JP2010166626A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dissolve faulty adhesion that an adhered part is stripped by the weight of a piezoelectric vibration element during a period in which a retaining force by a conductive adhesive agent is weak since the adhesive agent is in an uncured condition upon supporting one end of the piezoelectric vibration element on a small-size circuit component such as a chip component or the like through the conductive adhesive agent. <P>SOLUTION: The piezoelectric device is provided with a package body 21, equipped with an outside electrode on a bottom part and equipped with a conductive pad 21b for IC mounting which is conductive with the outside electrode on the upper part thereof, an IC chip 22 connected to the upper part of the conductive pad of the package body for conductive connection, the piezoelectric vibration element 23 with at least one end rim supported by the upper electrode 22c above the IC chip through the conductive adhesive agent B, and a rid member 24 for air-tight sealing of the upper surface of a package body comprising the IC chip and the piezoelectric vibration element, wherein the IC chip is provided with a length exceeding a distance from one end rim of the piezoelectric vibration element to the position of center of gravity of the same. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement of a surface-mounted piezoelectric oscillator, and more particularly to a surface-mounted piezoelectric oscillator that achieves miniaturization by simplifying the configuration of a piezoelectric oscillator that includes a piezoelectric vibration element and circuit components that constitute an oscillation circuit.

  Due to the rapid progress in cost reduction and miniaturization accompanying the widespread use of mobile communication devices such as cellular phones, the price of piezoelectric oscillators such as crystal oscillators used as frequency control devices in these communication devices is also reduced. There is an increasing demand for downsizing and thinning. In response to such demands, in addition to crystal resonators, an oscillation circuit including a frequency adjustment circuit, a frequency temperature compensation circuit, etc., is integrated, and IC components are housed in a single package for compactness. I am trying.

[First Conventional Example]
In the conventional piezoelectric oscillator shown in FIG. 5, a circuit component 4 formed as an IC is mounted on the inner bottom surface of a package body 1 having a recessed portion 2 and a stepped portion 3 by a flip chip method or the like, and on the inner wall of the recessed portion 2. One end of the piezoelectric vibration element 5 is cantilevered and supported by the conductive adhesive B on the electrode on the provided step 3, and the metal lid 6 is fixed to the upper surface of the outer frame of the package body 1 to hermetically seal the recess 2. (For example, JP-A-7-336179). This piezoelectric oscillator is designed to be compact by mounting the circuit component 4 on the inner bottom surface in the same recessed portion 2 and supporting it on the step 3 so that the piezoelectric vibration element 5 is positioned immediately above the circuit component 4. ing.
However, this type of piezoelectric oscillator has a structure in which the step 3 protrudes inward from the inner wall of the recessed portion, and avoids contact with the step 3 when the circuit component 4 is mounted on the inner bottom surface of the recessed portion. For this reason, since it is necessary to secure a sufficient space between the step 3 and the circuit component, there is a limit in reducing the planar area of the entire package. Therefore, when further downsizing of the piezoelectric oscillator is required, there is a problem that the piezoelectric oscillator cannot be fully handled.

FIG. 6 is a schematic diagram of a piezoelectric oscillator described in Japanese Patent Application Laid-Open No. 10-173475. A chip component (chip capacitor or chip resistor) mounted on the inner bottom surface of the ceramic package body 11 having the recessed portion 12 is shown. ) One end of the piezoelectric vibration element 14 is electrically and mechanically fixed to the upper surface of the sheet 13 with a conductive adhesive B or the like, and a metal lid 15 is fixed to the upper surface of the outer frame of the package body 11 by seam welding or the like.
However, in this conventional example, since the structure is supported by the chip component 13 having a dimension that is significantly shorter than the longitudinal length of the piezoelectric vibration element 14, one end of the piezoelectric vibration element 14 is attached to the chip component 13. When the conductive adhesive B is bonded and fixed in a horizontal orientation on the upper surface, hold one end of the piezoelectric vibration element 14 using a jig or the like until the conductive adhesive B is cured. It is necessary to keep it in a horizontal position. If the force for pressing the piezoelectric vibration element is released before the conductive adhesive B is cured, the tip portion hangs down due to the weight of the piezoelectric vibration element, and the conductive adhesive is applied from the one end of the piezoelectric vibration element and the upper surface of the chip component 13. May peel off, resulting in poor adhesion or dropping of the piezoelectric vibration element. In order to solve such a problem, a complicated procedure in which one end of the piezoelectric vibration element has to be pressed onto the chip component until the adhesive is cured is required. However, in the process of mass production by batch processing, incorporating the work of continuously pressing the piezoelectric vibration elements in all the packages has been a cause of lowering productivity.
In this conventional example, one end of the piezoelectric vibration element is fixed at a position on the right side of the center of the chip component 13. In other words, since the width W2 where the piezoelectric vibration element and the chip component 13 overlap is short, a large package body 11 is used as long as the chip component 13 protrudes to the left from one end of the piezoelectric vibration element. This is a factor that hinders the miniaturization of the oscillator.

