JP2007180919A - Piezoelectric device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device which can be excellently sealed while reducing its height and ensuring an area of mounting a piezoelectric resonation element, and to provide a manufacturing method thereof. <P>SOLUTION: This piezoelectric device has a piezoelectric resonation element mounted to a rectangular integrated circuit element for oscillation via a mounting pad; external terminals provided on the surface opposite to the mounting pad forming surface of the integrated circuit element for oscillation; and the device provided with post-like conductive members arranged at the external peripheral edge of the mounting pad forming surface of the integrated circuit element for oscillation, and a lid put on to hermetically seal the piezoelectric resonation element with the conductive members interposed. Further, in the piezoelectric device, the lid and the conductive members are covered with insulation resin, the post-like conductive members are used as writing control terminals for writing temperature compensation data, and further, the post-like conductive members are used as measurement terminals of the piezoelectric resonation element. Thus, the problem can be solved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

        Conventionally, a piezoelectric vibration element in which electrodes are formed on both main surfaces of a piezoelectric element plate is mounted inside a package, for example, a piezoelectric vibrator, a piezoelectric oscillator in which a piezoelectric vibrator and an oscillation circuit are mounted in the same package, or Piezoelectric devices such as a piezoelectric filter that separates a specific frequency band are often 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 miniaturization of these piezoelectric devices has been promoted along with miniaturization of electronic equipment.

        A crystal oscillator is shown as an example of such a conventional piezoelectric device. A pair of element connection electrode pads is provided in the first recess on the upper surface of the container body. 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. . Further, a structure in which an integrated circuit element 26 that outputs an oscillation signal based on the oscillation frequency of the crystal resonator element 22 is accommodated in the second recess on the lower surface of the container body is known (see, for example, Patent Document 1). ).

        In this crystal oscillator, a reference signal having a predetermined frequency is oscillated and output from an external terminal 25 provided on the lower surface of the container body 21 and functioning as a power supply voltage terminal, a ground terminal, an oscillation output terminal, and an oscillation control terminal. Such a reference signal is used as a clock signal in an electronic device such as a portable communication device.

The following documents are disclosed about the piezoelectric device including the crystal oscillator and the like as described above.
JP 2000-77943 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 prior art document information described above.

        However, according to the conventional piezoelectric device, the piezoelectric vibration element is mounted on the container body and hermetically sealed with the lid body. Therefore, in order to hermetically seal with the lid body, it is necessary to secure the wall thickness of the container body, and thus there is a disadvantage that the mounting area of the piezoelectric vibration element is reduced. In addition, since the mounting area is reduced, the piezoelectric vibration element mounted inside the piezoelectric device is also miniaturized. For example, in the case of a crystal resonator or a crystal oscillator, a crystal which is one of the piezoelectric vibration elements mounted inside is provided. The crystal impedance (CI) value of the vibration element increases rapidly due to miniaturization. Due to the influence, there is a drawback that the oscillation characteristics of the crystal resonator element such as variable sensitivity may be deteriorated.

        In recent years, a reduction in the height of the piezoelectric device has been demanded, but there has been a drawback in that there is a possibility that the strength of the member may be lost if the member such as a container is reduced in size.

        In addition, by reducing the size of the conventional piezoelectric device, it is possible to secure a region for forming a write control terminal for writing temperature compensation data and a measurement terminal for measuring the frequency characteristics of the piezoelectric vibration element. There was a drawback of becoming difficult.

        The present invention has been conceived in view of the above-described drawbacks, and an object of the present invention is to provide a piezoelectric device capable of achieving good sealing while reducing the height and securing the mounting area of the piezoelectric vibration element, and a manufacturing method thereof. It is to provide.

        The piezoelectric device of the present invention is a piezoelectric device composed of a piezoelectric vibration element and an oscillation integrated circuit element. The piezoelectric vibration element is mounted on a rectangular oscillation integrated circuit element via a mounting pad. An external terminal is provided on the surface opposite to the mounting pad forming surface of the integrated circuit element, and a post-like conductive member disposed on the outer peripheral edge of the mounting pad forming surface of the oscillation integrated circuit element; The piezoelectric vibration element is hermetically sealed so as to be sandwiched between conductive members, and is covered with a lid.

        Moreover, the piezoelectric device of the present invention is characterized in that the lid and the conductive member are covered with an insulating resin.

        The piezoelectric device according to the present invention is characterized in that a post-like conductive member is used as a write control terminal for writing temperature compensation data.

