JP2005143042A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability corresponding to a requirement of miniaturization by ensuring a bonding strength of a piezoelectric element and eliminating danger of electrical short-circuiting in a piezoelectric device that fixedly supports the piezoelectric element within a package in a cantilever manner. <P>SOLUTION: A crystal oscillator comprises a package 1 composed of a box-shaped base 3 made of ceramics including a cavity 5 and a planar lid 4 in order to air-tightly seal a crystal oscillation piece 2 formed with exciting electrodes 6a, 6b on its upper and lower surfaces, and a proximal end 2a of the crystal oscillation piece includes drawing electrodes 7a, 7b from the exciting electrodes on its upper and lower surfaces. The crystal oscillation piece is electrically connected and fixedly supported in the cantilever manner by adhering the drawing electrode on its lower surface with a connection electrode 8a on the base of the cavity 5 using conductive adhesives 9. The drawing electrode on the upper surface of the crystal oscillation piece is electrically connected with another connection electrode 8b formed on a lower surface of the lid by a conductive seal 11 for closing a through hole 10 on the lid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to piezoelectric devices such as piezoelectric vibrators, piezoelectric oscillators, surface acoustic wave (SAW) devices used in various electronic devices, and piezoelectric vibration gyros used in angular velocity or rotation sensors. The present invention relates to a surface-mount type piezoelectric device that hermetically seals a piezoelectric element made of a piezoelectric material such as quartz having electrodes formed on the surface thereof in a package.

  Conventionally, various package structures have been adopted for piezoelectric devices, and various devices have been devised in order to meet the demands for miniaturization and thinning along with the miniaturization of electronic equipment and the improvement of airtightness and reliability. For example, in a piezoelectric vibrator that vertically mounts a piezoelectric vibrating piece on a circular base or plug called a hermetic terminal and externally seals a cylindrical metal case, the piezoelectric vibrating piece is disposed so as to pass through the center of the base, Also known is a package structure in which lead electrodes from excitation electrodes provided on each surface of a piezoelectric vibrating piece are joined to inner leads (see, for example, Patent Documents 1 and 2).

  Recently, a surface mount type package structure suitable for mounting on a circuit board or the like has been widely used. Generally, a surface-mount type piezoelectric device has a structure in which a piezoelectric vibrating piece is hermetically sealed in a package composed of a thin box-shaped base made of an insulating material and a thin plate-like lid. In this structure, the piezoelectric vibrating reed is provided with a pair of extraction electrodes on one side of the base end, and is electrically connected to each corresponding connecting electrode of the base with a conductive adhesive or the like. At the same time, it is supported by the base in a cantilever manner (see, for example, Patent Documents 3 and 4). There is also known a method of electrically connecting and fixing a piezoelectric element to a base via a bump formed on a base electrode or a wiring pattern instead of a conductive adhesive (for example, Patent Documents 5 and 6). See).

  Further, in order to accommodate the composite electronic component element in which the piezoelectric device and the capacitive device are integrated in the cavity of the container body in response to the miniaturization of the electronic component, a pair of connections are made to both ends of the bottom surface of the composite electronic component element. A ground electrode is arranged in the center of the upper surface of the electrode, and each connection electrode is bonded to an electrode pad provided on the bottom surface of the cavity with a conductive adhesive, and the sealing portion that seals the cavity opening, that is, the inner surface of the lid and the ground There is a structure in which an electrode is joined with a conductive adhesive (see Patent Document 7). Furthermore, in another piezoelectric device, the lid piezoelectric plate and the bottom piezoelectric plate are hermetically joined and integrated so that the piezoelectric plate having electrodes formed on both upper and lower surfaces is sandwiched from above and below, and the upper and lower electrodes of the sandwiched piezoelectric plate are integrated. There is also known a structure in which conductive bumps respectively extended from a lid part and a bottom piezoelectric plate are pressed to be electrically connected (see Patent Document 8).