[Second Conventional Example]
Next, as another piezoelectric oscillator, for example, in Japanese Patent Laid-Open No. 2000-151283, a piezoelectric vibration element is accommodated in an upper concave portion of an H-shaped ceramic package having a concave portion on the upper and lower sides and hermetically sealed. On the other hand, there is disclosed a structure in which circuit components made into an IC are mounted on the ceiling surface of the lower recessed portion.
Further, this publication discloses a two-stage stacked piezoelectric oscillator in which a package in which circuit components are mounted and a package in which a piezoelectric vibration element is accommodated are coupled in a vertical position relationship. Further, the circuit component 4 is accommodated in the recessed portion 2 of the package body 1 as shown in FIG. 5, while a packaged piezoelectric vibrator (not shown) is mounted on the step 3, and the recessed portion 2 of the package body 1 is further mounted. An oscillator of the type in which is closed by a metal lid 6 is also known.
Each of the piezoelectric oscillators is common in that the planar area of the entire piezoelectric oscillator is reduced by arranging circuit components and piezoelectric vibration elements in a vertical relationship within the package. Furthermore, a structure common to these oscillators is that the concave portion is hermetically sealed by fixing a metal lid to the upper surface of the outer frame constituting the outer wall portion of the concave portion of the package by seam welding or the like. .
However, no matter how the outer shape of the package body is reduced, the joint area of the sealing portion between the upper surface of the outer frame and the metal lid constituting the outer wall of the package body is reduced, in other words, the upper surface of the outer frame. Since there is a limit to the reduction of the width direction dimension (W1 in FIG. 5), when the package main body is downsized to reduce the capacity of the recessed portion, the area of the piezoelectric vibration element is reduced accordingly. There is a need to.
However, when the area of the piezoelectric vibration element is reduced, the conductive adhesive used when the piezoelectric vibration element is connected to the package is in a state close to the excitation electrode, so that the vibration energy is concentrated on the excitation electrode portion. Cannot be performed, and the characteristics of the oscillator are adversely affected. Furthermore, since the ceramic package and a piezoelectric substrate made of a piezoelectric material such as quartz are connected by a conductive adhesive, thermal distortion occurs in the piezoelectric vibration element due to the difference in thermal expansion coefficient of each material, which adversely affects the characteristics. .

JP 7-336179 A JP-A-10-173475 JP 2000-151283 A

The present invention has been made in view of the above, and a first problem corresponding to the first conventional example is that one end of a piezoelectric vibration element is supported by a conductive adhesive on a small circuit component such as a chip component. In this case, the problem is that the adhesive part peels off due to the weight of the piezoelectric vibration element during the period when the holding force by the conductive adhesive is weak because it is in an uncured state. In other words, an object of the present invention is to increase productivity by eliminating the need for a complicated operation of continuing pressing with a jig or the like until the adhesive is cured in order to prevent peeling of the bonded portion. It is another object of the present invention to solve the problem that a part of the chip component protrudes laterally from the piezoelectric vibration element, thereby increasing the size of the package.
Next, a second problem corresponding to the second conventional example is that when the circuit component and the piezoelectric vibration element are arranged in a vertical positional relationship and packaged, if the package is further reduced in size, It is necessary to reduce the area, and as a result, to solve the problem that the characteristics of the piezoelectric vibration element are adversely affected.