        In addition, the piezoelectric device of the present invention is characterized in that a post-like conductive member is used as a measurement terminal of a piezoelectric vibration element.

        According to another aspect of the present invention, there is provided a method for manufacturing a piezoelectric device, comprising preparing a wafer comprising a plurality of integrated circuit elements on which a mounting pad for mounting a piezoelectric vibration element and a conductive pattern for sealing are arranged in a matrix. The step A, the step B of mounting the piezoelectric vibration element, the post-like conductive member, and the lid in the region on the wafer where the integrated circuit element for oscillation is provided, and the wafer are collectively And a step C of obtaining a plurality of piezoelectric devices by cutting them individually.

        In addition, the piezoelectric device manufacturing method of the present invention is performed on the wafer in which the piezoelectric vibration element and the lid fixed so as to be sandwiched between the post-like conductive members in the step B are collectively mounted on the matrix. An insulating resin is coated on the surface.

        According to the piezoelectric device of the present invention, a piezoelectric vibration element, an oscillation integrated circuit element provided with a mounting pad for mounting the piezoelectric vibration element, a container-shaped lid body covering the piezoelectric vibration element, and And the conductive member disposed on the outer peripheral edge on the mounting pad forming surface side of the oscillation integrated circuit element, the overall structure of the piezoelectric device can be formed thinner than in the past. It becomes possible to use the device with a low profile.

        Further, according to the piezoelectric device of the present invention, by directly mounting the piezoelectric vibration element on the oscillation integrated circuit element, the excitation electrode of the piezoelectric vibration element is directly connected to the mounting pad of the oscillation integrated circuit element. Therefore, compared with the case where the oscillation integrated circuit element is mounted on the container body, the length of the wiring connecting the piezoelectric vibration element and the electronic circuit of the oscillation integrated circuit element is reduced, resulting in the wiring resistance. Thus, the generation of the capacitance can be effectively prevented, and an oscillation characteristic close to the design value can be obtained.

        In addition, according to the piezoelectric device of the present invention, the insulating resin layer is provided so as to cover the lid, thereby improving the hermetic sealing performance of the piezoelectric vibration element and having a structure capable of withstanding a drop test. Can be obtained.

        In addition, according to the piezoelectric device of the present invention, a region to be formed can be secured by using the post-like conductive member as a write control terminal for writing temperature compensation data. In addition, by forming a metal film on the surface of the insulating resin layer via a conductive member, it is possible to prevent the occurrence of writing failure due to non-contact of the writing probe.

        Further, according to the piezoelectric device of the present invention, a post-shaped conductive member can be used as a measurement terminal of the piezoelectric vibration element, so that a region to be formed can be secured and the surface of the insulating resin layer By forming the metal film via the conductive member, it is possible to prevent measurement failure due to non-contact of the measurement probe.

        Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of a schematic piezoelectric device of the present invention, and FIG. 2 is an external perspective view of a schematic piezoelectric device of the present invention. FIG. 3 is a schematic cross-sectional view of the piezoelectric device as viewed from the side direction of the present invention. The piezoelectric device shown in FIG. 3 shows an example applied to a surface-mounted crystal oscillator. In general, the piezoelectric device of the present invention includes a crystal resonator element 1 as a piezoelectric resonator element, an oscillation integrated circuit element 2, a lid 3, a conductive member 4, and an insulating resin 5.

        The oscillation integrated circuit element 2 is provided with an external terminal 6 electrically connected to the electronic circuit of the oscillation integrated circuit element 2 in the outer peripheral area of the lower surface thereof. Further, in the outer peripheral area of the upper surface, a plurality of electrode pads 7 electrically connected to the electronic circuit of the oscillation integrated circuit element 2, a plurality of electrode pads 7 electrically connected to the crystal vibration element, and the inside of these electrode pads 7 A flip-chip type integrated circuit element having a ring-shaped sealing conductor pattern 8 disposed on the upper surface and a mounting pad 9 for a crystal resonator element in the center area of the upper surface is used. Stores temperature compensation data for compensating the temperature characteristics of the temperature sensing element (thermistor) for detecting the ambient temperature state and the crystal vibration element 3 on the lower surface of the substrate made of single crystal silicon or the like, and based on the temperature compensation data. In addition, an electronic circuit such as a temperature compensation circuit that corrects the vibration characteristics of the crystal resonator element 1 according to a temperature change and an oscillation circuit that is connected to the temperature compensation circuit and generates a predetermined oscillation output is provided. Oscillation output generated in the circuit, after being outputted to the outside, for example, and thus is used as a reference signal such as a clock signal.