Japanese Utility Model Publication No. 6-13221 JP 2002-204140 A JP 2003-8380 A JP 2003-69370 A JP 2002-271168 A JP 2002-290199 A JP 2003-258590 A JP-A-6-350376

  However, in the surface mount package described above, if a pair of connection electrodes are arranged on the bottom surface of the cavity of the box-type base corresponding to the pair of lead electrodes provided at the base end portion of the piezoelectric vibrating piece, the package can be reduced in size. The larger the area, the smaller the area of the connection electrode itself and the distance between the electrodes. For this reason, when the piezoelectric vibrating piece is fixed with a conductive adhesive, there is a possibility that inconveniences such as short-circuiting between connecting electrodes or a decrease in bonding strength of the piezoelectric vibrating piece may occur. Also, in the method of joining by forming conductive bumps on the connection electrodes instead of the conductive adhesive, if two bumps are arranged close to the bottom of the narrow cavity, the bonding area of each bump becomes small. There is a problem that it is difficult to bond both bumps stably and uniformly.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and an object of the present invention is to ensure the bonding strength of the piezoelectric element and to electrically connect the piezoelectric element that is fixedly supported in a package in a cantilever manner. It is to realize the improvement of reliability corresponding to the demand for downsizing.

  According to the present invention, in order to achieve the above object, a piezoelectric element having electrodes formed on the surface thereof and a package for hermetically sealing the piezoelectric element are provided. Each surface has an extraction electrode from the electrode, the package has a connection electrode electrically connected to each extraction electrode of the piezoelectric element inside, and the piezoelectric element has one of its base ends at one end. There is provided a piezoelectric device characterized in that an extraction electrode is electrically connected to a corresponding connection electrode of a package and is thereby fixedly supported in a cantilever manner.

  In order to support the piezoelectric element in a cantilever manner, the one extraction electrode provided on the upper surface or the lower surface of the base end portion is connected to the connection electrode of the corresponding package and, for example, a conductive adhesive or a conductive solder using a conventional technique. It can be connected with a conductive bump formed on a connecting electrode or a connecting electrode. However, only one lead electrode is disposed on the bonding surface of the piezoelectric element in any case using any bonding means. There is no risk of an electrical short circuit with the extraction electrode, a larger bonding area can be secured, and sufficient bonding strength can be obtained. Therefore, even if the piezoelectric device is miniaturized, the assembling work is facilitated, productivity and yield are improved, manufacturing cost can be reduced, and high reliability can be obtained.

  In one embodiment, the package is a surface mount type composed of a base and a lid that is airtightly joined to the base, and the piezoelectric element is fixedly supported in a cantilever manner by providing a connection electrode on either the base or the lid. May be.

  When the piezoelectric element is fixedly supported on the base side, the other connection electrode of the package is provided on the inner surface of the lid, and this is slightly separated from the extraction electrode at a position facing the other extraction electrode of the piezoelectric element. In addition, the lid is provided with a through hole that opens in the region of the other connection electrode, and the other connection electrode and the other extraction electrode can be electrically connected with a molten metal that closes the through hole. it can. As a result, the inside of the package can be sealed and maintained in a desired vacuum or gas atmosphere simultaneously with the connection between the other extraction electrode and the connection electrode, and corrosion of the piezoelectric element or electrode can be prevented to prevent Performance can be maintained and reliability can be improved.

  When the other connection electrode is provided on the base or lid provided with the one connection electrode of the package, it can be electrically connected to the other extraction electrode of the piezoelectric element by wire bonding. The other connection electrode can be arranged at an appropriate position that does not cause an electrical short circuit with the one connection electrode, and the degree of freedom of electrode arrangement is increased by design and reliability is ensured.

  In still another embodiment, the base has a cavity for accommodating the piezoelectric element therein, the one connection electrode is provided on the bottom surface of the cavity, and the one extraction electrode is connected to the piezoelectric element to connect the piezoelectric element. The base end of the piezoelectric element is fixedly supported in a cantilever manner on the base, and the other connection electrode is provided on the side surface of the cavity, and the other end of the piezoelectric element is provided on the side surface of the cavity. The extraction electrode can be electrically connected. As a result, the piezoelectric element can be easily and accurately positioned relative to the base, and the gap between the cavity side surface and the base end edge of the piezoelectric element can be eliminated, thereby reducing the package size accordingly. Therefore, further downsizing can be achieved.

