JP2011129689A - Terminal electrode and method of manufacturing terminal electrode - Google Patents

Abstract

The present invention provides a method of manufacturing a terminal electrode that can sufficiently suppress the performance degradation of a ceramic body due to the formation of the terminal electrode and can manufacture an electronic component having excellent reliability.
An application step of applying a paste containing a first metal component and a glass component on a ceramic body for an electronic component, and a firing step of firing the paste on the ceramic body to form an underlayer. And a film forming step of forming a film containing the second metal component on the underlayer by a dry film forming method to obtain a terminal electrode having the underlayer and a film covering the underlayer. Electrode manufacturing method.
[Selection figure] None

Description

  The present invention relates to a method for manufacturing terminal electrodes and electronic components.

  As a terminal electrode provided in a ferrite core or a multilayer electronic component, an electrode in which a plating film is formed on a base layer made of metal is used. Since such a terminal electrode is mounted on a substrate for various information devices using solder, it is required to have good solderability.

  For example, in Patent Document 1, a terminal electrode provided on a ferrite core is manufactured by forming a plating film such as Ni, Sn, Sn-Pb on a metal layer made of silver, a silver alloy, or copper. It has been proposed.

  Electronic parts such as ferrite cores and multilayer electronic parts are required to have further improved performance as the electronic equipment on which they are mounted has been improved in function and quality. It is required to do.

Japanese Patent Laid-Open No. 10-172832

  However, in the method of manufacturing a terminal electrode as in Patent Document 1, there is a concern that the performance of the electronic component is degraded as the plating film is formed. For example, when a terminal electrode is formed on a chip body to produce a multilayer ceramic capacitor, if the surface layer of the terminal electrode is formed by a nickel plating film and an Sn plating film by a barrel plating method or the like, the plating solution is removed from the chip body. May enter the inside of the ceramic body constituting the. When such an event occurs, there is a concern that metal deposits and electrolyte remain inside the ceramic body, resulting in a short circuit.

  Also, if the internal electrode is partially exposed on the surface on which the nickel plating film is formed due to insufficient formation of the base layer of the terminal electrode, the nickel plating film occludes hydrogen during plating formation. This hydrogen is confined in the Sn plating film, which may cause a decrease in the insulation resistance value. Furthermore, it is also conceivable that ceramic bodies or chip bodies are brought into contact with each other during the plating process, and cracks or the like caused by this contact may cause the plating solution to enter the ceramic body.

  Moreover, when making the base layer used as the base of a plating film into a metal layer which consists of a metal like patent document 1, in order to form the said metal layer, it is necessary to bake at high temperature. As a result, there is a concern that the metal element contained in the metal layer diffuses into the ceramic body and the magnetic characteristics and electrical characteristics of the ceramic body deteriorate.

  The present invention has been made in view of the above circumstances, and a method of manufacturing a terminal electrode capable of sufficiently suppressing the performance degradation of the ceramic body associated with the formation of the terminal electrode and manufacturing an electronic component having excellent reliability. And it aims at providing the manufacturing method of an electronic component.

  In order to achieve the above object, according to one aspect of the present invention, there is provided a method for manufacturing a terminal electrode provided on a ceramic body of an electronic component, wherein a paste containing a first metal component and a glass component is ceramic. A coating step for coating on the base body, a firing step for firing the paste on the ceramic body to form an underlayer, and a second metal layer different from the first metal component on the underlayer by a dry film forming method. Forming a film containing the metal component, and obtaining a terminal electrode having a base layer and a film covering the base layer.

  In the present invention, since the underlayer is formed using a paste containing the first metal component and the glass component, even if a refractory metal such as Ni is used as the first metal component, An underlayer having excellent adhesion can be formed at a sufficiently low firing temperature. Moreover, since the film is formed by the dry film forming method, it is possible to prevent the plating solution from entering the ceramic body. Due to these factors, it is possible to manufacture a terminal electrode that can sufficiently suppress the deterioration of the electrical characteristics and magnetic characteristics of the ceramic body and obtain an electronic component with excellent reliability.

  In the manufacturing method of this invention, it is preferable to have the surface treatment process of blasting the surface of a base layer after a baking process. This makes it possible to remove the glass deposited on the surface of the underlayer when glass floats in the underlayer during the firing process, and to improve the adhesion between the underlayer and the film formed thereafter. be able to.

  The dry film forming method in the film forming step of the manufacturing method of the present invention is preferably a cold spray method. According to the cold spray method, even when glass float occurs on the surface of the underlayer during the firing process, the material particles containing the second metal component collide with the surface of the underlayer, so that the surface of the underlayer A film can be formed by adhering material particles while removing the glass. For this reason, the terminal electrode excellent in the adhesiveness of a base layer and a membrane | film | coat can be manufactured efficiently.

  The first metal component in the present invention preferably contains a metal containing at least one of Ni, Ti, Ag and Cu, or an alloy containing the metal. As a result, even if the base layer is formed by firing at a relatively low temperature, a terminal electrode having excellent adhesion can be produced.

  Moreover, it is preferable that the 2nd metal component in this invention contains the metal containing at least 1 type of Sn and Au, or the alloy containing the said metal. As a result, the solder wettability and the connection strength with the solder are further improved, and an electronic component with further improved reliability can be obtained.

  Further, according to another aspect of the present invention, in another aspect, an application step of applying a paste containing a first metal component and a glass component onto a ceramic body, and firing the paste on the ceramic body to form an underlayer And a film-forming step of forming a film containing the second metal component on the base layer by a dry film-forming method to obtain a terminal electrode having a base layer and a film covering the base layer. An electronic component manufacturing method comprising a ceramic body and a terminal electrode thereon is provided.

