JP2006211089A - Piezoelectric vibration device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibration device compatible with microminiaturization, the electric characteristic of which is stabilized and wherein practical mechanical joining can be carried out. <P>SOLUTION: The surface mount type crystal vibrator comprises: a crystal diaphragm (piezoelectric diaphragm)1; a package 2 for housing the crystal diaphragm; and a lid 3 for hermitically sealing the package. The crystal diaphragm 2 is joined with connection electrodes 12, 13 of the ceramic package by a metallic minute particle paste joining material S. The metallic minute particle paste joining material S contains metallic minute particles the dispersing agent existing on the surface of which is removed by heating and a binder resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric vibration device such as a crystal resonator used for mobile radio equipment and the like, and more particularly to electromechanical joining of piezoelectric vibration plates.

  Currently used piezoelectric vibrators have a configuration in which excitation electrodes are formed on the front and back surfaces of a piezoelectric diaphragm. For example, a thickness-shear vibrator using an AT-cut quartz diaphragm is often used. As is well known, the AT-cut quartz diaphragm can be made to correspond to a high frequency, the resonance frequency is determined by the plate thickness, and the plate thickness and the resonance frequency are inversely proportional. Therefore, in order to cope with the high frequency required in recent mobile radio equipment and the like, an ultra-thin piezoelectric diaphragm utilizing a high-level polishing technique is used.

  When mounting such an extremely thin piezoelectric diaphragm on a package, for example, a silicone resin-based bonding material to which a conductive filler is added is used. Such a silicone resin bonding material has a relatively soft hardness after curing, and when used for conductive bonding with a package, it effectively reduces the impact caused by external factors and contributes to improving the shock resistance of the piezoelectric vibration device. It was. For example, WO01 / 67600 (Patent Document 1) is an invention made by paying attention to the impact resistance of such a silicone-based resin, and discloses a configuration in which a crystal diaphragm and a package are bonded by a silicone-based resin bonding material. Has been.

  However, due to miniaturization of electronic equipment using piezoelectric vibration devices, the piezoelectric vibration devices are also required to be ultra-miniaturized, and therefore the bonding area between the piezoelectric vibration plate and the package is extremely small. Such narrowing of the joining area has a problem that the electrical performance is lowered due to the so-called resin-rich problem that the mechanical strength is lowered and the resin ratio is increased. In general, in order to ensure mechanical bonding strength, the resin ratio is increased and the conductive filler is relatively decreased. In this case, the resistance value of the bonding material is high, and there is a problem that the mechanical bonding property and the electric bonding property are in a trade-off relationship in the resin adhesive to which the conductive filler is added. In particular, when the resin becomes rich, there is a problem that the resistance value increases in a high temperature environment. This is thought to be because the resin expands due to an increase in the environmental temperature and the contact opportunity between the conductive fillers inside decreases, and such fluctuations in resistance value deteriorate the characteristics of the piezoelectric vibration device and do not meet the required specifications. There was a thing.

  In order to solve such a problem, there is a method of using metal bumps such as gold or solder as a bonding material as a method for performing reliable conductive bonding in a minute region. In this method, the extraction electrode of the piezoelectric diaphragm and the connection electrode of the package are bonded to each other via metal bumps, and electromechanical bonding can be performed in a minute region. For example, Japanese Patent Application Laid-Open No. 2000-68777 (Patent Document 2) discloses a configuration in which metal bumps are formed on connection electrodes and an extraction electrode of a piezoelectric diaphragm is electromechanically joined by ultrasonic welding.

  However, the structure using such metal bumps has a low shock-absorbing property because mechanically strong bonding is performed as described above, and the influence of thermal distortion due to the difference between the external impact and the temperature expansion coefficient with the peripheral members is low. In some cases, the characteristics of the piezoelectric vibration device deteriorate.

In recent years, attention has been paid to low-temperature sintering (fusion) properties of metal fine particles and denseness (conductivity) after sintering, and conductive pastes using the metal fine particles have been developed. For example, Japanese Patent Application Laid-Open No. 2001-225180 (Patent Document 3) discloses a method of conducting conductive bonding using a paste in which metal fine particles whose surfaces are coated with an organic substance are dispersed in an organic solvent. ing.
WO01 / 67600 JP 2000-68777 A JP 2001-225180 A

  The present invention has been made in view of such a point, and the object of the present invention is to stabilize the electrical characteristics and to perform practical mechanical joining in joining the piezoelectric diaphragm and the package. An object of the present invention is to provide a piezoelectric vibration device that is compatible with ultra-miniaturization.

