JPH0865086A - Structure of package type piezoelectric oscillator - Google Patents

Abstract

PURPOSE: To reduce the stress due to a thermal distortion by fixing the electrodes at the both ends of a piezoelectric element to the electrode film for element which is formed on the internal bottom surface in the both ends part within a groove type recessed portion with conductive adhesive. CONSTITUTION: A piezoelectric element 13 is composed of a bar-shaped ceramic piece 13a, a lower surface side electrode film 13b formed so that it may be extended from one end toward the other end on the lower surface of this ceramic piece 13a and an upper surface side electrode film 13c formed so that it may be extended from the other end to the one end on the upper surface of the ceramic piece 13a. This piezoelectric element 13 is inserted within the groove type recessed portion 12 in a package body 11, the one end part of the lower surface side electrode film 13b is fixed to the one electrode 14 for the element in the groove type recessed portion 12 with thermoplastic synthetic resin system conductive adhesive 20, and the other end part of the upper surface side electrode film 13c is fixed to the other electrode film 15 for the element in the groove type recessed portion 12 with conductive adhesive 21 in the same way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a piezoelectric oscillator in which a piezoelectric element such as a piezoelectric ceramic element is packaged in a package body made of an insulating material such as synthetic resin.

[0002]

2. Description of the Related Art Conventionally, a package type piezoelectric oscillator of this type has a chip made of an insulating material such as a synthetic resin as disclosed in FIGS. 8 and 9 of Japanese Patent Application Laid-Open No. 2-105710. In the groove-shaped recess formed in the upper surface of the package body formed in the mold, the piezoelectric element, the electrode film at both ends of the piezoelectric element to the element electrode film formed on the inner surface at both ends in the groove-shaped recess While fixing with a conductive adhesive so as to electrically connect with each other, a lid plate made of an insulator is provided on the upper surface of the package body so that the lid plate seals the groove-shaped recess of the package. It is configured to stick.

[0003]

However, in the conventional package type piezoelectric oscillator described above, despite the large thermal expansion difference between the package body and the piezoelectric element mounted inside the package body, Since both ends of the piezoelectric element are fixed to the element electrode films at both ends in the groove-shaped recess of the package body, a conductive adhesive made of thermosetting synthetic resin such as epoxy resin is used. When a package-type piezoelectric oscillator is subjected to a heat load during soldering to a printed circuit board or the like, a crack is generated at a location of the conductive adhesive due to a difference in thermal expansion between the package body and the cover plate. In addition to the occurrence of the stress, there is a problem that the stress is generated in the piezoelectric element due to thermal strain and the characteristics thereof are deteriorated.

The present invention has an object of providing a structure capable of solving this problem.

[0005]

In order to achieve this technical object, the present invention provides: "A piezoelectric element is provided in a groove-shaped recess formed in the upper surface of an insulating material package and electrodes at both ends of the piezoelectric element. Is fixed to the electrode film for elements formed on the inner bottom surface at both ends in the groove-shaped recess so as to be electrically connected thereto, while a lid plate is fixed to the upper surface of the package body. In, the electrodes at both ends of the piezoelectric element are fixed to the element electrode film formed on the inner bottom surface at both ends in the groove-shaped recess with a thermoplastic synthetic resin-based conductive adhesive or are softened. It is fixed with a conductive synthetic resin-based conductive adhesive. "

[0006]

[Operation] In this way, by fixing the electrodes at both ends of the piezoelectric element to the element electrode film formed on the inner bottom surface at both ends in the groove-shaped recess, a thermoplastic synthetic resin-based conductive adhesive is used. When this agent is used, this thermoplastic synthetic resin-based conductive adhesive softens when subjected to a heat load and absorbs the difference in thermal expansion between the package body and the piezoelectric element fixed inside the package body. In addition, when a flexible synthetic resin-based conductive adhesive is used, the elasticity of the flexible synthetic resin-based conductive adhesive causes thermal expansion between the package body and the piezoelectric element fixed inside the package body. Since it is possible to absorb the difference, it is possible to reliably avoid the occurrence of cracks in the portion of the conductive adhesive against a heat load such as soldering to a printed circuit board, etc. By It is possible to reliably reduce the stress.

[0007]

Therefore, according to the present invention, it is possible to improve the durability against a heat load and prevent the deterioration of the performance against a heat load.

[0008]

Embodiments of the present invention will now be described with reference to the drawings in the case where the embodiment is applied to a package type piezoelectric oscillator having two capacitors of the package type piezoelectric oscillator. FIG.
6 shows a "package type piezoelectric oscillator with a capacitor function" according to the first embodiment.

In the figure, reference numeral 11 indicates a rectangular chip type package body made of an insulating material such as a heat resistant synthetic resin such as epoxy resin, and the upper surface of the package body 11 has a groove type recess. 12 is recessed,
Element electrode films 14 and 15 are formed on the inner surfaces of the left and right ends of the groove-shaped recess 12. In addition, the package body 11 includes three connection terminal electrode films 17, 1
8 and 19 are formed, and these three connecting terminal electrode films 1 are formed.
The connection terminal electrode films 17 and 18 at both ends of the reference numerals 7, 18 and 19 include the lower surface terminal electrode films 17a and 18a formed on the lower surface of the package body 11, the side surface terminal electrode film 17b formed on the side surface of the package body 11, 18b,
Upper surface terminal electrode films 17c and 18c formed on the upper surface of the package body 11 and the groove-shaped recess 12 of the package body 11
Is formed by inner surface terminal electrode films 17d and 18d formed so as to be continuous with the both element electrode films 14 and 15 on the inner wall surface, and the central connection terminal electrode film 19 is the lower surface of the package body 11. The lower surface terminal electrode film 19a formed on the upper surface, the side surface electrode film 19b formed on the side surface of the package body 11, and the upper surface terminal electrode film 19c formed on the upper surface of the package body 11.

