JP5164024B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component.

  In recent years, there has been a demand for further downsizing, thinning, and high-density mounting of electronic devices. Active components such as semiconductor devices such as IC chips used in electronic devices, and passive components such as capacitors, inductors, thermistors, resistors, etc. Similarly, miniaturization and thinning of circuit boards on which electronic components such as these are mounted are also eagerly desired.

  Among these electronic components, especially for ceramic chip capacitors that are multilayer (type) ceramic electronic components, there is a strong demand from the market not only for miniaturization and thinning, but also for higher capacities. . On the other hand, in order to meet the demand for high-density mounting, the mounting area of electronic components cannot be increased, so in ceramic chip capacitors, the dielectric and internal electrodes are rapidly becoming thinner. For example, even in the C2012 size (outer dimensions 2.0 mm × 1.2 mm × 1.2 mm), the number of stacked layers exceeding 800 layers is on the market. In addition, there is a tendency to reduce the mounting area of the electronic component on the circuit board. Surface mount multilayer ceramic capacitors have been developed that have external terminals and terminals and are externally connected from both sides in the stacking direction.

As such a type of multilayer ceramic electronic component, for example, in Patent Documents 1 to 4, a plurality of dielectric ceramic layers are stacked, and an internal electrode made of a sintered body of a conductive material is formed between the layers. Furthermore, there has been proposed a multilayer ceramic electronic component (capacitor) provided with a via conductor made of a sintered body of a conductor material so as to connect internal electrodes. In other words, in these, patterns of dielectric ceramic layers and internal electrodes are alternately laminated, and internal electrodes arranged opposite to each other through the dielectric ceramic layers are connected by via electrodes penetrating the dielectric ceramic layers. Is.
JP 2002-359139 A JP 2005-136231 A JP 2003-151851 A JP 2002-344140 A

  By the way, the above-mentioned conventional multilayer ceramic electronic component is obtained by laminating a plurality of ceramic green sheets for forming a dielectric ceramic layer and a conductor material layer for forming internal electrodes to obtain a multilayer body, and then via electrodes on the multilayer body. After forming via holes (through holes) for formation and filling the via holes with conductive paste for forming via electrodes (via fill), or whenever a ceramic green sheet and a conductor material layer are laminated, the via holes are formed. It is manufactured by filling the conductive paste for forming the via electrode, forming the laminated body by repeating the process (single-wafer method), and firing the laminated body. In that case, as a method of drilling a via hole, laser processing (laser ablation), machining by micro drilling or punching, and the like can be mentioned.

  However, in the case of forming a via hole using a micro drill, in the conventional method for manufacturing a multilayer ceramic electronic component, the method of drilling a via hole after forming the laminate and the single wafer method are both before firing. Soft ceramic green sheets and conductive material layers (both usually containing an organic binder (resin), solvent, etc.) will be drilled, so some of the green ceramic will be drilled (by micro-drill) It is easy to attach to the outer surface of the micro drill. When the microdrill is rolled in this state, the drill residue is stretched to the inner wall of the via hole in which the drill residue is drilled, and a dielectric film is formed. As a result, the conduction between the via electrode embedded in the via hole and the internal electrode is established. There is a risk that the reliability and yield of the multilayer ceramic electronic component to be finally manufactured will be reduced.

  Therefore, the present invention has been made in view of such circumstances, and a via hole is formed using a micro drill in a laminate of a ceramic green sheet layer for forming a dielectric ceramic layer and an internal electrode green sheet layer for forming an internal electrode. In this case, the generation of drill debris can be suppressed, thereby preventing the conduction between the via electrode filled in the via hole and the internal electrode can be prevented, thereby improving the reliability and productivity of the product. It is an object of the present invention to provide a method for manufacturing a multilayer ceramic electronic component capable of processing.

  In order to solve the above-mentioned problems, the present inventor has eagerly studied paying attention to the process conditions of the production process of the multilayer ceramic electronic component, and has solved the above problems by a simple method for controlling the state of the green sheet laminate. The inventors have found that this can be solved and have reached the present invention. That is, the method for manufacturing a multilayer ceramic electronic component according to the present invention includes at least one ceramic green sheet layer including a ceramic material for forming a dielectric layer and at least one internal electrode green sheet layer including a conductor material for forming an internal electrode. A first step of forming a laminated body, a second step of applying a heat treatment to the laminated body to form a laminated body that is solidified and dried more than the laminated body before the heat treatment, and the solidified and dried A third step of forming a via hole penetrating the laminated body using a micro drill, a fourth step of filling a via hole with a conductive material for forming a via electrode, and filling the via hole with a conductive material for forming an electrode And a fifth step of firing the laminated body.

