JP2010226195A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a piezoelectric device obtained by wire-bonding a substantially rectangular piezoelectric vibrating chip, in plan view. <P>SOLUTION: A piezoelectric vibrator 10 is constituted of a piezoelectric vibration chip 20, having a piezoelectric substrate on which a thin part 22 and a thick part 24 are formed; and a mounting substrate 50, on which the piezoelectric vibration chip 20 is mounted and a connection terminal 52 is formed, wherein an excitation electrode 26 is formed on the thin part 22. A connection electrode 28, electrically connected to the excitation electrode 26 is formed on the thick part 24; a deletion part 32, which is at least one of a notch part formed by partially notching a peripheral edge and a through-hole is formed on the piezoelectric substrate; and a portion of the connection terminal 52, which is exposed from the deletion part 32 in plan view, is connected to the connection electrode 28 by a wire 58. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention particularly relates to a piezoelectric device in which a connection electrode of a piezoelectric vibrating piece and a connection terminal of a mounting substrate are electrically connected by wire bonding.

  Piezoelectric vibrators and piezoelectric devices having piezoelectric vibrators and electronic components in the same package are widely used in electronic equipment such as small information equipment. In recent years, miniaturization and thinning are rapidly progressing in the electronic equipment field, and further miniaturization and thinning are required for piezoelectric devices used in the electronic equipment.

  Conventionally, Patent Document 1 can be cited as an example of a piezoelectric device that has been miniaturized. Patent Document 1 discloses a piezoelectric vibrator in which a thin vibrating portion and a thick annular surrounding portion supporting the periphery of the vibrating portion are integrally formed, and the cross-sectional structure thereof is concave or reverse concave.

  FIG. 8 is a diagram showing a schematic configuration of this piezoelectric vibrator. As shown in FIG. 1A, the piezoelectric vibrator 1 includes an ultra-thin wall portion 5 in which a quartz substrate 2 having a substantially rectangular shape in a plan view is etched to form a main recessed portion 3 and a sub-recessed portion 4 on the inner bottom surface thereof, A thick annular surrounding portion 6 that supports the periphery is integrally formed. Then, the entire surface electrode 7 is formed on the entire surface on the recessed portion side, and the excitation electrode 8, the lead electrode 9, and the connection electrode 9a are simultaneously formed on the main surface on the flat side by vacuum evaporation or the like. The piezoelectric vibrator 1 has a concave or reverse concave cross-sectional structure as shown in FIG.

  According to such a piezoelectric vibrator, the electrode film pressure can be easily controlled, electrical connection with an external terminal can be achieved by wire bonding, and an increase in CI value can be prevented.

JP 2002-368573 A

However, in the conventional piezoelectric vibrator having the above-described structure, when the package is downsized, the annular surrounding portion of the substrate is rectangular, and therefore, wire bonding is performed outside the thick annular surrounding portion. For this reason, as shown in FIG. 8 (3), it is an essential condition to secure a clearance (space) for providing the connection terminal 9d of the mounting substrate 9c. Therefore, there is a problem that it is not possible to sufficiently meet the demands for reducing the size and thickness of the vibrator.
Accordingly, an object of the present invention is to reduce the size of a piezoelectric device in which a piezoelectric vibrating piece having a substantially rectangular shape in plan view is wire-bonded in order to solve the above-described problems of the prior art.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
Application Example 1 A piezoelectric vibration piece having a piezoelectric substrate on which a thin portion and a thick portion are formed, and a mounting substrate on which the piezoelectric vibration piece is mounted and a connection terminal is formed, and the thin portion is excited An electrode is formed, a connection electrode electrically connected to the excitation electrode is formed in the thick part, and at least one of a notch part and a through hole in which a part of a peripheral edge is not formed in the piezoelectric substrate The piezoelectric device is characterized in that a deletion portion is formed, and a portion of the connection terminal exposed from the deletion portion in plan view is connected to the connection electrode by a wire.

