JPH0397313A - Chip type piezoelectric filter - Google Patents

Abstract

PURPOSE:To save work and to miniaturize the component by forming at least one of capacitance electrodes of a coupling capacitor part to the surface of a sealing base toward an external side and connecting a vibration electrode of a vibration part and a capacitance electrode of the coupling capacitor part with an electric connection means. CONSTITUTION:A filter part F1 is formed with two input output vibration electrodes 4a, 4b formed to an upper face of the left side of a base 2 and with one common vibration electrode 5 formed to the lower side of the base 2 opposite to them. Similarly, a filter part F2 is formed with two input output vibration electrodes 6a, 6b formed to an upper face of the right side of the base 2 and with one common vibration electrode 7 formed to the lower side of the base 2 opposite to them. The vibration electrodes 4b, 6a of the filters F1, F2 are connected via a relay leadout electrode 8 and the vibration electrodes 5, 7 of the filters F1, F2 are connected via a relay leadout electrode 9. The coupling capacitor part C1 consists of capacitor electrodes 12a, 12b formed to lower and upper faces of the sealing base 11 and the required capacitance is obtained from a part where the electrodes 12a and 12b are opposite to each other. A dielectric material is used for the sealing bases 10, 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a piezoelectric filter with built-in capacitance.

As this type of chip-type piezoelectric filter, for example,
Energy trapping type two-stage coupling filter 7 shown in Fig. 3
0 is known. The piezoelectric substrate 71 has two multimode ◆ filter sections F11. F12 and one coupling capacitor CI
It is equipped with O. As this substrate 71, a piezoelectric ceramic substrate or the like is used. Input/output extraction electrode 72. 73 are formed at the left and right ends of the upper surface of the substrate 7l, and a common extraction electrode 74 is formed at the center of the lower side of the lower surface of the substrate 71.

The filter section Fil includes two input/output vibrating electrodes 75a. 75b and one common vibration electrode 76 formed on the lower surface of the substrate 71 opposite to these. Similarly, filter section F1
2 are two input/output vibration electrodes 78a on the upper right side of the substrate 71.
．． 78b and one common vibrating electrode 79 opposite to these
It consists of

The coupling capacitance section CIO is for coupling the filter sections Fil and F12, and is located between the filter sections Fil and FIZ, and includes capacitance electrodes 77a. 77b. These filter sections Fil, F12 and coupling capacitance section CIO are electrically connected by a conductor line. This substrate 71 and a sealing substrate stacked in the thickness direction are fixed with an adhesive to form a sealed vibration space. An insulating material is used for the sealing substrate.

The first equivalent electric circuit of the filter 70 having the above configuration is
415!0. Filter sections Fil and F12 are inserted in parallel between the input/output signal line and the common signal line with the coupling capacitance section C10 interposed therebetween.

By the way, in order to ensure the capacitance required for the coupling capacitance section CIO, the capacitance electrodes 77a. It is necessary to make the shape of 77b somewhat large. Therefore, the piezoelectric substrate 7
The size of 1 has become large, which has become an obstacle to miniaturizing parts. Further, if the region of the substrate 71 where the coupling capacitance portion CIO is formed is polarized, the capacitance electrode 77a. 7
When a signal voltage is applied to electrode 7b, electrodes 77a-77b
The portion of the substrate 71 sandwiched therebetween is mechanically excited by electrostriction. Therefore, the coupling capacitance section CIO acts as a vibrator, deteriorating the electrical characteristics of the filter 70. Therefore, as a countermeasure to this problem,
A method in which polarization is not applied only to the region where O is formed. ■ Capacitor electrode 77a of coupling capacitor section CIO. Methods such as applying damping treatment by mounding up solder or coating resin material on the surface of 77b are adopted. However, these methods require complicated operations, resulting in poor productivity and a resulting deterioration in yield.

