JP2009246613A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device that prevents a solder fillet part from contacting with a lid or a sealing material so as to prevent the occurrence of trouble due to the contact between the solder fillet part and the lid or the sealing material and achieves simplification of a loading process. <P>SOLUTION: The piezoelectric device 10 is composed of a container 11 formed with a recess 15, a sealing material 18 provided on the top face on the side of an opening of the recess 15 at the sidewall part of the container 11, a piezoelectric vibration element 12 loaded inside the recess 15, each electrode 17 for external connection formed on the outside bottom face of the container 11, and a metal lid 13 arranged on the sealing material 18 so as to airtightly seal the inside of the recess 15 by being joined to the sealing material 18. A part of the outside side face of the sidewall part of the container 11, the sealing material 18 exposed outside the piezoelectric device 10, and the surface of the lid 13 are covered by a heat-resistant insulating layer 14 formed of a silicon dioxide or an aluminum oxide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piezoelectric device that is one of electronic components.

  Piezoelectric devices such as piezoelectric vibrators and piezoelectric oscillators that have a piezoelectric resonator inside are used as one of electronic components, as a reference signal source or clock signal source, inside an electronic device such as a computer, mobile phone, or small information device. Installed and used.

  FIG. 5 is an exploded perspective view showing a conventional piezoelectric vibrator. 6 is a cross-sectional view taken along a cutting line AA shown in FIG. As shown in FIGS. 5 and 6, the piezoelectric vibrator 100 mainly includes a container body 101, a piezoelectric vibration element 110, and a lid body 120.

  The piezoelectric vibration element 110 is electrically connected to a vibration electrode, a frequency adjustment electrode, or a container body to be accommodated on the surface of a crystal base plate 111 having a planar-view tuning fork type outer shape using quartz as a piezoelectric material. It is comprised by forming various electrodes, such as a container body connection electrode used for taking. The quartz base plate 111 has a thickness dimension of, for example, about 100 μm, and is roughly constituted by a base portion 112 and two vibrating arm portions 113 formed so as to protrude from one side of the base portion 112 in the same direction. Such a tuning-fork type outer shape of the quartz base plate 111 is generally made by a photolithography technique and a chemical etching technique.

The piezoelectric vibration element 110 is mounted in a recess 102 having an outer shape made of an insulating material provided in a substantially rectangular parallelepiped container body 101 and having an opening on one main surface of the container body 101. The piezoelectric vibration element 110 mounted in the recess 102 is electrically connected to a predetermined terminal among the external connection electrode terminals 103 formed on the outer bottom surface of the container body 101. Further, the concave portion 102 on which the piezoelectric vibration element 110 is mounted covers the opening 102 of the concave portion 102 with a metal lid 120, and the sealing material 104 provided on the top surface of the side wall portion of the container body 101 on the concave portion 102 opening side. Are joined and hermetically sealed. Further, an Au—Sn alloy is used as the material of the sealing material 104. (For example, see Patent Document 1)
In addition to the tuning fork type, the outer shape of the piezoelectric vibration element is, for example, a circular shape or a rectangular shape in plan view, or a rectangular shape in plan view, and the thickness of the excitation portion of the piezoelectric vibration element is a thickness other than the excitation portion. There is a so-called inverted mesa type that is processed thinner.

  As a piezoelectric device, in addition to the piezoelectric vibrator described above, a piezoelectric vibration element and an integrated circuit element including an oscillation circuit electrically connected to the piezoelectric vibration element are provided in a recess in the container body. There are mounted piezoelectric oscillators (for example, see Patent Document 2) and piezoelectric filters (for example, see Patent Document 3) in which a piezoelectric vibration element mounted inside functions as a filter.

  Piezoelectric devices such as piezoelectric vibrators and piezoelectric oscillators are currently becoming thinner, and those having a thickness dimension of 1 mm or less have been developed and manufactured. In addition, such piezoelectric devices include external connection electrode terminals and electronic circuits using heating means such as reflow for external electronic circuit wiring formed on a motherboard or the like together with other electronic components such as resistors and capacitors. It is mounted by conducting and fixing between the wiring with solder paste.

