JP2007060593A - Piezoelectric device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device capable of performing sealing with excellent airtightness by ensuring a piezoelectric vibrating element mount area inside the device. <P>SOLUTION: In the piezoelectric device, a step difference part 11 convex toward one principal side of a wiring board is provided to a side face of the wiring board 1, a joining member 9 is formed to a side face of the step difference part 11, an inner face of a side wall of a cover 8 and the joining member are joined, and an internal space formed by the cover and the one principal side of the wiring board is airtightly sealed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  Conventionally, a piezoelectric device such as a piezoelectric vibrator, a piezoelectric oscillator, or a surface acoustic wave filter has been used as one of electronic components constituting an electronic device such as a portable communication device or an electronic computer.

  A piezoelectric vibrator will be described as an example of such a conventional piezoelectric device. It is fixed in a state of surrounding a space on one main surface of the wiring substrate including a wiring substrate having a laminated structure in which conductive wiring is formed and a piezoelectric vibration element supported on one main surface of the wiring substrate. The wiring board body comprises a flat wiring board having a plurality of through holes, and a metal plating wall formed in an annular shape along the peripheral edge of one main surface of the wiring board. An internal electrode that is arranged on one main surface of the wiring board and supports the piezoelectric vibration element so as to block each upper opening of the plurality of through holes located inside the metal plating wall, and the other of the wiring board The main surface has metal-plated external connection electrodes arranged so as to block the lower openings of the plurality of through holes. The metal lid is fixed to the upper surface of the metal-plated wall, and the bottom surface of the hem is fixed to the bottom surface. From the brazing material frame to be formed and the hem Consists of a Chi rose Gyakuwan portion has a structure formed by joining and this brazing material frame and the metal plating wall.

  The piezoelectric device (piezoelectric vibrator) as described above is disclosed in the following technical information literature.

JP 2003-87071 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 prior art document information described above.

  However, in the case of a conventional piezoelectric device using a hat-shaped (conforms to the above-mentioned inverted saddle shape) metal lid, the periphery of the opening of the metal lid is folded back outwardly (the above-described hem portion) And the wiring board has a form for securing the region for forming the bonding material at the edge of the main surface of the bonding side with the metal lid and bonding the folding of the metal lid and the bonding material. It is necessary to secure a ring-shaped region for bonding around the piezoelectric device. In order to secure this region, there is a drawback that the area where the piezoelectric vibration element can be mounted is reduced. In addition, when the mounting area of the piezoelectric vibration element is secured, the size of the piezoelectric device body may be increased.

  Further, since the mounting area of the piezoelectric vibration element is reduced, it is necessary to reduce the size of the piezoelectric vibration element that can be mounted thereon. When the piezoelectric vibration element is reduced in size, the oscillation characteristic and crystal impedance (CI) value of the piezoelectric vibration element are increased, and the variable sensitivity and the starting characteristic are deteriorated.

  The present invention has been devised in view of the above-described drawbacks, and an object of the present invention is to provide a piezoelectric device capable of good airtight sealing while securing a mounting area of the piezoelectric vibration element inside the device. .

The piezoelectric device according to the present invention includes a wiring board and a wiring board in a form in which at least a piezoelectric vibration element is disposed on one main surface of the wiring board and one main surface of the wiring board on which the piezoelectric vibration element is disposed is covered. In a piezoelectric device comprising a box-shaped lid fixed to
A side surface of the wiring board is provided with a stepped portion projecting toward one main surface of the wiring board, a bonding material is formed on the side surface of the stepped portion, and an inner surface of the side wall portion of the lid and the bonding material are provided. The piezoelectric device is characterized in that an inner space formed by joining and formed by one main surface of the lid and the wiring board is hermetically sealed.

  The piezoelectric device as described in the above item, wherein a groove portion having a depth component from the surface of the one main surface to the thickness direction of the wiring substrate is provided at the edge portion of the one main surface of the wiring substrate. It is also a device.

  Further, the piezoelectric device described above is characterized in that a resin layer is provided on the surface of the lid, the wiring board, and the bonding portion appearing on the outer surface of the device.

In the piezoelectric device manufacturing method according to the present invention, one of the wiring board regions is arranged on each outer peripheral edge of the wiring board region of the master board in which a plurality of wiring board regions arranged in a matrix are integrally formed. A step A in which a convex step portion is provided on the main surface of the substrate, a bonding material is formed on a side surface of each step portion, and at least a piezoelectric vibration element is mounted on one main surface of each wiring board region of the master substrate. When,
A box-like lid for hermetically sealing the space in which the piezoelectric vibration element is mounted is disposed on one main surface of each wiring board region of the master board, and the inner surface of the side wall of the lid Step B for bonding the bonding material;
Step C for simultaneously obtaining a plurality of piezoelectric devices by collectively cutting and separating along the outer periphery of each wiring board region of the master substrate;
A method for manufacturing a piezoelectric device comprising:

  Further, the outer peripheral edge of one main surface of each wiring board region is provided with a groove having a depth component in the thickness direction of the wiring board region from the surface of one main surface. It is also a method for manufacturing a piezoelectric device.

