JP5098621B2 - Piezoelectric device and sealing method thereof - Google Patents

Description

  The present invention relates to a piezoelectric device such as a vibrator, a resonator, an oscillator, a filter, a sensor, and a SAW device in which a piezoelectric vibrating piece is hermetically sealed in a package, and a method for hermetically sealing a package of such a piezoelectric device.

  Conventionally, surface mount types suitable for mounting on a circuit board or the like are often used as piezoelectric devices. Generally, a surface-mount type piezoelectric device has a structure in which a piezoelectric vibrating piece is sealed in a package made of an insulating material such as ceramic. In many conventional package structures, a piezoelectric vibrating piece is mounted on a box-type base on which thin plates of ceramic material are stacked, and a lid is hermetically bonded and sealed with low melting point glass or the like. In order to exhaust the gas generated from the low-melting glass during the bonding of the lid and the base so that it does not remain inside the package, or to maintain a desired atmosphere inside the package after sealing, a sealing hole is formed in the base or lid. There is known a package structure that is provided and closed after the lid is joined (for example, see Patent Documents 1 and 2).

  A typical example of this conventional surface-mount type piezoelectric vibrator is shown in FIGS. The piezoelectric vibrator 1 includes a package 3 in which a tuning fork type piezoelectric vibrating piece 2 is mounted, a base 4 in which thin plates 4a to 4c of ceramic material are stacked in a box shape, and a glass thin plate that is airtightly bonded thereon. The lid 5 is configured. In the center of the bottom portion of the base 4, a sealing hole 6 that communicates the inside and the outside of the package 3 is provided, and is closed by a low melting point metal sealing material 7 such as Au—Sn. As shown in FIG. 7C, the sealing hole 6 is provided with a step 8 on the outer surface side of the base by an outer large-diameter hole 6a and an inner small-diameter hole 6b, and the surface easily welds the sealing material 7. It is metallized with a suitable metal material. When the inside of the package 3 in which the resonator element 2 is mounted on the base 4 and the lid 5 is bonded is vacuum-sealed, the sealing hole 6 places the metal ball 9 made of the low-melting-point metal on the step 8, It is closed by heating and melting instantaneously with a laser beam or a halogen lamp.

  In addition, a quartz resonator having a structure that is further reduced in size and thickness is proposed by forming a quartz plate in which a quartz vibrating piece and an outer frame are integrated, and bonding a substrate as a base and a lid above and below, respectively. (See, for example, Patent Documents 3 and 4). Patent Document 3 describes a package structure in which a metal layer is provided on the upper and lower surfaces of an outer frame that is integrated with a crystal resonator, and the metal layer is bonded to a lid and case made of glass by anodic bonding. The package structure of Patent Document 4 is formed by removing the dirt and the like by removing ultraviolet light in an oxygen-containing atmosphere or exposure to oxygen plasma in the oxygen-containing atmosphere and cleaning the mutual bonding surface of the mirror-polished piezoelectric plate and substrate, and by forming moisture. Are bonded by hydrogen bonds of —OH groups.

  Similarly, in the piezoelectric device having such a package structure, the piezoelectric vibrating piece is bonded to the outer frame together with the upper substrate in order to discharge gas and moisture generated from the sealing material or to seal in a vacuum or a desired atmosphere. A configuration is adopted in which a sealing hole is provided in a lower substrate that seals and is closed with a sealing material such as Au—Sn. (For example, see Patent Documents 5 and 6). In Patent Document 5, a sealing hole having a step is formed by the outer large-diameter hole and the inner small-diameter hole as described above, and in Patent Document 6, the sealing hole is tapered from the outside to the inside of the package. Is formed.

  On the other hand, in order to hermetically seal a package with an electronic device such as a piezoelectric vibrator, a method using a paste-like bonding material containing metal nanoparticles has been proposed (see, for example, Patent Documents 7 and 8). The electronic component container described in Patent Document 7 is a box-shaped container or metal made of a paste-like sealing member made of metal fine particles having an average particle diameter of 1 to 100 nm and a dispersant such as amine by screen printing or an inkjet method. It joins by apply | coating to the lid | cover of this, and heating together in the atmosphere of 250 degrees C or less together. The piezoelectric device described in Patent Document 8 uses a metal fine particle paste bonding material in which metal fine particles with an average particle diameter of 1 to 100 nm coated with an organic coating on the surface are dispersed in an organic solvent, and is heated at about 200 ° C. The fine particles are fused to each other, that is, sintered, and the quartz crystal plate, the upper plate, and the lower plate are joined by intermetallic bonding between the metal fine particles and between the metal films.

JP 2003-318691 A Japanese Patent Laid-Open No. 9-193967 JP 2000-68780 A JP 7-154177 A JP2004-222053 International Publication Number WO2006 / 104265 Pamphlet JP 2005-317793 A JP 2006-186748 A

  However, in the conventional package structure in which the sealing hole is hermetically closed with the metal sealing material heated and melted with laser light or the like as described above, a part of the sealing material heated to a high temperature suddenly reaches the inside of the package. There is a risk of scattering and adhering to the surface of the piezoelectric vibrating piece to fluctuate or deteriorate its vibration characteristics, and in particular in the case of a tuning fork type vibrating piece, the electrodes and wiring may be short-circuited. Further, the gas generated from the molten sealing material is not sufficiently exhausted to the outside, and there is a possibility that the inside of the package cannot be maintained in a desired vacuum state or atmosphere. These are a major cause of reducing the performance and life of the piezoelectric device.