  As a result, when the connection electrode of the piezoelectric vibrating piece and the connection terminal on the mounting substrate are wire-bonded, the connection terminal on the mounting substrate is positioned within the region of the piezoelectric vibrating piece. Accordingly, when the piezoelectric vibrating piece is viewed in plan, it is not necessary to newly provide a connection terminal space outside the substantial mounting space of the piezoelectric vibrating piece on the mounting substrate, and the piezoelectric device can be miniaturized. .

Application Example 2 In the piezoelectric device according to Application Example 1, the mounting substrate includes a convex portion disposed adjacent to the piezoelectric substrate at a position overlapping the deletion portion of the piezoelectric substrate in plan view. A piezoelectric device characterized by that.
Thereby, when mounting the piezoelectric vibrating piece on the mounting substrate, the positioning of the piezoelectric substrate can be easily performed.

  Application Example 3 In the piezoelectric device according to Application Example 1 or 2, the deletion portion is formed in each of the thick portions formed at positions sandwiching the thin portion. .

  As a result, the resonator element can be mounted on the mounting substrate without using the conductive adhesive. Therefore, there is no possibility that the organic gas generated when the conductive adhesive is adhered adheres to the piezoelectric vibrating piece and the resonance frequency changes, and a piezoelectric device with high frequency accuracy can be obtained.

  Application Example 4 In the piezoelectric device according to Application Example 1, the deletion portion is formed in each of the thick portions formed at positions sandwiching the thin portion, and the piezoelectric substrate sandwiches the thin portion. Each of the thick-walled portions formed at a position is formed with a positioning deletion portion that is at least one of a cut-out portion and a through-hole cut out at a part of the periphery. A piezoelectric device comprising: a convex portion disposed adjacent to the piezoelectric substrate at a position overlapping the positioning deletion portion of the piezoelectric substrate.

  As a result, the connection terminal and the convex portion are not buffered at the deleted portion of the piezoelectric vibrating piece. Therefore, the connection terminal and the connection electrode can be easily electrically connected by wire bonding, and the piezoelectric vibrating piece can be fixed on the mounting substrate.

It is a figure which shows the structure outline of 1st Embodiment of the piezoelectric vibrator which is an example of the piezoelectric device of this invention. It is explanatory drawing of the modification of a piezoelectric vibrating piece. It is explanatory drawing of the modification of the deletion part of a piezoelectric vibrating piece. It is a figure which shows the structure outline of 2nd Embodiment of the piezoelectric vibrator which is an example of the piezoelectric device of this invention. It is explanatory drawing which shows the modification 1 of the piezoelectric vibrator of 2nd Embodiment. It is a perspective view of the enlarged convex part. It is explanatory drawing which shows the modification 2 of the piezoelectric vibrator of 2nd Embodiment. It is explanatory drawing of the conventional piezoelectric vibrator.

An embodiment of a piezoelectric vibrator, which is an example of a piezoelectric device of the present invention, will be described in detail below with reference to the accompanying drawings.
FIG. 1 is a diagram showing a schematic configuration of the piezoelectric vibrator of the first embodiment. FIG. 1A is a perspective view of the piezoelectric vibrator, FIG. 2B is a plan view (excluding a lid), and FIG. 3C is a sectional view taken along line AA in FIG. As shown in the figure, the piezoelectric vibrator 10 has a piezoelectric vibrating piece 20, a surrounding portion 40, a mounting substrate 50, and a lid body 60 as the main basic configuration.

The mounting substrate 50 is a substantially rectangular substrate that is slightly larger than a rectangular piezoelectric vibrating piece 20 described later. The mounting substrate 50 has a connection terminal 52 formed on the mounting surface and a mounting terminal (not shown) electrically connected to the connection terminal 52 on the back surface. 1 has a connection terminal 52 and a mount electrode 54 formed thereon.
The surrounding portion 40 is formed in a frame shape along the rectangular outer periphery of the mounting substrate 50, and can join with the mounting substrate 50 to form a cavity that accommodates the piezoelectric vibrating reed 20.

