JP2007124514A - Piezoelectric oscillator and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator in which the area occupied for packaging an external circuit board can be reduced, while maintaining oscillation characteristics, such as variable sensitivity. <P>SOLUTION: In a piezoelectric oscillator, a piezoelectric vibrating chip is housed in a recess formed on one principal surface of a rectangular container body, a lid body is fixed with a conductor layer provided in a sidewall apex part of the container body, the piezoelectric vibrating chip within the container body is sealed airtightly, and an integrated circuit element and an electronic element are packaged on another principal surface of the container body. In such a piezoelectric oscillator, a wall body is formed at an edge of the other principal surface of the container, and an electrode terminal for external connection is formed from one lateral side of the container body adjacent to the edge, wherein the wall body is formed, extending over the surface of the continuous wall body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric oscillator that is one of electronic components used in electronic devices such as portable communication devices and electronic computers, and a method for manufacturing the same.

  Conventionally, a piezoelectric vibrator in which a piezoelectric vibration element in which excitation electrodes are formed on both front and back main surfaces of a piezoelectric element plate are mounted in an airtight package, a piezoelectric oscillator in which a piezoelectric vibrator and an oscillation circuit are mounted in the same package, Alternatively, piezoelectric devices such as a piezoelectric filter that separates a specific frequency band are frequently used in electronic devices such as portable communication devices and electronic computers. Among them, a piezoelectric oscillator having a shape corresponding to surface mounting has been developed, and miniaturization for reducing the mounting area of the piezoelectric oscillator has been promoted along with miniaturization of electronic equipment.

  As an example of such a conventional piezoelectric oscillator, a crystal oscillator in which the main material of a piezoelectric vibration element mounted therein is quartz will be described. A pair of element connection electrode pads is provided on the bottom surface of the first recess formed on one main surface side of the container body. On the element connection electrode pad, a crystal resonator element having a pair of excitation electrodes electrically connected via a conductive adhesive on the front and back main surfaces is mounted. A seal ring is attached to the end surface of the first recess opening side wall of the container body. A metal lid is placed on the seal ring so as to cover the first recess opening, and the seal ring and the lid are joined by seam welding or the like, thereby mounting the crystal resonator element mounting space (first The inner space of the recess) is hermetically sealed. Further, the second recess formed on the other main surface side of the container body has a structure containing an integrated circuit element containing an oscillation circuit that outputs an oscillation signal based on the oscillation frequency of the crystal oscillation element. Are known.

  In addition, such a crystal oscillator includes an external power source voltage terminal, a ground terminal, an oscillation output terminal, and an oscillation control terminal provided at four corners of the opening side end surface of the side wall portion surrounding the second recess of the container body. A signal having a predetermined frequency is oscillated and output from the connection electrode terminal. Such a signal is used as a clock signal or an operation reference signal in an electronic device such as a portable communication device.

The following documents are disclosed about the crystal oscillator 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 the filing of the application other than the prior art documents specified by the prior art document information described above.

  However, as electronic devices such as portable communication devices have become multifunctional in recent years, the number of electronic components and electronic elements mounted on electronic circuit boards mounted on electronic devices has increased. Also in the mounted piezoelectric oscillator, the mounting area that can be exclusively used on the electric circuit board tends to be further reduced. If the piezoelectric oscillator is reduced in size in order to cope with these problems, the area of the portion for forming the external connection electrode terminal will be remarkably reduced, and the bonding strength between the piezoelectric oscillator and the external circuit board will be sufficient. In the worst case, the external circuit board may fall off.

  In addition, when the piezoelectric oscillator is downsized in the conventional form, the piezoelectric vibration element mounted inside the piezoelectric oscillator must also be downsized. For example, in the case of a crystal resonator or a crystal oscillator, the crystal vibration element mounted inside The crystal impedance (CI) value increases rapidly with downsizing. Due to the influence, there is a drawback that the oscillation characteristics as a crystal oscillator such as variable frequency sensitivity and start-up characteristics deteriorate.

  An object of the present invention is to provide a piezoelectric oscillator capable of reducing the mounting area of an external circuit board while maintaining various characteristics of the piezoelectric oscillator.

