JP2010226418A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device which has the support structure of an oscillating piece adaptive to downsizing of the piezoelectric device, and can secure high reliability. <P>SOLUTION: The piezoelectric device 100 includes a package base 10 having a recessed portion 16 formed on an inside bottom surface 18, a support member 30 bonded to the package base 10 with an adhesive 17 provided in the recessed portion 16, a base 42 supported by the support member 30, and the oscillating piece 40 having an arm portion 44 extending from the base 42. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piezoelectric device.

  Conventionally, in response to the demand for downsizing and thinning of electronic devices, the electronic circuit has also been densified, and the electronic components mounted on the circuit board have been made into small chips so as to be suitable for thin and high-density mounting. Many have appeared. In recent years, with the spread of portable communication devices and the like, there is an increasing demand for further miniaturization, weight reduction, and cost reduction of electronic components. The piezoelectric vibrator is also required to be downsized due to the same situation.

  Here, Patent Document 1 discloses a structure in which a piezoelectric vibrating piece is bonded onto an electrode portion of a package using a conductive adhesive.

  However, in the structure disclosed in Patent Document 1, when the size of the piezoelectric vibrator is reduced due to the above-described circumstances, the distance between the portion fixed by the conductive adhesive of the piezoelectric vibrating piece and the vibrating arm is increased. There is a concern that the conductive adhesive may adhere to the vibrating arm, and the reliability may decrease.

JP 2008-72705 A

  One of the objects of the present invention is to provide a piezoelectric device that has a support structure for a resonator element that can be adapted to miniaturization of a piezoelectric device and can ensure high reliability.

  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 aspects or application examples.

[Application Example 1]
A package base with a recess formed on the inner bottom surface;
A support member joined to the package base by an adhesive provided in the recess;
A vibration piece having a base portion supported by the support member and an arm portion extending from the base portion;
Including a piezoelectric device.

  According to such a piezoelectric device, since the adhesive is provided in the concave portion, it is possible to prevent the adhesive from adhering to the arm portion of the vibrating piece. Therefore, it is possible to provide a piezoelectric device that has a support structure for the resonator element that can cope with downsizing and can ensure high reliability.

[Application Example 2]
In application example 1,
The vibrating element is a piezoelectric device that is spaced apart from the adhesive.

  According to such a piezoelectric device, it is possible to prevent the adhesive from reaching the arm portion through the base portion of the vibrating piece. Therefore, a more reliable piezoelectric device can be provided.

[Application Example 3]
In application example 1 or 2,
An excitation electrode formed on the arm;
Mounting terminals formed on the outer bottom surface of the package base,
Including
The adhesive is conductive,
The piezoelectric device, wherein the excitation electrode and the mounting terminal are electrically connected via the adhesive.

  According to such a piezoelectric device, an external driving voltage can be transmitted from the mounting terminal to the excitation electrode via the adhesive.

  In the description according to the present invention, the term “electrically connected” is used, for example, as another specific member (hereinafter “electrically connected” to “specific member (hereinafter referred to as“ A member ”)”. B member "))" and the like. In the description according to the present invention, in the case of this example, the case where the A member and the B member are in direct contact and electrically connected, and the A member and the B member are the other members. The term “electrically connected” is used as a case where the case where the terminals are electrically connected to each other is included.

[Application Example 4]
In any of Application Examples 1 to 3,
The material of the said supporting member is a piezoelectric device which is the same as the material of the said vibration piece.

  According to such a piezoelectric device, since the support member and the vibrating piece can be integrally formed, the support member can be formed by a simple process.

[Application Example 5]
In any of Application Examples 1 to 3,
The piezoelectric device, wherein the support member is a stud bump.

  According to such a piezoelectric device, since the support member can have conductivity, it is not particularly necessary to provide an extraction electrode on the side surface of the support member, and the number of steps can be reduced.

1 is a cross-sectional view schematically showing a piezoelectric device according to an embodiment. The top view which shows typically the piezoelectric device which concerns on this embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric device which concerns on this embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric device which concerns on this embodiment. Sectional drawing which shows typically the piezoelectric device which concerns on the 1st modification of this embodiment. The top view which shows typically the piezoelectric device which concerns on the 1st modification of this embodiment. Sectional drawing which shows typically the piezoelectric device which concerns on the 2nd modification of this embodiment.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

1. Piezoelectric Device First, a piezoelectric device 100 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing the piezoelectric device 100. FIG. 2 is a plan view schematically showing the piezoelectric device 100. 1 is a cross-sectional view taken along the line II of FIG. In FIG. 2, the lid 20 is not shown for convenience.

