JP2002158558A - Package for piezoelectric vibrating device and piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a package for piezoelectric vibrating device and a piezoelectric oscillator, which can be miniaturized and shortened, and can package piezoelectric diaphragms of different external sizes. SOLUTION: A crystal oscillator is composed of a ceramic package 1, and an IC 33 and a crystal diaphragm 3 stored inside the relevant package and a metal lid 2 for air-tightly sealing the package. Packaging parts 14 and 15, composed of metal films for supporting the crystal diaphragm, have low height packaging parts 141 and 151 on the center side of the package, have high packaging parts 142 and 152 on the terminal side of the package and have auxiliary packaging parts 13. Using these packaging parts, the crystal diaphragms of the different external sizes can be packaged selectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrating device such as a piezoelectric oscillator or a piezoelectric vibrator used for a communication device such as a cellular phone or an electronic device, and more particularly to a support structure for a piezoelectric vibrating plate. .

[0002]

2. Description of the Related Art Piezoelectric vibrators and piezoelectric oscillators are used in various fields as a reference frequency source for electronic equipment and the like in recent years because a stable and highly accurate oscillation frequency can be obtained. The used surface mount type is the mainstream. As a conventional example, see Japanese Patent Application Laid-Open No. 3-8837.
A description will be given taking No. 3 as an example. JP-A-3-88373 discloses that
This is a configuration in which a ceramic package is used, holding electrodes are formed inside the package, and a piezoelectric piece (piezoelectric vibration plate) is cantilevered.

The natural frequency of a piezoelectric vibrating plate used here, for example, an AT-cut quartz vibrating plate, is inversely proportional to its thickness. Therefore, in the low frequency band, the larger outer size is more advantageous in terms of electrical characteristics, but in the higher frequency band using the fundamental wave, the quartz plate becomes thinner and the mechanical strength is reduced. It is common to set a small value.
In a VCXO (voltage controlled crystal oscillator), the external size of the crystal diaphragm changes due to the relationship between load capacitance characteristics.
That is, although the frequency-load capacitance characteristic changes depending on the size of the excitation electrode formed on the crystal plate, the change amount becomes larger as the frequency becomes higher, and the change may exceed the specified value. For this reason, when the frequency is increased, the size of the electrode is reduced, and accordingly, the outer size of the quartz diaphragm is also reduced. As described above, the external size of a quartz diaphragm generally differs depending on the required specifications.

[0004]

Problems to be Solved by the Invention
In the configuration disclosed in the above publication, there is no disclosure of a configuration for accommodating the size of the external size of such a piezoelectric vibrating plate. Even in this case, there is a possibility that the vibration region is obstructed or a short circuit accident occurs. That is, excitation electrodes are formed on the front and back of the piezoelectric vibration plate. However, when a large-sized piezoelectric vibration plate is used, the holding electrode comes into contact with the excitation electrode, thereby obstructing the vibration region or causing a short circuit between the electrodes. May have occurred.

A package corresponding to the change in the outer dimensions of the crystal diaphragm is disclosed in, for example, Japanese Utility Model Laid-Open No. 7-16422. In Japanese Utility Model Application Laid-Open No. 7-16422, holding supports made of a thin metal piece bent in a step shape are arranged to face each other, and by appropriately selecting this step portion, two types of elements having different external sizes can be mounted. I have.
However, the configuration having the holding support has a disadvantage that the space is inevitably increased and is not suitable for ultra-miniaturization.

It is considered that the above-mentioned stepped portion can be formed by a ceramic laminating technique. However, in the current ceramic laminating technique, the minimum thickness of a single layer is 100 μm, and the thickness of a thinner layer is more than 100 μm. Was difficult and expensive to obtain.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a package for a piezoelectric vibration device and a piezoelectric oscillator which can be reduced in size and height and in which piezoelectric vibration plates having different external sizes can be mounted. It is intended to do so.

[0008]

According to the present invention, there is provided a package for a piezoelectric vibrating device having a mounting portion for supporting a piezoelectric vibrating plate on which excitation electrodes are formed and joining with a conductive joining material. The mounting portion is made of a metal film and has a plurality of height regions, and a low mounting portion is provided at the center of the package and a high mounting portion is provided at the end of the package. The feature is that the mounting part to be supported can be selected according to the size.

According to each of the above structures, since the height portion is provided in the mounting portion made of the metal film, it is possible to mount a plurality of sizes of piezoelectric vibration plates without using a special support member. When a large-sized piezoelectric vibrating plate is used, by mounting the piezoelectric vibrating plate on the high mounting portion, the excitation electrodes formed on the piezoelectric vibrating plate are not short-circuited and the vibrating region is not obstructed. Further, since the height region is formed in the mounting portion, a required amount of the conductive bonding material can be retained in the bonding region, and the bonding strength can be improved.

