JP2004320297A - Piezoelectric vibration device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibration device with more excellent anti-fall-down shock characteristic and higher reliability that can enhance a support strength of a piezoelectric diaphragm. <P>SOLUTION: In the piezoelectric vibration device including a package 1 formed with conductive pads 12, 13, the piezoelectric diaphragm 2 formed with an exciting electrode and leadout electrodes 21, 22, and supported at an end of the piezoelectric diaphragm formed with the leadout electrodes by a conductive resin adhesive member, the leadout electrodes are formed with a conductive region, a non-electrode region, and a recessed part not being a through-hole, and the conductive region, the non-electrode region of the leadout electrodes of the piezoelectric diaphragm and conductive pads of the package are joined with each other by the conductive resin adhesive member while part of the conductive resin adhesive member is intruded to the inside of the recessed part of the piezoelectric diaphragm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a piezoelectric vibrating device using a ceramic package and holding a piezoelectric vibrating plate with a conductive resin adhesive, and more particularly to a structure of a lead electrode of the piezoelectric vibrating plate.
[0002]
[Prior art]
Examples of piezoelectric vibrating devices that require hermetic sealing include quartz oscillators, quartz filters, quartz oscillators, and the like. In each of these cases, a metal thin film electrode is formed on the surface of a quartz vibrating plate (piezoelectric vibrating plate), and hermetically sealed to protect the metal thin film electrode from the outside air. Due to the demand for surface mounting of components, these quartz-applied products are increasingly being housed in a ceramic package in an airtight manner.By selecting an appropriate airtight sealing method, it is possible to ensure good airtightness. it can.
[0003]
For example, as disclosed in Patent Literature 1, the ceramic package as a whole has a rectangular parallelepiped shape in which a storage portion is formed in a central portion, and a conductive pad is formed in a bottom portion in the storage portion. This conductive pad is guided to an external terminal by via or castellation. The quartz vibrating plate has an excitation electrode and a lead-out electrode for connecting the excitation electrode to the outside. The lead-out electrode of the piezoelectric vibrating plate is mounted on the upper surface of the conductive pad of the package, and is electrically connected with a conductive resin adhesive. Mechanically connected. Then, the lid is put on and hermetically sealed.
[0004]
[Patent Document 1]
JP-A-9-199972
[Problems to be solved by the invention]
In recent years, as electronic devices have become smaller and lighter, ultra-small piezoelectric vibrating devices have been required, and the size of piezoelectric vibrating plates housed in packages has also been reduced accordingly. However, when the size of the package is reduced, the holding area is also reduced, so that sufficient bonding strength between the package and the piezoelectric vibration plate cannot be secured, and the impact resistance is significantly reduced. As a conventional method, it is conceivable to increase the application amount of the conductive resin adhesive to improve the bonding strength. However, in a recent miniaturized package, the holding area is small, and there is a danger of a short circuit between terminals (electrodes). There is a problem that the property becomes extremely high.
[0006]
In view of the above, Patent Document 1 mentioned above proposes improving the bonding strength by forming an electrodeless region in a part of the derived electrode. However, when the size of the package is reduced, a region where the conductive resin adhesive is overcoated from the upper portion of the piezoelectric vibration plate cannot be secured, and is held only by the undercoat conductive resin adhesive interposed between the piezoelectric vibration plate and the conductive pad of the package. In such a case, there was a problem that sufficient bonding strength could not be obtained.
