JP2006211329A - Piezoelectric device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device in which an area for mounting a mother circuit board can be reduced while maintaining oscillation characteristic. <P>SOLUTION: The piezoelectric device has a structure in which a support substrate electrically connected to a first external connection electrode terminal of a casing and a lid is additionally attached on the casing. The manufacturing method additionally attaches the support substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric device such as a piezoelectric vibrator, a piezoelectric oscillator, or a surface acoustic wave filter used in an electronic device such as a portable communication device or an electronic computer, and a manufacturing method thereof.

  Conventionally, a piezoelectric vibrator in which electrodes are formed on both main surfaces of a piezoelectric element plate are mounted in a package, or an integrated circuit element having a built-in piezoelectric vibration element and an oscillation circuit is mounted in the same package. Piezoelectric oscillators, or piezoelectric devices such as piezoelectric filters and surface acoustic wave filters that separate specific frequency bands are widely used in electronic devices such as portable communication devices and electronic computers. In recent years, piezoelectric devices having a shape corresponding to surface mounting have been developed, and with the miniaturization of electronic equipment, these piezoelectric devices are also being miniaturized.

  As an example of such a conventional piezoelectric device, FIG. 7 shows a crystal resonator using crystal as a piezoelectric material. A pair of element connection electrode pads are provided on the bottom surface of the container body 21 in the recessed space. On this element connection electrode pad, there is mounted a crystal resonator element 22 having a pair of excitation electrodes electrically connected via a conductive adhesive on the front and back main surfaces. A seal ring 23 is attached to the top of the side wall of the surrounding container body 21. A metal lid 24 is placed on the seal ring 23, and the seal ring 23 and the lid 24 are joined by seam welding or the like, thereby hermetically sealing the mounting space (recessed space) of the crystal resonator element 22. This is a crystal resonator 20. (For example, see Patent Document 1 below.)

  In the crystal resonator 20, a variable voltage from the outside is applied between the excitation electrodes of the crystal resonator element 22 through an input / output terminal provided on the lower surface of the container body 21 and an external connection electrode terminal 25 such as a ground terminal. Then, excitation vibration is caused at a predetermined frequency according to the characteristics of the crystal resonator element 22, and a reference signal having a predetermined frequency is oscillated and output by an external oscillation circuit based on the resonance frequency. Such a reference signal is used as a clock signal or the like in an electronic device such as a portable communication device.

The following documents are disclosed about the piezoelectric device including the above-described crystal resonator and the like.
JP 2001-274649 A JP 2004-236183 A

  In addition, the applicant did not come to discover prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

  However, along with the increase in functionality of portable communication devices and the like, the number of electronic components mounted on the mother circuit board of the device has increased, and the mounting area of the mother circuit board given to the piezoelectric device tends to further decrease. . For this reason, there is a demand for further miniaturization of the piezoelectric device, but when the piezoelectric device is miniaturized, the piezoelectric vibration element mounted inside the piezoelectric device is also miniaturized. The crystal impedance (CI) value of a crystal resonator element, which is one of the piezoelectric resonator elements mounted inside, rapidly increases as a result of miniaturization. As a result, the oscillation characteristics of the vibration element such as variable sensitivity are deteriorated.

  Also, in order to cope with the downsizing associated with the reduction in the mounting area of the mother circuit board, a new piezoelectric device package has to be designed, and no manufacturing facilities etc. are provided for the piezoelectric device using the package. Therefore, there may be cases where costs such as new capital investment are involved.

  The present invention has been devised in view of the above drawbacks, and an object thereof is to provide a piezoelectric device capable of reducing the mounting area of a mother circuit board while maintaining oscillation characteristics.

In the piezoelectric device of the present invention, at least a piezoelectric vibration element is mounted in a first recessed space opened on one main surface of the container body formed in a rectangular container body. A rectangular lid that is electrically connected to the first external connection electrode terminal formed indirectly on the other main surface of the container body and covers the opening of the first recess space is formed on the top of the side wall of the container body. In the piezoelectric device that is disposed, and that fixes the lid and the conductor layer provided on the top of the side wall, and hermetically seals the piezoelectric vibration element in the container body,
The piezoelectric device is provided with a support base on which a first external connection electrode terminal of the container body and a second external connection electrode terminal electrically connected to the lid body are attached. is there.

