JP2009016951A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device for preventing generation of stray capacitance between a piezoelectric vibration element and a wiring pattern, preventing conductive adhesive from flowing onto the wiring pattern, and preventing oscillation frequency from changing. <P>SOLUTION: The piezoelectric device is provided with a vessel body provided with a first recess space having a frame part on one main surface of a substrate, a piezoelectric vibration element to be mounted on a piezoelectric vibration element mounting pad provided on the substrate part in the first recess space, a cover body for hermetically sealing the first recess space, and an insulating layer formed in the first recess space except the piezoelectric vibration element mounting pad. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a piezoelectric device used in electronic equipment and the like.

FIG. 6 is a cross-sectional view showing a conventional piezoelectric device. FIG. 7 is a main view of a container body constituting a conventional piezoelectric device.
As shown in FIG. 6, a piezoelectric oscillator 200, which is one of piezoelectric devices, has a piezoelectric vibration element 202 mounted in a first concave space 205 provided on one main surface of a container body 201 made of a ceramic material or the like. Has been. A piezoelectric vibration element mounting pad 206 is provided on the substrate portion in the first recess space 205, and the piezoelectric vibration element mounting pad 206 and the piezoelectric vibration element 202 are joined by a conductive adhesive 209.
Further, a metal lid 204 is placed so as to cover the recessed space 205 of the container body 201 and is fixed to the top of the side wall of the container body 201, whereby the inside of the first recessed space 205 is hermetically sealed. .
An integrated circuit element 203 is mounted in a second recessed space 207 formed on the other main surface of the container body 201. An integrated circuit element mounting pad 208 provided on the substrate portion in the second recess space 207 is provided, and a structure in which the integrated circuit element 203 and the integrated circuit element mounting pad 208 are bonded by a conductive bonding material is provided. It is known (see, for example, Patent Document 1).
Further, as shown in FIG. 7, a wiring pattern 210 connected to the piezoelectric vibration element mounting pad 206 is formed on the bottom surface 205 in the first concave space of the container body 201. A structure in which an integrated circuit element mounting pad 208 is connected via the wiring pattern 210 is known (see, for example, Patent Document 2).

JP 2007-104032 A JP 2006-42096 A

  However, in the conventional piezoelectric oscillator 200, the wiring pattern 210 is formed on the substrate portion in the first recess space, and the piezoelectric vibration element mounting pad 206 and the integrated circuit element mounting pad 208 are connected via the wiring pattern 210. However, when the excitation electrode 204 of the piezoelectric vibration element 202 and the wiring pattern 210 are directly opposed to each other, a stray capacitance is generated between the excitation electrode 204 and the wiring pattern 210. There is a problem that the oscillation frequency of the piezoelectric device fluctuates due to the stray capacitance.

  In addition, since the conductive adhesive 209 applied to the piezoelectric vibration element mounting pad 206 flows out onto the wiring pattern 210 when the piezoelectric vibration element 202 is mounted, the conductive adhesive 209 is applied to the surface of the excitation electrode 204 of the piezoelectric vibration element 202. There has been a problem that the conductive adhesive 209 that has flowed out onto the wiring pattern is close, the stray capacitance is further increased, and the oscillation frequency of the piezoelectric device greatly fluctuates.

  Therefore, the present invention has been made in view of the above problems, and prevents the occurrence of stray capacitance between the piezoelectric vibration element and the wiring pattern and prevents the conductive adhesive from flowing out on the wiring pattern, It is an object of the present invention to provide a piezoelectric device capable of preventing fluctuations in oscillation frequency.

  A piezoelectric device according to the present invention includes a container body provided with a frame portion on one main surface of a substrate portion and provided with a first recessed space, and a piezoelectric vibration element mounted on the substrate portion in the first recessed space. A piezoelectric vibration element mounted on the pad and a lid that hermetically seals the first recess space, and an insulating layer that is formed leaving the piezoelectric vibration element mounting pad in the first recess space. It is characterized by being.