[0007]
The present invention has been made in order to solve the above problems, even if the application area of the conductive resin adhesive is limited with the miniaturization of the package, it is possible to improve the holding strength of the piezoelectric diaphragm, It is an object of the present invention to provide a more reliable piezoelectric vibration device having excellent drop impact resistance.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides, as set forth in claim 1, a package in which a conductive pad is formed, and a piezoelectric diaphragm in which an excitation electrode and a lead-out electrode for connecting the excitation electrode to the outside are formed. The piezoelectric vibrating plate is mounted on an upper surface of the conductive pad at an end portion of the piezoelectric vibrating plate on which the lead-out electrode is formed, and is provided by a conductive resin adhesive material interposed between the piezoelectric vibrating plate and the conductive pad. A piezoelectric vibrating device that is held, wherein the lead-out electrode has a conductive region for establishing electrical continuity with the conductive pad, an electrodeless region in which a substrate on a surface of the piezoelectric vibrating plate is exposed, and an inner portion of the piezoelectric vibrating plate. An unpenetrated concave portion exposing the base material is formed, and in a state where a part of the conductive resin adhesive material enters into the concave portion of the piezoelectric vibration plate, the piezoelectric vibration Conduction of lead electrode of plate Range and an electrodeless region, the conductive pads of the package, characterized by comprising bonded to each other.
[0009]
Further, as set forth in claim 2, one or more concave portions are formed in the non-electrode region.
[0010]
Further, as described in claim 3, the concave portion is formed symmetrically on both front and back surfaces of the piezoelectric vibration plate.
[0011]
According to a fourth aspect of the present invention, the piezoelectric vibrating plate is made of a tuning-fork type vibrating piece.
[0012]
【The invention's effect】
According to the present invention, the conductive region and the non-electrode region of the lead-out electrode of the piezoelectric vibrating plate are joined to each other by the conductive resin adhesive, and the conductive pad of the package is connected to each other. At the same time, the interfacial tension (coupling force at the interface) with the conductive bonding material is increased by the base exposed portion of the piezoelectric vibration plate, and the bonding strength is improved. In addition, since a part of the conductive resin adhesive material enters into the concave portion of the piezoelectric diaphragm, an anchor effect is generated, and the mechanical holding strength of the piezoelectric diaphragm is further improved.
[0013]
Therefore, even if the application area of the conductive resin adhesive is limited due to the miniaturization of the package, the holding strength of the piezoelectric vibration plate can be improved, and the more reliable piezoelectric vibration with better drop impact resistance can be obtained. Device can be provided.
[0014]
According to the second aspect, in addition to the above-described effects, by forming the electrodeless region exposing the base material on the plane of the piezoelectric vibrating plate and the concave portion exposing the base material inside the piezoelectric vibrating plate in the same region. A non-electrode region having a higher mechanical bonding strength than the conductive region and a concave portion having the highest mechanical bonding strength are formed in the electrode-less region in a stepwise manner. A synergistic effect is produced by the effect, and the mechanical holding strength of the piezoelectric diaphragm is dramatically improved. In particular, the effect is improved by forming a plurality of recesses in one non-electrode region. In addition, it is possible to easily design and form the conductive region with the lead-out electrode having a limited area, and to secure the conductive region. Therefore, it is possible to suppress the deterioration of the electrical characteristics of the piezoelectric vibration device due to an increase in the contact resistance.
[0015]
According to the third aspect, in addition to the above effects, the concave portions are formed symmetrically on both the front and back surfaces of the piezoelectric vibrating plate. Can be increased.
[0016]
According to the fourth aspect, the present invention can be applied to a piezoelectric vibration device using a tuning-fork type vibrating piece.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment according to the present invention will be described with reference to FIGS. 1 and 2 by taking a surface-mounted crystal oscillator as an example. FIG. 1 is a perspective view showing the present embodiment, and shows a state in which a quartz vibrating plate (piezoelectric vibrating plate) is mounted in a storage section. FIG. 2 is a cross-sectional view along the line AA in a state where the quartz plate of FIG. 1 is mounted. FIG. 3 is a bottom view of the quartz vibrating plate showing the first embodiment. FIG. 4 is a bottom view showing a part of a quartz crystal plate according to a modification of the first embodiment.