  Further, the support base is formed with a second concave portion having a concave cross-sectional shape, and a container body having a lid attached thereto is accommodated in the second concave portion.

  Further, a connection electrode pad for connecting to the first external connection electrode terminal and the lid is provided on the inner wall surface of the second recess of the support base, and the connection electrode electrode pad is provided on the outer bottom surface of the support base. And a second external connection electrode terminal electrically connected to each other.

The method for manufacturing a piezoelectric device according to the present invention forms a master substrate in which a plurality of rectangular support base regions are arranged adjacent to each other, and the second recesses are formed in each support base region. And a process of
A container body in which at least the piezoelectric vibration element is hermetically housed is accommodated in the second recess in each support base region of the master substrate, and first external connection electrode terminals formed on the container body are respectively provided. Electrically connecting the connection electrode pad formed in the second recess with the conductive bonding material;
Cutting along a desired outer periphery of each support substrate region of the master substrate to obtain a plurality of piezoelectric devices.

  According to the piezoelectric device of the present invention, the first external connection electrode terminal formed on the bottom surface of the container body by attaching the first external connection electrode terminal of the container body and the support base to be connected to the lid body. When the piezoelectric device is mounted on the external mother circuit board by selecting and using either the electrode terminal or the second external connection electrode terminal formed on the support base, it is necessary to reduce the mounting area of the piezoelectric device on the user side In such a case, the second external connection electrode terminal formed on the support base is used, or the first external connection electrode terminal formed on the bottom surface of the container body is used when it is necessary to reduce the height. It is possible to select one container as appropriate.

  In addition, even when the mounting area is reduced using a piezoelectric device with a support substrate, the size of the piezoelectric vibration element mounted in the piezoelectric device must be smaller than that of a piezoelectric device without a support substrate. For example, in the case of a crystal resonator or a crystal oscillator using a crystal resonator element as a piezoelectric resonator element, the CI value of the crystal resonator element mounted in the inside does not increase. It is possible to prevent the oscillation characteristics of the vibration element from deteriorating.

  Further, in the piezoelectric device of the present invention, a concave portion is formed in the support base to be provided, and the container body is accommodated in the concave portion, whereby the container body can be easily held and positioned.

  Furthermore, the piezoelectric device of the present invention is provided with a first external connection electrode terminal of the container body and a connection electrode pad for connecting to the lid body on the inner wall of the concave portion of the support base body, By providing the connection electrode terminals, it is possible to output a stable oscillation frequency without generating stray capacitance between the external connection electrode terminals. In addition, since the lid and the ground terminal of the second external connection electrode terminal can be connected in the shortest possible time, it is possible to effectively prevent unnecessary electromagnetic waves from entering the container.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view illustrating a piezoelectric device according to the present invention using a crystal resonator using a crystal resonator element as a piezoelectric resonator element which is one of the piezoelectric devices. FIG. 2 is a perspective view of a crystal resonator in which the components shown in FIG. 1 are assembled. FIG. 3 is a cross-sectional view taken along the virtual cutting line A1-A2 shown in FIG. In each drawing, parts or structures that are not necessarily required for this description are not shown. In addition, some parts or structures are exaggerated for the sake of clarity in the description of the drawings. The crystal resonator 20 shown in FIGS. 1 to 3 is generally composed of a container body 1, a crystal resonator element 2, a lid body 3, and a support base 4.

  The container body 1 is formed, for example, by laminating a plurality of insulating layers made of a ceramic material such as alumina ceramics or glass-ceramics, and a cavity portion that opens in a rectangular shape in the central region on the upper surface thereof. 5, an annular conductor layer 6 surrounding the opening of the cavity 5 is formed in the peripheral area, and a plurality of first external connection connections including an input terminal, an output terminal, and a ground terminal are provided on the lower surface of the container body 1 Electrode terminals 7 are respectively provided.

  A pair of mounting pads 8 provided on the inner bottom surface of the cavity portion 5 of the container body 1 are electrically connected to excitation electrodes of the crystal resonator element 2 to be described later on the upper surface side via a conductive adhesive 9. Input / output terminals (input terminals, output terminals) of the first external connection electrode terminals 7 on the lower surface of the container body 1 via the conductor layer 6 on the container body 1 and via conductors in the container body 1 on the lower surface side. Is electrically connected.