        The external terminals 6 (that is, the power supply voltage terminal, the ground terminal, the oscillation output terminal, and the oscillation control terminal) are connected to the external electric circuit by soldering or the like when the crystal oscillator is mounted on an external electric circuit such as a mother board (not shown). It is electrically connected to the circuit wiring.

        The conductive member 4 is connected to a plurality of electrode pads 7 provided on the oscillation integrated circuit element 2, and a write control terminal for writing temperature compensation data to the oscillation integrated circuit element 2 It is used as a measurement terminal for confirming the frequency characteristics of the crystal resonator element. For example, when used as a write control terminal, after assembling, the probe needle of the temperature compensation data writing device is applied to these write control terminals from the side or from the upper side, and the temperature characteristics of the crystal resonator element 5 are obtained. The temperature compensation data is stored in the memory of the oscillation integrated circuit element 2 by writing the corresponding temperature compensation data.

        The pair of mounting pads 9 provided on the oscillation integrated circuit element 2 is electrically connected to an excitation electrode of the crystal resonator element 1 described later via a conductive adhesive 10 on the upper surface side. The sealing conductor pattern 8 is for bonding a lid 3 to be described later to the upper surface of the oscillation integrated circuit element 2 via a sealing material 11, and the sealing conductor pattern 8 is connected to the sealing conductor pattern 8. As described above, a Ni layer and an Au layer are sequentially deposited on the surface of a base layer made of W or Mo.

        The sealing material 11 functions as a brazing material layer for joining the lid 3 to the oscillation integrated circuit element 2. The composition ratio of gold-tin is, for example, 80% gold, tin The thickness is set to 20%, and the thickness is set to, for example, 10 μm to 30 μm. It should be noted that the bonding of the oscillation integrated circuit element 2 and the lid 3 in an inert gas atmosphere or a vacuum atmosphere is performed by filling an inert gas in a space in which the crystal resonator element 1 is accommodated. This is because the electrical characteristics of the crystal resonator element 1 and the like are stabilized by maintaining a vacuum state.

        A crystal resonator element 1 is mounted on the upper surface side of the oscillation integrated circuit element 2. The crystal resonator element 1 is formed by attaching and forming a pair of excitation electrodes on both main surfaces of a crystal piece cut along a predetermined crystal axis, and a fluctuation voltage from the outside is applied to the crystal piece via the pair of excitation electrodes. When applied, it causes thickness shear vibration at a predetermined frequency. Such a crystal resonator element 1 electrically and mechanically connects the excitation electrodes attached to both main surfaces thereof and the corresponding mounting pads 9 on the upper surface of the integrated circuit element through the conductive adhesive 10. Thus, it is mounted on the upper surface side of the oscillation integrated circuit element 2.

        The conductive adhesive 10 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.

        The lid 3 is for accommodating the quartz crystal resonator element 1 in the region of the oscillation integrated circuit element 2 and hermetically sealing it, and the oscillation integration via the sealing conductor pattern 8 described above. It is electrically connected to a ground terminal which is one of the external terminals 6 formed on the lower surface of the circuit element 2. Therefore, when the crystal oscillator is used, the lid 3 is held at the ground potential, and the crystal resonator element 1 is well protected from unnecessary external electrical action such as noise due to the shielding effect of the lid 3. Has an effect.

As shown in FIG. 1, the lid 3 is formed with a concave portion by drawing so that the lid 3 can be easily disposed on the integrated circuit element 2 for oscillation. Further, as shown in FIG. 2, a lid 3 is disposed on the oscillation integrated circuit element 2, the lid 3 and the sealing material 11 are joined, and the outer peripheral surface of the lid 3 is covered with an insulating resin 5. As a result, the hermetic sealability can be further improved. This insulating resin 5 is an epoxy resin or the like and desirably has low fluidity.
In addition, since the metal film 12 is formed on the surface of the insulating resin 5 and the metal film 12 and the conductive member 4 are electrically connected, a contact area can be ensured. It is possible to prevent occurrence of measurement failure and writing failure due to contact.

        Thus, the crystal oscillator described above applies such a fluctuation voltage from the outside between the excitation electrodes of the crystal resonator element 1 to cause thickness shear vibration at a predetermined frequency according to the characteristics of the crystal resonator element 1, thereby generating such crystal vibration. Based on the resonance frequency of the child, the oscillation integrated circuit element 2 oscillates and outputs a reference signal having a predetermined frequency.