  The present invention has been made to solve the above-described problem, and a piezoelectric vibration element is accommodated in a concave portion formed on one main surface of a rectangular container body, and is arranged so as to cover the concave opening. By fixing the lid and the conductor layer provided on the end surface on the recess opening side of the side wall that surrounds the recess of the container body, the inner space of the recess including the piezoelectric vibration element is hermetically sealed, and the container In the piezoelectric oscillator in which an electronic element constituting at least an oscillation circuit electrically connected to the piezoelectric vibration element is mounted on the other main surface of the body, a wall body is provided at the edge of the other main surface of the container body. The electrode terminal for external connection is formed from one side surface of the container body adjacent to the edge where the wall body is formed, to the surface of the wall body continuous from the side surface. This is a piezoelectric oscillator.

  In the piezoelectric oscillator, the wall may be formed only on one of the four edges of the other main surface of the container.

  Furthermore, the electronic element formed on the other main surface of the container body is an integrated circuit element including at least an oscillation circuit, or a plurality of electronic elements including the integrated circuit element. It is also a piezoelectric oscillator.

Further, a laminated structure comprising a plurality of rectangular oscillator forming area portions arranged in a matrix and having predetermined conductive wirings on the inside and the surface thereof, and an abandoned area portion provided around the oscillator forming area portion. A concave portion for mounting the piezoelectric vibration element is formed on one main surface of each oscillator forming region portion of the master substrate having an integral structure, and an oscillator forming region portion on the other main surface of each oscillator forming region portion A wall body is formed on the surface of one edge part and the surface of the replacement area part continuous with the surface of this one edge part, and the wall is mastered from the wall body at the boundary part between the oscillator formation area part and the replacement area part. Forming a plurality of perforations to reach the substrate and connect to the external connection conductor of the master substrate, and coating the inner surface of the perforations with metal;
A step B in which a piezoelectric vibration element is mounted in each recess of the master substrate on which the wall is formed, and the space in each recess is hermetically sealed by mounting and bonding a lid in a form covering each recess opening. When,
After measuring various characteristics of each piezoelectric vibration element and making a non-defective determination, only the area where the wall of the other main surface of the oscillator forming area where the piezoelectric vibration element determined to be non-defective is mounted is not formed A step C of mounting an electronic element including an integrated circuit element electrically connected to the piezoelectric vibration element;
A step of obtaining a plurality of piezoelectric oscillators by cutting a master substrate on which a wall body is formed along a boundary between each oscillator forming region portion and abandoned region; Is the method.

  According to the piezoelectric oscillator of the present invention, the wall body is formed on the edge portion of the other main surface of the container body of the piezoelectric oscillator, and the container body adjacent to the edge portion on which the wall body is formed. Since the electrode terminal for external connection is formed from one side surface to the surface of the wall body continuous from the side surface, the structure surface having the widest area of the outer shape of the container body is defined as the surface of the external circuit board as in the prior art. Compared with the piezoelectric oscillator having the opposite surface, the area for mounting the piezoelectric oscillator dedicated to the external circuit board can be significantly reduced.

  In addition, a wall is formed only on one edge of the other main surface of the container constituting the piezoelectric oscillator, and from one side of the container adjacent to the edge where the wall is formed. Since the external connection electrode terminals are formed over the surface of the wall body continuous with this side surface, the formation area of the external connection electrode terminals of the container body can be sufficiently secured, so that the piezoelectric oscillator is extremely small. Even if it is realized, the bonding strength between the piezoelectric oscillator and the external circuit board path can be sufficiently maintained.

  According to the method for manufacturing a piezoelectric oscillator of the present invention, the external connection electrode terminal of the piezoelectric oscillator manufactured according to the present invention has a smaller area for forming the external connection electrode terminal than the conventional piezoelectric oscillator whose size has been reduced. Therefore, it is possible to perform measurement by directly contacting the electrode probe for measuring the oscillation frequency etc. from the outside during the manufacturing process, and expanding the electrode terminal for measurement. A special jig such as a socket is not required.

