JP2004135190A - Surface-mounted piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator of a structure, wherein the piezoelectric vibrator and IC component are accommodated in an airtight space within a container, which can solve the problems that the formation of a stepped part for mounting of the vibrator in an inner recessed wall of the container having the airtight space therein results in a reduced surface area for mounting of the IC component and that a parasitic capacitance of a wiring pattern connected with an exciting electrode of the vibrator results in an unstabilized oscillation output frequency. <P>SOLUTION: The piezoelectric oscillator consists of the container 2, the piezoelectric vibrator 20, and the IC component 30. The container 2 has a body 5 and a metal lid 10 for sealing a recess 9, in the inner surface of annular outer wall 6 of the container body. The IC component 30 has a body 31 provided mutually facing upper surfaces 6a of the outer wall, first component terminals 32 provided on a lower surface of the component body to be connected with connection pads 7 of the container via bumps, and second component terminals 33, provided on a lower surface of the component body, to be electrically and mechanically connected with lead terminals 23 of the vibrator via bumps. The vibrator is located in the recess on the inner surface of the outer wall, by supporting the vibrator from the lower side of the component body. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a surface mount type piezoelectric oscillator having a single seal structure in which a piezoelectric vibrating element and an IC component are accommodated in an airtight space of the same container. The present invention relates to a surface-mount type piezoelectric oscillator capable of outputting a stable frequency while suppressing a change in load capacitance of the piezoelectric device.
[0002]
[Prior art]
With the spread of mobile communication devices such as mobile phones, price reductions and rapid progress in miniaturization, the cost and size of piezoelectric oscillators such as crystal oscillators used in these communication devices have been reduced. Demand for height reduction is increasing.
In order to respond to such a demand, conventionally, an IC component (semiconductor integrated circuit component) as a chip component and a piezoelectric vibrating element are housed in an airtight space of one container, and this airtight space is sealed with a metal lid. A surface mount type piezoelectric oscillator having a single seal structure has been proposed.
As this type of surface mount type piezoelectric oscillator, for example, the one disclosed in Japanese Patent No. 2969526 as shown in FIG. 5 is known. This oscillator has a step 102 for mounting a crystal piece in a recess 101 of a container body 100 made of a laminated ceramic, and has a connection pad 103 on the step 102. A crystal blank 110 is electrically and mechanically connected to the connection pad 103. On the inner bottom surface of the recess 101, a wiring pattern including the internal electrode 104 is formed, and an IC component 115 is mounted. The metal cover 107 is seam-welded via a welding ring 106 provided on the upper surface of the outer wall 105 of the recess 101 to hermetically seal the inside of the recess 101.
However, in the piezoelectric oscillator described in the above publication, it is necessary to provide a step 102 for supporting a quartz piece in the recess 101 of the container body 100. There is a problem that the component mounting area is inevitably narrowed, and the selection range of the mountable IC components 115 is narrowed. That is, for example, in order to manufacture a temperature-compensated crystal oscillator (TCXO) having a vertical and horizontal dimension of 2.5 × 2.0 mm in a planar shape, for a TCXO having a planar shape of 1.0 mm or less, respectively. Although the IC component 115 is required, it is extremely difficult to manufacture such a small-sized IC component at present. When the IC component 115 is mounted on the internal electrode 104 on the inner bottom surface of the recess 101, the IC component is positioned on the inner bottom surface of the recess while the IC component is sucked and held by a suction unit (not shown). Since it is necessary to secure a margin space for mounting work between the IC and the side surface of the IC component, it is necessary to increase the plane area of the recess by that much. For this reason, there is a limit to miniaturization of the piezoelectric oscillator.
In the recess 101, a wiring pattern including a connection pad 103 connected to the excitation electrode on the crystal blank 110 is formed. However, since these wiring patterns have not a small amount of parasitic capacitance, The influence makes it difficult to secure a highly stable oscillation output frequency.