  Further, the base can be provided with a step adjacent to the side surface of the cavity, and the piezoelectric element can be fixedly supported on the base in a cantilever manner by placing the base edge of the piezoelectric element on the top surface of the step and contacting the side surface of the cavity. This step makes it possible to mount the piezoelectric element accurately at a constant height.

  In another embodiment, the base has a cavity for accommodating the piezoelectric element therein, the one connection electrode is provided on the bottom surface of the cavity, a step is formed in the cavity, and the piezoelectric element is connected to the base end thereof. In a state where the edge of the portion is placed on the upper surface of the step, the base is fixedly supported on the base, and the other connection electrode is provided on the upper surface of the step so as to be electrically connected to the other extraction electrode of the piezoelectric element. it can. As a result, similarly, the piezoelectric element can always be accurately mounted at a certain height.

  In the present invention, the piezoelectric element may be a thickness-shear mode piezoelectric vibrating piece, a tuning-fork type piezoelectric vibrating piece, a SAW element, or a piezoelectric vibrating gyro element formed of a piezoelectric material such as quartz. The present invention can be applied to various piezoelectric devices such as vibrators, piezoelectric oscillators, piezoelectric filters, SAW devices, and piezoelectric vibration gyros.

  In one embodiment, the package has a transparent window provided at a position facing the electrode of the piezoelectric element. Thus, for example, when the piezoelectric element is a tuning fork type piezoelectric vibrating piece, the frequency adjustment is performed by irradiating the excitation electrode with a laser beam from the outside through a transparent window after mounting the piezoelectric element on a package. Can do. In particular, the package is a surface-mount type composed of a base and a lid that is airtightly joined to the base. When the package has a sealing hole provided in the base or the lid, the lid is joined to the base on which the piezoelectric vibrating piece is mounted. Conveniently, the frequency can be adjusted and then the package can be sealed to the desired atmosphere.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
1A to 1C schematically show a first embodiment of a crystal resonator to which the present invention is applied. An AT-cut crystal resonator element 2 in a thickness-shear vibration mode is hermetically sealed in a package 1. It is sealed. The package 1 is composed of a base 3 and a lid 4 bonded thereon, and the base 3 is formed by laminating a plurality of ceramic thin plates to form a generally rectangular box shape that defines a cavity 5 that accommodates the crystal vibrating piece 2 therein. The lid 4 is formed of a flat plate made of an insulating material such as ceramics or glass. The quartz crystal vibrating piece 2 is formed of a rectangular quartz thin plate, and excitation electrodes 6a and 6b are formed on the upper and lower surfaces thereof, and extraction electrodes 7a and 7b from each excitation electrode are provided at one end, that is, the base end 2a. Is formed.

  On the bottom surface of the cavity 5, a connection electrode 8 a is formed at a position corresponding to the extraction electrode 7 a on the lower surface of the crystal vibrating piece 2. The quartz crystal vibrating piece 2 is cantilevered and horizontally fixed and electrically connected by a conductive adhesive 9 with the extraction electrode 7a aligned with the connection electrode 8a at the base end 2a. In another embodiment, the lead electrode 7a and the connection electrode 8a are electrically connected using a conductive brazing material or a conductive bump having a low melting point which has been conventionally used instead of the conductive adhesive. However, the base end portion 2a of the crystal vibrating piece 2 can be fixedly supported.

  The lid 4 is arranged so that the lower surface thereof has a slight gap between the upper surface of the quartz crystal vibrating piece 2 mounted on the base 3. As shown in FIG. 2, a connection electrode 8 b is formed on the lower surface of the lid 4 at a position corresponding to the extraction electrode 7 b on the upper surface of the crystal vibrating piece 2. Further, the lid 4 is formed with a through hole 10 opened in the region of the connection electrode 8 b so as to face the extraction electrode 7 b on the upper surface of the crystal vibrating piece 2.