  Further, by arranging the integrated circuit element at a location other than the surface facing the external circuit board in the container body of the piezoelectric oscillator, the mounting area of the integrated circuit element can be increased without being limited to the area dedicated to mounting the piezoelectric oscillator on the external circuit board side. In addition, since the integrated circuit element is not surrounded by a wall body as in the prior art, it is possible to easily apply an underfill resin or the like.

  Therefore, each of the above-described actions produces an effect that it is possible to provide a piezoelectric oscillator and a method for manufacturing the piezoelectric oscillator that have an extremely small mounting area on the external circuit board, have various characteristics as an oscillator, and are easy to manufacture.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals in the respective drawings indicate the same object, and in each of the drawings, a part of the structure is not shown for clarity of explanation, and the dimensions of the illustrated part are also exaggerated. Show.
FIG. 1 is an external view showing a piezoelectric oscillator according to the present invention as an example of a crystal oscillator which is one of the piezoelectric oscillators, and (a) is a plan view seen from the integrated circuit element mounting side. ) Is a plan view seen from the external connection electrode terminal forming surface side facing the external circuit board when the crystal oscillator is mounted. FIG. 2 is a schematic cross-sectional view taken along the virtual cutting line A1-A2 shown in FIG. The crystal oscillator shown in each figure is generally composed of a container body 1, a crystal vibration element 2 as a piezoelectric vibration element, a lid body 3, and an integrated circuit element 4.

  That is, the container body 1 is formed by laminating a plurality of insulating layers made of ceramic materials such as alumina ceramics and glass-ceramics, and opens in a rectangular shape at the approximate center of one main surface thereof. A recess 5 is formed, and an annular conductor layer 6 is formed on the end surface on the recess opening side of the wall surrounding the recess 5 so as to surround the opening of the recess 5. Further, a wall body 7 is formed on the other main surface of the container body 1 at one of the four edge portions of the other main surface of the container body 1, thereby forming the wall body 7. A plurality of (three in FIG. 1) groove portions are formed from one side surface of the container body 1 adjacent to the edge of the container body 1 to the surface of the wall body continuous from the side surface. The inner surface of the groove is coated with a metal by means such as plating, and the coated metal is electrically connected to the external connection terminal of the integrated circuit element 4 through a conductive wiring formed in or on the container body 1. As a result, the external connection electrode terminals 8 that are the input terminal, output terminal, and ground terminal of the piezoelectric oscillator are formed in the groove.

  The pair of piezoelectric vibration element connecting electrode pads 10 provided on the bottom surface of the recess 5 of the container body 1 has a conductive adhesive 9 attached to an excitation electrode 12 of the crystal vibration element 2 described later on one main surface side thereof. The other main surface side is electrically connected to the integrated circuit element 4 via a conductor layer on the bottom surface of the recess 5, a via conductor inside the container body 1, or the like.

  The conductor layer 6 is fixedly connected to a conductive bonding material 11 formed on a bonding surface side edge portion of the lid 3 to be described later on one main surface side, and the container body 1 on the other main surface side. Is electrically connected to the ground terminal of the integrated circuit element 4 or the ground terminal of the external connection electrode terminals 8 via via conductors or the like inside the wall portion. The above-described external connection electrode terminal 8 is formed by using an electronic circuit wiring formed on the external circuit board and a conductive bonding material such as solder when the crystal oscillator is mounted on an external circuit board (not shown). It is designed to be connected electrically and mechanically.

  A plurality of integrated circuit element connection electrode pads 15 and electronic element connection electrode pads 16 are formed on the surface of the other main surface of the container body 1 where the wall body 7 is not formed. These various electrode pads are electrically connected to at least an integrated circuit element 4 having a built-in oscillation circuit of the crystal resonator element 2 and an electronic element 13 such as a capacitor by a conductive bonding material such as a bump or a conductive adhesive. And mechanically connected. An underfill resin 14 for protecting the electronic circuit network in the integrated circuit element 4 and the various electrode pads is applied between the surface of the integrated circuit element 4 facing the container body 1 and the other main surface of the container body 1. Has been.