Next, the manufacturing method of the piezoelectric oscillator mentioned above is demonstrated using FIG.
Here, FIGS. 4A to 4C are schematic perspective views for explaining the manufacturing method of the present invention, and FIG. 4 shows another wafer for an oscillation integrated circuit element used in the manufacturing method of the present invention. It is the schematic perspective view seen from the main surface side (lower surface side).

(Process A)
First, as shown in FIG. 4A, a wafer oscillation integrated circuit element 2 is prepared. The oscillation integrated circuit element 2 is obtained by slicing a single crystal silicon ingot into a predetermined thickness to obtain a silicon wafer, and adopting a conventionally well-known semiconductor manufacturing technique on one main surface thereof, an electronic circuit such as an oscillation circuit or an external terminal 6. It is manufactured by forming a mounting pad 9 for mounting a piezoelectric vibration element, a sealing conductor pattern 8, and the like. A power supply voltage terminal and a ground terminal are provided on the lower surface of the oscillation integrated circuit element 2 on which the pair of mounting pads 8 and the sealing conductor pattern 8 surrounding the opening periphery are attached and formed on the oscillation integrated circuit element 2. External terminals 6 such as an oscillation output terminal and an oscillation control terminal are attached and formed.

(Process B)
Then, as shown in FIGS. 4A and 4B, each of the previous oscillation integrated circuit elements 2 on the wafer having a plurality of oscillation integrated circuit elements 2 in a matrix form vertically and horizontally is provided. The piezoelectric vibration element that is the crystal vibration element 1, the post-like conductive member 4, and the lid 3 are mounted in the provided region.
One oscillation element 1 is mounted on the oscillation integrated circuit element 2, and the excitation electrode of the oscillation element 1 and the mounting pad 9 of the oscillation integrated circuit element 2 are electrically connected via a conductive adhesive 10.・ Mechanical connection. Next, the oscillation integrated circuit element 2 and the lid 3 of the wafer are arranged so as to form a predetermined space, and the crystal resonator element 1 is accommodated and hermetically sealed. The crystal resonator element 1 is formed by attaching and forming a pair of excitation electrodes on both main surfaces of a crystal piece cut along a predetermined crystal axis, and a fluctuation voltage from the outside is applied to the crystal piece via the pair of excitation electrodes. When applied, thickness shear vibration is caused at a predetermined frequency.
The crystal resonator element 1 includes an oscillation integrated circuit element by electrically connecting a pair of excitation electrodes to a corresponding mounting pad 9 provided on each oscillation integrated circuit element 2 of a wafer via a conductive adhesive 10. 2 is implemented.

        In this way, if the crystal resonator element 1 is mounted on the oscillation integrated circuit element 2, the excitation electrode of the crystal oscillator element 1 is directly connected to the mounting pad 9 of the oscillation integrated circuit element 2, so that the crystal oscillator element The length of the wiring connecting 1 and the electronic circuit of the oscillation integrated circuit element 2 is remarkably shortened, and the generation of capacitance due to the wiring resistance can be effectively prevented. Thereby, an oscillation characteristic close to the design value can be obtained.

        The lid 3 is manufactured, for example, by processing a metal plate having a thickness of 60 μm to 100 μm made of metal such as 42 alloy, Kovar, or phosphor bronze into a predetermined shape by a conventionally known sheet metal processing. In this way, the lid 3 is formed with a recess. Such a lid 3 is used for oscillating an oscillation integrated circuit element 2 on which a crystal resonator element 1 is disposed, and a sealing conductor pattern 8 via a sealing material 11 made of gold tin (Au—Sn) or the like. The lid 3 is placed on the integrated circuit element 2 and then placed in a heating furnace maintained at a temperature of 300 ° C. to 350 ° C., for example, and the sealing material 11 is heated and melted at a high temperature. Are joined to the oscillation integrated circuit element 2. Thereafter, the integrated oscillation integrated circuit element 2 and the lid 3 are gradually cooled to room temperature.

