JP2004304376A - Chip piezoelectric vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that there is the possibility of increasing the danger of airtight leakage by the stress caused by the difference of the coefficient of thermal expansions by heating at the time of sealing and reflowing to a mother substrate, since a chip piezoelectric vibrator in the conventional technology uses a piezoelectric diaphragm as a portion of a member constituting the external shape of a piezoelectric vibrator and hermetic sealing is performed in two places of both surfaces of the piezoelectric diaphragm to increase the man-hours and there are differences in the quality of the materials between the piezoelectric diaphragm and an insulating plate. <P>SOLUTION: In this chip piezoelectric vibrator, a first container in which a recess having a level difference is formed, an external connection electrode is formed on the external surface of both end edge parts in the length direction, and an internal connection pad is electrically connected to the external connection electrode respectively, and constituted of an insulating material, and a second container of the same shape in the configuration and the same material as those of the first container are joined together at the top of recess walls of the first and second containers. The piezoelectric diaphragm is mounted on the space made by the recesses of the first and second container. The space is hermetically sealed to form the chip piezoelectric vibrator. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator, and more particularly to a small chip type piezoelectric vibrator.
[0002]
2. Description of the Related Art In recent years, there has been a strong demand for miniaturization of electronic components such as a piezoelectric vibrator and a piezoelectric oscillator mounted on an electronic device, and an ultra-small chip shape having a length of 2 mm or less has been desired. . Accordingly, piezoelectric vibrators of various shapes have been invented.
[0003]
FIG. 3 is a diagram illustrating an example of a chip-type piezoelectric vibrator disclosed as a conventional technique. That is, the piezoelectric vibrator 30 includes insulating plates 32 and 33 having the same shape as the piezoelectric vibrating plate 31 such that a cavity is formed in an exciting electrode portion on both surfaces of a piezoelectric vibrating plate 31 having excitation electrodes formed on both main surfaces. Are arranged, and each is fixed to the piezoelectric substrate 31 to form the outer shape of the piezoelectric vibrator 30.
[0004]
A lead electrode is formed from the excitation electrode of the piezoelectric vibrating plate 31 to the edge of the piezoelectric vibrating plate, and this lead electrode is electrically connected to external connection electrodes 34 and 35 formed on the outer surface of the piezoelectric vibrator 30. Thus, a chip-type piezoelectric vibrator is formed.
[0005]
In addition, as another type of chip type piezoelectric vibrator, a piezoelectric vibrating plate is mounted in a cylindrical case, external connection terminals are fitted to both ends of the tube, and an electrode formed on the main surface of the piezoelectric vibrating plate is connected to an external device. A chip-type piezoelectric vibrator electrically connected to a connection terminal is also disclosed.
[0006]
The following documents are disclosed for the piezoelectric vibrator as described above.
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 06-140868 [Patent Document 2]
JP-A-06-132768
The applicant has not found any prior art documents related to the present invention other than the prior art documents specified in the above-mentioned prior art document information by the time of filing the present application.
[0009]
As the size of the piezoelectric vibrator has been reduced and the maximum external dimension of the piezoelectric vibrator has been reduced to 2 to 3 mm or less, while maintaining or improving various characteristics and reliability of the piezoelectric vibrator, Further, it is required that the mounting on the motherboard is simple.
[0010]
However, in a piezoelectric vibrator having a structure similar to that of the prior art, since the piezoelectric vibrating plate is used as a part of a member constituting an outer shape of the piezoelectric vibrator, a portion to be hermetically sealed is provided on both sides of the piezoelectric vibrating plate. There will be two places and the man-hour will increase. In addition, since the material is different between the piezoelectric vibrating plate and the insulating plate, the risk of airtight leakage increases due to the stress generated by the difference in the coefficient of thermal expansion due to heating during sealing or reflow to the mother substrate, May cause a decrease in the reliability of the device. Further, since the piezoelectric vibrating plate is exposed on the surface of the component, an impact is easily applied to the piezoelectric vibrating plate directly from the outside, and cracks and the like easily occur in the piezoelectric vibrating plate itself.
