JPH02309707A - Manufacture of piezoelectric resonance component - Google Patents

Abstract

PURPOSE:To manufacture a protection substrate at low cost with high accuracy by providing a process for sandwiching and uniting a piezoelectric resonance element between a couple of insulating plates so that a space is formed of a recessed part in the vibration area of the piezoelectric element. CONSTITUTION:A resist film 22 is formed on one main surface of an insulating plate 21. The resist film 22 is formed covering an area except of a center area 21a of specific size. The area 21a is set so as to form the recessed part for preventing the vibration of the vibration area of the piezoelectric resonance element from being disturbed. Then the plate is etched by using an etching material from the main surface side which is not covered with the resist film 22 to form the recessed part 23 in the insulating plate 21. Any etching agent is usable as long as the insulating plate 21 is etched.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing piezoelectric resonant components such as piezoelectric resonant devices and filters, and in particular, a process for obtaining a structure that seals the main part of a piezoelectric resonant element. relates to an improved method.

[Conventional technology]

FIG. 2 shows an example of a conventional piezoelectric resonant component.

In the piezoelectric resonant component 1, electrodes 3 and 4 are formed on both main surfaces of the piezoelectric plate 2 so as to partially face each other, thereby forming a piezoelectric resonant element. This piezoelectric resonant element is sandwiched between and integrated with protective substrates 5.6 made of an insulating material arranged above and below.

Protective group Fi5.6 is provided with recesses 5a and 6a, respectively. The recesses 5a and 6a are provided to expose the overlapping region of the electrodes 3 and 4, that is, the vibration region, so as not to hinder vibration in the vibration region. Note that 7.8 indicates external electrodes, and electrodes 3.8 and 7.8 indicate external electrodes, respectively.
It is electrically connected to 4.

When manufacturing the piezoelectric resonant component 1, an 8W substrate 5.6 and a piezoelectric resonant element 9, which are shown in an exploded perspective view in FIG.
Prepare.

The piezoelectric resonant element 9 has partial electrodes forming electrodes 3 and 4 (FIG. 2) on both main surfaces of a ceramic plate obtained by firing a ceramic material such as lead zirconate titanate.
This is obtained by applying a conductive paint to the entire rear main surface, polarizing it using a full-surface electrode made of the conductive paint, and finally etching it using an appropriate etchant so as to leave an excitation electrode 3°4. It will be done.

On the other hand, when forming the protective substrates 5 and 6, a rectangular ceramic green sheet is prepared, and a recess 6a (the recess 5a on the protective substrate 5 side is not shown in FIG. 3) is pressed into the two ceramic green sheets. Next, the protective substrates 5 and 6 are obtained by firing each ceramic green sheet.

The protective substrate 5.6 and the piezoelectric resonant element 9 prepared as described above are laminated with an adhesive in the direction shown in FIG. l was being manufactured.

As another method, a method using protective substrates 13 and 14 shown in FIG. 4 has been adopted in order to form a region that does not impede vibration as described above. Here, the protective substrate 13.
Four parts 14a (not shown on the protective substrate 13 side) are formed on the ceramic green sheet 14 by the same pressing operation in the state of the ceramic green sheet before firing. Then, by laminating and bonding together with the piezoelectric resonant element 9 in the direction shown in FIG. 4, a piezoelectric resonant component provided with a recessed portion was obtained as in the conventional example shown in FIG.

(Technical Problems to be Solved by the Invention) In any of the above-mentioned conventional methods, recesses are formed by pressing or the like in the ceramic green sheet before firing.By the way, the formation of such recesses is Usually, a large mother ceramic green sheet is prepared, a plurality of recesses are formed by pressing, etc., and then cut.

Therefore, since a large number of recesses are formed in alignment in the ceramic green sheet before firing, which does not have sufficient shape retention, the positions at which the recesses are formed tend to be misaligned. As a result, the vibrating electrode and the recess may not overlap with each other accurately, which may cause vibration damping.

Further, even if the recesses are formed in the mother ceramic green sheet with high precision, deformation tends to occur during firing, and ultimately it is still difficult to form the recesses with high precision. Therefore, the yield was not sufficient, which was a major factor in increasing costs.

