JPH11214947A - Package structure for piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a piezoelectric device thin and to improve shock resistance by improving a supporting structure of a piezoelectric vibrator in a ceramic package in a piezoelectric device, which supports a piezoelectric vibrator such as a quartz oscillator inside a package in cantilever and seals it airtightly. SOLUTION: In this piezoelectric device 2, which supports a piezoelectric vibrator 24 on a pad 32 in a recessed part of a package via conductive adhesives 23 in cantilever and seals the recessed part airtightly with a cover 26, an inner bottom plane 21a of the recessed part of the package is an inclination plane, one end part of the vibrator 24 is supported on the pad that is provided on a lower side of the plane 21a via the adhesives 23 in cantilever and also, the other end of the vibrator 24 is arranged, facing an upper side of the plane 21a with a microscopic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a piezoelectric device having a structure in which a piezoelectric vibrator such as a quartz vibrator is supported in a cantilever state in a package and hermetically sealed. More specifically, the present invention relates to a piezoelectric vibrator in a ceramic package. The present invention relates to a package structure of a piezoelectric device in which the thickness of a piezoelectric device is reduced by improving a supporting structure of a child.

[0002]

2. Description of the Related Art Piezoelectric devices having a structure in which a piezoelectric vibrator such as a crystal vibrator is hermetically sealed in a package are used as a reference frequency generating source in electronic devices such as various communication devices and OA devices. As electronic devices become smaller and thinner, piezoelectric devices are also required to be smaller and thinner. FIG. 4 is a longitudinal sectional view showing an example of a package structure of a conventional piezoelectric device using a crystal unit. This piezoelectric device is composed of two steps 2 and 3 opposed to each other on the inner bottom surface of the recess of the ceramic package 1. A quartz oscillator 5 is supported in a cantilever state on the upper surface of one of the steps 2 via a conductive adhesive 4, and the opening of the recess (upper frame upper surface 1 a) is hermetically sealed with a metal lid 6. It has a configuration as described below. The crystal resonator 5 has a configuration in which excitation electrodes and leads led out from the respective excitation electrodes to the edges of the plate are formed on both front and back surfaces of the crystal blank. And conductors 10, 1 with respect to output electrodes 7, 8
1, connected via a pad 12. The upper surfaces of the two steps 2 and 3 are formed horizontally, similarly to the package inner bottom surface 1b, and the heights and areas of the upper surfaces of the steps 2 and 3 are set to be equal. Thus, the crystal oscillator 5 can be cantilevered on any of the steps 2 and 3 without directionality when the crystal oscillator 5 is mounted. The other end of the quartz oscillator 5 opposite to the one end supported by the conductive adhesive 4 is supported by being floated a predetermined distance from the upper surface of the other step 3. The other step 3 is opposed to the other end of the crystal unit 5 in a non-contact state because the step 3 is deformed when an external impact is applied such as when a device including a piezoelectric device is dropped. This is because the other end of the crystal unit comes into contact with the upper surface of the step 3 so as to exhibit a function as a so-called pillow member for absorbing a shock and avoiding breakage.

[0003]

However, the above-mentioned conventional package of the crystal resonator has the following disadvantages.
First, when the thickness of the ceramic package is reduced due to the demand for smaller and thinner components mounted on the printed circuit board,
The inner bottom surface 1b of the ceramic package is a quartz oscillator 5
Must not be in contact with the central part of the package, and it is necessary to provide two steps including the step 3 serving as a pillow member. Therefore, the inside of the package has a total of three steps, which hinders the reduction in thickness. ing. The height of the steps 2 and 3 needs to be set to the same level in order not to give directionality when mounting the crystal unit 5 inside the package. The gap between the other end of the package and the upper surface of the step 3 serving as a pillow member becomes excessively large, which is a factor that hinders the reduction in thickness of the package. That is,
As a result of cantilevering one end of the crystal unit 5 on the step 2 via the conductive adhesive 4, only the thickness of the conductive adhesive 4 located between the lower surface of one end of the crystal unit 5 and the upper surface of the step 2 is obtained. In addition, there is a problem that a gap between the other end of the crystal unit and the upper surface of the step 3 becomes large. However, in view of the effect of absorbing and relaxing the impact, it is preferable that the gap is as small as possible, and there is a limit in reducing the gap in the above-described conventional crystal oscillator supporting structure. The problem to be solved by the present invention is to provide a piezoelectric device having a structure in which a piezoelectric vibrator such as a crystal vibrator is supported in a cantilever state inside a package and hermetically sealed, and a supporting structure of the piezoelectric vibrator in a ceramic package is provided. By making improvements, thinning of piezoelectric devices,
And to improve the impact resistance.