[0011]
Furthermore, since the external shape of the cylindrical chip type piezoelectric vibrator is cylindrical, it cannot be easily arranged stably at an arbitrary position on the mother substrate. Further, also in the cylindrical chip type piezoelectric vibrator, a portion for hermetically sealing the inside of the cylinder is provided at two places at both ends of the cylinder, so that the number of steps is increased. In addition, since the material is different between the cylindrical body and the electrode portions at both ends, stress generated around the sealing material due to a difference in coefficient of thermal expansion due to heating at the time of sealing or reflow to the mother substrate causes the sealing material or its surroundings. There is a high risk that cracks will occur in the structure and airtight leakage will occur, leading to a reduction in the reliability of the component. Further, since the number of components constituting the piezoelectric vibrator is large, the production management becomes complicated, and the production cost increases.
[0012]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has a connection pad formed therein as a space for accommodating the piezoelectric vibration plate, the connection pad being fixedly connected to the piezoelectric vibration plate. A concave portion having a stepped portion is formed, and external connection electrodes are formed on outer surfaces of both end portions in the length direction, and the connection pad and the external connection electrode are electrically connected to each other. A first container made of a substance and a second container having the same configuration and the same material as the first container are joined at the top of the concave wall of the first container and the second container. A chip-type piezoelectric vibrator characterized in that a piezoelectric vibrating plate is mounted in a space defined by concave portions of a first container and a second container formed by the above method, and the space is hermetically sealed.
[0013]
Further, in the above-mentioned chip type piezoelectric vibrator, the height dimension of the first container and the second container is の of the width dimension of the piezoelectric vibrator.
[0014]
By using the chip-type piezoelectric vibrator having such a structure, the hermetic sealing can be performed at one location, and the opposing structures at the one sealing location have the same shape and configuration. It is possible to minimize the stress applied to the sealing portion due to the difference in coefficient of thermal expansion. Further, by making the outer shape of the piezoelectric vibrator into a cubic shape and making the height dimension and the width dimension substantially the same, there is an effect that the piezoelectric vibrator can be mounted on the motherboard using all the side surfaces in the length direction.
[0015]
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially exploded configuration diagram of a chip type piezoelectric vibrator according to the present invention. FIG. 2 is a sectional view of the disassembled part of FIG. 1 cut along an assembly line A1-A2. In FIGS. 1 and 2, a part of the structure is not shown for clarity, and the dimensions are partially exaggerated.
[0016]
That is, the outer shape of the chip-type piezoelectric vibrator 10 illustrated in FIGS. 1 and 2 is configured by the first container 11 and the second container 12. First, the first container 11 is formed of ceramics, and serves as a space for accommodating the piezoelectric vibration plate 13 having excitation electrodes formed on the front and back main surfaces therein, and a connection pad (not shown) which is fixedly connected to the piezoelectric vibration plate 13. A recess 15 having a step portion 14 formed with () is formed. External connection electrodes 16 and 17 are formed on the outer surfaces of both ends in the longitudinal direction of the first container 11, and the connection pads and the external connection electrodes 16 and 17 are respectively disposed between adjacent pads and electrodes. Electrically connected.
[0017]
The second container 12 has the same configuration and the same material as the first container 11. That is, as a space for accommodating the piezoelectric vibrating plate 13 formed of ceramics and having excitation electrodes formed on the front and back main surfaces therein, a stepped portion in which connection pads (not shown) which are fixedly connected to the piezoelectric vibrating plate 13 are formed. A recess 19 having 18 is formed. External connection electrodes 20 and 21 are formed on the outer surfaces of both ends in the longitudinal direction of the second container 12, and the connection pads and the external connection electrodes 20 and 21 are respectively disposed between adjacent pads and electrodes. Electrically connected.