The lid 60 is configured to hermetically seal the opening of the cavity after the piezoelectric vibrating reed 20 is mounted in the cavity including the surrounding portion 40 and the mounting substrate 50.
The piezoelectric vibrating piece 20 is a rectangular piezoelectric substrate having a thin-walled portion 22 and a thick-walled portion 24 formed integrally on the side thereof.

  The thin portion 22 becomes a vibration region of the piezoelectric vibrating piece 20, and an excitation electrode 26 is formed at the center. The excitation electrode 26 is formed to face the front and back surfaces of the thin portion 22. The thin portion 22 is set to a predetermined thickness to obtain a high frequency, and is set to a predetermined size around the excitation electrode 26 to prevent vibration leakage.

  The thick portion 24 serves as a support portion when the piezoelectric vibrating piece 20 is mounted on the mounting substrate 50. A connection electrode 28 that is electrically connected to the connection terminal 52 of the mounting substrate 50 is formed in the thick portion 24. The connection electrode 28 is electrically connected to the excitation electrode 26 via the lead electrode 30. The thick portion 24 is set to a predetermined thickness for wire bonding. As shown in FIG. 1, the excitation electrode 26, the lead electrode 30, and the connection electrode 28 can be integrally formed on the front and back surfaces of the piezoelectric vibrating piece 20 by vacuum deposition or sputtering deposition. Further, the thick part 24 is formed with a deletion part 32 in which a part of the piezoelectric substrate having a substantially rectangular shape in plan view is deleted. The deletion part 32 can be formed by, for example, a notch obtained by cutting out a part of the periphery of a rectangular piezoelectric substrate, or a through hole. As shown in FIG. 1 (2), the deletion unit 32 has a connection terminal 52 formed on the mounting substrate 50 when the piezoelectric vibrating reed 20 is mounted on the mounting substrate 50 in a plan view. The overlapping position can be cut out.

  In such a manufacturing method of the piezoelectric vibrating piece 20, when the deletion portion 32 is notched, the deletion portion 32 is integrally formed in advance with the outer shape of the vibration piece. Then, a thin portion 22 and a thick portion 24 are formed by etching. Next, the excitation electrode 26, the lead electrode 30, and the connection electrode 28 are integrally formed on the front and back surfaces of the piezoelectric vibrating piece 20 by vacuum deposition or the like.

  When the piezoelectric vibrating piece 20 is mounted on the mounting substrate 50, a conductive adhesive or wire bonding is used. The piezoelectric vibrator 10 of the first embodiment uses a conductive adhesive and a wire. A cavity for accommodating the piezoelectric vibrating piece 20 is formed by joining the surrounding portion 40 and the mounting substrate 50 in advance, and the connection electrode 28 formed on the back surface of the piezoelectric vibrating piece 20 and the mount electrode 54 on the mounting substrate 50 are conductively bonded. Electrical connection is made using the agent 56, and the piezoelectric vibrating reed 20 is cantilevered horizontally. Next, the connection electrode 28 on the surface of the piezoelectric vibrating piece 20 and the connection terminal 52 arranged at a position overlapping the deleting unit 32 in a plan view of the piezoelectric vibrating piece 20 are electrically connected by a wire 58. The wire bonding of this embodiment uses a gold (Au) wire as an example. After mounting the piezoelectric vibrating piece 20, the opening of the cavity is hermetically sealed with the lid body 60.

