JP2005236892A - Package for housing piezoelectric vibrator and piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-reliability package for housing a piezoelectric vibrator and piezoelectric device in which an area for packaging on an external electric circuit board can be reduced and the piezoelectric vibrator to be housed internally can be stably vibrated. <P>SOLUTION: A package for housing a piezoelectric vibrator comprises: a parallellopiped insulating substrate 3 having a parallellopiped recess 2 for housing a piezoelectric vibrator on its upper surface; an electrode 5 which is formed on the base of the recess 2 and in which the piezoelectric vibrator 1 is electrically connected to its upper surface; a wiring conductor 10 formed from the electrode 5 to a side surface of the insulating substrate 3; and a connecting pad 6 for external connection which is formed on the side surface and electrically connected with the wiring conductor 10. The electrode 5 is formed in an outer peripheral portion of the base of the recess 2 so as to make the outer peripheral side of the base of the recess 2 thicker than its central side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a piezoelectric vibrator housing package and a piezoelectric device for housing a piezoelectric vibrator inside.

  Conventionally, as a piezoelectric vibrator housing package for housing a piezoelectric vibrator, a ceramic package made of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, glass ceramics, or the like has been used. Yes. As shown in FIGS. 4A and 4B, the conventional package has a rectangular parallelepiped concave portion 32 for accommodating the piezoelectric vibrator 31 at the center of the upper surface, and the corner of the bottom surface of the concave portion 32. A rectangular parallelepiped insulating base 33 provided with a step 34 to which the end of the piezoelectric vibrator 31 is attached is provided. An electrode 35 is formed on the upper surface of the stepped portion 34, and a wiring conductor 40 made of a metallized conductor or the like is led out from the electrode 35 to the lower surface of the insulating base 33. 4A is a plan view showing an example of a conventional piezoelectric vibrator housing package and a piezoelectric device, and FIG. 4B is a cross-sectional view taken along the line BB ′ of FIG. 4A. .

  The piezoelectric vibrator 31 is housed in the concave portion 32 of the insulating base 33 so that the main surface thereof faces the bottom surface of the concave portion 32, and the end of the piezoelectric vibrator 31 is placed on the stepped portion 34 in the concave portion 32. The electrode 35 exposed to the electrode 35 is electrically connected through an electrical connection means such as a conductive adhesive 39, and then the lid 37 is joined around the concave portion 32 on the upper surface of the insulating base 33 to thereby provide insulation. A piezoelectric device in which the piezoelectric vibrator 31 is hermetically sealed inside a container including the recess 32 and the lid 37 of the base 33 can be configured. The recess 32 is bonded to the sealing metallization layer 38 formed at a portion surrounding the recess 32 on the upper surface of the insulating base 33 by a seam weld method or the like via a brazing material such as silver brazing. Is hermetically sealed.

The piezoelectric device thus formed is positioned and placed on an external electric circuit board (not shown) so that the lower surface of the insulating base 33 faces the upper surface of the external electric circuit board. The wiring conductor 40 led to the lower surface and the electrode pad of the external electric circuit board are connected to each other through a brazing material such as solder, so that the piezoelectric vibrator 31 and the external electric circuit are connected to the wiring conductor. 40 is electrically connected. The portion of the wiring conductor 40 connected to the electrode pad of the external electric circuit board is formed so as to have a large area such as a quadrangular shape or an elliptical shape in order to make the connection easy and strong. It functions as a connection pad for external connection (electrically connecting a piezoelectric vibrator housing package or a piezoelectric device to an external electric circuit board).
JP 2002-33636 A

  In recent years, there has been a strong demand for such a piezoelectric vibrator housing package and a piezoelectric device to be miniaturized, particularly to reduce a mounting area when mounted on an external electric circuit board.