[0018]
The surface-mount type crystal unit has a rectangular parallelepiped shape as a whole, a ceramic package 1 having a concave storage portion 1a with an open top, and a crystal vibration plate 2 which is a piezoelectric vibration element stored in the package. Although not shown, it comprises a metal lid joined to the opening of the package.
[0019]
Seen in cross section, the ceramic package 1 is concave and has a bottomed storage section 1a and a bank (side wall) 10 around the storage section. A peripheral metal seal portion 11 is formed on the upper surface of the bank portion 10. The metal seal portion 11 includes a metallized layer made of tungsten or the like, and a metal film layer formed on the metallized layer. The metal film layer includes, for example, a nickel plating layer in contact with the metallization layer, and an extremely thin gold plating layer formed on the nickel plating layer.
[0020]
The bottom of the storage section 1a has steps 1b and 1c, and conductive pads 12 and 13 are formed on the upper surface of the step. The conductive pad has a structure in which a metallized layer using a ceramic lamination technique is plated with nickel or the like, and is led to an external terminal by a via or castellation (not shown).
[0021]
The quartz vibrating plate 2 housed in the ceramic package 1 has a tuning fork shape, and has an excitation electrode (not shown) formed on a leg and an electrode 21 derived from each excitation electrode formed on one end of a base. , 22 are formed. In these electrodes, for example, a gold electrode is formed on a chromium base electrode. The lead-out electrodes 21 and 22 include conductive regions 211 and 221 on which electrodes are formed, and a plurality of electrode-free regions 212 and 222 in which the base material of the surface of the rectangular quartz crystal plate is exposed. Further, a plurality of non-penetrated pinholes (recesses) 213 and 223 exposing the substrate inside the quartz vibrating plate are formed in the electrodeless region. These are formed symmetrically on the front and back surfaces of the quartz diaphragm.
[0022]
Regarding the formation of the pinhole, the number of pinholes is reduced toward the vibrating nodes (near the legs) of the tuning-fork type quartz vibrating plate (in FIG. (3 places in the center, 3 places in the center, and 3 places near both ends in the short side direction), so that the adverse effect of vibration leakage from the quartz plate to the ceramic package is reduced, and the configuration further contributes to the improvement of electrical characteristics. ing.
[0023]
As a method of forming the pinholes, for example, the operation of forming the pinholes 213 and 223 is performed at the same time as forming the tuning-fork-shaped outer shape of the quartz plate by etching or the like. In other words, when a metal pattern of a tuning fork type is formed on a quartz vibrating plate, a metal resist is not provided at a position where the pinhole is to be formed. At the same time, a pinhole is formed in the region of the lead-out electrode of the quartz plate. Regarding this pinhole etching process, by appropriately setting the area of the region where the metal resist is not applied (for example, φ30 as the diameter of the pinhole), a crystal plane appears on the etched surface when the etching proceeds to some extent. Since an etching stop effect (for example, a pinhole depth of, for example, 120 μm and a pinhole depth of, for example, 40 μm) can be used, the etching does not proceed even if the substrate is continuously immersed in a crystal etching solution. Since the pinhole can be formed without depending on the etching time for forming the outer shape of the tuning fork, manufacturing can be simplified.
[0024]
Thereafter, all the metal resist for forming the outer shape of the tuning fork is removed, electrodes are formed on the entire surface of the quartz plate on which the outer shape of the tuning fork and the pinhole are formed, and the resist is formed into a predetermined shape. By providing and performing metal etching, an excitation electrode and a lead-out electrode (a conductive region and a non-electrode region) can be formed.
[0025]
At this time, in the first embodiment of the present invention, a pinhole that exposes the substrate inside the piezoelectric diaphragm is formed near the center of the electrodeless region that exposes the plane substrate of the piezoelectric diaphragm. The electrode film (conductive region) is not in contact with the opening end of the pinhole, and there is no problem such as peeling of the electrode near the opening end of the pinhole during metal etching.