  The piezoelectric vibrating piece 20 has a configuration in which the thin portion 22 and the thick portion 24 are integrally formed, and can have a shape as shown in FIG. 2 in addition to the shape shown in FIG. FIG. 2 is an explanatory diagram of a modification of the piezoelectric vibrating piece. FIGS. 1A to 1C are a plan view of the piezoelectric vibrating piece and a cross-sectional view taken along line AA of the plan view, respectively. Specifically, in the piezoelectric vibrating piece 20 a shown in FIG. 2 (1), a thick frame portion 23 a surrounding the thin portion 22 is formed on a pair of sides of the thin portion 22 intersecting with the thick portion 24. A piezoelectric vibrating piece 20b shown in FIG. 2 (2) has a thick frame portion 23b surrounding the thin portion 22 in a U shape. The piezoelectric vibrating piece 20 c shown in FIG. 2 (3) has thick portions 24 a and 24 b formed on both sides of the thin portion 22, and further has a thin portion 22 on a pair of sides of the thin portion 22 that intersects the thick portion 24. A thick frame portion 23c is formed to surround the frame. By providing such frame parts 23a, 23b, 23c or a plurality of thick parts 24a, 24b, a high frequency can be maintained and the strength of the thin part 22 can be reinforced.

  FIG. 3 is an explanatory diagram showing a modification of the deletion unit of the piezoelectric vibrating piece. FIGS. 1A to 1C are a plan view (excluding a lid) of a piezoelectric vibrator accommodating a piezoelectric vibrating piece and a cross-sectional view taken along line AA of the plan view. The deleted portion 32a of the piezoelectric vibrating piece 20d shown in FIG. 3A is a through hole that vertically penetrates the thick portion 24 of the piezoelectric vibrating piece 20d of the piezoelectric substrate having a substantially rectangular shape in plan view. The deletion portion 32a is formed at a position overlapping the connection terminal 52 of the mounting substrate 50 in plan view of the piezoelectric vibrating piece 20d. The connection electrode 28 on the surface is electrically connected to the connection terminal 52 by wire bonding. The connection electrode 28 on the back surface is electrically connected to the mount electrode 54 using a conductive adhesive 56. The deleted portion 32b of the piezoelectric vibrating piece 20e shown in FIG. 3 (2) is formed by cutting out in a U-shape when viewed from the side of the thick portion 24 of the piezoelectric vibrating piece 20e. The deletion portion 32b is formed at a position overlapping the two connection terminals 52a and 52b formed on the mounting substrate 50 in plan view of the piezoelectric vibrating piece 20e. Two connection electrodes 28a and 28b of the piezoelectric vibrating piece 20e are formed on the surface. The connection electrode 28b on the back surface can be formed on the surface by drawing the lead electrode 30b from the back surface to the surface as shown in the figure. Two deletion portions 32c of the piezoelectric vibrating piece 20f shown in FIG. 3 (3) are formed at the corners of the thick portion 24 in plan view of the piezoelectric vibrating piece 20f. The connection electrodes of the piezoelectric vibrating pieces 20e and 20f shown in FIGS. 3 (2) and 3 (3) are formed on the surface of the vibrating piece and are electrically connected to the connection terminals 52 of the mounting substrate 50 by wire bonding. When the piezoelectric vibrating reeds 20e and 20f are mounted on the mounting substrate 50, the TAB tape 57 can be used. 3 can be applied to the piezoelectric vibrating reeds 20a to 20c having the shape shown in FIG.

  According to the piezoelectric vibrator 10 of the first embodiment having the above-described configuration, the connection terminal 52 on the mounting substrate 50 positioned in the deletion unit 32 in plan view of the piezoelectric vibration piece 20 and the connection electrode on the surface of the piezoelectric vibration piece 20. 28 can be electrically connected by a wire 58 within the region of the piezoelectric substrate having a substantially rectangular shape in plan view of the piezoelectric vibrating piece 20.

  Thus, it is not necessary to newly provide a space for the connection terminal 52 in a region outside the substantial mounting space of the piezoelectric vibrating piece on the mounting substrate 50 in a plan view of the piezoelectric vibrating piece 20. Therefore, it is possible to reduce the size of the piezoelectric vibrator in which the piezoelectric vibrating piece is wire-bonded.