  The crystal resonator element 2 mounted in the container body 1 is formed by attaching a pair of excitation electrodes 12 to both main surfaces of a rectangular flat crystal piece cut out from the artificial crystal at a predetermined cut angle. When the fluctuation voltage from the integrated circuit element 4 is applied to the crystal piece through the pair of excitation electrodes 12, the crystal vibration element 2 is excited and vibrated in a predetermined vibration mode and frequency. Wake up. The conductive adhesive 9 is obtained by adding and mixing a predetermined amount of conductive particles made of Ag or the like into a resin material made of silicon resin or polyimide resin. Further, the lid 3 is made of a metal such as 42 alloy, Kovar, phosphor bronze or the like into a flat plate shape, and a bonding material 11 such as Au-Sn is formed over the entire periphery of the edge of the container 1 bonding side. The bonding material 11 and the conductor layer 6 on the container body 1 side are firmly bonded to each other, whereby the space of the concave portion 5 in which the crystal resonator element 2 is mounted is hermetically sealed.

  In the above-described crystal oscillator, the crystal oscillator can be mounted with the surface on which the external connection electrode terminal 8 is formed as a mounting surface facing the external circuit board. Since it can be limited to the area of this mounting surface, it is possible to significantly reduce the crystal oscillator mounting area on the external circuit board. In addition, the external connection electrode terminal 8 is formed from one side surface of the container body 1 adjacent to the edge portion where the wall body 7 is formed to the surface of the wall body 7 continuous to the side surface, whereby the container Since the formation area of the external connection electrode terminal 8 of the body 1 can be sufficiently secured, the bonding strength between the piezoelectric oscillator and the external circuit board can be sufficiently maintained.

Next, a method for manufacturing the above-described crystal oscillator will be described with reference to the drawings.
(Process A)
First, as shown in FIG. 3 and FIG. 4, a predetermined conductive wiring is formed inside and on the surface, arranged in a matrix, and a plurality of rectangular oscillator forming area A, and the periphery of the oscillator forming area A A recess 5 for mounting the crystal resonator element 2 is formed on one main surface of each of the oscillator forming region portions A of the master substrate 30 having a laminated integrated structure made up of the separation region portions B provided in the The wall body 7 is formed on the surface of the one edge portion of the oscillator forming region portion A on the other main surface of the oscillator forming region portion A and the surface of the abandoned region portion B continuous with the surface of the one edge portion. A plurality of perforated portions 31 extending from the wall 7 to the master substrate 30 and connected to the external connection conductive wiring (not shown) of the master substrate 30 are formed at the boundary between the formation region portion A and the disposal region portion B. Then, the inner surface of the perforated part 31 is coated with metal. 3 is a plan view of the master substrate 30 having the four oscillator formation region portions A as viewed from the integrated circuit mounting surface side. FIG. 4 shows the master substrate 30 on which the crystal resonator element is mounted from above the crystal resonator element mounting side. FIG.

  The master substrate 30 is made of, for example, a ceramic material such as glass-ceramic or alumina ceramic, and arranged in a matrix of m columns × n rows (n and m are natural numbers greater than or equal to 2) arranged in a matrix. A concave portion 5 is formed on each of one main surface of A, and the electrode pad 10 for connecting the piezoelectric vibration element is formed on the inner bottom surface of the concave portion 5, and the concave opening side end surface of the wall portion surrounding each concave portion 5 is formed. An annular conductor layer (not shown) in a form surrounding the opening is deposited. An integrated circuit element connection electrode pad 15 and an electronic element connection electrode pad 16 are formed on each of the other main surfaces of the oscillator formation region A.

  In this embodiment, the shape of the opening of the perforated part is rectangular, but the present invention is not limited to this, and may be polygonal, circular, or elliptical. Further, the number of oscillator formation region portions A arranged is not limited to 2 columns × 2 rows disclosed in the present embodiment.