  In the present invention, since the underlayer is formed using a paste containing the first metal component and the glass component, even if a refractory metal such as Ni is used as the first metal component, An underlayer having excellent adhesion can be formed at a sufficiently low firing temperature. Further, since the film is formed by the dry film forming method, it is possible to prevent corrosion of the ceramic body surface by the plating solution and invasion of the plating solution into the inside of the body. Due to these factors, it is possible to manufacture a highly reliable electronic component in which the electrical characteristics and magnetic characteristics of the ceramic body are sufficiently suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the terminal electrode which can suppress the performance fall of the ceramic element body accompanying formation of a terminal electrode, and can manufacture the electronic component which is excellent in reliability, and the manufacturing method of an electronic component are provided. can do.

It is a perspective view which shows an example of the ceramic core obtained by the manufacturing method of this invention. It is sectional drawing which shows typically an example of the ceramic core obtained by the manufacturing method of this invention. It is sectional drawing which shows typically an example of the coil components obtained by the manufacturing method of this invention. It is a perspective view which shows an example of the multilayer ceramic capacitor obtained by the manufacturing method of this invention. It is sectional drawing which shows typically an example of the multilayer ceramic capacitor obtained by the manufacturing method of this invention.

  In the following, preferred embodiments of the present invention will be described with reference to the drawings as the case may be. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

<First Embodiment>
FIG. 1 is a perspective view of a ceramic core obtained by the manufacturing method of the present embodiment. The ceramic core 100 has a drum shape as shown in FIG.

  2 is a schematic cross-sectional view taken along line II-II of the ceramic core of FIG. As shown in FIGS. 1 and 2, the ceramic core 100 includes a drum-shaped ceramic body 10 having a winding core portion 12 and a pair of flange portions 14 formed at both ends of the winding core portion 12 in the axial direction. And a pair of terminal electrodes 20 provided on one flange 14 of the ceramic body 10.

  As shown in FIGS. 1 and 2, both the core part 12 and the collar part 14 of the ceramic body 10 have a cylindrical shape, and the core part 12 and the collar part 14 are integrally formed. ing. The pair of terminal electrodes 20 are provided so as to cover a part of the peripheral side surface 16 and a part of the end surface 18 in the flange portion 14 of the ceramic body 10, respectively. The terminal electrode 20 has a laminated structure in which a base layer 22 and a film 24 are laminated from the ceramic body 10 side.

  The manufacturing method of this embodiment is a manufacturing method of the terminal electrode 20 which manufactures the terminal electrode 20 on the ceramic body 10 for ceramic cores. The manufacturing method includes a preparation process for producing a ceramic body 10 for the ceramic core 100, a coating process for applying a paste containing a first metal component and a glass component on the ceramic body 10, and a ceramic body. A baking step of baking the paste on the body 10 to form the underlayer 22, a surface treatment step of blasting the surface of the underlayer 22, and a second metal component on the underlayer 22 by a dry film forming method. Forming a coating film 24 containing the base electrode 22, and obtaining a terminal electrode 20 in which the base layer 22 is covered with the coating film 24. This manufacturing method is also a manufacturing method of a ceramic core 100 including a ceramic element body 10 and a terminal electrode 20 on the ceramic element body 10, which is a kind of electronic component. Details of each step will be described below with reference to the drawings as appropriate.

  In the preparation step, the ceramic body 10 for the ceramic core is produced. The ceramic body 10 can be produced by a known method. For example, when the ceramic core 100 is a ferrite core, Ni-Cu-Zn-based, Ni-Zn-based, or Mn-Zn-based ferrite powder, a binder, and additives are mixed and mixed, and heated as necessary. And granulate. The obtained granulated powder is press-molded to produce a molded body, heated to a predetermined temperature and degreased, and then fired to produce a ceramic body 10 for a ferrite core. The firing temperature can be set to 1000 to 1200 ° C., for example, and the firing time can be set to 1 to 3 hours, for example. In the case where the ceramic core 100 is a non-magnetic core, the ceramic body 10 can be produced by a known method using powder such as alumina.

  In the application step, a paste containing the first metal component and the glass component is applied on the ceramic body 10. The paste used here can be prepared by blending a commercially available metal powder containing the first metal component, a glass powder, a binder and a solvent. The first metal component is preferably a metal containing at least one of Ni, Ti, Ag and Cu, or an alloy containing the metal, more preferably an alloy containing Ni or Ni. As the metal powder, a powder containing these metals or alloys can be used.

  Of the first metal components, Ni has an excellent anti-diffusion function, and prevents the metal components (such as Sn) contained in the solder and the coating 24 from diffusing into the ceramic body 10. It can be sufficiently suppressed. Further, as shown in Table 1, Ni has the lowest melting point among the metals considered to have a diffusion preventing function, and therefore, the synergistic action with the use of the glass component causes the firing temperature of the base layer 22 to be formed. Contributes to reduction. Thus, by using the metal powder containing Ni, it is possible to sufficiently suppress the performance degradation of the ceramic body 10 due to the diffusion of metal elements and heat.

  Examples of the Ni alloy used for the first metal component include alloys of Ni and at least one metal element selected from Pd, Pt, Co, Fe, Cr, Ti, W, Mo, and Nb. Such an alloy can sufficiently suppress the diffusion of the metal element from the solder or coating 24 into the ceramic body 10. Further, by using the Ni alloy, it is possible to adjust the firing temperature of the underlayer 22, the shrinkage behavior during firing, the linear expansion coefficient during firing, and the like.

  Since Ag and Cu have a low melting point, when Ag or Cu is used as the first metal component, the firing temperature can be lowered when the underlayer 22 is formed. However, Ag and Cu are more easily diffused than Ni or the like. For this reason, for example, the first metal component may contain Ag and Cu to the extent that the diffusion preventing function of the underlayer 22 is not impaired. Thereby, it is possible to reduce the firing temperature and reduce the resistance of the terminal electrode 20 while maintaining the function of preventing the diffusion of the metal element into the ceramic body 10.

