JP2005217801A - Piezoelectric transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric transducer that can be handled easily and can cope with the miniaturization of an entire structure relatively easily. <P>SOLUTION: In the piezoelectric transducer, a plurality of external terminals 3 including a ground terminal 3a and a recess 1a are provided on the lower surface and the upper surface of a container 1, respectively, a piezoelectric element 5 is accommodated in the recess 1a, and a metal lid 8 for blocking the opening of the recess 1a is attached onto the upper surface of the container 1. In the piezoelectric transducer, the lid 8 and the ground terminal 3a are electrically connected via a ground wiring conductor 6 deposited on the inner surface of the recess of the container 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a piezoelectric vibrator such as a quartz vibrator used in electronic equipment such as portable communication equipment and electronic computers.

  Conventionally, crystal resonators have been used in electronic devices such as portable communication devices and electronic computers.

  As such a conventional crystal resonator, for example, as shown in FIG. 3, a concave portion 22 is formed on the upper surface of a container body 21 made of alumina ceramic or the like, and a quartz resonator element 23 is mounted and accommodated in the concave portion 22. There is known a structure in which a metal lid 24 is attached and joined to the upper surface of the container body 21 so as to close the opening of the recess 22 (see, for example, Patent Document 1).

  The lid body 24 is mounted and fixed on the upper surface of the container body 21 via a metal sheet or the like, and is joined to the upper surface of the container body 21 by conventionally known resistance welding or the like. Thereby, the region surrounded by the inner surface of the recess 22 and the lower surface of the lid 24 is hermetically sealed.

  In the above-described conventional crystal resonator, the lid body 24 is usually electrically connected to the ground terminal 27 on the lower surface of the container body via the via-hole conductor 26 and the like inside the container body. By holding the lid 24 at the ground potential, the crystal resonator element 23 is protected from unnecessary electric action such as noise.

When such a crystal resonator is applied with a varying voltage from the outside between the vibration electrodes of the crystal resonator element 23 via an input / output terminal (input terminal / output terminal) provided on the lower surface of the container body 21, the crystal resonator element The thickness shear vibration is generated at a predetermined frequency corresponding to the characteristic of the frequency 23, and a predetermined oscillation signal is generated and output by an external oscillation circuit based on the frequency, thereby functioning as a crystal resonator. The obtained oscillation signal is used as a clock signal (reference signal) in an electronic device such as a portable communication device.
JP 2001-274649 A

  Incidentally, in the above-described conventional crystal resonator, the lid body 24 and the ground terminal 27 are electrically connected via the via-hole conductor 26 and the like inside the container body. The part led out to the upper surface of the container is embedded in the side wall of the container body 21 (the part between the inner wall of the recess and the outer wall of the container body). Therefore, when the thickness of the side wall portion described above is reduced along with the recent miniaturization of the crystal unit, the diameter of the via hole conductor 26 embedded in the side wall portion is also reduced. As a result, the upper end of the via hole conductor 26 is reduced. There is a drawback that it is difficult to reliably establish conduction with a metal sheet or the like on the upper surface of the container body 21 from which is exposed.

  Therefore, in order to eliminate the above-described drawbacks, a belt-like ground wiring conductor is attached from the upper end to the lower end of the outer wall surface of the container instead of the via hole conductor 26 described above, and the lid body 24 and the ground terminal 27 are interposed via the ground wiring conductor. Can be electrically connected to each other.

  However, when the ground wiring conductor is attached to the outer wall surface of the container body 21, a part of the melted solder when the crystal resonator is mounted on an external wiring substrate such as a mother board by soldering or the like becomes the ground wiring conductor. Adhering causes a short circuit, or the molten solder crawls up to the vicinity of the lid body 26 through the ground wiring conductor, and mixes with a bonding material such as Au—Sn, thereby significantly increasing the bonding strength of the lid body 26. There is a risk that it may be lowered, and there is a drawback that the handling of the crystal resonator is not easy.

  The present invention has been devised in view of the above-mentioned drawbacks, and an object of the present invention is to provide a piezoelectric vibrator that is easy to handle and can cope with the downsizing of the entire structure relatively easily.

  The piezoelectric vibrator of the present invention includes a plurality of external terminals including ground terminals on the lower surface of the container body, a recess on the upper surface, a piezoelectric vibration element accommodated in the recess, and the recess on the upper surface of the container body. In the piezoelectric vibrator formed by attaching a metal lid that closes the opening of the container, the lid and the ground terminal are electrically connected via a ground wiring conductor attached to the inner surface of the concave portion of the container body. It is characterized by being connected to.

  The piezoelectric vibrator of the present invention is characterized in that the ground wiring conductor is attached to the inner surface of a notch formed in a column shape from the opening of the recess to the bottom of the recess.