        Further, there is a method in which the lid 3 is joined to the oscillation integrated circuit element 2 by melting the sealing material 11 using a laser beam, a halogen lamp, or the like. In this case, the technical scope of the present invention is also available. Needless to say, it is included in In this case, the halogen lamp includes a tungsten filament in a bulb and encapsulates a halogen gas. When this tungsten filament is energized and heated, it reacts with the halogen gas to produce a tungsten-halogen compound. The tungsten-halogen compound is transported to the vicinity of the filament by convection in the bulb, decomposed into tungsten and a halogen gas at a high temperature, and tungsten is precipitated in the filament. It is what happens.

        The post-like conductive member 4 is connected to a plurality of electrode pads 7 provided in the oscillation integrated circuit element 2, and is used for writing temperature compensation data into the oscillation integrated circuit element 2. It is used as a write control terminal and a measurement terminal for confirming the frequency characteristics of the crystal resonator element 1.

        Next, by covering the outer peripheral surface of the lid body 8 with the insulating resin 5, it becomes possible to further improve the hermetic sealing performance. This insulating resin 5 is an epoxy resin or the like and desirably has low fluidity. Further, by covering with the insulating resin, there is an effect that the conductive member 4 can be protected.

(Process C)
Finally, as shown in FIG. 4C, the wafer is cut along the outer periphery of the integrated circuit element 2 for oscillation. The wafer oscillating integrated circuit element 2 is cut by dicing using a dicer or the like, and the wafer oscillating integrated circuit element 2 is divided into individual integrated circuit elements through the cutting process. Thereby, a plurality of piezoelectric devices can be obtained simultaneously with high production efficiency.

        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.

        In the above-described embodiment, a surface-mount type crystal oscillator using a crystal resonator element as the piezoelectric resonator element 1 has been described as an example. Instead, a surface acoustic wave (SAW) filter or the like is used as the piezoelectric resonator element. Needless to say, the present invention can also be applied to the case of using the piezoelectric vibration element.

        In the above-described embodiment, the conductive adhesive is used when the crystal resonator element is mounted on the integrated circuit element. Instead, a conductive bonding material such as a gold bump or solder is used. You may connect using.

        In the embodiment described above, a spherical conductive member may be used instead of the post-shaped conductive member.

1 is a schematic exploded perspective view of a piezoelectric device (crystal oscillator) in an embodiment of the present invention. 1 is a schematic external perspective view of a piezoelectric device (crystal oscillator) in an embodiment of the present invention. 1 is a schematic cross-sectional view of a piezoelectric device (crystal oscillator) according to an embodiment of the present invention as viewed from a side surface direction. (A) thru | or (c) are the schematic perspective views for demonstrating the manufacturing method of the piezoelectric device (crystal oscillator) concerning one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 .... Crystal oscillation element 2 .... Oscillation integrated circuit element 3 .... Lid 4 .... Conductive member 5 .... Insulating resin 6 .... External terminal 7. ... Electrode pad 8 ... Conductive pattern for sealing 9 ... Mounting pad 10 ... Conductive adhesive 11 ... Sealing material 12 ... Metal film

Claims (6)

        In a piezoelectric device composed of a piezoelectric vibration element and an oscillation integrated circuit element, the piezoelectric vibration element is mounted on a rectangular oscillation integrated circuit element via a mounting pad, and the mounting of the oscillation integrated circuit element An external terminal is provided on the surface opposite to the pad forming surface, and a post-like conductive member disposed on the outer peripheral edge of the mounting pad forming surface of the oscillation integrated circuit element, and the conductive member A piezoelectric device comprising: a lid body that is hermetically sealed so as to be sandwiched between the piezoelectric vibration elements.         The piezoelectric device according to claim 1, wherein the lid and the conductive member are covered with an insulating resin.         2. The piezoelectric device according to claim 1, wherein the post-like conductive member is used as a write control terminal for writing temperature compensation data.         The piezoelectric device according to claim 1, wherein the post-shaped conductive member is used as a measurement terminal of the piezoelectric vibration element. Step A for preparing a wafer comprising a plurality of integrated circuit elements on which a mounting pad for mounting a piezoelectric vibration element and a sealing conductor pattern is formed arranged in a matrix.
A step B for mounting the piezoelectric vibration element, the post-like conductive member, and the lid on each of the regions where the integrated circuit elements for oscillation are provided on the wafer, and the wafer is individually divided by cutting. And C for obtaining a plurality of piezoelectric devices.         Insulating resin is collectively coated on the wafer on which the lid fixed so as to be sandwiched between the piezoelectric vibration element and the post-like conductive member in Step B is mounted in a matrix. The method for manufacturing a piezoelectric device according to claim 5.

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