  The content of the first metal component in the paste is preferably 60 to 95% by mass, more preferably 70 to 95% by mass, and still more preferably 80 to 93%, based on the total of the first metal component and the glass component. % By mass. When the content rate of the first metal component becomes too high, the firing temperature of the underlayer 22 tends to increase. On the other hand, if the content of the first metal component is too low, the diffusion preventing function of the underlayer 22 tends to be impaired.

  Although there is no restriction | limiting in particular in the glass powder used for preparation of a paste, A softening temperature becomes like this. Preferably it is 700 degrees C or less, More preferably, it is 600 degrees C or less. By using glass powder having a low softening temperature in this manner, the firing temperature can be lowered, and the oxidation of the first metal component and the performance degradation of the ceramic body 10 can be sufficiently suppressed. As the binder, a resin such as acrylic, butyral, or polyvinyl alcohol can be used. As the solvent, ethanol, xylene, butyl carbitol, terpineol, or the like can be used. The glass powder is preferably made of glass containing an alkali metal oxide from the viewpoint of improving the blasting property in the surface treatment step described later.

  It is preferable that the manufacturing method of this embodiment has a degreasing process of heating and degreasing the paste apply | coated on the ceramic base body between the application | coating process and a baking process. In the degreasing step, the binder contained in the paste is removed by burning in the atmosphere. The heating temperature in the degreasing step varies depending on the type of the binder, and is preferably 300 to 500 ° C, for example.

  In the firing step, the base layer 22 is formed by firing the paste on the ceramic body 10. The atmosphere during firing is an inert gas atmosphere such as nitrogen gas or argon gas as necessary, and the firing temperature is equal to or higher than the softening temperature of the glass powder included in the paste. Specifically, the firing temperature is preferably 500 to 700 ° C, more preferably 550 to 650 ° C. The firing time is preferably 0.1 to 10 hours, more preferably 0.5 to 5 hours. By firing under such firing conditions, it is possible to form the base layer 22 having excellent adhesion while suppressing the performance degradation of the ceramic body 10 due to heat and element diffusion. If the firing temperature is too high, the residual stress in the vicinity of the interface between the ceramic body 10 and the base layer 22 increases, and the ceramic body 10 tends to easily generate cracks or deteriorate adhesion. On the other hand, if the firing temperature is too low, sintering of the underlayer 22 does not proceed sufficiently, and the adhesion between the underlayer 22 and the ceramic body 10 tends to be impaired.

  The thickness of the underlayer 22 is preferably 0.5 to 20 μm, more preferably 2 to 10 μm, and further preferably 3 to 8 μm. If the thickness of the underlayer 22 becomes too small, it tends to be difficult to sufficiently suppress element diffusion from the coating 24. On the other hand, when the thickness of the foundation layer 22 becomes too large, the ceramic core 100 tends to increase in size.

  In the surface treatment step, the surface of the base layer 22 is blasted. In the manufacturing method of this embodiment, since the foundation layer 22 is formed by firing a paste containing glass powder and metal powder, there is glass floating in which glass is deposited on the surface of the foundation layer 22 according to the firing conditions. It may generate | occur | produce and the sufficient adhesiveness of the base layer 22 and a membrane | film | coat may be impaired. Therefore, if the glass existing on the surface of the underlayer 22 is blasted by the surface treatment step, the adhesion between the underlayer 22 and the coating 24 can be improved. The blasting method is not particularly limited, and for example, glass on the surface of the underlayer 22 can be excluded by causing metal particles to collide with the surface of the underlayer 22.

  In the film forming step, the coating 24 containing the second metal component is formed on the base layer 22 by a dry film forming method, and the terminal electrode 20 in which the base layer 22 is covered with the coating 24 is formed. Examples of the dry film forming method include vapor deposition, ion plating, sputtering, CVD, plasma CVD, thermal spraying, and cold spray. In the manufacturing method of this embodiment, since the film 24 is formed by such dry film formation, it is not necessary to attach a plating solution or the like to the ceramic body 10. Therefore, it is possible to prevent the surface of the ceramic body 10 from being corroded by the plating solution and the performance deterioration of the ceramic body 10 due to the penetration of the plating solution or the like.

  The dry film forming method described above can be performed under normal conditions. In order to prevent the film 24 from being formed on the surface of the ceramic body 10 where the underlayer 22 is not formed, the surface of the ceramic body 10 is masked in the case of vapor deposition, ion plating and sputtering. There is a need. On the other hand, in the case of thermal spraying and cold spraying, the coating 24 can be formed only on the base layer 22 without masking by selecting appropriate conditions. For this reason, it is preferable to form a film by thermal spraying and cold spray from the viewpoint of process simplification. In addition, cold spray is most preferable because the above-described surface treatment step and film forming step can be performed simultaneously. That is, according to cold spray, the particle diameter of the metal particles or alloy particles containing the second metal component, the ejection speed from the nozzle, the speed when colliding with the base layer 22 (collision speed), and the working distance (from the ejection port) By adjusting the distance to the underlayer 22, the film 24 can be formed by adhering and depositing particles on the surface of the underlayer 22 while removing the glass deposited on the surface of the underlayer 22. . The cold spray can be performed using a normal cold spray apparatus.

  When the coating 24 is formed on the surface of the undercoat layer 22 by cold spraying, the size of the nozzle for cold spraying and the ejection speed of the particles according to the type of particles to be sprayed, the particle size of the particles, the material of the undercoat layer 22 and the like. It is preferable to adjust the working distance and the like as appropriate. As a kind of particle | grains, the metal particle and alloy particle | grains containing a 2nd metal component can be used.

  The particle size of the particles used for the cold spray is preferably 1 to 30 μm, more preferably 1 to 20 μm, still more preferably 2 to 10 μm, and most preferably 2 to 5 μm. If the particle size is less than 1 μm, it tends to be difficult to accelerate the particles and to ensure the stability of the ejection speed. On the other hand, if the particle diameter exceeds 30 μm, it is difficult to reduce the thickness of the coating 24.