  The method for manufacturing a piezoelectric device according to the above, further comprising a step of providing a resin layer on the surface of the lid, the wiring board, and the joint portion appearing on the outer surface of each piezoelectric device after cutting the master substrate. is there.

  According to the piezoelectric device of the present invention, the bonding material is formed in an annular shape on the side surface of the step portion formed on the side surface of the wiring board, and the inner surface of the side wall portion of the box-shaped lid is bonded to the bonding material. Therefore, the lid body does not need to be folded back for joining around the opening as in the conventional case, and the wiring board is joined to the edge on the joint-side main surface with the lid body. Since it is not necessary to secure a region for forming the material, it is possible to sufficiently secure the mounting area of the piezoelectric vibration element on the main surface of the wiring board. In addition, since the step portion is formed, it is possible to position the wiring board so that the wiring board is not inserted deeper than necessary by the step and the mounting space of the piezoelectric vibration element is not significantly reduced, and the bonding material is provided inside the device. It is possible to prevent the piezoelectric vibration element from being scattered and adhered.

  Further, according to the piezoelectric device of the present invention, a groove portion having a depth component from the one main surface to the thickness direction of the wiring substrate is provided on the edge portion of the one main surface of the wiring substrate. Even if the bonding material formed on the outer periphery of the side surface of the wiring board flows into the main surface of the wiring board at the time of bonding, the inflow is prevented at the groove portion, and the piezoelectric vibration element or the like caused by the flowing bonding material is adversely affected. Disappears.

  Furthermore, according to the piezoelectric device of the present invention, since the resin layer is provided on the surface of the lid, the wiring board, and the bonding portion appearing on the outer surface of the device, the bonding strength particularly at the four corners of the device is increased. As a result, the airtightness can be further improved. Furthermore, the drop strength can be improved by providing the resin layer.

  Furthermore, according to the piezoelectric device manufacturing method of the present invention, the bonding material is formed by bonding the inner surface of the side wall portion of the box-shaped lid and the bonding material formed on the side surface of the stepped portion formed on the outer peripheral portion of each wiring board region. Does not enter or scatter in the piezoelectric vibration element mounting portion of each wiring board region, and the bonding material does not adhere to the piezoelectric vibration element. Therefore, it is possible to provide a piezoelectric device with stable oscillation characteristics. In addition, since a plurality of piezoelectric devices can be collectively produced using the master substrate, device productivity can be improved.

  In addition, since a step portion is provided along the outer periphery of each wiring board region, and the lid can be positioned and positioned by this step portion, the lid body can be arranged in each wiring board region in a fixed form. Become. Furthermore, it is not necessary to provide a mechanism for positioning and positioning the lid on the apparatus side.

  Also, by providing a groove near the outer periphery of each wiring board area of the master board, even if the bonding material flows into the wiring board area, the groove prevents the inflow of the bonding material. There will be no adverse effects. Furthermore, by providing a resin layer on the surface of the lid, wiring board, and joint that appears on the outer surface of the device, the joint strength at the four corners of each device will increase, making it possible to further improve the airtightness. Further, by providing the resin layer, it is possible to improve the impact resistance strength when dropped.

  Therefore, each of the above-described actions produces an effect that it is possible to provide a piezoelectric device that is small and has various characteristics, and a manufacturing method that has good productivity of such a piezoelectric device.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol in each figure shall show the same object. In each of the drawings, a part of the structure is not shown, and some dimensions are exaggerated for the sake of clarity.

  FIG. 1 is an exploded perspective view illustrating an example of a crystal resonator which is one of the piezoelectric devices of the piezoelectric device according to the present invention, and FIG. 2 is a cross-sectional view when the crystal resonator shown in FIG. 1 is assembled. . The crystal resonator shown in the figure is generally composed of a wiring substrate 1, a crystal resonator element 5 as a piezoelectric resonator element, and a lid 8.

  The wiring substrate 1 is formed by laminating layers made of a ceramic material such as glass-ceramic and alumina ceramic, for example, and a pair of element connection electrode pads on one main surface (for convenience). 2 is provided, and an electrode terminal 3 for external connection such as an input terminal, an output terminal, and a ground terminal is provided on the other main surface (for the sake of convenience).

  A pair of element connection electrode pads 2 provided on one main surface of the wiring substrate 1 are electrically conductive adhesives to excitation electrodes 6 of a crystal resonator element 5 described later on the upper surface side of the element connection electrode pads 2. Of the external connection electrode terminals 3 formed on the other main surface of the wiring board 1 via the conductor pattern on the wiring board 1 and via conductors inside the wiring board on the lower surface side. Are electrically connected to the input / output terminals (input terminal, output terminal). These external connection electrode terminals 3 are electrically connected to the external electric circuit network such as a mother board through a circuit material of the external electric circuit network and a conductive bonding material such as solder when the crystal unit is mounted on the external electric circuit network. Connected.

  Further, a stepped portion 11 that is convex toward one main surface of the wiring substrate 1 is provided on the side surface of the wiring substrate 1, and the wiring substrate 1 is provided on a side surface of the stepped portion 11 on the one main surface side of the wiring substrate 1. One main body, a bonding material 9 to be described later, and a conductor layer 4 for fixing are provided. The conductor layer 4 has a structure in which a Ni layer and an Au layer are sequentially deposited on the surface of a base layer made of W or Mo.