  The through hole 10 is hermetically closed with a suitable conductive sealing material 11 that electrically connects the extraction electrode 7b and the connection electrode 8b. After the lid 4 is joined to the base 3, the sealing material 11 is arranged in a through-hole 10 with a metal ball made of a low melting point conductive brazing material such as Au—Sn, for example, in a desired vacuum environment or gas atmosphere. The through hole 10 is filled by irradiating with a laser beam or the like to melt. As a result, the sealing material 11 closes the through hole 10 to seal and maintain the inside of the package 1 in a desired atmosphere, and is welded to the peripheral edge of the lower opening and the extraction electrode 7b and connected to the extraction electrode 7b. The electrode 8b can be electrically connected. In another embodiment, a conductive adhesive can be used for the sealing material 11 instead of the low melting point conductive brazing material.

  In consideration of the fact that the sealing material 11 flows uniformly around the through hole 10, it is preferable to arrange the through hole 10 so as to be positioned substantially at the center of the extraction electrode 7 b. Further, the gap between the extraction electrode 7b and the connection electrode 8b is determined to an appropriate size in consideration of the fluidity (wetting property, permeability, etc.) of the sealing material 11.

  On the lower surface of the lid 4, an electrode film 12 connected to the connection electrode 8 b is formed in a peripheral portion joined to the upper end surface of the base 3. An electrode film 13 is formed on the upper end surface of the base 3 over the entire circumference, and is connected to the electrode film 14 that continues from the side surface of the cavity 5 to the bottom surface on the distal end side of the crystal vibrating piece 2. Each of the electrode films 12 to 14 can be formed by, for example, a known metallization process. Therefore, the lid 4 and the base 3 are joined by a method that can ensure electrical conductivity between the electrode film 12 and the electrode film 13, for example, a known method such as metal-to-metal joining or seam welding. Therefore, the electrode films 12 and 13 are preferably formed relatively thick. Further, the connection electrode 8b is formed to be thick as well, so that a larger clearance can be provided between the lower surface of the lid 4 and the upper surface of the crystal vibrating piece 2.

  In this way, a wiring circuit extending from the connection electrode 8b to the electrode film 14 via the electrode films 12 and 13 is formed. Further, external electrodes 15a and 15b are provided on the bottom surface of the base 3 in the vicinity of both ends in the longitudinal direction. Each external electrode 15a, 15b is electrically connected to the corresponding connection electrode 8a and electrode film 14 via via holes 16a, 16b penetrating the base 3, respectively. In another embodiment, instead of forming the electrode film 14 on the inner surface of the cavity 5, an electrode film can be formed on the outer surface of the base 3 to connect the electrode film 13 and the external electrode 15b.

  In the present embodiment, only one extraction electrode 7a is disposed on the lower surface of the base end portion 2a of the crystal vibrating piece 2 and can be fixed to the bottom surface of the cavity 5 over substantially the entire surface of the base end portion 2a. Even if the device is downsized, sufficient bonding strength can be secured with a larger bonding area, the assembling work can be facilitated, productivity and yield can be improved, and manufacturing cost can be reduced. Furthermore, there is no possibility of causing an electrical short circuit with the extraction electrode 7b on the upper surface of the base end portion 2a, and high reliability is obtained. Further, since the inside of the package 1 is sealed and maintained in a desired vacuum or gas atmosphere, the crystal resonator element 2 and each electrode film are prevented from being deteriorated and corroded, and the performance and reliability of the crystal resonator are maintained. Can be planned.