Next, as another example of the piezoelectric device of the present invention, the piezoelectric vibrator of the second embodiment will be described below.
FIG. 4 is a diagram showing a schematic configuration of the piezoelectric vibrator of the second embodiment. FIG. 1A is a perspective view of the piezoelectric vibrator, FIG. 2B is a plan view (excluding a lid), and FIG. 3C is a sectional view taken along line AA in FIG. As shown in the figure, the piezoelectric vibrator 100 of the second embodiment is formed with two thick portions 24a and 24b on both sides of the thin portion 22 that becomes the vibration region of the piezoelectric vibrating piece 20g, like the piezoelectric vibrating piece 20c. ing. Deleted portions 32d and 32e are formed in the thick portions 24a and 24b, respectively. Two connection terminals 52a and 52b of the mounting substrate 50 are formed below the thick portions 24a and 24b of the piezoelectric vibrating piece 20g to be mounted on the diagonal line of the substrate. The deletion portions 32d and 32e are formed at a position sandwiching the thin portion 22, that is, the vibration region, and are formed at a position overlapping the connection terminal 52 of the mounting substrate 50 in a plan view of the piezoelectric vibrating piece 20g. The connection electrode 28b on the back surface of the piezoelectric vibrating piece 20g is formed on the surface of the thick portion 24b by drawing the lead electrode 30b from the back surface to the surface.
Other configurations are the same as those of the piezoelectric vibrator 10 of the first embodiment, and the same reference numerals are given and detailed description thereof is omitted.

  According to the piezoelectric vibrator 100 of the second embodiment as described above, the deletion portions 32d and 32e of the piezoelectric vibrating piece 20g in which the two thick portions 24 are formed are connected to the mounting substrate 50 in plan view of the vibrating piece. It is a position that overlaps the terminal 52 and a position that sandwiches the vibration region. Then, the two connection electrodes 28a and 28b on the surface of the piezoelectric vibrating piece 20g, and the connection terminals 52a and 52b of the mounting substrate 50 located in the deletion portions 32d and 32e in plan view of the piezoelectric vibrating piece 20g Wire bonding is performed in a region of the substantially rectangular piezoelectric substrate in plan view, and one end of the wire 58 is connected. The piezoelectric vibrating piece 20g can be mounted on the mounting substrate 50 by two wire bonding, but the piezoelectric vibrating piece 20g and the mounting substrate 50 may be bonded with a TAB tape to increase the strength.

  Thereby, it is not necessary to newly provide a space for the connection terminal 52 in a region (outside) where the piezoelectric vibrating reed 20 mounted on the mounting substrate 50 does not overlap in plan view. Therefore, it is possible to reduce the size of the piezoelectric vibrator in which the piezoelectric vibrating piece is wire-bonded. In addition, since no conductive adhesive is used, there is no possibility that the organic gas generated during the bonding of the conductive adhesive adheres to the piezoelectric vibrating piece and the resonance frequency changes, and a piezoelectric vibrator with high frequency accuracy is obtained. be able to.

  FIG. 5 is an explanatory view showing Modification 1 of the piezoelectric vibrator of the second embodiment. FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along line AA of the plan view. In the piezoelectric vibrator 101 according to the first modification of the second embodiment, convex portions 70a and 70b are formed on the mounting substrate 50 facing the deletion portions 32d and 32e to which one end of wire bonding is connected as illustrated. . The convex portions 70a and 70b serve as bumps and regulating members, and are formed to project at positions adjacent to the corners of the deletion portions 32d and 32e.

FIG. 6 is an enlarged perspective view of the convex portion. As shown in the figure, the convex portions 70 a and 70 b are bumps formed on the dummy electrode 59, for example.
Other configurations are the same as those of the piezoelectric vibrator 100 of the second embodiment, and the same reference numerals are given and detailed description thereof is omitted.

  With this configuration, when the piezoelectric vibrating piece 20g is mounted on the mounting substrate, the deletion portions 32d and 32e and the convex portions 70a and 70b can be disposed adjacent to each other. Therefore, it is possible to easily position the mounting location of the piezoelectric vibrating piece 20g. In addition, the piezoelectric vibrating piece 20g mounted on the mounting substrate 50 can be fixed.