  A bonding material 9 is formed on the surface of the conductor layer 4, and the bonding material 9 functions as a brazing material for bonding the lid 8 to the wiring substrate 1. An alloy of gold and tin is used as the material of the bonding material 9. The composition ratio of gold and tin is set to, for example, 80% gold and 20% tin, and the thickness is set to approximately 10 μm to 40 μm.

  A crystal resonator element 5 is mounted on the element connection electrode pad 2 formed on one main surface of the wiring board 1 described above. The quartz resonator element 5 is formed by attaching and forming a pair of excitation electrodes 6 on both main surfaces of a quartz base plate that is cut from an artificial crystalline lens with a predetermined crystal axis and is subjected to external shape processing. When applied to the quartz base plate via the excitation electrode 6, vibrations of various vibration modes are generated at a predetermined frequency. The quartz resonator element 5 is electrically and mechanically connected to the excitation electrode 6 attached to both main surfaces thereof and the element connecting electrode pad 2 on one main surface of the wiring board 1 through a conductive adhesive. It is mounted on one main surface of the wiring board 1 by being connected to.

  The lid body 8 has an outline like a box having a generally open shape, and the shape of the opening is the same as the outer peripheral shape of the side surface of the step portion 11 formed on the wiring board 1 (including the bonding material 9). The wiring board 1 is fitted into the opening of the lid 8 in such a manner that one main surface side surface of the step portion 11 formed on the side surface of the wiring board 1 is fitted to the inner surface of the lid body 8. The crystal resonator element 5 mounted on one main surface of the wiring board 1 is hermetically sealed by closely bonding and bonding the bonding material 9 formed around the side surface of the lid 8 and the inner surface of the side wall of the lid 8. It has stopped. By fitting the opening portion of the lid body 8 to the stepped portion 11, the positioning of the lid body 8 can be facilitated when the lid body 8 is disposed on the wiring board 1.

  Further, the lid 8 is the GND of the electrode layers for external connection formed on the other main surface of the wiring board 1 through the conductor layer 4 and the via conductors and conductive wirings formed in the wiring board 1 described above. Electrically connected to the terminal. Therefore, when the crystal unit is used, the lid 8 is held at the ground potential, and the quartz resonator element 5 is well protected from unnecessary external electrical action such as noise due to the shielding effect of the lid 8. Is done.

  As another embodiment of the crystal unit of the present embodiment, as shown in FIG. 3, the wiring board 1 is connected to each edge portion on one main surface side of the wiring board 1 from the surface of the one main surface. If the groove portion 12 having a depth component in the thickness direction 1 is formed, even if the bonding material 9 flows into one main surface of the wiring board 1 when the lid body 8 is bonded, it flows in. Since the bonding material can be further prevented from flowing into the inside of the wiring substrate 1 by the groove portion 12, the bonding material does not adhere to the crystal resonator element 5, and stable vibration characteristics can be obtained.

  Further, as shown in FIG. 4, the opening side wall end portion of the lid body 8 is arranged at the step portion 11, and the bonding material 9 formed on the lid body 8 and the step portion 11 is joined and also appears on the outer surface of the device. A resin layer 14 is provided on the surface of the lid 8, the wiring substrate 1, and the joint. By providing this resin layer 14, the airtightness can be further improved. In particular, since there may be a slight gap between the lid 8 and the bonding material 9 at the four corners of the device, the provision of the resin layer 14 is effective for further improving the airtightness. The resin layer 14 is formed of an epoxy resin and preferably has low fluidity.

  Further, as shown in FIG. 5, among the plurality of layers constituting the wiring board 1, an intermediate layer constituting one main surface side surface of each step portion except for one main surface side outermost layer of the wiring board 1. Even when the conductor layer 4 and the bonding material 9 are formed only on the side surfaces of the wiring board 1, the bonding material 9 is prevented from being scattered and attached to the crystal resonator element 5 disposed on the outermost layer on one main surface side of the wiring board 1. Is possible.

  Thus, the above-described crystal resonator has an externally varying voltage between the front and back excitation electrodes of the crystal resonator element 5 via the input / output terminals of the external connection electrode terminals 2 provided on the other main surface of the wiring board 1. By applying and causing vibration at a predetermined frequency according to the characteristics of the crystal resonator element 5, it functions as a crystal resonator. Based on the resonance frequency of the crystal resonator, a reference signal having a predetermined frequency is generated by an external oscillation circuit. Oscillates / outputs. Such a reference signal is used as a clock signal in an electronic device such as a portable communication device.

Next, with reference to FIGS. 6 to 8, each step of the above-described method for manufacturing a crystal resonator will be described.
(Process A)
First, as shown in FIG. 5, a master substrate 10 having a plurality of wiring board regions arranged in a matrix is prepared, and for element connection formed on one main surface of each wiring board region of the master substrate 10. A crystal resonator element 5 is mounted on the electrode pad 2.