  Therefore, in the conventional piezoelectric device, a part of the external connection electrode terminal provided on the outer bottom surface of the container body is extended to the side surface of the container body. A solder fillet is formed on the external connection electrode terminal in a portion extending on the side surface of the container body when the conductive terminal is fixed by soldering. This fillet enhances the bonding force between the external connection electrode terminal and the electronic circuit wiring, and allows the solder bonding state to be visually recognized from the outside (for example, see Patent Document 4).

JP 2006-229283 A JP 2006-54321 A JP-A-9-33228 JP 2002-208765 A

  In addition, other than the prior art documents specified by the prior art document information described above, no prior art documents related to the present invention have been found by the time of filing of the present application.

  However, in the piezoelectric device in which the electrode terminal for external connection extends to the side surface of the container body, when the thickness is further reduced, depending on the amount of solder conductively joined to the external electronic circuit wiring formed on the mother board or the like, The height of the creeping part to the side surface of the solder container body becomes high. For this reason, the solder fillet scooped up high comes into contact with the metal lid and the sealing material, and in particular, easily comes into contact with the sealing material at a position closer to the external connection electrode terminal than the lid. This contact may cause a short circuit between different external connection electrode terminals via the lid or the sealing material.

  In addition, when a solder containing silver as a eutectic component is used as a solder for conductively joining a piezoelectric device, the fillet portion of the solder is made of an Au—Sn alloy that joins the container body and the lid body. When it comes into contact with the sealing material, the eutectic temperature of the Au—Sn alloy in the contacted portion may be lowered due to the influence of the silver component of the solder. When the eutectic temperature of the sealing material is partially reduced, unevenness occurs in the bonding form due to melting and solidification of the sealing material, and the hermetic sealing between the container body and the lid body may be poor.

  Furthermore, in order to precisely control the size of the fillet, the amount of solder is adjusted for each type of electronic component including the piezoelectric device mounted on the motherboard, and the optimal amount of solder for each electronic component to be connected is precisely controlled. There is a need. This management work is very complicated, and the process of mounting electronic components on the motherboard may become complicated, and the mounting process time may be extended.

  An object of the present invention is to provide a piezoelectric device in which a solder fillet does not come into contact with a lid or a sealing material, does not cause problems due to the contact, and simplifies the mounting process on a mother board or the like. There is.

  The present invention has been made to solve the above-mentioned problems. A container body in which a recess having an opening is formed on one main surface, and a recess opening side apex in a side wall of the container body surrounding the recess. A plurality of external devices including a sealing material provided on the surface, a piezoelectric vibration element mounted in the recess, and an electrical connection with the piezoelectric vibration element provided from the outer bottom surface to the side surface of the container body A piezoelectric device comprising a connection electrode and a metal lid that is disposed on a sealing material so as to cover the opening of the concave portion and hermetically seals the inside of the concave portion by bonding to the sealing material. And a part of the outer side surface of the side wall portion of the container body and the surface of the sealing material and the lid body exposed to the outside of the piezoelectric device are covered with a heat resistant insulating layer made of silicon dioxide or aluminum oxide. It is a piezoelectric device characterized by having.

  Or, a container body in which a recess having an opening is formed on one main surface, a sealing material provided on the top surface on the recess opening side of the side wall of the container body surrounding the recess, and mounted in the recess A plurality of external connection electrode portions including those electrically connected to the piezoelectric vibration element, which are provided from the outer bottom surface to the side surface of the container body, and at least electrically connected to the piezoelectric vibration element An integrated circuit element containing the oscillation circuit, and a metal lid that is disposed on the sealing material so as to cover the opening of the concave portion and hermetically seals the concave portion by bonding with the sealing material. A piezoelectric device configured, wherein a part of the outer side surface of the side wall portion of the container body and the surface of the sealing material and the lid exposed to the outside of the piezoelectric device are made of silicon dioxide or aluminum oxide. Be covered by an insulating layer A piezoelectric device to symptoms.

