JP2008060957A - Piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein, in a conventional piezoelectric oscillator, so as to electrically connect between a piezoelectric vibration element and an integrated circuit element which are mounted in a container body, it is required to route wires or lead wires in a space inside the container body on the surface of the container body, or inside the container body, however, the wires or the like have wiring resistances, and consequently, it has the adverse effect that deteriorates oscillation characteristics. <P>SOLUTION: In the piezoelectric oscillator, an electrode for connecting an insulating substrate is formed on one main face at the peripheral edge while an electrode for connecting an integrated circuit element is formed on the other main face. The electrode for connecting an insulating substrate and the electrode for connecting an integrated circuit element are electrically connected with each other by a lead wire. The piezoelectric vibration element is arranged on an element mounting pad formed in the insulating substrate. The integrated circuit element is arranged on the piezoelectric vibration element. The element mounting pad and the electrode for connecting an insulating substrate are conductively fixed. The electrode for connecting an integrated circuit element and an electrode pad for connecting a piezoelectric vibration element, are also conductively fixed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric oscillator of a form in which at least a piezoelectric vibration element and an integrated circuit element are mounted on an insulating substrate, among piezoelectric oscillators that are one of electronic components used in electronic devices such as portable communication devices. is there.

  Conventionally, in an electronic device such as a portable communication device, a piezoelectric oscillator which is one of various electronic components mounted in the electronic device is used as a reference signal or a clock signal of the electronic component mounted in the electric device or the electronic device. Used as a source of

  As an explanation of such a piezoelectric oscillator, FIG. 5 illustrates an embodiment of a conventional piezoelectric oscillator. That is, a piezoelectric vibration element made of quartz, lithium tantalate, lithium niobate or piezoelectric ceramics is mounted on the upper surface of a container body made of a ceramic material or the like so as to be held only at one end thereof, and the piezoelectric vibration element And an oscillation integrated circuit element having a built-in oscillation circuit electrically connected thereto. Furthermore, the piezoelectric oscillator has a piezoelectric vibration element hermetically sealed by placing and fixing a metal lid on the container body. (For example, see Patent Document 1).

The following prior art documents are disclosed about the piezoelectric oscillator of the above-mentioned form.
JP 2004-15441 A JP 2001-119244 A JP 2002-280835 A JP 2005-348120 A

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

However, according to the conventional piezoelectric oscillator, in order to electrically connect the piezoelectric vibration element mounted in the container body and the integrated circuit element incorporating the oscillation circuit, the container body space, the surface of the container body, or the interior of the container body In this case, the wire and the conductive wiring must be routed. However, since the wiring has a wiring resistance, the oscillation characteristic is deteriorated.
Further, according to another conventional form of the piezoelectric oscillator, there is a case where a piezoelectric vibration element and an integrated circuit element are mounted in different container bodies and the container bodies are overlapped and joined. Therefore, it is difficult to reduce the height (thinner) of a piezoelectric oscillator.
Furthermore, since the conventional piezoelectric oscillator has to route the wiring used to connect the piezoelectric vibration element, the integrated circuit element, etc. on the surface or inside of the container body, the number of processes involved in the manufacture of the container body itself, There is a risk that the manufacturing cost will increase further in time.

  Accordingly, the present invention has been devised in view of the above problems, and its purpose is to provide a piezoelectric oscillator that is easy to manufacture, can be reduced in height, and is significantly less affected by a decrease in oscillation characteristics due to wiring resistance. Is to provide.