  The master substrate 10 includes, for example, two rectangular flat substrates made of a ceramic material such as glass-ceramic and alumina ceramic, and has m columns × n rows (m and n are natural numbers of 2 or more). In this matrix form, a plurality of wiring board regions having a rectangular outer peripheral shape are set. On each wiring board area, a flat board having a similar outer peripheral shape to each wiring board area and having a smaller outer peripheral dimension than the outer circumference of the wiring board area is laminated, and a step 11 is formed at the outer peripheral edge of each wiring board area. To do. Each wiring board region set in a matrix form has a pair of element connecting electrode pads 2 on one main surface and one main surface side of a step portion 11 surrounding each wiring board region. A conductor layer 4 is deposited and formed on the side surface. In addition, external connection electrode terminals 3 serving as input / output terminals and ground terminals are formed on the other main surface of each wiring board region.

  Each layer constituting such a master substrate 10 includes, for example, an element connection electrode pad 2 or the like on the surface of a ceramic green sheet obtained by adding and mixing a suitable organic solvent to a ceramic material powder made of alumina ceramic or the like. Produced by printing / coating a predetermined pattern of conductor paste, which is a conductor pattern, etc., provided on the external connection electrode terminal 3 and each wiring board region, and then laminating the required number of sheets, press-molding, and firing at a high temperature Is done.

  Further, the conductor layer 4 formed on one main surface side surface of the step portion 11 formed at the outer peripheral edge of each wiring board region is formed by sequentially depositing a Ni layer and an Au layer on the surface of W or Mo. The bonding material 9 made of gold tin (Au—Sn) is deposited on the surface of the conductor layer 4. This bonding material 9 functions as a brazing material for bonding the lid body 8 to the wiring board 1. The composition ratio of gold tin is approximately 80% gold and 20% tin, and the thickness is approximately. It is formed with a thickness of 10 μm to 30 μm.

  In addition, the crystal resonator element 5 is mounted on each wiring board region of the master substrate 10 formed in this way, and the element is connected to the excitation electrode 6 of the crystal resonator element 5 and one main surface in each wiring substrate region. The electrode pad 2 is electrically and mechanically connected via the conductive adhesive 7.

  Furthermore, as another embodiment of the present invention, in the vicinity of the outer periphery of one main surface of each wiring board region constituting the master substrate 10, the wiring board region is formed in a surrounding form from one main surface of each wiring substrate region. By providing the groove portion 12 having a depth component in the thickness direction, even when the bonding material 9 flows out when the lid body 8 and the bonding material 9 are bonded in a process described later, the quartz crystal is blocked by the groove 12. Since the bonding material 9 does not adhere to the vibration element 5, stable oscillation characteristics can be obtained.

(Process B)
Next, as shown in FIG. 6, the outer peripheral shape is substantially box-shaped and the shape of the opening is one main surface side side outer peripheral shape (including the bonding material 9) of the step portion 11 formed in each wiring board region. The same lid 8 is arranged on one main surface of each wiring board region of the master substrate 10 so that the opening of the lid 8 fits into the stepped portion 11, and is joined to the inner surface of the side wall of the lid 8. The material 9 is joined, and the crystal resonator element 5 mounted on one main surface of each wiring board region is hermetically sealed.

  The lid 8 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, or phosphor bronze into a predetermined shape by a conventionally known sheet metal processing. The lid 8 is formed by pressing a plate-like metal into a box shape, and a nickel (Ni) layer is formed on the inner surface of the lid 8.

  The lid body 8 having such a configuration is placed on the step portion 11 formed on the outer peripheral edge portion of each wiring board region of the master substrate 10 so as to cover the crystal resonator element 5 on each corresponding wiring board region. Thereafter, the lid 8 is placed in a heating furnace maintained at a temperature of 300 ° C. to 350 ° C., and the bonding body 9 formed on the step portion 11 is heated and melted at a high temperature so that the lid body 8 is stepped in each wiring board region. It is joined to the part 11. Thereafter, the integrated master substrate 10 and the plurality of lids 8 are gradually cooled to room temperature. 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 an inert gas is contained in the internal space in which the crystal resonator element 5 is accommodated. Since the liquid crystal is filled or evacuated, it is possible to effectively prevent the quartz resonator element 5 from being corroded or deteriorated by oxygen, moisture in the atmosphere, or the like.

(Process C)
Finally, as shown in FIG. 7, in step B, the master substrate 10 in which the lid 8 is bonded to each wiring board region is collectively cut along the outer periphery of each wiring board region, and individual crystal resonators are separated. obtain. The master substrate 10 is cut by, for example, collectively cutting the master substrate 10 from the master substrate side using a dicer or the like, whereby a plurality of crystal resonators are obtained simultaneously. As shown in FIG. 4, after the master substrate is cut and individual crystal resonators are formed, the lid 8 and the wiring substrate 1 appearing on the outer surface of the crystal resonator and the surface of the bonding portion are made of epoxy resin. The resin layer 14 is applied by a dispenser and cured by applying heat. This can increase the joint strength and further improve the airtightness.