  The smaller the particle size of the particles used for the cold spray, the higher the adhesion efficiency and the better the adhesion with the underlayer 22. From the viewpoint of forming the thin film 24 made of a metal layer having good adhesion, it is preferable to use particles having a particle size as small as possible. Further, the thickness of the metal layer is preferably 0.5 times or more, more preferably 1 or more times the average particle diameter of particles used for cold spray. When the thickness of the metal layer is less than 0.5 times the average particle diameter of the particles, it tends to be difficult to ensure the continuity of the metal layer.

  When the particles to be sprayed are tin particles having a particle size of 1 to 30 μm or alloy particles containing tin, the ejection speed of the particles is preferably 100 to 1000 m / second, and the collision speed is preferably 50 to 800 m / second, more preferably 360 to 800 m / sec. If the impact speed is too high, the underlayer 22 may be scraped. If the impact speed is too low, the plastic deformation of the particles does not proceed sufficiently, and the denseness and uniformity of the coating 24 tend to be impaired. Moreover, the supply amount by cold spray of tin particles or alloy particles containing tin is preferably 1 to 10 g / min. If the supply amount is less than 1 g / min, the uniformity of the coating 24 tends to be impaired. If the supply amount exceeds 10 g / min, the cold spray feeder or the like may be blocked.

  When a tin film or a tin alloy film is formed by cold spraying, the deposition rate of tin or tin alloy on the ceramic body can be made significantly smaller than the deposition rate of tin or tin alloy on the metal. For this reason, if the conditions of cold spray are adjusted, a tin film or a tin alloy film can be formed only on the underlayer 22 without a mask.

  The carrier gas for cold spray is preferably inert and has a low gas density. This is because the smaller the gas density, the larger the volume expansion, and the particles can be easily accelerated. Specifically, helium gas, neon gas, argon gas, nitrogen gas, or a mixed gas thereof can be used.

  According to cold spray, since the film 24 can be formed even at room temperature, the residual stress in the film 24 can be sufficiently reduced as compared with the thermal spraying method. Moreover, since the performance degradation by the heat | fever of the ceramic body 10 can fully be suppressed, and since it is not necessary to attach a plating solution like wet plating, the performance degradation of the ceramic body 10 can be sufficiently suppressed. Can do. Further, the dense film 24 can be efficiently formed regardless of whether the underlying layer 22 is conductive. In addition, if the base layer 22 is heated to such an extent that the ceramic body 10 is not degraded by heat and cold spraying is performed, the adhesion of the coating 24 and the adhesion probability of the particles can be improved.

  The second metal component is different from the first metal component. For example, the second metal component preferably contains a metal containing at least one of Sn and Au, or an alloy containing the metal. For this reason, it is preferable to use metal particles made of such a metal or alloy for forming the coating 24. Moreover, it is more preferable that the above-mentioned 2nd metal component contains Sn or Sn alloy from a viewpoint of improving adhesiveness with solder further. Moreover, Sn is more preferable from the viewpoint of manufacturing cost.

  Examples of the Sn alloy include an alloy of Sn and at least one metal element selected from Pt, Au, Pd, Ag, and Cu. By using such an Sn alloy, the wettability of the solder and the adhesiveness with the solder can be further improved. From the same viewpoint, among the Sn alloys, a component having the same composition as the solder metal is more preferable, and Sn-3.5Ag-0.5Cu is particularly preferable.

  If the coating 24 contains Sn or Sn alloy as the second metal component and the underlayer 22 contains Ni or Ni alloy, element diffusion from the coating 24 to the ceramic body 10 can be sufficiently suppressed. In addition, the performance degradation of the ceramic body 10 can be sufficiently suppressed, and the terminal electrode 20 can be further improved in solder wettability and adhesiveness with solder.

  The thickness of the film 24 is preferably 0.2 to 20 μm, more preferably 1 to 10 μm, and further preferably 2 to 6 μm. If the thickness of the film 24 becomes too small, the solder wettability and the excellent adhesion with the solder tend to be impaired. On the other hand, when the thickness of the film 24 becomes too large, the manufacturing cost increases and the ceramic core 100 tends to be enlarged.

  Through the above-described steps, a ceramic core 100 including the ceramic body 10 and the terminal electrode 20 provided on the surface of one flange 14 of the ceramic body 10 can be obtained. Since this terminal electrode 20 has a structure in which an underlayer containing a first metal component and a glass component and a film containing a second metal component are laminated, the adhesion to the ceramic body 10 is improved. Excellent solder wettability and adhesion to solder.

  The thickness T1 of the terminal electrode 20 is preferably 0.7 to 40 μm, more preferably 3 to 20 μm, and still more preferably 5 to 15 μm. Accordingly, it is possible to obtain the terminal electrode 20 that is more excellent in solder wettability and adhesion to the solder while avoiding an increase in the size of the ceramic core 100.

  Even if the terminal electrode 20 is formed by firing the base layer 22 at a low temperature of 1000 ° C. or lower, the terminal electrode 20 is sufficiently excellent in adhesion to the ceramic body 10. Since it can be fired at such a low temperature, the performance of the ceramic body 10 can be sufficiently maintained. That is, according to the manufacturing method of the present embodiment, it is possible to manufacture a ceramic core that sufficiently suppresses the performance degradation of the ceramic body associated with the formation of the terminal electrode and is excellent in reliability.

  FIG. 3 is a schematic cross-sectional view of a coil component which is a kind of electronic component obtained by the manufacturing method of the present embodiment. The coil component 150 is formed by winding a winding 50 made of a conductive material around the winding core portion 12 of the ceramic core 100 obtained by the above-described manufacturing method, and using the solder 52 for the leading end and the trailing end of the winding. It can be manufactured by connecting to the terminal electrode 20. The coil component 150 may be, for example, a choke coil, a transformer, or a common mode choke coil.

Second Embodiment
FIG. 4 is a perspective view showing a multilayer ceramic capacitor obtained by the manufacturing method of another embodiment of the present invention. The multilayer ceramic capacitor 200 shown in FIG. 4 has a substantially rectangular parallelepiped shape. For example, the length in the longitudinal direction (lateral) is about 2.0 mm, the length in the width direction and the length in the depth direction are 1.2 mm. Degree.