The present invention has been made in order to solve the above-described problems. An element mounting pad for mounting a piezoelectric vibration element is provided on one main surface, and an element mounting pad is provided on the other main surface. A rectangular piezoelectric vibration region for exciting a desired frequency in a space formed by an insulating base provided with electrically connected electrode terminals for external connection and a lid, and the piezoelectric vibration region Piezoelectrically formed with an extraction electrode extending from the excitation electrode formed on the front and back main surfaces of the piezoelectric vibration region portion to the peripheral portion, the peripheral portion surrounding the portion being formed integrally with the peripheral portion having a rectangular shape. In a piezoelectric oscillator in which a vibration element and an integrated circuit element having at least a built-in oscillation circuit electrically connected to the piezoelectric vibration element are housed,
An insulating base connection electrode for mounting the piezoelectric vibration element on the insulating base is formed on one main surface facing the insulating base at the peripheral edge,
An integrated circuit element connection electrode for fixing and electrically connecting the integrated circuit element is formed on the other main surface of the peripheral edge,
The insulating substrate connection electrode and the integrated circuit element connection electrode are electrically connected by a conductive wiring formed on the surface or inside of the piezoelectric vibration element,
The piezoelectric vibration element is disposed on the element mounting pad formed on the insulating base in a form in which the predetermined element mounting pad and the insulating base connection electrode face each other.
An integrated circuit element is disposed on a piezoelectric vibration element disposed on an insulating substrate in such a manner that predetermined element connection electrodes and lead electrodes and a piezoelectric vibration element connection electrode pad formed on the integrated circuit element face each other. And
A piezoelectric oscillator characterized in that an element mounting pad and an insulating substrate connecting electrode, and an integrated circuit element connecting electrode and a piezoelectric vibration element connecting electrode pad are each conductively fixed by a conductive bonding material. is there.

  Further, the piezoelectric oscillator according to the preceding paragraph is characterized in that a concave portion is formed in a piezoelectric vibration region portion of the piezoelectric vibration element, and an excitation electrode is formed on the bottom surface of the concave portion.

  Furthermore, the piezoelectric oscillator according to paragraph (0008) is characterized in that a convex portion is formed in the piezoelectric vibration region portion of the piezoelectric vibration element, and an excitation electrode is formed on the top surface of the convex portion.

  Furthermore, the piezoelectric oscillator according to paragraph (0008) is characterized in that grooves are formed on at least two opposite sides of the outer periphery of the piezoelectric vibration region of the piezoelectric vibration element.

  According to the piezoelectric oscillator of the present invention, the integrated circuit element is connected to the integrated circuit element connection electrode formed on the peripheral portion of the piezoelectric vibration element, and the conductive wiring and the insulating substrate connection electrode formed on the piezoelectric vibration element. The integrated circuit element is directly mounted on the piezoelectric vibration element by being connected to the insulating substrate via the electrode, and the extraction electrode drawn from the excitation electrode formed in the piezoelectric vibration area of the piezoelectric vibration element is further integrated with the integrated circuit. The piezoelectric vibration element and the integrated circuit can be directly connected to a predetermined electrode pad among the piezoelectric vibration element connection electrode pads of the element, compared with the mounting form of the piezoelectric vibration element and the integrated circuit element in the conventional piezoelectric oscillator. The length of the wiring that connects the electronic circuit of the element is shortened, so that the generation of capacitance due to the wiring resistance can be effectively prevented, and good oscillation characteristics can be obtained. In addition, since there is no need to form a conductive wiring or the like for electrically connecting the piezoelectric vibration element and the integrated circuit element in the insulating substrate, it is more suitable for manufacturing than the container body constituting the conventional piezoelectric oscillator. The number of steps and the time can be further reduced.

  Further, according to the piezoelectric oscillator of the present invention, the concave portion is formed in the piezoelectric vibration region portion of the piezoelectric vibration element, and the excitation electrode is formed on the inner bottom surface of the concave portion, so that it is formed on the peripheral portion of the piezoelectric vibration element. Even if the insulating substrate connecting electrode and the integrated circuit element for oscillation are connected, the vibration energy is effectively confined by the step between the peripheral portion formed by forming the recess and the piezoelectric vibration region portion. Thus, it is possible to output a stable oscillation frequency that does not affect unnecessary stress from the peripheral edge.