  Furthermore, the piezoelectric vibrator of the present invention is characterized in that the concave opening of the container body has a rectangular shape, and the notch is provided at a corner of the opening.

Still further, in the piezoelectric vibrator of the present invention, the container body has a rectangular shape and the notch has a substantially cylindrical shape, and the shortest distance D from the corner portion of the container body to the notch adjacent to the corner portion. And the thicknesses T ₁ and T ₂ of the side wall portion between the outer surface of the container body and the inner wall of the concave portion arranged on both sides of the corner portion satisfy both the relational expressions “D ≧ T ₁ ” and “D ≧ T ₂ ”. It is characterized by being set to.

  Furthermore, the piezoelectric vibrator of the present invention is characterized in that the piezoelectric vibration element is a crystal vibration element.

  According to the piezoelectric vibrator of the present invention, the ground wiring conductor is attached to the inner surface of the concave portion of the container body in which the piezoelectric vibration element is accommodated, and the metal lid and the container body on the container body are interposed via the ground wiring conductor. Since the ground terminal on the lower surface is electrically connected, the thickness of the side wall portion of the container body is affected by the thickness of the side wall portion of the container body even when the thickness of the side wall portion of the container body is reduced due to downsizing of the piezoelectric vibrator. Accordingly, the ground wiring conductor can be reliably connected to the bonding conductor on the upper surface of the container body, and the piezoelectric vibrator can be miniaturized.

  Moreover, according to the piezoelectric vibrator of the present invention, since the ground wiring conductor is attached to the inner surface of the concave portion of the container body, when mounting the piezoelectric vibrator on an external wiring board such as a mother board by soldering or the like, A part of the melted solder adheres to the ground wiring conductor to cause a short circuit, or the melted solder is mixed with a bonding material such as Au—Sn for joining the lid, thereby reducing the joint strength of the lid. Such a problem is eliminated, and a piezoelectric vibrator that is easy to handle can be obtained.

  According to the piezoelectric vibrator of the present invention, if the ground wiring conductor is attached to the inner surface of the notch formed in a column shape from the opening of the recess to the bottom of the recess, the piezoelectric vibration element is grounded in the recess. It is possible to effectively prevent a short circuit due to contact with the wiring conductor, and it is possible to maintain high productivity of the piezoelectric vibrator.

Furthermore, according to the piezoelectric vibrator of the present invention, the opening of the concave portion is formed in a rectangular shape, and the above-mentioned notch is provided in the inner corner of the inner surface of the concave portion where the thickness of the side wall portion is the thickest. The mechanical strength can be kept high, and the breakage of the container body due to the application of external force can be effectively prevented. In this case, the shortest distance D from the corner portion of the container body to the notch close to the corner portion is set to be larger than the thicknesses T ₁ and T _{2 of the} container body side wall portions arranged on both sides of the corner portion. By doing so, it is possible to more reliably prevent damage to the container body due to application of external force, and it is possible to maintain high reliability of the piezoelectric vibrator.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an embodiment in which the piezoelectric vibrator of the present invention is applied to a quartz crystal vibrator. The quartz crystal vibrator shown in the figure is roughly composed of a container body 1 and a quartz crystal as a piezoelectric vibrating element. The vibration element 5 and the lid 8 are configured.

  The container body 1 is formed, for example, by laminating a plurality of insulating layers made of a ceramic material such as alumina ceramics or glass-ceramics, and a concave portion 1a that opens in a rectangular shape in the central region on the upper surface thereof. However, an annular bonding conductor 9 surrounding the opening of the recess 1a is formed in the peripheral area, and a plurality of external terminals 3 including an input terminal, an output terminal, and a ground terminal 3a are provided on the lower surface.

  The container body 1 is for accommodating the crystal resonator element 5 inside, specifically, in the recess 1a. A pair of connection pads 2 are provided on the bottom surface of the recess 1a, and a circular shape is provided on the inner wall of the recess 1a. A columnar notch 4 is formed.

  The pair of connection pads 2 provided on the bottom surface of the recess 1a are electrically connected to the vibration electrode of the crystal resonator element 5 on the upper surface side through a conductive adhesive, and the conductors inside the container body on the lower surface side. It is electrically connected to the input / output terminal (input terminal / output terminal) via a pattern, a via-hole conductor or the like.

  On the other hand, the notches 4 provided on the inner wall of the recess 1a are provided at two corners of the four corners of the recess 1a, and are formed from the opening of the recess 1a to the bottom of the recess.

  A ground wiring conductor 6 is deposited and formed on the inner surface of the recess 1a facing the notch 4, and the upper end side of the ground wiring conductor 6 is electrically connected to the bonding conductor 9, and the lower end. The side is electrically connected to the ground terminal 3a on the lower surface of the container body via a via-hole conductor embedded below the bottom surface of the recess in the container body 1.