  A multilayer ceramic capacitor 200, which is a kind of multilayer electronic component, includes a substantially rectangular parallelepiped chip element body 1 and a pair of terminal electrodes 20 formed at both ends of the chip element body 1, respectively. The chip body 1 includes an end surface 11a and an end surface 11b (hereinafter collectively referred to as “end surface 11”) facing each other, and side surfaces 13a and 13b (hereinafter collectively referred to as “side surface 13”) perpendicular to the end surface 11 and facing each other. And a side surface 15a and a side surface 15b (hereinafter collectively referred to as “side surface 15”) that are perpendicular to the end surface 11 and face each other. The side surface 13 and the side surface 15 are perpendicular to each other.

  The chip body 1 includes a ridge portion R3 between the end surface 11 and the side surface 13a, a ridge portion R4 between the end surface 11 and the side surface 13b, a ridge portion R5 between the end surface 11 and the side surface 15a, and the end surface 11 and the side surface 15b. And a ridge portion R6 therebetween. The ridges R3 to R6 are portions where the chip body 1 is polished to form an R shape. By having such an R shape, the occurrence of breakage in the ridges R3 to R6 of the chip body 1 can be suppressed. The curvature radius of the ridge portion in the chip body 1 can be set to 3 to 15% of the length in the width direction of the multilayer ceramic capacitor 200, for example.

  The terminal electrode 20 covers the end surface 11, the ridge portion R 3, the ridge portion R 4, the ridge portion R 5, and the ridge portion R 6 of the chip body 1, and also integrally covers a part of the side surfaces 13 and 15 on the end surface 11 side. Is provided. That is, the terminal electrode 20 is provided so as to cover the top portion 42 of the chip body 1.

  FIG. 5 is a cross-sectional view taken along line VV of the multilayer ceramic capacitor 200 of FIG. That is, FIG. 5 is a view showing a cross-sectional structure of the multilayer ceramic capacitor 200 shown in FIG. 4 cut along a plane perpendicular to the side surface 13 and parallel to the side surface 15.

  The terminal electrode 20 has a stacked structure in which a base electrode layer 23 that is a base layer and a coating 24 are sequentially stacked in this order on the end face 11, the ridges R <b> 3 to R <b> 6, and the top 42. . The base electrode layer 23 contains a glass component and a first metal component, and the coating 24 contains a second metal component.

  The chip body 1 is configured by alternately laminating a plurality of dielectric layers 7 and a plurality of internal electrodes 9 which are ceramic bodies. The stacking direction is perpendicular to the facing direction of the pair of end surfaces 11 on which the terminal electrodes 20 are provided, and is parallel to the facing direction of the pair of side surfaces 13. For convenience of explanation, in FIG. 5, the number of laminated dielectric layers 7 and internal electrodes 9 is set so as to be easily visible on the drawing, but depending on the desired electrical characteristics, the dielectric layers 7 and The number of stacked internal electrodes 9 may be changed as appropriate. The number of stacked layers may be, for example, several tens of the dielectric layers 7 and internal electrodes 9 or about 100 to 500 layers. Moreover, the dielectric material layer 7 may be integrated so that the boundary between each other cannot be visually recognized.

  The internal electrode 9a is electrically connected to the terminal electrode 20 on the one end face 11a side, and is electrically insulated from the terminal electrode 20 on the other end face 11b side. The internal electrode 9b is electrically connected to the terminal electrode 20 on the other end face 11b side, and is electrically insulated from the terminal electrode 20 on the one end face 11a side. The internal electrodes 9a and the internal electrodes 9b are alternately stacked with the dielectric layer 7 interposed therebetween. The multilayer ceramic capacitor 200 of this embodiment is excellent in the insulation reliability between the terminal electrode 20 on the end face 11a side and the internal electrode 9b, and the insulation reliability between the terminal electrode 20 on the end face 11b side and the internal electrode 9a.

  The manufacturing method of this embodiment is a manufacturing method of the terminal electrode 20 provided on the end surface 11 and the side surfaces 13 and 15 of the chip body 1 for the multilayer ceramic capacitor, and the chip body 1 is manufactured. A preparatory step, a coating step of applying a paste containing a first metal component and a glass component onto a part of the end surface 11 and the side surfaces 13 and 15 of the chip body 1, and the end surface 11 of the chip body 1 and On the base electrode layer 23, a baking process for baking the paste applied on a part of the side surfaces 13 and 15 to form the base electrode layer 23, a surface treatment process for blasting the surface of the base electrode layer 23, and Forming a film 24 containing a second metal component by a dry film forming method, and obtaining a terminal electrode 20 in which the base electrode layer 23 is covered with the film 24. That is, the manufacturing method of this embodiment is also a manufacturing method of the multilayer ceramic capacitor 200. Details of each step will be described below with reference to the drawings as appropriate.

  In the preparation step, the chip body 1 is manufactured by a normal method as described below. First, a ceramic green sheet to be the dielectric layer 7 is formed. The ceramic green sheet can be formed by applying a ceramic slurry on a PET film using a doctor blade method or the like and then drying it. The ceramic slurry can be obtained, for example, by adding a solvent, a plasticizer, and the like to a dielectric material mainly composed of barium titanate and mixing them. An electrode pattern to be the internal electrode 9 is screen-printed on the formed ceramic green sheet and dried. For the screen printing of the electrode pattern, an electrode paste obtained by mixing a binder or a solvent with Cu powder or Ni powder can be used.