  3A and 3B show a modification of the crystal resonator of the first embodiment shown in FIG. In this modification, a transparent window 17 made of glass is provided on the lid 4. The window 17 is provided at a position facing the excitation electrode 6 b on the upper surface of the crystal vibrating piece 2. By irradiating the excitation electrode 6b with a laser beam from the outside of the package 1 through the window 17, the crystal vibrating piece 2 is mounted on the base 3 and the lid 4 is joined, and then the frequency can be adjusted. This is advantageous particularly in the case of an AT-cut quartz resonator in terms of high frequency and high accuracy, or when the tuning-fork type quartz resonator is not an AT-cut quartz resonator. After performing the frequency adjustment in this way, the package 1 is sealed in a desired atmosphere by closing the through hole 10 of the lid 4 with the sealing material 11 as described above. Therefore, according to the present modification, in addition to miniaturization and high reliability of the piezoelectric vibrator, it is possible to cope with high frequency and high performance.

  FIGS. 4A and 4B show another modification of the crystal resonator of the first embodiment shown in FIG. In this modification, a step 18 is provided on the lower surface of the lid 4, the peripheral portion joined to the vicinity of the connection electrode 8 b and the upper end surface of the base 3 is thickened, and a recess 19 is formed in a portion corresponding to the tip side of the crystal vibrating piece 2. Provided. Accordingly, the gap between the connection electrode 8b and the extraction electrode 7b is reduced, and the electrical connection by these sealing materials 11 is facilitated and ensured, and the lower surface of the lid 4 on the tip side of the crystal vibrating piece 2 is secured. The clearance is increased to reduce the possibility that the tip of the quartz crystal vibrating piece 2 will swing and collide with the lower surface of the lid 4 in response to the fall of the quartz crystal vibrator or an external impact.

  Moreover, in another modification of the first embodiment shown in FIG. 1, the through hole 10 of the lid 4 can be omitted. In this case, the extraction electrode 7b and the connection electrode 8b can be electrically connected as follows. After the crystal vibrating piece 2 is mounted on the base 3 with the conductive adhesive 9, an appropriate amount of the conductive adhesive is applied in advance on the lead electrode 7 b on the upper surface thereof, and precured by heating. This conductive adhesive is applied so as to have a height larger than the gap between the extraction electrode 7b and the connection electrode 8b after the precuring. Next, when the lid 4 is placed on the base 3 and these are joined by metal-to-metal joining or seam welding, the conductive adhesive is post-cured by the heat to connect between the extraction electrode 7b and the connection electrode 8b. To do. When the conductive adhesive is selected to have a relatively high elastic modulus so that it does not move away from the lower surface of the lid 4 when the lid 4 is placed on the base 3 and pressed, the connection electrode 8b can be used during post-curing. Can be adhered well.

  5A to 5C schematically show a second embodiment of a crystal resonator to which the present invention is applied. In the second embodiment, one connection electrode 8a is provided on the bottom surface of the cavity 5, and the lead electrode 7a on the bottom surface of the crystal vibrating piece 2 is adhered to the conductive electrode 9 to electrically connect them. This is the same as the first embodiment in that the piece 2 is cantilevered on the base, but the connection electrode 8b corresponding to the extraction electrode 7b on the top surface of the crystal vibrating piece 2 is not overlapped with the crystal vibrating piece 2 on the bottom surface of the cavity 5. It differs from the first embodiment in that it is arranged and connected to the extraction electrode 7b and the bonding wire 20. In this embodiment, a notch is provided at the corner of the cavity 5 adjacent to the crystal vibrating piece base end 2a, and the connection electrode 8b is provided at the bottom thereof. Further, on the bottom surface of the cavity 5, the electrode film 21 is wired to the vicinity of the tip of the quartz crystal vibrating piece 2 along the side wall in the longitudinal direction, and is electrically connected to the external electrode 15 b through the via hole 22 penetrating the base 3 at the end. It is connected.

  By adopting connection by wire bonding in this way, the degree of freedom in designing the base 3 is increased when the connection electrode 8b is arranged. In the modification of the second embodiment shown in FIG. 6, the connection electrode 8 b is formed on the bottom surface thereof by providing a similar notch portion on the side wall in the longitudinal direction of the cavity 5. As described above, the piezoelectric device and / or the package to which the present invention is applied can be disposed at an appropriate position on the bottom surface of the cavity 5 as required. Needless to say, if there is sufficient space on the bottom surface of the cavity 5 so as not to overlap the crystal vibrating piece 2, it is not necessary to provide a notch portion on the cavity side wall as shown in FIG. 5 or FIG. 6. Furthermore, since the wire bonding is performed before the lid 4 is bonded, the extraction electrode 7b and the connection electrode 8b can be more reliably connected, and the reliability is ensured.

