JP2009200675A - Piezoelectric device and manufacturing method for the piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device, having small oscillation leak at a piezoelectric vibration piece and improved shock resistance performance. <P>SOLUTION: The piezoelectric device comprises a crystal vibration chip 20 having linking terminals 20b and 20c; a package 10 having internal terminals 11b and 11c and holding the crystal vibration chip 20; gold bumps 20d jointed to at least either the linking terminals 20b and 20c or the internal terminals 11b and 11c; and a jointing member 30 for connecting the linking terminals 20b and 20c and the internal terminals 11b and 11c via the gold bump. The device is such that the jointing member 30 is a metal bonding object of a porous structure, where powdered metals have mutually bonded. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a piezoelectric device typified by a piezoelectric vibrator and the like and a method for manufacturing the piezoelectric device.

Conventionally, a piezoelectric device typified by a piezoelectric vibrator or the like has a configuration in which a connection terminal of a piezoelectric vibrating piece and an internal terminal of a package are electrically connected via a bonding member. In general, a silicone-based conductive adhesive is used for the joining member. On the other hand, a gold film is generally formed on the connection terminal of the piezoelectric vibrating piece and the internal terminal of the package.
This silicone-based conductive adhesive is a paste-like adhesive in which silver particles called filler are mixed using a silicone resin as a base material. It is applied to the internal terminals of the package, and is heated after mounting the piezoelectric vibrating piece. Then, it hardens and electrically connects the connection terminal of the piezoelectric vibrating piece and the internal terminal of the package.

The silicone resin used in this silicone-based conductive adhesive has a characteristic that the curing speed varies depending on the surrounding metal, and the curing speed is faster when silver is present than when gold is present. have.
For this reason, in the silicone-based conductive adhesive, the periphery of the filler that is silver particles is hardened earlier than the periphery of the connection terminal of the piezoelectric vibrating piece on which the gold film is formed and the internal terminal of the package. In addition, the silicone conductive adhesive shrinks itself when cured by heating.
As a result, the silicone-based conductive adhesive moves the filler around the connection terminal and the internal terminal in the direction away from the gold coating during curing, so that the connection between the connection terminal of the piezoelectric vibrating piece and the internal terminal of the package is conducted. May interfere.

As a configuration to avoid the hindrance to conduction due to the use of this silicone-based conductive adhesive, the pad electrode (connection terminal) of the piezoelectric vibration element (piezoelectric vibration piece) and the internal terminal of the package are connected by a gold bump as a bonding member. The structure which performs is known (for example, refer patent document 1).
As another configuration, an electrode pad (connection terminal) of a surface acoustic wave element (piezoelectric vibrating piece) and an electrode pattern (internal terminal) of a substrate (package) are transferred and applied to the surface of a gold bump as a bonding member. The structure which connects with the epoxy-type electroconductive adhesive agent is known (for example, refer patent document 2).

JP 2000-232332 A JP-A-5-291864

However, since the configuration of Patent Document 1 uses gold bumps as the bonding member, the rigidity of the connecting portion between the piezoelectric vibrating piece and the package is stronger than when a silicone-based conductive adhesive is used.
As a result, the configuration of Patent Document 1 has a problem that the vibration leakage of the piezoelectric vibrating piece to the package or the like is increased, the buffering function of the connection portion against an external impact is weakened, and the impact resistance performance is lowered.

Moreover, since the heat resistance performance of an epoxy-type conductive adhesive is inferior to a silicone type conductive adhesive, the structure of patent document 2 has the problem that the heat resistance performance as a piezoelectric device falls.
Thereby, the structure of patent document 2 generate | occur | produces organic gas from the epoxy-type conductive adhesive which uses organic resin at the time of the heating of the reflow mounting to an external apparatus. For this reason, in the configuration of Patent Document 2, the degree of vacuum in the package is reduced, or gas components are condensed and attached to the piezoelectric vibrating piece.
For these reasons, the configuration of Patent Document 2 has a problem that the oscillating frequency of the piezoelectric vibrating piece changes with time and the aging performance is lowered.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A piezoelectric device according to this application example includes a piezoelectric vibrating piece having a connection terminal, a package having an internal terminal and housing the piezoelectric vibrating piece, and at least one of the connection terminal and the internal terminal. And a bonding member for connecting the connection terminal and the internal terminal via the gold bump, the bonding member having a porous structure in which powdery metals are bonded to each other. It is a body.