  In this manner, a plurality of green sheets with electrode patterns are formed and laminated. Subsequently, the stacked body of green sheets with electrode patterns is cut perpendicularly to the stacking direction to form a rectangular parallelepiped stacked chip, and heat treatment is performed to remove the binder. The heat treatment is preferably performed at 180 to 400 ° C. for 0.5 to 30 hours. The laminated chip obtained by the heat treatment is baked at 800 to 1400 ° C. for 0.5 to 8.0 hours, barrel-polished to be chamfered, and the rectangular parallelepiped ridge is made into an R shape. Thereby, the chip body 1 can be obtained.

  In the application step, a paste containing the first metal component and the glass component is applied on the end surface 11 of the chip body 1 and on a part of the side surfaces 13 and 15 on the end surface 11 side. The same paste as in the first embodiment can be used.

  In the firing step, the base electrode layer 23 is formed by firing the paste applied on the end surface 11 and the side surfaces 13 and 15 of the chip body 1. In this case, the base electrode layer 23 has a function of ensuring electrical continuity between the internal electrode 9 and the terminal electrode 20. The firing temperature is equal to or higher than the softening temperature of the glass component contained in the paste, and is a temperature at which the first metal component contained in the paste can be sufficiently sintered to reduce the electrical resistance of the base electrode layer 23. It is preferable to do. The atmosphere during firing can be the same as in the first embodiment. As a result, it is possible to form the base electrode layer 23 excellent in adhesion and electrical conductivity with the internal electrode 9 while suppressing a decrease in performance of the dielectric layer 7 in the chip body 1 due to heat and element diffusion.

  The thickness of the base electrode layer 23 is preferably 0.5 to 20 μm, more preferably 2 to 10 μm, and further preferably 3 to 8 μm. If the thickness of the base electrode layer 23 becomes too small, it tends to be difficult to sufficiently suppress element diffusion from the coating 24 produced in the process described later. On the other hand, when the thickness of the base electrode layer 23 becomes too large, the monolithic ceramic capacitor 200 tends to increase in size.

  In the surface treatment step, the surface of the base electrode layer 23 is blasted. In the manufacturing method of this embodiment, since the base electrode layer 23 is formed by firing a paste containing glass powder and metal powder, glass on which glass is deposited on the surface of the base electrode layer 23 according to the firing conditions. In some cases, floating occurs, and sufficient adhesion and electrical conductivity between the base electrode layer 23 and the film may be impaired. Therefore, if the glass existing on the surface of the base electrode layer 23 is blasted by the surface treatment step, the adhesion and electrical conductivity between the base electrode layer 23 and the film 24 can be improved. The area covered with glass on the basis of the entire surface of the base electrode layer 23 is preferably 10% or less from the viewpoint of improving adhesion and electrical conductivity. The blasting method is not particularly limited. For example, glass on the surface of the base electrode layer 23 can be eliminated by causing metal particles to collide with the surface of the base electrode layer 23.

  The surface of the base electrode layer 23 can be roughened by the blast described above. Thereby, the adhesion between the base electrode layer 23 and the coating 24 containing the second metal component can be improved. The surface roughness of the base electrode layer 23 is preferably 0.3 to 5 μm in Ra (center line average roughness). When Ra is 0.3 μm or less, the effect of improving the adhesion between the base electrode layer 23 and the film 24 tends to be insufficient. On the other hand, when Ra is 5 μm or more, the continuity of the base electrode layer 23 tends to be easily lost.

  As for the structure of the base electrode layer 23, it is preferable that the glass coating area of the surface on the side of the film 24 is 10% or less of the entire surface, and the surface roughness Ra is 0.3 to 5 μm. In these, the base electrode layer 23 having the above-described structure can be easily formed by appropriately setting the blasting conditions. From the viewpoint of improving the adhesion at the interface between the base electrode layer 23 and the chip body 1 (ceramic body), the base electrode layer 23 may increase the glass component content within a range that does not impair electrical conductivity. preferable. That is, it is preferable that the interface between the base electrode layer 23 and the chip body 1 has a higher glass coating area ratio than the interface between the base electrode layer 23 and the coating 24 containing the second metal component.

  In the film forming step, the coating 24 containing the second metal component is formed on the base electrode layer 23 by a dry film forming method, and the terminal electrode 20 in which the base electrode layer 23 is covered with the coating 24 is formed. As a dry film forming method, the same method as in the first embodiment can be employed. Therefore, corrosion of the chip body 1 due to penetration of the plating solution or the like can be prevented. In this case, it is preferable to select a dry method that does not generate hydrogen during film formation. When hydrogen is generated in the film forming process, hydrogen is occluded in the ceramic body of the chip body 1 and may cause deterioration of electrical characteristics such as IR reduction. For this reason, when using the CVD method, it is preferable to use a raw material that does not generate hydrogen during film formation.

  The thickness of the film 24 is preferably 0.2 to 20 μm, more preferably 1 to 10 μm, and further preferably 2 to 6 μm. If the thickness of the film 24 becomes too small, the solder wettability and the excellent adhesion with the solder tend to be impaired. On the other hand, if the thickness of the film 24 becomes too large, the manufacturing cost increases and the monolithic ceramic capacitor 200 tends to increase in size.

  The multilayer ceramic capacitor 200 including the chip body 1 and the terminal electrodes 20 provided on part of the end face 11 and the side surfaces 13 and 15 of the chip body 1 can be obtained by the above-described steps. Since this terminal electrode 20 has a structure in which a base electrode layer 23 containing a first metal component and a glass component and a film containing a second metal component are laminated, the terminal electrode 20 Excellent adhesion, solder wettability and adhesion to solder.

  The thickness T1 of the terminal electrode 20 is preferably 0.7 to 40 μm, more preferably 3 to 20 μm, and still more preferably 5 to 15 μm. As a result, it is possible to obtain a terminal electrode 20 that is more excellent in solder wettability and adhesion to solder while avoiding an increase in the size of the multilayer ceramic capacitor 200.