  As a result of intensive studies on the bonding of the piezoelectric diaphragm to the package (base), the present inventor intends to apply the conductive paste using the metal fine particles as described above to the bonding of the piezoelectric diaphragm and the package (base). The above problems were solved by the following configuration.

That is, as shown in claim 1, at least one surface is provided with an excitation electrode and an extraction electrode for leading the excitation electrode to the outside, and the piezoelectric oscillation plate is hermetically stored, and the extraction electrode and the conductive electrode are electrically conductive. A piezoelectric vibration device comprising a package having a connection electrode to be bonded, and an opening portion of the package and a lid to be airtightly bonded, wherein the lead electrode and the connection electrode of the piezoelectric vibration plate have an average particle size of 1 The structure is characterized in that the surface is coated with an organic coating on the surface and is bonded by a metal fine particle paste bonding material in which metal fine particles from which the organic coating is removed by heating are dispersed in an organic solvent. .

The present invention can also be applied to a piezoelectric vibration device with a lead terminal. According to a second aspect of the present invention, there is provided a piezoelectric diaphragm having at least one surface formed with an excitation electrode and an extraction electrode for leading the excitation electrode to the outside, and a plurality of independent electrodes that are conductively joined to the extraction electrode of the piezoelectric diaphragm. A piezoelectric vibration device comprising a base through which a lead terminal is formed and a cap that is airtightly connected to the base and hermetically seals the piezoelectric vibration plate, wherein the lead electrode of the piezoelectric vibration plate and the lead terminal are: The average particle diameter is 1 to 100 nm, the surface is coated with an organic coating, and the metal fine particles from which the organic coating is removed by heating are bonded by a metal fine particle paste bonding material dispersed in an organic solvent. The configuration is as follows. The lead terminal is a conductive terminal made of, for example, a metal wire, and a metal film such as gold, silver, or nickel is preferably formed on the surface thereof.

The present invention can also be applied to the case of bonding not only the piezoelectric diaphragm but also other electronic component elements to the package. That is, as shown in claim 3, a piezoelectric diaphragm in which an excitation electrode and an extraction electrode for leading the excitation electrode to the outside are formed on at least one surface, an electronic component element constituting a circuit with the piezoelectric diaphragm, The piezoelectric diaphragm and the electronic component element are hermetically housed, and include a package having connection electrodes that are conductively joined to the extraction electrode and the electrode of the electronic component element, respectively, and a lid that is hermetically joined to the opening of the package. A piezoelectric vibration device, wherein each of the conductive junctions has an average particle diameter of 1 to 100 nm, a surface is coated with an organic coating, and the metal fine particles from which the organic coating is removed by heating are placed in an organic solvent. It is a structure characterized in that the contact is made with a dispersed metal fine particle paste bonding material.

In this case, the bonding material may be applied to a plurality of locations at once, and the electronic component element and the piezoelectric vibration plate may be sequentially mounted to perform heat bonding. In addition, after some elements (piezoelectric vibration devices and electronic component elements) are first heat-bonded with the metal fine particle paste bonding material, the other fine elements are coated with the metal fine particle paste bonding material and heat bonded. Good.

In addition, in the structure of claim 1 or claim 3, when the rectangular piezoelectric diaphragm is cantilevered at one end in the long side direction, an auxiliary support material (pillow material) that ensures horizontal mounting of the piezoelectric diaphragm is the same. Although it may be formed at the other end, such an auxiliary support material may be formed by the metal fine particle paste bonding material disclosed in the present invention. The auxiliary support member may be formed by applying a metal fine particle paste bonding material to a position corresponding to the other end of the piezoelectric diaphragm, for example, a part of the package or the upper part of the electronic component element, and solidifying by heating. It is preferable to apply a metal fine particle paste bonding material containing a binder resin to such an auxiliary support material because it has a buffering function.

The metal fine particles contained in the above-mentioned metal fine particle paste bonding material can be exemplified by metal materials such as gold, silver, copper, nickel, titanium, etc. The fine shape is spherical or elliptical or polygonal, etc. It is preferable that the structure has multiple surfaces or curvature surfaces. This is because when the surface is multi-faced or has a curvature, primitive diffusion, that is, fusion occurs uniformly in each direction, and a preferable fusion state can be obtained at the time of joining.

