JP2010219876A - Piezoelectric device - Google Patents

Abstract

In a piezoelectric device on which a resonator element and an IC chip are mounted, a piezoelectric device capable of increasing the strength of a package is provided.
A piezoelectric device according to the present invention includes a package base, a lid disposed above the package base and sealing the package base, and a cavity formed by the package base and the lid. 1 and an IC chip 20 housed in the cavity 1 with the active surface 22 facing downward, and an inactive surface opposite to the active surface 22 of the IC chip 20. 24 is joined to the lower surface of the lid 18.
[Selection] Figure 1

Description

  The present invention relates to a piezoelectric device.

  Piezoelectric vibrators typified by quartz vibrators are used in products in a wide range of fields. The piezoelectric vibrator is used as an oscillator for obtaining a reference frequency signal, for example, in a timepiece or an information communication device. Also, in digital cameras and automobiles, for example, it is used as a mechanical sensor for controlling the posture of the device. Thus, the piezoelectric vibrator is used in various fields, and a piezoelectric vibrator having particularly high package strength is required depending on the field.

  For example, in Patent Document 1, a crystal resonator element and an IC chip for driving the crystal resonator element are mounted on a piezoelectric vibrator package.

  However, in the structure disclosed in Patent Document 1, since the crystal resonator element and the IC chip are mounted in parallel, the area of the package increases, and the strength of the package may decrease.

JP 2004-343398 A

  One of the objects of the present invention is to provide a piezoelectric device capable of increasing the strength of a package in a piezoelectric device on which a resonator element and an IC chip are mounted.

  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]
Package base,
A lid disposed above the package base and sealing the package base;
A vibrating piece housed in a cavity formed by the package base and the lid;
An IC chip accommodated in the cavity with the active surface facing downward;
Including
A piezoelectric device, wherein an inactive surface opposite to the active surface of the IC chip is bonded to a lower surface of the lid.

  According to the piezoelectric device of the present invention, the lower surface of the lid is bonded to the non-active surface, so that the strength of the package can be increased.

  In the description of the present invention, the word “upper” is, for example, “forms another specific thing (hereinafter referred to as“ B ”)“ above ”a specific thing (hereinafter referred to as“ A ”)”. Etc. In the description according to the present invention, in the case of this example, the case where B is directly formed on A and the case where B is formed on A via another are included. The word “upward” is used.

[Application Example 2]
In application example 1,
The piezoelectric device, wherein the inactive surface is bonded to the lower surface of the lid by an adhesive.

  According to the piezoelectric device of the present invention, for example, even when an external force is applied to the package, the inactive surface and the lower surface of the lid can be prevented from separating, and the strength of the package can be reliably increased. it can.

[Application Example 3]
In application example 2,
The adhesive is a piezoelectric device containing a metal filler.

  According to the piezoelectric device of the present invention, since the adhesive having high thermal conductivity can be used, for example, heat generated by driving the IC chip is released from the lid to the outside through the adhesive. This can increase heat dissipation.

[Application Example 4]
In application example 3,
A ground terminal formed on the lower surface side of the package base;
The piezoelectric device in which the non-active surface is electrically connected to the ground terminal via the lid.

  According to the piezoelectric device of the present invention, since the inactive surface can be electrically connected to the ground terminal, the ground of the inactive surface can be strengthened, and the electrical characteristics of the IC chip can be improved. Can be stabilized.

  In the description according to the present invention, the phrase “electrically connected” is used as, for example, another specific member (hereinafter “electrically connected” to “specific member (hereinafter referred to as“ C member ”)”. It is used as "D member"). In the description according to the present invention, in the case of this example, the case where the C member and the D member are directly connected and electrically connected, and the C member and the D 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.

1 is a cross-sectional view schematically showing a piezoelectric device according to an 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 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.

  As illustrated in FIG. 1, the piezoelectric device 100 includes a package 10 having a package base 12 and a lid 18, an IC chip 20, and a vibrating piece 30. Further, the piezoelectric device 100 can include a first terminal 80 and a second terminal 82.