Furthermore, when the shape of the vibrating electrode pattern of the piezoelectric resonant element becomes complicated, the above-mentioned recess forming method requires a new mold, which is difficult to handle.

An object of the present invention is to provide a method for manufacturing a piezoelectric resonant component that includes a process for manufacturing a protective substrate with higher precision and at a lower cost.

[Means for solving technical problems]

In the method for manufacturing a piezoelectric resonant component of the present invention, first, a resist film is coated on one main surface of an insulating plate except for a predetermined area. Etching is performed on the surface using an etching agent that corrodes the insulating plate to form recesses.

On the other hand, a piezoelectric resonant element having a piezoelectric plate and vibrating electrodes formed on both main surfaces of the piezoelectric plate is prepared.

Then, the piezoelectric resonant element is sandwiched and integrated between the pair of insulating plates so that a space is provided above the vibration region of the piezoelectric resonant element by the recess of the insulating plate.

[Effect]

Protective substrates, which are placed above and below the piezoelectric resonant element and provide a space in which the vibration region is exposed, are formed by etching an insulating plate. Therefore, the recesses are formed in an insulating plate with excellent shape retention.
After that, no treatment such as firing that induces deformation is performed.

In other words, the present invention makes it possible to form the recesses as late as possible in the process by forming the recesses by etching, thereby making it possible to form the recesses with high precision, and also to form the recesses in complex shapes. The feature is that it is easy to form a concave portion suitable for an electrode pattern.

[Explanation of Examples]

Hereinafter, a manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.

First, as shown in FIG. 1(a), an insulating plate 21 having a rectangular planar shape is prepared. The insulating plate 21 is
For example, it is made of an insulating material such as insulating ceramics such as alumina, piezoelectric ceramics, or glass.

Next, a resist film 22 is applied on one main surface of the insulating plate 21. The resist film 22 is applied so as to cover the remaining area except for the central area 21a having a predetermined width. The region 21a is set to form a recessed portion for not inhibiting vibration in a vibration region of a piezoelectric resonant element, which will be described later.

Further, the resist film 22 is mainly composed of a suitable resin material that is not corroded by an etching agent to be described later.

Next, the main surface covered with the resist film 22 is etched using an etching agent to form the four parts 23 shown in FIG. 1(b) on the insulating plate 1-21. As the etching agent, any suitable material can be used as long as it corrodes the insulating plate 21. For example, if the insulating plate 21 is made of alumina, hot concentrated sulfuric acid may be used as the etching agent.

After etching, the resist film 22 described above is removed using an appropriate solvent (FIG. 1(b) shows the removed state).

On the other hand, apart from the insulating plate 21, a piezoelectric resonant element 24 shown in FIG. 5 is prepared. The piezoelectric resonant element 24 has a structure in which electrodes 26 and 27 are formed on both main surfaces of a piezoelectric plate 25. ! Fii 26.27 includes vibration region parts 26a and 27a and a drawer part 26b, which face each other with the piezoelectric plate 25 in between.
27b.

Next, as shown in FIG. 6, insulating plates 21.21 each having a recess 23 formed therein are laminated above and below the piezoelectric resonant element 24. When stacking, the electrodes 26.2 are placed in the four parts 23.
Each insulating plate 21.degree. 21 is arranged in such a direction that the vibration region portions 26a and 27a of No. 7 are exposed.

When laminating the above layers, by interposing an appropriate adhesive (not shown), the resonant element 24 and the insulating plate 2
1.21 can be integrated. Thereafter, as shown in FIG. 7, a piezoelectric resonant component 30 can be obtained by applying external electrodes 28 and 29 to opposite end surfaces of the laminate.

The external electrodes 28, 29 can be formed by known methods such as baking, plating, or vapor deposition.

In the above embodiment, the recesses 23 are formed by etching, and high-temperature treatment such as firing is not performed in the steps subsequent to the step in which the recesses 23 are formed.Therefore, deformation of the recesses 23 is extremely unlikely to occur in subsequent steps.

Moreover, even when forming the recess 23 itself, since the insulating play 21 has shape retention properties, the recess 23 can be formed with high precision. Therefore, the yield can be improved and the cost of piezoelectric resonant components can be effectively reduced.