  On the other hand, the conductor layer 6 is electrically connected to the lid 3 described later on the upper surface side via a sealing member 10 and on the lower surface side via a via conductor formed inside the container body 1 or the like. One of the first external connection electrode terminals 7 on the lower surface is electrically connected to the ground terminal.

  Each surface of the support base 4 has a substantially rectangular shape, and is made of a resin material such as a glass cloth base epoxy resin, polycarbonate, epoxy resin, or polyimide resin, or a ceramic material such as glass-ceramic or alumina ceramic. Is formed. A recess 11 is formed in the support base 4, and the container body 1 is accommodated in the recess 11. Further, a connection electrode for connecting the lid 3 of the container body 1 and the first external connection electrode terminal 7 formed in the portion accommodated in the recess 11 to the inner wall surface in the length direction of the recess 11. A pad 12 is provided, and a plurality of second external connection electrode terminals 13 for connection to an external mother circuit board or the like are formed on the bottom surface of the support base 4.

  A support base 4 in which a part of the container body 1 is accommodated in the recess 11 and further the first external connection electrode terminal 7 and the second external connection electrode terminal 13 electrically connected to the lid 3 are formed. Is attached to the container body 1, so that either the first external connection electrode terminal 7 formed on the bottom surface of the container body 1 or the second external connection electrode terminal 13 formed on the support base 4 is replaced. When a crystal resonator is mounted on an external circuit mother circuit board and the user needs to reduce the crystal resonator mounting area, the second external connection formed on the support base 4 is used. Since it is possible to use the electrode terminal 13 or the first external connection electrode terminal 7 formed on the bottom surface of the container body 1 when it is necessary to reduce the height, crystal vibration using one container body 1 is possible. Select the usage form of the child according to the desired mounting conditions. It is possible. Further, the container body 1 can be held and positioned by the form in which the recess 11 is formed in the support base 4 and the container body 1 is accommodated in the recess 11.

  The quartz resonator element 2 is formed by attaching and forming a pair of excitation electrodes on both main surfaces of a rectangular quartz piece cut and polished at a predetermined angle from the crystal axis, and a fluctuation voltage from the outside is a pair of excitations. When applied to the crystal piece via the electrode, it vibrates at a predetermined frequency. Such a crystal resonator element 2 is electrically and mechanically connected via a conductive adhesive material 9 between the excitation electrodes attached to both main surfaces thereof and the corresponding mounting electrode pads 8 on the inner bottom surface of the cavity portion 5. Is mounted on the bottom surface of the cavity portion 5 of the container body 1.

  The conductive adhesive 9 is obtained by adding and mixing a predetermined amount of conductive particles made of Ag or the like into a resin material made of silicon resin or polyimide resin.

  Further, the lid 3 is attached to the top surface of the side wall forming the cavity 5 of the container body 1 so as to cover the opening of the cavity 5. As the lid 3, 42 alloy, Kovar, phosphor bronze, or the like is mainly used as the lid 3, and a conductor layer is formed on the lower surface of the lid 3 facing the cavity 5 via a sealing member 10 such as Au—Sn. 6 and is attached to the top surface of the side wall of the container body 1 by annularly joining the upper surface of the container body 1 along the outer periphery of the lid body 3.

  The lid 3 is for accommodating the quartz vibrating element 2 in the cavity 5 of the container body 1 and hermetically sealing it, and the first on the lower surface of the container body 1 through the conductor layer 6 described above. The external connection electrode terminal 7 is connected to the ground terminal. Similarly, the lid 3 is one of second external connection electrode terminals 13 formed on the outer lower surface of the support base 4 via connection electrode pads 12 formed on the inner wall of the support base 4. It is electrically connected to a certain ground electrode terminal.

  Therefore, when the crystal resonator is used, the lid 3 is kept at the ground potential regardless of which of the first external connection electrode terminal 7 and the second external connection electrode terminal 13 is connected to the mother circuit board. As a result, the quartz resonator element 2 is well protected from unnecessary external electrical action such as noise due to the shielding effect of the lid 3.

