JP3937437B2 - Piezoelectric vibration device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a holding structure for a piezoelectric vibration device such as a crystal resonator, and improves the structure of a support for holding a piezoelectric vibration plate.
[0002]
[Prior art]
Examples of the piezoelectric vibration device include a crystal resonator, a crystal filter, a crystal oscillator, and the like. For example, a crystal resonator is widely used as a reference source for frequency and time because it has excellent resonance characteristics. In these piezoelectric vibration devices, a metal thin film electrode is formed on the surface of a crystal vibration plate (piezoelectric vibration plate), and the metal thin film electrode is hermetically sealed by a package body in order to protect the metal thin film electrode from the outside air.
[0003]
Conventionally, as disclosed in Patent Document 1, a pair of metal lead terminals are implanted in a metal base via an insulating material such as glass, and a pair of metals is provided in an inner lead portion of the metal lead terminal. Flat support members are attached to face each other. The quartz diaphragm is, for example, an AT-cut quartz diaphragm that vibrates through a thickness, and an excitation electrode and an extraction electrode from each excitation electrode are formed on the front and back surfaces. A quartz diaphragm is mounted on the support, and is electrically and mechanically connected by a conductive bonding material. The metal base is covered with a metal lid, and these are air-bonded to each other by a technique such as resistance welding. The structure is hermetically sealed.
[0004]
In Patent Document 1, an airtight terminal type in which a small crystal diaphragm that is widely used for a surface-mounted crystal resonator using a ceramic container is hermetically sealed by covering a metal base with a lead terminal with a metal cap. We have proposed a support structure that can also be applied to crystal units.
[0005]
[Patent Document 1]
JP 2001-308669 A [0006]
[Problems to be solved by the invention]
However, the configuration of Patent Document 1 has the following problems and is not practical.
[0007]
When welding to the lead connection part of the support to the upper part on the inner lead side of the lead terminal, the position of the upper part of the inner lead is difficult to recognize, and the center of gravity is biased only in the direction in which the lead terminal is close. , Easy to be deflected.
[0008]
In addition, the support itself is difficult to position in order to suppress displacement, inclination, and deflection.
[0009]
For this reason, the piezoelectric diaphragm is mounted with the support displaced, and when the electromechanical joining is performed with the conductive bonding material, the piezoelectric diaphragm is distorted, and the electrical characteristics of the piezoelectric vibrator are adversely affected.
[0010]
Furthermore, if the support surface is placed close to the top surface of the base to reduce the height, a jig cannot be inserted between the support and the top surface of the base, so the support cannot be positioned and the support is separated from the lead frame. The support cannot be welded and attached to the lead terminal in a stable state.
[0011]
In addition, since it is difficult to distinguish between the lead connecting portion of the support and the element mounting portion, the positional relationship between the support and the piezoelectric diaphragm is difficult to recognize, and the piezoelectric diaphragm is likely to be mounted on the support.
[0012]
Furthermore, if the width dimension of the element mounting portion is substantially the same as the width dimension of the lead connecting portion of the support, the support is liable to be adversely affected by the inclination or displacement of the support depending on the welding state (joined state) with the lead terminal.
[0013]
The present invention has been made in order to solve the above-mentioned problems, and not only has a structure in which a small crystal unit can be applied, but also improves the bonding accuracy and bonding stability of the support to the lead terminal, and the piezoelectric to the support. An object of the present invention is to provide a more reliable piezoelectric vibration device capable of simultaneously improving the mounting accuracy and mounting stability of a diaphragm.
[0014]
[Means for Solving the Problems]
Therefore, in the present invention, as shown in claim 1, a metal base in which at least two metal lead terminals are implanted through an insulating material, and a flat plate welded to the inner side of the metal lead terminal A metal plate, a piezoelectric vibration plate mounted in the same direction as the plate surface of the metal support, and formed with an excitation electrode to be electrically connected, and the piezoelectric vibration plate is hermetically covered. A piezoelectric device comprising a flange of the base and a metal cap having a flange that is resistance-welded or cold-welded, wherein the metal support is connected to the lead terminal, and the lead connecting portion. Extending in a direction close to each other and having a narrow width with respect to the lead connection part, and extending in a direction separating from the lead connection part through the rising part, And having a narrow positioning portion with respect to the lead connecting portions.
