JP5026016B2 - Method for manufacturing piezoelectric device - Google Patents

Description

The present invention relates to a method for manufacturing a piezoelectric device, which is one of electronic components, in particular, to tower mounting method of a piezoelectric vibrating element mounted on a piezoelectric device.

  Currently, in electronic devices such as mobile communication devices such as mobile phones and digital home appliances, piezoelectric devices such as piezoelectric vibrators, piezoelectric oscillators or piezoelectric filters are mounted as one of the electronic components. The piezoelectric oscillator is used as a reference signal generation source and timing device in an electronic apparatus, and the piezoelectric filter is used as a device that extracts only a signal having a desired frequency from a received signal. In recent years, with the remarkable miniaturization of electronic devices, further miniaturization is required for piezoelectric devices used in these electronic devices.

  A piezoelectric vibrator, which is one piezoelectric device, will be described as an example. A piezoelectric vibration element used in the piezoelectric vibrator includes an excitation electrode for exciting the piezoelectric piece on the front and back main surfaces of the piezoelectric piece, and a piezoelectric vibration element. Forming a substrate connection electrode for connecting to an element connection electrode pad formed on an insulating substrate on which the substrate is mounted, and a lead electrode for electrically connecting the excitation electrode and the substrate connection electrode Has been. The so-called strip shape, which is advantageous for downsizing, has become the mainstream as the shape of the piezoelectric vibration element.

  FIG. 4 shows the length of a piezoelectric vibrator 40 having a structure in which the piezoelectric vibration element 41 having the above-mentioned various electrodes formed thereon is mounted on an insulating substrate 46 and conductively fixed by a conductive adhesive 48 as an example of the prior art. It is sectional drawing of a direction. That is, on the front and back main surfaces of the piezoelectric piece 42 constituting the flat plate-like piezoelectric vibration element 41 having a rectangular main surface shape, the excitation electrode 43 opposed to the piezoelectric piece 42 and the excitation electrode 43 from the excitation electrode 43 are piezoelectric. Lead electrodes extending to short sides in different directions on the front and back main surfaces of the piece 42 are formed, and are further electrically connected to the lead electrodes and to an element connecting electrode pad 47 on the insulating substrate 46 side to be described later. Substrate connection electrodes 45 for conducting are formed on both short side edges of the piezoelectric piece 42.

  The piezoelectric vibration element 41 configured as described above is disposed in an airtight space formed by the insulating substrate 46 and a lid body 49 described later. At that time, a conductive adhesive is provided between the substrate connection electrode 45 on the piezoelectric vibration element 41 side and the element connection electrode pad 47 formed of a metal such as gold on one main surface of the insulating substrate 46. 48 is used for conducting connection. Further, the conductive adhesive 48 is heated and solidified to hold the posture of the piezoelectric vibration element 41 on the insulating substrate 46.

  A box-shaped metal lid 49 having an opening with a flange formed on one main surface of the insulating substrate 46 on which the piezoelectric vibration element 41 is mounted in this manner, and the piezoelectric vibration element 41 as the lid body 49. The piezoelectric vibrator 40 is formed by arranging so as to be housed in the internal space and hermetically sealing the flange portion of the lid 49 and one main surface of the substrate 46 via a sealing material.

  As another piezoelectric device, a piezoelectric vibration element and an integrated circuit element including an oscillation circuit electrically connected to the piezoelectric vibration element are mounted together in a recessed space in a ceramic container. Piezoelectric oscillators and piezoelectric filters in which a piezoelectric vibration element mounted inside a package functions as a filter.

The following documents are disclosed for the piezoelectric device having the above-described structure.
Japanese Patent Laid-Open No. 10-32430 Japanese Patent Laid-Open No. 10-51265 JP 2001-94385 A

  In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

  In a piezoelectric device such as the above-described piezoelectric vibrator, a conductive adhesive is usually applied to an element connection electrode pad formed on a container body, and the piezoelectric adhesive is formed on the conductive adhesive for external connection. The piezoelectric vibrating element is arranged in contact with the electrode. If necessary, a conductive adhesive is further applied on the external connection electrode and conductive adhesive. Because the adhesive is soft and fluid, it is difficult to maintain the orientation of the piezoelectric vibration element. In the worst case, a part of the piezoelectric vibration element is attached to the container body or lid as shown in FIG. As a result, they may come into contact with each other, which may cause a significant defect in the vibration characteristics of the piezoelectric vibration element.