A first embodiment of the present invention includes a package body having a conductive pad for mounting an IC, an IC chip that is conductively connected to the conductive pad, and an upper surface of the IC chip that extends from an edge of the IC chip. A piezoelectric vibration element mounted in a hung manner, and a lid member that is fixed to the package body by a sealing member and hermetically seals the IC chip and the piezoelectric vibration element. And an excitation electrode formed on the vibration part, a thick annular part integrally holding the outer peripheral edge of the vibration part, and provided on the lower surface of one end edge of the annular part and electrically connected to the excitation electrode; And a pad electrode that is electrically and mechanically connected to an upper electrode formed on the upper surface of the IC chip.
The second embodiment of the present invention is the piezoelectric device according to the first embodiment in which the center of gravity of the piezoelectric vibration element is located inside the outer shape of the IC chip in plan view.
In the third embodiment of the present invention, the pad electrode of the piezoelectric vibration element is electrically and mechanically connected to the upper electrode on the upper surface of the IC chip by a conductive adhesive, solder, or a conductor bump. The piezoelectric device according to the first or second embodiment.
According to a fourth embodiment of the present invention, a step is provided on the package body that projects directly below a portion of the piezoelectric vibrator overhanging from the IC chip, and the height of the step is set to the height of the IC chip. It is the piezoelectric device of any one of the 1st thru | or 3rd embodiment made higher than this.

Application Example 1 A surface-mount piezoelectric oscillator according to this application example includes a package body having an external electrode at the bottom and a conductive pad for mounting an IC that is electrically connected to the external electrode at the top. An IC chip that is conductively connected on a conductive pad; a piezoelectric vibration element having at least one edge supported by a conductive adhesive or a conductor bump with respect to an upper electrode on the IC chip; and the IC chip and the piezoelectric vibration element. And a lid member that hermetically seals the upper surface of the package body including the IC chip, wherein the IC chip has a length exceeding a distance from the one end edge of the piezoelectric vibration element to a position of the center of gravity.
Application Example 2 The piezoelectric vibration element includes a piezoelectric substrate having an ultra-thin vibrating portion and an annular thick portion that integrally holds the outer periphery of the vibrating portion, and an excitation formed on the vibrating portion of the piezoelectric substrate. An electrode and a pad electrode disposed on the lower surface of the annular thick portion and electrically connected to the excitation electrode, and the pad electrode provided on the lower surface of the annular thick portion is connected to an electrode on the upper part of the IC chip and an electrical machine The surface-mount piezoelectric oscillator according to Application Example 1, wherein the surface-mount piezoelectric oscillator is connected in a mechanical manner.
Application Example 3 The piezoelectric vibration element includes a strip-shaped piezoelectric substrate, an excitation electrode formed on a vibration portion of the piezoelectric substrate, a pad electrode that is disposed at an appropriate position on the lower surface of the piezoelectric substrate, and is electrically connected to the excitation electrode. The surface mount piezoelectric oscillator according to Application Example 1, wherein the pad electrode is electrically and mechanically connected to the upper electrode on the IC chip.

Application Example 4 In the surface-mount piezoelectric oscillator according to the application example described above, the piezoelectric vibration element is disposed so as to substantially cover the entire length of the IC chip. The surface-mount piezoelectric oscillator according to any one of Application Examples 1 to 3.
Application Example 5 In the surface mount piezoelectric oscillator according to the application example described above, one end edge of the piezoelectric vibration element is connected to an electrode on the top of the IC chip, whereby the other end edge of the piezoelectric vibration element is separated from the edge of the IC chip. In the over-mounted surface-mount type piezoelectric oscillator, a step projecting just below the other end edge of the piezoelectric vibration element is disposed on the package body, and the height of the step is made higher than the height of the IC chip. The surface-mount piezoelectric oscillator according to any one of Application Examples 1 to 4, wherein the surface-mount piezoelectric oscillator is provided.
Application Example 6 A silicon substrate including circuit elements constituting an oscillation circuit, an external electrode provided on the bottom of the silicon substrate, and an upper electrode disposed on the top surface of the silicon substrate and connected to the external electrode. The IC chip and the silicon substrate have a planar shape that matches with or aligns with the inside of the silicon substrate, and has a concave portion on the top and bottom surfaces, an excitation electrode on the vibration portion on the inner bottom surface of the concave portion, and the upper electrode And a lid having a planar shape that matches the piezoelectric vibrating element, and a piezoelectric plate having a planar shape that matches the piezoelectric vibrating element. A surface-mount type piezoelectric oscillator characterized in that a lid is sequentially stacked to join the upper electrode and the pad electrode, and further the lid is joined to the upper surface of the piezoelectric vibrator.
Application Example 7 The surface mount piezoelectric oscillator according to any one of Application Examples 6, wherein an outer surface of the piezoelectric oscillator excluding the external electrode is covered with an insulating film.
Application Example 8 The surface mount piezoelectric oscillator according to Application Example 5 or 6, wherein the upper surface of the piezoelectric vibration element is a full surface electrode.