Therefore, an object of the present invention is to provide a chip-type piezoelectric filter with built-in capacitance that does not require complicated manufacturing processes such as polarization processing and damping processing, and can be made smaller. In order to solve the problem that is more than a means for determining, the chip-type piezoelectric filter according to the present invention includes a piezoelectric substrate provided with a plurality of vibrating parts,
The sealing substrate stacked in the thickness direction of the piezoelectric substrate forms a sealed vibration space, and the coupling capacitor for coupling between the vibrating parts is made of a dielectric material. provided on a substrate, at least one of the capacitance electrodes of the coupling capacitance section is formed on the outer surface of the sealing substrate, and the vibrating electrode of the vibrating section and the capacitance electrode of the coupling capacitance section are connected by an electrical connection means. It is characterized by being In the above configuration, by changing the formation position of the coupling capacitance from the piezoelectric substrate to the sealing substrate, complicated operations such as polarization processing and damping processing of the piezoelectric substrate, which were conventionally performed, are no longer necessary. ．． Furthermore, the area where the capacitive electrode was formed can be omitted, the size of the piezoelectric substrate is reduced, and as a result, the size of the piezoelectric filter is also reduced. Below, embodiments of the chip-type piezoelectric filter according to the present invention will be described along with a method for manufacturing the same.

[First Embodiment] Fig. 1 shows an exploded perspective view of an energy trapping type two-stage coupling filter 1. This filter 1 is a chip-type filter that includes two filter sections and one coupling capacitance section. The piezoelectric substrate 2 has two multimode filter sections Fl.
, F2. Substrate 2 is Pb(ZrI'i)O
A piezoelectric ceramic substrate such as BaIiOs or BaIiOs is used. Input/output extraction electrode 3a. 3b are formed at the left and right ends of the upper surface of the substrate 2, and a common extraction electrode 9 is formed at the center of the lower side of the lower surface of the substrate 2.

The filter section F1 is composed of two input/output vibrating electrodes 4a and 4b formed on the upper left surface of the substrate 2, and one common vibrating electrode 5 formed on the lower surface of the substrate 2 in opposition to these electrodes. Similarly, the filter section F2 is composed of two input/output vibrating electrodes 6a*6b on the upper right side of the substrate 2 and one common vibrating electrode 7 opposed to these.

In the filter parts F1 and F2, the vibrating electrodes 4b and 68 are connected via a relay lead-out electrode 8, and the vibrating electrodes 5 and 7 are connected via a common lead-out electrode 9. The coupling capacitance portion C1 includes capacitance electrodes 12a. 12b, and the required capacitance is obtained at the portion where electrodes 12a and 12b face each other. A dielectric material is used for the sealing substrate 10.11.
However, the sealing substrate 10 is not limited to a dielectric material, and may be any insulating material.

In the actual mass production process, these substrates 2, 10, and 11 have a wide area, and are cut into predetermined dimensions after bonding.

The thus prepared substrates 2.10.11 are fixed with adhesive at a distance so as not to come into direct contact with each other,
Forms a sealed vibration space.

FIG. 2 shows the appearance of the filter 1. External input/output terminals (A
). (B) and an external common terminal (C) are formed. An input/output lead electrode 3a is connected to the input/output terminal (A), and an input/output lead electrode 3b is connected to the other input/output terminal (B).
is connected. A common lead electrode 9 and a capacitor electrode 12b are connected to the common terminal (C). Further, an external relay terminal (D) formed on the rear end face of the filter 1 is connected to a relay lead-out electrode 8 and a capacitor electrode 12a.

Filter 1 with the above configuration has the same electrical equivalent circuit as shown in FIG. Filter sections F1 and F2 are inserted in parallel between the input/output signal line and the common signal line with a coupling capacitance section C1 therebetween.

The filter 1 obtained in this way does not require the coupling capacitance section C1 on the piezoelectric substrate 2, so complicated operations such as polarization treatment and damping process are not required, improving productivity and yield. be done. Further, the area where the capacitive electrode was formed can be omitted, the size of the piezoelectric substrate 2 can be reduced, and as a result, the size of the filter 1 can also be reduced.

[Second Embodiment] FIG. 3 shows an energy trapping three-stage coupling filter 15.
An exploded perspective view is shown. This filter 15 is a chip type filter including three filter sections and two coupling capacitance sections. The piezoelectric substrate 16 is formed with three multimode filter sections Fl, F2, and F3. The sealing substrate 18 made of a dielectric material has two coupling capacitors CI. C
2 is formed. These substrates 16, 18 are fixed together with the insulator substrate 17 with an adhesive to form a sealed vibrating space. FIG. 4 shows the appearance of the filter 15. External input/output terminals (A) and (B) are formed at the left and right ends of the filter 15, respectively. Further, an external common terminal (C), an external relay terminal (Di) . (D2> is formed.

