direction connecting the terminal electrode and the vibration electrode. 3. A piezoelectric filter having a piezoelectric substrate and first and second resonance portions formed on the piezoelectric substrate, wherein the first resonance portion has a predetermined gap on one main surface of the piezoelectric substrate. A first and a second vibrating electrodes arranged at a distance from each other;
A common electrode formed on the other main surface of the piezoelectric substrate so as to oppose the first and second vibrating electrodes via the piezoelectric substrate, and a second resonance portion is provided on one main surface of the piezoelectric substrate. A third and a fourth vibrating electrode arranged at a predetermined gap in
A third electrode formed on the other main surface of the piezoelectric substrate so as to face the third and fourth vibrating electrodes via the piezoelectric substrate, and a first electrode formed on one main surface of the piezoelectric substrate. A second terminal electrode, a third terminal electrode formed on the other main surface of the piezoelectric substrate and connected to the ground potential, and a first and fourth vibrating electrode connected to the first and second terminal electrodes. A first and a second connection conductive part respectively connected to the first electrode, a third connection conductive part electrically connecting the second and third vibrating electrodes, a common electrode and a third terminal electrode, And a fourth connection conductive portion for connecting the first and second terminal electrode connections, wherein the first and second connection conductive portions each have the largest width at the center, and have the first and second terminal electrode connections. At least one of the portion and the first and fourth vibrating electrode connection portions has the narrowest width. That, the piezoelectric filter. 4. A piezoelectric resonance component, comprising: the piezoelectric element according to claim 1; and a lead terminal joined to a terminal electrode of the piezoelectric element by soldering. 5. The piezoelectric element according to claim 1 or 2, a first case material on which the piezoelectric element is mounted, and joined to the first case material so as to surround the piezoelectric element. A piezoelectric resonance component, comprising: a second case material.