  Further, a frame portion is provided on the other main surface of the substrate portion to provide a second recessed space, and the integrated circuit element is mounted on an integrated circuit element mounting pad provided on the substrate portion in the second recessed space. A circuit element is provided.

  The insulating layer is made of aluminum oxide or quartz glass.

According to the piezoelectric device of the present invention, a container body in which a frame portion is provided on one main surface of the substrate portion and the first recessed space is provided, and piezoelectric vibration provided in the substrate portion in the first recessed space. A piezoelectric vibration element mounted on the element mounting pad; and a lid that hermetically seals the first recess space, and an insulating layer that is formed leaving the piezoelectric vibration element mounting pad in the first recess space. Since the wiring pattern formed on the substrate portion in the first recess space is covered with the insulating layer, the floating generated between the excitation electrode of the piezoelectric vibration element and the wiring pattern is formed. Capacitance generation can be prevented, and fluctuations in the oscillation frequency of the piezoelectric device can be prevented.
In addition, since the conductive adhesive applied to the electro-vibration element mounting pad does not flow out onto the wiring pattern by the insulating layer when the piezoelectric vibration element is mounted, the surface of the excitation electrode of the piezoelectric vibration element In addition, it is possible to prevent the conductive adhesive that has flowed out on the wiring pattern from coming close to each other, further increasing the stray capacitance and preventing the oscillation frequency of the piezoelectric device from fluctuating greatly.

  Further, since the insulating layer is made of aluminum oxide or quartz glass, it can be formed by screen printing means.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. A case where quartz is used for the piezoelectric vibration element will be described.
For the sake of clarity, a part of the structure unnecessary for the description is not shown. Further, the illustrated dimensions are partially exaggerated.

(First embodiment)
FIG. 1 is an exploded perspective view showing a piezoelectric vibrator as a piezoelectric device according to an embodiment of the present invention. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a main view of a container body constituting the piezoelectric device according to the embodiment of the present invention.
Hereinafter, a piezoelectric vibrator will be described as an example of the piezoelectric device.

  The piezoelectric vibrator 100 shown in FIGS. 1 to 3 mainly includes a container body 10, a piezoelectric vibration element 20, and a lid body 30. This piezoelectric vibrator 100 has a structure in which a piezoelectric vibration element 20 is mounted in a first recessed space 11 formed on one main surface of the container body 10. .

As shown in FIGS. 1 and 2, the piezoelectric vibration element 20 is formed by depositing an excitation electrode 21 on a crystal base plate, and an alternating voltage from the outside is applied to the crystal base plate via the excitation electrode 21. When applied, excitation occurs in a predetermined vibration mode and frequency.
The quartz base plate is a substantially flat plate shape that is cut from an artificial crystalline lens at a predetermined cut angle and is subjected to external processing, and has a planar shape of, for example, a quadrangle.
The excitation electrode 21 is deposited and formed on both the front and back main surfaces of the quartz base plate.
Such a piezoelectric vibration element 20 includes a conductive adhesive and an excitation electrode 21 attached to both main surfaces of the piezoelectric vibration element 20 and a piezoelectric vibration element mounting pad 13 formed on the inner bottom surface of the first recess space 11. It is mounted in the first recessed space 11 by being electrically and mechanically connected via 70.

The container body 10 includes a substrate portion 10a and a frame portion 10b provided on both main surfaces of the substrate portion 10a.
For example, it is formed by laminating a plurality of ceramic materials such as alumina ceramics and glass-ceramics.
As shown in FIGS. 1 and 2, a first recessed space 11 is formed by one main surface of the substrate portion 10a and the frame portion 10b.
An annular sealing conductor pattern 16 is formed on the entire circumference of the opening-side top surface of the frame portion 10b that surrounds the first recessed space 11 of the container body 10. A piezoelectric vibration element mounting pad 13 and a wiring pattern 18 are provided on the substrate portion 10 a in the first recess space 11.
External connection electrode terminals 14 are provided at the four corners of the other main surface of the substrate portion 10 a of the container body 10.
The piezoelectric vibration element mounting pad 13 and the external connection electrode terminal 14 are formed inside the wiring pattern 18 having a portion formed in the substrate portion 10a in the first recessed space 11 of the container body 10 and the substrate portion 10a. Are connected by via conductors (not shown).