  The package base 12 has a container shape that can accommodate the IC chip 20 and the vibrating piece 30. The package base 12 has a substrate 14 and a seal ring 16. The upper surface of the substrate 14 (the surface on which the IC chip 20 and the resonator element 30 are mounted) can be a flat surface. The material of the substrate 14 is, for example, an inorganic material such as ceramic or glass. Wirings 60, 62, 64 can be formed on the upper surface side of the substrate 14. The material of the wirings 60, 62, 64 is, for example, tungsten, molybdenum, nickel, gold, or the like. The seal ring 16 is formed on the upper surface side of the substrate 14. The seal ring 16 has a ring-like planar shape. With the seal ring 16, the package base 12 can have an opening that accommodates the IC chip 20 and the vibrating piece 30 therein. The material of the seal ring 16 is, for example, a metal such as 42 alloy (an alloy containing 42% nickel in iron) or Kovar (an alloy of iron, nickel, and cobalt), ceramics, or the like.

  The lid 18 is formed on the package base 12. More specifically, the lid 18 is bonded to the upper surface of the seal ring 16. The lid 18 has a flat plate shape that seals the opening of the package base 12. The material of the lid 18 is, for example, a metal such as 42 alloy or Kovar, ceramics, or the like. The package base 12 and the lid 18 form a cavity 1 that accommodates the IC chip 20 and the vibrating piece 30. The cavity 1 can be sealed and installed in a reduced pressure space or an inert gas atmosphere.

  The IC chip 20 is accommodated in the cavity 1. The IC chip 20 is flip-chip bonded to the package base 12. That is, the IC chip 20 has electrodes 26 and 28 and is accommodated in the cavity 1 with the active surface 22 on which the electrodes 26 and 28 are formed facing downward (face down). The electrodes 26 and 28 can be electrically connected to the wirings 60 and 62 by bumps 50, respectively. The electrodes 26 and 28 have, for example, a multilayer structure such as aluminum or copper. The bump 50 is made of, for example, gold. The inactive surface 24 opposite to the active surface 22 of the IC chip 20 faces upward. The inactive surface 24 is joined to the lower surface of the lid 18. In the illustrated example, the inactive surface 24 is bonded to the lower surface of the lid 18 by an adhesive 40. As the adhesive 40, for example, a silica-based adhesive, an epoxy resin-based adhesive, or the like can be used. The IC chip 20 can include, for example, a drive circuit for driving and vibrating the vibration piece 30 and a detection circuit for detecting a detection vibration generated in the vibration piece 30 when an angular velocity is applied.

  The vibrating piece 30 is accommodated in the cavity 1. The vibration piece 30 is accommodated in parallel with the IC chip 20, for example. The mode of the vibrating piece 30 is not particularly limited, and examples thereof include an AT vibrating piece, a tuning fork vibrating piece, and a SAW vibrating piece. The material of the resonator element 30 is, for example, a piezoelectric material such as crystal, lithium tantalate, or lithium niobate. The vibrating piece 30 includes electrodes 32 and 34, and a part of the vibrating piece 30 is sandwiched between the electrodes 32 and 34. The electrodes 32 and 34 are electrodes for driving the vibrating piece 30, for example. The material of the electrodes 32 and 34 of the vibrating piece 30 is the same as the material of the electrodes 26 and 28 of the IC chip 20, for example. The electrodes 32 and 34 can be electrically connected to the wirings 62 and 64 by bumps 50, respectively. In the illustrated example, the electrode 32 of the resonator element 30 is electrically connected to the electrode 28 of the IC chip 20 via the wiring 62.

  The first terminal 80 and the second terminal 82 are formed on the lower surface of the package base 12 (the lower surface of the substrate 14). The 1st terminal 80 and the 2nd terminal 82 consist of multilayer structures, such as tungsten, molybdenum, nickel, and gold, for example. The first terminal 80 can be, for example, a ground terminal. The second terminal 82 can be, for example, a power supply terminal. The first terminal 80 can be electrically connected to the wiring 60 by a contact 70 that penetrates the substrate 14. The second terminal 82 can be electrically connected to the wiring 64 by a contact 72 that penetrates the substrate 14. The material of the contacts 70 and 72 is, for example, gold, copper, or aluminum.

  The piezoelectric device 100 according to the present embodiment has, for example, the following characteristics.

  In the piezoelectric device 100, the inactive surface 24 of the IC chip 20 can be bonded to the lower surface of the lid 18. Therefore, for example, deformation of the lid 18 due to external force can be prevented. That is, the package 10 having the lid 18 can have high strength. Thereby, for example, the lid 18 and the vibrating piece 30 can be prevented from coming into contact with each other due to the deformation of the lid 18.