  In particular, when the piezoelectric device is further miniaturized, the sealing hole and the metal ball to be used become smaller. Therefore, if the output of the laser beam to be irradiated is excessive, the melted sealing material is likely to be scattered. In addition, the package may crack at the high temperature of the laser beam, which may impair the airtightness. On the other hand, if the output of the laser beam is too small, the metal ball does not melt instantaneously, causing a problem that the sealing hole is not completely airtightly closed. As a result, since a precise sealing operation is required, problems such as a decrease in yield and productivity and an increase in manufacturing cost arise.

  Therefore, the present invention has been made in view of the above-described conventional problems, and the object thereof is to cope with the downsizing of the package, and to disperse the sealing material into the conventional package and to enter the gas. Another object of the present invention is to provide a piezoelectric device capable of hermetically sealing the inside of the package without impairing the residual and without impairing the hermeticity of the package due to the high temperature of the laser beam, and a sealing method thereof.

  According to the present invention, in order to achieve the above object, a piezoelectric vibrating piece and a package for hermetically sealing the piezoelectric vibrating piece are provided, the package including a cavity for accommodating the piezoelectric vibrating piece, and a package And a sealing hole that communicates the cavity with the outside of the package, and the sealing hole forms a porous metal sintered body formed therein and a metal portion that fills the porous hole in the porous structure. There is provided a piezoelectric device hermetically closed by a sealing body composed of

  Due to the presence of the porous sintered metal body in the sealing hole, when forming the metal part, a part of the metal material that closes the sealing hole as in the prior art is rapidly melted in the cavity. There is no possibility of scattering or intrusion of outer gas, so that the vibration characteristics of the piezoelectric vibrating piece are not changed or deteriorated, and the electrodes or wirings of the piezoelectric vibrating piece are not short-circuited or deteriorated. Accordingly, it is possible to maintain and ensure the performance of the piezoelectric device, improve its reliability and durability, and further facilitate the sealing process and operation to improve productivity and yield.

In a certain embodiment, the sintered metal body includes 88 to 93 wt%, 5 to 15 wt%, 0.01 to 4 wt% of metal particles having an average particle diameter of 0.1 to 1.0 μm, an organic solvent, and a resin material. It has a porous structure having a Young's modulus of 9 to 16 GPa and a density of 10 to 17 g / cm ³ formed by sintering a metal paste blended at a ratio of 0.0% by weight. A metal sintered body obtained by sintering a metal paste composed of submicron-sized metal particles forms a porous structure having nano-sized micropores. Therefore, sealing holes are formed by metal parts that can be formed by various known methods. It can be hermetically sealed.

  In another embodiment, the submicron sized metal particles forming the metal paste can be sintered at a relatively low temperature when selected from one or more metals of Au, Ag, Pt, or Pd. preferable.

  In one embodiment, the metal part is formed by sputtering or vapor-depositing a metal material on the sintered metal body from the outside of the package. Unlike conventional technology that uses high-power laser light, the package is not damaged when the metal part is formed, and there is no risk of reducing or degrading the hermeticity of the package, ensuring the reliability and durability of the piezoelectric device. be able to.

  In another embodiment, the metal part is sputtered or vapor-deposited on the first metal part from the outside of the package, the first metal part comprising a sintered body of metal nanoparticles formed on the part of the metal sintered body on the package outer surface side. And a second metal part made of a metal material. Since only the second metal portion needs to be formed by sputtering or vapor deposition, the time required for the sealing process can be shortened and the cost can be reduced. In addition, the sintered body of metal nanoparticles can be formed at a relatively low temperature, and since the metal sintered body exists in advance below the metal nanoparticles, some of them are scattered during sintering of the metal nanoparticles or the outer gas is contained in the cavity. Therefore, the characteristics of the piezoelectric device are not fluctuated or deteriorated, and the electrode or wiring of the piezoelectric vibrating piece is not short-circuited or deteriorated.

  According to another embodiment, the metal portion is formed from a metal portion obtained by heating and melting a portion of the sintered metal body on the package outer surface side by irradiation with, for example, laser light. Since the laser beam only needs to melt a part of the metal sintered body, the output is relatively low and there is no possibility of damaging the package, so that the hermeticity of the package can be ensured.

  According to yet another embodiment, the metal portion is formed from a metal portion obtained by melting and solidifying a metal material different from the metal sintered body by irradiation with, for example, laser light. Since the sintered metal exists in the sealing hole, the output of the laser beam for melting the metal material is relatively low, and there is no possibility of damaging the package, so that the airtightness of the package can be ensured. .