Since it comprised as mentioned above, according to this invention, when supporting the one end part of a piezoelectric vibration element on a small circuit components, such as a chip component, with a conductive adhesive, since it is in an unhardened state, it is conductive. During the period when the holding force by the adhesive is weak, it is possible to eliminate the problem that the bonded portion peels due to the weight of the piezoelectric vibration element. In other words, it is possible to increase productivity by eliminating the complicated work of keeping pressing with a jig or the like until the adhesive is cured in order to prevent peeling of the bonded portion. In addition, since a part of the chip component protrudes laterally from the piezoelectric vibration element, it is possible to solve the problem that the package becomes larger by that amount.
Further, when the circuit component and the piezoelectric vibration element are arranged in a vertical position relationship and packaged, if the package is to be further reduced in size, the area of the piezoelectric vibration element needs to be reduced. As a result, the piezoelectric vibration element It is possible to solve the problem of adversely affecting the characteristics.

(A) is a longitudinal cross-sectional view of the surface-mounted piezoelectric oscillator according to the first embodiment of the present invention, and (b) is a diagram showing a modified embodiment in the case of cantilevering a crystal resonator element. (A) is a longitudinal cross-sectional view of the modified embodiment of the crystal oscillator of FIG. 1 (a), (b) is a longitudinal cross-sectional view of the modified embodiment of FIG. 1 (b). The longitudinal cross-sectional view of the modification of embodiment shown in FIG. 1 or FIG. (A) is a perspective view of a surface-mounted piezoelectric oscillator according to a second embodiment of the present invention, (b) is an exploded perspective view, (c) is a cross-sectional view along AA, and (d) and (e) are modified embodiments. Sectional drawing of a form. The longitudinal cross-sectional view of the oscillator of a prior art example. The longitudinal cross-sectional view of the oscillator of another prior art example.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
[First Embodiment]
FIG. 1A is a longitudinal sectional view of a surface-mount piezoelectric oscillator according to the first embodiment of the present invention.
This surface-mount type piezoelectric oscillator is, for example, a crystal oscillator 20, and this crystal oscillator 20 constitutes an oscillation circuit including a frequency adjustment circuit, a frequency temperature compensation circuit, and the like on a package body (printed circuit board) 21 made of ceramic or the like. A flat plate IC chip 22 is mounted, a crystal vibration element 23 is mounted on the upper surface of the IC chip 22, and the upper surface of the printed circuit board 21 including the IC chip 22 and the crystal vibration element 23 is sealed with a lid member 24. .
The package body 21 made of a ceramic plate or the like has an external electrode 21a on the lower surface and a conductive pad 21b for mounting an IC on the upper surface.
The IC chip 22 is a bare chip, and each circuit element constituting an oscillation circuit is formed in the silicon substrate 22a by LSI technology, and the external electrode 22b is provided on the lower surface of the silicon substrate 22a, and the upper electrode 22c is provided on the upper surface. Yes.
The quartz resonator element 23 includes a quartz substrate 25 including an ultra-thin vibrating portion 25a and a thick annular thick portion 25b that integrally holds the outer peripheral edge of the vibrating portion 25a, and a surface of the vibrating portion 25a of the quartz substrate 25. Excitation electrodes 26 formed on the back surface, lead electrodes 26a drawn from the respective excitation electrodes 26, and pad electrodes 26b connected to the respective excitation electrodes 26 via the respective lead electrodes 26a and positioned on the lower surface of the annular thick portion 25b. And comprising. The pad electrode 26b and the upper electrode 22c of the IC chip 22 are made to face each other and are electrically and mechanically connected by a connection means B such as a conductive adhesive, solder, or bump.
The lid member 24 is made of metal or ceramic, and its lower end surface is soldered on the ground electrode 21c on the package body 21 in order to hermetically seal the space on the package body 21 including the IC chip 22 and the crystal resonator element 23. The sealing member is fixed so as to maintain an airtight state.
Of the pad electrodes 26b provided on the lower surface of the annular thick portion as shown in the figure, when two pad electrodes in a positional relationship facing each other across the vibrating portion 25a are fixed on the IC chip 22, the IC chip 22 It is necessary to set the lateral dimension to a length substantially equal to that of the crystal resonator element 23. In this case, the depth dimension of the IC chip 22 may be equal to or greater than the depth dimension of the crystal resonator element 23, but may be narrow as long as it can be mounted without being tilted by the crystal resonator element 23.
On the other hand, as shown in FIG. 5B, when a cantilever support structure in which only one pad electrode 26b is fixed on the IC chip 22 is adopted, the lateral dimension of the IC chip 22 is as shown in the figure. In addition, it may be significantly shorter than the lateral dimension of the crystal resonator element 23 or may be substantially equivalent to the crystal resonator element 23.