[0026]
As shown in FIG. 2, the lead-out electrodes 21 and 22 of the quartz vibrating plate formed as described above have a part of the conductive resin adhesive D inside the pinholes 213 and 223 (only 223 is shown in FIG. 2). When the conductive resin adhesive D is applied, the conductive regions 211 and 221 (only 221 is shown in FIG. 2) of the lead electrodes of the piezoelectric vibrating plate and the non-electrode regions 212 and 222 (only 222 is shown in FIG. 2). ), The conductive pads 12 and 13 of the package (only 13 is shown in FIG. 2) are joined to each other. Thus, the quartz vibrating plate is more firmly held on one side only by the undercoat conductive resin adhesive interposed between the quartz vibrating plate and the conductive pad of the package.
[0027]
As the conductive resin adhesive, for example, a silicon-based or urethane-based adhesive is used, and the material of the lead-out electrode affects interfacial tension (coupling force at the interface). When a gold electrode is used on the uppermost surface as in the present invention, the interfacial tension with these conductive resin adhesives (coupling force at the interface) decreases, and the holding strength of the quartz diaphragm decreases. The adoption of this configuration has dramatically improved the crystal diaphragm.
[0028]
Although not shown, the metal lid (not shown) is mounted on the metal seal portion 11, and in this state, the metal lid and the metal seal portion are melted by beam welding or seam welding and hermetically sealed.
[0029]
In the lead-out electrode of the first embodiment, a plurality of non-electrode regions where the substrate on the surface of the quartz crystal plate having a rectangular shape is exposed are exposed inside the plurality of electrode-free regions. Although an unpenetrated pinhole is formed, a pinhole shown in FIG. 4 may be used. That is, in FIGS. 4A and 4B, one pinhole is formed inside one non-electrode region so as to correspond thereto. 4C to 4G, the conductive region and the non-electrode region are formed in parallel, and the non-electrode region is formed so as to correspond to the pinhole. FIGS. 4H and 4I show that an electrodeless region is formed on the outer periphery of the conduction region, and a pinhole is formed corresponding to the electrodeless region. Then, these configurations may be appropriately combined and formed.
[0030]
Next, a second embodiment of the present invention will be described with reference to FIG. 5, taking a surface-mount type crystal unit as an example. FIG. 5 is a bottom view of the crystal diaphragm according to the second embodiment. Since the basic configuration is the same as that of the above embodiment, the same components will be described using the same reference numerals, and a description thereof will be partially omitted.
[0031]
The present embodiment is different from the first embodiment in that the non-electrode region and the pinhole formation position in the lead-out electrode are different. That is, the lead-out electrodes 23 and 24 are composed of conductive regions 231 and 241 in which electrodes are formed, and electrode-free regions 232 and 242 in which the base material of the surface of the quartz crystal plate having a rectangular shape is exposed. Further, a plurality of non-penetrating pinholes 233 and 243 exposing a base inside the quartz vibrating plate are formed at positions surrounding the electrodeless region. These are formed symmetrically on the front and back surfaces of the quartz diaphragm. The present invention is not limited to the above-described second embodiment, and electrodeless regions may be formed at positions surrounding the pinholes, or these conductive regions, electrodeless regions, and pinholes may be alternately arranged.
[0032]
Next, a third embodiment of the present invention will be described with reference to FIGS. 6 and 7, taking a surface-mount type crystal unit as an example. FIG. 6 is a bottom view of the quartz vibrating plate showing the third embodiment, and FIG. 7 is a cross-sectional view taken along line BB of FIG. Since the basic configuration is the same as that of the above embodiment, the same components are denoted by the same reference numerals, and the description thereof is partially omitted.