  Usually, the lead electrode 7b on the upper surface of the crystal vibrating piece 2 is connected by ball bonding as a first bond, and the connection electrode 8b on the bottom surface of the cavity 5 is connected by wedge bonding as a second bond. However, when the connection electrode 8b on the bottom surface of the cavity 5 is connected by ball bonding as the first bond, and the lead electrode 7b on the top surface of the crystal vibrating piece 2 is connected by wedge bonding as the second bond, the height of the bonding wire 20 is increased in the narrow cavity 5. This is advantageous in reducing the height of the package 1.

  Further, in the second embodiment, the base 3 and the lid are provided so that the upper end surface of the base 3 and the lower surface of the lid 4 are provided with the electrode films 12 and 13 as in the first embodiment and have electrical conductivity therebetween. There is no need to join 4. Therefore, the lid 4 can be formed of various materials such as metal materials conventionally used in piezoelectric devices, in addition to insulating materials such as ceramics or glass, and the base 3 and the lid 4 are made of metal. In addition to inter-bonding and seam welding, bonding can be performed by various appropriate methods such as low-melting glass employed in piezoelectric devices.

  FIGS. 7A and 7B schematically show a third embodiment of a crystal resonator to which the present invention is applied. In the third embodiment, one connection electrode 8a is provided on the bottom surface of the cavity 5, and the extraction electrode 7a on the bottom surface of the crystal vibrating piece 2 is adhered to the conductive electrode 9 to electrically connect them. This is the same as the first embodiment in that the piece 2 is cantilevered by the base 3, but the other connection electrode 8b is formed on the side surface of the cavity 5 adjacent to the base end portion 2a of the crystal vibrating piece 2, and the side surface of the cavity is formed. The base electrode 2a end edge of the quartz crystal vibrating piece 2 is brought into contact with the conductive adhesive 23 between the cavity side surface and the quartz crystal vibrating piece base end 2a, so that the extraction electrode 7b and the connection electrode 8b Are different from the first and second embodiments in that they are electrically connected to each other. In another embodiment, instead of the conductive adhesive 23, preferably a low melting point conductive brazing material can be used.

  As a result, the crystal vibrating piece 2 can be easily and accurately positioned and mounted with respect to the base 3, and the gap between the cavity side surface and the crystal vibrating piece base end 2a can be eliminated. Therefore, the size in the longitudinal direction of the package is reduced accordingly, and the size can be further reduced. Furthermore, the assembly work of the crystal unit becomes easy, the productivity and yield are improved, and the manufacturing cost can be reduced.

  The connection electrode 8b extends along the side surface of the cavity and is connected to the electrode film 13 formed on the upper end surface of the base 3 as in the first embodiment. Similarly, the electrode film 13 is connected to the electrode film 14 continuing from the side surface to the bottom surface of the cavity 5 on the distal end side of the crystal vibrating piece 2 and is connected to the external electrode 15b through the via hole 16b.

  Since the lid 4 has no electrode film as in the first embodiment on its lower surface, it is made of various materials such as insulating materials such as ceramics and glass or metal materials used conventionally as in the second embodiment. can do. And the base 3 and the lid | cover 4 can be joined by various appropriate methods, such as low melting glass, metal-to-metal joining, and seam welding.

  8A and 8B show a modification of the crystal resonator of the third embodiment shown in FIG. In this modification, a step 24 is provided on the side surface of the cavity adjacent to the crystal vibrating piece base end 2 a of the base 3, and the other connection electrode 8 b is formed so as to continue from the side surface of the cavity to the top surface of the step 24. The crystal vibrating piece 2 is cantilevered and fixedly supported on the base 3 with the edge of the base end 2a placed on the upper surface of the step 24, and is electrically conductive between the upper surface of the step 24 and the upper surface of the crystal vibrating piece base end 2a. The adhesive electrode 23 is attached to electrically connect the extraction electrode 7b and the connection electrode 8b. With the step 24, the mount height of the crystal vibrating piece 2 can be always set to be constant and accurate.