  As shown in FIGS. 1 and 2, the piezoelectric device 100 includes a package base 10, a support member 30, and a vibrating piece 40. Further, the piezoelectric device 100 can include the lid 20, the excitation electrode 50, the extraction electrode 52, the mounting terminal 54, and the connection wiring 56.

  The package base 10 has a container shape that can accommodate the vibrating piece 40. In the example illustrated in FIG. 2, the planar shape of the package base 10 is a rectangle, but is not particularly limited. Examples of the material of the package base 10 include ceramics and glass. The package base 10 is formed, for example, by laminating a first substrate 12 and a second substrate 14 formed on the first substrate 12. The second substrate 14 can have an opening, and the resonator element 40 can be accommodated in the opening. A recess 16 is formed on the inner bottom surface 18 of the package base 10 (the top surface of the first substrate 12). In the example illustrated in FIG. 2, the planar shape of the recess 16 is a quadrangle, but may be a circle, for example, and is not particularly limited. In the example shown in FIG. 2, two recesses 16 are provided, but the number is not particularly limited. An adhesive 17 can be provided in the recess 16 as will be described later.

  As shown in FIG. 1, the lid 20 is formed on the package base 10 and seals the opening of the package base 10. The lid 20 has a flat plate shape that seals the opening of the package base 10. Examples of the material of the lid 20 include metals such as 42 alloy (an alloy containing 42% nickel in iron) and kovar (alloy of iron, nickel, and cobalt), ceramics, glass, and the like. The cavity 1 formed by the package base 10 and the lid 20 becomes a space for the vibration piece 40 to operate. The cavity 1 can be sealed and installed in a reduced pressure space or an inert gas atmosphere.

  The support member 30 is joined to the package base 10. The support member 30 and the package base 10 are joined by an adhesive 17 provided in the recess 16. The adhesive 17 is, for example, a conductive adhesive in which a resin responsible for fixing and a metal (conductive filler) responsible for conductivity are mixed. In the example shown in FIG. 1, the adhesive 17 is provided so as not to overflow from the recess 16. That is, the upper surface of the adhesive 17 is located below the inner bottom surface 18 (on the outer bottom surface 19 side). As shown in FIG. 2, the support member 30 is provided inside the outer periphery of the recess 16 in plan view. As shown in FIG. 1, the support member 30 has, for example, a bar shape, and extends in the vertical direction (the thickness direction of the vibrator 40, the Z direction). The length (size in the Z direction) of the support member 30 is, for example, 20 μm to 100 μm. The upper end surface of the support member 30 (the surface connected to the lower surface of the vibrating piece 40) is located above the inner bottom surface 18 of the package base 10. The material of the support member 30 can be the same as the material of the vibrating piece 40, and is, for example, a piezoelectric material such as crystal, lithium tantalate, or lithium niobate. In this case, the support member 30 can be formed integrally with the vibrating piece 40.

  The vibrating piece 40 is accommodated in the cavity 1. More specifically, the resonator element 40 is supported by the support member 30 above the inner bottom surface 18. The vibrating piece 40 can be separated from the adhesive 17. Examples of the material of the resonator element 40 include piezoelectric materials such as quartz, lithium tantalate, and lithium niobate. The mode of the vibrating piece 40 is not particularly limited, and examples thereof include a tuning fork vibrating piece and an AT vibrating piece. In the illustrated example, a tuning fork vibrating piece is used as the vibrating piece 40. The vibrating piece 40 includes a base portion 42 and an arm portion 44. The base 42 is connected to the support member 30. The base 42 and the support member 30 may be integrally formed as described above, or may be joined by direct joining. As shown in FIG. 2, the arm portion 44 extends in parallel from the base portion 42 in a bifurcated manner in a direction (X direction) perpendicular to the thickness direction of the vibrator 40. As shown in FIG. 1, the arm portion 44 is separated from the inner bottom surface 18 and can flexurally vibrate in the XY plane.

