JP2004357131A - Piezoelectric vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of a conventional piezoelectric vibrator using a plurality of bumps to support a piezoelectric diaphragm subjected to beveling processing, wherein support of the piezoelectric diaphragm is unstable because of a difference in bonding strength caused by variation in the kinetic energy applied to each bump at bonding. <P>SOLUTION: In the piezoelectric vibrator, the piezoelectric diaphragm on a principal face of piezoelectric raw plate of which exciting electrodes, lead electrodes extended from the exciting electrodes, and connection electrodes taking the continuity to a package are formed, is contained in the package in the inside of which electrode pads are formed; and the bumps are used for taking continuity between the connection electrodes and the electrode pads and for taking supporting attitude of the piezoelectric diaphragm. The piezoelectric vibrator is characterized in that the electrode pads are formed by stacking metallic layers in multi-stages corresponding to a thickness change in the principal face of the piezoelectric diaphragm in order to form the bumps to have the same size and the same shape. <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 having a piezoelectric vibrating plate in which electrodes are formed on a beveled piezoelectric element plate.
[0002]
2. Description of the Related Art A piezoelectric vibrating plate used for a piezoelectric vibrator, which is one of electronic components, has a structure in which an excitation electrode for exciting the piezoelectric plate and an external terminal are connected to the front and back main surfaces of the piezoelectric plate. And a lead-out electrode for electrically connecting the excitation electrode and the external connection terminal. With the downsizing of the piezoelectric vibrator, a small strip shape has become the mainstream as a raw plate shape. However, as the size of the piezoelectric element plate is reduced, the crystal impedance (hereinafter referred to as CI) is increased, which has an adverse effect on the excitation starting characteristics of the piezoelectric vibration plate.
[0003]
In order to lower this CI value, in the state of the piezoelectric element, a process of making the contour portion of the piezoelectric element thinner than the central portion of the piezoelectric element (beveling process) is performed to force propagation of the excitation to the contour portion. Attenuation has been done. The main surface of the quartz plate constituting the quartz vibrating plate has an edge on each side compared to the substantially flat portion formed at the center of the piezoelectric plate, onto which the inner surface shape of the processing vessel used for beveling is transferred. The shape is gradually reduced toward the shape (beveling shape).
[0004]
FIG. 5 discloses a conventional piezoelectric vibrator in which a beveled piezoelectric vibrating plate is mounted. First, on the front and back main surfaces of the piezoelectric element plate 52 processed into the beveling shape, opposing excitation electrodes 53, and extraction electrodes 54 extending from the excitation electrode 53 to one short side of the piezoelectric element plate 52 are provided. A connection electrode 55 that is electrically connected to the extraction electrode 54 and establishes electrical continuity with the electrode pad 57 on the container 56 side is formed to constitute the piezoelectric vibration plate 51.
[0005]
The piezoelectric vibration plate 51 thus configured is arranged in the space of the container 56 so as to be substantially parallel to the bottom surface inside the container. At this time, the connection electrode 55 on the piezoelectric vibration plate 51 side and the container 56 The electrode pad 57 on the side is electrically connected with a bump 58 made of a metal material such as gold, and the bump 58 also holds the posture of the piezoelectric vibration plate 51 inside the container 56. After the piezoelectric vibrating plate 51 is mounted in the space inside the container 56, a metal lid (not shown) is placed at the opening of the container 56, and the space inside the container 56 is hermetically sealed, so that the piezoelectric vibrator 50 is mounted. It is formed.
[0006]
Conventionally, in order to maintain the conduction between the connection electrode formed on the beveling-shaped piezoelectric vibration plate and the electrode pad on the container side by a bump, in response to a change in the thickness dimension of the main surface of the piezoelectric vibration plate, As shown in FIG. 6, bumps are further formed on the bumps, and the size of the bumps is changed depending on the positions where the bumps are formed as shown in FIG.
[0007]
The following documents are disclosed for the piezoelectric vibrating plate as described above.
[0008]
[Patent Document 1]
JP-A-8-298423 [Patent Document 2]
JP-A-11-289238
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.
[0010]
However, in the case where the bumps are formed in an overlapping manner as in the above-mentioned conventional example, the number of steps for forming the bumps increases, and a high precision in forming the bumps on the bumps is required. Manufacturing equipment is required. Further, even when the bumps are formed by changing the size, a means for controlling the change in the size of the bumps is separately required, and the cost is increased accordingly.