[0015]
According to a second aspect of the present invention, in the above-described configuration, the lead connection portion includes a welding region joined to a lead terminal on a straight line connecting a center point of the element mounting portion and a center point of the positioning portion. And a notch is formed, and the notch is disposed adjacent to the welding region.
[0016]
According to a third aspect of the present invention, in the above-described configuration, the tip of the inner lead of the lead terminal has a nail head shape.
[0017]
According to a fourth aspect of the present invention, in the above configuration, Ag flash plating is applied to the surface of the element mounting portion.
[0018]
According to a fifth aspect of the present invention, in the above-described configuration, the surface of the element mounting portion is roughened.
[0019]
【The invention's effect】
According to the first aspect of the present invention, in a hermetic terminal type piezoelectric vibration device in which a metal base with a lead terminal with high reliability of hermetic sealing is covered with a metal cap and hermetically sealed, the piezoelectric vibration narrower than the interval between the lead terminals. A board can be mounted. Therefore, a small piezoelectric diaphragm that is widely used for surface-mount type piezoelectric vibrating devices can be applied to an airtight terminal type piezoelectric vibrating device, which can greatly contribute to cost reduction.
[0020]
In addition, since the element mounting portion and the positioning portion extend in a direction to be separated from each other via the lead connection portion, the extension direction and position of the element mounting portion can be recognized by the positioning portion. For this reason, when the support is welded to the lead terminal, not only the directionality and position accuracy of the element mounting part is improved by the positioning part, but also the positional connection between the lead connecting part and the element mounting part is fixed by fixing the positioning part. It can be welded very stably in the lost state.
[0021]
Furthermore, since the positioning part is formed from the lead connection part through the rising part, even when the lead connection part and the element mounting part on the same plane are positioned as low as possible, it is between the support positioning part and the upper surface of the base. Since the jig can be inserted, the positioning of the support and the detachment of the support from the lead frame can be performed very easily. This configuration can contribute to a reduction in height and size.
[0022]
In addition, since the element mounting part and positioning part are formed narrower than the lead connection part, each region can be identified, and the positional relationship between the support and the lead terminal and the positional relationship between the support and the piezoelectric diaphragm are recognized. It's easy to do. Therefore, the image recognition technology not only improves the positional accuracy of the lead connection when welding the support to the lead terminal, but also improves the positional accuracy of the piezoelectric vibration plate when mounting the piezoelectric vibration plate on the support. Let
[0023]
Furthermore, since the element mounting portion is formed narrower than the lead connection portion, a dispersion effect is generated between the lead connection portion and the element mounting portion, and the impact can be reduced. Due to the welded state (joined state), it is difficult to be adversely affected by tilting or shifting of the support of the element mounting portion.
[0024]
According to the present invention, not only a structure capable of applying a small crystal unit is adopted, but also the bonding accuracy and bonding stability of the support to the lead terminal are improved, and the mounting accuracy and mounting stability of the piezoelectric diaphragm to the support are simultaneously increased. It is possible to provide a piezoelectric vibration device with higher reliability that can be achieved.
[0025]
According to the second aspect of the present invention, in addition to the above-described effects, a welding region and a notch are formed on a straight line connecting a center point of the element mounting portion and a center point of the positioning portion, and the welding is performed. Since the notch is disposed adjacent to the area, it is easy to align the position of the welding area depending on the position of the positioning part or the position of the notch when the support is welded to the lead terminal. At the same time, the direction of the element mounting portion can be easily matched, so that a more accurate support can be attached. In addition, a notch is formed in the vicinity of the welding region on a straight line connecting the center point of the element mounting portion and the center point of the positioning portion, so that the positioning portion is connected to the element mounting portion, or from the lead connection portion. The influence of external impact on the element mounting portion can be further alleviated.
[0026]
According to the third aspect of the present invention, in addition to the above-mentioned effects, the tip of the inner lead of the lead terminal has a nail head shape, so that when the support is mounted on the lead terminal, the support can be stably mounted horizontally without tilting. The reliability when welding lead terminals is dramatically improved. Since the welding area is expanded, the bonding strength is improved. In addition, since the tip of the inner lead of the lead terminal has a nail head shape, the vibration amplitude of the support due to the impact is reduced, leading to an improvement in impact resistance.