The sealing conductor pattern 16 is provided by being stopped at the end on the top surface side of the frame portion 10b so as to cover the inner side surface and the outer side surface of the frame portion 10b forming the first recessed space 11. It may be done.
This sealing conductor pattern 16 is used when a lid 30 to be described later is joined to the container body 10 to improve the wettability of the sealing member 31 formed on the lid 30 and facilitate joining. Yes. The airtight reliability and productivity of the first recess space can be improved.

  The piezoelectric vibration element mounting pad 13 connected to the excitation electrode 21 includes a wiring pattern 18 (see FIG. 3) provided on the substrate portion 10a in the first recessed space 11 of the container body 10, and the container body 10. Are electrically connected to the external connection electrode terminal 14 via a wiring conductor (not shown), a via-hole conductor (not shown), and the like.

The insulating layer 19 is made of aluminum oxide or quartz glass. The insulating layer 18 is formed of an alumina coat made of aluminum oxide or the like, or a glass coat made of quartz glass or the like. The insulating layer 19 has a structure in which the central area of the main surface of the piezoelectric vibration element mounting pad 13 is exposed, and the main layer of the substrate portion 10 a in the first recess space 11 including the piezoelectric vibration element mounting pad 13 and the wiring pattern 18. It is provided on the surface. The insulating layer 19 is formed by being fired after being provided by screen printing means using a mask jig for masking the central area of the main surface of the piezoelectric vibration element mounting pad 13.
The insulating layer 19 has a thickness of 10 to 50 μm. Since this is thicker than the thickness dimension of the piezoelectric vibration element mounting pad 13, the conductive adhesive 70 remains on the piezoelectric vibration element mounting pad 13. Therefore, the conductive adhesive 70 flowing out on the wiring pattern 18 does not come close to the surface of the excitation electrode 21 of the piezoelectric vibration element 20, and the stray capacitance is further increased and the oscillation frequency of the piezoelectric device greatly fluctuates. Can be prevented.
For example, the insulating layer 19 can be collectively formed by screen printing means in the second recessed space of each container body on the container body in which a plurality of container bodies 10 are arranged and assembled in a planar shape.

The lid body 30 is disposed and joined on the first recessed space 11 of the container body 10. The lid 30 is provided with a sealing member 31 at a location facing the first recessed space 11.
Further, such a sealing member 31 can relieve unevenness on the surface of the sealing conductor pattern 16 and prevent a decrease in hermeticity.

  Further, the lid 30 disposed on the container body 10 is manufactured by adopting a conventionally known metal processing method and shaping a metal such as 42 alloy into a predetermined shape. A nickel (Ni) layer is formed on the upper surface of the lid body 30, and further, gold tin (Au—Sn) which is a sealing member 31 at least at a location facing the sealing conductor pattern 11 on the upper surface of the nickel (Ni) layer. ) Layer is formed. The thickness of the gold tin (Au—Sn) layer is 10 μm to 40 μm. For example, the component ratio is 80% gold and 20% tin.

  The conductive adhesive 70 contains a conductive filler in a silicone resin, and examples of the conductive powder include aluminum (Al), molybdenum (Mo), tungsten (W), and platinum (Pt). , Palladium (Pd), silver (Ag), titanium (Ti), nickel (Ni), nickel iron (NiFe), or a combination thereof is used.

  In the case where the container body 10 is made of alumina ceramics, the piezoelectric vibration element mounting pad 13 and external connection are provided on the surface of a ceramic green sheet obtained by adding and mixing an appropriate organic solvent to a predetermined ceramic material powder. Conductor paste that becomes electrode terminals 14, integrated circuit element mounting pads 15, sealing conductor patterns 16 and the like, and also becomes via conductors in through holes that have been perforated in advance by punching ceramic green sheets. A conductive paste is applied by well-known screen printing, and a plurality of the pastes are laminated and press-molded, and then fired at a high temperature.