  According to another aspect of the present invention, in order to hermetically seal a package of a piezoelectric device having a cavity for accommodating a piezoelectric vibrating piece and a sealing hole communicating with the cavity to the outside, sealing of the package A process of forming a porous metal sintered body in the hole, a process of mounting a piezoelectric vibrating piece on the package, and forming a metal part that fills the fine pores of the porous structure in the metal sintered body of the sealing hole Accordingly, there is provided a method for sealing a piezoelectric device including a process of forming a sealing body that hermetically closes the sealing hole.

  For forming the metal sintered body and the metal part, since existing equipment generally used for manufacturing a piezoelectric device can be used, an increase in manufacturing cost can be suppressed, batch processing can be performed, and production efficiency can be improved. Manufacturing costs can be reduced.

In some embodiments, the process of forming the sintered metal body comprises 88-93 wt%, 5-15 wt%, 0 wt% metal particles having an average particle size of 0.1-1.0 μm, an organic solvent, and a resin material. By heating and sintering the metal paste blended at a ratio of 0.01 to 4.0% by weight, the metal sintered body is made to have a porous structure with a Young's modulus of 9 to 16 GPa and a density of 10 to 17 g / cm ^3. It consists of a process of forming. Metal paste made of submicron-sized metal particles can be easily filled using a known method such as screen printing, dispenser, ink jet, photoresist method, etc., even if the sealing hole has a smaller diameter. Therefore, even if the piezoelectric device is further reduced in size, it can be sufficiently handled.

  In another embodiment, the metal particles of the metal paste are selected from one or more metals of Au, Ag, Pt, or Pd and can be sintered at a relatively low temperature, which may cause deformation or alteration of the package. Is preferred.

  In one embodiment, the process of forming the metal part includes the process of sputtering or vapor-depositing a metal material on the sintered metal body from the outside of the package, which may damage the package unlike conventional techniques using high-power laser light. Therefore, since the airtightness of the package is not lowered or deteriorated, the reliability and durability of the piezoelectric device can be ensured.

  In another embodiment, the process of forming the metal part forms a first metal part made of a sintered body of metal nanoparticles in a part of the metal sintered body on the package outer surface side, and the first metal part is formed from the outside of the package. And forming a second metal part by sputtering or vapor-depositing a metal material. Since the amount of metal formed by sputtering or vapor deposition is only the second metal portion, the time required for the sealing process can be shortened to improve productivity and reduce costs. In addition, since the sintered body of metal nanoparticles can be formed at a relatively low temperature, and the sintered metal body is present in the sealing hole in advance during sintering, a part of the metal nanoparticles may be scattered in the cavity or the outer gas. There is no risk of intrusion. Therefore, the characteristics of the piezoelectric device do not fluctuate or deteriorate, and the electrode or wiring of the piezoelectric vibrating piece does not short or deteriorate.

  In another embodiment, the process of forming the metal part is a process of heating and melting and solidifying a portion of the sintered metal body on the package outer surface side by irradiation with, for example, laser light. Since only a part of the sintered metal is melted, the output of the laser light can be relatively low and there is no possibility of damaging the package, so that the hermeticity of the package can be ensured.

  In still another embodiment, the process of forming the metal part is a process of supplying a metal material such as a metal ball to the outside of the sintered metal body and solidifying the metal material by heating and melting it by irradiation with a laser beam or the like, for example. Consists of. When the metal material is heated and melted, a metal sintered body is present in the sealing hole, so that the output of the laser beam can be relatively low, and there is no possibility of damaging the package. it can.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIGS. 1A and 1B schematically show a first embodiment of a surface-mounted crystal resonator to which the present invention is applied. The crystal resonator 11 of the first embodiment includes a package 13 that hermetically seals a tuning fork type crystal resonator element 12 inside. The package 13 includes a box-shaped base 14 in which three generally rectangular ceramic thin plates 14a to 14c are laminated, and a lid 15 made of a rectangular thin plate made of glass or ceramics hermetically bonded to the upper end surface thereof with a low melting point glass or the like. And have. A connection electrode 17 is formed on the bottom surface of the cavity 16 defined by the base and the lid, and the crystal vibrating piece 12 is supported substantially horizontally in a cantilever manner by fixing its base end portion 12a with a conductive adhesive. Yes.

  A sealing hole 18 that communicates the inside and the outside of the package 13 is formed in the base 14 at the substantially center of the bottom surface of the cavity 16. As shown in FIG. 1C, the sealing hole 18 includes an outer large-diameter hole 18a that opens to the bottom surface of the base 14 and an inner small-diameter hole 18b that opens to the bottom surface of the cavity. A thin film 19 made of a suitable metal material is formed by metallization. The sealing hole 18 is airtightly closed by the sealing body 20 according to the present invention.

The sealing body 20 includes a porous metal sintered body 21 formed so as to close both the large diameter hole 18a and the small diameter hole 18b in the sealing hole. As will be described later, the sintered metal 21 has a Young's modulus of 9 to 16 GPa and a density of 10 to 10 obtained by sintering a metal paste made of metal submicron particles made of one or more of Au, Ag, Pt, or Pd, for example. It has a porous structure of 17 g / cm ³ . A metal portion 22 is formed at a predetermined depth in the base bottom side portion of the sintered metal body 21 so as to fill the micropores of the porous structure over the entire cross section of the sealing hole 18. The sealing hole is airtightly closed.

