JP2007274331A - Piezoelectric oscillator - Google Patents

Abstract

In a conventional piezoelectric oscillator, an integrated circuit element mounted in a piezoelectric oscillator uses an IC chip molded with a resin. A space having a volume that can be placed has to be formed, which has been considered as one of the causes that hinder the miniaturization (particularly thinning) of the piezoelectric oscillator.
A piezoelectric vibration element, one container body having the same contour shape as the piezoelectric vibration element in which the first recess is formed, a second recess, an external connection electrode terminal, and a second A piezoelectric oscillator in which an integrated circuit in which at least an oscillation circuit is formed is disposed in a recess of the piezoelectric resonator, and a piezoelectric container and a second container body having the same contour shape glass as the main product are combined and joined A piezoelectric oscillator, wherein the integrated circuit is a thin film-shaped integrated circuit body formed directly on the bottom surface of the second recess by a printing means.
[Selection] Figure 2

Description

  The present invention relates to a piezoelectric oscillator, and more particularly to a piezoelectric oscillator having a structure suitable for downsizing and thinning.

  In recent years, along with the remarkable miniaturization of devices such as mobile communication devices, further miniaturization of electronic components such as piezoelectric oscillators used in these devices is required. At present, piezoelectric oscillators having an outer size of 3.2 mm × 2.5 mm are becoming mainstream, and various piezoelectric oscillators having a size smaller than that have been developed. The piezoelectric vibration element mounted in this piezoelectric oscillator is formed on the front and back main surfaces of the piezoelectric element plate on an excitation electrode that excites the piezoelectric element member in a desired vibration mode and an insulating container that houses the piezoelectric element. The lead electrode for connecting with various electrode pads to be formed is formed. As a piezoelectric vibration element shape, a square or rectangular flat plate shape which is advantageous for downsizing has become mainstream.

  FIG. 7 shows, as an example of the prior art, an integrated circuit in which a recess is formed in the outer surface of a piezoelectric vibration element on which various electrodes are formed and is opened in a main surface facing the piezoelectric vibration element, and an oscillation circuit is built in the recess. It is sectional drawing of the width direction of the piezoelectric oscillator which airtightly sealed the vibration area | region of the piezoelectric vibration element in the form pinched | interposed with insulating container bodies, such as glass which has arrange | positioned an element. That is, in the piezoelectric oscillator 100, the container bodies 102 and 103 are respectively bonded to the top and bottom of the piezoelectric vibration element 101, and two container bodies are provided on the side surfaces in the thickness direction of the bonded container bodies 102 and 103 and the piezoelectric vibration element. An external connection electrode terminal 104 extending to the main surface is formed. Excitation electrodes 105 are formed on the front and back main surfaces of the piezoelectric vibration element 101, and the container bodies 102 and 103 are formed on both main surfaces of the piezoelectric vibration element 101 so as not to disturb the resonance vibration of the piezoelectric vibration element 101. Concave portions 106 and 107 having openings on the opposite surfaces are formed. Among these, integrated circuit elements 108 are mounted in the concave portions 107 formed in the container body 103.

  The integrated circuit element 108 has a configuration in which an IC chip in which an oscillation circuit for exciting at least the piezoelectric vibration element 101 and maintaining the vibration is incorporated is incorporated, and the IC chip is molded with resin. A plurality of container body connection electrode pads 109 formed on the main surface of the mounting body, and integrated circuit element connection electrodes formed at positions facing the respective container body connection electrodes 109 on the inner bottom surface of the recess 107 of the container body 103. The pad 110 is conductively fixed by a conductive bonding material 111 such as a metal bump or solder. Thereby, the predetermined electrode terminals of the piezoelectric vibration element 101, the integrated circuit element 108, and the external connection electrode terminal 104 are electrically connected.

The piezoelectric oscillator as described above is disclosed in the following prior art documents.
JP 2005-236562 A JP 2002-151958 A JP 2003-142748 A

  In addition, the applicant has not found any 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, in the piezoelectric oscillator having the above-described form, an IC chip molded with resin is used as an integrated circuit element mounted inside the piezoelectric oscillator. A space having a volume in which the circuit element can be placed has to be formed, which has been considered as one of the causes that hinder the miniaturization (particularly thinning) of the piezoelectric oscillator.