[Patent Document 1] Japanese Patent No. 2969526 [0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above, and in a surface-mounted piezoelectric oscillator having a structure in which an IC component chipped together with a piezoelectric vibrating element is accommodated in an airtight space in a container, a concave portion of the container forming the airtight space The reduction of the IC component mounting area due to the formation of the step for mounting the piezoelectric vibrating element on the inner wall, and the reduction of the oscillation output frequency due to the parasitic capacitance of the wiring pattern connected to the excitation electrode of the piezoelectric vibrating element It is an object of the present invention to provide a surface-mounted piezoelectric oscillator that can eliminate instability.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a surface-mount type piezoelectric oscillator according to the present invention comprises a bottom plate made of an insulating material having a mounting terminal for surface mounting on an outer bottom portion, and an insulating material integrated on the bottom plate. A container comprising: an annular outer wall; a plurality of connection pads for mounting IC components disposed on the upper surface of the annular outer wall; and a seam ring projecting from the upper surface of the annular outer wall to an outer diameter side of each of the connection pads. A container comprising: a main body; a metal lid fixed to a seam ring of the container main body to seal a recess inside the annular outer wall; and an excitation electrode and an excitation electrode on a main surface of the piezoelectric substrate. A piezoelectric vibrating element having lead terminals extending therefrom, an IC component main body having an area that can be placed and mounted between opposing upper surfaces of the annular outer wall, and connected to the connection pads provided on a lower surface of the IC component main body. The first part to be And a second component-side terminal provided on the lower surface of the IC component body and electrically and mechanically connected to each lead terminal of the piezoelectric vibrating element. The piezoelectric vibrating element is supported by a lower surface, so that the piezoelectric vibrating element is arranged in a recess inside the annular outer wall.
In a piezoelectric oscillator in which a piezoelectric vibrator and an IC component are hermetically sealed in a recess of an insulating container such as a ceramic, a step is conventionally provided on the inner wall of the recess, and the piezoelectric vibrator is mounted on the step, After the IC component was connected to the bottom surface in the recess, the opening of the recess was sealed with a metal lid. For this reason, under the demand for the miniaturization of the piezoelectric oscillator, the space on the bottom surface in the recess as the IC component accommodating area is limited while the miniaturization of the IC component is also limited. The structure has been a great hindrance to miniaturization of the piezoelectric oscillator. In addition, since the wiring pattern for connection to the piezoelectric vibrating element arranged in the recess has a considerable amount of parasitic capacitance, it is difficult to secure a highly stable oscillation output frequency due to the influence of the parasitic capacitance. was there.
On the other hand, according to the present invention, the inside of the recess is not used as a space for mounting the IC component, and the IC component is mounted across the upper surface of the outer wall located outside the recess. However, the recess functions only as a space for fitting and arranging the piezoelectric vibration element. Therefore, the flat area of the container can be reduced in size and thickness. In addition, since the piezoelectric vibrating element is electrically and mechanically connected and supported directly on the lower surface of the IC component, there is no wiring pattern for connection with the piezoelectric vibrating element in the recess, and transmission due to the influence of parasitic capacitance is eliminated. Instability of the output frequency can be prevented.
According to a second aspect of the present invention, in the first aspect, each of the second component side terminals on the lower surface of the IC component main body and each of the lead terminals on the piezoelectric vibration element side are connected using a plurality of bumps. It is characterized by.
According to this, since the electrical and mechanical bonding strength of the piezoelectric vibration element to the IC component can be increased, the durability and reliability can be improved.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on an embodiment shown in the accompanying drawings.
In the following embodiments, a surface-mounted crystal oscillator will be described as an example of a surface-mounted piezoelectric oscillator.
1 (a), 1 (b), 1 (c) and 1 (d) are a plan view (with a metal cover removed), an AA 'cross-sectional view, and a container of a surface mount type crystal oscillator according to an embodiment of the present invention. It is a top view of a main part, and a bottom view of IC parts.
The crystal oscillator 1 is of a type in which a crystal resonator element 20 and IC components (semiconductor integrated circuit components) 30 constituting an oscillation circuit and a temperature compensation circuit are housed in an airtight space in a container 2.