  Similarly, a convex portion is formed in the piezoelectric vibration region portion of the piezoelectric vibration element, and an insulating electrode is formed on the peripheral portion of the piezoelectric vibration element by forming an excitation electrode on the top surface of the convex portion. Even if the connecting electrode and the integrated circuit element for oscillation are connected, the vibration energy can be effectively confined by the step between the peripheral edge formed by forming the convex portion and the piezoelectric vibration region portion. Thus, it is possible to output a stable oscillation frequency that does not affect unnecessary stress from the peripheral portion.

  In addition, according to the piezoelectric oscillator of the present invention, the excitation electrode is formed in the piezoelectric vibration region of the piezoelectric vibration element, and the groove is formed on the outer periphery of the excitation electrode. Even if the insulating substrate connecting electrode formed on the integrated circuit element is connected, the vibration energy can be confined in the piezoelectric vibration region inside the groove, and a stable oscillation frequency can be output. Become.

  Therefore, according to the present invention, it is possible to provide a piezoelectric oscillator that is easy to manufacture and can be reduced in height, and that is significantly less affected by a decrease in oscillation characteristics due to wiring resistance.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an exploded perspective view illustrating a piezoelectric oscillator as an example of a piezoelectric oscillator according to an embodiment of the present invention. FIG. 2 is a sectional view showing a form after the piezoelectric oscillator shown in FIG. 1 is assembled. In each figure, the same reference numerals indicate the same parts, and a part of the structure is not shown for clarity. In addition, some of the illustrated dimensions are exaggerated.
In these drawings, the piezoelectric oscillator shows one using a quartz crystal which is one of piezoelectric materials as a material of a piezoelectric vibration element mounted therein, and the piezoelectric vibration element 20 on the insulating substrate 10; An integrated circuit element 30 incorporating an oscillation circuit and a frequency adjusting circuit is mounted.

The insulating substrate 10 is formed by laminating a plurality of insulating layers made of a ceramic material such as alumina ceramics or glass-ceramic, for example. In order to connect the piezoelectric vibration element 20 to the insulating substrate 10. The element mounting pad 11 and an annular sealing conductor pattern 12 provided outside the element mounting pad 11 are provided. A plurality of external connection electrode terminals 13 including a power supply voltage terminal, an output terminal, and a ground terminal are provided on the lower main surface of the insulating substrate 10. The insulating base 10 is for mounting a piezoelectric vibration element 20 made of quartz, which is one of piezoelectric materials, on the upper main surface thereof, and the piezoelectric vibration element is provided on the upper main surface of the insulating base 10. Insulating substrate connection electrodes 22 provided on the peripheral edge 21 of 20 and the element mounting pads 11 that are electrically connected to each other are deposited.
The element mounting pad 11 connects the integrated circuit element connection electrode 22c, in which the piezoelectric vibration element connection electrode pad 31 of the integrated circuit element 30 is formed on the piezoelectric vibration element 20, and the insulating substrate connection electrode 22a. Is electrically connected to the conductive wiring 22b to be further connected through the conductive bonding material 40, and is connected to the lower main surface side of the insulating base 10 via a wiring conductor or a via-hole conductor in the insulating base 10 for external connection. The electrode terminal 13 is electrically connected to the power supply voltage terminal and the output terminal.

  The sealing conductor pattern 12 formed on the outer periphery of the insulating substrate 10 includes, for example, a nickel (Ni) layer and a gold (Au) layer sequentially on the surface of a base layer made of tungsten (W), molybdenum (Mo), etc. The insulating substrate 10 is formed to have a thickness of 10 μm to 25 μm by being attached in a ring-shaped manner, and the sealing conductor pattern 12 is formed on the lid 10 with the lid 10 described later. This is for bonding to the upper surface of the insulating substrate 10 via the sealing member 51. As described above, the sealing conductor pattern 12 is formed on the surface of the base layer made of W or Mo with the Ni layer and the Au layer. By sequentially depositing layers, the wettability of the sealing member 51 with respect to the sealing conductor pattern 12 is improved, and the hermetic reliability and productivity of the piezoelectric oscillator are improved.