  The sealing conductor pattern 16 includes a first recess space 11 in which a nickel (Ni) layer and a gold (Au) layer are sequentially formed on the surface of a base layer made of tungsten (W), molybdenum (Mo), or the like. Is formed to have a thickness of 10 μm to 25 μm.

(Second Embodiment)
FIG. 3 is a main view of a container body constituting the piezoelectric device according to the embodiment of the present invention. FIG. 4 is an exploded perspective view showing a piezoelectric oscillator as a piezoelectric device according to an embodiment of the present invention. 5 is a cross-sectional view taken along the line BB in FIG.
Hereinafter, a piezoelectric oscillator will be described as an example of the piezoelectric device.

  The piezoelectric oscillator 100 shown in FIGS. 3 to 5 mainly includes a container body 10, a piezoelectric vibration element 20, a lid body 30, and an integrated circuit element 50. In the piezoelectric oscillator 100, a piezoelectric vibration element 20 is mounted in a first recessed space 11 formed on one main surface of the container body 10, and is formed on the other main surface of the container body 10. The integrated circuit element 50 is mounted in the second recessed space 12.

  As shown in FIG. 4, the integrated circuit element 50 is provided with an oscillation circuit or the like for generating an oscillation output from the piezoelectric vibration element 20 on the circuit forming surface, and an output signal generated by the oscillation circuit is externally connected. The signal is output to the outside of the piezoelectric oscillator 100 through a predetermined terminal of the electrode terminals 14 and is used as a reference signal such as a clock signal. The integrated circuit element 50 is mounted on the integrated circuit element mounting pad 15 provided in the second recessed space of the container body 10.

The container body 10 includes a substrate portion 10a and frame portions 10b and 10c provided on both main surfaces of the substrate portion 10a.
For example, it is formed by laminating a plurality of ceramic materials such as alumina ceramics and glass-ceramics.
As shown in FIGS. 4 and 5, the first concave space 11 is formed by one main surface of the substrate portion 10a and the frame portion 10b, and the second main surface and the frame portion 10c of the substrate portion 10a are second. The recessed space 12 is formed.
An annular sealing conductor pattern 16 is formed on the entire circumference of the opening-side top surface of the frame portion 10b surrounding the first recessed space 11 of the container body 10. A piezoelectric vibration element mounting pad 13 is provided on the substrate portion 10 a in the first recess space 11.
A monitor electrode terminal 17 is provided at the center of the substrate portion 10 a in the second recessed space 12 of the container body 10.
An integrated circuit element mounting pad 15 for mechanically bonding the integrated circuit element 50 is provided around the monitor electrode terminal 17.
The external connection electrode terminals 14 are provided at the four corners of the opening-side top surface of the frame portion 10 c that surrounds the second recessed space 12.
The piezoelectric vibration element mounting pad 13 and the integrated circuit element mounting pad 15 include a wiring pattern 18 having a portion formed in the substrate portion 10 a in the first recessed space 12 of the container body 10 and the substrate portion 10 a of the container body 10. They are connected by via conductors (not shown) formed inside.
The monitor electrode terminal 17 is not mechanically connected to the integrated circuit element 50.

The integrated circuit element mounting pad 15 is provided around the monitor electrode terminal 17 provided at the center of the substrate portion 10 a in the second recessed space 12 of the container body 10.
The integrated circuit element mounting pad 15 is electrically and mechanically connected to the connection pad formed on the integrated circuit element 50 via a conductive bonding material 60 (see FIG. 5) such as solder or conductive adhesive. Is done. Further, the integrated circuit element mounting pad 15 is formed on the wiring pattern formed on the substrate portion 10 a in the second recessed space 12 of the container body 10 or on the substrate portion 10 a in the first recessed space 11 of the container body 10. The electronic circuit in the integrated circuit element 50 is connected to the crystal resonator element 20 or the like via the wiring pattern 18 and the wiring conductor (not shown) or via-hole conductor (not shown) formed inside the container body 10. It is electrically connected to the external connection electrode terminal 14.