  The present invention has been devised in order to solve the above-mentioned problems, and the object of the present invention is to provide a conventional piezoelectric vibrator that does not use an integrated circuit element in which an IC chip is molded with a resin as in the prior art. An object of the present invention is to provide a piezoelectric oscillator that can be reduced in size and thickness.

The present invention has been made in order to solve the above-mentioned problems. An excitation electrode is provided at the approximate center of the front and back main surfaces of a flat plate-shaped piezoelectric element plate, and the piezoelectric element plate is formed from each excitation electrode. To one corner of the two opposing edges, the extraction electrode is drawn out on the same main surface as each excitation electrode, and is pulled out to one corner of the two opposing edges of the piezoelectric element plate A piezoelectric vibration element having a container body connection electrode that is electrically connected to the electrode;
The main surface opposite to one main surface of the piezoelectric vibration element is formed with a first concave portion in which the excitation electrode is positioned in the opening, and an insulating material having the same contour shape as the piezoelectric vibration element is used as the main constituent material A first container body,
A second recess having an excitation electrode located at the opening is formed on one main surface facing the other main surface of the piezoelectric vibration element, and an external connection including a ground electrode terminal on the other main surface A second container body having an insulating material having the same contour shape as that of the piezoelectric vibration element as a main structural material, in which an electrode terminal is formed and an integrated circuit in which at least an oscillation circuit is formed is disposed in the second recess. And
The first container body and the second container body are combined with the piezoelectric vibration element sandwiched therebetween, and the first space is formed so that the internal space formed by the first recess and the second recess is airtight. The container body, the second container body, and the piezoelectric vibration element are joined to each other, and a predetermined terminal of the external connection electrode terminals is formed on the electrode terminal of the integrated circuit and the piezoelectric vibration element. In a piezoelectric oscillator that is electrically connected to an electrode,
The piezoelectric oscillator according to claim 1, wherein the integrated circuit is a thin film-shaped integrated circuit body directly formed on the inner bottom surface of the second recess by a printing unit.

  Further, the main structural material of the first container body is glass, and the electrically conductive whiskers are uniformly contained in the glass structure body except for the side wall portion surrounding the first recess of the first container body. The piezoelectric oscillator described above, wherein the glass structure portion of the first container body containing whiskers and the ground electrode terminal of the external connection electrode terminals are electrically connected But there is.

  In the piezoelectric oscillator of the present invention to which the above means is applied, an integrated circuit body formed directly on the bottom surface of the recess by the printing means is used as the integrated circuit mounted and used inside the piezoelectric oscillator. It is not necessary to form a space having a volume in which circuit elements can be placed, and the piezoelectric oscillator can be downsized (particularly thinned) as the piezoelectric vibrator.

  Further, since the first container body has an EMI (Electro Magnetic Interference) action, conductive whiskers are contained, and since the conductive whiskers are at a ground potential, electromagnetic noise from outside the piezoelectric oscillator is generated. Since the influence can be effectively protected, the stray capacitance fluctuation of the container body is remarkably reduced, and therefore the possibility of the fluctuation of the frequency value of the output signal from the piezoelectric vibrator is eliminated.

  Due to such an action, the present invention has an effect of being able to provide a piezoelectric oscillator that can cope with downsizing and thinning and has a good anti-electromagnetic noise protection function.