  In addition, in this case, since the master substrate 10 itself functions as a carrier when assembling the crystal resonator, it is complicated to assemble the crystal resonator by individually holding the separated wiring substrates on the carrier. No work is required, which greatly simplifies the process of assembling the crystal unit, which can improve the productivity of the crystal unit.

  In the following, a form of a crystal oscillator which is one of piezoelectric devices will be described as another embodiment according to the present invention. The crystal oscillator shown in FIGS. 9 to 13 is generally composed of a wiring board 51, a crystal vibration element 56 as a piezoelectric vibration element, an integrated circuit element 55 incorporating an oscillation circuit, and a lid 58. . In FIG. 9, a wiring substrate 51 is formed by laminating ceramic green sheets made of a ceramic material such as glass-ceramic or alumina ceramic, and a pair of element connecting electrode pads is provided on one main surface side. 52, and a power supply voltage terminal, a ground terminal, an oscillation output terminal, and an external connection electrode terminal 53 for an oscillation control terminal are provided on the other main surface side. A concave portion 60 is formed at the approximate center of one main surface of the wiring substrate 51, and the concave portion 60 is disposed on one main surface side of the plurality of ceramic green sheets constituting the wiring substrate 51. It is formed by drilling a rectangular through hole in the center of the ceramic green sheet.

  A pair of element connection electrode pads 52 provided on one main surface side of the wiring board 51 are electrically connected to excitation electrodes of a crystal resonator element 56 described later on the upper surface side thereof via a conductive adhesive 57. The oscillation output terminal of the external connection electrode terminal 53 formed on the other main surface of the wiring board 51 via a conductor pattern on one main surface of the wiring board 51 or a via conductor inside the wiring board on the lower surface side. Is electrically connected.

  Further, a stepped portion 61 that protrudes toward one main surface of the wiring substrate 51 is provided on the side surface of the wiring substrate 51, and the wiring portion 51 on the side surface on the one main surface side of the stepped portion 61 has a wiring A main body of the substrate 51 and a conductor layer 54 for fixing to a bonding material 59 described later are provided. The conductor layer 54 has a configuration in which a Ni layer and an Au layer are sequentially deposited on the surface of a base layer made of W or Mo.

  The conductor layer 54 is electrically connected to a cover body 58 to be described later on the exposed surface side through a bonding material 59, and the other side of the wiring substrate 51 on the non-exposed surface side via a via conductor or the like inside the wiring substrate 51. Are electrically connected to the ground (GND) terminal of the external back connection electrode terminals 53 formed on the main surface. The conductor layer 54 is for bonding a lid body 58, which will be described later, to the side surface of the wiring board 51 via a bonding material 59. The conductor layer 54 is formed on the surface of a base layer made of W or Mo with a Ni layer and an Au layer. The layers are sequentially deposited.

  The bonding material 59 functions as a brazing material for bonding the lid body 58 to the wiring board 51. In the second embodiment, gold tin is used as the material of the bonding material 59. The composition ratio of gold tin is set to, for example, 80% gold and 20% tin, and the thickness thereof is, for example, 10 μm to 30 μm.

  A crystal resonator element 56 is mounted on the element connection electrode pad 52 formed on one main surface of the wiring substrate 51 described above. The quartz resonator element 56 is formed by attaching and forming a pair of excitation electrodes on both main surfaces of a quartz base plate that is cut from an artificial crystalline lens at a predetermined crystal axis angle and is subjected to external shape processing. When applied to the quartz base plate via the excitation electrode, vibrations of various vibration modes are generated at a predetermined frequency. The quartz-crystal vibrating element 56 is electrically and mechanically connected to an excitation electrode attached to both main surfaces thereof and an element connecting electrode pad 52 on one main surface of the wiring board 51 through a conductive adhesive 57. Is mounted on one main surface of the wiring substrate 51.

  An integrated circuit element 55 including an electronic circuit network including an oscillation circuit electrically connected to the crystal resonator element 56 is mounted in the recess 60 of the wiring board 51 described above. As the integrated circuit element 55, for example, a flip chip type integrated circuit element 55 having a plurality of connection terminals on the mounting side surface with the wiring substrate 51 is used. , A temperature sensing element (thermistor) for detecting the ambient temperature state, temperature compensation data for compensating the frequency temperature characteristic of the crystal vibrating element 56 are stored, and the vibration characteristic of the crystal vibrating element 56 is changed in temperature based on the temperature compensation data. There is provided a temperature compensation circuit that corrects it accordingly, an oscillation circuit that is connected to this temperature compensation circuit and generates a predetermined oscillation output, etc., and the oscillation output generated by the oscillation circuit is output to the outside of the device For example, it is used as a reference signal such as a clock signal.

  The plurality of connection terminals provided on the mounting side surface of the integrated circuit element 55 are disposed so as to correspond to the element connection electrode terminals provided on the inner bottom surface of the recess 60 of the wiring board 51, and these The integrated circuit element 55 is formed by individually bonding the connection terminal to the corresponding element connection electrode terminal via a bump such as Au, Au—Sn alloy or solder, or a conductive bonding material such as a conductive adhesive. At the same time, the connection terminal of the integrated circuit element 55 is electrically connected to the external connection electrode terminal 53. At the same time, the excitation electrode of the crystal resonator element 56 is electrically connected to the connection terminal of the integrated circuit element 55.