  Further, the piezoelectric device is the piezoelectric device described above, wherein the sealing material is an Au—Sn alloy.

  In the piezoelectric device of the present invention, even when solder fills up to the side of the container body by the external connection electrode terminal extending to the side of the container body, and the fillet portion of the solder reaches the height of the lid body, The heat-resistant insulating layer made of silicon dioxide or aluminum oxide provided over the surface of the lid can prevent the solder fillet portion from coming into contact with the metal lid or sealing material. Therefore, a short circuit between different external connection terminals can be prevented by the solder in which the fillet portion is formed. In particular, when using lead-free solder with a high eutectic temperature, using a heat-resistant insulating layer made of silicon dioxide or aluminum oxide, which has higher heat resistance compared to resin, etc., the solder fillet is more reliably made of metal. Contacting the lid or the sealing material can be prevented.

  Moreover, even when using a solder containing silver as a eutectic component, by providing this heat-resistant insulating layer, it is possible to prevent the fillet portion of the solder from coming into contact with the Au-Sn alloy sealing material. Can do. Therefore, the eutectic temperature of the sealing material is not partially lowered due to the influence of the solder contact, and the bonding form of the sealing material is constant throughout the sealing material, and the hermetic sealing between the container body and the lid body The state becomes good.

  Further, by using the piezoelectric device having the structure as in the present invention, even when a large amount of solder is used for the piezoelectric device when the piezoelectric device is mounted on the mother board, the solder fillet portion is not covered by the lid or seal. Since there is no contact with the stop material, it is possible to prevent the occurrence of problems caused by the contact. Therefore, it is not necessary to use a complicated process for precisely managing the optimal amount of solder for each type of electronic component connected to the motherboard. For example, it is possible to use a process in which solder is collectively provided at the electronic component mounting position of the mother board by a simple method such as printing means using a mask, and electronic components including piezoelectric devices are collectively mounted by reflow means. The time required for the component mounting process can be shortened.

  Therefore, according to the present invention, the solder fillet formed on the external connection electrode terminal of the piezoelectric device does not come into contact with the lid or the sealing material, and the external connection electrode terminals are short-circuited via the lid. In addition, there is an effect that it is possible to provide a piezoelectric device that does not cause poor hermetic sealing and can simplify the mounting process.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Note that, in each embodiment, the same components are denoted by the same reference numerals. In addition, in the drawings, for the sake of clarity, some of the components are not shown, and some of the illustrated dimensions are exaggerated. In particular, the dimension in the thickness direction of each component is exaggerated.

(First embodiment)
FIG. 1 is an external perspective view showing a piezoelectric device according to a first embodiment of the present invention. FIG. 2 is an enlarged view of a portion C in FIG. 3 is a schematic cross-sectional view taken along the cutting line BB in FIG. A piezoelectric device 10 shown in FIGS. 1 to 3 is a piezoelectric vibrator, and is mainly composed of a container body 11, a piezoelectric vibration element 12, a lid body 13, and a heat-resistant insulating layer 14.

  As shown in FIGS. 1 and 3, the container body 11 includes a substrate 11a whose outer shape is a flat plate having a rectangular shape in plan view, and a frame 11b whose outer peripheral size is the same as that of the substrate 11a. The container body 11 has a substantially rectangular parallelepiped outer shape by joining the frame body 11b to one main surface of the substrate 11a with the outer periphery of each main surface aligned. The container body 11 is formed with a recess 15 (see FIG. 3) surrounded by one main surface of the substrate 11a and the inner surface of the frame body 11b by joining the substrate 11a and the frame body 11b. The substrate 11a and the frame 11b are configured by firing a ceramic material such as glass-ceramic or alumina ceramic.