That is, FIG. 1B shows a modified embodiment in the case where the quartz resonator element is cantilevered. In this case, the length L1 of the IC chip 22 is from the left edge of the quartz resonator element 23 to the center of gravity. It can be shortened to the corresponding length. That is, the length of the IC chip 22 is about ½ of the length L2 of the crystal resonator element 23 or the center of gravity of the crystal resonator element 23 with one end (left end) supported by the conductive adhesive. By shortening the length, the pad electrode 26b (only at the left end portion of the crystal resonator element is mounted while stably placing the crystal resonator element 23 on the IC chip before the conductive adhesive is cured. It is possible to carry out the adhesive fixing of the arrangement. Therefore, even when mass production is performed by batch processing, a complicated process of waiting for the adhesive to cure while continuing to hold the adhesive portions of the crystal resonator elements 23 on all the IC chips 22 can be omitted, and mass productivity is improved. be able to. Also, it is possible to use various types of IC chips with different lateral dimensions as the IC chip to be used, and there is no need to use an IC chip having an area equivalent to that of a quartz-crystal vibrating element. The degree increases.
In this embodiment, a flat printed board is used as the package body 21, but it is needless to say that a box-shaped package body having a concave portion on the upper surface may be used. In this case, the upper surface of the package body will be closed by a flat metal lid.
In addition, when the crystal resonator element 23 is fixed on the IC chip 22 with the conductor bump, it does not need the curing time as in the case of the conductive adhesive. Positioning on the IC chip is preferable because the weight applied to the connection point between the IC chip 22 and the package body 21 is uniform, and the left end of the crystal resonator element 23 is positioned as far as possible to the left end of the IC chip 22. By reducing the size, the overall size can be reduced.

According to the crystal oscillators according to the embodiments shown in FIGS. 1A and 1B, the crystal resonator element is directly mounted on the IC chip mounted on the package body. It is not necessary to project a step for supporting the vibration element, and it is not necessary to secure a space for incorporating circuit components between the steps, so that the planar shape of the package can be reduced.
Further, the length L1 of the IC chip 22 may be small enough to have a length exceeding the distance from one end edge (left end edge in the figure) of the piezoelectric vibration element 23 to the position of the center of gravity. The range of selection is expanded, and the degree of freedom in design is increased.
Further, the amount of protrusion of the IC chip 22 from the end edge of the piezoelectric vibration element 23 is reduced as much as possible, and the piezoelectric vibration element 23 is assembled so as to substantially cover the entire length of the IC chip 22. Thus, the amount of lateral protrusion beyond the dimension can be reduced, and the plane area of the package can be reduced.
When one end edge of the crystal resonator element 23 is fixed on the IC chip with a conductive adhesive and cantilevered, even if the crystal resonator element 23 is held in a horizontal posture parallel to the upper surface of the IC chip at the time of bonding, The one end edge on the non-adhesive side is fixed in a slightly tilted upward direction due to the upward stress generated in the adhesive during the curing of the adhesive. For this reason, in any case of FIGS. 1A and 1B, after the adhesive is cured, the lower surface excluding the left end edge of the annular thick portion 23b of the crystal resonator element 23 is separated from the upper surface of the IC chip 22. Held in. Therefore, there is no problem that the free vibration of the vibration part is prevented by the contact between the upper surface of the IC chip and the lower surface of the annular thick part in a wide range.