  The excitation electrode 50 is formed on the arm portion 44. The excitation electrode 50 is an electrode for vibrating the arm portion 44. In the example shown in FIG. 1, the excitation electrode 50 is formed on the upper surface and the lower surface of the arm portion 44. Although not shown, the excitation electrode 50 may be formed on the side surface of the arm portion 44. The excitation electrode 50 can be electrically connected to the conductive adhesive 17 by the extraction electrode 52 formed on the base portion 42 and the support member 30. In the illustrated example, both the excitation electrode 50 formed on the upper surface of the arm portion 44 and the excitation electrode 50 formed on the lower surface are electrically connected to the conductive adhesive 17. Only the conductive adhesive 17 may be electrically connected. As the excitation electrode 50 and the extraction electrode 52, for example, those laminated in the order of chromium and gold from the vibrating piece 40 side can be used.

  The mounting terminal 54 is formed on the outer bottom surface 19 (the lower surface of the first substrate 12) of the package base 10. The mounting terminal 54 can be electrically connected to the conductive adhesive 17 by a connection wiring 56 that penetrates the first substrate 12. That is, the excitation electrode 50 and the mounting terminal 54 are electrically connected via the conductive adhesive 17. Thus, when the piezoelectric device 100 is mounted on a mounting substrate (not shown) or the like, an external driving voltage is applied from the mounting terminal 54 via the connection wiring 56, the conductive adhesive 17, and the extraction electrode 52. , Can be transmitted to the excitation electrode 50. As the mounting terminal 54, for example, a material in which tungsten, molybdenum, nickel, and gold are stacked in this order from the first substrate 12 side can be used. Examples of the material of the connection wiring 56 include gold, copper, and aluminum.

  The piezoelectric device 100 has the following features, for example.

  According to the piezoelectric device 100, the vibrating piece 40 is bonded to the package base 10 via the support member 30, but the support member 30 can be bonded to the package base 10 with the adhesive 17. Since the adhesive 17 is provided in the recess 16 of the package base 10, the adhesive 17 can be prevented from adhering to the arm portion 44 of the vibrating piece 40. That is, for example, even when a large amount of the adhesive 17 is used in consideration of the bonding strength, the adhesive 17 is prevented from overflowing from the recess 16 and adhering to the arm portion 44 by adjusting the depth and size of the recess 16. can do. Therefore, the piezoelectric device 100 has a support structure for the resonator element 40 that can be reduced in size, and can ensure high reliability.

  According to the piezoelectric device 100, the vibrating piece 40 can be separated from the adhesive 17. Therefore, for example, the adhesive 17 can be prevented from reaching the arm portion 44 through the base portion 42 of the vibrating piece 40. Therefore, the piezoelectric device 100 can ensure higher reliability.

  According to the piezoelectric device 100, the adhesive 17 can be conductive. Therefore, an external driving voltage can be transmitted from the mounting terminal 54 to the excitation electrode 50 via the adhesive 17.

  According to the piezoelectric device 100, the material of the support member 30 can be the same as the material of the vibrating piece 40. Therefore, since the support member 30 and the vibrating piece 40 can be formed integrally, the support member 30 can be formed by a simple process.

2. Next, a method of manufacturing the piezoelectric device 100 will be described with reference to the drawings. 3 and 4 are cross-sectional views schematically showing the manufacturing process of the piezoelectric device 100.

  As shown in FIG. 3, a package 10 having a recess 16 formed on the inner bottom surface 18 is prepared. The recess 16 can be formed by, for example, a photolithography technique and an etching technique. The mounting terminal 54 and the connection wiring 56 provided in the package base 10 can be formed by, for example, a sputtering method, a vapor deposition method, a plating method, or the like.

  As shown in FIG. 4, a vibrating piece 40 to which the support member 30 is connected is prepared. The support member 30 and the vibrating piece 40 can be integrally formed, for example, by preparing one piezoelectric substrate (not shown) and etching the piezoelectric substrate. The support member 30 and the vibrating piece 40 are formed separately, and may be joined by direct joining, for example. The excitation electrode 50 and the extraction electrode 52 provided in the vibrating piece 40 can be formed by a sputtering method, a vapor deposition method, a plating method, or the like. Note that the order of preparing the package base 10 and the step of preparing the resonator element 40 are not limited.

  As shown in FIG. 1, the resonator element 40 is joined to the package base 10 via the support member 30. The support member 30 is joined to the package base 10 by the adhesive 17 provided in the recess 16.

  Next, the opening of the package base 10 is sealed with the lid 20. Sealing can be performed by, for example, plasma welding, seam welding, ultrasonic bonding, or an adhesive.