According to this, the piezoelectric device includes a joining member that connects the connection terminal of the piezoelectric vibrating piece and the internal terminal of the package via the gold bump. The joining member is a metal structure having a porous structure in which powdery metals are bonded to each other.
Accordingly, in the piezoelectric device, since the joining member is a metal structure having a porous structure, the rigidity of the connecting portion between the piezoelectric vibrating piece and the package is weaker than in the conventional case where the joining member is a gold bump. . Therefore, in the piezoelectric device, the vibration leakage of the piezoelectric vibrating piece to the package or the like is smaller than that of the conventional device, and the buffering function of the connection portion against an external impact is strengthened, and the impact resistance performance is improved.

In addition, since the piezoelectric device is a metal bonded body in which powdered metals are bonded to each other, the conventional bonding member is compared with the case of an epoxy-based conductive adhesive that is transferred onto the surface of a gold bump. Thus, organic gas is not easily generated.
Thereby, in the piezoelectric device, the degree of vacuum in the package is improved as compared with the related art, and adhesion of gas components to the piezoelectric vibrating piece is reduced.
Therefore, the aging performance of the piezoelectric device is improved because the oscillation frequency of the piezoelectric vibrating piece is stabilized over time.

  Application Example 2 In the piezoelectric device according to the application example described above, it is preferable that the powdered metal of the metal bonded body is spherical and bonded to each other by heating.

  According to this, in the piezoelectric device, since the powdered metal of the metal bonded body is spherical and bonded to each other by heating, the metal bonded body can be easily manufactured by a general-purpose processing method. .

  Application Example 3 A method of manufacturing a piezoelectric device according to this application example includes a piezoelectric vibrating piece having a connection terminal, a package having an internal terminal and housing the piezoelectric vibrating piece, and at least the connection terminal and the internal terminal. A method of manufacturing a piezoelectric device for connecting a gold bump bonded to any one of the above, the connection terminal and the internal terminal via the gold bump, and a bonding member having a powdered metal and a solvent, The application step of applying to the internal terminal or the gold bump bonded to the internal terminal, and the piezoelectric vibrating piece are mounted on the bonding member via the connection terminal or the gold bump bonded to the connection terminal. A mounting step, and after mounting the piezoelectric vibrating piece, the bonding member is heated to bond the powder metal to each other, and the connection terminal and the internal terminal are connected by a combined metal bonded body. It characterized by having a a coupling step of connecting through the gold bumps.

  According to this, in the piezoelectric device manufacturing method, a joining member having a powdered metal and a solvent is applied to an internal terminal or a gold bump of a package, and the piezoelectric vibrating piece is joined via the connection terminal or the gold bump. Mount on the member. And a joining member is heated, a powdery metal is mutually couple | bonded, and a connection terminal and an internal terminal are connected through a gold bump by the couple | bonded metal coupling body.

  From this, the manufacturing method of the piezoelectric device can connect the connection terminal and the internal terminal via the gold bump by a simple method of applying and heating a joining member having a powdered metal and a solvent. it can. Thereby, the manufacturing method of a piezoelectric device can provide the piezoelectric device having the operations and effects described in Application Example 1.

  Hereinafter, embodiments of a piezoelectric device and a method for manufacturing the piezoelectric device will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a configuration diagram showing a schematic configuration of a crystal resonator as an example of a piezoelectric device. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along the line AA in FIG. In the plan view, the lid (lid) portion is omitted for easy understanding, and the outer shape of the lid portion is represented by a two-dot chain line. The electrodes of the crystal vibrating piece are omitted except for some parts.
FIG. 2 is a schematic enlarged cross-sectional view of a portion B in FIG.

  As shown in FIG. 1, the crystal resonator 1 of this embodiment includes a package 10, a crystal vibrating piece 20 as a piezoelectric vibrating piece, a bonding member 30, and the like.

The package 10 includes a base part 11, a lid part 12, and a joint part 13.
For the base portion 11, a ceramic green sheet is formed, laminated and fired, and an aluminum oxide sintered body or the like is used.
Internal terminals 11 b and 11 c are formed on the bottom surface 11 a of the base portion 11. The internal terminals 11b and 11c are made of a metal film obtained by laminating each film such as nickel and gold on a metallized layer such as tungsten by plating.

Mounting terminals 11d and 11e made of the metal film are formed on the outer surface of the base portion 11. The mounting terminals 11d and 11e are connected to the internal terminals 11b and 11c by an internal wiring (not shown). The crystal resonator 1 is mounted on an external device by mounting terminals 11d and 11e.
In the base portion 11, a stepped through hole 11f is formed in the bottom surface 11a. The through hole 11f is sealed with a sealing material 40 after the lid portion 12 described later is joined. Note that a gold-germanium alloy or the like is used for the sealing material 40.