  In addition, a via conductor in which one end is led out to the sealing conductor pattern 12 of the insulating base 10 and the other end is connected to the external connection electrode terminal 13 of the insulating base 10 (see FIG. (Not shown), and a substantially box-shaped lid 50 is joined via a sealing member 51 onto a sealing conductor pattern 12 deposited on the upper main surface of the insulating substrate 10. The lid 50 is electrically connected to the ground terminal among the external connection electrode terminals 13 formed on the lower surface of the insulating substrate 10 via the via conductor. As described above, since the lid 50 made of a metal material is electrically connected to the ground terminal of the external connection electrode terminal 13, the lid 50 becomes a ground potential when the piezoelectric oscillator is used. In addition, the piezoelectric shield element 20 and the oscillation integrated circuit element 30 can be well protected by an unnecessary electrical action from the outside by the electromagnetic shielding action of the lid 50. The external connection electrode terminal 13 on the mounting side main surface of the insulating substrate 10 including the ground terminal is used when the piezoelectric oscillator is mounted on an external wiring board such as a mother board, and the wiring of the external wiring board and solder or metal. It functions as an electrode terminal for electrical connection via a conductive bonding material such as a bump.

  When the insulating substrate 10 is made of alumina ceramic, the external connection electrode terminals 13 and the elements are mounted on the surface of a ceramic green sheet obtained by adding and mixing an appropriate organic solvent to a predetermined ceramic material powder. Conventionally known screens include a conductive paste to be used as a pad 11 and a conductive pattern 12 for sealing, and a conductive paste to be a via conductor in a through-hole previously punched by punching a ceramic green sheet. It is manufactured by applying by printing, laminating a plurality of these and press-molding them, followed by firing at a high temperature.

On the other hand, when the piezoelectric vibration element 20 mounted on the upper main surface of the insulating base 10 uses, for example, quartz as the material of the piezoelectric material constituting the piezoelectric vibration element 20, the crystal base plate is predetermined from an artificial crystalline lens. The piezoelectric vibration element 20 is cut to a thickness that excites a desired frequency in the thickness-sliding vibration mode. In the thickness shear vibration mode, it is necessary to reduce the thickness as the desired frequency value increases. Therefore, only the piezoelectric vibration region portion 23 is formed in a concave shape to a thickness until it vibrates at a desired frequency value by a photolithography method and etching to form the concave portion 24. A portion thicker than the concave piezoelectric vibration region so as to surround the concave portion 24 becomes the peripheral portion 21.
Excitation electrodes 25 are formed on the front and back main surfaces of the piezoelectric vibration region portion 23 in the recess 24, and an extraction electrode 26 formed by drawing the peripheral edge portion 21 from the excitation electrode 25 is formed. In addition, a number of insulating substrate connecting electrodes 22 a corresponding to the element mounting pads 11 are formed on the main surface of the peripheral portion 21 of the piezoelectric vibration element 20 facing the insulator substrate 10. A number of integrated circuit element connection electrodes 22 c corresponding to the piezoelectric vibration element connection electrode pads 31 of the integrated circuit element 30 are formed on the main surface facing the integrated circuit element 30, with the peripheral portion 21 interposed therebetween. The insulating substrate connecting electrode 22a and the integrated circuit element connecting electrode 22c, which face each other, are electrically connected by a conductive wiring 22b formed on the outer side surface of the peripheral edge portion 21.

  On one main surface of the integrated circuit element 30, when the integrated circuit element 30 is disposed on the piezoelectric vibration element 20, the integrated circuit element connection electrode 22 c and the extraction electrode 26 formed on the piezoelectric vibration element 20 are opposed to each other. The piezoelectric vibration element connection electrode pad 31 is formed at a position where the piezoelectric vibration element connection electrode pad 31 is formed. The piezoelectric vibration element connection electrode pad 31 is a predetermined part of an electronic circuit network including an oscillation circuit formed in the integrated circuit element 30. Is electrically connected to the terminal.