  In the method for manufacturing a multilayer ceramic electronic component having such a structure, in the first step, a ceramic green sheet layer for forming a dielectric layer and an internal electrode green sheet layer containing a conductor material for forming an internal electrode are stacked. In the third step, a via hole for filling a via electrode is drilled in the obtained laminate using a micro drill. At that time, before the via hole is formed, in the second step, the laminate of the green sheet layers is subjected to heat treatment. Thus, the organic binder and solvent contained in the green sheet layer are removed and removed (debinder) according to the amount of heat applied, solidified and dried, and the laminate is hardened as compared to before heat treatment. When drilling a via hole, a part of the green sheet layer is prevented from adhering to the outer surface of the micro drill as a drill residue. As a result, the ceramic film is prevented from being deposited on the inner wall of the via hole, and in the multilayer ceramic electronic component obtained through the fourth and fifth steps, conduction between the via electrode and the internal electrode is hindered. Is effectively suppressed.

  Further, as described above, as a method for forming a via hole, there is a machining process using laser machining or a mechanical punch in addition to using a micro drill. However, in the case of laser processing, the thicker the laminate, the easier it is to scatter the laser light, and the smaller the effective beam diameter of the laser that irradiates the surface of the laminate, the smaller the depth (in the deep part) of the via hole. In this case, it becomes difficult to form a via hole having a sufficiently large aspect ratio. In this respect, machining with a micro drill is advantageous.

  On the other hand, in the case of mechanical processing by mechanical punch, although there is no drawback in the laser processing described above, in a hard state in which the green sheet laminate is solidified and dried by heat treatment, the laminate is more fragile than before heat treatment. Therefore, in machining such as a mechanical punch to which an impact load is applied at a time, cracks are likely to occur in the laminate. In addition, an event such as bending of the laminate or the punch itself may occur, and in this respect, the practicality is inferior. On the other hand, since machining with a micro drill is excavation with a rotary blade, even if the laminated body is solidified and dried and hardened to some extent, an impact load as with a mechanical punch is not applied. Generation | occurrence | production of the phenomenon that a crack arises in a body or a laminated body and a punch bend can be prevented.

  Further, in the second step, if the laminated body is heat-treated so that the Vickers hardness is 20 HV or more, compared to the case where the laminated body is not heat-treated as in the prior art, the via electrode and the internal electrode This is preferable because it makes it easier to significantly improve the conduction characteristics. Further, when the laminated body is heat-treated so that the Vickers hardness of the laminated body is 35 HV or higher, the conduction between the via electrode and the internal electrode is almost certainly ensured. Since it is possible, it is more preferable.

  Here, “Vickers hardness” is a quotient obtained by dividing the test load when a pyramid-shaped depression (indentation) is made on a test piece using a diamond indenter by the surface area obtained from the diagonal length of the depression. Can be used to calculate. At that time, since the shape of the indentation is similar even if the test load changes, there is no difference in the calculated value of Vickers hardness. However, the Vickers hardness in this specification is obtained when a 50 g test load is applied. The value calculated for was used.

  In the second step, it is more preferable to heat-treat the laminate so that the Vickers hardness is 55 HV or less.

  As described above, when the via hole is drilled in the laminate using a micro drill, the drill debris is caused by the softness of the laminate due to the organic binder, solvent, etc. of the green sheet layer. Therefore, for example, it is conceivable to form a via hole by sintering a sintered body of the green sheet layer and hardening it, and then excavating the sintered body with a micro drill. However, according to the inventor's knowledge, when such a hard sintered body is excavated, the structure of the dielectric ceramic layer formed from the ceramic green sheet layer is very strong, so the processing speed is not limited. However, the wear of the micro drill becomes intense and it cannot withstand practical use sufficiently. In addition, since the surface of the sintered body is very hard, the micro drill is repelled on the surface, and the position accuracy of the formed via hole may be lowered due to the excavation position being shifted.

  On the other hand, it is confirmed that by performing the heat treatment of the laminated body so that the Vickers hardness is 55 HV or less, it is possible to sufficiently suppress the misalignment of the via hole considered to be due to the micro drill repelling as described above. It was done.