That is, the container 2 includes a bottom plate 3 made of an insulating material such as a ceramic having a mounting terminal 4 for surface mounting on an outer bottom portion, an annular outer wall 6 made of an insulating material such as a ceramic integrated on the bottom plate 3, and an annular outer wall 6. A plurality of connection pads 7 for mounting IC components disposed on each upper surface 6a along the long sides facing each other, and seam welding protruding from the upper surface of the annular outer wall to the outer diameter side from each connection pad 7 Body 5 having a seam ring 8 which is a metal frame for use, and a metal lid body which is welded and fixed on the seam ring 8 of the container body 5 to seal a recess 9 inside the annular outer wall 6. And 10. The thickness of the annular outer wall 6 is larger on the long side provided with the connection pad 7 on the upper surface 6a than on the short side, so that the upper surface 6a as a space for mounting the connection pad 7 is provided. It is possible to secure. The connection pad 7 is separated from the seam ring 8 located on the outer diameter side by 200 μm or more, and an oscillation output terminal, a power supply terminal, a ground terminal, and the like arranged on the bottom surface of the container main body via a conductor pattern wired inside the container. Are respectively connected to the mounting terminals 4.
The crystal vibrating element 20 includes two excitation electrodes 22 each formed of a conductive material on both main surfaces of a crystal substrate 21, and lead terminals 23 extending from each excitation electrode 22 to an edge of the crystal substrate 21, respectively. ing. The lead terminal 23 extending from the excitation electrode 22 on the upper surface side of the crystal substrate 21 extends to the edge of the crystal substrate and terminates, and the lead terminal 23 extending from the excitation electrode on the lower surface side extends to the same edge of the crystal substrate. By being folded upward and extended, the edges of both lead terminals 23 are arranged along the same edge of the quartz substrate.
The IC component 30 is provided on the lower surface of the IC component main body 31 with an area that can be placed between two opposing upper surfaces 6a of the annular outer wall 6 and connected to each connection pad 7 by a bump 40. A first component side terminal 32 and a second component side terminal 33 provided on the lower surface of the IC component main body 31 and electrically and mechanically connected to each lead terminal 23 of the crystal resonator element by a bump 41. ing. In order to mount and fix the IC component 30 so as to straddle the two upper surfaces 6a, the IC component 30 needs to have a plane area exceeding the plane area of the recess 9 as in the related art. Since there is no need to reduce the size of the IC component in order to store it in the recess 9, a large type IC component 30 can be applied, and the range of component selection can be expanded.
[0006]
A characteristic configuration of the crystal oscillator 1 of the present invention is that the crystal resonator element 20 is electrically and mechanically connected to and supported on the lower surface of the IC component main body 31 disposed between two opposed upper surfaces 6a of the annular outer wall 6. Thus, the point lies in that the quartz-crystal vibrating element 20 is arranged in the recess 9 inside the annular outer wall 6. That is, four first component-side terminals 32 are arranged on the lower surface of the IC component main body 31 along two opposing edges, and these first component-side terminals 32 are While being electrically and mechanically connected in a one-to-one relationship with the connection pads 7 arranged on the opposed upper surface 6 a of the annular outer wall 6, the two second component side terminals 33 are connected to the quartz crystal via the bumps 41. It is electrically and mechanically connected to the two lead terminals 23 on the main surface of the element 20 in a one-to-one relationship. In the present embodiment, the crystal resonator element 20 is not supported by a step or the like provided in the recess of the container 2 as described above, but is supported by the upper surface of the outer wall outside the recess. In this way, there is no need to provide a step in the recess, and since the IC components are supported on the upper surface of the outer wall outside the recess, a large area for mounting the IC components can be secured, but compared with the conventional container structure. Thus, a crystal oscillator having a smaller occupied area can be realized. Further, the excitation electrode 21 of the crystal resonator element 20 is not directly connected to a wiring pattern such as a connection pad provided on the container 2 side, but is directly connected only to the corresponding terminal 33 on the IC component side. . Therefore, it is not necessary to form a wiring pattern for connecting the crystal resonator element 20 and the IC component 30. As a result, the parasitic capacitance generated between the excitation electrodes of the crystal vibrating element 20, the parasitic capacitance generated between the excitation electrode and the ground, and the floating capacitance generated between the output terminal electrodes are determined by the wiring pattern inside the IC component. It is almost determined by the stray capacitance, and the overall parasitic capacitance and stray capacitance are reduced as much as possible.