Embodiments of a piezoelectric oscillator according to the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic exploded perspective view illustrating an embodiment of a piezoelectric oscillator according to the present invention, which is exemplified by a crystal oscillator which is an embodiment of a piezoelectric oscillator. FIG. 2 is a schematic cross-sectional view when the piezoelectric oscillator shown in FIG. 1 is assembled and then cut along a virtual cutting line A1-A2 shown in FIG. FIG. 3 is a schematic exploded perspective view illustrating another embodiment of the piezoelectric oscillator according to the present invention as a crystal oscillator which is one form of the piezoelectric oscillator. FIG. 4 is a schematic plan view of another embodiment of the piezoelectric oscillator according to the present invention, as viewed from the crystal resonator element bonding side, in a second container body constituting a crystal oscillator that is one form of the piezoelectric oscillator. FIG. 5 is a schematic exploded perspective view illustrating another embodiment of the piezoelectric oscillator according to the present invention as a crystal oscillator which is one form of the piezoelectric oscillator. FIG. 6 is a schematic cross-sectional view when the piezoelectric oscillator shown in FIG. 5 is assembled and then cut along a virtual cutting line A3-A4 shown in FIG.
In addition, the structural components which attached | subjected the same code | symbol in each figure have shown the same thing. In each of the drawings, a part of the structure is not shown, and some dimensions are exaggerated for clarity. In particular, the dimension in the thickness direction in each drawing is exaggerated.

  That is, in FIGS. 1 and 2, both main surfaces of the quartz base plate 11 having a rectangular thin plate shape using a quartz crystal which is one of piezoelectric materials as a material are substantially in the center of the quartz base plate 11. The rectangular excitation electrodes 12 are formed by vapor deposition or sputtering so that the front and back main surfaces are opposed to each other, and the front and back main excitation electrodes 12 have different crystal elements for each main surface. An extraction electrode 13 extending in the short side direction of the plate is formed. Further, at one corner of the short side of the quartz base plate 11 in which each extraction electrode 13 is extended, each extraction electrode 13 is electrically connected. A crystal resonator element 10 in which a container connection electrode 14 connected to is formed is prepared.

  Each container connection electrode 14 electrically connected to each extraction electrode 13 formed on both main surfaces is on the main surface on the side facing the second container body 22 to be described later in the crystal resonator element 10. The excitation electrode 12 and the extraction electrode 13 formed on at least a main surface facing the first container body 18 described later are conductive through-holes (not shown) that penetrate the quartz base plate 11 in the thickness direction. The electrical connection is ensured by conducting means such as). Further, the crystal element plate 11 constituting the crystal resonator element 10 is cut out from the artificial crystal at a desired cut angle and processed to have an outer shape, for example, a so-called AT cut angle crystal element plate and a thickness-shearing fundamental wave vibration mode. When a vibration in the vicinity of 300 MHz is obtained, the thickness of the quartz base plate 11 constituting the quartz resonator element 10 is processed to about 5.5 μm.

  Further, an opening is formed in the main surface opposite to one main surface (front surface) of the crystal resonator element 10, and when combined with the crystal resonator element 10 in this opening, the excitation electrode 12 and the surrounding crystal element A first container body 18 is prepared in which a first concave portion 17 having a surface on which the surface of the plate 11 is located is formed, and a glass having the same contour shape as that of the quartz crystal resonator element 10 is used as a main formation.

  Furthermore, the main surface opposite to the other main surface (back surface) of the crystal resonator element 10 has an opening, and when the crystal resonator element 10 is combined with this opening, the excitation electrode 12 and the surrounding crystal element A second recess 20 having a form in which the surface of the plate 11 is located is formed, and an external connection electrode terminal 21 including a ground electrode terminal 21a is formed on the other main surface. The second container body 22 having the same contour shape as that of the crystal resonator element 10, which is electrically connected to the container body connection electrodes 14 formed on the crystal resonator element 10. Is prepared. The electrical connection between the external connection electrode terminal 21 and the container body connection electrode 14 of the crystal resonator element 10 is made by a conductive through hole 23 formed in the second container body 22. .

  A plurality of electronic elements such as transistor elements and capacitor elements and the like are electrically connected to the inner bottom surface of the second recess 20 formed in the second container body 22 by screen printing means or inkjet printing means. An integrated circuit body 24 composed of conductive wiring and electrode pads is directly formed on the bottom surface of the second recess 20 in a thin film shape having a thickness of several to several tens of μm. Note that at least an oscillation circuit must be formed in the integrated circuit network in the integrated circuit body 24. In addition, the electrode pads formed on the integrated circuit body 24 are electrically connected to the electrode pads formed on the second container body and electrically connected to the assembled crystal resonator element 10 by wire bonding or the like. The plurality of integrated circuit connecting electrode pads are also directly formed on the bottom surface in the second recess around the integrated circuit body 24 by means similar to the integrated circuit body 24.