  As disclosed in Patent Document 3, the smaller the diameter of the metal fine particles, the easier the fusion proceeds, but it is necessary to make the particles finer than necessary in consideration of the work of forming the organic coating on the surface of the metal fine particles. There is no need to have a diameter of 1 to 100 nm. When the thickness is 1 nm or less, the fusion between the metal fine particles is intense, so that handling becomes difficult. When the thickness is 100 nm or more, the fusion property between the metal fine particles is deteriorated. Note that, when the conductive bonding region is narrowed, it is necessary that reliable electrical bonding is performed in a minute region, and thus a smaller particle diameter is preferable. Depending on the type of metal and organic coating, metal fine particles with an average particle diameter of 2 to 30 nm can be used for bonding of piezoelectric vibration devices in the handling of metal fine particles on which an organic coating is formed and bonding properties during heating ( The balance of securing the bonding property in a minute region is preferable.

  In the metal fine particle paste bonding material used in the present invention, an organic coating is formed on the surface of the metal fine particles, and the organic coating plays a role as a dispersant for suppressing the fusion of the metal fine particles. The metal fine particles are covered. In addition, the organic coating is configured to be removed by transpiration or the like by placing it in a predetermined temperature environment, and by removing the organic coating, fusion of the metal fine particles that has been suppressed occurs. Accelerated. Further, the fusion of the metal fine particles also occurs between the extraction electrode of the piezoelectric diaphragm and the connection electrode, and finally, the electrodes are fused and agglomerated and the metal fine particles are agglomerated to form metal-to-metal bonding. Therefore, strong conductive bonding can be performed in a minute region, and highly reliable bonding can be performed without interference between the plurality of electrodes formed in the miniaturized piezoelectric vibration device.

The metal fine particle paste bonding material is configured to be dispersed in an organic solvent, and the wettability of the paste can be adjusted by selecting the viscosity, thixotropy, and the like of the solvent. Further, the organic coating film is removed by transpiration or the like by heating, and a favorable metal-to-metal bonding state can be obtained by using a material that is also removed by heating for the organic solvent. Further, as described later, the binder resin may remain as a bonding material after curing by adding a binder resin instead of the organic solvent or in addition to the organic solvent, thereby improving the buffer performance.

Since the metal fine particle paste bonding material can obtain metal-to-metal bonding with the metal fine particles after being fused as described above, it is bonded compared to conventional mechanical bonding with resin using a resin bonding material to which a conductive filler is added. The thickness occupied by the material can be made extremely thin, and the thickness control is relatively easy.

Accordingly, a plurality of excitation electrodes and extraction electrodes corresponding to the excitation electrodes are formed on the piezoelectric diaphragm, and at least one of the extraction electrodes and the connection electrode are connected to the metal fine particle paste. By adopting the configuration in which the bonding material is bonded to the bonding material, in the region bonded by the metal fine particle paste bonding material, the mechanical bonding of the piezoelectric diaphragm can be stabilized and the conductive bonding having a small electric resistance can be performed.

Furthermore, as shown in claim 5, in each of the above-described configurations, the piezoelectric diaphragm is formed with a plurality of excitation electrodes and extraction electrodes corresponding to the excitation electrodes, and the connection between the extraction electrodes and the connection electrodes is performed as described above. It is good also as a structure joined by the metal fine particle paste joining material.

According to the configuration of the fifth aspect, since the plurality of connections of the piezoelectric diaphragm, the extraction electrode, and the connection electrode are bonded by the metal fine particle paste bonding material, the metal fine particle paste bonding material is supplied to the bonding region. The work can be easily performed, and the mechanical bonding of the piezoelectric diaphragm can be made more stable and the conductive bonding can be performed with lower electric resistance.

  The present invention also discloses combining the joining by the metal fine particle paste joining material with another joining method when there are joining points of a plurality of extraction electrodes and connection electrodes. For example, as shown in claim 6, a plurality of excitation electrodes and extraction electrodes corresponding to the excitation electrodes are formed on the piezoelectric diaphragm, and at least one of the excitation electrodes and the connection electrode are connected to the metal fine particle paste. It is good also as a structure characterized by joining by the joining material and connecting the other excitation electrode and connection electrode by the metal-metal joining by a metal bump.

  Bonding by metal bumps is a configuration in which bumps (small metal blocks) are interposed between the electrodes and both electrodes are conductively bonded by inter-metal bonding, and strong mechanical bonding and electrical bonding can be performed in a small area. . However, as described in the background art section, the buffering performance is low, and thermal distortion due to environmental temperature fluctuations cannot be absorbed. According to the sixth aspect of the present invention, by combining the metal fine particle paste bonding material having a buffering property and the bonding by the metal bump as described above, the electromechanical bonding property is improved, and the piezoelectric vibration device having a good buffering property. Can be obtained.

According to a seventh aspect of the present invention, in each of the above-described configurations, the metal fine particles of the metal fine particle paste bonding material and the metal film on the bonding surface of the extraction electrode and the connection electrode are the same kind of metal. It is good.

