JPH04233311A - Piezoelectric parts - Google Patents

Abstract

PURPOSE:To obtain the piezoelectric parts of a structure in which a damping material does not ooze out to the adhesion surface of a casing constituted of a case member and a cover member. CONSTITUTION:On an opening side of an inner wall of a case member 2, an intermediate stage 4 is provided, and a metallic thin film 5b of silver, etc., for functioning as an electrode is formed so as to intersect this intermediate stage 4. A piezoelectric body substrate 10 is contained in a recessed part 3 of the case member 2, and thereafter, by injecting molten silicon until it reaches the intermediate stage 4, a damping material 7 is formed. In such a case, the molten silicon oozes out to the part of the metallic thin film 5b formed on the surface of the intermediate stage 4 and forms an ooze-out part 7a, as the case may be, it does not occur that it oozes out to the adhesion surface 2e of the case member 2. Thereafter, a cover member 8 is attached fixedly to the case member 2 with an adhesive agent 14 of an epoxy compound, and the piezoelectric body substrate 10 becomes a state that it is contained in a vibration space closed tightly and completely by the case member 2 and the cover member 8.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to piezoelectric components used in audio IF circuits, demodulation circuits, trap circuits, and the like.

0002

2. Description of the Related Art Conventionally, as this type of piezoelectric component, one shown in FIG. 3 is known. The casing 20 is composed of a box member 21 and a lid member 26, and these box member 21 and lid member 26 are fixed together with an adhesive 25 interposed therebetween. This piezoelectric substrate 27 has a vibrating electrode on its surface.
It is housed in the casing 20 together with a damping material 28 covering the casing 7. An extraction electrode 22 made of a thin silver film formed on the surface of the box member 21 is connected to an extraction electrode extracted from the vibration electrode of the piezoelectric substrate 27.

In the piezoelectric component having the above structure, when the piezoelectric substrate 27 is covered with the damping material 28, when the molten damping material is injected into the box member 21, a part of the damping material seeps into the extraction electrode 22 and stains. A protruding portion 28a is formed. Since this seeping portion 28a is formed on the adhesive surface of the box member 21, the adhesion between the box member 21 and the lid member 26 becomes insufficient. This is because the adhesive strength between the epoxy resin adhesive, which is normally used as an adhesive, and the damping material (for example, silicone rubber) is weak.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a piezoelectric component having a structure in which the damping material does not seep into the adhesive surface of the casing.

[0005]

[Means for Solving the Problems] In order to solve the above problems, a piezoelectric component according to the present invention has a casing composed of a box member and a lid member, an intermediate stage is provided on the inner wall surface of the box member,
The piezoelectric substrate is characterized in that a damping material in a molten state is injected up to this intermediate stage position to cover the piezoelectric substrate.

[0006]

[Operation] In the above structure, the intermediate stage provided on the inner wall surface of the box member increases the creeping distance between the adhesive surface of the box member and the interface of the damping material. As a result, even if the damping material seeps out to the middle stage, it will not reach the adhesive surface of the box member.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a piezoelectric component according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of a piezoelectric component. The insulating casing 1 is composed of a box member 2 and a lid member 8. The box member 2 has a recess 3, and steps 2a, 2b, and 2c are provided at both ends and the center of the bottom of the recess 3 to horizontally support a piezoelectric substrate 10, which will be described later, in a laterally elongated state. An intermediate step 4 is provided around the opening side of the recess 3. Metal thin films 5a, 5b, 5c of silver or the like are formed on the steps 2a, 2b, 2c of the box member 2 by a method such as vapor deposition or sputtering. These thin films 5a to 5c
crosses the intermediate stage 4 and extends on the top, bottom and side surfaces of the box member 2.

The piezoelectric substrate 10 is made of BaTiO3 or Pb(
It consists of a ceramic substrate such as ZrTi)O3, and vibrating electrodes 12a, 12b, 12c, 12d, 12 are provided on the front and back surfaces of the substrate.
e and 12f are provided. This piezoelectric substrate 10 has lead electrodes 13a, 13d, 13e connected to vibrating electrodes 12a, 12d, 12e, 12f, respectively, and a thin film 5a.
, 5b, and 5c. After this, the molten silicone rubber etc. are poured into the recess 3 of the box member 2.
The liquid is injected into the middle stage 4 by a method such as a dispenser method. The silicone rubber also wraps around the back surface of the piezoelectric substrate 10, sufficiently covering the vibrating portion of the piezoelectric substrate 10. This silicone rubber solidifies and becomes a damping material 7 (see FIG. 2). At this time, a portion of the silicone rubber seeps into the metal thin films 5a, 5b, and 5c formed on the surface of the intermediate stage 4, forming a seeping portion 7a. However, due to the intermediate stage 4, the creepage distance between the adhesive surface 2e of the box member 2 and the interface of the damping material 7 is increased, so the damping material 7
The seeping portion 7a does not reach the adhesive surface 2e.

The lid member 8 has metal thin films 9a, 9b, and 9c formed on both ends and the center by a method such as vapor deposition. This lid member 8 is placed on the adhesive surface 2e of the box member 2 in which the piezoelectric substrate 10 is housed, and the adhesive 14 (see FIG. 2) previously applied to the adhesive surface 2e of the box member 2, such as epoxy It is fixed to the box member 2 with a type of adhesive. In this way, the piezoelectric substrate 10 is housed in a vibration space completely sealed by the box member 2 and the lid member 8. After this,
A thick metal film 15 (see FIG. 2) or the like is formed on the exposed portions of the thin metal films 5a, 5b, 5c, 9a, 9b, and 9c by means such as plating to obtain a finished product.

It should be noted that the piezoelectric component according to the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways within the scope of the gist. In particular, it is not necessary to provide the intermediate stage on the entire outer periphery of the concave portion of the box member, and even if it is provided only on the portion where the metal thin film is formed, it is possible to prevent the damping material from seeping into the adhesive surface.

[0011]

As described above, according to the present invention, since the intermediate stage is provided on the inner wall surface of the box member, the mutual creepage distance between the adhesive surface of the box member and the interface of the damping material is increased, and damping A piezoelectric component having a structure in which the material does not seep into the adhesive surface of the casing can be obtained. As a result, a highly sealed vibration space can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a piezoelectric component according to the present invention.

FIG. 2 is a vertical cross-sectional view taken along line X-X' in FIG. 1;

FIG. 3 is a vertical sectional view showing a conventional example.

[Explanation of symbols]

1... Casing 2... Box member 2e... Adhesive surface 3... Recessed portion 4... Intermediate stage 7... Damping material 7a... Seepage portion 8... Lid member 10... Piezoelectric substrate 12a, 12b, 12c, 12d, 12e, 12f... Vibrating electrode

Claims (1)

[Claims] 1. A piezoelectric component comprising a piezoelectric substrate provided with a vibrating electrode, a damping material covering the piezoelectric substrate, and a casing housing the piezoelectric substrate and the damping material, wherein the casing is a box member. and a lid member, an intermediate stage is provided on the inner wall surface of the box member, and the damping material in a molten state is injected up to the position of the intermediate stage to cover the piezoelectric substrate. .