  As shown in FIG. 3, in the vicinity of one short side of the inner bottom surface of the recess 15, two pairs of piezoelectric vibration element connecting electrode pads 16 are provided along the short side. The piezoelectric vibration element connection electrode pad 16 is electrically connected to a predetermined terminal among the external connection electrode terminals 17 provided at each corner of the other main surface of the substrate 11a. A part of the external connection electrode terminal 17 has a shape in which the inside of the rounded side surface of the container body 11 extends from the outer bottom surface of the container body 11 toward the opening of the recess 15.

  Further, a sealing material 18 is provided on the top surface of the side wall of the container 11 surrounding the recess 15 on the opening side of the recess 15. This sealing material 18 is provided in a strip shape over the entire circumference of the top surface on the opening side of the recess 15 in the side wall of the container body 11, and the material thereof is an Au—Sn alloy.

  The piezoelectric vibration element 12 includes a quartz base plate made of a piezoelectric quartz crystal and electrodes provided on the surface thereof. The quartz base plate was cut out from the artificial crystalline lens at a predetermined cut angle, and the outer shape was processed into a flat plate shape in a plan view tuning fork shape including a base portion 12a and two vibrating arm portions 12b extending in the same direction from one side of the base portion 12a. Is. The piezoelectric vibration element 12 has a vibration electrode and a frequency adjustment electrode on the surface of the vibrating arm portion 12b, a container body connection electrode, a vibration electrode and a container body connection electrode on the surface of the base portion 12a. It is comprised by providing the extraction electrode connected electrically. In the piezoelectric vibration element 12, when a fluctuation voltage from the outside is applied to the quartz base plate via the vibration electrodes on both main surfaces, the vibration arm portion of the piezoelectric vibration element vibrates at a predetermined frequency value in the bending vibration mode. Is supposed to wake up.

  The lid 13 is made of a metal such as 42 alloy, Kovar, or phosphor bronze, and the planar view shape is a rectangular flat plate. Further, the outer peripheral size of the main surface of the lid 13 is such that when the lid 13 covers the opening of the concave portion 15 of the container body 11, the main body of the lid body 13 is formed on the top surface of the concave portion opening side of the frame 11 b constituting the container body 11. The outer peripheral edge of the surface is large enough to be placed.

  The piezoelectric vibration element 12 is disposed on the piezoelectric vibration element connection electrode pad 16 provided on the inner bottom surface of the recess 15 of the container body 11 so that the container body connection electrode provided on the piezoelectric vibration element 12 is opposed to the piezoelectric vibration element 12. . The container body connection electrode and the piezoelectric vibration element connection electrode pad 16 of the piezoelectric vibration element 12 are conductively fixed by a conductive adhesive 19. Moreover, the cover body 13 is arrange | positioned in the form which covers the opening part of the recessed part 15 on the sealing material 18 provided on the top surface by the side of the recessed part 15 opening of the frame 11b. The concave portion 15 in which the piezoelectric vibration element 12 is mounted is hermetically sealed by fixing the lid 13 to the container body 11 through a sealing material 18 which is melted by the heating means and then solidified.

  As shown in FIGS. 1 and 3, the piezoelectric device 10 is exposed to the outside of the piezoelectric device of the lid body 13 from a part of the outer side surface of the container body 11 to which the lid body 13 is bonded via the sealing material 18. A heat-resistant insulating layer 14 made of a heat-resistant insulating material is provided over the surface. Silicon dioxide or aluminum oxide is used as the material of the heat-resistant insulating material constituting the heat-resistant insulating layer 14. The heat-resistant insulating layer 14 continues to be interposed between the solder and the sealing material 18 or the lid 13 even when the heat-melted solder fillet portion adheres to the heat-resistant insulating layer 14. 18 or heat resistance that can prevent electrical and mechanical contact with the lid 13. As a method for forming the heat-resistant insulating layer 14, when silicon dioxide or aluminum oxide is used as a material, it is formed using a sputtering method or a vapor deposition method.