  Since the integrated circuit body 24 and the electrode pad for connecting the integrated circuit body in the form as described above are formed on the inner bottom surface of the second recess 20, an integrated circuit element resin-molded inside the piezoelectric oscillator as in the prior art is provided. It is not necessary to form a space having a volume that can be placed, and the piezoelectric oscillator can be downsized (particularly thinned) as the piezoelectric vibrator.

  The quartz resonator element 10 having such a configuration, the first container body 18, and the second container body 22 in which the integrated circuit body 24 and the like are formed on the inner bottom surface of the second recess are the first container body 18. 1 recess 17 opening and second recess 20 opening of the second container body 22 are directed to the crystal resonator element 10 side, with the crystal resonator element 10 sandwiched therebetween, and connected to the container body The electrode 14 and the conductive through hole 23 are combined at a position where they are electrically connected, the top surface of the side wall portion surrounding the first recess 17 in the first container body 18, and the second recess in the second container body 22 20 and the front and back main surfaces of the crystal resonator element 10 are directly bonded to each other so that the first recess 17 and the second recess are hermetically sealed, and the crystal resonator element 10 and the second The integrated circuit body 24 and various electrode terminals formed in the container body 22 are electrically connected. To form a crystal oscillator 1 was connected. The first recess 17 and the second recess 20 that are in an airtight state are filled with a vacuum or an inert gas.

  FIG. 3 discloses another type of crystal oscillator. In FIG. 1 and FIG. 2, excitation electrodes formed on the front and back main surfaces of the crystal base plate 11 toward the container body connection electrodes 14 formed at two corners that are point-symmetric with respect to the center of the crystal base plate 11. Although the case where the crystal oscillation element 10 in which the extraction electrode 13 extended to the different container body connection electrodes 14 is formed on the front and back is used is disclosed, as another form, the opposing short side edges of the crystal base plate 11 are disclosed. An extraction electrode 13 extending from the excitation electrode 12 formed on the front and back main surfaces of the quartz base plate 11 to the different container connection electrodes 14 on the front and back faces toward the container body connection electrode 14 formed on the central main surface. A crystal oscillator using the formed crystal resonator element 10 is shown. In this case, the container body connection electrode 14 formed on one main surface (front surface) of the crystal element plate 11 facing the first container body 18 is connected to the crystal element plate 11 facing the second container body 22. The container body connection electrode 14 formed on the other main surface (back surface) is electrically connected to the crystal base plate 11 through a conductive through hole 31 penetrating in the thickness direction. In addition, the formation position of the conductor through hole 23 formed in the second container body 22 is the crystal element plate facing the second container body 22 when the crystal resonator element 10 and the second container body 22 are combined. The conductive through hole 23 is in a position where it can be electrically connected to the container body connecting electrode 14 formed on the other main surface (back surface).

  Further, FIG. 4 discloses the second container body 42 constituting the crystal oscillator as an explanation of the crystal oscillator of another form. In FIG. 1, FIG. 2 and FIG. 3, as the form of the integrated circuit body 24 formed on the inner bottom surface of the second recess 20 of the second container body 22, the electrode pads of the integrated circuit body 24 and the second container body 22 Although various electrode terminals formed and a plurality of integrated circuit connection electrode pads electrically connected to the assembled crystal resonator element 10 have been disclosed, they are electrically connected by wire bonding. 4, the other end of the conductive through hole 41 having electrical connection with the external connection electrode terminal 21 at one end is formed so as to be exposed at the inner bottom surface of the second recess 44, and the exposed conductive The conductive wiring 43 and the integrated circuit body 24 that electrically connect the other end of the through-hole 41 and a predetermined electrode terminal of the integrated circuit body 24 are formed directly on the inner bottom surface of the second recess 44 by printing means. The second container body 42 of There. In the case of such a form, since an electrical connection means by wire bonding is not used, further downsizing and thinning are possible. Although the shape of the opening of the second recess 44 disclosed in the third embodiment is substantially rectangular, the shape of the second recess opening may be a circle like the second recess 20 of the first embodiment. Any of the polygons such as the third second recess 44 may be used.