  However, the conventional package for housing a piezoelectric vibrator has the following problems. That is, since the piezoelectric vibrator 31 is housed so that its main surface faces the bottom surface of the recessed portion 32 of the insulating base 33, if it is attempted to be housed in the recessed portion 32 without disturbing the vibration of the piezoelectric vibrator 31, It is necessary to secure the area of the bottom surface of the recess 32 as much as the main surface of the piezoelectric vibrator 31 having a large area, and accordingly, the area when the insulating base 33 is viewed from the main surface side is large. Become. The insulating base 33 containing the piezoelectric vibrator 31 is mounted such that the main surface (lower surface) having a large area faces the upper surface of the external electric circuit board. As a result, there is a problem that it is very difficult to reduce the mounting area of the piezoelectric vibrator housing package and the piezoelectric device on the external electric circuit board.

  The present invention has been devised in view of such problems, and an object of the present invention is to reduce the mounting area of the external electric circuit board and to stably vibrate the piezoelectric vibrator housed inside. It is an object of the present invention to provide a highly reliable piezoelectric vibrator housing package and a piezoelectric device capable of satisfying the requirements.

  The package for housing a piezoelectric vibrator of the present invention includes a rectangular parallelepiped insulating base having a rectangular parallelepiped recess for housing the piezoelectric vibrator on the upper surface, and a piezoelectric vibrator electrically formed on the bottom surface of the recess. An electrode to be connected; a wiring conductor formed from the electrode to a side surface of the insulating base; and a connection pad for external connection formed on the side surface and electrically connected to the wiring conductor. And the said electrode is formed in the outer peripheral part of the bottom face of the said recessed part so that an outer peripheral part side may become thicker than the center part side of the bottom face of the said recessed part.

  The piezoelectric device of the present invention includes the piezoelectric vibrator housing package of the present invention, a piezoelectric vibrator housed in the concave portion and electrically connected to the electrode, and the concave portion on the upper surface of the insulating base. And a lid attached to cover the recess.

  In the piezoelectric device according to the aspect of the invention, it is preferable that the lid body is provided with a protrusion at a portion facing the electrode on the lower surface, and the piezoelectric vibrator is sandwiched between the protrusion and the electrode. It is attached to the insulating substrate.

  The package for housing a piezoelectric vibrator of the present invention is a wiring conductor formed from an electrode to which a piezoelectric vibrator is connected to a side surface of an insulating base, and an external connection formed on the side surface and electrically connected to the wiring conductor. Since the connection pad for external connection formed on the side surface and the electrode pad of the external electric circuit board can be connected to face each other, a rectangular parallelepiped shape having a small area is provided. The area of the external electric circuit board only needs to be secured by an amount corresponding to one side surface of the insulating base, and the mounting area for the external electric circuit board can be made very small.

  In the piezoelectric vibrator housing package of the present invention, the electrode is formed on the outer peripheral portion of the bottom surface of the concave portion so that the outer peripheral portion side is thicker than the central portion side of the bottom surface of the concave portion. When the end portion is electrically connected to the electrode on the bottom surface of the recess through an electrically connecting means such as a conductive adhesive, the conductive adhesive is accumulated in the gap formed between the piezoelectric vibrator and the electrode. The piezoelectric vibrator can be firmly bonded to the electrode. As a result, a mechanical shock or vibration is applied to the piezoelectric vibrator storage package, and this impact is combined with gravity, and a large stress acts on the joint surface between the electrode and the piezoelectric vibrator in the direction along the joint surface. In addition, it is possible to effectively prevent the piezoelectric vibrator from being detached from the electrode, and to improve the connection reliability of the piezoelectric vibrator.

  In addition, the piezoelectric device of the present invention includes a piezoelectric vibrator housing package having the above configuration, a piezoelectric vibrator housed in the recessed portion and electrically connected to the electrode, and a recessed portion around the recessed portion on the upper surface of the insulating base. Since the lid is attached so as to cover the external electric circuit board, the mounting area in a plan view with respect to the external electric circuit board is small, and the connection reliability of the piezoelectric vibrator can be excellent. .

  In the piezoelectric device according to the present invention, preferably, the lid is provided with a protrusion at a portion facing the electrode on the lower surface, and the piezoelectric vibrator is sandwiched between the protrusion and the electrode and is attached to the insulating substrate. Therefore, the end portion of the piezoelectric vibrator can be sandwiched between the electrode and the protruding portion, and the bonding between the electrode and the piezoelectric vibrator can be made more effective.