Next, FIG. 2A is a longitudinal sectional view of a modified embodiment of the crystal oscillator of FIG. 1A, and a rectangular (flat plate) crystal substrate is used as the crystal resonator element 23 mounted on the IC chip 22. The point which used what consists of is different from the thing of Fig.1 (a).
That is, the crystal resonator element 23 used in the crystal oscillator according to this embodiment includes a flat plate crystal substrate 27, excitation electrodes 27a formed on the front and back surfaces of the crystal substrate 27, and from each excitation electrode 27a toward both ends. The lead electrode 27b is drawn out, and the pad electrode 27c is connected to each lead electrode 27b and disposed on the lower surface of the crystal substrate 27.
In this embodiment, the case where the pad electrodes 27c respectively disposed at the two opposing edges of the crystal resonator element 23 are bonded and fixed to the upper surface of the IC chip has been described. However, the two pad electrodes 27c are disposed along one edge. The pad electrodes 27c arranged at the one end edge may be cantilevered by being fixed to the upper surface of the IC chip with a conductive adhesive. In this case, during the bonding operation, the lower surface of the free end portion of the crystal resonator element 23 is brought into contact with the upper surface of the IC chip, and each pad electrode 27c provided at one end edge is fixed to the upper electrode 22c by the conductive adhesive. Due to the upward stress generated in the adhesive during the curing of the crystal, the free end of the crystal resonator element is lifted upward and fixed in a non-contact state with the IC chip 22, so that the free vibration of the crystal resonator element 23 is There is no hindrance by the IC chip 22.
As for other structural features, effects, etc., what has been described with reference to FIG.

Next, FIG. 2 (b) is a modified embodiment of FIG. 1 (b), and a quartz crystal resonator element using an IC chip 22 having a dimension L1 that is significantly shorter than the overall length L2 of the flat plate-like crystal resonator element 23. The structure which supported cantilever 23 is characteristic.
That is, FIG. 2B shows a modified embodiment in which the strip-shaped crystal resonator element 23 is cantilevered. In this case, the length L1 of the IC chip 22 is from the left edge of the crystal resonator element 23. It can be shortened to a length corresponding to the distance to the center of gravity.
That is, the length of the IC chip 22 is about ½ of the length L2 of the crystal resonator element 23 or the center of gravity of the crystal resonator element 23 with one end (left end) supported by the conductive adhesive. By shortening the length, it is possible to carry out adhesive fixing of the pad electrode 26b (arranged only at the left end of the crystal resonator element) with a conductive adhesive while stably placing the crystal resonator element 23 on the IC chip. It becomes possible.
That is, in this case, the lower surface of the crystal resonator element 23 is located at the position of the center of gravity when placed on the right upper surface of the IC chip 22 in the drawing except the portion protruding rightward from the right edge of the IC chip 22. Is present on the IC chip, so that the crystal resonator element 23 is not pressed onto the upper surface of the IC chip 22 by a special jig or the like before the conductive adhesive is cured. 23 does not slip off, and there is no possibility of the adhesive part peeling off. Therefore, even when mass production is performed by batch processing, a complicated process of waiting for the adhesive to cure while continuing to hold the adhesive portions of the crystal resonator elements 23 on all the IC chips 22 can be omitted, and mass productivity is improved. be able to. Also, it is possible to use various types of IC chips with different lateral dimensions as the IC chip to be used, and there is no need to use an IC chip having an area equivalent to that of a quartz-crystal vibrating element. The degree increases.
In this embodiment, a flat printed board is used as the package body 21, but it is needless to say that a box-shaped package body having a concave portion on the upper surface may be used. In this case, the upper surface of the package body will be closed by a flat metal lid.