  Through the above steps, the piezoelectric device 100 can be manufactured.

  According to the method for manufacturing the piezoelectric device 100, as described above, the piezoelectric device 100 that has the support structure for the resonator element 40 that can be reduced in size and can ensure high reliability can be obtained.

3. Modification (1) Next, a piezoelectric device 200 according to a first modification of the present embodiment will be described with reference to the drawings. FIG. 5 is a cross-sectional view schematically showing the piezoelectric device 200. FIG. 6 is a plan view schematically showing the piezoelectric device 200. 5 is a cross-sectional view taken along line VV in FIG. In FIG. 6, the lid 20 is not shown for convenience. Hereinafter, in the piezoelectric device 200 according to the first modification of the present embodiment, members having the same functions as those of the constituent members of the piezoelectric device 100 according to the present embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. To do.

  In the piezoelectric device 200, as shown in FIGS. 5 and 6, the base 42 can have a support arm 243, and the support arm 243 can be connected to the support member 30. In the example shown in FIG. 6, the support arm 243 extends in the same direction as the direction in which the arm portion 44 extends. As shown in FIG. 6, two support arms 243 can be provided, and a part of the two arm portions 44 is located between the two support arms 243.

  According to the piezoelectric device 200, even when the distance between the support member 30 and the arm portion 44 is smaller in plan view than the piezoelectric device 100, the adhesive 17 causes the arm portion 44 to be formed by the recess 16. Can be reliably prevented from adhering to the surface.

  (2) Next, a piezoelectric device 300 according to a second modification of the present embodiment will be described with reference to the drawings. FIG. 7 is a cross-sectional view schematically showing the piezoelectric device 300, and corresponds to FIG. Hereinafter, in the piezoelectric device 300 according to the second modified example of the present embodiment, members having the same functions as the constituent members of the piezoelectric device 100 according to the present embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. To do.

  In the piezoelectric device 300, as shown in FIG. 7, stud bumps are used as the support member 330. The support member 330 that is a stud bump is made of, for example, a material whose main component is gold. Specifically, the support member 330 can be formed by making a ball with a gold wire and cutting the tip. The support member 330 is joined to the extraction electrode 52. The support member 330 and the extraction electrode 52 can be joined by, for example, an ultrasonic combined thermocompression bonding method. That is, the support member 330 is pressed against the surface of the extraction electrode 52 while keeping the extraction electrode 52 at a predetermined temperature, and then bonded by solid phase diffusion using gold contained in the extraction electrode 52 and the support member 330. ing. Thereby, the support member 330 and the extraction electrode 52 can be electrically connected.

  According to the piezoelectric device 300, since the support member 330 can have conductivity, it is not particularly necessary to provide an extraction electrode on the side surface of the support member 330, and man-hours can be reduced.

  In addition, embodiment mentioned above and a modification are examples, Comprising: It is not necessarily limited to these. For example, it is possible to appropriately combine each embodiment and each modification.

  Although the embodiments of the present invention have been described in detail as described above, those skilled in the art will readily understand that many modifications are possible without substantially departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention.

1 cavity, 10 package base, 12 first substrate, 14 second substrate, 16 recess, 17 adhesive, 18 inner bottom surface, 19 outer bottom surface, 20 lid, 30 support member, 40 vibration piece, 42 base portion, 44 arm portion , 50 excitation electrode, 52 extraction electrode, 54 mounting terminal, 56 connection wiring, 100 piezoelectric device, 200 piezoelectric device, 243 support arm, 300 piezoelectric device, 330 support member

Claims (5)

A package base with a recess formed on the inner bottom surface;
A support member joined to the package base by an adhesive provided in the recess;
A vibration piece having a base portion supported by the support member and an arm portion extending from the base portion;
Including a piezoelectric device. In claim 1,
The vibrating element is a piezoelectric device that is spaced apart from the adhesive. In claim 1 or 2,
An excitation electrode formed on the arm;
Mounting terminals formed on the outer bottom surface of the package base,
Including
The adhesive is conductive,
The piezoelectric device, wherein the excitation electrode and the mounting terminal are electrically connected via the adhesive. In any of claims 1 to 3,
The material of the said supporting member is a piezoelectric device which is the same as the material of the said vibration piece. In any of claims 1 to 3,
The piezoelectric device, wherein the support member is a stud bump.

Images