  Therefore, the piezoelectric device of the present invention can reduce the mounting area with respect to the external electric circuit board, and the piezoelectric vibrator after mounting does not come off from the electrode, can increase the mechanical strength, and is housed inside. It is possible to make the piezoelectric vibrator having high reliability capable of stably vibrating.

  Next, a piezoelectric vibrator housing package and a piezoelectric device according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a plan view showing an example of an embodiment of a piezoelectric vibrator housing package and a piezoelectric device according to the present invention, FIG. 2 is a side view thereof, and FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG. It is. In the figure, 1 is a piezoelectric vibrator, 3 is an insulating substrate, 5 is an electrode, 6 is a connection pad, and 10 is a wiring conductor. The insulating substrate 3, the electrode 5, the connection pad 6, and the wiring conductor 10 mainly constitute the piezoelectric vibrator housing package of the present invention. The piezoelectric vibrator of the present invention is configured by housing the piezoelectric vibrator 1 in this piezoelectric vibrator housing package and sealing it with the lid 7.

  The insulating substrate 3 is made of a ceramic or a resin such as an aluminum oxide sintered body (alumina ceramic), an aluminum nitride sintered body, a mullite sintered body, or a glass ceramic, and has a side length of about 2 to 20 mm, for example. It has a rectangular parallelepiped shape with a thickness of about 0.5 to 3 mm.

  Further, a rectangular parallelepiped recess 2 for housing the piezoelectric vibrator 1 is formed on the upper surface of the insulating base 3.

  The insulating base 3 and the recess 2 are formed in a rectangular parallelepiped shape in order to efficiently accommodate the square plate-like piezoelectric vibrator 1. Although FIG. 1 shows an example in which the insulating base 3 and the recess 2 are formed in a rectangular shape when viewed from the main surface side of the insulating base 3, the shape, characteristics, etc. of the piezoelectric vibrator 1 to be accommodated are shown. Accordingly, it may be formed in a square shape.

  Such an insulating substrate 3 is manufactured as follows. First, in the case of an aluminum oxide sintered body, an appropriate organic binder, solvent, plasticizer, etc. are added to and mixed with raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide to form a mud. This is formed into a sheet shape by a conventionally known doctor blade method, calendar roll method, or the like to obtain a plurality of ceramic green sheets. Thereafter, the ceramic green sheet is appropriately punched to form a square shape and a frame shape, and the frame shape is positioned in the upper layer so that the square shape is positioned in the lower layer. In this manner, a laminated body having a concave portion 2 formed on the upper surface is formed by stacking up and down, and the laminated body is fired at a high temperature (about 1600 ° C.) to form the insulating substrate 3.

  The electrode 5 formed on the bottom surface of the recess 2 of the insulating base 3 functions as a pad for electrically connecting the piezoelectric vibrator 1 housed in the recess 2.

  The piezoelectric vibrator 1 is, for example, a crystal, a surface acoustic wave element, or the like, and generally has a rectangular plate shape, and a connection electrode (not shown) made of a metal material such as gold at its end. Is deposited.

  By connecting the connection electrode at the end of the piezoelectric vibrator 1 to the electrode 5 on the bottom surface of the recess 2 via a conductive adhesive 9 or the like, the piezoelectric vibrator 1 can be mounted on a package. Done.

  In this case, since the connection electrode of the piezoelectric vibrator 1 is formed at the end, the electrode 5 is provided at the corner of the bottom surface of the concave portion 2 in order to easily store the piezoelectric vibrator 1 in the concave portion 2 without waste. Etc., such as a portion close to the side surface of the recess 2.

  Further, since the piezoelectric vibrator 1 electrically connected to the electrode 5 vibrates and transmits a signal having a predetermined frequency, it is necessary not to prevent this vibration. Therefore, it is necessary to secure a certain space between the main surface of the piezoelectric vibrator 1 and the bottom surface of the concave portion 2, and the stepped portion 4 and the convex portion are disposed on the bottom surface of the concave portion 2 in order to increase the height of the electrode 5. The electrode 5 is preferably formed so as to be exposed on the upper surface of the stepped portion 4 and the convex portion. The stepped portion 4 and the convex portion are made of, for example, an insulating material similar to that of the insulating base 3, and a mud-like mixture similar to that for forming the insulating base 3 is formed in the concave portion 2 of the ceramic green sheet serving as the insulating base 3. It can be formed by applying to the corners of the bottom surface. Further, the step portion 4 and the convex portion may be formed of the same metal material as that of the electrode 5.