  In the above embodiment, as the shape of the support base 4, the shape of the concave portion 11 that only accommodates a part of the container body 1 in which a part of the first external connection electrode terminal 7 is formed is disclosed. As shown in a), one side wall portion of the support base 4 facing the first external connection electrode terminal 7 is extended to a form covering the entire bottom surface of the container body 1, and the first external connection electrode terminal 7 is formed. A corresponding connection electrode pad 12 may be formed. By using the support base in the form as disclosed in FIG. 4A, it is possible to prevent the first external connection electrode terminal 7 from being exposed to the outside of the crystal resonator, and contact accidents with other electronic components. Can be prevented. The ground electrode terminal of the first external connection electrode terminals 7 formed on the container body 1 is formed near the bottom edge of the container body 1 between other electrode terminals (input / output terminals, etc.). When the container body is configured as described above, a support base 4 having a form as shown in FIG. 4B may be used.

  In addition, as shown in FIGS. 5 and 6, the container body 1 can be held and positioned even when the side walls of the support base 4 are removed as shown in FIGS. 5 and 6. The effects of the present invention can be achieved.

Next, a manufacturing method of the above-described piezoelectric device (quartz crystal resonator) will be described with reference to FIG.
Here, FIGS. 7A to 7C are process perspective views for explaining a method of manufacturing a crystal resonator according to the present invention.

  First, as shown in FIG. 7A, a container body 1 in which a crystal resonator element 2 is accommodated and a master base 14 are prepared. The master base 14 is formed by arranging a plurality of rectangular support base regions A and abandoned regions B adjacent to each other in a matrix, and each main substrate 14 has a substrate surface A on each main surface 14. A recess 11 is formed on the surface. Each figure in FIG. 7 discloses an example in which four substrate regions A are arranged in a matrix of 2 rows × 2 columns, and a replacement region B is arranged between adjacent substrate regions A. However, the number of arrangement of this matrix is not limited to this number.

  Such a master substrate 14 is made of the same material as the support substrate 4 described above, that is, a resin material such as glass cloth base epoxy resin, polycarbonate, epoxy resin, or polyimide resin, or a ceramic material such as glass-ceramic or alumina ceramic. For example, in the case of forming with a glass cloth base epoxy resin, a glass cloth base formed by weaving glass yarn is impregnated with a liquid epoxy resin precursor and this precursor is polymerized at a high temperature. Formed by.

  Next, as shown in FIG. 7B, the container body 1 in which the crystal resonator element 2 is accommodated is attached in the recess 11 formed in each substrate region A. A crystal resonator element 2 is accommodated inside the container body 1. For example, when the container body 1 is formed of a ceramic material, a conductive paste serving as a wiring conductor is printed in a predetermined pattern on the surface of a ceramic green sheet obtained by adding and mixing an appropriate organic solvent to the ceramic material powder. The quartz vibrating element 2 is mounted on the cavity portion 5 of the container body 1 obtained by coating, forming a plurality of these layers, press-molding them, and firing them at a high temperature. At this time, the excitation electrode of the crystal resonator element 2 and the mounting pad 8 provided in the cavity portion 5 of the container body 1 are electrically and mechanically connected via the conductive bonding material 9. And it is assembled by joining the lid 3 to the upper surface of the conductor layer 6 on the upper surface of the container body. The lid 3 is manufactured by adopting a conventionally well-known metal processing method and molding a metal such as 42 alloy into a predetermined shape, and the lid 3 is fixed to the conductor layer 6 on the upper surface of the container body 1. The A plurality of first external connection electrode terminals 7 are provided on the outer lower surface of the container body 1, and these first external connection electrode terminals 7 are formed in the substrate region A of the master base 14. The contact electrode pad 12 formed in the recessed portion is brought into contact with the conductive bonding material in the solid form at a room temperature such as solder, and then the conductive bonding material is melted and liquefied by heating and then cooled. Then, the first external connection electrode terminal 7 and the connection electrode pad are mechanically and electrically connected. As a result, the container body 1 is attached and mounted in the recess 11 of each substrate region A of the master base 14.

  Next, as shown in FIG. 7C, each substrate region A is separated from the surplus region B by cutting the master base 14 along the outer periphery of each substrate region A. The master substrate 14 is cut by dicing using a dicer or the like, and the master substrate 14 is divided into individual support substrate regions A through the cutting process. As a result, a crystal resonator 20 in which a plurality of support bases 4 are attached to the container body 1 can be obtained simultaneously.