  Since the terminal electrode 20 is sufficiently excellent in adhesion even when fired at a low temperature of 1000 ° C. or lower, the performance of the dielectric layer 7 can be sufficiently maintained. That is, according to the manufacturing method of the present embodiment, it is possible to manufacture a multilayer ceramic capacitor excellent in reliability by sufficiently suppressing the performance degradation of the dielectric layer 7 due to the formation of the terminal electrode.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. In each said embodiment, although the ceramic core, the coil component, and the multilayer ceramic capacitor were mentioned as an electronic component, the manufacturing method of this invention is not limited to the above-mentioned electronic component. The manufacturing method of the present invention can also be applied to a manufacturing method of electronic parts such as a varistor including a ceramic sintered body, a thermistor (PTC, NTC), an inductor, or a composite part thereof. These electronic components may be a single layer, or may be stacked electronic components as in the second embodiment described above. Depending on the electronic component to be manufactured, a magnetic body or a dielectric can be appropriately used as the ceramic body.

  In the production method of the present invention, the surface treatment step is not necessarily performed, and the film-controlling step and the surface treatment step may be performed simultaneously. Further, a layer made of another material may exist between the ceramic body and the base layer, or between the base layer and the coating. Moreover, it is good also as a terminal electrode which has the laminated structure which repeated manufacture of the base layer and the film | membrane several times, and laminated | stacked the several base layer and the some film.

  The contents of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]
<Formation of terminal electrode>
A drum-type ceramic body made of Ni—Cu—Zn ferrite as shown in FIG. 1 was prepared. Separately, commercially available nickel powder (average particle size: 1 μm) and commercially available glass powder (average particle size: 1 μm, softening temperature: 550 ° C.) are mixed, and the mass of the nickel powder relative to the glass powder. A mixed powder having a ratio of 9.0 was obtained. To this was added a binder (polyvinyl alcohol) and a solvent to prepare a paste.

  The paste prepared as described above was applied to a predetermined portion of the ceramic body, and fired at 600 ° C. in the atmosphere to form a base layer having a thickness of 5 μm on the surface of the ceramic body.

  The surface of the ceramic body on which the underlayer is not formed is masked with Kapton tape, and tin particles collide with the underlayer formed on the surface of the ceramic body by cold spraying. Then, a tin film having an average film thickness of 5 μm was formed. Cold spraying was performed under the following conditions.

・ Carrier gas: He gas ・ Gas pressure: 0.5 MPa
-Average particle size of tin particles: 20 μm
-Tin particle supply rate: 2 g / min-Tin particle ejection speed: 400 m / sec-Work temperature: Room temperature (about 20 ° C)
・ Scanning speed (500mm / sec)

  Through the above steps, a terminal electrode made of a base layer and a tin film covering the base layer was formed on the ceramic body, and a ferrite core as shown in FIG. 1 was obtained. The same production was repeated to produce 20 ferrite cores on which terminal electrodes were formed.

<Evaluation>
(Evaluation of solder wettability)
On a printed circuit board having electrodes, 20 ferrite cores on which terminal electrodes are formed are used with lead-free solder (Senju Metal Industry, trade name: Ecosolder M705, composition: Sn-3.5Ag-0.5Cu). The sample for evaluation was produced by mounting it. Using this evaluation sample, the solder wettability was visually evaluated according to the following criteria.

A: The solder wettability was good, and a smooth fillet could be formed between the ferrite core terminal electrode and the printed circuit board electrode.
B: The solder wettability was poor, and a smooth fillet could not be formed between the ferrite core terminal electrode and the printed circuit board electrode.

  As a result, the evaluation of all 20 samples was “A”, and it was confirmed that the terminal electrode in the ferrite core of Example 1 was excellent in solder wettability.

(Evaluation of terminal electrode reliability)
After conducting the solder wettability evaluation described above, a lateral pressing test was performed to apply a lateral force (direction perpendicular to the opposing direction of the printed circuit board and the ferrite core) to the ferrite core mounted on the printed circuit board. The fracture location when it occurred was evaluated according to the following criteria.

A: The ferrite core itself was broken.
B: Between the solder and the terminal electrode or the terminal electrode peeled from the ceramic body.

  The ferrite core evaluated as “A” has high adhesion between the solder and the terminal electrode and between the ceramic body and the terminal electrode, and is excellent in reliability. On the other hand, the ferrite core evaluated as “B” has low adhesion between the solder and the terminal electrode or the ceramic body and the terminal electrode, and is less reliable than the ferrite core evaluated as “A”. As a result of the evaluation, all 20 samples were evaluated as “A”, and it was confirmed that the terminal electrode of the ferrite core of Example 1 was excellent in reliability.

[Comparative Example 1]
On the surface of the ceramic body in the same manner as in Example 1, except that the base layer was formed on the ceramic body in the same manner as in Example 1 using a paste containing no glass powder and containing nickel powder. An underlayer having a thickness of 5 μm was formed. Then, masking made of Kapton tape was applied to the surface of the ceramic body on which the underlayer was not formed. Thereafter, in the same manner as in Example 1, when the tin particles were made to collide with the base layer formed on the surface of the ceramic body by cold spray, the base layer was peeled off from the ceramic body. For this reason, the terminal electrode could not be formed on the ceramic body.

[Comparative Example 2]
A terminal electrode was formed in the same manner as in Example 1 except that the base layer was not formed. The adhesion ratio of tin particles to the ferrite core by cold spray (ratio to the total amount of tin particles supplied by cold spray) was 5% by mass, and a terminal electrode having a sufficient thickness could not be formed. In addition, a part of the ceramic body was etched by 100 μm or more by cold spray.

[Comparative Example 3]
Instead of forming a tin film by the cold spray method, a nickel plating film and a tin plating film are sequentially formed on the base layer by a wet plating (barrel plating) method, and the base layer is formed on the ceramic body. A terminal electrode comprising a plating film covering the underlayer was formed. The ratio of the area of the base layer on which the plating film was formed was 10% or less on the basis of the entire surface area of the base layer subjected to the plating treatment, and a uniform plating film could not be formed. This is considered to be the influence of the glass on the surface of the underlayer caused by the glass floating of the underlayer.