[0011]
Further, as the size of the piezoelectric vibrator is reduced, the size of the piezoelectric vibrating plate itself mounted inside the piezoelectric vibrator also needs to be reduced, and accordingly, the area where the connection electrodes can be formed on the main surface of the piezoelectric vibrating plate is very narrow. Thus, the shape of the connection electrode is reduced. Therefore, when the size of the bump is changed, the size may be limited.
[0012]
In addition, by forming the bumps on top of each other or by changing the size of each bump, differences in the bonding strength between the connection electrodes and the electrode pads for each bump and the bonding energy applied to the bumps during bump formation are reduced. Will happen. For this reason, when stress is applied from the outside to the piezoelectric vibrator and the piezoelectric vibrating plate mounted inside the piezoelectric vibrator, conduction and attitude holding between the connection electrode and the electrode pad become unstable, resulting in deterioration of characteristics and worst case. In this case, there is a possibility that the piezoelectric vibrating plate may fall off. In such a case, in order to obtain the required bonding strength with all the bumps, a larger force must be applied to the connection surfaces between the connection electrodes and the electrode pads and the bumps. Unnecessary stress is applied to the substrate, which may adversely affect the characteristics.
[0013]
DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a pair of excitation electrodes facing each other on the front and back main surfaces of a beveled piezoelectric element. A lead electrode extending from the excitation electrode to one short side of the piezoelectric element plate and a connection electrode for electrically connecting to the lead electrode and establishing conduction with the container were formed near the short side edge. The piezoelectric vibrating plate is housed in an insulating container having an electrode pad formed therein, and the bump is used in a piezoelectric vibrator using a bump for conducting between the connecting electrode and the electrode pad and supporting the piezoelectric vibrating plate. A piezoelectric vibrator characterized in that, in order to have the same dimensions and the same shape, the electrode pads are formed by laminating metal layers in multiple stages corresponding to the thickness dimension change of the main surface of the piezoelectric diaphragm.
[0014]
Therefore, in the piezoelectric vibrator of the present invention, the beveling-shaped piezoelectric vibrating plate can be maintained conductive with uniform bonding strength by only the single-shaped bump.
[0015]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the piezoelectric vibration plate according to the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing one embodiment of a container used for the piezoelectric vibrator according to the present invention. FIG. 2 is a sectional view taken along line A1-A2 in FIG. FIG. 3 is a plan view showing one embodiment of a piezoelectric vibrating plate in which various electrodes are formed on a piezoelectric plate subjected to beveling. FIG. 4 is a partial cross-sectional view showing, in an enlarged form, a portion corresponding to a dotted circle B in FIG. 2 in a configuration in which the piezoelectric vibrating plate disclosed in FIG. 3 is mounted on the container disclosed in FIGS. It is.
In FIG. 3, in order to more clearly show the form of the main surface of the piezoelectric vibrating plate, a line segment connecting portions of the same thickness on the surface with a line is described. Further, in each of the drawings, a part of the structure is not shown for clarity, and the dimensions are partially exaggerated.
[0016]
That is, in FIG. 1 and FIG. 2, the piezoelectric vibrating plate (not shown in FIG. 1 and FIG. 2) A step 11 is formed to hold and mount one end of the step. On the upper surface of the step portion 11, an electrode pad 13 having a laminated structure of a metal material, which is electrically connected to the external connection electrode 12 formed on the outer bottom surface of the container, is formed.
[0017]
FIG. 3 shows a piezoelectric vibrating plate 30 mounted inside the container shown in FIGS. 1 and 2, and the main surface of a quartz crystal plate 31 constituting the piezoelectric vibrating plate 30 is used for beveling processing. The inner shape of the processed container is transferred, and is processed into a shape (beveling shape) in which the thickness gradually decreases toward each side end as compared with the substantially flat portion formed at the center of the piezoelectric element plate. . On its main surface, an opposing excitation electrode 32, an extraction electrode 33 extending from the excitation electrode 32 to one short side of the piezoelectric element plate 31, A connection electrode 34 for establishing conduction with the electrode pad 13 on the side is formed.
[0018]
In the electrode pad 13 shown in FIGS. 1 and 2, the lowermost first electrode pad layer 14 is formed to have a size equal to or larger than the size of the connection electrode 34 formed on the piezoelectric vibration plate 30 described above. I have. In the second electrode pad layer 15 formed on the first electrode pad layer 14, a corner toward the center of the container 10 is chamfered in an arc-shaped curve toward the center of the electrode pad layer. Is chamfered into a shape similar to a curve corresponding to a line segment shown on the main surface of the piezoelectric vibration plate 30 subjected to the beveling process shown in FIG.