The monitor electrode terminal 17 is provided in the central portion of the substrate portion 10 a in the second recessed space 12 on the other main surface of the container body 10 and is formed in a shape larger than the integrated circuit element mounting pad 15. ing.
The monitor electrode terminal 17 is connected to the piezoelectric vibration element 20 via a piezoelectric vibration element mounting pad 13 provided on the substrate portion 10 a in the first recessed space 11 of the container body 10. And used to measure electrical characteristics such as a CI (crystal impedance) value and a resonance frequency value of the piezoelectric vibration element 20.

  Further, by forming the insulating layer 19 on the substrate portion 10a of the first recessed space 11 of the container body 10, the warping of the container body 10 is mitigated by the expansion of the insulating layer 19, When the integrated circuit element 50 is mounted on the inner bottom surface of the second recessed space 12 of the container body 10, it is possible to reliably mount the integrated circuit element 50 and ensure the bonding strength.

  Further, if the ground terminal and the oscillation output terminal are arranged close to each other among the four external connection electrode terminals 14, it is possible to effectively prevent noise from interfering with the oscillation signal output from the oscillation output terminal. Can do. Therefore, it is preferable to arrange the ground terminal and the oscillation output terminal close to each other.

(Third embodiment)
The piezoelectric oscillator is mainly composed of a first container body, a second container body, a piezoelectric vibration element, a lid body, and an integrated circuit element. In this piezoelectric oscillator, a piezoelectric vibration element is mounted in a recessed space formed on one main surface of the first container body, and the inside of the recessed space 12 formed on one main surface of the second container body. The integrated circuit element 50 is mounted on the second container body connecting terminal formed on the other main surface of the first container body and a second surface formed on the main surface of the second container body. One container body electrode terminal may be joined.

In addition, this invention is not limited to the said embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.
For example, in the above-described embodiment, the case where crystal is used as the piezoelectric material constituting the piezoelectric vibration element 20 has been described. However, as other piezoelectric materials, lithium niobate, lithium tantalate, or piezoelectric ceramics is used as the piezoelectric material. The piezoelectric vibration element used may be used.

It is a disassembled perspective view which shows a piezoelectric vibrator as a piezoelectric device which concerns on embodiment of this invention. It is AA sectional drawing of FIG. It is a container main body figure which comprises the piezoelectric device which concerns on embodiment of this invention. It is a disassembled perspective view which shows a piezoelectric oscillator as a piezoelectric device which concerns on embodiment of this invention. It is BB sectional drawing of FIG. It is sectional drawing which shows the conventional piezoelectric device. It is a container main surface figure which comprises the conventional piezoelectric device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Container body 10a ... Board | substrate part 10b, 10c ... Frame part 11 ... 1st recessed part space 12 ... 2nd recessed part space 13 ... Piezoelectric vibration element mounting pad 14 ... -External connection electrode terminal 15 ... Integrated circuit element mounting pad 16 ... Sealing conductor pattern 17 ... Monitor electrode terminal 18 ... Wiring pattern 19 ... Insulating layer 20 ... Piezoelectric vibration Element 21 ... Excitation electrode 30 ... Cover 31 ... Sealing member 50 ... Integrated circuit element 60 ... Conductive bonding material 70 ... Conductive adhesive 100 ... Piezoelectric device (Piezoelectric vibrator Piezoelectric oscillator)

Claims (3)

A container body provided with a frame portion on one main surface of the substrate portion and provided with a first recessed space;
A piezoelectric vibration element mounted on a piezoelectric vibration element mounting pad provided on the substrate portion in the first recess space;
A lid for hermetically sealing the first recessed space,
A piezoelectric device comprising an insulating layer formed by leaving a piezoelectric vibration element mounting pad in a first recess space.   An integrated circuit element mounted on an integrated circuit element mounting pad provided in the second recess space by providing a frame portion on the other main surface of the substrate portion to provide a second recess space. The piezoelectric device according to claim 1, comprising:   The piezoelectric device according to claim 1, wherein the insulating layer is made of aluminum oxide or quartz glass.

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