JPH0529868A - Piezoelectric resonator and its production - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric resonator with structure where a resin piece separated from a resin for armoring is hard to stick on a vibrating part. CONSTITUTION:Resin component 9 and 8 for forming voids 9 and 8 which respectively have openings 12 and 13 between themselves and the vibrating parts of vibration electrodes 2 and 3 on the surface and back faces of a piezoelectric body substrate 1 provided with the vibration electrodes 2 and 3 on the surface and back faces. Next, paraffin 21 is applied on parts(two parts) corresponding to the vibration parts at the end faces of the piezoelectric body substrate 1 so as to coat them by the resin for armoring. Moreover, the resin for armoring is hardened and also paraffin 21 is hot-deep coated and evaporated so as to be absorbed by the resin for armoring and, then, armor component 25 having vibration space in the inner part of the same is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric resonator used in an oscillation circuit, a filter circuit, etc. and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as this type of piezoelectric resonator, a thickness-shear vibration resonator shown in FIG. 6 has been known.
In this resonator, vibrating electrodes 32 and 33 are provided on the front and back surfaces of the piezoelectric substrate 31, and metal lead terminals 35 and 36 are electrically connected and fixed to the lead-out portions of the vibrating electrodes 32 and 33 with solder 37. , The periphery of the central portion corresponding to the vibrating portion of the resonator is covered with paraffin 39, further covered with the exterior resin 40, and then placed in a high temperature furnace to be heated to cure the exterior resin 40 and melt the paraffin 39. It is manufactured by being evaporated and absorbed by the exterior resin 40. This manufacturing method has good workability, is inexpensive, is suitable for mass production, and is widely applied.

By the way, when the resonator is covered with the exterior resin 40, air bubbles 42 may be caught in the exterior resin 40. In this case, the bubbles 42 may expand and burst during the process in which the paraffin 39 is absorbed by the exterior resin 40 by heating, and the resin piece 44 may drop onto the paraffin 39 (see FIG. 7). A part of the molten paraffin 39 is evaporated and absorbed by the exterior resin 40, while the rest is collected in the center of the resonator due to surface tension. Then, all the paraffin 39 is absorbed by the exterior resin 40, and the resin piece 44 remains on the vibrating electrode 32 at the center of the resonator (see FIG. 8). This resin piece 4
Since 4 acts as a load on the vibrating electrode 32, the electrical characteristics of the resonator are deteriorated.

Therefore, an object of the present invention is to provide a piezoelectric resonator having a structure in which the resin piece separated from the exterior resin is unlikely to adhere to the vibrating portion, and a method for manufacturing the same.

[0005]

In order to solve the above problems, a piezoelectric resonator according to the present invention comprises (a) a piezoelectric substrate provided with a vibrating electrode, and (b) a vibrating electrode. A cavity forming resin member having a gap between the cavity forming resin member and the vibrating portion of the vibrating electrode, and (c) covering the piezoelectric substrate and forming a vibration space together with the cavity forming resin member. And an exterior member to be formed.

In the above structure, since the cavity forming resin member is arranged with a gap between the cavity forming resin member and the vibrating portion of the vibrating electrode, the vibrating electrode vibrating portion is formed when the exterior member is formed. It is in a state of being covered with the cavity forming resin member. Therefore, the resin piece does not adhere to the vibrating portion of the vibrating electrode even if the air bubbles entrapped in the exterior resin burst due to heating.

Further, the method of manufacturing a piezoelectric resonator according to the present invention comprises: (d) applying a resist material to the vibrating portion of the vibrating electrode provided on the piezoelectric substrate; and (e) removing the resist material from the resist material. A step of covering with a cavity forming resin material leaving an opening for use, and (f) removing the resist material applied to the piezoelectric substrate to form a gap between the cavity forming resin material and the vibrating portion of the vibrating electrode. And (g) coating the piezoelectric substrate with an exterior resin material and forming a vibration space together with the cavity forming resin material.

According to the above method, after the resist material and the cavity-forming resin material are overcoated, only by removing the resist material, a gap is easily formed between the cavity-forming resin material and the vibrating portion of the vibrating electrode. It

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a piezoelectric resonator and a method of manufacturing the same according to the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, electrodes 2 and 3 to be oscillating electrodes are provided on the front and back surfaces of a mother substrate-shaped piezoelectric substrate 1 by means such as silver vapor deposition. As the piezoelectric substrate 1, a PbTiO ₃ or PLZT ceramic substrate or the like is used. Next, as shown in FIG.
Resist resins 5 and 6 are applied to the portions of the electrodes 2 and 3 to be the vibrating portions and the peripheral portions thereof by means of screen printing or the like and dried. As the resist resins 5 and 6, pastes of a heat-plasticizing resin which is easily dissolved in a solvent are used.

Next, as shown in FIG. 3, a thermosetting epoxy resin or the like is printed on the resist resins 5 and 6 by means of screen printing or the like and then heated and cured to form a cavity forming resin member. 8 and 9 are formed. At this time, even if air bubbles are caught in the epoxy resin and the air bubbles expand and burst due to heating, the resist resins 5 and 6 have already been applied to the vibrating portions of the electrodes 2 and 3. The resin piece separated from does not adhere to the vibrating portions of the electrodes 2 and 3. After forming the cavity forming resin members 8 and 9 in this way, the piezoelectric substrate 1 is cut out along the cutting line 11 with a predetermined width to form the piezoelectric resonator 15. In the cut-out piezoelectric resonator 15, the resist resins 5 and 6 are exposed on the cut-out surface. Therefore, the exposed surfaces of the resist resins 5 and 6 serve as openings for removing the resist resin, and the piezoelectric resonator 15
When is immersed in a solvent such as thinner, the resist resin 5,
6 begins to dissolve from the exposed surface. At this time, since the cavity forming resin members 8 and 9 have solvent resistance, there is no change. After the resist resins 5 and 6 are completely dissolved in the solvent, the piezoelectric resonator 15 is pulled up from the solvent. The solvent filled between the cavity forming resin members 8 and 9 and the vibrating electrodes 2 and 3 evaporates, and voids 12 and 13 are formed in those portions.