The lid portion 12 is made of a metal such as kovar, and is seam welded to a joint portion 13 made of a metal such as kovar in a state where the crystal vibrating piece 20 is accommodated in the package 10. Note that the joint portion 13 is joined to the base portion 11 by brazing or the like.
As a result, the inside of the package 10 of the crystal unit 1 is hermetically sealed. Note that the inside of the package 10 is sealed with an inert gas such as vacuum or nitrogen, helium, or argon.

A crystal vibrating piece 20 is mounted on the base portion 11 of the package 10.
The quartz crystal vibrating piece 20 is formed from a quartz wafer polished to a predetermined thickness according to the oscillation frequency or the like using a photolithography technique or the like. In the present embodiment, the crystal vibrating piece 20 is a tuning fork type crystal vibrating piece.
An excitation electrode (not shown) is formed on the crystal vibrating piece 20, and connection terminals 20 b and 20 c are extended from the excitation electrode to one main surface 20 a. The excitation electrodes and the connection terminals 20b and 20c are made of a metal film in which films such as chromium, nickel, and gold are laminated. Gold bumps 20d are joined to the connection terminals 20b and 20c.

The connection terminals 20b and 20c of the crystal vibrating piece 20 are connected to the internal terminals 11b and 11c of the base portion 11 by the bonding member 30 via the gold bumps 20d, respectively.
As shown in FIG. 2, the joining member 30 is a metal structure having a porous structure in which powdered metals are bonded to each other, and the longitudinal elastic modulus (hereinafter referred to as Young's modulus) is higher than that of the gold bump 20d due to the porous structure. It is formed to be smaller.

The bonding member 30 is a paste formed by mixing a spherical gold powder having a particle size of 0.01 μm to 0.9 μm with a solvent such as ester alcohol and a resin such as cellulose. , 11c and heated after mounting the quartz crystal vibrating piece 20, the solvent is volatilized, and the gold powders are bonded (sintered) to form a porous metal structure.
Thus, in the crystal resonator 1, the connection terminals 20b and 20c of the crystal resonator element 20 and the internal terminals 11b and 11c of the package 10 are connected by the bonding member 30 via the gold bumps 20d. Here, the porous structure means a structure in which a space exists between bonded gold (metal) powders. Details of the method for manufacturing the crystal unit 1 will be described later.

  Here, the Young's modulus of the joining member 30 is about 9.5 (GPa), which is about 1/8 of the Young's modulus of the gold bump 20d: about 78 (GPa). As a result, the rigidity of the connection portion B between the quartz crystal vibrating piece 20 and the package 10 is weak compared to the conventional configuration in which the gold bump 20d is directly joined to the internal terminals 11b and 11c. In other words, the connection part B is easily elastically deformed.

As described above, the crystal resonator 1 includes the bonding member 30 that connects the connection terminals 20b and 20c of the crystal vibrating piece 20 and the internal terminals 11b and 11c of the package via the gold bumps 20d. The bonding member 30 is a metal structure having a porous structure in which powdery gold is bonded to each other, and has a Young's modulus smaller than that of the gold bump 20d.
As a result, in the crystal resonator 1, the rigidity of the connection portion B is weaker than in the case where the conventional bonding member is the gold bump 20d. Therefore, in the crystal resonator 1, vibration leakage of the crystal vibrating piece 20 to the package 10 or the like is smaller than that in the past. In addition, the crystal unit 1 has a low rigidity of the connection portion B and is easily elastically deformed, so that the stress of the connection portion B generated by an external impact or the like is relieved. improves.

Further, since the crystal unit 1 is a metal bonded body in which the bonding member 30 is bonded with powdered gold, a conventional epoxy-based conductive adhesive in which the bonding member is transferred and applied to the surface of the gold bump 20d. Compared with the case, organic gas is less likely to be generated.
As a result, in the crystal unit 1, the degree of vacuum in the package 10 is improved as compared with the conventional case, and adhesion of gas components to the crystal vibrating piece 20 is reduced.
Therefore, in the crystal resonator 1, the aging performance is improved because the oscillation frequency of the crystal resonator element 20 is stabilized over time.

  Further, in the quartz crystal resonator 1, since the powdered gold used for the bonding member 30 is spherical and bonded to each other by heating, a metal bonded body can be easily manufactured by a general-purpose processing method. .

  In addition, the powdery metal which comprises the joining member 30 is not limited to gold | metal | money, You may use silver, copper, platinum, palladium, etc. 1 type or multiple types mixed.