[Example 2]
A ferrite core was obtained by forming a terminal electrode on the ceramic body in the same manner as in Example 1 except that a commercially available titanium powder was used instead of the nickel powder. Then, evaluation samples were prepared and evaluated in the same manner as in Example 1. As a result, the evaluation of solder wettability and reliability was “A” for all 20 samples.

[Example 3]
In the same manner as in Example 1, except that alloy particles having a composition of Sn-3.5Ag-0.5Cu were used instead of tin particles as metal particles used in the cold spray method, A terminal electrode composed of a base layer and an alloy film covering the base layer was formed to obtain a ferrite core. Then, evaluation was performed in the same manner as in Example 1. As a result, the evaluation of solder wettability and reliability was “A” for all 20 samples.

[Example 4]
<Formation of terminal electrode>
The chip body has a predetermined dimension (vertical 1 mm × width 0.5 mm × thickness 0.5 mm), and nickel electrode layers and ceramic element layers that are internal electrodes are alternately stacked on both ends of the chip element body. A paste containing nickel powder and glass powder used in Example 1 was applied and baked at 600 ° C. in the atmosphere to form a base electrode layer containing nickel and glass having a thickness of 5 μm.

  On this base electrode layer, a tin film having a thickness of 4 μm is formed by a cold spray method in the same manner as in Example 1, and the base electrode layer and the tin film covering the base electrode layer are formed on both ends of the chip body. A terminal electrode consisting of the following was formed to obtain a multilayer ceramic capacitor. In addition, since cold spraying was performed without masking, the tin particles collided with the surface of the chip body on which the base electrode layer was not formed, but the tin particles did not adhere to the surface of the chip body.

<Evaluation>
(Evaluation of solder wettability)
20 multilayer ceramic capacitors were mounted on a printed circuit board having electrodes using lead-free solder (trade name: Ecosolder M705, composition: Sn-3.5Ag-0.5Cu) manufactured by Senju Metal Industry. An evaluation sample was produced. After mounting, the solder wettability was visually evaluated according to the following criteria.

A: The solder wettability was good, and a smooth fillet could be formed between the terminal electrode of the multilayer ceramic capacitor and the electrode of the printed board.
B: The solder wettability was poor, and a smooth fillet could not be formed between the terminal electrode of the multilayer ceramic capacitor and the electrode of the printed circuit board.

  As a result, the evaluation of all 20 samples was “A”, and it was confirmed that the terminal electrode of the multilayer ceramic capacitor of Example 4 was excellent in solder wettability.

(Evaluation of IR characteristics)
In the same procedure, 1000 multilayer ceramic capacitors were produced and the occurrence rate of insulation failure was evaluated. Specifically, one having a resistance between internal electrodes of 1 × 10 ⁹ Ω or less was determined as a defective product. As a result, out of 1000 multilayer ceramic capacitors, there were 0 defective products.

[Comparative Example 4]
In the same manner as in Example 4, base electrode layers containing nickel and glass were formed on both ends of the chip body. The surface of the base electrode layer is blasted to remove the glass deposited on the surface of the base electrode layer, and a 4 μm thick tin plating film is formed on the base electrode layer by wet plating (neutral Sn plating). And the terminal electrode which consists of a base electrode layer and the tin plating film which covers this base electrode layer was formed in the both ends of a chip | tip body, and the multilayer ceramic capacitor was obtained.

  In the same manner as in Example 4, solder wettability and IR characteristics were evaluated. As a result, the solder wettability was evaluated as “A” for all 20 samples, but in the evaluation of IR characteristics, 7 defective products were generated out of 1000 multilayer ceramic capacitors.

  In Comparative Example 4, since blasting was performed, a tin plating film was formed on the entire surface of the base electrode and had good solder wettability. However, it is considered that due to factors such as blasting, cracks or the like occurred in the base electrode layer, and the plating solution entered from the cracks during wet plating, resulting in poor insulation. Therefore, it was confirmed that the terminal electrode of the multilayer ceramic capacitor of Example 4 had higher reliability than the terminal electrode of Comparative Example 4.

  DESCRIPTION OF SYMBOLS 1 ... Chip body, 7 ... Dielectric layer, 9, 9a, 9b ... Internal electrode, 10 ... Ceramic body, 11, 11a, 11b ... End surface, 12 ... Core part, 13, 15 ... Side surface, 14 ... 鍔, 16 ... peripheral side, 18 ... end face, 20 ... terminal electrode, 22 ... base layer, 23 ... base electrode layer, 24 ... coating, 42 ... top, 50 ... winding, 52 ... solder, 100 ... ferrite core, 150 ... coil parts, 200 ... multilayer ceramic capacitors.

Claims (6)

An application step of applying a paste containing a first metal component and a glass component on a ceramic body for an electronic component;
A firing step of firing the paste on the ceramic body to form an underlayer;
A terminal electrode having the coating for covering the base layer and the base layer by forming a film containing a second metal component different from the first metal component on the base layer by a dry film forming method. And a film forming step for obtaining a terminal electrode.   The manufacturing method of the terminal electrode of Claim 1 which has the surface treatment process of blasting the surface of the said base layer after the said baking process.   The terminal electrode manufacturing method according to claim 1, wherein the dry film forming method is a cold spray method.   4. The method for manufacturing a terminal electrode according to claim 1, wherein the first metal component contains a metal containing at least one of Ni, Ti, Ag, and Cu, or an alloy containing the metal. 5. .   5. The method of manufacturing a terminal electrode according to claim 1, wherein the second metal component contains a metal containing at least one of Sn and Au, or an alloy containing the metal. An application step of applying a paste containing a first metal component and a glass component on the ceramic body;
A firing step of firing the paste on the ceramic body to form an underlayer;
Forming a film containing a second metal component on the base layer by a dry film forming method to obtain a terminal electrode having the base layer and the film covering the base layer; A method of manufacturing an electronic component comprising the ceramic body and the terminal electrode.

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