  A process of forming the sealing body 20 in the sealing hole 18 and sealing the crystal resonator package 13 in an airtight manner will be described. As shown in FIG. 2A, by laminating and bonding the ceramic thin plate 14a having the large diameter hole 18a, the ceramic thin plate 14b having the small diameter hole 18b, and the ceramic thin plate 14c forming the outer frame of the cavity 16, A box-shaped base 14 is formed. In the portion of the ceramic thin plate 14b where the step is formed, a thin film 19 of an appropriate metal material is formed on the surface in advance by metallization.

  Next, the metal paste 23 of the present invention is filled into the sealing hole 18 with the bottom side of the base 14 facing upward. The metal paste 23 is composed of metal particles 24, an organic solvent 25, and a resin material 26. The metal particles 24 are, for example, submicron metal powders having an average particle diameter of 0.1 to 1.0 μm made of one or more of Au, Ag, Pt, and Pd. The organic solvent 25 uses ester alcohol or the like that can be evaporated at a relatively low temperature of about 200 ° C., and the metal particles are dispersed substantially uniformly therein. For example, a cellulose resin material is used as the resin material 26, and is added to give a certain degree of viscosity to the metal paste. Due to this viscosity, the metal paste 23 exhibits a sufficient shape and is held therein without easily flowing out after filling the sealing hole 18.

  According to this invention, the metal paste 23 is mix | blended in the ratio of 88-93 weight% of metal powder, 5-15 weight% of organic solvents, and 0.01-4.0 weight% of resin materials. By including a small amount of the resin material in this way, the metal paste can be filled using a known method such as screen printing, dispenser, ink jet, or photoresist method. Furthermore, since the metal paste has a larger particle size and a significantly smaller proportion of organic solvent than a metal paste using conventional nano-micron particles, it is sintered at a relatively low temperature of, for example, about 200 to 300 ° C. As a result, a sintered body having a porous structure in which the metal particles are fused and densified is easily formed. In addition, the organic solvent and the resin material in the metal paste sealing material can be sufficiently evaporated so as not to substantially remain in the sintered body even by a sintering process at a low temperature.

  As shown in FIG. 2B, the base 14 filled with the metal paste 23 in the sealing hole 18 is heated at a relatively low temperature of about 200 to 300 ° C. for a short time, for example, about 10 to 30 minutes. Do. This sintering process is performed using known means such as a hot plate, a clean oven, a belt furnace, or the like. Since heating is performed at a relatively low temperature, there is no possibility of deformation such as warpage in the base 14.

By the sintering process, the organic solvent 25 and the resin material 26 are evaporated from the metal paste 23, and the adjacent metal particles 24 are fused together to form a porous metal sintered body 21 in close contact with each other. The metal sintered body 21 is preferably formed in a porous structure having a Young's modulus of 9 to 16 GPa and a density of 10 to 17 g / cm ³ . In the porous structure, the metal particles are fused while maintaining their original spherical shape, exhibiting necessary and sufficient strength as the sealing body 20, and between the fused submicron-sized metal particles 24. It has nano-sized micropores formed in. In addition, by using submicron-sized metal particles, the metal sintered body 21 can be formed by filling the metal paste 23 even when the sealing hole 18 has a smaller diameter. Therefore, even if the package 13 is further reduced in size, it can be sufficiently handled.

  The metal sintered body 21 is firmly fixed in the sealing hole 18 by the metal particles 24 being densified at the interface with the stepped metal thin film 19 in the sealing hole 18 and bonded to the metal thin film. To do. In another embodiment, the metal sintered body 21 can be more firmly fixed by forming the metal thin film 19 on the entire inner surface of the sealing hole 18.

  Further, the resin material 26 may not be completely evaporated even by the sintering process, and a part of the resin material 26 may remain in the metal sintered body 21. In that case, the remaining resin material enters the gaps between the metal particles 21, so that there is no influence on the construction of the porous structure.

  In another embodiment, the sintering process is performed in two stages. First, the base 14 in which the sealing hole 18 is filled with the metal paste 23 is heated at a low temperature of about 90 ° C. for about 30 minutes under a reduced pressure using, for example, a clean oven, thereby performing a preliminary sintering process. The organic solvent is removed by evaporation. Next, the base 14 is subjected to a main sintering process by heating at a relatively low temperature of about 270 ° C. for about 2 hours under a high vacuum using, for example, an annealing bath, and the above-described desired porous structure metal firing is performed. A ligature 21 is formed. By such a two-step sintering process, the metal particles 24 are more uniformly dispersed, and a porous structure having more uniform nano-sized micropores is obtained.