  In the piezoelectric vibrator housing package of the present invention, the wiring conductor 10 is formed from the electrode 5 to the side surface of the insulating base 3. In addition, connection pads 6 that are electrically connected to the wiring conductor 10 are formed on the side surfaces of the insulating base 3.

  The connection pad 6 is a pad for external connection, and the connection pad 6 is electrically connected to an electrode pad (not shown) of the external electric circuit board via solder or the like, so that the connection electrode of the piezoelectric vibrator 1 is connected. Are electrically connected to the electrode pad of the external electric circuit board and the external electric circuit connected to the electrode pad via the electrode 5, the wiring conductor 10 and the connection pad 6.

  According to the package for housing a piezoelectric vibrator of the present invention, the connection pads 6 formed on the side surface of the insulating base 3 can be connected so as to face the electrode pads of the external electric circuit board. The area of the external electric circuit board only needs to be secured by an amount corresponding to one side surface of the insulating base 3, and the mounting area on the external electric circuit board can be made extremely small.

  In the piezoelectric vibrator housing package of the present invention, as shown in FIG. 3, the electrode 5 is formed on the outer peripheral portion of the bottom surface of the concave portion 2 so that the outer peripheral portion side is thicker than the central portion side of the bottom surface of the concave portion 2. Has been.

  With this configuration, when the end portion of the piezoelectric vibrator 1 is electrically connected to the stepped portion 4 in the concave portion 2 or the electrode 5 exposed on the convex portion via an electrical connecting means such as a conductive adhesive 9, A reservoir of the conductive adhesive 9 can be formed in the gap formed between the piezoelectric vibrator 1 and the electrode 5, and the piezoelectric vibrator 1 can be firmly bonded to the electrode 5. As a result, a mechanical shock or vibration is applied to the piezoelectric vibrator housing package, and this shock is combined with gravity, and a large stress acts on the joint surface between the electrode 5 and the piezoelectric vibrator 1 in the direction along the joint surface. Even if it does, it can prevent effectively that the piezoelectric vibrator 1 remove | deviates from the electrode 5, and can make the reliability of the connection of the piezoelectric vibrator 1 excellent.

  Therefore, the piezoelectric vibrator housing package of the present invention can make the mounting area with respect to the external electric circuit board very small, and the connection reliability of the piezoelectric vibrator 1 to the external electric circuit is extremely excellent. be able to.

  The electrode 5 needs to be formed so that the outer peripheral portion side is thicker than the central portion side of the bottom surface of the recess 2. For example, the electrode 5 is inclined at the same angle from the central portion side toward the outer peripheral portion side. 3 so that the height is increased by inclining at a certain angle from the end on the central side to the middle of the recess 2 as shown in FIG. A horizontal shape up to the end of the side, that is, a structure having a step or the like can be employed. Preferably, a structure having a step as shown in FIG. 3 is used, so that the piezoelectric vibrator 1 and the electrode 5 can be easily and more accurately aligned, and the electrode 5 and the conductive layer are electrically conductive. As the bonding area horizontally facing the conductive adhesive 9 and the like is increased, the bonding strength between the electrode 5 and the conductive adhesive 9 is further increased.

  In addition, the electrode 5 has a step between the end on the center side and the end on the outer periphery, so that a pool of the conductive adhesive 9 is formed on the outer periphery side with respect to the center side of the recess 2. You may make it raise the height of.