[0027]
According to the fourth aspect of the invention, in addition to the above-described effects, the surface of the element mounting portion is subjected to Ag flash plating, so that the bonding interface is improved, and the conductive bonding material between the piezoelectric diaphragm and the support is used. Electromechanical joint strength is improved, leading to improved conduction stability and impact resistance of the piezoelectric vibration device.
[0028]
According to claim 5, in addition to the above-described effects, the surface of the element mounting portion is roughened, so that the bonding interface is improved and the conductive bonding material between the piezoelectric diaphragm and the support is used. Electromechanical joint strength is improved, leading to improved conduction stability and impact resistance of the piezoelectric vibration device.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings, taking a crystal resonator as an example. 1 is an exploded perspective view showing an embodiment of the present invention, FIG. 2 is an internal sectional view of the assembled state of FIG. 1, and FIG. 3 is a plan view of the base of FIG.
[0030]
The piezoelectric diaphragm 2 is made of an AT cut quartz diaphragm and is processed into a rectangular shape. Excitation electrodes 21 and 22 (the back surface 22 is not shown) and extraction electrodes 21a and 22a are provided on the front and back surfaces by means such as vacuum deposition. In addition, the extraction electrode is made to wrap around the opposite main surface in order to ensure electrical connection described later.
[0031]
The base 1 as a whole has a low-profile long cylindrical shape, and has a structure in which metal lead terminals 11 and 12 are planted through a base body 10 mainly including a metal shell, and an insulating glass G is used as a base body. These metal lead terminals 11 and 12 are electrically independent by being filled in a part. A circumferential flange 10a is integrally provided at the lower peripheral portion of the base body. In addition, although not shown in figure, the circumferential protrusion part (projection) is integrally formed in the flange 10a.
[0032]
The lead terminals 11 and 12 have a long and narrow cylindrical shape, and the tip portions 11a and 12a on the inner side of the upper portion of the base are formed in a wide and flat nail head shape. Metal supports 13 and 14, which will be described later, are attached to the tip of the inner lead so as to face each other by a welding method (laser welding, spot welding, etc.).
[0033]
The metal supports 13 and 14 are made of a metal flat plate such as a Cu—Ni—Zn alloy, SUS, white, Kovar, phosphor bronze, 42 alloy, etc., and wide lead connecting portions 131 and 141 joined to the lead terminals. The narrow element mounting portions 132 and 142 extending from the lead connection portion in a direction close to each other, and the narrow positioning portions 134 extending from the lead connection portion through the rising portions 133 and 143 to be separated from each other. , 144. Ag flash plating M is applied to the surface of the element mounting portion. Instead of this Ag flash plating, gold plating or nickel plating may be applied. Furthermore, instead of these metal platings, the surface of the element mounting portion is roughened to increase the surface area of the element mounting portion, improve the bonding interface with the conductive bonding material described later, and increase the bonding strength. improves.
[0034]
The lead connection portions 131 and 141 include welding regions 1311 and 1411 to be joined to lead terminals on a straight line connecting the center point of the element mounting portion and the center point of the positioning portion, and a part of the welding region. Circumferentially formed semicircular cutouts 1312, 1412 are formed, and the connection region from the lead connection portions 131, 141 to the positioning portions 134, 144 is a surface so that the width is gradually narrowed. The taking parts 1313 and 1413 are formed. The chamfered portion is not limited to the curved R surface, and may be a straight C surface.
[0035]
In this embodiment, since the semicircular cutout is provided in the weld area, it becomes clear that the weld area of the lead terminal exists in the center of the cutout, and only the impact resistance is improved. It also functions as a mark for specifying the welding region.
[0036]
Further, the element mounting portion of the support of the present embodiment is located at the center in the width direction of the piezoelectric diaphragm, and the width dimension W2 of the element mounting portion is 50% to 90% with respect to the width dimension W1 of the piezoelectric diaphragm. %, And it is difficult for the piezoelectric diaphragm plate mounted with the influence of the support inclination and variation joined to the lead terminal to be mounted.
[0037]
The metal cap 3 has a long cylindrical shape with an open bottom surface. The opening has a flange 31 corresponding to the flange 10a of the base, and is hermetically sealed by resistance welding to the base 1. Done.
[0038]
Then, the piezoelectric diaphragm 2 is mounted on the support element mounting portions 132 and 142, and the element mounting portions 132 and 142 and the extraction electrodes 11 a and 12 a are conductively bonded with the conductive bonding material S. The conductive bonding material S is preferably a silicon-based or urethane-based adhesive that is relatively elastic.
