JPH0534721U - Structure of piezoelectric chip parts - Google Patents

Abstract

(57) [Summary] [Object] The present invention prevents deterioration of electrical characteristics of a piezoelectric element by preventing the inner wall of the sealing cap and the vibrating portion of the piezoelectric substrate from approaching each other with a simple structure. An object of the present invention is to provide a structure of a piezoelectric chip component that can improve the yield rate. [Structure] The inner wall central portions 25a, 26a of the sealing cap 21 facing the vibrating portion 3a of the piezoelectric substrate 3 are more than the inner wall corner portions 25b, 26b of the cap 21 facing both end portions 3b, 3b of the piezoelectric substrate 3. The structure of the piezoelectric component is expanded in a direction away from the vibrating portion 3a. Even if the mutual positional relationship between the piezoelectric substrate 3 and the cap 21 is distorted, an inner wall corner of the cap 21 is formed. Part 25
Since b or 26b contacts both ends 3b, 3b of the piezoelectric substrate 3 and functions as a stopper, it is possible to prevent the vibrating portion 3a of the piezoelectric substrate 3 from approaching the inner wall of the cap, and the adhesive 20 causes the vibrating portion 3a. Can be prevented from adhering to.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a piezoelectric chip component used by being incorporated in various electronic circuits, and more particularly to a structure in which a thickness shear vibration resonator is covered with a sealing cap.

[0002]

[Prior Art]

 There is a tendency for electronic parts constituting various electronic circuits to be made into chips, and for example, piezoelectric parts used as reference oscillators of clock circuits are also desired to be made into chips.

FIG. 6 is a plan view showing a conventional sealing structure for a piezoelectric chip component, in which a thickness-shear vibration resonator having opposing electrodes 2a and 2b provided on both sides of a rectangular piezoelectric substrate 3 has a base substrate 4 as a base plate. The lead-out electrodes 5 and 6 are connected by the conductive pastes 7 and 8, and the sealing cap (FIG. 7) is adhered to the insulating adhesive 9 that is patterned in the shape of a rectangular frame.

[0004]

[Problems to be solved by the device]

 However, in the structure of the conventional sealing cap described above, as shown in FIG. 7, since the inner walls 10a, 10a along both sides of the piezoelectric substrate 3 are flat surfaces, the vibrating portion 3a of the piezoelectric substrate 3 is As shown in FIG. 8, the adhesive 9 of the cap 10 may adhere to the vibrating portion 3a due to the approach of the one inner wall 10a or the approach of the both 3a, 10a. Therefore, there is a drawback that vibration of the piezoelectric substrate 3 is damped by the cap 10 and electrical characteristics are deteriorated.

In order to prevent this, it is necessary to closely manage the mutual positional relationship between the chip components 3, 4 and 10, which inevitably leads to a decrease in assembly performance. Moreover, as the adhesive 9, a thermosetting adhesive such as an epoxy resin is often used, and therefore, the displacement of the cap 10 and the exudation of the adhesive 9 are prevented before the adhesive is cured. Occurrence is unavoidable, and there is a limit to the management of the positional relationship.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is possible to prevent the inner wall of the sealing cap and the vibrating portion of the piezoelectric substrate from approaching each other with a simple structure. It is an object of the present invention to provide a structure of a piezoelectric chip component capable of preventing deterioration of electric characteristics of a substrate and improving a non-defective rate.

[0007]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention is a piezoelectric device in which both ends of a piezoelectric substrate are connected to a lead-out electrode formed on a base substrate with a conductive paste and the piezoelectric substrate is covered with a sealing cap. In the structure of the chip part, the central portion of the inner wall of the sealing cap facing the vibrating portion of the piezoelectric substrate bulges away from the vibrating portion more than the inner wall corners of the cap facing both ends of the piezoelectric substrate. It is characterized by

[0008]

[Action]

 According to this invention, since the central portion of the inner wall of the sealing cap facing the vibrating portion of the piezoelectric substrate is bulged in the direction away from the vibrating portion, the mutual position of the piezoelectric substrate and the sealing cap is temporarily assumed. Even if the relationship is changed, the inner wall corners of the cap contact the both ends of the piezoelectric substrate and function as stoppers. Therefore, it is possible to prevent the vibrating portion of the piezoelectric substrate from approaching the central portion of the inner wall of the cap, and there is no fear that the adhesive agent of the cap is attached to the vibrating portion.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, both ends 3b, 3b of the piezoelectric substrate 3 are bonded onto the electrode parts 5, 6 of the alumina base substrate 4 by conductive pastes 7, 8. This structure is the same as the conventional one, and the corresponding parts are designated by the same reference numerals.