(Process B)
Next, as shown in an exploded form in FIG. 4, the piezoelectric vibration element 2 is disposed in each recess 5 of the master substrate 30 on which the wall body 7 is formed, and each recess 5 with the excitation electrode 6 of the crystal vibration element 2. The electrode pad 10 for connecting a piezoelectric vibration element formed on the bottom surface is electrically and mechanically connected via a conductive adhesive, and then the lid 3 is placed in a form covering each recess 5 opening, The bonding material formed on the edge of the container body-joining main surface of each of the lids 3 is bonded by applying heat energy, so that the spaces in the respective recesses 5 are hermetically sealed. The lid 3 is manufactured by processing a metal plate having a thickness of 60 μm to 100 μm made of a metal such as 42 alloy, Kovar, phosphor bronze or the like into a predetermined shape by conventionally known sheet metal processing.

  The series of joining steps described above is preferably performed in an inert gas atmosphere such as nitrogen gas or argon gas, or in a vacuum, whereby the inert gas is contained in the recess 5 in which the crystal resonator element 2 is accommodated. Is filled or is in a vacuum, so that the quartz resonator element 2 can be effectively prevented from being corroded or deteriorated by oxygen, moisture in the atmosphere, or the like.

(Process C)
Then, after measuring various characteristics of each piezoelectric vibration element 2 and making a non-defective product determination, as shown in FIG. 5, the other of the oscillator forming region A in which the piezoelectric vibration element 2 determined to be non-defective is mounted. The electronic element including the integrated circuit element 4 electrically connected to the piezoelectric vibration element 2 is placed and fixed only in the region where the wall 7 of the main surface is not formed. The integrated circuit element 4 is a rectangular flip-chip type integrated circuit element. In the circuit network forming portion, for example, a temperature-sensitive element (thermistor) that detects the ambient temperature state, and the temperature characteristics of the crystal vibration element 2 are used. A memory for storing temperature compensation data for compensating the temperature, a temperature compensation circuit for correcting the vibration characteristics of the crystal resonator element 2 according to a temperature change based on the temperature compensation data, and a predetermined oscillation output connected to the temperature compensation circuit The oscillation output signal generated by the oscillation circuit or the like is output to the outside of the crystal oscillator and then used as an operation reference signal for a clock signal or other electronic components.

(Process D)
Finally, as shown in FIG. 6, the master substrate 30 on which the wall body 7 is formed is cut along the boundary between each oscillator formation region A and the surplus region B, and a plurality of crystal oscillators are formed. obtain. By this cutting step, the perforated part 31 formed at the boundary between the oscillator forming area part A and the abandoned area part B is divided in the depth direction of the perforated part 31, and the oscillator forming area part A in which the wall body 7 is formed. (Container body 1) A groove-shaped external connection electrode terminal 8 extends from one side surface of the oscillator forming region A adjacent to the edge portion to the surface of the wall body 7 continuous from the side surface. The master substrate 30 is cut by, for example, cutting the master substrate 30 using a dicer or the like, whereby a plurality of crystal oscillators are obtained simultaneously. As a result, the assembly process of the crystal oscillator is greatly simplified, and it becomes possible to improve the productivity of the crystal oscillator.

  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, when individual piezoelectric oscillators are manufactured separately as in the prior art without using the manufacturing method in the present embodiment described above, the form of the external connection electrode terminal 8 is as shown in FIG. A piezoelectric oscillator having a rectangular pad shape extending from one side surface to the surface of the continuous wall 7 may be used. Further, in the above-described embodiment, the crystal oscillator using the crystal that is one of the piezoelectric materials as the material of the piezoelectric vibration element mounted in the piezoelectric oscillator is shown as an example. In addition to quartz, other piezoelectric materials such as lithium tantalate, lithium niobate, and piezoelectric ceramics may be used.