  FIGS. 5 and 6 show the crystal oscillator disclosed in FIG. 1 with EMI countermeasures. That is, the crystal resonator element 50 is further connected to the ground electrode terminal 21a of the external connection electrode terminals 21 formed on the other main surface of the second container body 55 described later. A conductive through hole 52 penetrating the base plate is formed. The conduction through hole 52 is formed by a commonly used conventional technique, and the size of the opening is such that it does not affect the rigidity and vibration characteristics of the crystal resonator element 50. It is formed.

  In addition, an opening is formed in the main surface opposite to one main surface (front surface) of the crystal resonator element 50, and when the crystal resonator element 50 is combined with this opening, the excitation electrode 12 and the surrounding crystal element A first container body 53 is prepared in which the first concave portion 17 is formed so that the surface of the plate 51 is located, and the main contour is glass having the same contour shape as that of the crystal resonator element 50. Within the glass structure excluding the side wall portion surrounding the first recess 17 of the first container body 53, conductive carbon-based whiskers are uniformly distributed, and each whisker must be in close proximity to other whiskers. The first container body includes a conductive through hole 54 that is contained in a form that is electrically connected, penetrates the side wall from the glass structure containing the conductive whisker, and is electrically connected to the conductive whisker. When the 53 and the crystal resonator element 50 are combined, the exposed portion of the conduction through hole 54 on the main surface side of the crystal resonator element is formed at a position where it is electrically connected to the conductive through hole 52 of the crystal resonator element 10.

  The first container body 53, the crystal resonator element 50, and the second container body 55 in which the thin film-shaped integrated circuit body 24 and the like are formed on the inner bottom surface of the second recess 20 are the first container body. In a configuration in which the first concave portion 17 opening portion 53 and the second concave portion 20 opening portion of the second container body 55 are directed to the main surface of the quartz resonator element 50, the quartz resonator element 50 is sandwiched therebetween, The container body connection electrode 14 and the conductive through hole 23 are electrically connected to the ground terminal 21a and the glass structure portion containing the conductive whisker of the first container body 33 through the conductive through holes 23, 52 and 54. And the top surface of the side wall portion surrounding the first recess 17 in the first container body 53, the top surface of the side wall portion surrounding the second recess 20 in the second container body 55, and the front and back of the crystal resonator element 50. By directly joining to the main surface, the first A crystal oscillator 5 is formed in which the inside of the concave portion 17 and the second concave portion are hermetically sealed, and the crystal resonator element 50 and the integrated circuit body 24 formed in the second container body 55 and various electrode terminals are electrically connected. Yes.

  By forming the crystal oscillator having the above-described form, the conductive whiskers in the glass structure excluding the side wall portion surrounding the first concave portion 17 of the first container body 53 are connected to the conductive through holes 23, 52, and 54. Thus, since the conductive whiskers have a ground potential and have an EMI function because they are electrically connected to the ground electrode terminal 21a of the external connection electrode terminals 21, electromagnetic noise from the outside of the crystal oscillator 5 can be obtained. Effectively defend the influence.

  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, a crystal oscillator using quartz as an example of the material of the piezoelectric element plate constituting the piezoelectric vibration element is illustrated, but the present invention is not limited to the material disclosed in the embodiment. The present invention is effective even when lithium, lithium niobate, piezoelectric ceramics, or the like is used. In addition, when quartz is used as the material of the piezoelectric element plate, the method for forming the crystal element plate is not limited to the above-described grinding and polishing process, but is also formed by a CVD (Chemical Vapor Deposition) method. A plate may be used.

  Furthermore, in the above-described example, the main material of each container constituting the crystal oscillator is disclosed as glass. However, a form equivalent to the above-described embodiment is possible, and stress from the outside is relieved, The glass is not limited to the glass described above as long as it does not interfere with the vibration characteristics of the internal vibration element. For example, the same crystal material as the material for forming the crystal resonator element (further formed with the same cut angle) causes a fixed bonding portion during heating due to the difference in thermal expansion coefficient between the crystal resonator element and each container body. Generation of thermal stress can be suppressed, and deterioration of various characteristics of the crystal oscillator due to the stress can be prevented.