  Further, the bonding conductor 9 provided on the upper surface of the container body 1 is formed in an annular shape by a conductive material such as Au—Sn, Au—Ni, for example, and the surface of the bonding conductor 9 is described later. The seal ring 10 is joined.

  Furthermore, the plurality of external terminals 3 provided on the lower surface of the container body 1 are formed by conductive bonding such as soldering with the wiring of the external wiring board when the crystal resonator is mounted on the external wiring board such as a mother board. It functions as a terminal for electrical connection through a material.

  When the container body 1 is made of alumina ceramic, the external terminal 3, the connection pad 2, and the conductor pattern are formed on the surface of a ceramic green sheet obtained by adding and mixing a suitable organic solvent to a predetermined ceramic material powder. In addition, a conductive paste to be a via-hole conductor is applied by a conventionally known screen printing or the like into a through-hole previously punched by punching a ceramic green sheet or the like, and a plurality of such pastes are applied. After being laminated and press-molded, it is manufactured by firing at a high temperature. The depth of the notch 4 is set to a depth of 40 μm to 80 μm, for example, when the thickness of the side wall portion of the container body 1 (region between the inner wall surface of the recess and the outer wall surface of the container body) is 200 μm, The ground wiring conductor 6 provided so as to be in contact with the formation region is deposited and formed on the inner surface of the recess 1a by a conventionally known electrolytic plating method or the like.

  The quartz resonator element 5 accommodated in the recess 1a of the container body 1 has a pair of vibrating electrodes (not shown) on both main surfaces of a crystal piece having a thickness of 30 μm to 160 μm cut along a predetermined crystal axis. When the fluctuating voltage from the outside is applied to the crystal piece via the pair of vibrating electrodes, the thickness shear vibration is caused at a predetermined frequency.

  Such a quartz-crystal vibrating element 5 is obtained by electrically and mechanically connecting the vibrating electrodes attached to both main surfaces thereof and the corresponding connection pads 2 on the bottom surface of the recesses via the conductive adhesive 7. It is mounted on the bottom surface of the recess of the container body 1.

  Furthermore, a metal lid 8 is fixed to the upper surface of the container body 1 via a seal ring 10, whereby the lid 8 is interposed via the seal ring 10, the joining conductor 9 and the ground wiring conductor 6. And the ground terminal 3a on the lower surface of the container body is electrically connected. At the same time, the opening of the concave portion 1a is closed on the lower surface of the lid body 8, and the region in which the crystal resonator element 5 is accommodated is hermetically sealed.

  At this time, the lid 8 made of metal is electrically connected to the ground terminal 3a via the above-described ground wiring conductor 6 and the like, and the lid 8 is held at the ground potential when the crystal resonator is used. Therefore, the quartz resonator element 5 can be protected better than the unnecessary electrical action from the outside by the shielding action of the lid 8.

  In this case, since the ground wiring conductor 6 is attached to the inner surface of the concave portion of the container body 1, the container body 1 can be used even when the thickness of the side wall portion of the container body 1 is reduced as the quartz resonator element is downsized. 1 can be reliably connected by the ground wiring conductor 6 without being influenced by the thickness of the side wall of the container body 1, and the crystal resonator can be miniaturized. It becomes possible.

  Moreover, since the ground wiring conductor 6 is attached to the inner surface of the concave portion of the container body 1, a part of the melted solder is mounted when the crystal resonator is mounted on an external wiring board such as a mother board by soldering or the like. Are attached to the ground wiring conductor 6 to cause a short circuit, or the melted solder is mixed with a bonding material such as Au—Sn for bonding the lid body 8 to reduce the bonding strength of the lid body 8. There is also an advantage that a crystal resonator that can be easily handled can be obtained.

  Further, since the ground wiring conductor 6 is attached to the inner surface of the notch 4 formed in a column shape from the opening of the recess 1a to the bottom of the recess, the crystal resonator element 5 contacts the ground wiring conductor 6 in the recess 1a. Therefore, it is possible to effectively prevent the occurrence of a problem such as a short circuit, and it is possible to maintain high productivity of the crystal unit.

Furthermore, in this embodiment, since the notch 4 is provided at the inner corner of the inner surface of the recess where the thickness of the side wall of the container body 1 is the thickest, the container body 1 by providing the notch 4. It is possible to keep the mechanical strength of the container body 1 high, and to effectively prevent damage to the container body 1 due to the application of external force. In this respect, as a more preferable condition, the shortest distance D from the corner portion of the container body 1 to the notch 4 adjacent to the corner portion is set to the thickness T of the container body side wall portion disposed on both sides of the corner portion. _1, by setting larger than T _2, thereby more reliably prevent breakage of the container body 1 due to the application of external force, it is possible to maintain high reliability of the crystal oscillator.