  Since the piezoelectric device 10 has such a structure provided with the heat-resistant insulating layer 14, when the piezoelectric device 10 is mounted on an external electronic circuit board, a solder fillet portion formed on the external connection electrode terminal 17. However, there is no electrical and mechanical contact with the metal lid 13 or the sealing material 18. Therefore, in the piezoelectric device 10, when the solder in which the fillet is formed contacts the lid body 13 or the sealing material 18, the different external connection terminals 17 are short-circuited via the lid body 13 or the sealing material 18. Can be prevented. In particular, when Sn-Cu-Ag or Sn-Ag lead-free solder having a higher eutectic temperature than Sn-Pb solder is used, silicon dioxide or aluminum oxide, which has higher heat resistance than resin or the like, is used. By using the heat-resistant insulating layer 14 as described above, it is possible to more reliably prevent the solder fillet portion from coming into contact with the metal lid 13 or the sealing material 18.

  Further, when an Au—Sn alloy is used as the material of the sealing material 18, when the solder containing the silver component comes into contact with the sealing material 18, the contacted portion is affected by the silver component contained in the solder. The eutectic temperature of the sealing material 18 decreases from about 283 ° C. to about 210 ° C. When heat of 240 ° C. is applied to a piezoelectric device hermetically sealed with a sealing material having a portion where the eutectic temperature has decreased to about 210 ° C., for example, in a reflow process, the portion where the eutectic temperature has decreased is sealed. There is a possibility that the stopper is melted and softened and the airtightness in the recess 15 cannot be maintained. Therefore, the heat resistant insulating layer 14 prevents the solder containing the silver component from coming into contact with the sealing material 18 in the piezoelectric device 10 using the sealing material 18 of the Au—Sn alloy. Thereby, in the piezoelectric device 10, the eutectic temperature of the Au—Sn alloy that is the sealing material 18 is not partially lowered, and the bonding form of the sealing material 18 becomes constant throughout the sealing material 18. The hermetic sealing of the device 10 can be maintained well.

  Furthermore, by using the piezoelectric device 10 having a structure provided with the heat-resistant insulating layer 14, a large amount of solder is used with respect to the piezoelectric device 10 when the piezoelectric device 10 is connected to an external electric network such as a mother board. However, since the fillet portion of the solder does not come into contact with the lid 13 or the sealing material 18, it is possible to prevent the occurrence of the problems due to the contact as described above. Therefore, it is not necessary to use a complicated process for precisely managing the optimal amount of solder paste for each type of electronic component connected to the motherboard. For example, it is possible to use a process in which solder is provided at an electronic component mounting position on a motherboard by a simple method such as printing means using a mask, and electronic components including the piezoelectric device 10 are collectively mounted by reflow means. The mounting process time can be shortened.

(Second Embodiment)
FIG. 4 is a schematic cross-sectional view showing a piezoelectric device according to the second embodiment of the present invention. The piezoelectric device 40 shown in FIG. 4 is a so-called piezoelectric oscillator. In the second embodiment, in addition to the piezoelectric vibration element 12 in the recess 42 formed in the container body 41, an alternating voltage is supplied to the piezoelectric vibration element 12, and an output signal having a predetermined frequency value is output from the piezoelectric vibration element 12. In the first embodiment, an integrated circuit element 44 that includes at least a built-in oscillation circuit and is electrically connected to the external connection electrode terminal 43 provided on the outer bottom surface of the container body 41 is mounted. It is different from the form.