  Next, the crystal vibrating piece 12 is mounted on the base 14, and the lid 15 is hermetically bonded to the upper end surface thereof to seal the package 13. The lid 15 and the base 14 can be joined by various other known methods such as seam welding, metal joining, brazing material, etc. in addition to the above-described low melting point glass. The package 13 is placed in a vacuum atmosphere with the base 14 bottom face up as shown in FIG. 2C, and the surface of the metal sintered body 21 exposed in the sealing hole 18 is made of an appropriate metal material from above. Sputter.

  The sputtered metal material enters from the bottom surface side of the base into the fine holes of the porous structure of the metal sintered body 21 and is deposited so as to fill the fine holes, and further densely forms the film on the metal sintered body 21. As a result, as shown in FIG. 1C, a metal portion 22 having a predetermined depth is formed over the entire cross section of the sealing hole 18. The metal part 22 can be similarly formed by vapor deposition of a metal material. Any metal that can be sputtered or vapor-deposited can be used as the metal material for forming the metal part, but generally used metals such as Au, Ag, Cr, Ni, Pd, and Ti are preferable. . Further, since the sputtered metal material is captured by the porous structure of the sintered metal 21, there is no possibility of reaching the cavity 16 of the package 13. Therefore, unlike the prior art, there is no possibility of causing a short circuit in the electrodes and wiring of the crystal resonator element, and the performance of the crystal resonator can be maintained and guaranteed.

  Thus, the sealing hole 18 can be hermetically closed by forming the sealing body 20 including the metal sintered body 21 and the metal portion 22 that fills the microscopic hole of the porous structure from the outside of the package. The metal part 22 does not need to completely fill all the fine holes of the porous structure, and may be formed to a predetermined depth that can close the sealing hole 18 in an airtight manner. Formation of the sealing body 20 can utilize existing equipment generally used for manufacturing a piezoelectric device, and can suppress an increase in manufacturing cost. Further, the hermetic sealing of the package according to the present embodiment can be batch-processed, so that the production efficiency can be improved and the manufacturing cost can be reduced.

  3A to 3C show a process of hermetically sealing the sealing hole 18 according to a modification of the first embodiment. The process from forming the metal sintered body 21 in the sealing hole 18 of the base 14, mounting the crystal vibrating piece 12 to the base, and joining the lid 15 is the same as in the first embodiment. Omitted. In this embodiment, the package 13 encapsulating the crystal vibrating piece 12 is placed in a vacuum atmosphere with the bottom of the base 14 facing upward as shown in FIG. 3A, and the nano metal paste 27 made of metal nanoparticles is sealed. The stop hole 18 is filled on the metal sintered body 21.

  The nano metal paste 27 is obtained by dispersing metal nanoparticles having an average particle diameter of 1 to 100 nm in an organic solvent or a dispersing material as described above in relation to the prior art, and a commercially available product can be used. The metal used for the metal nanoparticles is not particularly limited. For example, Au, Ag, Cu, Pt, Pd, Rd, Os, Ru, Ir, Fe, Sn, Zn, Co, Ni, Ti, Ta, W, In In general, any one kind of Si or an alloy of two or more kinds is used. As the organic solvent, alcohol such as ethanol, amine, thiol and the like are used.

  The package 13 is appropriately heated to sinter the nano metal paste 27. By this sintering treatment, the organic solvent is removed by evaporation from the nanometal paste 27, the metal nanoparticles are fused in the fine pores of the porous structure of the metal sintered body 21, and the metal nanoparticles are bonded to each other. To fuse. As a result, the first metal portion 28 is formed at a certain depth in the portion on the bottom side of the base of the sintered metal body 21 so as to fill the fine holes of the porous structure over the entire cross section of the sealing hole 18. Is done.

  The conditions for the sintering treatment of the nanometal paste 27 vary depending on the metal type and particle size of the metal nanoparticles to be used, the type of organic solvent to be used, their combination, and the like. For example, when the metal nanoparticles are Au, it is known to sinter at about 250 ° C. Generally, it can be sintered at a temperature of about 200-300 ° C. or lower, similar to the metal paste comprising submicron particles of the present invention. The organic solvent vaporized by the sintering of the nano metal paste 27 is sintered in the porous structure of the metal sintered body 21 and in a vacuum-sucked atmosphere, so that the penetration into the cavity 16 is suppressed. Therefore, there is no possibility that the vibration characteristics of the quartz crystal resonator element fluctuate or deteriorate as in the prior art, and the performance of the quartz crystal resonator can be maintained and guaranteed.

  Next, the package 13 is exposed in the sealing hole 18 in the same manner as in the first embodiment, with the bottom surface of the base 14 facing upward as shown in FIG. The surface of one metal part 28 is sputtered from above with an appropriate metal material. By this sputtering, a second metal part 29 made of a dense metal film is formed on the first metal part 28. The second metal part 29 can be similarly formed by vapor deposition of a metal material.

  According to the present embodiment, the first metal portion 28 and the second metal portion 29 are used to fill the porous holes in the porous structure of the metal sintered body 21 from the outside of the package over the entire cross section of the sealing hole 18. A metal part 30 having a depth is formed. Thus, by forming the sealing body 31 including the metal sintered body 21 and the metal portion 30, the sealing hole 18 can be hermetically closed. The first metal portion 28 does not have to completely fill all the fine holes of the porous structure, and has a predetermined depth that allows the sealing hole 18 to be airtightly closed in cooperation with the second metal portion 29. What is necessary is just to form.