  The lid 8 and the seal ring 10 are formed of a metal such as Kovar, 42 alloy, phosphor bronze, etc., respectively, and the seal ring 10 is made of a bonding material such as Au-Sn or Au-Ni. The lid body 8 is attached to the container body 1 by being joined to the joining conductor 9 on the top surface of the container body, and the lid body 8 employs a well-known seam welding (resistance welding) or the like. It is attached to the upper surface of the seal ring 10 by being bonded to the upper surface of the seal ring 10 via a bonding material such as Au—Ni.

  At this time, if the lid 8 is joined in an inert gas atmosphere such as nitrogen gas or argon gas, the space in which the crystal resonator element 5 is accommodated is filled with inert gas. It is possible to effectively prevent the vibration element 5 from being corroded or deteriorated by oxygen or moisture in the atmosphere. Therefore, it is preferable to perform the joining operation of the lid 8 in an inert gas atmosphere such as nitrogen gas or argon gas.

  Thus, the above-described crystal resonator applies a fluctuating voltage from the outside between the vibration electrodes of the crystal resonator element 5 via the input / output terminal provided on the lower surface of the container body 1, thereby causing the crystal resonator element 5 to have a predetermined frequency. It functions as a quartz crystal resonator by vibrating it through thickness. An oscillation signal generated and output by an external oscillation circuit based on the frequency of the crystal resonator is used as a reference signal (clock signal) in an electronic device such as a portable communication device.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, the lid body 8 is attached to the container body 1 using the seal ring 10. Instead, the lid body is connected to the bonding conductor 9 on the upper surface of the container body. The lid 8 may be attached onto the container body 1 by directly joining the 8.

  In the above-described embodiment, the ground wiring conductor 6 is attached to the inner surface of the notch 4 provided in the recess 1a. However, the present invention is not limited to such an embodiment, and the ground wiring conductor 6 is not limited thereto. May be directly attached to the inner wall surface of the recess 1a, or even when the ground wiring conductor 6 is attached to the inner surface of the notch 4, the notch 4 is provided at a location other than the corner of the recess 1a. May be. In this case, the notch 4 is preferably formed in a semi-cylindrical shape, and the inner surface of the notch 4 is thus curved so that the ground wiring conductor 6 faces the formation region of the notch 4. It can be satisfactorily adhered to the inner surface of 1a.

  Further, in the above-described embodiment, the crystal resonator is configured by using the crystal resonator element as the piezoelectric resonator element. However, other piezoelectric resonators such as a surface acoustic wave element are used to form the piezoelectric resonator. The present invention can also be applied to the case of configuring the above.

1 is an exploded perspective view showing an embodiment in which a piezoelectric vibrator of the present invention is applied to a quartz crystal vibrator. FIG. 2 is a cross-sectional view of the crystal resonator of FIG. 1. It is sectional drawing of the conventional piezoelectric vibrator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Container body 1a ... Concave part 2 ... Connection pad 3 ... External terminal 3a ... Ground terminal 4 ... Notch 5 ... Crystal oscillation element (piezoelectric oscillation element)
6 ... Ground wiring conductor 7 ... Conductive adhesive 8 ... Cover 9 ... Conducting conductor 10 ... Seal ring

Claims (5)

A plurality of external terminals including ground terminals are provided on the lower surface of the container body, a recess is provided on the upper surface, a piezoelectric vibration element is accommodated in the recess, and the opening made of the recess is closed on the upper surface of the container body. In the piezoelectric vibrator with the lid attached,
The piezoelectric vibrator, wherein the lid body and the ground terminal are electrically connected via a ground wiring conductor attached to the inner surface of the concave portion of the container body. 2. The piezoelectric vibrator according to claim 1, wherein the ground wiring conductor is attached to an inner surface of a notch formed in a column shape from the opening of the recess to the bottom of the recess. 3. The piezoelectric vibrator according to claim 2, wherein the concave opening of the container body has a rectangular shape, and the notch is provided at a corner of the opening. The container body has a rectangular shape, and the shortest distance D from the corner portion of the container body to the notch close to the corner portion, and between the container body outer surface and the inner wall of the recess disposed on both sides of the corner portion 4. The piezoelectric vibration element according to claim 3, wherein the thicknesses T ₁ and T ₂ of the side walls are set so as to satisfy both of the following relational expressions (1) and (2).
D ≧ T ₁ ... Relational expression (1)
D ≧ T ₂ ... Relational expression (2) The piezoelectric vibrator according to claim 1, wherein the piezoelectric vibration element is a crystal vibration element.

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