By making the metal fine particles the same metal as the metal film on the bonding surface of the extraction electrode and the connection electrode, it is possible to promote the fusion property of both at the time of heat bonding, and to improve the bonding property of both. In addition, since the thermal expansion coefficients of both are equal after bonding, it is possible to eliminate a damage accident in the bonding region due to the atmospheric temperature fluctuation after bonding.

Furthermore, as shown in claim 8, in each of the above-described configurations, the metal fine particle paste bonding material includes a plurality of layers, and a part of the layer is a metal fine particle paste using copper as metal fine particles. It is good also as a structure.

Copper has excellent ductility and high heat buffering performance. Therefore, by using copper having a high thermal buffering property for the partial layer of the metal fine particles, even if the atmospheric temperature after the bonding varies, the damage of the bonding region can be eliminated by the buffering performance by the copper.

Further, according to the present invention, as shown in claim 9, the metal fine particle paste bonding material includes a binder resin for mechanically bonding the extraction electrode and the connection electrode of the piezoelectric diaphragm. The piezoelectric vibration device according to any one of Items 1 to 8 is also disclosed. Such a configuration can be applied to bonding of piezoelectric diaphragms, bonding of electronic component elements, or the above-described auxiliary support material.

In the metal fine particle paste bonding material containing the binder resin, the metal fine particles are dispersed in the binder resin, and the metal fine particles are fused together by heating. The state in which the particles are fused is likely to be a state in which the particles are connected in a chain form. Accordingly, since the chain-like particles are present in the resin, the bonded state is mechanically buffered, and practical electrical continuity can be obtained.

  By the way, the present invention also discloses another method for controlling the fusing property of metal fine particles. For example, claim 10 discloses the piezoelectric vibration device according to any one of claims 1 to 9, wherein a reducing agent for the metal fine particles is added to the metal fine particle paste bonding material. As an example of the reducing agent, as shown in claim 11, palladium added in an amount of 1 to 10% by weight to the metal fine particle paste bonding material is exemplified.

  Examples of the metal fine particles include metal materials such as gold, silver, copper, nickel, and titanium. By adding a reducing agent to these metals, the fusion property can be improved. Palladium functions as a reducing agent for these metals. That is, the oxide film that prevents fusion of the surface of each metal fine particle is removed, and the surface of the metal fine particle is activated to improve the fusion property.

  In addition, the activity as a reducing agent can be increased by making the particle size of palladium minute, and as shown in claim 12, the average particle size of palladium is preferably 1 to 60 nm. By reducing the average particle size to 60 nm or less, the activity as a reducing agent can be enhanced, and by setting the average particle size to 1 nm or more, problems such as too high fusibility are suppressed, and handling thereof is made practical. Can do.

  According to the present invention, it is possible to obtain a piezoelectric vibration device corresponding to ultra-miniaturization, which has stable electrical characteristics and can perform practical mechanical joining.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
A first embodiment of the present invention will be described with reference to FIGS. 1 and 2 by taking a surface-mounted crystal resonator as an example. FIG. 1 is a sectional view showing the present embodiment, and FIG. 2 is a plan view showing the present embodiment. The surface-mounted crystal resonator includes a crystal diaphragm (piezoelectric diaphragm) 1, a package 2 that houses the crystal diaphragm, and a lid 3 that hermetically seals the package.

  The quartz crystal plate 2 is a flat and rectangular AT-cut crystal plate, and excitation electrodes 21 and 31 (31 is not shown) are formed on the front and back surfaces thereof. Each of the excitation electrodes 21 and 31 has a rectangular shape, and extraction electrodes 21a and 31a (31a not shown) are drawn from each excitation electrode to the outer edge at one end in the long side direction of the quartz crystal vibration plate. The quartz crystal plate 2 can be obtained by polishing a large wafer to a predetermined thickness before electrode formation and then dividing it into a large number of pieces, or dividing it into a large number of pieces and then individually polishing them. Can do. Dividing and cutting out from the wafer may be performed using a wire saw, a dicing method, or a laser beam. Each electrode material formed on the quartz diaphragm has a configuration in which, for example, chromium is formed in contact with the quartz diaphragm, and gold or silver is formed thereon.

  The package 1 on which the crystal diaphragm 2 is mounted is a ceramic package provided with electrode wiring. The package is made of alumina or the like and has a box-shaped configuration with an open top, and connection electrodes 12 and 13 are formed at the stepped portion formed inside the package. The connection electrodes 12 and 13 are electrically connected to external connection electrodes 14 and 15 formed on the external bottom surface of the package 1 through connection electrodes (not shown). Each electrode of the package 1 and the metal film layer 11 in the opening are configured such that a thick film layer of tungsten or molybdenum is formed on the ceramic surface, a nickel layer is formed on the upper surface, and a gold layer is further plated thereon. It is formed by a technique.