  In addition, a conductive adhesive is used for direct adhesion between the external connection electrode formed on the piezoelectric vibration element and the element connection electrode pad. When a certain amount of conductive adhesive is applied between the external connection electrode and the element connection electrode pad and directly fixed, the conductive adhesive must be solidified to cause the conductive adhesive to have a fixing effect. However, since the solidified bonding material has conductivity, the hardness is increased due to the metal component contained therein, and the area where the conductive adhesive adheres to the piezoelectric vibration element is relatively wide. In some cases, the vibration of the bonded piezoelectric vibration element is suppressed, and the vibration characteristics of the piezoelectric vibration element are deteriorated. In addition, since the surface of the element connection electrode pad made of metal is very smooth, there is a concern that the bonding force between the element connection electrode pad and the bonding material is weakened when the bonding material is adhered and solidified. is there.

  In addition, heating and ultraviolet irradiation are performed to solidify the conductive adhesive, but a certain time is required to solidify the conductive adhesive to a predetermined hardness and stabilize the characteristics. There is a concern. In addition, since many conductive adhesives use organic substances such as epoxy and silicone as binders, their properties such as conductivity and hardness change with external heating and time after solidification. Therefore, there is a possibility of adversely affecting the characteristics of the piezoelectric device using the conductive adhesive.

The present invention has been made to solve the above-described problems, and at least a pair of element connection electrode pads is formed on one surface of an insulating substrate, and a piezoelectric vibration element is formed on the element connection electrode pads. And electrically and mechanically connect a pair of substrate connecting electrodes and element connecting electrode pads formed on the surface of the piezoelectric vibration element between each opposing substrate connecting electrode and element connecting electrode pad. In the method of manufacturing a piezoelectric device that is fixedly connected and further hermetically seals the space in which the piezoelectric vibration element is mounted with a lid,
Forming a nickel plating layer on each element connection electrode pad, on which at least one nickel ball or at least one projecting protrusion protruding toward the piezoelectric vibration element side is formed;
A step of disposing the piezoelectric vibration element on the nickel ball or the nickel plating layer in a form in which the substrate connection electrode formed on the piezoelectric vibration element is opposed to the convex portion of the nickel ball or the nickel plating layer;
A voltage is applied between the convex portion of the nickel ball or nickel plating layer and the substrate connecting electrode, and a nickel pillar is grown from the convex portion of the nickel ball or nickel plating layer toward the substrate connecting electrode. And a step of electrically and mechanically connecting and fixing the element connecting electrode pad and the substrate connecting electrode through the substrate.

  In the above-described piezoelectric device of the present invention, the electrical connection between the substrate connection electrode formed on the piezoelectric vibration element mounted in the piezoelectric device and the element connection electrode pad formed on the insulating substrate constituting the piezoelectric device. In addition, since the mechanical connection is made with a metal nickel pillar, the piezoelectric vibration element can be held on the insulating substrate in the desired orientation immediately after the nickel pillar is formed. Since the posture of the vibration element can be always held in the best state by the nickel pillar, it is possible to prevent the deterioration of the vibration characteristics due to the posture failure of the piezoelectric vibration element.

  Further, in the present invention, the bonding conduction between the piezoelectric vibration element and the insulating substrate through the fine nickel pillar is achieved, so that the area to be bonded and fixed is significantly smaller than the bonding conduction by the conductive adhesive. For this reason, it is possible to minimize the deterioration of the vibration characteristics of the piezoelectric vibration element due to the formation of the fixed conductive member. Further, since the conductive adhesive is not used in the piezoelectric device of the present invention, there is no deterioration in the characteristics of the piezoelectric device due to the change in the characteristics of the conductive adhesive.

  In addition, according to the method for manufacturing a piezoelectric device according to the present invention, an instantaneous voltage application is made to a metallic nickel pillar for electrical and mechanical connection between electrode pads for element connection formed on an insulating substrate constituting the piezoelectric device. Therefore, the manufacturing time of the piezoelectric device can be remarkably shortened as compared with the case using a conductive adhesive.

  By the above operation, there is an effect that it is possible to provide a piezoelectric device that is inexpensive and has excellent vibration characteristics of the piezoelectric vibration element mounted inside.

Hereinafter, embodiments of a piezoelectric device according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic exploded external view showing a piezoelectric vibrator according to the present invention as an example of a piezoelectric vibrator which is one of the piezoelectric devices. FIG. 2 is an enlarged view of a part of a cross-sectional view when the piezoelectric vibrator shown in FIG. 1 is assembled and then cut along a virtual cutting line A1-A2 shown in the figure. FIG. 3 is an enlarged partial cross-sectional view showing an enlarged portion of the dotted circle B shown in FIG. In each drawing, the same reference numerals indicate the same parts, and a part of the structure is not shown for clarity. Further, the dimensions of the structure shown in the figure are partially exaggerated.