According to the crystal oscillator 1 of the present invention having the above-described configuration, a large-sized IC component 30 having a plane area larger than that of the recess 9 can be accommodated in the container body. Further, the parasitic capacitance between the excitation electrodes of the crystal resonator element 1 and the parasitic capacitance of the lead terminal on the crystal resonator element side with respect to the ground terminal and the output terminal can be reduced as much as possible.
As a manufacturing procedure of the crystal unit 1, first, the second component side terminal 33 of the IC component 30 and the lead terminal 23 of the crystal resonator element 20 are joined via the bump 41 to the IC component 30. The crystal vibrating element 20 is positioned and fixed. Next, each first component side terminal 32 of the IC component 30 is connected to each connection pad 7 of each outer wall upper surface 6 a via the bump 40 so that the crystal resonator element 20 fits into the recess 9. Further, the seam ring 8 on the outer wall upper surface and the metal lid 10 are seam-welded to hermetically seal the recess 9. The metal cover 10 is connected to the mounting terminal 4 on the ground side via a conductor pattern inside the thickness of the container body 5.
When the crystal unit 1 is mass-produced by batch processing, the above procedure may be performed using a large-area container body base material in which a large number of container bodies 5 are connected in a sheet shape. Next, by making the IC component 30 include a temperature compensation circuit for compensating the frequency temperature characteristic of the crystal resonator element 20, the crystal oscillator 1 according to the above-described embodiment is made to be a temperature-compensated crystal oscillator 1 (TCXO). Can be.
FIG. 2 shows an example in which, when the crystal oscillator 1 of the present invention is of a temperature-compensated type, an adjustment terminal 50 required for adjusting the frequency-temperature characteristic and the frequency at normal temperature is arranged on the side surface of the container body 5. Is shown. Note that the adjustment terminal 50 may be provided on the bottom surface of the container body 5.
[0007]
Next, FIG. 3 is a circuit diagram of a CMOS inverter oscillator, in which a temperature compensation having a cubic function from a power supply terminal 57 is provided between a capacitor 55 constituting an oscillation circuit and a variable capacitance varicap diode 56 connected in series. If the structure of the crystal oscillator of the present invention is applied to an indirect temperature compensation type TCXO that compensates temperature characteristics by applying a voltage, the temperature compensation sensitivity of the frequency can be increased, and the dynamic range of the temperature compensation voltage is effective. Can be used.
Further, if the structure of the crystal oscillator of the present invention is applied to a VC-TCXO having a frequency voltage control function, the amount of frequency change can be further increased as compared with the conventional example.
In any case, the parasitic capacitance between the crystal oscillator terminal and the output terminal shown in the figure can be reduced as much as possible, so that a TCXO or VC- TCXO can be obtained. The parasitic capacitance of the lead terminal on the crystal resonator element side with respect to the ground terminal can be reduced as much as possible.
Next, FIG. 4 is a plan view (with a metal cover removed) of a crystal oscillator 1 according to another embodiment of the present invention. In this embodiment, each lead terminal 23 of the crystal resonator element 20 and an IC component are shown. This is an example in which the connection strength is increased by using a plurality of bumps 41, for example, two bumps 41 connecting the second component side terminal 33 on the side. In this case, for example, by increasing the area of each of the second component side terminals 33 provided on the IC component side, a plurality of bumps 41 can be used.
Further, instead of the bumps, they may be connected using another conductive member. In the above embodiment, the surface-mounted crystal oscillator is described as an example. However, it goes without saying that the present invention can be applied to a piezoelectric oscillator using a piezoelectric material other than crystal.