The crystal diaphragm 2 is bonded to the connection electrodes 12 and 13 of the ceramic package by the metal fine particle paste bonding material S. In the present embodiment, as the metal fine particle paste bonding material, a binder resin containing a nanopaste (trade name) manufactured by Harima Kasei Co., Ltd. in a binder resin is used. The metal fine particles used for the bonding material are silver metal fine particles having an average particle diameter of 7 μm. Further, an organic coating (dispersing agent) that is removed by heating is formed on the surface of the silver metal fine particles, and the metal fine particle paste bonding material is a heat in which the metal fine particles having the organic coating are made of an epoxy resin. The structure is dispersed in a curable organic solvent (binder).

In the present embodiment, the curing temperature of the binder resin and the fusion temperature of the metal fine particles are adjusted to be substantially the same. For example, when these temperatures are set to about 200 ° C., the heating is performed to the temperature. By doing so, electromechanical joining can be performed smoothly simultaneously.

An appropriate amount of the metal fine particle paste bonding material S is applied on the connection electrodes 12 and 13 in advance, and mounted so that the extraction electrodes 21a and 31a of the quartz crystal plate overlap the upper portions thereof. You may apply | coat further on the extraction electrodes 21a and 31a as needed. In this state, heating is performed to cure the metal fine particle paste bonding material and fuse the internal metal fine particles. This heating may be performed in a vacuum atmosphere or an inert gas atmosphere such as nitrogen gas. As a result, the organic coating formed on the surface of the metal fine particles is melted, and mutual fusion (sintering) with adjacent metal fine particles occurs. Intermetallic bonding is performed between the metal films used. In this embodiment, since the organic solvent remains after being thermally cured, auxiliary bonding can be performed.

  By the way, gold is used for the metal fine particles, and gold is also used for the surface metal of the connection electrode and the extraction electrode, so that the metal-to-metal bonding can be smoothly performed by fusing the same kind of metal to each other, and the bonding property is improved. improves. A combination of other similar metals may be used.

  After the joining is completed, necessary stabilization work and cleaning work are performed, the lid 3 and the metal film layer 11 are joined in a vacuum atmosphere or an inert gas atmosphere, and the package is hermetically sealed. As a hermetic sealing method, known seam welding, beam welding, or joining using a brazing material may be used.

  The present invention is not limited to the above-described embodiments, and can be applied to various modified examples such as bonding of piezoelectric diaphragms or bonding of electronic component elements. FIG. 3 is a cross-sectional view showing a second embodiment of the surface-mount type crystal resonator, and shows a both-end supported structure in which the crystal diaphragm 2 is held at both ends in the long side direction. In addition, about the same structure part as 1st Embodiment, while using the same number, it demonstrates and a part of description is omitted.

  The quartz diaphragm 2 is a flat and rectangular AT-cut quartz diaphragm, and excitation electrodes (not shown) are formed on the front and back surfaces thereof. Each excitation electrode has a rectangular shape, and the excitation electrode formed on the surface of the crystal diaphragm is drawn out to the outer edge of one end in the long side of the crystal diaphragm by the extraction electrode, and is formed on the back surface of the crystal diaphragm Is drawn out to the outer edge of the other end in the long side direction of the quartz crystal diaphragm by a lead electrode. Each electrode material formed on the quartz diaphragm has a configuration in which, for example, chromium is formed in contact with the quartz diaphragm and gold or silver is formed on the top thereof.

  The package 1 on which the crystal diaphragm 2 is mounted is a ceramic package provided with electrode wiring. The package is made of alumina or the like and has a box-shaped configuration with an opening at the top, and connection electrodes 16 and 17 are formed in stepped portions formed inside the package and facing each other in the long side direction. The connection electrodes 16 and 17 are electrically connected to external connection electrodes 18 and 19 formed on the outer bottom surface of the package via connection electrodes (not shown). Each electrode of the package and the structure of the metal film layer 11 at the opening are formed by a method in which a thick film layer of tungsten or molybdenum is formed on the ceramic surface, a nickel layer is formed on the upper surface, and a gold layer is further plated thereon. It is formed by.

  In the present embodiment, one extraction electrode of the crystal diaphragm 2 is conductively bonded by the metal fine particle paste bonding material S, and the other is bonded by the metal bump B. Therefore, one or a plurality of metal bumps are formed in advance on the connection electrode 17 that is conductively bonded with the metal bumps. The metal bump is made of, for example, gold, and may be formed by a method such as forming a wire bump using a wire bonding technique or by laminating a gold layer.