  FIGS. 9A and 9B show another modification of the crystal resonator of the third embodiment shown in FIG. In this modification, as in the modification of FIG. 8, the step 24 is provided on the side surface of the cavity adjacent to the crystal vibrating piece base end 2 a, but it is shorter than the case of FIG. 8. The quartz crystal vibrating piece 2 is fixedly supported by the base 3 in a cantilever manner with the edge of the base end portion 2a placed on the upper surface of the step 24 and in contact with the side surface of the cavity. As in the embodiment of FIG. 7, the extraction electrode 7b and the connection electrode 8b are electrically connected by attaching a conductive adhesive 23 between the side surface of the cavity and the upper surface of the crystal vibrating piece base end 2a. . As a result, the quartz crystal vibrating piece 2 can be easily and accurately positioned with respect to the base 3 and can always be accurately mounted at a constant height.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and changes are made to the above-described embodiments within the technical scope thereof. can do. For example, in each of the above-described embodiments, a case where a crystal resonator element is mounted on a base in a surface-mount type package including a base and a lid that is airtightly bonded to the base has been described. Can be mounted in a cantilevered manner.

  The lid can be formed of a metal material having an expansion coefficient similar to ceramics according to the material of the base, such as Kovar (trade name), NSD (42 alloy), NSI (42 alloy), etc. NiFe alloys are preferred. In this case, in the first or third embodiment, the surface is preferably ground-treated with a silicon oxide-based or silicon nitride-based insulating film before the electrode film is formed on the lower surface of the lid.

  Furthermore, the present invention can also be applied to vibrating pieces made of various piezoelectric materials other than quartz. In addition to the thickness-shear mode piezoelectric vibrating piece of the above embodiment, a tuning fork type piezoelectric vibrating piece, a SAW element, or a piezoelectric vibrating gyroscope can be used. The present invention can be applied to various piezoelectric devices such as piezoelectric vibrators, piezoelectric oscillators, piezoelectric filters, SAW devices, and piezoelectric vibration gyros equipped with piezoelectric elements such as elements.

(A) is a plan view showing a first embodiment of an AT-cut quartz crystal resonator according to the present invention with the lid of the package omitted, (B) is a longitudinal sectional view thereof, and (C) is a bottom view thereof. The bottom view of the lid | cover shown in FIG. 1A is a bottom view of a lid according to a modification of the crystal unit shown in FIG. 1, and FIG. 2B is a longitudinal sectional view of the modification. 1A is a bottom view of a lid according to another modification of the crystal unit shown in FIG. 1, and FIG. 2B is a longitudinal sectional view of the modification. (A) is a plan view showing a second embodiment of an AT-cut quartz crystal resonator according to the present invention, with the lid of the package omitted, (B) is a longitudinal sectional view taken along line BB, (C) FIG. These are the longitudinal cross-sectional views in the CC line. The top view which abbreviate | omits the cover of a package and shows the modification of 2nd Example shown in FIG. (A) is a plan view showing a third embodiment of an AT-cut quartz crystal resonator according to the present invention with the package lid omitted, and (B) is a longitudinal sectional view thereof. (A) is a plan view showing a modification of the third embodiment shown in FIG. 7 with the lid of the package omitted, and (B) is a longitudinal sectional view thereof. (A) is a plan view showing another modification of the third embodiment shown in FIG. 7 with the package lid omitted, and (B) is a longitudinal sectional view thereof.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Package, 2 ... Quartz crystal vibrating piece, 2a ... Base end part, 3 ... Base, 4 ... Cover, 5 ... Cavity, 6a, 6b ... Excitation electrode, 7a, 7b ... Extraction electrode, 8a, 8b ... Connection electrode, 9 , 23 ... conductive adhesive, 10 ... through hole, 11 ... sealing material, 12-14, 21 ... electrode film, 15a, 15b ... external electrode, 16a, 16b, 22 ... via hole, 17 ... window, 18, 24 ... steps, 19 ... dents, 20 ... bonding wires.