[0019]
The piezoelectric vibration plate 30 configured as described above is arranged in the space of the container 10 in which the above-described electrode pad 13 is formed as shown in FIG. At this time, a gap between the connection electrode 34 on the piezoelectric vibrating plate 30 side and the first and second electrode pad layers 14 and 15 constituting the electrode pad 13 on the container 10 side is made of a single metal material such as gold. Conductive connection is made by a plurality of bumps 16 of one shape. The bumps 16 also hold the posture of the piezoelectric vibration plate 30 inside the container 10. Thereafter, a metal lid (not shown) is disposed at the opening of the container 10 having the piezoelectric vibration plate 31 mounted in the internal space, and the internal space of the container 10 is hermetically sealed to form a piezoelectric vibrator. Is done.
[0020]
As described above, by forming the electrode pads of the piezoelectric vibrator held by the piezoelectric vibrating plate in the above-described shape, it is not necessary to perform any special operation at the time of bump formation as in the related art. In addition, since a single-shaped bump can be formed, conduction of the piezoelectric vibration plate can be maintained with uniform bonding strength. Furthermore, since the laminated structure of the electrode pads corresponds to the change in the thickness of the beveled surface of the piezoelectric vibrating plate, even if the connecting electrodes of the piezoelectric vibrating plate become smaller due to the miniaturization of the piezoelectric vibrator, the size of the bumps will increase It will be possible to respond by reducing the size.
[0021]
In this embodiment, a two-layer structure including the first electrode pad layer and the second electrode pad layer is disclosed as a laminated structure of the electrode pads. However, in order to cope with a change in the thickness of the beveling shape of the piezoelectric diaphragm more finely. Alternatively, an electrode pad having a laminated structure of two or more layers may be used.
[0022]
As described in detail above, compared to the piezoelectric vibrator according to the present invention, no special equipment is required when forming the bumps, the number of steps can be reduced, and the bump bonding strength at the time of holding can be made uniform. Accordingly, an effect of providing a piezoelectric vibrator which is inexpensive and has good characteristics can be provided.
[Brief description of the drawings]
FIG. 1 is a plan view showing one embodiment of a container used for a piezoelectric vibrator according to the present invention.
FIG. 2 is a sectional view of the container when cut along a line A1-A2 shown in FIG.
FIG. 3 is a plan view showing one embodiment of a piezoelectric diaphragm subjected to beveling processing.
FIG. 4 is an enlarged partial cross-sectional view of a portion corresponding to a dotted circle B in FIG. 2 in a piezoelectric vibrator according to the present invention in which a piezoelectric vibrating plate is mounted on a container to form a piezoelectric vibrator. FIG.
FIG. 5 is a sectional view of a conventional piezoelectric vibrator.
FIG. 6 is an enlarged partial cross-sectional view of a portion corresponding to a dotted circle C in FIG. 5, which discloses an embodiment of a bump forming mode in a conventional piezoelectric vibrator.
FIG. 7 is an enlarged partial cross-sectional view showing a portion corresponding to a dotted-line circle C in FIG. 5, which discloses another embodiment of a bump forming mode in a conventional piezoelectric vibrator.
[Explanation of symbols]
10, container 13, electrode pad 14, first electrode pad layer 15, second electrode pad layer 16, bump 30, piezoelectric vibration plate 31, piezoelectric element plate 32, excitation electrode 33, extraction electrode 34, connection electrode

Claims (1)

On the front and back main surfaces of the piezoelectric element subjected to beveling, opposing excitation electrodes, an extraction electrode extending from the excitation electrode to one short side of the piezoelectric element, and electrically connected to the extraction electrode. A piezoelectric vibrating plate in which a connection electrode for connecting and establishing conduction with a container is formed near a short side edge is housed in an insulating container having an electrode pad formed therein, and the connection electrode and the electrode pad are stored. In the piezoelectric vibrator using the bumps for conduction between and maintaining the posture of the piezoelectric vibration plate,
A piezoelectric vibrator characterized in that the electrode pads are formed by laminating metal layers in multiple stages corresponding to the thickness dimension change of the main surface of the piezoelectric vibrating plate so that the bumps have the same dimensions and the same shape. .

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