  FIG. 7 is an explanatory view showing a second modification of the piezoelectric vibrator of the second embodiment. In the piezoelectric vibrator 102 according to the second modification of the second embodiment, the deletion portions 32g and 32h and the positioning deletion portions 32f and 32i are formed on the thick portions 24a and 24b of the piezoelectric vibrating piece 20e as illustrated. . The diagonally deleted portions 32g and 32h are formed at positions overlapping the connection terminals 52a and 52b of the mounting substrate 50 in plan view of the piezoelectric vibrating piece 20e. The positioning deletion portions 32f and 32i are formed at positions that do not overlap the connection terminals 52a and 52b of the mounting board 50 when the piezoelectric vibrating piece 20e is viewed in plan. Further, two convex portions 70 c and 70 d are formed on the mounting substrate 50 adjacent to the corners of the positioning deletion portions 32 f and 32 i formed at positions not overlapping the connection terminal 52. As an example, the protrusions 70c and 70d can be bumps formed on the dummy electrodes as in FIG.

With such a configuration, the protruding portion can be disposed adjacent to the positioning deletion portion in the positioning deletion portion where the connection electrode of the piezoelectric vibrating piece and the connection terminal of the mounting substrate are not wire-bonded, and the protrusion and the wire are mutually connected. It can be formed without buffering.
The convex portion may be applied to the piezoelectric vibrator 10 shown in the first embodiment.

  In the present embodiment, the mounting substrate 50 is described using a base substrate. However, the mounting substrate 50 is not limited to this, and an IC element or the like can also be applied. Accordingly, the piezoelectric vibrating piece 20 can be directly mounted on the IC element.

DESCRIPTION OF SYMBOLS 1 ......... Piezoelectric vibrator, 2 ......... Quartz substrate, 3 ......... Main recessed part, 4 ......... Sub-recessed part, 5 ...... Ultra-thin wall part, 6 ......... Annular surrounding part, 7 ... ...... Full-surface electrode, 8 ......... Excitation electrode, 9 ......... Lead electrode, 10 ......... Piezoelectric vibrator, 20 ......... Piezoelectric vibrating piece, 22 ......... Thin portion, 23 ......... Frame portion, 24 ......... Thick part, 26 ......... Excitation electrode, 28 ......... Connecting electrode, 30 ......... Lead electrode, 32 ......... Delete part, 40 ......... Ground part, 50 ...... Mounting substrate, 52 ......... Connecting terminal, 54 ......... Mount electrode, 56 ......... Conductive adhesive, 57 ......... TAB tape, 58 ......... Wire, 59 ......... Dummy electrode, 60 ......... Cover body, 70 .... Convex part.

Claims (4)

A piezoelectric vibrating piece having a piezoelectric substrate on which a thin portion and a thick portion are formed;
A mounting substrate on which the piezoelectric vibrating piece is mounted and a connection terminal is formed;
With
An excitation electrode is formed on the thin portion,
A connection electrode electrically connected to the excitation electrode is formed on the thick part,
In the piezoelectric substrate, a deletion part that is at least one of a notch part and a through hole in which a part of the periphery is cut out is formed,
A portion of the connection terminal exposed from the deleted portion in plan view is connected to the connection electrode by a wire. The piezoelectric device according to claim 1.
The mounting substrate includes a convex portion disposed adjacent to the piezoelectric substrate at a position overlapping the deleted portion of the piezoelectric substrate in plan view. The piezoelectric device according to claim 1 or 2,
The delete device is formed in each of the thick portions formed at positions sandwiching the thin portion. The piezoelectric device according to claim 1.
The deletion part is formed in each of the thick part formed at a position sandwiching the thin part,
In the piezoelectric substrate, a positioning deletion portion that is at least one of a cutout portion and a through hole formed by cutting out a part of the periphery is formed in each of the thick portions formed at positions sandwiching the thin portion. And
The mounting substrate includes a convex portion disposed adjacent to the piezoelectric substrate at a position overlapping the positioning deletion portion of the piezoelectric substrate in plan view.

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