[0008]
【The invention's effect】
As described above, according to the present invention, in a surface mount type piezoelectric oscillator having a structure in which an IC component chipped together with a piezoelectric vibrating element is accommodated in an airtight space in a container, Narrowing of the IC component mounting area due to the formation of the step for mounting the vibrating element, and instability of the oscillation output frequency due to the parasitic capacitance of the wiring pattern connected to the excitation electrode of the piezoelectric vibrating element Can be eliminated.
That is, in the surface mount type piezoelectric oscillator according to the first aspect of the present invention, the inside of the recess is not used as a space for mounting the IC component, and the IC component is mounted across the upper surface of the outer wall located outside the recess. In addition, the size of the IC component to be used can be increased, while the recess functions only as a space for fitting and arranging the piezoelectric vibration element. Therefore, the flat area of the container can be reduced in size and thickness. In addition, since the piezoelectric vibrating element is electrically and mechanically connected and supported directly on the lower surface of the IC component, there is no wiring pattern for connection with the piezoelectric vibrating element in the recess, and transmission due to the influence of parasitic capacitance is eliminated. Instability of the output frequency can be prevented.
According to the second aspect of the present invention, each of the second component side terminals on the lower surface of the IC component main body and each of the lead terminals on the piezoelectric vibration element side are connected using a plurality of bumps. Electromechanical bonding strength of the element can be increased, and durability and reliability can be improved.
[Brief description of the drawings]
FIGS. 1A, 1B, 1C, and 1D are a plan view, an AA ′ cross-sectional view, a container body plan view, and an IC component of a surface-mount type piezoelectric oscillator according to an embodiment of the present invention. FIG.
FIG. 2 is a front view of a piezoelectric oscillator according to another embodiment of the present invention.
FIG. 3 is a diagram showing a circuit configuration of a CMOS inverter oscillator.
FIG. 4 is a plan view of a main part of a surface-mount type piezoelectric oscillator according to another embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of a conventional piezoelectric oscillator.
[Explanation of symbols]
Reference Signs List 1 crystal oscillator, 2 container, 3 bottom plate, 4 mounting terminals, 5 container body, 6 annular outer wall, 6a upper surface, 7 connection pad, 8 seam ring, 9 recess, 10 metal cover, 20 piezoelectric vibration element (crystal vibration element ), 21 piezoelectric substrate (quartz substrate),
22 excitation electrode, 23 lead terminal, 30 IC component, 31 IC component main body, 32 first component side terminal, 33 second component side terminal, 40 bump, 41 bump, 50 adjustment terminal, 55 capacitor, 56 varicap Diode, 57 power supply terminal.

Claims (2)

A bottom plate made of an insulating material having a mounting terminal for surface mounting on an outer bottom portion, an annular outer wall made of an insulating material integrated on the bottom plate, connection pads for mounting a plurality of IC components disposed on the upper surface of the annular outer wall, And a container main body having an upper surface of the annular outer wall and a seam ring protruding from the connection pads on an outer diameter side, and a fixing member on the seam ring of the container main body, thereby forming an inner side of the annular outer wall. A container with a metal lid for sealing the recess,
A piezoelectric vibration element having an excitation electrode and a lead terminal extending from the excitation electrode on a main surface of the piezoelectric substrate,
An IC component main body having an area that can be placed and mounted between opposed upper surfaces of the annular outer wall, a first component side terminal provided on a lower surface of the IC component main body and connected to each of the connection pads, and the IC An IC component provided on the lower surface of the component body and having a second component side terminal electrically and mechanically connected to each lead terminal of the piezoelectric vibration element. A surface-mounted piezoelectric oscillator, wherein the piezoelectric vibrating element is arranged in a recess inside the annular outer wall by supporting the element. 2. The surface mounting according to claim 1, wherein each of the second component side terminals on the lower surface of the IC component main body and each of the lead terminals on the piezoelectric vibration element side are connected using a plurality of bumps. Type piezoelectric oscillator.

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