  In the piezoelectric device 100, the inactive surface 24 of the IC chip 20 can be bonded to the lower surface of the lid 18 with an adhesive 40. Therefore, for example, even when an external force is applied to the package 10, it is possible to prevent the non-active surface 24 and the lower surface of the lid 18 from separating. Therefore, the strength of the package 10 can be reliably increased.

2. Next, a method of manufacturing the piezoelectric device 100 will be described with reference to the drawings. FIG. 2 is a cross-sectional view schematically showing the manufacturing process of the piezoelectric device 100.

  As shown in FIG. 2, the package base 12 on which the IC chip 20 and the vibrating piece 30 are mounted is prepared. The IC chip 20 is mounted by flip chip bonding. The vibrating piece 30 is mounted by a known method, for example. Note that wirings 60, 62, 64, contacts 70, 72, and terminals 80, 82 are formed on the substrate 14 of the package base 12 by, for example, a known method.

  Next, the adhesive 40 is applied to the non-active surface 24 of the IC chip 20.

  As shown in FIG. 1, an opening of the package base 12 is sealed with a lid 18 to form a package 10. More specifically, the lid 18 is bonded to the upper surface of the seal ring 16 by plasma welding, seam welding, ultrasonic bonding, adhesive, or the like. At that time, the lower surface of the lid 18 and the non-active surface 24 are bonded by the adhesive 40.

  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 capable of increasing the strength of the package 10 can be obtained.

3. Modified Example Next, a piezoelectric device 200 according to a modified example of the present embodiment will be described with reference to the drawings. FIG. 3 is a cross-sectional view schematically showing the piezoelectric device 200. Hereinafter, in the piezoelectric device 200 according to the 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.

  In the piezoelectric device 200, as shown in FIG. 3, the inactive surface 24 of the IC chip is bonded to the lower surface of the lid 18 with an adhesive 240. The adhesive 240 contains a metal filler. The material of the metal filler is not particularly limited. The adhesive 240 can be electrically conductive by containing a metal filler. Moreover, heat conductivity can be improved.

  In the piezoelectric device 200, the inactive surface 24 is electrically connected to the first terminal 80 through the adhesive 240, the lid 18, the seal ring 16, and the contact 274 that penetrates the substrate 14. That is, in the piezoelectric device 200, the material of the lid 18 is an electrically conductive metal. The material of the seal ring 16 can be an electrically conductive metal. The material of the seal ring 16 can also be ceramics, for example. In that case, the lid 18 and the contact 274 can be electrically connected by a contact (not shown) penetrating the seal ring 16. . The contact 274 is made of the same material as the contacts 70 and 72, for example, and is formed by a known method.

  According to the piezoelectric device 200, as described above, the inactive surface 24 of the IC chip 20 and the first terminal 80 can be electrically connected. Since the first terminal 80 can be a ground terminal, the non-active surface 24 can be electrically connected to the ground terminal. Therefore, in the piezoelectric device 200, the ground of the non-active surface 24 can be strengthened, and the electrical characteristics of the IC chip 20 can be stabilized.

  Moreover, according to the piezoelectric device 200, the adhesive 240 with high thermal conductivity can be used. Therefore, for example, heat generated by driving the IC chip 20 can be released to the outside from the lid 18 via the adhesive 240. That is, the piezoelectric device 200 can improve heat dissipation and have high reliability.

  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, 12 package base, 16 seal ring, 18 lid, 20 IC chip, 22 active surface, 24 inactive surface, 26 electrode, 28 electrode, 30 vibrator element, 32 electrode, 34 electrode, 40 adhesive 50 bump, 60 wiring, 62 wiring, 64 wiring, 70 contact, 72 contact, 80 first terminal, 82 second terminal, 100 piezoelectric device, 200 piezoelectric device, 240 adhesive, 274 contact

Claims (4)

Package base,
A lid disposed above the package base and sealing the package base;
A vibrating piece housed in a cavity formed by the package base and the lid;
An IC chip accommodated in the cavity with the active surface facing downward;
Including
A piezoelectric device, wherein an inactive surface opposite to the active surface of the IC chip is bonded to a lower surface of the lid. In claim 1,
The piezoelectric device, wherein the inactive surface is bonded to the lower surface of the lid by an adhesive. In claim 2,
The adhesive is a piezoelectric device containing a metal filler. In claim 3,
A ground terminal formed on the lower surface side of the package base;
The piezoelectric device in which the non-active surface is electrically connected to the ground terminal via the lid.

Images