  Further, in this embodiment, the amount of sputtered metal is smaller than that in the first embodiment, so that the time required to close the sealing hole 18 can be shortened. Similarly to the first embodiment, the sealing body 31 of the present embodiment can be formed by using existing equipment generally used for manufacturing a piezoelectric device, and an increase in manufacturing cost can be suppressed. The hermetic sealing of the package according to the present embodiment can also be batch-processed, and similarly it is possible to improve production efficiency and reduce manufacturing costs.

  4A and 4B show a process of hermetically sealing the sealing hole 18 according to another modification of the first embodiment. The process from forming the metal sintered body 21 in the sealing hole 18 of the base 14, mounting the crystal vibrating piece 12 to the base, and joining the lid 15 is the same as in each of the above embodiments. Omitted. In this embodiment, as shown in FIG. 4A, the package 13 in which the crystal vibrating piece 12 is sealed is placed in a vacuum atmosphere with the bottom surface of the base 14 facing up, and the sintered metal in the sealing hole 18 is placed. 21 is irradiated with laser light. In another embodiment, in addition to the laser light, other heating means such as a halogen lamp can be used.

  As described above, the metal sintered body 21 is formed in a state in which the submicron metal particles 24 are fused while maintaining a relatively original shape. By irradiation with laser light, the metal particles 24 of the metal sintered body 21 are melted at the upper surface of the metal sintered body, that is, the portion on the base bottom surface side. The molten metal is solidified while filling the fine pores of the porous structure, so that the metal portion 32 is formed on the entire surface of the cross section of the sealing hole 18 as shown in FIG. It is formed with a predetermined depth. Thus, by forming the sealing body 33 including the metal sintered body 21 and the metal portion 32, the sealing hole 18 is airtightly closed.

  In this embodiment, it is not necessary to melt the entire metal sintered body 21 by laser light irradiation, and the metal portion 32 may be formed to a depth that can ensure hermetic sealing of the sealing hole 18. By maintaining the porous structure at the lower side of the metal sintered body 21, that is, the cavity side portion, the metal particles melted by the laser light irradiation do not reach the cavity 16 of the package 13. Further, even when outer gas is generated due to melting of the metal particles, the processing is performed by the porous structure and in a vacuum-sucked atmosphere, so that intrusion into the cavity 16 is suppressed. Accordingly, there is no possibility that the vibration characteristics of the quartz crystal resonator element fluctuate or deteriorate as in the prior art, and there is no possibility that a short circuit occurs in the electrode or wiring of the quartz resonator element, and the performance of the crystal resonator can be maintained and guaranteed.

  Further, since the laser beam output only melts the metal sintered body 21 partially, it can be considerably smaller than the case of melting the metal ball in the prior art. As a result, there is no possibility of damaging the package 13 with laser light, and it is possible to prevent deterioration or deterioration of airtightness due to occurrence of cracks or the like.

  5A and 5B show a process of hermetically sealing the sealing hole 18 according to still another modification of the first embodiment. The process from forming the metal sintered body 21 in the sealing hole 18 of the base 14, mounting the crystal vibrating piece 12 to the base, and joining the lid 15 is the same as in each of the above embodiments. Omitted. In the present embodiment, the package 13 in which the crystal vibrating piece 12 is sealed is placed in a vacuum atmosphere with the bottom of the base 14 facing upward as shown in FIG. 5A, and the sintered metal 21 in the sealing hole 18 is placed. A metal ball 34 is placed on the surface. The metal ball 34 is an alloy made of one kind of metal such as Ag and Cu, or two or more kinds of metals such as AuGe, AuSn, AuSi, AgCu, and SnPb, as in the case of the metal ball 7 shown in FIG. It is formed.

  Next, as shown in FIG. 5B, laser light is irradiated toward the metal ball 34. By irradiating the laser beam, the metal ball 34 is melted and solidified while filling the fine pores of the porous structure, so that the metal portion 35 extends over the entire cross section of the sealing hole 18 on the metal sintered body 21. To a predetermined depth. Thus, by forming the sealing body 36 including the metal sintered body 21 and the metal portion 35, the sealing hole 18 is hermetically closed. In another embodiment, in addition to the laser light, other heating means such as a halogen lamp can be used.

  Also in this embodiment, the presence of the porous metal sintered body 21 in the sealing hole 18 scatters the metal material from the metal ball 34 melted by the irradiation of the laser beam to the cavity 16 of the package 13. There is no risk of reaching. Further, even when outer gas is generated due to melting of the metal ball, the processing is performed in the porous structure and in a vacuum-sucked atmosphere, so that the penetration into the cavity 16 is suppressed. Accordingly, there is no possibility that the vibration characteristics of the quartz crystal resonator element fluctuate or deteriorate as in the prior art, and there is no possibility that a short circuit occurs in the electrode or wiring of the quartz resonator element, and the performance of the crystal resonator can be maintained and guaranteed.