In the obtained piezoelectric resonator 15, as shown in FIGS. 4 and 5, lead terminals 18 and 19 are electrically connected and fixed to the vibrating electrodes 2 and 3, respectively, with solder 20. Next, after applying paraffin (or wax or the like) 21 to the portions (two places) corresponding to the vibrating portion on the end surface of the piezoelectric substrate 15 of the piezoelectric resonator 15, after covering it with the exterior resin, it is placed in a high temperature furnace. The paraffin (or wax, etc.) 21
Is melted and evaporated to be absorbed by the exterior resin. At this time, due to the viscosity of the exterior resin, the exterior resin has a gap 12,
Although it does not easily enter the space 13, a complete vibration space can be obtained by sealing the openings of the voids 12 and 13 with paraffin (or wax) 21.

Thus, the piezoelectric resonator 15 covered with the exterior member 25 is completed. The exterior member 25 forms a vibration space together with the cavity forming resin members 8 and 9. in this case,
The cavity forming resin members 8 and 9 have already been hardened and cover the vibrating portions of the vibrating electrodes 2 and 3 with the gaps 12 and 13 secured. Therefore, even if the air bubbles entrapped in the exterior resin expand and burst due to heating, the resin pieces separated from the exterior resin do not adhere to the vibrating electrodes 2 and 3. On the other hand, in the process where the paraffin applied to the end surface is absorbed by the exterior resin, bubbles trapped in the exterior resin may expand and burst due to heating, and the resin piece may adhere to the vibrating portion on the end surface of the piezoelectric substrate. However, compared to the case where the vibrating electrode is attached to the vibrating portion, the influence on the electrical characteristics is significantly small, and the failure occurrence rate due to the resin piece attachment is small.

Therefore, among the two types of electric characteristic measurement of the piezoelectric resonator at room temperature and at high temperature (about 80 to 100 ° C.), which have been conventionally performed to find out a defect due to the adhesion of the ruptured resin piece, All that is needed is to measure the electrical characteristics at room temperature. The piezoelectric resonator according to the present invention and the method for manufacturing the same are not limited to the above-described embodiments, but can be variously modified within the scope of the gist thereof. In particular,
The piezoelectric resonator may utilize vibration other than the thickness shear vibration, for example, thickness longitudinal vibration.

[0014]

As is apparent from the above description, according to the present invention, the exterior member is formed after the void is formed in the portion facing the vibrating portion of the vibrating electrode by the cavity forming resin member in advance, and thus the vibration is generated. A piezoelectric resonator having a structure in which a resin piece separated from the exterior resin does not easily adhere to the portion can be obtained. As a result, the rate of occurrence of defects due to resin piece adhesion is suppressed.

Further, in the method of manufacturing a piezoelectric resonator according to the present invention, the resist material applied to the vibrating portion of the vibrating electrode is coated with the cavity forming resin material leaving the resist material removing opening, and then the resist material is formed. Is removed to form a gap between the cavity forming resin material and the vibrating part of the vibrating electrode, so a piezoelectric resonator with a structure in which the resin piece separated from the exterior resin does not easily adhere to the vibrating part is simple. Can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a method of manufacturing a piezoelectric resonator according to the present invention.

FIG. 2 is a perspective view showing an embodiment of a method for manufacturing a piezoelectric resonator according to the present invention.

FIG. 3 is a perspective view showing an embodiment of a method of manufacturing a piezoelectric resonator according to the present invention.

FIG. 4 is a perspective view showing an embodiment of the piezoelectric resonator according to the present invention.

5 is a horizontal sectional view of the piezoelectric resonator shown in FIG.

FIG. 6 is a horizontal sectional view showing a conventional example.

FIG. 7 is a partial horizontal cross-sectional view for explaining a process in which a resin piece from the exterior resin is attached to the vibrating portion.

FIG. 8 is a partial horizontal cross-sectional view for explaining a process in which a resin piece from the exterior resin adheres to the vibrating portion.

[Explanation of symbols]

1 ... Piezoelectric substrate 2, 3 ... Vibration electrode 5, 6 ... resist resin 8, 9 ... Cavity forming resin member 12, 13 ... Void 15 ... Piezoelectric resonator 21 ... Paraffin 25 ... Exterior member

Claims (2)

[Claims] 1. A piezoelectric substrate provided with a vibrating electrode, a cavity forming resin member provided on a surface provided with the vibrating electrode and having a gap between the vibrating portion of the vibrating electrode, and the piezoelectric body. A piezoelectric resonator, comprising: an exterior member that covers a substrate and forms a vibration space together with the cavity forming resin member. 2. A step of applying a resist material to a vibrating part of a vibrating electrode provided on a piezoelectric substrate; a step of coating the resist material with a cavity forming resin material leaving a resist material removing opening. Removing the resist material applied to the piezoelectric substrate to form a gap between the cavity forming resin material and the vibrating portion of the vibrating electrode; and covering the piezoelectric substrate with an exterior resin material, and A step of forming a vibration space together with the cavity forming resin material, and a method of manufacturing a piezoelectric resonator.