[0018]
The first container 11 and the second container 12 described above are joined together in a state in which the piezoelectric vibrating plate 13 is mounted on the space 22 formed by the concave portions 15 and 19 with the wall tops of the concave portions 15 and 19 respectively. The inside of 22 is hermetically sealed. In the present embodiment, a low-melting glass 23, which is one of the sealing materials, is applied to the entire top of the wall of the first container 11 and then the second container 12 is mounted with a piezoelectric vibration plate mounted inside. And the whole is heated to melt the low-melting glass, and the first container 11 and the second container 12 are joined to hermetically seal the piezoelectric vibration plate 13 and the space 22.
[0019]
As described above, since the first container 11 and the second container 12 are simply joined together, the number of sealing locations where air leakage is most likely to occur can be reduced to a minimum of one. The probability of the occurrence of is reduced. In addition, the first container 11 and the second container 12 facing each other at the sealing location are made of the same shape and the same ceramic, so that the piezoelectric vibrator 10 is reflowed at the time of hermetic sealing and on a mother substrate. It is possible to minimize the stress applied to the sealing portion due to the difference in the coefficient of thermal expansion, which occurs during the heating or heat radiation when mounting due to the difference between the low melting point glass 23 and the first Airtight leakage due to cracks generated near the top of the wall of the container or the second container can be prevented.
[0020]
In the present embodiment, the height H1 of the first container 11 is set to １ ／ of the width W1 of the first container, and the height H2 of the second container 12 is set to the width W2 of the second container. The height H and the width W (same dimensions as W1 and W2) of the assembled piezoelectric vibrator 10 are made substantially equal to each other. With the piezoelectric vibrator 10 having such external dimensions, when the piezoelectric vibrator 10 is mounted on the motherboard, the piezoelectric vibrator 10 can be mounted even if any side in the length direction of the piezoelectric vibrator 10 faces the motherboard. Therefore, it is not necessary to consider the front and back of the piezoelectric vibrator when mounting the piezoelectric vibrator on the motherboard, and the mounting work can be performed very easily.
[0021]
Further, since the first container 11 and the second container 12 have the same shape and configuration and the same material, the number of parts can be regarded as one, and a package including a cylindrical chip type piezoelectric vibrator or a lid and a container is provided. As compared with a chip-type piezoelectric vibrator utilizing the method, the production management becomes easier and the production cost can be reduced.
[0022]
According to the piezoelectric vibrator of the present invention, the hermetic sealing can be performed at one location, and the opposing structures at the one sealing location have the same shape, structure and material. To minimize the stress applied to the sealing part due to the difference in the coefficient of thermal expansion, thereby preventing the occurrence of airtight leakage and providing a highly reliable chip-type piezoelectric vibrator. The effect that can be achieved. Also, by making the external shape of the piezoelectric vibrator into a cube and making the height and width dimensions almost the same, mounting on the motherboard can be performed using all side surfaces in the length direction, making mounting work easier. This provides an effect that a simple piezoelectric vibrator can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a chip-type piezoelectric vibrator according to the present invention.
FIG. 2 is a sectional view taken along line A1-A2 shown in FIG.
FIG. 3 is a perspective view of a conventional chip-type piezoelectric vibrator.
[Explanation of symbols]
10, piezoelectric vibrator 11, first container 12, second container 13, piezoelectric vibrators 14, 18, step portions 15, 19, concave portions 16, 17, 20, 21, external connection terminal 22, space

Claims (2)

As a space for accommodating the piezoelectric vibrating plate therein, a concave portion having a stepped portion formed with a connection pad which is fixedly connected to the piezoelectric vibrating plate is formed, and external connection electrodes are provided on outer surfaces of both longitudinal end portions. The connection pad and the external connection electrode are electrically connected to each other, and a first container made of an insulating material, and a second container having the same shape and the same material as the first container. And the first container and the second container are joined at the tops of the recessed walls of the first container and the second container, and the piezoelectric vibrating plate is mounted in a space formed by joining the first container and the second container. A chip-type piezoelectric vibrator characterized in that the space is hermetically sealed. 2. The chip-type piezoelectric vibrator according to claim 1, wherein a height of the first container and a height of the second container are の of a width of the piezoelectric vibrator.

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