  In addition, since the metal sintered body 21 having the porous structure is present below the metal ball 34, the metal ball 34 may flow into the cavity 16 from the sealing hole 18 without melting instantaneously as in the prior art. There is no. Therefore, the output of the laser beam can be considerably smaller than the conventional one. As a result, there is no possibility of damaging the package 13 with laser light, and it is possible to prevent deterioration or deterioration of airtightness due to occurrence of cracks or the like.

  FIGS. 6A and 6B schematically show a second embodiment of a surface-mount type crystal resonator to which the present invention is applied. The crystal resonator 41 of the second embodiment includes an intermediate crystal plate 44 having a tuning fork type crystal vibrating piece 42 and an outer frame 43 integrally coupled at its base end 42a, an upper substrate 45 serving as a package lid, and A lower substrate 46 serving as a base is provided. The upper and lower substrates 45 and 46 have recesses 45 a and 46 a formed on the surface facing the intermediate crystal plate 44, respectively. The upper and lower substrates 45 and 46 are laminated and integrally bonded to the upper and lower surfaces of the outer frame 43 of the intermediate crystal plate 44, so that the tuning fork type crystal vibrating piece 42 is placed in the cavity defined by the recesses 45a and 46a. A sealed package is formed inside.

  Similarly, the upper and lower substrates 45 and 46 are preferably formed of a crystal thin plate, or can be formed of a glass material, silicon, ceramics, or the like. The joint portions 47 to 49 between the outer frame 43 and the upper and lower substrates 45 and 46 are formed by metal bonding between metal thin films. For example, anodic bonding, crystal surfaces or direct bonding between a crystal surface and a metal thin film, Other known means such as low melting point glass and brazing material can be used.

  The lower substrate 46 is formed with a sealing hole 50 at the substantially center thereof for communicating the inside and the outside of the package. As shown in FIG. 6C, the sealing hole 50 is formed in a truncated cone shape having a tapered shape from the outer opening on the bottom surface of the lower substrate 46 toward the inner opening on the bottom surface of the cavity. 51 is airtightly closed. A thin film 52 of an appropriate metal material is formed on the inner peripheral surface of the sealing hole 50 by metallization.

Similar to the sealing body 20 of the first embodiment, the sealing body 50 sinters a metal paste made of submicron particles of one kind or two or more kinds of metals of Au, Ag, Pt or Pd and seals the sealing. It is composed of a sintered metal 53 having a porous structure with a Young's modulus of 9 to 16 GPa and a density of 10 to 17 g / cm ³ formed so as to close the hole. When the sintered metal 53 is formed, the sealing hole 50 is tapered, so that the metal paste filled therein is maintained in the sealing hole without flowing to the cavity side.

  A metal portion 54 is formed at a predetermined depth in the lower substrate bottom surface portion of the metal sintered body 53 so as to fill the fine holes of the porous structure over the entire cross section of the sealing hole 50. Thus, the sealing hole is airtightly closed. Since the sealing body 50 is formed according to the same process as each said Example, detailed description is abbreviate | omitted.

  Similarly, in the second embodiment, by using a metal paste made of submicron-sized metal particles, the sintered metal body 51 can be formed even if the diameter of the sealing hole 50 is further reduced. This can sufficiently cope with further downsizing of the child 41. Further, due to the presence of the sintered metal 51, when the metal portion 54 is formed, there is no possibility that part of the metal material heated and melted as in the prior art is scattered in the cavity or the outer gas enters, and the laser Since the package is not damaged by the high heat of the light, there is no risk of fluctuation or deterioration of the vibration characteristics, short-circuiting of the electrodes or wiring of the crystal resonator element, and deterioration of airtightness, and maintaining and ensuring the performance of the crystal unit. Can do.

  The present invention is not limited to the above embodiments, and can be implemented with various modifications or changes within the technical scope thereof. For example, the sealing hole of the package can be formed in various shapes, and can be provided not on the base side but on the lid side. In addition to the vibrator, various piezoelectric devices such as a resonator, an oscillator, a filter, a sensor, and a SAW device, and other electronic devices can be similarly applied.