  The lid body 58 has an outline like a box having a substantially open shape, and the shape and size of the opening are the same as the outer peripheral shape (including the bonding material 59) and size of the stepped portion 61 formed on the wiring board 51. It is. The wiring board 51 is fitted into the opening of the lid 58 in such a manner that one main surface side surface of the stepped portion 61 formed on the side surface of the wiring board 51 is fitted to the inner surface of the lid body 58. The crystal resonator element 56 and the integrated circuit element mounted on one main surface of the wiring substrate 51 by closely bonding and bonding the bonding material 59 formed around the side surface of the lid body 58 and the inner surface of the side wall of the lid body 58. 55 is hermetically sealed. By fitting the opening of the lid body 58 into the stepped portion 61, the positioning of the lid body 58 can be facilitated when the lid body 58 is disposed on the wiring board 51.

  The lid 58 is electrically connected to the GND terminal of the external connection electrode terminals 53 formed on the other main surface of the wiring board 51 through the conductor layer 54 described above. Therefore, when the crystal oscillator is used, the lid body 58 is held at the ground potential, and the quartz resonator element 56 and the integrated circuit element 55 are caused to have an unnecessary electric action from the outside due to the shielding effect of the lid body 58, for example, Good protection from noise, etc.

  As another embodiment of the crystal oscillator according to the present embodiment, as shown in FIG. 10, the wiring board 51 extends from the surface of one main surface to each edge portion on the one main surface side of the wiring board 51. If the groove portion 62 having a depth component is formed in the thickness direction, even if the bonding material 59 flows into one main surface of the wiring board 51 during the bonding of the lid body 58, the flow-in bonding Since the material can be further prevented from flowing into the inside of the wiring substrate 51 by the groove 62, the bonding material does not adhere to the crystal vibration element 56 and the integrated circuit element 55, and stable vibration characteristics can be obtained. It becomes possible.

  Further, as shown in FIG. 11, the opening side wall end portion of the lid body 8 is disposed in the step portion 61, the bonding material 59 formed on the lid body 58 and the step portion 61 is joined, and it appears on the outer surface of the device. A resin layer 64 is provided on the surface of the lid 58, the wiring substrate 51, and the joint. By providing the resin layer 64, the airtightness can be further improved. In particular, since there may be a slight gap between the lid 58 and the bonding material 59 at the four corners of the device, the provision of the resin layer 64 is effective for further improving the airtightness. The resin layer 64 is formed of an epoxy resin and desirably has low fluidity.

  Further, as shown in FIG. 12, among the plurality of layers constituting the wiring board 51, the intermediate layer constituting one main surface side surface of each stepped portion except for one main surface side outermost layer of the wiring board 51. Even in a form in which the conductor layer 54 and the bonding material 59 are formed only on the side surfaces, the bonding material 59 is scattered and attached to the crystal resonator element 56 and the integrated circuit element 55 disposed on the outermost layer on one main surface side of the wiring substrate 51. Can be prevented.

  Furthermore, since the integrated circuit element 55 itself does not require an airtight space as its use environment, as shown in FIG. 13, a concave portion opened on the other main surface of the wiring board 51 not sealed by the lid 58. The present invention is also effective in a crystal oscillator in which 60b is formed, the integrated circuit element 55 is disposed in the recess 60b, and the corresponding terminals are mechanically and electrically connected.

Next, in the method for manufacturing the crystal oscillator described above, each step will be described with reference to FIGS.
(Process A)
First, as shown in FIG. 14, a master substrate 70 having a plurality of wiring substrate 51 regions arranged in a matrix is prepared, and a recess 60 formed on one main surface of each wiring substrate region of the master substrate 70 is prepared. Each of the integrated circuit elements 55 is mounted therein, and thereafter, the crystal vibration element 56 is mounted on the element connection electrode pad 52.

  The master substrate 70 includes, for example, at least two layers of rectangular flat plate substrates made of a ceramic material such as glass-ceramic and alumina ceramic, and have m columns × n rows (m and n are natural numbers of 2 or more). A plurality of wiring board 51 areas having a rectangular outer peripheral shape in the matrix form of. On each wiring board 51 area, a flat board having a similar outer peripheral shape to each wiring board area and having an outer peripheral dimension smaller than the outer circumference of the wiring board area is laminated and a stepped portion 61 is formed on the outer peripheral edge of each wiring board 51 area. Form. Each of the wiring substrate 51 regions set in a matrix form has one of the above-described pair of element connection electrode pads 52, the recess 60 and the stepped portion 61 surrounding each wiring substrate region on one main surface. A conductor layer 54 is formed on the side surface on the main surface side. In addition, an external connection electrode terminal 53 serving as an input / output terminal or a ground terminal is formed on the other main surface of each wiring board 51 region.

  Each layer constituting such a master substrate 70 has, for example, a recess 60, an electrode for electrode connection on the surface of a ceramic green sheet obtained by adding and mixing an appropriate organic solvent or the like to a ceramic material powder made of alumina ceramics or the like. A conductor paste to be a conductor pattern or the like provided on the pad 52, the external connection electrode terminal 53, and each wiring board region is printed and applied in a predetermined pattern, and the necessary number of layers are laminated and press-molded, and then fired at a high temperature. It is manufactured by.