FIG. 1 shows an embodiment of a piezoelectric oscillator according to the present invention by taking a crystal oscillator as one of piezoelectric oscillators as an example, and FIG. 1A is an external plan view as seen from the integrated circuit mounting surface side. ) Is an external plan view seen from the external connection electrode terminal forming surface side. FIG. 2 is a schematic cross-sectional view taken along the virtual cutting line A1-A2 shown in FIG. FIG. 3 is a plan view of the master substrate as viewed from the integrated circuit mounting surface side for explaining the process A in the method for manufacturing a piezoelectric oscillator according to the present invention. FIG. 4 is an exploded perspective view of the master substrate as viewed from above the quartz resonator element mounting side for explaining the steps A and B in the method for manufacturing a piezoelectric oscillator according to the present invention. FIG. 5 is an external perspective view of the master substrate as viewed from above the crystal resonator element mounting side for explaining the process C in the method for manufacturing a piezoelectric oscillator according to the present invention. FIG. 6 is an external perspective view of each cut crystal oscillator viewed from above the crystal resonator element mounting side for explaining the process D in the method for manufacturing a piezoelectric oscillator according to the present invention. FIG. 7 is a schematic cross-sectional view showing another embodiment of the piezoelectric oscillator according to the present invention, taking as an example a crystal oscillator which is one of the piezoelectric oscillators.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Container body 2 ... Quartz crystal vibration element (piezoelectric vibration element)
DESCRIPTION OF SYMBOLS 3 ... Cover body 4 ... Integrated circuit element 5 ... Recessed part 6 ... Conductor layer 7 ... Wall body 8 ... Electrode terminal for external connection 9 ... Conductive adhesive material 10 ... Electrode pads for connecting piezoelectric vibrators 11... Bonding material 12... Exciting electrode 13... Electronic element 14... Underfill resin 15 ... Electrode pad for connecting integrated circuit elements 16. Element connection electrode pad 30 ... Master substrate 31 ... Perforated part A ... Oscillator formation area part B ... Disposal area part

Claims (4)

A piezoelectric body is accommodated in a concave portion formed on one main surface of a rectangular container body, and a lid body is arranged so as to cover the concave opening, and a side wall portion surrounding the concave portion of the container body. By fixing the conductor layer provided on the end surface on the recess opening side, the inner space of the recess including the piezoelectric vibration element is hermetically sealed, and the piezoelectric vibration element is provided on the other main surface of the container body. In a piezoelectric oscillator on which an electronic element constituting at least an oscillation circuit electrically connected with
A wall body is formed at the edge of the other main surface of the container body, and from one side surface of the container body adjacent to the edge portion where the wall body is formed, A piezoelectric oscillator comprising an electrode terminal for external connection formed on a surface.   2. The piezoelectric oscillator according to claim 1, wherein the wall body is formed on only one of the four edge portions of the other main surface of the container body.   The electronic element formed on the other main surface of the container body is an integrated circuit element including at least an oscillation circuit or a plurality of electronic elements including the integrated circuit element. Item 2. The piezoelectric oscillator according to Item 1. A master having a laminated integrated structure, which is arranged in a matrix and has predetermined conductive wirings formed on the inside and on the surface thereof, and includes a plurality of rectangular oscillator forming region portions and abandoned region portions provided around the oscillator forming region portions. A concave portion for mounting the piezoelectric vibration element is formed on one main surface of each of the oscillator forming region portions of the substrate, and the other surface of the oscillator forming region portion of each of the oscillator forming region portions is formed. A wall is formed on the surface of the one edge part and the surface of the replacement area part that is continuous with the surface of the one edge part, and from the wall body to the master substrate at the boundary part between the oscillator forming area part and the replacement area part of the wall body And forming a plurality of perforations to connect to the external connection conductor of the master substrate, coating the inner surface of the perforations with metal,
The piezoelectric vibration element is mounted in each of the recesses of the master substrate on which the wall body is formed, and a lid is placed and bonded so as to cover the opening of each of the recesses so that the space in each recess is hermetically sealed. Step B to stop;
After measuring various characteristics of each piezoelectric vibration element and performing a non-defective product determination, the wall of the other main surface of the oscillator forming region portion on which the piezoelectric vibration element determined to be a non-defective product is mounted is not formed. Mounting an electronic element including an integrated circuit element electrically connected to the piezoelectric vibration element only in a region; and
A step D for obtaining a plurality of piezoelectric oscillators by cutting the master substrate on which the wall body is formed along the boundary between each of the oscillator forming region portions and the abandoned region. A method for manufacturing an oscillator.

Images