Note that, as shown in FIG. 8, normally a mother insulating plate 31 is prepared, and a plurality of recesses 23 are formed in alignment on one main surface thereof. Thereafter, individual piezoelectric vibrating components are obtained by laminating and adhering to the mother piezoelectric substrate and cutting. Even in this case, the mother insulation play) 3
1 has shape-retaining properties, the large number of recesses 23 can be formed in alignment with high precision.

In the embodiment described above, the substantially circular recess 23 was formed in the insulating plate 21. However, in the present invention, the recess formed in the insulating plate is not limited to having a substantially circular planar shape.

For example, in a piezoelectric resonant component such as a piezoelectric filter that has multiple vibration regions, a recess 32 having a complicated planar shape is formed in the insulating plate 21, as shown in FIG. 9(a). Good too.

Furthermore, as shown in FIG. 9(b), a recess 34 having protrusions 33, 33 for placing the piezoelectric resonant element may be formed. In this case, the upper surface of the protrusions 33 is etched. After that, the area between the protrusions 33 may be further etched.

In addition, as shown in FIG. 10, the recesses 35 and 36 have different planar shapes depending on the shape of the vibrating electrode pattern of the piezoelectric element.
may be formed on a single insulating plate 21, or as shown in FIG. Good too.

〔Effect of the invention〕

As described above, in the present invention, a recessed portion for exposing a vibration region is formed in an insulating plate by etching. Therefore, since the recesses are formed in the shape-retaining insulating plate, the recesses can be formed with high precision, and there is very little risk of deformation in subsequent steps. Compared to the case where the recesses are formed in a green sheet state, the accuracy of forming the recesses is dramatically improved, and therefore the yield can be improved.

Furthermore, since there is no need to prepare a mold or the like depending on the shape of the recessed portion, it is possible to effectively reduce the cost of the piezoelectric resonant component in conjunction with an improvement in yield.

Furthermore, since the recesses are formed by etching, it is not only easy to change the shape of the recesses, but also to easily form recesses with various complex planar shapes or three-dimensional shapes.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are perspective views showing a state in which a resist film is applied to an insulating plate and a state in which it is etched, respectively, in one embodiment of the present invention, and FIG. 2 is a perspective view of a conventional piezoelectric plate. A cross-sectional view of the resonant component, FIG. 3 is a perspective view for explaining the process of manufacturing the piezoelectric resonant component shown in FIG. 2, and FIG. 4 is an exploded perspective view for explaining another method of manufacturing the conventional piezoelectric resonant component. 5 is a perspective view showing a piezoelectric resonant element used in one embodiment of the present invention, and FIG. 6 is a perspective view showing a process of laminating a piezoelectric resonant element and an insulating plate in an embodiment of the present invention. FIG. 7 is an exploded perspective view, FIG. 7 is a sectional view of a piezoelectric resonant component obtained by a manufacturing method according to an embodiment of the present invention, FIG. 8 is a perspective view showing a state in which a recess is formed in the mother insulating plate, and FIG. Figures (a) and (b) are perspective views for explaining other examples of the shape of the recess, FIG. 1O is a perspective view for explaining still another example of the shape of the recess, and FIG. FIG. 3 is a perspective view showing an insulating plate with a processed outer surface. In the figure, 21 is an insulating plate, 21a is a predetermined region, 22 is a resist film, 23 is a recess, 24 is a piezoelectric resonant element, 25 is a piezoelectric plate, 26.27 is an electrode, 26a, 27a
is the vibration part, 31 is the mother insulating plate, 32, 34
, 35 and 36 indicate recesses. 6α Fig. 4 1Li-α

Claims (1)

[Claims] A step of preparing an insulating plate, a step of coating one principal surface of the insulating plate with a resist film except for a predetermined region, and a step of coating the insulating plate with the resist film. On the main surface,
A step of etching the insulating plate using an etching agent that corrodes the insulating plate to form a recess; and a step of preparing a piezoelectric resonant element having a piezoelectric plate and vibrating electrodes formed on both main surfaces of the piezoelectric plate. , a step of sandwiching and integrating the piezoelectric resonant element between the pair of insulating plates so as to provide a space by the recess above the vibration region of the piezoelectric resonator. How the parts are manufactured.