  That is, in FIG. 1, FIG. 2 and FIG. 3, on the front and back main surfaces of the piezoelectric base plate 11 formed of a piezoelectric material such as quartz, lithium tantalate, lithium niobate or piezoelectric ceramics and having a strip-like outer shape. A substantially rectangular excitation electrode 12 is formed in the center of the piezoelectric element plate 11 by vapor deposition so that the front and back main surfaces are opposed to each other. A lead electrode 13 extending in the side direction and a substrate connecting electrode 14 electrically connected to the lead electrode 13 and connected to an element connecting electrode pad 16 formed in a container body 15 to be described later are provided. The piezoelectric vibration element 10 is configured by being formed on both short side edges of the piezoelectric element plate 11.

  The insulating substrate 15 on which the piezoelectric vibration element 10 having such a shape is mounted uses a plate-shaped ceramic material or glass epoxy material whose main surface is rectangular as a main structural material. On the surface, element connection electrode pads 16 are formed at positions facing the substrate connection electrodes 14 formed on both short side edges of the piezoelectric vibration element 10 when the piezoelectric vibration element 10 is mounted. Yes. In the present embodiment, the length dimension of the element connection electrode pad 16 is about half of the short side dimension of the piezoelectric vibration element 10, and the two element connection electrode pads 16 are based on the center point of the main surface of the insulating substrate. However, the length dimension of the element connection electrode pad 16 is set to the same dimension as the short side dimension of the piezoelectric vibration element 10, and two element connection electrode pads 16 are formed. You may form in the form which becomes line symmetrical with respect to the centerline which equally bisects the long side of an insulated substrate main surface.

  In addition, a sealing conductor pattern 18 for joining a lid body 17 to be described later is formed in an annular shape on each edge portion on one main surface of the insulating substrate 15. On the main surface, an external connection electrode terminal 19 is formed for electrical and mechanical connection with an electronic circuit pattern formed on an external mounting substrate. The external connection electrode terminal 19 and the element connection electrode pad 16 are electrically connected by a conductive wiring or via hole formed on the insulating substrate 15 between the external connection electrode terminal desired to be connected and the element connection electrode pad. Has been.

  The piezoelectric vibration element 10 on which the above-described various electrodes are formed is arranged on one main surface of the substrate 15 so that the substrate connection electrode 14 of the piezoelectric vibration element 10 is positioned on the element connection electrode pad 16. The element connection electrode pad 16 and the substrate connection electrode 14 are electrically and mechanically connected by a nickel pillar 20.

  The main material of the nickel pillar 20 is nickel metal, has a length of about 200 μm, a cross-sectional diameter of about 5 μm, and has a spiral structure. The joint portion with the element connection electrode pad 16 has a substantially spherical shape or dome shape. ing. Since the bonding connection between the substrate connection electrode 14 of the piezoelectric vibration element 10 and the element connection electrode pad 16 of the insulating substrate 15 through the nickel pillar 20 is achieved, compared to the bonding conduction by the conductive adhesive. The area to be bonded and fixed is significantly reduced. Therefore, the deterioration of the vibration characteristics of the piezoelectric vibration element 10 due to the nickel pillar 20 can be minimized. Note that the number of nickel pillars 20 formed between each element connection electrode pad 16 and the substrate connection electrode 14 may be one on each of the piezoelectric vibration elements 10 on the insulating substrate 15 as in this embodiment. However, a plurality of nickel pillars may be formed.

  As described above, the piezoelectric resonator element 10 is placed on one main surface by the conductive connection between the substrate connecting electrode 14 of the piezoelectric resonator element 10 and the element connecting electrode pad 16 of the insulating substrate 15 through the nickel pillar 20. On one main surface of the mounted insulating substrate 15, a substantially box-shaped metal having an opening having a flange formed around it and an annular brazing material 21 formed on the opening-side surface of the flange. The lid body 17 is disposed so that the piezoelectric vibration element 10 is accommodated in the interior space of the lid body 17, and is formed on one main surface of the brazing material 21 formed on the flange portion of the lid body 17 and the insulating substrate 15. The piezoelectric vibrator 1 is formed by joining the sealing conductor pattern 18 so that the space in which the piezoelectric vibration element 10 is housed is airtight.

Next, a method for manufacturing the piezoelectric vibrator having the above-described configuration will be described.
First, at least one nickel ball is formed on each element connection electrode pad 16 formed on one main surface of the insulating substrate 15 on which the external connection electrode terminals 19 and the sealing conductor pattern 18 are formed. Alternatively, a nickel plating layer is formed on which at least one protrusion protruding toward the piezoelectric vibration element 10 is formed. The diameter of the nickel ball is about 10 μm, and in the case of the convex portion, the convex portion having the same size as the nickel ball is formed.

  Next, on the nickel plating layer having the nickel ball or the convex portion, the piezoelectric vibration element 10 is arranged such that the substrate connecting electrode 14 formed on the piezoelectric vibration element 10 faces the convex portion of the nickel ball or the nickel plating layer. Deploy. At this time, the distance between the tip of the nickel ball on the piezoelectric vibrating element 10 side or the tip of the convex portion and the surface of the substrate connecting electrode 14 of the piezoelectric vibrating element 10 is set to 200 μm or less.