  Further, the metal fine particle paste bonding material S has a configuration in which a reducing agent is added. More specifically, a metal fine particle paste bonding material in which silver is used for the metal fine particles and palladium is added as a reducing agent in a proportion of 3% by weight is used. The palladium has an average particle size as small as 30 nm, can increase the activity during fusion, and can improve the bonding strength during heat bonding.

  In addition, it is preferable to select a particle size of about 1 to 60 nm because a balance between bondability and handling is obtained. Further, the addition amount is preferably 1 to 10% by weight, and if it is 1% by weight or less, the ability as a reducing agent is lowered, and the conductivity may be lowered. On the other hand, when the amount is 10% by weight or more, the reducing performance becomes excessive, and the handling may be troublesome, such as early curing of the bonding agent or high viscosity, resulting in inconvenience when supplying the bonding material.

  Then, an appropriate amount of the metal fine particle paste bonding material S is applied on the connection electrode 16 in advance, and the extraction electrode of the crystal diaphragm is mounted on the connection electrode 16 and 17 so as to overlap the upper part. In this state, first, an ultrasonic wave is applied to the crystal diaphragm on the connection electrode 17 side to fuse the metal bumps and conduct conductive bonding. The application of ultrasonic waves may be performed using a known ultrasonic bonding machine.

Thereafter, heating is performed to cure the metal fine particle paste bonding material and fuse the internal metal fine particles. This heating may be performed in a vacuum atmosphere or an inert gas atmosphere such as nitrogen gas. As a result, the organic coating formed on the surface of the metal fine particles is melted and mutual fusion (sintering) with adjacent metal fine particles occurs, and this accelerates the metal fine particles in combination with the effect of suppressing oxidation by the reducing agent. Metal-to-metal bonding is performed between the metal films used for the intermediate electrode and the excitation electrode and the connection electrode. In the present embodiment, since a metal fine particle paste bonding material containing a binder resin is used, auxiliary bonding can be performed. Moreover, since various distortions can be relieved by the buffering action of the resin against the strong bonding by the metal bumps, the characteristics of the surface-mount type crystal resonator can be kept good.

  A third embodiment of the present invention will be described with reference to FIG. 4 using a surface-mount crystal oscillator as an example. FIG. 4 is an internal cross-sectional view showing a surface-mounted crystal oscillator, in which a ceramic package 4 on which necessary internal wiring is formed is provided with a crystal diaphragm and an integrated circuit element (electronic) constituting the crystal diaphragm 2 and the oscillation circuit. The component element) P is housed.

The ceramic package 4 has a region 4a for storing the integrated circuit element P and a region 4b for storing the crystal diaphragm 2 above the region, and these regions are spatially connected. A plurality of microelectrode pads 44 are formed at the bottom of the region 4a. These microelectrode pads 44 are for conductively bonding the integrated circuit element P and are appropriately wired in the ceramic package. In the region 4b, connection electrodes 42 and 43 (43 is not shown) are formed on the stepped portion. In addition, a metal film layer 41 is formed on the upper surface of the bank portion in a circumferential shape in the opening of the package.

  The crystal diaphragm 2 is a flat and rectangular AT-cut crystal diaphragm similar to the configuration shown in the first embodiment, and excitation electrodes 21 and 31 (31 is not shown) are formed on the front and back surfaces thereof. ing. Each of the excitation electrodes 21 and 31 has a rectangular shape, and extraction electrodes 21a and 31a (31a not shown) are drawn from each excitation electrode to the outer edge at one end in the long side direction of the quartz crystal vibration plate.

  The integrated circuit element P is a rectangular parallelepiped chip type, and a plurality of extraction electrodes (not shown) are formed on the lower surface. The lead electrodes and the microelectrode pads of the ceramic package are conductively joined, so that a part of the lead electrodes is electrically connected to the crystal diaphragm 2 by wiring formed in the package, and an oscillation circuit and the like are formed together with the crystal diaphragm 2. Is done.

  When bonding the integrated circuit element P, first, the metal fine particle paste bonding material S is applied on the microelectrode pads 44, and the integrated circuit element P is mounted. And the electromechanical joining is performed by heating the said metal fine particle paste joining material S to predetermined temperature. Note that the metal fine particle paste bonding material used here may contain a thermosetting binder resin such as an epoxy resin. In addition to the epoxy resin, a silicone resin, a urethane resin, or a polyimide resin can be used as the binder resin. In particular, since silicone resins and urethane resins are relatively excellent in flexibility, buffer performance can be obtained, which contributes to an improvement in impact resistance as a piezoelectric vibration device.