  Here, when connecting the connection pads 6 for external connection formed on the side surfaces of the insulating base 3 and the electrode pads of the external electric circuit board, the notches 11 are formed in the outer peripheral corners of the insulating base 3. In addition, it is preferable that the metallized layer 12 is formed on the inner surface of the notch 11 and the connection pad 6 is formed so that the outer end of the connection pad 6 is in contact with the lower end of the metallized layer 12. . As a result, a solder fillet connecting the connection pad 6 to the electrode pad of the external electric circuit board is formed between the external electric circuit board and the metallized layer 12. Therefore, the piezoelectric vibrator housing package (piezoelectric device) can be more firmly bonded to the external electric circuit board.

  In addition, the connection pads 6 formed on the side surface of the insulating base 3 are preferably formed at both ends of the long side surface when the insulating base 3 is rectangular when viewed from the main surface side. If it is formed at both ends on the long side, it is difficult to fall when mounted on an external electric circuit board, so that the reliability of external connection can be further improved.

  Moreover, it is preferable to form the connection pad 6 in the same arrangement | positioning form on the two long side sides which oppose. In this case, since the wiring conductor 10 is formed so as to be connected to the electrode 5 that connects the piezoelectric vibrator 1 on either of the long sides, the connection pad 6 and the outside can be connected without considering the orientation of the piezoelectric device. It is possible to connect the electrode pads of the electric circuit board, and it is possible to obtain a piezoelectric vibrator housing package that can be more easily connected externally.

  The electrode 5, the connection pad 6, and the wiring conductor 10 are made of a metal material such as tungsten, molybdenum, manganese, copper, or silver. For example, when made of tungsten, an organic solvent, a binder, or the like is added to the tungsten powder. The conductive paste produced by kneading is formed by printing a predetermined pattern on the surface of a green sheet to be the insulating substrate 3.

  Note that the exposed surfaces of the electrode 5, the wiring conductor 10, and the connection pad 6 prevent oxidation corrosion of the electrode 5, the wiring conductor 10, and the connection pad 6, and each of the connection electrodes of the electrode 5 and the piezoelectric vibrator 1. For example, a nickel plating layer having a thickness of about 1 to 10 μm and a gold plating layer having a thickness of about 0.1 to 3 μm are sequentially formed in order to strengthen the connection between the connection pad 6 and the external electric circuit board. It should be attached.

  Then, the piezoelectric vibrator 1 is accommodated in the recess 2 of the insulating base 3, and a connection electrode (not shown) formed at the end of the piezoelectric vibrator 1 is conductively bonded to the electrode 5 formed on the bottom surface of the recess 2. The piezoelectric vibrator 1 is connected to the insulating base 3 by connecting the cover 7 through the electrical connecting means such as the agent 9 and attaching the lid 7 so as to cover the concave 2 on the upper surface of the insulating base 3. And the lid 7 are hermetically sealed to complete the piezoelectric device.

  In this case, the lid body 7 is attached to the upper surface of the insulating substrate 3 by means such as joining via a brazing material. Here, when the lid 7 is joined to the insulating base 3 or when the piezoelectric device is connected to the external electric circuit board, the brazing material joining the lid 7 and the insulating base 3 flows. From the viewpoint of preventing the wiring conductor 10 and the connection pad 6 for external connection from being short-circuited (electrically short-circuited), an insulator is desirable.

  The bonding material used for bonding the lid 7 and the insulating substrate 3 is the same as that when the lid 7 is bonded to the insulating substrate 3 or when the piezoelectric device is connected to the external electric circuit substrate. From the viewpoint of preventing the brazing material joining 3 to flow and short-circuiting the wiring conductor 10 and the connection pad 6 for external connection, an insulating material such as resin or low-melting glass is desirable. With recent downsizing and thinning of electronic devices, the distance between the electrodes 5 formed on the bottom surface of the recess 2 of the insulating substrate 3 and electrically connected to the piezoelectric vibrator 1 on the top surface has become very small. As a result of this reduction in size and thickness, the brazing material can easily flow into the recess 2 when the lid 7 is joined to the frame 8, and a short circuit occurs between the wiring conductor 10 and the connection pad 6 for external connection. However, short-circuiting of the wiring conductor 10 and the connection pad 6 for external connection can be effectively prevented by using the bonding material as an insulator as described above.