Claims (16)

A piezoelectric element having an electrode formed on its surface; and a package for hermetically sealing the piezoelectric element,
The piezoelectric element has an extraction electrode from the electrode on each of the upper and lower surfaces of the base end,
The package has a connection electrode electrically connected to each of the extraction electrodes of the piezoelectric element in the package,
The piezoelectric device is characterized in that, at the base end portion, one of the extraction electrodes is electrically connected to the corresponding connection electrode of the package, and is thereby fixedly supported in a cantilever manner. The piezoelectric element is fixedly supported by the package in a cantilever manner by bonding the one extraction electrode to the corresponding connection electrode with a conductive adhesive at the base end portion. 1. The piezoelectric device according to 1. The piezoelectric element is fixedly supported in a cantilever manner on the package by joining the one extraction electrode to the corresponding connection electrode with a conductive brazing material at the base end portion. 1. The piezoelectric device according to 1. The piezoelectric element is fixedly supported by the package in a cantilever manner by connecting the one extraction electrode to the corresponding connection electrode via a conductive bump at the base end portion. Item 2. The piezoelectric device according to Item 1. The package includes a base and a lid that is airtightly joined to the base, and one of the connection electrodes is provided on the base, and the piezoelectric element is fixedly supported by the base in a cantilever manner. The piezoelectric device according to claim 1. The package includes a base and a lid that is airtightly joined to the base, and one of the connection electrodes is provided on the lid, and the piezoelectric element is fixedly supported by the lid in a cantilever manner. The piezoelectric device according to claim 1. The other connection electrode is provided on the inner surface of the lid and at a position facing the other extraction electrode of the piezoelectric element, slightly spaced from the extraction electrode, and the lid is in the region of the other connection electrode. 6. The piezoelectric device according to claim 5, wherein the other connection electrode and the other extraction electrode are electrically connected by a molten metal that has a through-hole that is open in the opening and closes the through-hole. The other connection electrode is provided on the base or lid provided with the one connection electrode, and is electrically connected to the other extraction electrode of the piezoelectric element by wire bonding. The piezoelectric device according to 5 or 6. The base has a cavity that accommodates the piezoelectric element therein, the one connection electrode is provided on a bottom surface of the cavity, and the piezoelectric element has a side surface of the cavity adjacent to an edge of the base end portion. The other connection electrode is provided on the side surface of the cavity and is electrically connected to the other extraction electrode of the piezoelectric element. The piezoelectric device according to claim 5. A step adjacent to the side surface of the cavity is provided, and the piezoelectric element is fixedly supported in a cantilever manner on the base by placing an edge of the base end portion on the upper surface of the step and contacting the side surface of the cavity. The piezoelectric device according to claim 9. The base has a cavity for accommodating the piezoelectric element therein, the one connection electrode is provided on a bottom surface of the cavity, and the other connection electrode is provided on an upper surface of a step formed in the cavity, A piezoelectric element is fixedly supported in a cantilever manner on the base with the edge of the base end portion placed on the upper surface of the step, and the other connection electrode is electrically connected to the other extraction electrode of the piezoelectric element. The piezoelectric device according to claim 5, wherein the piezoelectric device is provided. The piezoelectric device according to any one of claims 1 to 11, wherein the package has a transparent window provided to face the electrode of the piezoelectric element. The piezoelectric device according to claim 1, wherein the piezoelectric element is a piezoelectric vibrating piece in a thickness-shear mode. The piezoelectric device according to claim 1, wherein the piezoelectric element is a tuning fork type piezoelectric vibrating piece. The piezoelectric device according to claim 1, wherein the piezoelectric element is a surface acoustic wave (SAW) element. The piezoelectric device according to claim 1, wherein the piezoelectric element is a piezoelectric vibration gyro element.

Images