Next, FIG. 3 is a modification of the embodiment shown in FIG. 1 or FIG. 2, and this surface-mount type piezoelectric oscillator has an external electrode 21a on the bottom and a package body 21 having a recess 21A on the top. And an IC chip 22 mounted on a conductive pad 21b provided on the inner bottom surface of the recessed portion 21A, and an upper edge 22c on the IC chip 22 using a conductive adhesive B (or bump), and cantilevering one end edge. It has a supported crystal resonator element 23 and a lid member 24 that is fixed to the upper surface of the outer frame of the package body 21 and hermetically seals the recessed portion 21A.
The crystal resonator element 23 may be either a type in which the thin vibrating portion shown in FIG. 1 is supported by an annular thick portion, or a strip type shown in FIG.
A characteristic configuration of the oscillator according to this embodiment is that a step 21B is disposed on one inner wall of the recessed portion 21A of the package body 21 and the other end edge of the crystal resonator element 23 overhangs from the end edge of the IC chip 22. This is the point that the upper surface of the step 21B is positioned immediately below. The height H2 of the step 21B is set to be slightly higher than the height H1 of the IC chip 22 mounted on the inner bottom surface of the recessed portion.
With this configuration, when the crystal resonator element 23 is mounted on the IC chip 22, the one end edge is bonded to the upper electrode 22c with the lower surface of the other end edge overhanging placed on the step 21B. Work can be done. For this reason, it is possible to eliminate problems such as the easily peeled excitation electrodes 26a and 27a formed on the lower surface of the crystal resonator element 23 being rubbed against the upper surface of the IC chip and damaged.
In the state where the conductive adhesive B is cured, the other end portion of the crystal resonator element is urged upward by the upward stress generated in the conductive adhesive. The other end is held in a state sufficiently separated from the upper surface of the step 21B.

[Second Embodiment]
4A, 4B, and 4C are a perspective view, an exploded perspective view, and an AA cross-sectional view of a surface-mount piezoelectric oscillator according to a second embodiment of the present invention.
This surface-mount type piezoelectric oscillator is, for example, a crystal oscillator 31. The crystal oscillator 31 has a crystal resonator element 33 on a flat-plate IC chip 32 constituting an oscillation circuit including a frequency adjustment circuit, a frequency temperature compensation circuit, and the like. A lid 34 made of a quartz plate is sequentially laminated and integrated.
The IC chip 32 is a bare chip, and each circuit element constituting an oscillation circuit is formed on the silicon substrate 40 by LSI technology, and an external electrode 41 is provided on the lower surface of the silicon substrate 40 and an upper electrode 42 is provided on the upper surface. Yes.
The crystal vibrating element 33 has a configuration in which the peripheral portion of the ultrathin vibrating portion 45 is integrally supported by a thick annular thick portion 46, and excitation electrodes 47 and 48 are provided at the front and back center portions of the vibrating portion 45. Further, pad electrodes 47b and 48b are arranged at the terminal portions of the lead terminals 47a and 48a formed and led out from the excitation electrodes 47 and 48, respectively. The pad electrodes 47 b and 48 b are located on the lower surface of the annular thick part (thick part) 46. The crystal resonator element 33 is sized and shaped so as to be in close contact with the upper surface of the IC chip 32 in an aligned state, and the pad electrodes 47b and 48b provided on the lower surface of the annular thick portion 46 are provided with IC The upper electrodes 42 on the chip 32 are arranged so as to correspond one-to-one.
The lid 34 made of a quartz plate or glass is set in size and shape so as to be in close contact with the upper surface of the quartz vibrating element 33.
The silicon substrate 40 constituting the IC chip 32, the crystal resonator element 33, and the lid 34 made of a crystal plate are all materials having the same thermal expansion coefficient.
In this crystal oscillator 31, the crystal resonator element 33 and the lid 34 are sequentially stacked on the IC chip 32, and the upper electrode 32 and the pad electrodes 47b and 48b are joined by a binder such as a conductive adhesive or solder, a gold bump, or the like. Further, the lid 34 is completed by bonding or bump fixing to the upper surface of the annular thick portion 46. In the case of manufacturing using a large area IC chip base material, a crystal resonator element base material, and a base material for a lid by batch processing, after attaching each base material and bonding the required parts, Individual crystal oscillators 21 are obtained by cutting.