  In addition, in the bonding of the integrated circuit element P, a metal fine particle paste bonding material not containing a binder resin may be used, and in the bonding of the crystal diaphragm, a material containing a binder resin may be used. The reverse combination may be applied.

  Further, the heat bonding of the integrated circuit element P and the crystal diaphragm 2 with the metal fine particle paste bonding material may be performed simultaneously. That is, a metal fine particle paste bonding material is applied on the microelectrode pad 44 and the connection electrodes 42 and 43, the integrated circuit element P and the crystal diaphragm 2 are mounted on the respective electrodes, and electromechanical bonding is performed by batch heating. May be.

  In FIG. 4, an auxiliary support material S <b> 1 is formed on the upper surface of the integrated circuit element P. This auxiliary support material S1 is disposed at a position corresponding to the side opposite to the support side of the crystal diaphragm, and may be a buffer support made of silicone resin previously formed on the integrated circuit element. A metal fine particle paste bonding material may be used. In this case, after the integrated circuit element P is mounted on the microelectrode pad 44, a metal fine particle paste bonding material may be applied to a predetermined position on the upper surface of the integrated circuit element P and cured by heating at the time of bonding the integrated circuit element.

  After the joining is completed, necessary stabilization work and cleaning work are performed, the lid 3 and the metal film layer 11 are joined in a vacuum atmosphere or an inert gas atmosphere, and the package is hermetically sealed. As a hermetic sealing method, known seam welding, beam welding, or joining using a brazing material may be used.

  The present invention can also be applied to a configuration in which a piezoelectric diaphragm is joined to a base having lead terminals. The fourth embodiment shows an example applied to a base having this lead terminal, and will be described with reference to FIGS. 5 (a) and 5 (b). 5 is a diagram showing an example in which a crystal diaphragm is joined to a base having a lead terminal with a metal fine particle paste joining material, FIG. 5 (a) is a view from the front, and FIG. 5 (b) is a view from the side. It is.

  The base 6 has a structure in which an insulating glass 62 is filled in a shell 61 whose central portion penetrates vertically, and linear lead terminals 63 and 64 are vertically penetrated through the glass 62. As a result, the inner lead portions 631 and 641 protrude from the upper surface of the base. The inner lead portion may be flattened at the contact portion with the crystal diaphragm, such as processing into a flat plate shape so as to make a surface contact with the crystal diaphragm described later.

The crystal diaphragm 5 in contact with the base is a tuning-fork type quartz diaphragm that vibrates in a bending mode. Although not shown, a pair of excitation electrodes are formed on the front and back surfaces and side surfaces of the tuning fork section, and are drawn out to one surface of the base section. Yes.

The metal fine particle paste bonding material S is applied to the joint portion of the crystal diaphragm 5 with the base or the inner lead portions 631 and 641 of the base, and the two are brought into contact with each other by heat bonding. In this configuration, since the lead terminal has a buffering function, the buffering action by the binder resin is not so required. Therefore, the metal fine particle paste bonding material used for the bonding may not contain a binder resin.

  Although not shown, after the crystal diaphragm 6 and the lead terminal are conductively joined, the quartz diaphragm can be covered and hermetically sealed by press-fitting a bottomed cylindrical cap into the base. .

  In addition, you may perform application | coating to the connection electrode etc. of a metal fine particle paste bonding material by the inkjet printing method. The ink jet printing method, for example, is a printing method in which a predetermined pattern is drawn by minutely ejecting ink in a nozzle by mechanical vibration by a piezoelectric element, but a liquid suitable for minute ejection such as lowering the viscosity of a bonding material. It is necessary to adjust the characteristics. When an ink jet printing method is used, there is an advantage that a desired coating pattern can be made fine and applied at high speed. In particular, when the bonding material is supplied to the connection electrode or the like on the ceramic package described in the first to third embodiments, the ink jet printing method is suitable.

  In each of the above embodiments, a surface-mount type crystal resonator using an AT-cut crystal diaphragm is illustrated, but it can be applied to a crystal filter element. In addition to the AT-cut quartz diaphragm, the piezoelectric diaphragm may use other piezoelectric materials such as an SC-cut quartz diaphragm and a piezoelectric ceramic diaphragm.

  The metal fine particles used for the metal fine particle paste bonding material used in each embodiment are exemplified by gold, but single fine particles such as silver and copper may be used. A plurality of metal fine particles may be used for the paste layer. In addition, when copper is used for the metal fine particles, the heat buffering performance can be increased due to the high ductility of copper.