  Also in the piezoelectric device 40 having such a configuration, as in the first embodiment, the heat-resistant insulating layer 45 has a part of the outer side surface of the container body 41 and the sealing material 47 exposed to the outside of the piezoelectric device 40. And a surface of the lid 46 so as to cover the surface. By providing this heat-resistant insulating layer 45, the solder fillet formed on the external connection electrode terminal 43 of the piezoelectric device 40 comes into contact with the lid 46 and the sealing material 47, as in the first embodiment. Piezoelectric device that does not cause short circuit through the lid 46 between different external connection electrode terminals 43 or a hermetic sealing failure due to a decrease in the eutectic temperature of the sealing material 47 and can simplify the mounting process. The effect which can provide 40 is produced.

  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 each of the above embodiments, the planar-viewing tuning fork type piezoelectric vibration element 12 using quartz as a piezoelectric material has been illustrated. However, as the piezoelectric vibration element using quartz, there are other piezoelectric elements having a circular shape or a rectangular shape in plan view. A vibration element may be used. In addition, piezoelectric materials other than quartz are also used in such a circular or rectangular piezoelectric vibration element in plan view, and for example, piezoelectric materials such as lithium tantalate, lithium niobate, or piezoelectric ceramics can be used. .

1 is an external perspective view showing a piezoelectric device according to a first embodiment of the present invention. It is an enlarged view of the C section of FIG. It is the schematic sectional drawing cut | disconnected by the cutting line BB of FIG. It is the schematic sectional drawing which showed the piezoelectric device which concerns on the 2nd Embodiment of this invention. It is the disassembled perspective view which showed the conventional piezoelectric vibrator. It is sectional drawing cut | disconnected by the cutting line AA of FIG.

Explanation of symbols

10 ... Piezoelectric device (piezoelectric vibrator)
DESCRIPTION OF SYMBOLS 11,41 ... Container body 11a ... Board | substrate 11b ... Frame body 12 ... Piezoelectric vibration element 12a ... Base part 12b ... Vibrating arm part 13, 46 ... Cover body 14,45. ..Heat-resistant insulating layers 15, 42 ... concaves 16 ... electrode pads for connecting piezoelectric vibration elements 17,43 ... electrode terminals for external connection 18,47 ... sealing material 19 ... conductive adhesive Agent 40 ... Piezoelectric device (piezoelectric oscillator)
44. Integrated circuit element

Claims (3)

A container body having a substantially rectangular parallelepiped shape and having a recess having an opening on one main surface;
A sealing material provided on the recess opening side top surface in the side wall portion of the container body surrounding the recess;
A piezoelectric vibration element mounted in the recess;
A plurality of external connection electrode terminals including those electrically connected to the piezoelectric vibration element provided from the outer bottom surface to the side surface of the container body;
A piezoelectric device that is arranged on the sealing material so as to cover the opening of the concave portion and is composed of a metal lid that hermetically seals the inside of the concave portion by bonding with the sealing material. ,
A part of the outer side surface of the side wall portion of the container body, the sealing material exposed to the outside of the piezoelectric device, and the surface of the lid body are covered with a heat-resistant insulating layer made of silicon dioxide or aluminum oxide. A piezoelectric device characterized by that. A container body having a substantially rectangular parallelepiped shape and having a recess having an opening on one main surface;
A sealing material provided on the recess opening side top surface in the side wall portion of the container body surrounding the recess;
A piezoelectric vibration element mounted in the recess;
An integrated circuit element including an oscillation circuit mounted in the recess and at least electrically connected to the piezoelectric vibration element;
A plurality of electrode terminals for external connection provided from the outer bottom surface to the side surface of the container body and electrically connected to an electronic circuit embedded in the integrated circuit element;
A piezoelectric device that is arranged on the sealing material so as to cover the opening of the concave portion, and is composed of a metal lid that hermetically seals the inside of the concave portion by bonding to the sealing material. ,
A part of the outer side surface of the side wall portion of the container body, the sealing material exposed to the outside of the piezoelectric device, and the surface of the lid body are covered with a heat-resistant insulating layer made of silicon dioxide or aluminum oxide. A piezoelectric device characterized by that.   The piezoelectric device according to claim 1 or 2, wherein a material of the sealing material is an Au-Sn alloy.

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