Note that when the IC chip 32, the crystal resonator 33, and the lid 34 are bonded together as described above, fine gaps are generated between the members, and airtightness in the upper and lower recesses of the crystal resonator element 33 is reduced. There is a risk of becoming insufficient. Therefore, a silicon (Si) -based thin film (insulating film) such as SiO2 is uniformly deposited on the entire outer surface of the completed crystal oscillator (excluding the external electrode 41 of the IC chip 32) by a technique such as vapor deposition and sputtering. Seals the minute gaps scattered in the interior to keep the airtightness inside. Further, it is also effective in covering and insulating the portion where the conductor excluding the external electrode 41 is exposed on the outer surface with a silicon-based thin film. In such a configuration, the IC chip, the crystal resonator element, the lid, and the vapor deposition film are silicon-based materials, and their respective thermal expansion coefficients are substantially equal, so that the vapor deposition film cracks due to temperature changes such as heating, It does not happen that airtightness decreases.
Alternatively, an insulating resin film (insulating film) may be mold-coated on the entire outer surface of the oscillator chip except for the external electrode 41 of the IC chip 32 to seal minute gaps, and the exposed conductor portion may be insulated. Good. Moreover, the bonding strength between the members can be increased by coating with the mold.
Further, as shown in FIG. 4D, one surface of the crystal resonator element may be a full-surface electrode 47A, or both the lid and the crystal resonator element may have a recess on one surface as shown in FIG. Good. Needless to say, the sizes of the IC chip and the crystal resonator element do not necessarily match.

According to the oscillator of the present invention having the above-described configuration, since a configuration in which a metal lid is fixed by welding to the upper surface of the outer frame of the package main body having the recessed portion as shown in FIG. The area corresponding to the total width of the oscillators can be reduced, and the plane area of the entire oscillator can be reduced. In addition, since the size reduction of the oscillator in the present invention does not involve reduction in the area of the crystal resonator element, the conductive adhesive as described in the conventional example interferes with the excitation electrode to prevent the concentration of vibration energy and The problem of deteriorating characteristics is eliminated. Further, since the IC chip 32, the quartz resonator element 33, and the lid 34 are all made of a silicon-based material, that is, silicon, quartz, glass, etc., their thermal expansion coefficients are almost equal, and conductive adhesive, solder, etc. Thus, when the members are joined together, the resonance frequency of the crystal resonator element does not fluctuate due to thermal distortion caused by cooling of the conductive adhesive or the like.
Further, as shown in the figure, the IC chip 32, the crystal resonator element 33, and the lid 34 are simply overlapped and joined to each other, so that they are suitable for mass production by batch processing. In other words, a large area IC chip base material, a large area crystal resonator element base material, and a large area lid base material are stacked in a state in which the positional relationship of individual pieces included in each base material is aligned. Oscillators are completed by joining the required parts and then dividing them into individual pieces, and then forming the required thin film, molding resin coating, etc. on the outer surfaces of the individual oscillators.

20 crystal oscillator, 21 package body (printed circuit board), 21a external electrode, 21b conductive pad, 22 IC chip, 22a silicon substrate, 22b external electrode, 22c upper electrode, 23 crystal vibration element, 24 lid member, 25 crystal substrate, 25a Vibrating part, 25b annular thick part, 26 excitation electrode, 26a lead electrode, 26b pad electrode, 27 quartz substrate, 27a excitation electrode, 27b lead electrode, 27c pad electrode, 31 crystal oscillator, 32 IC chip, 33 quartz vibrating element, 34 Lid, 40 Silicon substrate, 41 External electrode, 42 Upper electrode, 45 Vibration part, 46 Annular thick part, 47 Excitation electrode.

Claims (4)

A package body with a conductive pad for mounting an IC;
An IC chip conductively connected to the conductive pad;
A piezoelectric vibration element mounted on the upper surface of the IC chip overhanging from an edge of the IC chip;
A lid member fixed to the package body by a sealing member and hermetically sealing the IC chip and the piezoelectric vibration element;
With
The piezoelectric vibration element is
A vibrating portion, an excitation electrode formed on the vibrating portion, a thick annular portion that integrally holds the outer peripheral edge of the vibrating portion, and an electrical connection with the excitation electrode provided on the lower surface of one end edge of the annular portion And a pad electrode electrically and mechanically connected to the upper electrode formed on the upper surface of the IC chip.   2. The piezoelectric device according to claim 1, wherein the center of gravity of the piezoelectric vibration element is located inside the outer shape of the IC chip in plan view.   The pad electrode of the piezoelectric vibration element is electrically and mechanically connected to the upper electrode on the upper surface of the IC chip by a conductive adhesive, solder, or a conductor bump. Or the piezoelectric device of 2.   A step projecting directly below a portion of the piezoelectric vibrator overhanging from the IC chip is disposed on the package body, and the height of the step is made higher than the height of the IC chip. Item 4. The piezoelectric device according to any one of Items 1 to 3.

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