The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  It can be applied to mass production of piezoelectric vibration devices such as crystal resonators, crystal filters, and crystal oscillators.

1 is an internal cross-sectional view showing a first embodiment according to the present invention. The top view which shows 1st Embodiment by this invention. The internal sectional view showing the 2nd embodiment by the present invention. The internal sectional view showing the 3rd embodiment by the present invention. The figure which shows 4th Embodiment by this invention.

Explanation of symbols

Ceramic package 2, 5 Crystal diaphragm (piezoelectric diaphragm)
3 Lid S, S1 Metal fine particle paste bonding material

Claims (12)

A piezoelectric diaphragm in which an excitation electrode and an extraction electrode for leading the excitation electrode to the outside are formed on at least one surface; a package having a connection electrode that is hermetically housed and electrically conductively joined to the extraction electrode; A piezoelectric vibration device comprising an opening portion of the package and a lid to be airtightly joined,
The extraction electrode and the connection electrode of the piezoelectric diaphragm have an average particle diameter of 1 to 100 nm, the surface is coated with an organic coating, and the metal fine particles from which the organic coating is removed by heating are contained in an organic solvent. A piezoelectric vibration device characterized by being bonded with a dispersed metal fine particle paste bonding material. A piezoelectric diaphragm in which an excitation electrode and an extraction electrode for leading the excitation electrode to the outside are formed on at least one surface, and a base in which a plurality of independent lead terminals that are conductively joined to the extraction electrode of the piezoelectric diaphragm are formed to penetrate And a piezoelectric vibration device comprising a cap hermetically bonded to the base and hermetically sealing the piezoelectric diaphragm,
The lead electrode and the lead terminal of the piezoelectric diaphragm have an average particle diameter of 1 to 100 nm, the surface is coated with an organic coating, and the metal fine particles from which the organic coating is removed by heating are placed in an organic solvent. A piezoelectric vibration device characterized by being bonded with a dispersed metal fine particle paste bonding material. A piezoelectric diaphragm in which an excitation electrode and an extraction electrode for leading the excitation electrode to the outside are formed on at least one surface, an electronic component element constituting the piezoelectric diaphragm and a circuit, and the piezoelectric diaphragm and the electronic component element. A piezoelectric vibration device that is hermetically housed and includes a package having a connection electrode that is conductively bonded to each of the extraction electrode and the electrode of the electronic component element, and a lid that is airtightly bonded to an opening portion of the package,
Each of the conductive joints has an average particle diameter of 1 to 100 nm, and is coated with an organic coating on the surface. Metal particulate paste bonding in which metal fine particles from which the organic coating is removed by heating are dispersed in an organic solvent A piezoelectric vibration device characterized by being made of a material. A plurality of excitation electrodes and extraction electrodes corresponding to the excitation electrodes are formed on the piezoelectric diaphragm, and at least one connection between the extraction electrodes and the connection electrode is bonded by the metal fine particle paste bonding material. The piezoelectric vibration device according to claim 1. The piezoelectric vibration plate is formed with a plurality of excitation electrodes and extraction electrodes corresponding to the excitation electrodes, and the connection between the extraction electrodes and the connection electrodes is bonded by the metal fine particle paste bonding material. The piezoelectric vibration device according to claim 4. A plurality of excitation electrodes and extraction electrodes corresponding to the excitation electrodes are formed on the piezoelectric diaphragm, and at least one of the extraction electrodes is connected to the connection electrode by the metal fine particle paste bonding material, and the other extraction electrode 6. The piezoelectric vibration device according to claim 1, wherein the connection between the electrode and the connection electrode is performed by metal bonding by metal bumps. 7. The piezoelectric vibration device according to claim 1, wherein the metal fine particles of the metal fine particle paste bonding material and the metal film on the bonding surface of the extraction electrode and the connection electrode are the same kind of metal. . The piezoelectric vibration according to any one of claims 1 to 7, wherein the metal fine particle paste bonding material includes a plurality of layers, and a part of the layer is a metal fine particle paste using copper as metal fine particles. device. 9. The binder according to claim 1, wherein the metal fine particle paste bonding material includes a binder resin that mechanically bonds the extraction electrode of the piezoelectric diaphragm and the connection electrode. 10. Piezoelectric vibration device. The piezoelectric vibration device according to any one of claims 1 to 9, wherein a reducing agent for the metal fine particles is added to the metal fine particle paste bonding material. The piezoelectric vibration device according to claim 10, wherein the reducing agent is 1 to 10% by weight of palladium with respect to the metal fine particle paste bonding material. The piezoelectric vibration device according to claim 10 or 11, wherein an average particle diameter of the palladium is 1 to 60 nm.

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