  Further, the conductor layer 54 formed on one main surface side surface of the stepped portion 61 formed on the outer peripheral edge of each wiring board 51 region is formed by sequentially depositing a Ni layer and an Au layer on the surface of W or Mo. A bonding material 59 made of gold tin (Au—Sn) is deposited on the surface of the conductor layer 54. The bonding material 59 functions as a brazing material for bonding the lid body 58 to the wiring board 51. The composition ratio of gold-tin is approximately 80% gold and 20% tin, and the thickness is approximately. It is formed with a thickness of 10 μm to 30 μm.

  An integrated circuit element 55 is mounted in the recess 60 formed in each wiring board 51 region of the master substrate 70 formed in this manner, and a crystal resonator element 56 is provided on one main surface of each wiring board 51 region. Is mounted, and the excitation electrode of the crystal resonator element 56 and the corresponding connection terminal of the integrated circuit element 55 are connected to the element connection electrode pad 52 on one main surface in each wiring board 51 region and the conductive adhesive. Electrical connection is made via 57.

  Furthermore, as another embodiment of the present invention, in the vicinity of the outer periphery of one main surface of each wiring board region constituting the master substrate 70, the wiring board region is formed in a surrounding form from one main surface of each wiring substrate region. By providing the groove portion 62 (not shown in FIG. 14) having a depth component in the thickness direction, even when the bonding material 59 flows out when the lid body 58 and the bonding material 59 are bonded in a process to be described later, the groove 62. Therefore, the bonding material 59 does not adhere to the crystal resonator element 56 and the integrated circuit element 55, so that stable oscillation characteristics can be obtained.

(Process B)
Next, as shown in FIG. 15, the outer peripheral shape is a substantially box shape, and the shape of the opening on one main surface side of the step portion 61 formed in each wiring board 51 region (including the bonding material 59). The same lid body 58 is disposed on one main surface of each wiring board 51 region of the master substrate 70 so that the opening portion of the lid body 58 is fitted to the stepped portion 61, and the side wall portion of the lid body 58 is arranged. The inner surface and the bonding material 59 are bonded, and the quartz crystal vibration element 56 mounted on one main surface of each wiring board region and the integrated circuit element 55 in the recess 60 are hermetically sealed.

  The lid body 58 is manufactured, for example, by processing a metal plate having a thickness of 60 μm to 100 μm made of a metal such as 42 alloy, Kovar, or phosphor bronze into a predetermined shape by a conventionally known sheet metal processing. The lid 58 is formed by pressing a plate-like metal into a box shape, and a nickel (Ni) layer is formed on the inner surface of the lid 58.

  The outer peripheral edge portion of each wiring board 51 region of the master substrate 70 is configured such that the lid body 58 having such a configuration covers the crystal vibration element 56 on the corresponding wiring substrate 51 region and the integrated circuit element 55 in the recess 60. And placed in a heating furnace maintained at a temperature of 300 ° C. to 350 ° C., and the joining material 59 formed on the step portion 61 is heated and melted at a high temperature. Thus, the lid body 58 is joined to the stepped portion 61 of each wiring board region. Thereafter, the integrated master substrate 70 and the plurality of lids 58 are gradually cooled to room temperature. 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 an inert gas is contained in the internal space in which the crystal resonator element 5 is accommodated. Since the liquid crystal is filled or evacuated, it is possible to effectively prevent the quartz resonator element 5 from being corroded or deteriorated by oxygen, moisture in the atmosphere, or the like.

(Process C)
Finally, as shown in FIG. 16, in step B, the master substrate 70 in which the lid body 58 is bonded to each wiring board 51 region is collectively cut along the outer periphery of each wiring board 51 region, and individual crystal oscillators are obtained. Get. The master substrate 70 is cut by, for example, collectively cutting the master substrate 70 from the master substrate side using a dicer or the like, thereby obtaining a plurality of crystal oscillators simultaneously. As shown in FIG. 11, after the master substrate is cut and individual crystal oscillators are formed, the lid 58 and the wiring substrate 51 appearing on the outer surface of the crystal oscillator, and the resin layer made of epoxy resin on the surface of the joint portion 64 is applied by a dispenser and cured by irradiation with heat or the like. This can increase the joint strength and further improve the airtightness.

  In addition, in this case, since the master substrate 70 itself functions as a carrier when the crystal oscillator is assembled, the complicated operation of assembling the crystal oscillator by holding the separated wiring boards individually on the carrier is not necessary. This eliminates the need for any of them, which greatly simplifies the process of assembling the crystal oscillator, and makes it possible to improve the productivity of the crystal oscillator. In the manufacturing method disclosed in the second embodiment, the bonding material 59 is melted and sealed using a heating furnace. However, the bonding material 59 is heated and melted by irradiation with a laser or the like to perform hermetic sealing. It does not matter how you do it.