[0033]
In the present embodiment, the shape of the quartz vibrating plate is different from that of the first embodiment. That is, the quartz vibrating plate 3 has a tuning fork shape, and has wide portions 31 and 32 and cutout portions 33 and 34 at its base, and grooves 41 and 42 at the front and back main surfaces of each leg. I have. The provision of these configurations has the following advantages. By forming the wide portions 31 and 32 at the base of the tuning fork, the area of the lead-out electrodes 23 and 24 can be further increased, and the package can be more firmly held. In addition, by forming the cutouts 33 and 34 at the boundary between the tuning fork base and the tuning fork leg, it is possible to reduce the adverse effect of vibration leakage to the package of the crystal vibrating plate firmly held by the wide portion. Further, by forming the grooves 41 and 42 on the front and back main surfaces of each leg of the tuning fork, the CI value characteristics are improved, and a crystal resonator having more excellent electric characteristics can be provided. Each of these components (the wide portion, the notch portion, and the groove) may be formed independently according to the desired characteristics of the crystal unit.
[0034]
In the above-described first to third embodiments, as the concave portion of the lead-out electrode, an unpenetrated pinhole in which the mechanical strength of the quartz vibrating plate is unlikely to decrease with downsizing is taken as an example. Can achieve the same effect. In the case of a large quartz plate, a through hole, a notch or the like can be employed. In the above description, a tuning-fork type quartz vibrator has been exemplified as an example of the piezoelectric vibrating device. Further, for example, in the above-described embodiment, an IC constituting an oscillation circuit may be attached to the lower space of the quartz-crystal vibrating plate, necessary wiring may be performed, and a quartz oscillator may be constituted. It can be applied to other piezoelectric vibration devices such as filters. Further, the present invention is not limited to the ceramic package having a concave shape, and may be applied to a configuration in which a plate-shaped package is provided with an inverted concave lid.
[Brief description of the drawings]
FIG. 1 is a perspective view according to a first embodiment.
FIG. 2 is a cross-sectional view taken along line AA in a state where the quartz plate of FIG. 1 is mounted.
FIG. 3 is a bottom view of the quartz vibrating plate according to the first embodiment.
FIG. 4 is a bottom view showing a part of the quartz vibrating plate showing a modification of the first embodiment.
FIG. 5 is a bottom view of a quartz vibrating plate according to a second embodiment.
FIG. 6 is a bottom view of a quartz vibrating plate according to a third embodiment.
FIG. 7 is a sectional view taken along the line BB of FIG. 6;
[Explanation of symbols]
1 Ceramic package 2, 3 Quartz diaphragm (piezoelectric diaphragm)
12, 13 conductive pads 21, 22, 23, 24 lead-out electrodes

Claims (4)

A package in which a conductive pad is formed, and a piezoelectric diaphragm in which an excitation electrode and a lead-out electrode for connecting the excitation electrode to the outside are formed, and at an end portion of the piezoelectric diaphragm in which the lead-out electrode is formed, A piezoelectric vibration device, wherein the piezoelectric vibration plate is mounted on the upper surface of the conductive pad, and is held by a conductive resin adhesive interposed between the piezoelectric vibration plate and the conductive pad,
The lead-out electrode has a conductive region for obtaining conduction with the conductive pad, an electrodeless region in which the substrate on the surface of the piezoelectric diaphragm is exposed, and a non-penetrating recess that exposes the substrate in the piezoelectric diaphragm. Is formed,
In a state where a part of the conductive resin adhesive material enters into the concave portion of the piezoelectric vibration plate, the conductive resin adhesive material allows the conductive region and the non-electrode region of the lead-out electrode of the piezoelectric vibration plate and the conductive region of the package. A piezoelectric vibration device characterized in that pads are joined to each other. 2. The piezoelectric vibration device according to claim 1, wherein one or a plurality of recesses are formed in the electrodeless region. The piezoelectric vibration device according to claim 1, wherein the recess is formed symmetrically on both front and back surfaces of the piezoelectric vibration plate. The piezoelectric vibrating device according to claim 1, wherein the piezoelectric vibrating plate is formed of a tuning-fork type vibrating piece.

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