Reference numeral 13 denotes a piezoelectric element. The piezoelectric element 13 is a rod-shaped ceramic piece 13a and a lower surface side electrode film formed on the lower surface of the ceramic piece 13a so as to extend from one end to the other end. 13b and an upper surface side electrode film 13c formed on the upper surface of the ceramic piece 13a so as to extend from the other end toward one end. The piezoelectric element 13 is formed in the groove-shaped recess 12 of the package body 11. Is inserted into the lower electrode film 13b.
Is fixed to the one element electrode film 14 in the groove-shaped recess 12 by a conductive adhesive 20, and the other end of the upper surface side electrode film 13c is formed in the groove-shaped recess 12. Similarly, it is fixed to the other element electrode film 15 with a conductive adhesive 21.

Reference numeral 16 denotes a cover plate made of a dielectric material such as barium titanate-based ceramic. The lower surface of the cover plate 16 is a three-dimensional structure for providing the cover body 16 with two capacitor functions. Book capacitor electrode film, that is, capacitor first electrode film 16a, capacitor second electrode film 1
6b and a capacitor third electrode film 16c are formed.

The lid plate 16 is placed on the upper surface of the package body 11 so as to close the groove-shaped recess 12 in the package body 11, and then fixed with an appropriate adhesive 22. At this time, each of the capacitor first electrode film 16a, the capacitor second electrode film 16b, and the capacitor third electrode film 16c on the lower surface of the lid body 16 is formed on the upper surface of the package body 11. The electrode films 17c, 18c and 19c are brought into contact with each other to be electrically conducted.

Then, the piezoelectric element 13 is connected to both element electrode films 14 in the groove-shaped recess 12 of the package body 11,
When the conductive adhesives 20 and 21 are fixed to the resin 15, as the conductive adhesives 20 and 21, for example, a thermoplastic synthetic resin-based conductive adhesive such as an acrylic resin is used. Alternatively, for example, a flexible synthetic resin-based conductive adhesive such as silicone resin is used.

As described above, when a thermoplastic synthetic resin-based conductive adhesive such as acrylic resin is used as the conductive adhesives 20 and 21, the thermoplastic synthetic resin-based conductive adhesive is , When softened by heat,
The difference in thermal expansion between the package body 11 and the piezoelectric element 13 fixed inside the package body 11 can be absorbed. Also,
When a flexible synthetic resin-based conductive adhesive such as a silicone resin is used as the conductive adhesives 20 and 21, the package body 11 is made elastic by the elasticity of the flexible synthetic resin-based conductive adhesive. It is possible to absorb the difference in thermal expansion between the piezoelectric element 13 and the piezoelectric element 13 fixed to the inside.

As a result, both of the conductive adhesives 20, 20 against the heat load such as soldering to the printed circuit board 23, etc.
It is possible to surely avoid the occurrence of cracks at the portion 21 and to reliably reduce stress due to thermal strain generated in the piezoelectric element 13.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a package type piezoelectric oscillator according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5 is a plan view taken along line VV of FIG.

FIG. 6 is an exploded perspective view of a package type piezoelectric oscillator according to an embodiment of the present invention.

[Explanation of symbols]

 11 Package Body 12 Groove-shaped Recess 13 Piezoelectric Element 14, 15 Element Electrode Film 16 Cover Plate 17, 18 Connection Terminal Electrode Film 20, 21 Conductive Adhesive

Claims (2)

[Claims] 1. An element electrode in which a piezoelectric element is formed in a groove-shaped recess formed in the upper surface of an insulating material package and electrodes at both ends of the piezoelectric element are formed on inner bottom surfaces at both ends in the groove-shaped recess. In a package-type piezoelectric oscillator formed by fixing a lid plate to the upper surface of the package while fixing the electrodes so as to be electrically connected to the film, electrodes at both ends of the piezoelectric element are provided at both ends in the groove-shaped recess. A structure of a package type piezoelectric oscillator, characterized in that it is fixed to a device electrode film formed on the inner bottom surface of the device with a thermoplastic synthetic resin-based conductive adhesive. 2. A device in which a piezoelectric element is formed in a groove-shaped recess formed in the upper surface of an insulating material package and electrodes at both ends of the piezoelectric element are formed on inner bottom surfaces at both ends in the groove-shaped recess. In a package type piezoelectric oscillator formed by fixing a lid plate to the upper surface of the package body while being fixed so as to be electrically connected to the electrode film for use, electrodes at both ends of the piezoelectric element are A structure of a package type piezoelectric oscillator characterized in that it is fixed to a device electrode film formed on the inner bottom surface at both ends by a flexible synthetic resin-based conductive adhesive.