Reference numeral 20 denotes an insulating adhesive, which is pattern-coated in a substantially rectangular frame shape on the base substrate 4 in conformity with the side wall shape of the sealing cap 21 made of alumina according to the present invention. As shown in FIG. 3, the cap 21 includes a top plate portion 22, end walls 23 and 24, and side walls 25 and 26. The inner wall surfaces of the side walls 25 and 26 are curved in an arc shape so that the inner wall center portions 25a and 26a bulge outward from the inner wall corner portions 25b and 26b by a predetermined dimension t and at the inner wall center portions. The portions 25a and 26a face the vibrating portion 3a (FIG. 1) of the piezoelectric substrate 3, and the inner wall corner portions 25b and 26b face both ends 3b and 3b (FIG. 1) of the piezoelectric substrate 3.

Here, as shown in FIG. 4, the bulging width t is the vibrating portion 3a when both end portions 3b and 3b of the piezoelectric substrate 3 are in contact with the inner wall corner portions 25b and 25b of the cap 21, respectively. And a sufficient gap G is formed between the inner wall central portion 25a (or 26a) and the adhesive 20 of the cap 21 is set to a size that does not adhere to the vibrating portion 3a.

According to the above configuration, as shown in FIG. 4, even if the mutual positional relationship between the piezoelectric substrate 3 and the sealing cap 21 is incorrect, the inner wall corner portion 25b of the cap 21 may be misaligned. , 25b come into contact with both ends 3b, 3b of the piezoelectric substrate 3 to function as stoppers. Therefore, it is possible to prevent the vibrating portion 3a of the piezoelectric substrate 3 from approaching the inner wall of the cap, and there is no fear that the adhesive 20 adheres to the vibrating portion 3b. As a result, the vibration of the vibrating portion 3a is not damped by the cap 21, and the deterioration of the electrical characteristics of the thickness shear vibration resonator can be prevented.

Further, since it is not necessary to precisely manage the positional relationship between the chip components (the base substrate 4, the piezoelectric substrate 3, the cap 21), it is possible to improve the assembling performance and improve the yield rate.

In the above embodiment, the inner surface of the side wall of the cap 21 is formed in an arc shape, and the bulging width t of the inner wall central portion 25a (or 26a) with respect to the inner wall corner portions 25b, 25b (or 26b, 26b) is set. However, as shown in FIGS. 5A to 5D, the side walls of the caps 21a to 21d are formed in various shapes to form the bulging width t of the inner wall central portion B with respect to the inner wall corner portion A. You may do it.

[0016]

[Effect of the device]

 As described above, according to the present invention, it is possible to prevent the central portion of the inner wall of the sealing cap and the vibrating portion of the piezoelectric substrate from approaching each other, and prevent the adhesive from adhering to the vibrating portion. As a result, the deterioration of the electrical characteristics of the piezoelectric element can be prevented, and as a result, the yield rate can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a sealing structure of a thickness shear vibration resonator according to the present invention.

FIG. 2 is a central sectional view of FIG.

FIG. 3 is a bottom perspective view of a sealing cap.

FIG. 4 is a partially cutaway plan view showing a state where the piezoelectric substrate and the sealing cap are displaced from each other.

FIG. 5 is a schematic view showing a modified example of the sealing cap.

FIG. 6 is a plan view showing a conventional sealing structure for a thickness shear vibration resonator.

FIG. 7 is a partially cutaway plan view showing a state where a conventional piezoelectric substrate and a sealing cap are displaced from each other.

FIG. 8 is a central sectional view of FIG.

[Explanation of symbols]

 3 Piezoelectric substrate 4 Base substrate 20 Adhesive 21 Sealing cap 25,26 Side walls 25a, 26a Inner wall central part 25b, 26b Inner wall corner part t Swelling width

Claims (1)

[Scope of utility model registration request] 1. A structure of a piezoelectric chip component in which both ends of a piezoelectric substrate are connected to a lead-out electrode formed on a base substrate with a conductive paste, and the piezoelectric substrate is covered with a sealing cap. A piezoelectric body characterized in that a central portion of the inner wall of the sealing cap facing the vibrating portion of the substrate bulges away from the vibrating portion more than the inner wall corner portions of the cap facing both ends of the piezoelectric substrate. Structure of chip parts.