[Third Embodiment] FIG. 5 shows an energy trapping type two-stage coupling filter 20.
An exploded perspective view is shown. This filter 20 is a chip type filter that includes two filter sections and two coupling capacitance sections. The piezoelectric substrate 21 has two multimode filter sections Fl and F2 formed thereon. Filter part Fl
．． A shield conductor 24 is formed between F2 to prevent electrical coupling between filter parts F1 and F2. Sealing substrate 22. 23 each have a coupling capacitance portion Cl.
, C2 is formed. A dielectric material is used for the sealing substrates 22 and 23. FIG. 6 shows the appearance of the filter 20. External input/output terminals (A) and (B) are formed at the left and right ends of the filter 20, respectively. Furthermore, an external common terminal (C) and an external relay terminal (D) are formed on the front end surface and the rear end surface of the filter 20, respectively.

[Fourth embodiment] FIG. 7 shows an energy trapping type two-stage coupling filter 30.
An exploded perspective view is shown. This filter 30 is a chip type filter including two filter sections and two coupling capacitance sections. The piezoelectric substrate 31 has two multimode filter sections F1. F2 is formed.

A sealing substrate 32 made of this piezoelectric substrate 3l and a dielectric material
．． 33 are fixed with adhesive to form a sealed vibration space.

FIG. 8 shows the appearance of the filter 30. External input/output terminals (A), (
B), and an external common terminal (C) and an external relay terminal (D) are formed at the left and right ends of the rear side of the filter 30, respectively. Here, connect the external common terminal (C) and the external relay terminal (
D) is used as an electrode for attachment to a printed wiring board, etc., and also functions as a capacitive electrode. That is, the coupling capacitance portion C1 is formed in the portion of the sealing substrate 32 where the terminals (C) and (D) face each other, and the sealing substrate 33
Of these, terminal (C). A coupling capacitance portion c2 is formed in the portion where (D) faces. Therefore, there is no need to specially form a capacitor electrode on the sealing substrate.

[In the fifth embodiment, FIG. 9 shows an energy trapping type two-stage coupling filter 40.
An exploded perspective view is shown. This filter 40 is a chip type filter including two filter sections and one coupling capacitance section. The piezoelectric substrate 41 has two multimode filter sections Fl. F2 is formed.

Filter section F1. A shield conductor 44 is formed between F2 to prevent electrical coupling between filter parts F1 and F2. This piezoelectric substrate 41, a sealing substrate 42 made of a dielectric material, and a sealing substrate 43 made of an insulating material are fixed with an adhesive to form a sealed vibration space. FIG. 10 shows the appearance of the filter 40. External input/output terminals (A), (B) and an external common terminal (C) are formed at the left and right ends and the center of the filter 40 on the front side, respectively. The external common terminal (C) is extended to reach the inner end face of the filter 40. This terminal (C
) forms a coupling capacitance portion C1 between the capacitor electrode 45 connected to the external relay terminal (D). The capacitor electrode 45 is A
A conductive paste or the like of g is formed on the outer surface of the filter 40 by printing or other means.

[Sixth Embodiment FIG. 11 shows an energy trapping type two-stage coupling filter 5]
0 is shown in an exploded perspective view. This filter 50 is a chip type filter including two filter sections and one coupling capacitance section. The piezoelectric substrate 51 has two multimode filter sections Fl. F2 is formed. Filter part F1
A conductor 54 is provided at the center of the conductor path connecting between F2 and F2. The sealing substrate 52 made of a dielectric material has capacitive electrodes 55a . 55b is formed. These substrates 51 and 52 are fixed together with an insulating substrate 53 using an adhesive to form a sealed vibration space. At this time, the conductor 54 contacts the capacitive electrode 55b forming the coupling capacitance section C1, and the filter section F1. F2 and the coupling capacitance section C1 are electrically connected.

FIG. 12 shows the appearance of the filter 50. External input/output terminals (A) and (B) are formed at the left and right ends of the filter 50, respectively. Further, an external common terminal (C) is formed in a band shape in the center of the filter 50.

The filter 50 includes filter parts Fl and F2 and a coupling capacitance part C1.
Since electrical connection is made between the two via the conductor 54, no external relay terminal is required.