Here, a manufacturing method of the crystal unit 1 will be described with reference to FIG.
FIG. 3 is an explanatory view showing a method for manufacturing the crystal unit 1.
Here, a coating process for applying the paste-like bonding member 30, a mounting process for mounting the crystal vibrating piece 20, a bonding process for connecting the crystal vibrating piece 20 to the package 10 by heating and bonding the paste-like bonding member 30. The explanation will be focused on.

  A gold bump 20d is ultrasonically bonded to the connection terminals 20b and 20c of the quartz crystal vibrating piece 20 formed by using a photolithography technique or the like from a quartz wafer that has been previously polished to a predetermined thickness according to the oscillation frequency or the like. Join. Next, the crystal vibrating piece 20 is divided from the crystal wafer into individual pieces. This operation may be performed before a mounting process described later.

[Coating process]
Next, as shown in FIG. 3A, a paste-like joining member 30 in which a gold powder, a solvent such as ester alcohol, and a resin such as cellulose is mixed is formed on the bottom surface 11 a of the base portion 11 of the package 10. The inner terminals 11b and 11c are applied with a dispenser or the like.
Here, the particle size of the gold powder of the paste-like joining member 30 is preferably in the range of 0.01 μm to 0.9 μm, and the content of the gold powder is preferably 90% by weight. The solvent content of the paste-like joining member 30 is preferably 9% by weight, and the resin content is preferably 1% by weight.

[Mounting process]
Next, as shown in FIG. 3B, the separated crystal vibrating piece 20 is mounted on the paste-like bonding member 30 through the bonded gold bumps 20d.
At this time, the gold bump 20d sinks into the paste-like joining member 30, and the paste-like joining member 30 goes around to the side wall portion 20d1.

[Bonding process]
Next, as shown in FIG. 3C, after the crystal vibrating piece 20 is mounted, the paste-like joining member 30 is heated at about 230 ° C. for about 1 hour by a heating device such as a clean oven (not shown).
As a result, the solvent of the paste-like joining member 30 is volatilized, the powdery gold is bonded to each other by sintering, and the joining member 30 (hereinafter simply referred to as “joining member 30”) as a metal bonded body made of the joined gold or the like. The internal terminals 11b and 11c and the gold bumps 20d are connected to each other.
At this time, the joining member 30 is fused to the internal terminals 11b and 11c and the gold bump 20d, and the internal terminals 11b and 11c and the gold bump 20d are firmly connected.

At this time, since the paste-like joining member 30 is not pressed, the joining member 30 has a porous structure.
In addition, since the paste-like bonding member 30 wraps around the side wall 20d1 of the gold bump 20d, the bonding member 30 wraps around the side wall 20d1 of the gold bump 20d and the internal terminals 11b and 11c. The gold bump 20d is connected.
Thus, the internal terminals 11b and 11c of the package 10 and the connection terminals 20b and 20c of the crystal vibrating piece 20 are electrically connected via the gold bumps 20d.

Next, as shown in FIG. 3C, the lid portion 12 of the package 10 is seam welded to the joint portion 13. The joining portion 13 is joined to the base portion 11 in advance by brazing or the like.
Next, after releasing the gas by annealing, the package 10 before sealing is inverted, and the sealing material 40 formed in a spherical shape is put into the through hole 11f in a vacuum or an inert gas such as in a chamber (not shown).
Next, the sealing material 40 formed in a spherical shape is melted by irradiation with a YAG (Yttrium Aluminum Garnet) laser beam, a semiconductor laser beam or the like (not shown) or heating by a heating device, and the molten sealing material 40 is melted in the through hole 11f. And the package 10 is sealed.
Through these steps, the crystal resonator 1 shown in FIG. 1 is obtained.

  As described above, in the method for manufacturing the crystal resonator 1, the paste-like bonding member 30 having powdered gold, a solvent, and a resin is applied to the internal terminals 11 b and 11 c of the package 10, and the crystal vibrating piece 20 is attached. Then, it is mounted on the paste-like bonding member 30 via the gold bump 20d. Then, the paste-like joining member 30 is heated to bond the powdery gold to each other, and the joining terminals 30 connect the internal terminals 11b and 11c to the gold bump 20d.

From this, the manufacturing method of the crystal unit 1 is made by applying a paste-like joining member 30 having powdered gold, a solvent and a resin, and heating the joining member 30 with a porous structure. It can be a metal bond.
Thereby, the manufacturing method of the crystal unit 1 can provide the crystal unit 1 having the small vibration leakage of the crystal vibrating piece 20 and improved impact resistance as described above.