[0039]
Then, after performing necessary treatment such as annealing, the base is covered with a cap, and although not shown, the welding electrode body is brought into contact with both flanges, and energized while applying pressure to both to perform resistance welding. The hermetic sealing is completed.
[0040]
-Other embodiments-
Not only the support shape of the said embodiment but a structure as shown in FIG. 4 may be sufficient. In the drawing, only the metal support 14 is illustrated, and parts having the same configuration are denoted by the same reference numerals and part of the description is omitted.
[0041]
In FIG. 4A, the metal support 14 of this figure is formed with a substantially U-shaped notch 1412 provided around a part of the welding region on the element mounting portion side as compared with the above embodiment. On the other hand, a chamfered portion 1413 (linear C) is formed so that the width gradually decreases from the lead connecting portion 141 to the positioning portion 144 and from the lead connecting portion 141 to the element mounting portion 142. The surface is formed, and instead of Ag flash plating, the surface of the element mounting portion is subjected to a rough surface processing (for example, a rimple processing) R. With this configuration, external impact on the piezoelectric diaphragm can be further alleviated. In addition, the bonding interface can be improved and the bonding strength can be improved at a lower cost than Ag flash plating.
[0042]
FIG. 4B shows that the metal support 14 shown in this figure has a step-like rising portion as compared with the above embodiment, and the positioning portion 144 is inclined to rise, and at least part of the welding region. The difference is that four cutouts 1412, 1412, and 1412 are formed around the periphery, and a positioning piece 1414 of a piezoelectric diaphragm is formed on the element mounting portion side of the lead connection portion 141. . In this configuration, since the height of the rising can be suppressed, it is advantageous in reducing the height, and the mounting stability of the piezoelectric diaphragm by the positioning piece is further improved.
[0043]
In the above-described metal support of the present invention, since only the lead connection portion is formed wider than the element mounting portion and the positioning portion, the center of gravity of the metal support is formed in accordance with the welding region of the lead connection portion. This makes it easier to mount a support with better stability.
[0044]
In addition, although the crystal resonator was illustrated as an example of the piezoelectric vibration device of the present invention, a crystal filter, a crystal oscillator, or the like may be used. In addition, the tip of the inner lead of the lead terminal is exemplified only in the shape of a nail head, but the present invention can also be applied to a normal inner lead shape.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing an embodiment of the present invention.
2 is an internal cross-sectional view of the assembled state of FIG. 1;
FIG. 3 is a plan view of the base of FIG. 1;
FIG. 4 is a perspective view of a support showing another embodiment according to the present invention.
[Explanation of symbols]
1 Base 10 Base body 11, 12 Lead terminal 13, 14 Support 2 Piezoelectric diaphragm (crystal diaphragm)
3 cap

Claims (5)

A metal base in which at least two metal lead terminals are embedded through an insulating material, a flat metal support welded to the inner side of the metal lead terminal, and the same direction as the plate surface of the metal support A piezoelectric diaphragm on which an excitation electrode that is mounted and electrically connected is formed, and a flange that is hermetically covered with the piezoelectric diaphragm and is resistance-welded or cold-welded to the flange of the base. A piezoelectric device comprising a metal cap having
The metal support includes a lead connecting portion joined to the lead terminal, an element mounting portion extending in a direction close to the lead connecting portion and narrow with respect to the lead connecting portion, and the lead connecting portion. A piezoelectric vibration device characterized by having a positioning portion that extends in a direction to be separated from each other via a rising portion and is narrow with respect to a lead connection portion. The lead connection portion is formed with a weld region and a cutout portion joined to a lead terminal on a straight line connecting a center point of the element mounting portion and a center point of the positioning portion, and the cutout portion is formed in the weld region. The piezoelectric vibration device according to claim 1, wherein the piezoelectric vibration devices are arranged adjacent to each other. The piezoelectric vibration device according to claim 1, wherein a tip portion of the inner lead of the lead terminal has a nail head shape. The piezoelectric vibration device according to claim 1, wherein Ag flash plating is applied to a surface of the element mounting portion. The piezoelectric vibration device according to claim 1, wherein the surface of the element mounting portion is roughened.

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