  The present invention is not limited to those described in the first embodiment and the second embodiment, and various changes and improvements can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the material using the quartz crystal as the material of the piezoelectric vibration element is exemplified. However, in addition to the crystal, lithium tantalate, lithium niobate, or piezoelectric ceramic is used as long as the material has a piezoelectric effect. You can use it. In the above-described embodiment, a piezoelectric (quartz) vibrator and a piezoelectric (quartz) oscillator are illustrated as an example of a piezoelectric device. However, other piezoelectric vibrations such as a surface acoustic wave (SAW) filter are used as piezoelectric vibration elements. The present invention is also applicable when using an element.

FIG. 1 is an exploded perspective view showing an embodiment of a piezoelectric device according to the present invention, taking as an example a crystal resonator that is one of the piezoelectric devices. FIG. 2 is a cross-sectional view showing a case where the crystal resonator shown in FIG. 1 is assembled. FIG. 3 is a cross-sectional view showing another embodiment of a crystal resonator (piezoelectric device) according to the present invention. FIG. 4 is a cross-sectional view showing another embodiment of a crystal resonator (piezoelectric device) according to the present invention. FIG. 5 is a cross-sectional view showing another embodiment of a crystal resonator (piezoelectric device) according to the present invention. FIG. 6 is a view showing one step (step A) of the manufacturing process of the crystal resonator (piezoelectric device) according to the present invention. FIG. 7 is a view showing one process (process B) of the manufacturing process of the crystal resonator (piezoelectric device) according to the present invention. FIG. 8 is a diagram showing one process (process C) of the manufacturing process of the crystal resonator (piezoelectric device) according to the present invention. FIG. 9 is a cross-sectional view showing another embodiment of the piezoelectric device according to the present invention, taking a crystal oscillator as one of the piezoelectric devices as an example. FIG. 10 is a sectional view showing another embodiment of the crystal oscillator (piezoelectric device) according to the present invention. FIG. 11 is a cross-sectional view showing another embodiment of the crystal oscillator (piezoelectric device) according to the present invention. FIG. 12 is a sectional view showing another embodiment of the crystal oscillator (piezoelectric device) according to the present invention. FIG. 13 is a sectional view showing another embodiment of a crystal oscillator (piezoelectric device) according to the present invention. FIG. 14 is a diagram showing one process (process A) of the manufacturing process of the crystal oscillator (piezoelectric device) according to the present invention. FIG. 15 is a view showing one process (process B) of the manufacturing process of the crystal oscillator (piezoelectric device) according to the present invention. FIG. 16 is a view showing one process (process C) of the manufacturing process of the crystal oscillator (piezoelectric device) according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51 ... Wiring board 2,52 ... Electrode connection electrode pad 3,53 ... External connection electrode terminal 4,54 ... Conductive layer 5,56 ... Crystal vibration element (piezoelectric vibration) element)
6 ... Excitation electrode 7,57 ... Conductive adhesive 8,58 ... Cover body 9,59 ... Joint material 10,70 ... Master substrate 11,61 ... Step 12, 62 ... groove 14, 64 ... resin layer 55 ... integrated circuit element 60 ... concave

Claims (6)

A wiring board and a box fixed to the wiring board in a form in which at least a piezoelectric vibration element is arranged on one main surface of the wiring board and covering one main surface of the wiring board on which the piezoelectric vibration element is arranged In a piezoelectric device consisting of a shaped lid,
A convex stepped portion is provided on one side of the wiring substrate on the side surface of the wiring substrate, a bonding material is formed on the side surface of the stepped portion, and the inner surface of the side wall of the lid and the bonding material are A piezoelectric device, wherein an internal space formed by joining and formed by one main surface of the lid and the wiring board is hermetically sealed.   2. The piezoelectric element according to claim 1, wherein a groove portion having a depth component in a thickness direction of the wiring substrate from the surface of the one main surface is provided at an edge portion of the one main surface of the wiring substrate. device.   The piezoelectric device according to claim 1, wherein a resin layer is provided on the surface of the lid, the wiring board, and the joint portion that are exposed on the outer surface of the device. A convex step portion is provided on one main surface of each wiring board region at each outer peripheral edge portion of the plurality of wiring board regions arranged in a matrix, and a bonding material is formed on the side surface of each step portion. Preparing a master substrate, and mounting at least a piezoelectric vibration element on one main surface of each wiring board region in the master substrate; and
A box-shaped lid for hermetically sealing the space in which the piezoelectric vibration element is mounted is covered on one main surface of each wiring board region of the master substrate, and the inner surface of the side wall of the lid And step B for bonding the bonding material and
Step C for simultaneously obtaining a plurality of piezoelectric devices by collectively cutting and separating along the outer periphery of each wiring board region of the master substrate;
A method for manufacturing a piezoelectric device comprising:   5. The groove portion having a depth component in the thickness direction of the wiring board region from the surface of one main surface is provided at an outer peripheral edge of one main surface of each wiring board region. A method for manufacturing a piezoelectric device.   5. The piezoelectric device according to claim 4, further comprising a step of providing a resin layer on a surface of the lid, the wiring substrate, and the joint portion that are exposed on the outer surface of each piezoelectric device after cutting the master substrate. Production method.

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