(A) is a longitudinal sectional view of a first embodiment of a tuning fork type crystal resonator according to the present invention, (B) is a bottom view thereof, and (C) is a partially enlarged sectional view showing a sealing hole. (A) A figure is a longitudinal cross-sectional view of the base of 1st Example, (B), (C) figure is a partial expanded sectional view which shows the process of forming a sealing body in a sealing hole. (A)-(C) figure is a partial expanded sectional view which shows the process of forming the sealing body by the modification of 1st Example. (A), (B) figure is a partial expanded sectional view which shows the process of forming the sealing body by another modification of 1st Example. (A), (B) figure is a partial expanded sectional view which shows the process of forming the sealing body by another modification of 1st Example. (A) is a longitudinal sectional view of a second embodiment of a tuning fork type crystal resonator according to the present invention, (B) is a bottom view thereof, and (C) is a partially enlarged sectional view showing a sealing hole. (A) is a longitudinal sectional view of a typical example of a conventional tuning fork type crystal resonator, (B) is a bottom view thereof, and (C) is a partially enlarged sectional view showing a procedure for closing a sealing hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator, 2 ... Piezoelectric vibration piece, 3, 13 ... Package, 14, 14 ... Base, 4a-4c, 14a-14c ... Thin plate, 5, 15 ... Lid, 6, 18, 50 ... Sealing hole, 6a, 18a ... large diameter hole, 6b, 18b ... small diameter hole, 7 ... sealing material, 8 ... step, 9, 34 ... metal ball, 11, 41 ... crystal resonator, 12, 42 ... crystal resonator element, 12a, 42a ... Base end portion, 16 ... Cavity, 17 ... Connection electrode, 19, 52 ... Thin film, 20, 31, 33, 36, 51 ... Sealed body, 21, 53 ... Metal sintered body, 22, 30, 32, 35, 54 ... Metal part, 23 ... Metal paste, 24 ... Metal particles, 25 ... Organic solvent, 26 ... Resin material, 27 ... Nano metal paste, 28 ... First metal part, 29 ... Second metal part, 43 ... Outside Frames 43, 44 ... intermediate crystal plate, 45 ... upper substrate, 46 ... lower substrate, 45a, 46 ... recess, 47-49 ... junction.

Claims (14)

A piezoelectric vibrating piece, and a package for hermetically sealing the piezoelectric vibrating piece,
The package has a cavity for accommodating the piezoelectric vibrating piece, and a sealing hole that opens to an outer surface of the package and communicates the cavity with the outside of the package;
The piezoelectric device is characterized in that the sealing hole is hermetically closed by a sealing body formed of a sintered metal body having a porous structure formed therein and a metal portion filling the fine holes of the porous structure. . The metal sintered body comprises 88 to 93 wt%, 5 to 15 wt%, and 0.01 to 4.0 wt% of metal particles having an average particle diameter of 0.1 to 1.0 µm, an organic solvent, and a resin material. 2. The piezoelectric device according to claim 1, having a porous structure having a Young's modulus of 9 to 16 GPa and a density of 10 to 17 g / cm ³ formed by sintering a metal paste blended at a ratio.   3. The piezoelectric device according to claim 2, wherein the metal particles of the metal paste are made of one or more metals of Au, Ag, Pt, or Pd.   4. The piezoelectric device according to claim 1, wherein the metal part is made of a metal material sputtered or vapor-deposited on the metal sintered body from the outside of the package.   The metal part is a first metal part formed of a sintered body of metal nanoparticles formed on a part of the metal sintered body on the package outer surface side, and a metal sputtered or deposited on the first metal part from the outside of the package The piezoelectric device according to claim 1, wherein the piezoelectric device is formed of a second metal portion made of a material.   4. The piezoelectric device according to claim 1, wherein the metal portion is a metal portion obtained by melting and solidifying a portion of the metal sintered body on the package outer surface side.   The piezoelectric device according to any one of claims 1 to 3, wherein the metal portion is formed of a metal portion obtained by melting and solidifying a metal material different from the metal sintered body. A method of hermetically sealing a package of a piezoelectric device having a cavity for accommodating a piezoelectric vibrating piece and a sealing hole communicating with the cavity to the outside,
Forming a porous metal sintered body in the sealing hole of the package;
Mounting the piezoelectric vibrating piece on the package;
A step of forming a sealing body that hermetically closes the sealing hole by forming a metal portion that fills the porous hole of the porous structure in the sintered metal body of the sealing hole. A method for sealing a piezoelectric device. In the process of forming the metal sintered body, the metal particles having an average particle diameter of 0.1 to 1.0 μm, the organic solvent, and the resin material are 88 to 93 wt%, 5 to 15 wt%, and 0.01 to 4. From the process of forming the metal sintered body to have a porous structure with a Young's modulus of 9 to 16 GPa and a density of 10 to 17 g / cm ³ by heating and sintering a metal paste blended at a ratio of 0% by weight. The method for sealing a piezoelectric device according to claim 8, wherein:   The method for sealing a piezoelectric device according to claim 9, wherein the metal particles of the metal paste are made of one or more metals of Au, Ag, Pt, or Pd.   11. The method for sealing a piezoelectric device according to claim 8, wherein the step of forming the metal portion includes a step of sputtering or vapor-depositing a metal material on the sintered metal body from the outside of the package. Stop method.   In the process of forming the metal part, a first metal part made of a sintered body of metal nanoparticles is formed on a part of the metal sintered body on the package outer surface side, and the metal is applied to the first metal part from the outside of the package. The method for sealing a piezoelectric device according to claim 8, comprising a step of forming a second metal part by sputtering or vapor-depositing a material.   11. The method for sealing a piezoelectric device according to claim 8, wherein the step of forming the metal portion includes a step of melting and solidifying a portion of the metal sintered body on the package outer surface side. Method.   11. The piezoelectric device according to claim 8, wherein the process of forming the metal part includes a process of supplying a metal material to the outside of the sintered metal body and melting and solidifying the metal material. Sealing method.

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