FIG. 1 is a schematic exploded perspective view illustrating an embodiment of a piezoelectric oscillator according to the present invention, which is exemplified by a crystal oscillator which is an embodiment of a piezoelectric oscillator. FIG. 2 is a schematic cross-sectional view when the piezoelectric oscillator shown in FIG. 1 is assembled and then cut along a virtual cutting line A1-A2 shown in FIG. FIG. 3 is a schematic exploded perspective view illustrating another embodiment of the piezoelectric oscillator according to the present invention as a crystal oscillator which is one form of the piezoelectric oscillator. FIG. 4 is a schematic plan view of another embodiment of the piezoelectric oscillator according to the present invention, as viewed from the crystal resonator element bonding side, in a second container body constituting a crystal oscillator that is one form of the piezoelectric oscillator. FIG. 5 is a schematic exploded perspective view illustrating another embodiment of the piezoelectric oscillator according to the present invention as a crystal oscillator which is one form of the piezoelectric oscillator. FIG. 6 is a schematic cross-sectional view when the piezoelectric oscillator shown in FIG. 5 is assembled and then cut along a virtual cutting line A3-A4 shown in FIG. FIG. 7 is a sectional view showing an embodiment of a conventional piezoelectric oscillator.

Explanation of symbols

1,5 ... Piezoelectric oscillator (crystal oscillator)
10, 30, 50 ... Piezoelectric vibration element (crystal vibration element)
11, 51 ... Piezoelectric element (crystal element)
DESCRIPTION OF SYMBOLS 12 ... Electrode for excitation 13 ... Extraction electrode 14 ... Electrode for container connection 17 ... 1st recessed part 18, 53 ... 1st container body 20 ... 2nd recessed part 21. ..External connection electrode terminals 21a: External connection electrode terminals (ground terminals)
22, 42, 55 ... second container body 23, 41, 52, 54 ... conductive through hole 24 ... integrated circuit body

Claims (2)

An excitation electrode at the approximate center of the front and back main surfaces of the flat plate-shaped piezoelectric element plate, and from each of the excitation electrodes toward one corner of the two opposite edges of the piezoelectric element plate, Each of the excitation electrodes has an extraction electrode drawn out on the same main surface, and a container body connection electrode electrically connected to the extraction electrode at one corner of two opposing edge portions of the piezoelectric element plate A piezoelectric vibration element;
A first concave portion having a shape in which the excitation electrode is located in the opening is formed on a main surface opposite to one main surface of the piezoelectric vibration element, and an insulating material having the same contour shape as the piezoelectric vibration element is mainly used. A first container body as a structural material;
A second recess having a shape in which the excitation electrode is located in the opening is formed on one main surface opposite to the other main surface of the piezoelectric vibration element, and an external including a ground electrode terminal on the other main surface A connection electrode terminal is formed, and an integrated circuit in which at least an oscillation circuit is formed is disposed in the second recess, and a second structural member made of an insulating material having the same contour shape as the piezoelectric vibration element. The container body
The first container body and the second container body are combined in a form sandwiching the piezoelectric vibration element, and the internal space formed by the first recess and the second recess is airtight. The first container body, the second container body, and the piezoelectric vibration element are joined to each other, and a predetermined terminal of the external connection electrode terminals is connected to the electrode terminal of the integrated circuit and the electrode terminal of the integrated circuit. In the piezoelectric oscillator that is electrically connected to the container body connection electrode formed on the piezoelectric vibration element,
The piezoelectric oscillator, wherein the integrated circuit is a thin film-shaped integrated circuit body directly formed on the inner bottom surface of the second recess by a printing unit.   The main structural material of the first container body is glass, and conductive whiskers are uniformly contained in the glass structure body except for the side wall portion surrounding the first recess of the first container body. 2. The piezoelectric oscillator according to claim 1, wherein the glass structure part containing the whiskers and the ground electrode terminal of the external connection electrode terminals are electrically connected.

Images