  Next, the insulating substrate 15 in which the piezoelectric vibration element 10 is arranged on the nickel ball or the nickel plating layer having the convex portion is arranged in nitrogen gas having a dew point temperature of −50 ° C., and the nickel ball or the nickel plating layer is formed. A voltage of 250 V is applied between the convex portion and the substrate connecting electrode 14. Then, the nickel pillar 20 grows in a spiral shape from the convex portion of the nickel ball or nickel plating layer toward the substrate connecting electrode 14, and the tip of the nickel pillar 20 is joined to the surface of the substrate connecting electrode 14. Thus, the element connecting electrode pad 16 and the substrate connecting electrode 14 are electrically and mechanically connected and fixed via the nickel pillar 20.

  Thereafter, an approximately box-shaped metal made of metal having an opening having a flange formed on one main surface of the insulating substrate 15 and an annular brazing material 21 formed on the opening-side surface of the flange. The lid body 17 accommodates the piezoelectric vibration element 10 in the interior space of the lid body 17, and an annular brazing material 21 is annularly formed on each side edge on one main surface of the insulating substrate 15 on the opening side surface of the flange. The insulating substrate 15 and the lid 17 are arranged so as to be in contact with the formed sealing conductor pattern 18, the brazing material 21 is heated and melted, and the space in which the piezoelectric vibration element 10 is accommodated is hermetically sealed. The piezoelectric vibrator 1 is formed by bonding.

  By using the method for manufacturing the piezoelectric vibrator 1 described above, a metallic nickel pillar that performs electrical and mechanical connection between the element connection electrode pads 16 formed on the insulating substrate 15 constituting the piezoelectric vibrator 1. Since 20 is formed by instantaneous voltage application, the manufacturing time of the piezoelectric vibrator 1 can be remarkably shortened as compared with a manufacturing method using a conductive adhesive.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the piezoelectric vibrator is illustrated and described as an example of the piezoelectric device using the present invention. However, as another piezoelectric device, the piezoelectric vibration element and the piezoelectric vibration element are disposed in the recessed space in the box-shaped container. Other than this, a piezoelectric oscillator in which an integrated circuit element including an oscillation circuit electrically connected to the piezoelectric vibration element is mounted together, a piezoelectric filter in which the piezoelectric vibration element mounted inside functions as a frequency filter, and the like In the piezoelectric device of the form, the present invention can be used for the electrical and mechanical connection fixing form of the piezoelectric vibration element mounted inside.

FIG. 1 is a schematic exploded external view showing a piezoelectric vibrator according to the present invention as an example of a piezoelectric vibrator which is one of the piezoelectric devices. FIG. 2 is an enlarged view of a part of a cross-sectional view when the piezoelectric vibrator shown in FIG. 1 is assembled and then cut along a virtual cutting line A1-A2 shown in the figure. FIG. 3 is an enlarged partial cross-sectional view showing an enlarged portion of the dotted circle B shown in FIG. FIG. 4 is a schematic partial cross-sectional view showing a conventional piezoelectric device as an example of a piezoelectric vibrator which is one of the piezoelectric devices.

Explanation of symbols

1 ... Piezoelectric vibrator (piezoelectric device)
DESCRIPTION OF SYMBOLS 10 ... Piezoelectric vibration element 11 ... Piezoelectric base plate 12 ... Excitation electrode 14 ... Substrate connection electrode 15 ... Insulating substrate 16 ... Element connection electrode pad 17 ... Cover 20 ... Nickel pillar

Claims (1)

At least a pair of element connection electrode pads are formed on the surface of the insulating substrate, a piezoelectric vibration element is disposed on the element connection electrode pad, and a pair of substrate connection electrodes formed on the surface of the piezoelectric vibration element The element connection electrode pads are electrically and mechanically connected and fixed between the opposing substrate connection electrodes and the element connection electrode pads, and the space in which the piezoelectric vibration element is mounted is covered. In a method for manufacturing a piezoelectric device that is hermetically sealed by a body ,
Forming a nickel plating layer on each of the element connection electrode pads, wherein at least one nickel ball or at least one protrusion projecting toward the piezoelectric vibration element side is formed;
The piezoelectric vibration element is disposed on the nickel ball or the nickel plating layer in such a manner that the substrate connection electrode formed on the piezoelectric vibration element faces the convex portion of the nickel ball or the nickel plating layer. Process,
A voltage is applied between the nickel ball or the convex portion of the nickel plated layer and the substrate connecting electrode, and the nickel pillar or nickel pillar extends from the convex portion of the nickel plated layer toward the substrate connecting electrode. And electrically and mechanically connecting and fixing the element connecting electrode pad and the substrate connecting electrode through the nickel pillar;
A method for manufacturing a piezoelectric device comprising:

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