In particular, the thickness of a metallized layer, for example, a tungsten metallized layer can be reduced to about 15 microns, and a very thin piezoelectric vibrating plate of about several tens microns corresponding to a recent increase in frequency is mounted. Thus, it is possible to obtain a low mounting portion and a high mounting portion suitable for the above. The metallized layer of tungsten or the like can be formed simultaneously when the ceramic package is laminated and fired.

According to a second aspect of the present invention, the piezoelectric vibrating plate has a rectangular shape, and the mounting portions are arranged in parallel on one short side of the piezoelectric vibrating plate, and the piezoelectric vibrating plate is disposed on the other short side. An auxiliary mounting portion for stabilizing the support of the piezoelectric vibrating plate may be formed, and the auxiliary mounting portion may have a plurality of height regions corresponding to the outer size of the piezoelectric diaphragm.

According to the second aspect, when the rectangular-shaped piezoelectric vibrating plate is cantilevered, a plurality of height regions are provided on the free end side, so that piezoelectric vibrating plates having different sizes are provided. Can be stably supported.

As a specific constituent material, for example, as described in claim 3, the package is made of ceramic such as alumina, and the mounting portion is formed of a plurality of metal layers.
The lowermost layer may be made of tungsten or molybdenum, and the uppermost layer may be made of gold or silver or a gold or silver alloy layer. It should be noted that an intermediate layer made of nickel or the like may be provided between the lowermost layer and the uppermost layer.

According to the third aspect, the lowermost layer of tungsten or molybdenum can be fired simultaneously with the ceramic, and the uppermost layer is made of gold or silver or a gold or silver alloy layer, thereby improving the bonding property with the conductive bonding material. Can be improved.

According to a fourth aspect of the present invention, the thickness of the lowermost layer of the mounting portion is greater in the higher mounting portion than in the lower mounting portion, and the other layers are substantially the same in the lower mounting portion and the higher mounting portion. It is configured to have a thickness. The thickness of the lowermost layer can be adjusted by changing the number of times of thick-film printing of paste-like tungsten metallization. For example, by first printing a thick film of tungsten metallization on the mounting portion forming region, and then printing a thick film of tungsten metallization with a small area on the upper part thereof, it is possible to very easily make the lowermost layer higher or lower.

According to the fourth aspect, the thickness of only the lowermost layer is changed during firing of the ceramic, and the other layers are made to have the same thickness by, for example, a normal electrolytic plating method, so that the height of the mounting portion can be extremely easily adjusted. Can be formed.

As an example of using the piezoelectric vibration device package, a piezoelectric oscillator in which a piezoelectric vibration plate on which excitation electrodes are formed and necessary circuit elements are housed in a piezoelectric vibration device package as described in claim 5 will be described. be able to.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of a crystal oscillator showing an embodiment of the present invention, and FIGS. 2 and 3 show a case where a large crystal vibration plate (piezoelectric vibration plate) is used in FIG. 1. FIG. FIG. 3 is a plan view before the hermetic sealing, and FIG. 3 is a plan view before the hermetic sealing. FIGS. 4 and 5 show a case where a small quartz-crystal vibrating plate (piezoelectric vibrating plate) is used in FIG. 1. FIG. 4 is an internal cross-sectional view in a state where the metal lid is hermetically sealed, and FIG. It is a top view before stopping. FIG. 6 is a view showing an electrode film configuration of the mounting portion.

The crystal oscillator is a ceramic package 1
And the IC 33 and the quartz vibrating plate 3 stored in the package, and the metal lid 2 for hermetically sealing the package.

The ceramic package 1 comprises a package body 10 mainly made of ceramics such as alumina and a metal seal portion 11, and has a storage portion 12 which is opened upward as a whole. The metal seal part 11 is provided in the opening.
Are formed in the storage portion 12, and a two-stage recess, that is, a lower lower recess 12a and an upper recess 12b above the lower recess 12a are formed. An electrode pad (not shown) is formed in the lower concave portion 12a, and the IC 33 is flip-chip mounted on the electrode pad. The IC may be connected to the package by wire bonding. The mounting portion 1 made of a metal film is provided at one end in the package longitudinal direction in the upper concave portion 12b.
4 and 15 are formed, and on the other side, an auxiliary mounting portion 13 made of a metal film is formed. A crystal vibrating plate 3 to be described later is cantilevered by these mounting portions, and is electrically connected by a conductive bonding material Z such as a paste adhesive or a solder to which a conductive material is added. In addition, the other end of the crystal diaphragm is auxiliary supported by the auxiliary mounting portion.