  Furthermore, it includes a sixth step of forming a cap layer having a smaller hardness than that of the laminated body on the outermost layer of the laminated body that has been solidified and dried before the third step, and in the third step, It is useful to use a micro drill to form a via hole that penetrates the laminate on which the cap layer is formed and solidified and dried. Such a cap layer can be appropriately removed after the via hole is formed.

  In this way, since the hardness of the surface of the laminate can be adjusted by the cap layer, even if the Vickers hardness of the solidified and dried laminate is greater than 55 HV, the hardness of the laminate as a cap layer By using a material that is smaller than the laminated body, it becomes easy to suppress the positional deviation of the via hole that may be caused by the above-described microdrilling. Moreover, if the cap layer is formed as the outermost layer of the laminate, it is possible to prevent the drill residue of the laminate from adhering to the surface of the laminate.

  The “hardness” for comparing the hardness of the laminate and the cap layer may be the above-mentioned Vickers hardness, or as other hardness, indentation hardness, scratch hardness, rebound hardness Both of them may be compared. More specifically, for example, plastic deformation hardness, Brinell hardness, Knoop hardness, Rockwell hardness, superficial hardness, Meyer hardness, durometer hardness. , Barcol hardness, Monotron hardness, Martens hardness, Shore hardness.

  Further, the cap layer is not particularly limited as long as it has a hardness smaller than that of the laminated body, but it may cause dirt adhesion due to the rotational entrainment of the micro drill, so the ceramic green sheet layer or the inner part constituting the laminated body It is more preferable to use a material made of the same kind of material as the matrix component (ceramic, conductor) of the electrode green sheet layer, or a material (for example, a bake plate) that is unlikely to be entangled by a micro drill.

  Alternatively, as the cap layer, it is more preferable to form a layer containing a grindstone component or a layer containing a metal component.

  Usually, due to the excavation of the laminated body, a portion of the cut ceramic green sheet layer or internal electrode green sheet layer is accumulated in the groove of the micro drill, and the excavation performance during continuous use may change. is there. On the other hand, when a layer containing a grindstone component (abrasive grain content) or a layer containing a metal component is formed as a cap layer, the drill residue accumulated in the groove of the microdrill is easily removed and removed due to their dressing effect. Become.

  Further, a seventh step is performed between the third step and the fourth step, and a laminated body in which the dielectric layer and the internal electrode are formed is obtained by performing a baking treatment on the laminated body in which the via hole is formed. In the fourth step, the via hole in the laminate in which the dielectric layer and the internal electrode are formed is filled with a conductive material for forming the via electrode, and in the fifth step, the conductive material is inside the via hole. The via electrode may be formed by firing the laminated body filled in the substrate.

  In such a case, a firing process is performed once in a state in which the via hole is formed in the laminate of the green sheet layers, that is, before the via hole is filled with the conductor material for forming the via electrode. For example, the firing treatment is performed for a predetermined time at a firing temperature necessary for sintering the ceramic green sheet layer in a reducing atmosphere in order to prevent oxidation of the internal electrode green sheet layer after removing the binder as necessary. Further, if necessary, a reoxidation treatment for reoxidizing the formed dielectric layer can be performed.

  The via hole of the sintered body thus obtained is filled with a conductive material for forming a via electrode and baked (in other words, fired again), whereby the conductive material in the via hole is baked to form a via. A multilayer ceramic electronic component having electrodes formed thereon is obtained. At this time, since the ceramic green sheet layer is already fired and becomes a dielectric layer which is a sintered body, the baking temperature is set to be lower than the melting point of the conductor material sufficiently lower than the firing temperature of the ceramic green sheet layer. In this way, the degree of expansion and contraction of the dielectric layer can be kept sufficiently small. Therefore, even if the conductive material for forming the via electrode is baked in this state, the difference in relative expansion and contraction (stretching behavior) between the dielectric layer and the internal electrode and the via electrode is reduced. It is effectively prevented that the body layer, the internal electrode, and the via electrode are separated and a gap is generated between them.

  In addition, since the conductor material for forming the via electrode can be baked at a sufficiently low temperature as compared with the firing temperature of the ceramic layer, the conductor material for forming the internal electrode and the via electrode, and the dielectric layer The relative expansion and contraction behavior with the material of the forming ceramic green sheet layer can be reduced, and as a result, structural defects such as cracks in the dielectric layer and delamination are sufficiently suppressed.