  Note that the recess 2 does not need to be a completely rectangular parallelepiped, and the inner corner of the recess 2 is formed in an arc shape, and mechanical damage such as cracks is effectively prevented from occurring in the insulating base 3 at the corner. You may make it do. Further, a part of the upper surface surrounding the recess 2 of the insulating base 3 is projected toward the inside of the recess 2 to the extent that the vibration of the piezoelectric vibrator 1 is not hindered. A larger bonding area may be secured and the bonding between the lid body 7 and the insulating base 3 may be made stronger.

  Further, in the piezoelectric device of the present invention, the lid body 7 is provided with a protrusion 4 ′ at a portion facing the electrode 5 on the lower surface, and the piezoelectric vibrator 1 is sandwiched between the protrusion 4 ′ and the electrode 5. And is preferably attached to the insulating substrate 3.

  For example, the protrusion 4 ′ can bond and fix the piezoelectric vibrator 1 through a conductive adhesive similar to the conductive adhesive 9 that connects the piezoelectric vibrator 1 to the electrode 5. In addition, without fixing with an adhesive or the like, the distance between the protrusion 4 ′ and the electrode 5 is set to be the same as or slightly shorter than the thickness of the piezoelectric vibrator 1, so that the protrusion 4 ′ You may make it fix only with the force pinched | interposed between the electrodes 5, attaching the elastic body which has insulation, such as a silicon | silicone.

  As described above, when the protrusion 4 ′ is provided on the lower surface of the lid 7 facing the electrode 5, and the piezoelectric vibrator 1 is sandwiched between the protrusion 4 ′ and the electrode 5 and attached to the insulating substrate 3. In other words, the end portions of both main surfaces of the piezoelectric vibrator 1 are fixed between the electrode 5 and the protrusion 4 ′ via a conductive adhesive (or an elastic body having insulation properties). Thus, the bonding between the electrode 5 and the piezoelectric vibrator 1 can be made more effective.

  In addition, this invention is not limited to the example of the above-mentioned embodiment, A various deformation | transformation is possible. For example, in the embodiment of the present invention, an example in which three ceramic layers are laminated is shown, but the insulating substrate 3 may be formed by laminating four or more ceramic layers.

  Further, in FIG. 1A, the electrodes 5 are formed at two diagonal corners on the inner surface of the recess 2, but two electrodes 5 are formed on the left and right according to the arrangement of the connection electrodes of the piezoelectric vibrator 1 and the like. May be.

It is a top view which shows an example of embodiment of the package for piezoelectric vibrator accommodation of this invention. FIG. 2 is a side view of the piezoelectric vibrator housing package of FIG. 1. FIG. 2 is a cross-sectional view taken along line A-A ′ of the piezoelectric vibrator housing package of FIG. 1. (A) is a plan view of a conventional piezoelectric vibrator housing package, and (b) is a cross-sectional view taken along line B-B ′ of the piezoelectric vibrator housing package of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator 2 ... Concave part 3 ... Insulation base | substrate 4 '... Protrusion part 5 ... Electrode 6 ... Connection pad 7- .... Lid 9 ... Conductive adhesive 10 ... Wiring conductor

Claims (3)

A rectangular parallelepiped insulating base having a rectangular parallelepiped recess for accommodating the piezoelectric vibrator on the upper surface, an electrode formed on the bottom surface of the concave portion and electrically connected to the piezoelectric vibrator on the upper surface, and the insulation from the electrode A wiring conductor formed on a side surface of the base; and a connection pad for external connection formed on the side surface and electrically connected to the wiring conductor. A package for accommodating a piezoelectric vibrator, wherein the outer peripheral portion side is formed on the outer peripheral portion so that the outer peripheral portion side is thicker than the central portion side of the bottom surface of the concave portion. The piezoelectric vibrator housing package according to claim 1, a piezoelectric vibrator housed in the concave portion and electrically connected to the electrode, and the concave portion covering the concave portion on the upper surface of the insulating base. A piezoelectric device comprising a lid attached in this manner. The lid is provided with a protrusion at a portion of the lower surface facing the electrode, and is attached to the insulating substrate with the piezoelectric vibrator interposed between the protrusion and the electrode. The piezoelectric device according to claim 2.

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