[Other Embodiments] The chip-type piezoelectric filter according to the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the gist.

From the viewpoint of productivity and yield, it is most preferable that the piezoelectric substrate be composed of a single piezoelectric substrate, but it may be composed of multiple layers depending on the case.

Furthermore, the shapes and layouts of the vibrating electrodes formed on the piezoelectric substrate, the capacitive electrodes formed on the sealing substrate, and the external terminals are not limited to those in the embodiment.

Furthermore, an auxiliary capacitor and other resistance elements and inductance elements may be additionally connected between the external terminals.

On the other hand, if the required capacitance cannot be obtained only with the capacitance of the coupling capacitance section formed on the sealing substrate, the capacitance may be formed on the piezoelectric substrate. In this case, although the piezoelectric substrate requires complicated operations such as polarization treatment and damping treatment, it is possible to reduce the size of the component.

Effects of the Invention In the present invention, by changing the formation position of the coupling capacitance portion from the piezoelectric substrate to the sealing substrate, complicated operations such as polarization treatment and damping treatment of the piezoelectric substrate are unnecessary. Therefore, a chip-type piezoelectric filter with a built-in capacitance is provided which improves productivity and yield.

In addition, the piezoelectric substrate can omit the area where the capacitive electrode is formed, and therefore, it is possible to respond to miniaturization of the component size.

Moreover, there is a high degree of freedom in designing the shape, layout, etc. of the capacitor electrode formed on the sealing substrate, and electrical characteristics can be improved and stabilized.

Furthermore, since the capacitor electrode is formed on the outer surface of the sealing substrate made of a dielectric material, the capacitance can be adjusted by cutting the capacitor electrode after the product is completed.

Furthermore, as in the case of the fourth embodiment, capacitance can be obtained without specifically forming a capacitor electrode on the sealing substrate, and the manufacturing process can be simplified.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a chip-type piezoelectric filter according to a first embodiment of the present invention, and FIG. 2 is a perspective view showing its appearance. 3 and 4 show the second embodiment, FIGS. 5 and 6 show the third embodiment, FIGS. 7 and 8 show the fourth embodiment, and FIGS. Figure 10 shows the fifth embodiment, Figure 11,
FIG. 12 shows a sixth embodiment, and is an exploded perspective view of a chip-type piezoelectric filter and a perspective view of its external appearance, respectively. 13 and 14 show a conventional chip-type piezoelectric filter, FIG. 13 is a plan view of a piezoelectric substrate, and FIG. 14 is an electrical equivalent circuit diagram thereof. 1... Chip type piezoelectric filter (energy trap type two-stage coupling filter), 2... Piezoelectric substrate, 4a. 4b
．． 5. 6a. 6b. 7... Vibrating electrode, 1
1-... Sealing substrate, 12a. 12b...capacitance electrode, 1
5... Chip type piezoelectric filter (energy confinement type three-stage coupling filter), 16... Piezoelectric substrate, 18...
- Sealing substrate, 20... Chip type piezoelectric filter (energy trap type two-stage coupling filter), 21... Piezoelectric substrate, 22. 23... Sealing substrate, 30... Chip type piezoelectric filter (energy trap type two-stage coupling filter), 31... Piezoelectric substrate, 32. 33... Sealing substrate, 40... Chip type piezoelectric filter (energy trap type two-stage coupling filter), 41... Piezoelectric substrate,
42... Sealing substrate, 50... Chip type piezoelectric filter (energy trap type two-stage coupling filter), 51...
・Piezoelectric substrate, 52... Sealing substrate, 55a, 55b
...Capacitive electrode, (A). (B), (C). (D), (
DI). (D2>...external terminal, C1.C2...coupling capacitance section, Fl, F2, F3...vibrating section (filter section).

Claims (1)

[Claims] 1. A piezoelectric substrate provided with a plurality of vibrating parts and a sealing substrate stacked in the thickness direction of the piezoelectric substrate form a sealed vibration space to couple the vibrating parts. A coupling capacitance section is provided on the sealing substrate made of a dielectric material, at least one of the capacitance electrodes of the coupling capacitance section is formed on the outer surface of the sealing substrate, and the vibration electrode of the vibration section and the coupling A chip-type piezoelectric filter characterized in that a capacitor electrode of a capacitor part is connected to the capacitor electrode by an electrical connection means.