[0004]

According to a first aspect of the present invention, a piezoelectric vibrator is supported in a cantilever manner on a pad in a recess of a package via a conductive adhesive. In a piezoelectric device having a structure in which the recess is hermetically sealed with a lid, an inner bottom surface of the recess of the package is formed as an inclined surface, and a piezoelectric vibration is applied to a pad provided on a downside of the inner bottom surface via a conductive adhesive. One end of the piezoelectric element is supported in a cantilever state, and the other end of the piezoelectric vibrator is opposed to a rising side of an inner bottom surface with a small gap therebetween. The invention according to claim 2 is characterized in that the inner bottom surface of the recess of the package is a quadratic curved inclined surface.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view showing a package structure of a piezoelectric device according to an embodiment of the present invention. This piezoelectric device 20 includes a ceramic package 21 having a recess 22 on the upper surface and an inner bottom surface 21a of the ceramic package 21. A quartz vibrator (piezoelectric vibrator) 24 whose one end is supported in a cantilever state via a conductive adhesive 23 at a position close to one end, and fixed on the outer frame upper surface 21a of the package 21 via a seam ring 25 or the like. The recess 22
And a metal lid 26 for hermetically sealing the device. Crystal oscillator 24
Has a configuration in which excitation electrodes on both the front and back surfaces of a strip-shaped quartz crystal plate and leads led out from each excitation electrode to the edge of the plate are formed by vapor deposition or the like, and each lead is provided on the outer bottom surface of the package Conductor 3 for input and output electrodes 27, 28
0, 31 and pad 32 are connected. A characteristic configuration of this embodiment is that a package inner bottom surface 21a is inclined upward from one end edge on the left side in the drawing to the other end edge on the right side in the drawing, and a pad provided at a downward position of the inclined inner bottom surface 21a. 32, one end of the quartz oscillator 24 is fixed in a cantilever state via a conductive adhesive 23, and the other end of the quartz oscillator 24 is fixed to a predetermined position on the upside of the inclined inner bottom surface 21a by a predetermined minute distance. They are arranged facing each other with a gap therebetween. In the ceramic package 21 having the above configuration, the other end side of the crystal unit not held by the conductive adhesive 23 has a small gap between itself and the bottom surface of the package. The function of absorbing a shock is exhibited, and an increase in the package height caused by protruding a special pillow member can be avoided. In other words, it is possible to achieve a three-stage structure in a package for providing a pillow member like the above-described conventional package and a height reduction accompanying the two-stage structure without incurring an increase in height.
Note that the inner bottom surface of the package of the above embodiment is an inclined surface extending linearly, but this is an example, and for example, the inner bottom surface is curved and inclined in a quadratic curve as shown in FIG. Is also good. Note that the piezoelectric vibrator used in the present invention is not limited to a quartz vibrator, and various piezoelectric materials can be used.

FIGS. 3 (a) and 3 (b) are simplified diagrams for explaining the above-mentioned conventional method for manufacturing a ceramic package and the method for manufacturing a ceramic package of the present embodiment.
The conventional ceramic package 1 shown in FIG. 3A is manufactured by stacking, for example, three ceramic sheets 40a, 40b, and 40c and then hardening them.
Among them, the center ceramic sheet 40b forms steps 2 and 3. In such a conventional ceramic package, since three ceramic sheets are required, the process is complicated and the cost is increased. In contrast,
The ceramic package 20 of the present invention shown in FIG.
Since the two ceramic sheets 41a and 41b are laminated, the configuration is simple and the manufacturing cost is easy. Note that any of the above ceramic packages is actually manufactured by a batch process using a large-area sheet base material. The material of the package of the present invention is not limited to ceramic.

[0007]

As described above, the present invention relates to a piezoelectric device having a structure in which a piezoelectric vibrator such as a crystal vibrator is supported in a cantilever state in a package and hermetically sealed. By improving the support structure, the thickness of the piezoelectric device can be reduced and the impact resistance can be improved. Specifically, by making the bottom surface in the recess of the package an inclined surface, it is possible to achieve a reduction in the thickness of the package without providing a special step that may increase the height of the package. In addition, by not providing a step, the number of stacked ceramic packages can be reduced, the process can be simplified, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a package structure of a piezoelectric device according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a package structure of a piezoelectric device according to another embodiment of the present invention.

FIGS. 3 (a) and 3 (b) are diagrams showing a conventional method of manufacturing a ceramic package and a method of manufacturing a ceramic package of the present embodiment, respectively.

FIG. 4 is a diagram showing a conventional package structure.

[Explanation of symbols]

20 piezoelectric device, 21 ceramic package, 2
2 recess, 23 conductive adhesive, 24 quartz oscillator (piezoelectric oscillator), 25 seam ring, etc., 26 metal cover, 2
7, 28 electrodes, 30, 31 conductors, 32 pads.

Claims (2)

[Claims] 1. A piezoelectric device having a structure in which a piezoelectric vibrator is supported in a cantilevered state on a pad in a recess of a package via a conductive adhesive in a cantilever manner, and the recess is hermetically sealed with a lid. The inner bottom surface of the concave portion is an inclined surface, and one end of the piezoelectric vibrator is supported in a cantilever state via a conductive adhesive on a pad provided on the downside of the inner bottom surface, and the piezoelectric vibrator A package structure for a piezoelectric device, wherein the other end is opposed to an upside of an inner bottom surface with a small gap therebetween. 2. The package structure for a piezoelectric device according to claim 1, wherein the inner bottom surface of the recess of the package is a quadratic curved inclined surface.