  The piezoelectric vibration element 20 is connected to the predetermined element mounting pad 11 and the insulating substrate on the element mounting pad 11 formed on the insulating substrate 10 with the insulating base 10, the piezoelectric vibration element 20, and the integrated circuit element 30 having the above-described form. The integrated circuit element 30 is disposed on the piezoelectric vibration element 20 disposed on the insulating substrate 10, and the predetermined integrated circuit element connection electrode 22 a and the extraction electrode 26 are integrated with the integrated circuit. The piezoelectric vibration element connection electrode pad 31 formed on the element 30 is disposed so as to oppose, the element mounting pad 11 and the insulating substrate connection electrode 22c, and the integrated circuit element connection electrode 22a and the piezoelectric element. The vibration element connecting electrode pads 31 are conductively fixed to each other by a conductive bonding material 40 such as a conductive adhesive or a metal bump. As a result, the output frequency signal of the piezoelectric vibration element 20 output from the oscillation circuit of the integrated circuit element 30 is externally connected via the predetermined element mounting pad 11 and the conductive wiring and via-hole conductor in the insulating substrate 10. The output is output from the output terminal of the electrode terminal 13 to the outside of the piezoelectric oscillator.

  In this way, the excitation electrode 25 formed in the piezoelectric vibration region portion 23 of the piezoelectric vibration element 20 and the integrated circuit element 30 (electric circuit network including an oscillation circuit incorporated therein) are directly and at a relatively short distance. Since the connection becomes possible, the length of the wiring connecting the piezoelectric vibration element 20 and the electronic circuit network in the integrated circuit element 30 is shortened as compared with the mounting form of the piezoelectric vibration element and the integrated circuit element in the conventional piezoelectric oscillator. Thus, the generation of capacitance due to the wiring resistance can be effectively prevented, and good oscillation characteristics can be obtained. A concave portion 24 is formed in the piezoelectric vibration region portion 21 of the piezoelectric vibration element 20, and an excitation electrode 27 is formed on the bottom surface of the concave portion, so that an insulating base formed on the peripheral portion 21 of the piezoelectric vibration element 20. Even if the connection electrode 22 and the oscillation integrated circuit element 30 are connected, vibration energy can be confined and a stable oscillation frequency can be output.

  The conductive adhesive 40 contains a conductive filler in a silicone resin. Examples of the conductive powder include aluminum (Al), molybdenum (Mo), tungsten (W), and platinum (Pt). , Palladium (Pd), silver (Ag), titanium (Ti), nickel (Ni), nickel iron (NiFe), or combinations thereof are used.

  The lid 50 is manufactured by adopting a conventionally well-known metal processing method and molding a metal such as 42 alloy into a substantially box shape, and a nickel (Ni) layer is formed on the opening-side flange portion joint surface of the lid 50. Further, a gold tin (Au—Sn) layer as the sealing member 51 is formed at a position corresponding to the sealing conductor pattern 12 on the upper surface of the nickel (Ni) layer. The thickness of the gold tin (Au—Sn) layer is 10 μm to 40 μm. For example, the component ratio is 80% gold and 20% tin. Moreover, such a sealing member 51 can relieve unevenness of the sealing conductor pattern 12 and prevent a decrease in hermeticity. Further, if the sealing member 51 is too thin, the function is not sufficiently exhibited.

  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, as another form of the piezoelectric vibration region, as shown in FIG. 3, a convex portion 28 is formed in the piezoelectric vibration region portion 23 of the piezoelectric vibration element 20, and the excitation electrode 25 is provided on the top surface of the convex portion 28. By being formed, even if the insulating substrate connecting electrode 22 formed on the peripheral edge 21 of the piezoelectric vibration element 20 and the oscillation integrated circuit element 30 are connected, vibration can be confined and stable. It is possible to output the oscillation frequency.