  Further, in the manufacturing method of the crystal unit 1, the internal terminals 11b and 11c are connected to the gold bump 20d in a state where the bonding member 30 has wraps around to the side wall 20d1 of the gold bump 20d. From this, the manufacturing method of the crystal unit 1 can make the contact range between the bonding member 30 and the gold bump 20d wider than the case where there is no wraparound, and the connection between the internal terminals 11b and 11c and the gold bump 20d. Strength can be improved.

Further, in the manufacturing method of the crystal unit 1, since the internal terminals 11b and 11c and the gold bump 20d are connected by the bonding member 30 that is a metal combined body, organic gas is hardly generated. Thereby, the manufacturing method of the crystal unit 1 improves the degree of vacuum in the package 10 and reduces the adhesion of the gas component to the crystal vibrating piece 20.
Accordingly, the method for manufacturing the crystal resonator 1 can provide the crystal resonator 1 with improved aging performance because the oscillation frequency of the crystal resonator element 20 is stabilized over time.

In the present embodiment, the gold bump 20d is bonded to the connection terminals 20b and 20c of the crystal vibrating piece 20, but the present invention is not limited to this. The gold bump 20d may be bonded to the internal terminals 11b and 11c of the package 10, or may be bonded to both the connection terminals 20b and 20c and the internal terminals 11b and 11c.
That is, the gold bump 20d only needs to be bonded to at least one of the connection terminals 20b and 20c and the internal terminals 11b and 11c.
When the gold bump 20d is bonded to the internal terminals 11b and 11c of the package 10, the paste-like bonding member 30 is applied to the gold bump 20d.

In addition, the content of the gold powder, the solvent content, and the resin content of the paste-like joining member 30 of the present embodiment are not limited to the above-described numerical values, and the application state of the paste-like joining member 30 and the joining You may set suitably according to the coupling strength of the member 30, etc.
The proportion of each content of the paste-like joining member 30 is, for example, 88 to 93% by weight of gold powder, 6 to 11% by weight of solvent, and 1 to 4% by weight of resin. It may be set within the range.

Further, the temperature at which the paste-like joining member 30 is heated is not limited to about 230 ° C., but the joining strength of the joining member 30, the connection strength between the gold bump 20d of the joining member 30 and the internal terminals 11b and 11c, and the like. Accordingly, it may be set appropriately.
You may set the temperature which heats the paste-like joining member 30 within the range of 200 to 300 degreeC, for example.

In the present embodiment, the tuning-fork type crystal vibrating piece 20 has been described as an example of the piezoelectric vibrating piece. However, the present invention is not limited to this, and an AT-cut quartz vibrating piece, a surface acoustic wave vibrating piece, or the like may be used. Further, as a piezoelectric material other than quartz, lithium tantalate, lithium niobate, or the like may be used.
Further, although the quartz resonator 1 has been described as an example of the piezoelectric device, the present invention is not limited to this, and a quartz oscillator, a surface acoustic wave resonator, a frequency filter, or the like may be used.

The block diagram which shows schematic structure of the crystal oscillator of this embodiment. The model expanded sectional view of the principal part of the crystal oscillator of this embodiment. Explanatory drawing which shows the manufacturing method of the crystal oscillator of this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Crystal resonator as a piezoelectric device, 10 ... Package, 11b, 11c ... Internal terminal, 20 ... Crystal vibrating piece as a piezoelectric vibrating piece, 20b, 20c ... Connection terminal, 20d ... Gold bump, 30 ... Joining member.

Claims (3)

A piezoelectric vibrating piece having a connection terminal; a package having an internal terminal and housing the piezoelectric vibrating piece; a gold bump bonded to at least one of the connection terminal and the internal terminal; the connection terminal and the internal A bonding member for connecting the terminal via the gold bump,
2. The piezoelectric device according to claim 1, wherein the bonding member is a porous metal bonded body in which powdery metals are bonded to each other.   2. The piezoelectric device according to claim 1, wherein the metal bonded body has a spherical shape of the powdered metal and is bonded to each other by heating. 3. A piezoelectric vibrating piece having a connection terminal; a package having an internal terminal and housing the piezoelectric vibrating piece; a gold bump bonded to at least one of the connection terminal and the internal terminal; the connection terminal and the internal A method of manufacturing a piezoelectric device that connects a terminal to the gold bump,
An application step of applying a bonding member having a powdered metal and a solvent to the internal terminal or the gold bump bonded to the internal terminal,
A mounting step of mounting the piezoelectric vibrating piece on the bonding member via the connection terminal or the gold bump bonded to the connection terminal;
After mounting the piezoelectric vibrating piece, the bonding member is heated to bond the powdery metals to each other, and the connection terminal and the internal terminal are connected via the gold bumps by the combined metal bonded body And a method of manufacturing the piezoelectric device.

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