  In addition, this invention is not limited to the above-mentioned 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 configuration in which the container body is inserted and accommodated in the concave portion of the support base from the side surface in the longitudinal direction of the container body has been disclosed, but in order to further reduce the mounting area on the mother circuit board, the width of the container body Alternatively, the piezoelectric device may be inserted and accommodated from the side surface in the direction into the recess of the support base (formed with a recess and an outer shape matching the shape of the side surface in the width direction of the container body).

  In the above-described embodiment, the description has been given of the crystal resonator using the crystal resonator element as the piezoelectric resonator element, but the piezoelectric element using the piezoelectric resonator element obtained by processing lithium tantalate, lithium niobate, piezoelectric ceramic, or the like. It may be a vibrator.

  In addition, a configuration in which an electronic element such as an integrated circuit element incorporating an oscillation circuit in addition to the piezoelectric vibration element is mounted in the cavity portion 5 formed in the container body 1, or a plurality of cavity portions are formed in the container body 1. A piezoelectric oscillator in which a support base 4 is attached to a container body 1 in which a piezoelectric vibration element or an electronic element is mounted may be used. Furthermore, the present invention can also be applied to the case where another piezoelectric vibration element such as a surface acoustic wave (SAW) filter is used as the piezoelectric vibration element.

FIG. 1 is an exploded perspective view of a piezoelectric device (quartz crystal resonator) according to an embodiment of the present invention. FIG. 2 is an external perspective view in which the piezoelectric device (quartz crystal unit) disclosed in FIG. 1 is assembled. FIG. 3 is a cross-sectional view taken along the virtual cutting line A1-A2 shown in FIG. 4A and 4B are external perspective views showing another embodiment of a support base that is a component of the piezoelectric device (quartz crystal resonator) according to the present invention. FIG. 5 is an exploded perspective view of a piezoelectric device (quartz crystal resonator) according to another embodiment of the present invention. FIG. 6 is an external perspective view in which the piezoelectric device (quartz crystal unit) disclosed in FIG. 5 is assembled. 7A to 7C are process perspective views for explaining the process of the method for manufacturing a piezoelectric device (quartz crystal resonator) according to the present invention. It is sectional drawing of the conventional crystal oscillator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Container body 2 ... Piezoelectric vibration element (crystal vibration element)
DESCRIPTION OF SYMBOLS 3 ... Lid 4 ... Support base | substrate 5 ... Cavity part 6 ... Conductive layer 7 ... 1st electrode terminal for external connection 8 ... Mounted electrode pad 9 ... Conductive joining Material 10 ... Sealing member 11 ... Recess 12 ... Connection electrode pad 13 ... Second electrode terminal for external connection 14 ... Master base 15 ... Piezoelectric device (crystal oscillator)

Claims (4)

At least a piezoelectric vibration element is mounted in a first recessed space opened on one main surface of the container body formed in a rectangular container body, and the piezoelectric vibration element is directly or indirectly connected to the other of the container body. A rectangular lid that is electrically connected to the first external connection electrode terminal formed on the main surface of the container body and covers the opening of the recess space is disposed on the top of the side wall of the container body. In the piezoelectric device that adheres the body and the conductor layer provided on the top of the side wall and hermetically seals the piezoelectric vibration element in the container body,
The piezoelectric device is provided with a support base on which a first external connection electrode terminal of the container body and a second external connection electrode terminal electrically connected to the lid body are formed. Piezoelectric device.   2. The support base has a second concave portion having a concave cross-sectional shape, and the container body to which the lid is fixed is accommodated in the second concave portion. Piezoelectric device.   A connection electrode pad for connecting to the first external connection electrode terminal and the lid is provided on the inner wall surface of the second recess of the support base, and the connection electrode is provided on the outer bottom surface of the support base. 3. The piezoelectric device according to claim 1, further comprising a second external connection electrode terminal electrically connected to the pad. Forming a plurality of rectangular support base regions adjacent to each other, and forming a master substrate in which the second recesses are formed in each of the support base regions;
A container body in which at least the piezoelectric vibration element is hermetically accommodated is accommodated in a second recess in each support base region of the master substrate, and first external connection electrode terminals formed on the container body are respectively provided. Electrically connecting the connection electrode pad formed in the second concave portion of the second recess with a conductive bonding material;
A method of manufacturing a piezoelectric device comprising the step of cutting along a desired outer periphery of each support substrate region of the master substrate to obtain a plurality of piezoelectric devices.

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