  Further, as shown in FIG. 4, the excitation electrode is formed in the piezoelectric vibration region portion 23 of the piezoelectric vibration element 20, and the groove portion 29 is formed on the outer periphery of the excitation electrode 25, whereby the piezoelectric vibration element 20. Even if the insulating substrate connecting electrode 22 and the oscillation integrated circuit element 30 formed on the peripheral portion 21 are connected to each other, the vibration can be confined and a stable oscillation frequency can be output.

FIG. 1 is an exploded perspective view of a piezoelectric oscillator according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the piezoelectric oscillator shown in FIG. 1 cut along a virtual cutting line that bisects the long side of the piezoelectric oscillator. FIG. 3 is a schematic external perspective view of a piezoelectric vibration element used in a piezoelectric oscillator according to another embodiment of the present invention. FIG. 4 is a schematic external perspective view of a piezoelectric vibration element used in a piezoelectric oscillator according to another embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing an embodiment of a conventional piezoelectric oscillator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Insulating base | substrate 11 ... Pad for element mounting 12 ... Conductive pattern for sealing 13 ... Electrode terminal for external connection 20 ... Piezoelectric vibration element (crystal vibration element)
DESCRIPTION OF SYMBOLS 21 ... Peripheral part 22a ... Insulating base | substrate connection electrode 22b ... Conductive wiring 22c ... Integrated circuit element connection electrode 23 ... Piezoelectric vibration area | region 24 ... Recessed part 25 ... Excitation Electrode 26 ... Extraction electrode 27 ... Projection 28 ... Groove 30 ... Integrated circuit element 31 ... Electrode pad for connecting piezoelectric vibration element 40 ... Conductive bonding material 50 ... Lid Body 51 ... Sealing member

Claims (4)

An element mounting pad for mounting the piezoelectric vibration element is provided on one main surface, and an external connection electrode terminal electrically connected to the element mounting pad is provided on the other main surface. A rectangular piezoelectric vibration region portion that excites a desired frequency and a peripheral portion that surrounds the piezoelectric vibration region portion and has a rectangular outer periphery shape are integrally formed in a space formed by the conductive substrate and the lid. And a piezoelectric vibration element in which an extraction electrode extending from the excitation electrode to the peripheral portion is formed on the front and back main surfaces of the piezoelectric vibration region part, and an oscillation circuit electrically connected to the piezoelectric vibration element In a piezoelectric oscillator in which at least an integrated circuit element having a built-in capacitor is housed and mounted, an insulating substrate connection for mounting on the insulating substrate is provided on one main surface of the peripheral portion facing the insulating substrate. Forming electrode An integrated circuit element connection electrode for fixing and electrically connecting the integrated circuit element is formed on the other main surface of the peripheral edge,
The insulating base connection electrode and the integrated circuit element connection electrode are electrically connected by a conductive wiring formed on the surface or inside of the piezoelectric vibration element,
The piezoelectric vibration element is disposed on an element mounting pad formed on the insulating base in a form in which the predetermined element mounting pad and the insulating base connection electrode are opposed to each other.
The integrated circuit element faces a predetermined element connecting electrode and the extraction electrode on the piezoelectric vibration element disposed on the insulating base, and a piezoelectric vibration element connecting electrode pad formed on the integrated circuit element. Arranged in a form,
The element mounting pad and the insulating substrate connection electrode, and the integrated circuit element connection electrode and the piezoelectric vibration element connection electrode pad are each conductively fixed by a conductive bonding material. Piezoelectric oscillator.  The piezoelectric oscillator according to claim 1, wherein a concave portion is formed in a piezoelectric vibration region portion of the piezoelectric vibration element, and an excitation electrode is formed on a bottom surface of the concave portion.  The piezoelectric oscillator according to claim 1, wherein a convex portion is formed in a piezoelectric vibration region portion of the piezoelectric vibration element, and an excitation electrode is formed on a top surface of the convex portion.  The piezoelectric oscillator according to claim 1, wherein grooves are formed on at least two opposing sides of the outer periphery of the piezoelectric vibration region of the piezoelectric vibration element.

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