The mounting portions 14 and 15 are electrically connected to the IC 33 by predetermined electrode wiring, and the crystal oscillation plate 3 and the IC 33 constitute a crystal oscillation circuit. The mounting portions 14 and 15 have regions of a plurality of heights, have low mounting portions 141 and 151 on the package center side, and have high mounting portions 142 and 152 on the package end side. . These lower mounting portions 141 and 151 and higher mounting portion 14
In the formation of 2,152, the required height is obtained by adjusting the number of metallized layers to be simultaneously fired at the time of firing the ceramic package. For example, as shown in FIG. 6, a tungsten layer 14a is used as a metallization layer, one layer is formed in the lower mounting portion, and two or more layers are formed in the higher mounting portion. Nickel-plated 14b and gold-plated 14c with the same thickness on both the low and high mounting parts
Are formed in order. Thereby, the lowermost tungsten layer 1 is formed.
Only the mounting portion 4a can be made thicker. The auxiliary mounting section also has a low mounting section and a high mounting section, and employs the same configuration as the above mounting section. In addition,
Since the auxiliary mounting portion does not contribute to electrode connection, there is no practical problem even if nickel plating and gold plating are not formed.
The lower mounting part and the upper mounting part of these mounting parts and auxiliary mounting parts are set at almost the same height, respectively, to support mounting of multiple sizes of crystal diaphragms, and to prevent inclination when mounting a crystal diaphragm I have. The height difference between the low mounting portion and the high mounting portion depends on the frequency, that is, the thickness of the quartz plate.
It may be about 30 microns.

FIGS. 2 and 3 show a large-sized quartz vibrating plate 3.
FIG. 4 is a diagram showing a case where A is mounted. The crystal vibrating plate 3A is mounted in a suspended state on the high mounting portions 142 and 152 and the high mounting portion 132 of the auxiliary mounting portion, and is cantilevered by the high mounting portions 142 and 152 by the conductive bonding material Z. With the configuration having the concave and convex portions in which the high mounting portion and the low mounting portion are formed, the surface tension is easily generated in the conductive bonding material Z, and the supporting strength is improved.

FIGS. 4 and 5 show a small-sized quartz vibrating plate 3.
FIG. 6 is a diagram showing a case where B is mounted. The crystal vibration plate 3B is mounted on the lower mounting portions 141 and 151 and the lower mounting portion 131 of the auxiliary mounting portion in a state of being bridged, and is cantilevered by the lower mounting portions 141 and 151 by the conductive bonding material Z. Since the configuration is such that the conductive mounting material Z is more likely to accumulate and the surface tension is more likely to be generated, the support strength is improved, since the lower mounting portion at the mounting position is located behind the high mounting portion.

Castellations 1a, 1b, 1c and 1d are provided on the side surfaces of the ceramic package, and lead-out electrodes E1, E2, E3 and E4 are formed on the inside of the castellation and on the bottom surface of the package, respectively. The output terminal, the power supply terminal, and the ground terminal of the crystal oscillation circuit composed of the element and the IC are drawn out correspondingly.

The quartz oscillator 3 is formed of a rectangular AT-cut quartz plate, and the excitation electrodes 31 and 32 and the extraction electrodes 311 and 321 (321 not shown) are formed on the front and back surfaces by thin film forming means such as a vacuum evaporation method. Is formed.

The metal cover 2 has a structure in which a metal plate such as Kovar is plated with nickel on the front and back surfaces thereof, and is joined to the metal seal portion 11 around the opening of the ceramic package by means of seam welding or the like. Seal tightly. In addition, the metal seal part 11 is electrically connected to the ground terminal, and has an electromagnetic shield configuration with a metal lid.

The present invention is not limited to the above embodiment, but can be applied to other piezoelectric vibration devices. For example, as shown in FIGS. 7 and 8, it is also possible to apply the present invention to a surface-mount type crystal unit. FIG. 7 is an internal cross-sectional view of a state where a large quartz plate is used and hermetically sealed, and FIG. 8 is an internal cross-sectional view of a state where a small quartz plate is used and hermetically sealed. In the present embodiment, the ceramic package 4 has a flat plate configuration in which necessary wiring is provided, and uses an inverted concave metal lid 5 hermetically joined to the periphery of the ceramic package 4. In addition, the support structure of the quartz vibrating plate is configured to have both ends in the longitudinal direction, and mounting portions 44 and 45 are formed at both ends. Accordingly, extraction electrodes 311 and 321 extending from the excitation electrodes 31 and 32 extend to both ends in the longitudinal direction.

As shown in FIG. 7, the large-sized quartz vibrating plate 3A is mounted on the high mounting portions 442 and 452, and the small-sized quartz vibrating plate 3B is mounted on the high mounting portions 441 and 451 as shown in FIG. It is mounted, and it is possible to selectively mount different crystal sizes of large and small sizes. Also in this embodiment, the structure in which the upper mounting portion and the lower mounting portion are formed easily causes surface tension in the conductive bonding material, and improves the support strength.

It is to be noted that the plurality of height regions formed on the mounting portion may have not only two levels but also higher levels as described above. The uppermost layer may be not only a gold layer but also a silver layer, or an alloy layer made of gold or silver.

[0030]

According to the present invention, since a height portion is provided in a mounting portion made of a metal film, a plurality of sizes of piezoelectric vibration plates can be mounted without using a special support member. Good electrical characteristics can be obtained without hindering short-circuiting of electrodes or vibrating regions. In addition, since the high and low regions are formed in the mounting portion, the surface area increases, and a necessary amount of the conductive bonding material can stay in the bonding region due to surface tension or the like, and the bonding strength can be improved. In addition, lamination with a metal film can make one layer relatively thin. Therefore, it is possible to obtain a package for a piezoelectric vibrating device that has good electrical characteristics, can be reduced in size and height, and can be mounted with a piezoelectric vibrating plate having a different external size.

According to claim 2, in addition to the above effects,
Since the cantilever support can secure a wider vibration area of the piezoelectric vibrating plate than the cantilever support, a more compact piezoelectric vibration device can be obtained. When a rectangular-shaped piezoelectric vibrating plate is cantilevered, a plurality of height regions are provided not only on the fixed end side but also on the free end side so that piezoelectric vibrating plates of different sizes can be supported. Stable support can be provided. Therefore, a piezoelectric vibrating device having good electric characteristics can be obtained even if the device is miniaturized.

According to claim 3, in addition to the above effects,
The lowermost layer of tungsten or molybdenum can be fired simultaneously with the ceramic, and the uppermost layer can be made of gold or silver or a gold or silver alloy layer to improve the bondability with the conductive bonding material.

According to claim 4, in addition to the above effects,
By changing the thickness of only the lowermost layer at the time of firing the ceramic and setting the other layers to the same thickness by, for example, a normal electrolytic plating method, the height of the mounting portion can be formed very easily.

According to the fifth aspect, it is possible to obtain a piezoelectric oscillator which can be reduced in size and on which piezoelectric vibrating plates having different external sizes can be mounted.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment.

FIG. 2 is an internal cross-sectional view of a state where components are assembled using a large piezoelectric diaphragm in FIG. 1;

FIG. 3 is a plan view before hermetic sealing when a large piezoelectric vibration plate is used in FIG. 1;

FIG. 4 is an internal cross-sectional view of a state where components are assembled using a small piezoelectric diaphragm in FIG. 1;

FIG. 5 is a plan view before airtight sealing when a small piezoelectric vibration plate is used in FIG. 1;

FIG. 6 is a diagram showing an electrode film configuration of a mounting unit.

FIG. 7 is an internal cross-sectional view showing another embodiment.

FIG. 8 is an internal cross-sectional view showing another embodiment.

[Explanation of symbols]

 1, 4 Ceramic package 14, 15, 44, 45 Mounting part 13 Auxiliary mounting part 141, 151, 131, 441, 451 Low mounting part 142, 152, 132, 442, 452 High mounting part 10 Package body 11 Metal layer 2 Lid 21 Metal layer 3 Quartz diaphragm (piezoelectric diaphragm) 33 IC

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H03H 9/19 H01L 41/08 C

Claims (5)

[Claims] 1. A package for a piezoelectric vibration device having a mounting portion that supports a piezoelectric vibration plate on which an excitation electrode is formed and is joined by a conductive bonding material, wherein the mounting portion is made of a metal film and has a plurality of heights. The lower mounting portion is provided at the center of the package, and the upper mounting portion is provided at the end of the package, and the mounting portion to be supported according to the outer size of the piezoelectric diaphragm can be selected. Package for vibration device. 2. The piezoelectric vibrating plate has a rectangular shape, and the mounting portions are arranged in parallel in one short side direction of the piezoelectric vibrating plate, and the other short side is an auxiliary member for stabilizing the support of the piezoelectric vibrating plate. 2. The package for a piezoelectric vibration device according to claim 1, wherein a mounting portion is formed, and the auxiliary mounting portion has a plurality of height regions corresponding to an outer size of the piezoelectric vibration plate. 3. The package according to claim 1, wherein the package is made of ceramic, the mounting portion is made of a plurality of metal layers, the lowermost layer is made of tungsten or molybdenum, and the uppermost layer is made of gold or silver or a gold or silver alloy layer. The package for a piezoelectric vibration device according to claim 1 or 2, wherein 4. The lowermost layer of the mounting portion has a thickness higher in a higher mounting portion than in a lower mounting portion, and the other layers have substantially the same thickness in both the lower mounting portion and the higher mounting portion. The package for a piezoelectric vibration device according to claim 3. 5. A piezoelectric oscillator, wherein a piezoelectric vibration plate on which excitation electrodes are formed and necessary circuit elements are housed in the piezoelectric vibration device package according to any one of claims 1 to 4.