  According to the method for producing a multilayer ceramic electronic component of the present invention, the multilayer body is solidified and dried by applying heat treatment to the multilayer body before the via hole is formed in the multilayer body of the green sheet layer. Therefore, when a via hole is drilled with a micro drill, it is possible to prevent a part of the green sheet layer from becoming a dust residue and sticking to the outer surface of the micro drill. As a result, it is possible to prevent the conduction between the via electrode filled in the via hole and the internal electrode from being hindered, thereby improving the reliability and productivity of the multilayer ceramic electronic component product.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. Further, the following embodiments are exemplifications for explaining the present invention, and are not intended to limit the present invention only to the embodiments. Furthermore, the present invention can be variously modified without departing from the gist thereof.

  FIG. 1 is a sectional view showing a schematic structure of an example of a multilayer ceramic electronic component obtained by using the method for manufacturing a multilayer ceramic electronic component according to the present invention. The multilayer ceramic capacitor 1 (multilayer ceramic electronic component) is a so-called surface-mount type multilayer ceramic capacitor, in which patterns of a plurality of dielectric layers 11 and a plurality of internal electrodes 12 are alternately stacked. Of these, every other layer that is spaced and opposed via each dielectric layer 11 is connected by a via electrode 14 provided so as to penetrate the dielectric layer 11 in the stacking direction. In addition, external connection pads 16 are connected to both ends of each via electrode 14. Bumps and the like may be formed on the external connection pads 16 as necessary.

  In the drawing, a plurality of dielectric layers 11 are described as separate layers. However, as will be described later, these are the ceramic green sheet layers 2 that are precursor layers of the dielectric layers 11 in the manufacturing process. A multi-layered product is formed by firing treatment, and is integrally sintered by firing to constitute the dielectric layer 10 as a whole.

  Next, an example of a method for manufacturing the multilayer ceramic capacitor 1 according to the present embodiment will be described. 2 and 3 are process diagrams showing a part of an example of a procedure for manufacturing the multilayer ceramic capacitor 1.

First, a ceramic powder containing a barium titanate (BaTiO ₃ ) -based ceramic for forming the dielectric layer 11 is prepared. The dielectric layer 11 contains barium titanate as a main component, and further contains a sintering aid component and other subcomponents. More specifically, for example, it contains barium titanate as a main component and at least one or more selected from magnesium oxide, yttrium oxide, dysprosium oxide, and holmium oxide as subcomponents. Furthermore, as other subcomponents, at least one selected from barium oxide, strontium oxide, and calcium oxide, at least one selected from silicon oxide, manganese oxide, and chromium oxide, vanadium oxide, oxidation It may contain at least one selected from molybdenum and tungsten oxide.

As a method for preparing the ceramic powder for the dielectric layer 11 having such a composition, for example, Ba _1.005 TiO ₃ manufactured by a hydrothermal synthesis method is _added to (MgCO ₃ ) ₄ .Mg (OH) ₂ .5H ₂ O, MnCO. ₃ , BaCO ₃ , CaCO ₃ , SiO ₂ , Y ₂ O ₃ , V ₂ O ₅ are added and wet mixed by a ball mill for about ten hours or more. As a final composition, Ba _1.005 TiO ₃ is mixed with MgO, MnO, Y ₂ A method of obtaining a raw material powder containing O ₃ , (Ba _0.6 , Ca _0.4 ) SiO ₃ , and V ₂ O ₅ can be used. As an example of the composition, Ba _1.005 TiO ₃ , MgO: 0.5 mol%, MnO: 0.4 mol%, Y ₂ O ₃ : 1.0 mol%, (Ba _0.6 , Ca _0.4 ) SiO ₃ : 1.0 mol% V ₂ O ₅ : 0.05 mol%.

  Next, the obtained raw material powder, an organic solvent, an organic binder (resin), and, if necessary, a plasticizer, an antistatic agent, a dispersant, an antifoaming agent, a surfactant, a wetting agent, other additives, etc. To form a ceramic slurry, which is then molded using a doctor blade method, a nozzle coater, etc., and a sheet-like ceramic is formed on a substrate P such as a resin film such as polyethylene terephthalate (PET) as shown in FIG. The green sheet layer 2 is formed.

  Here, the organic solvent is not particularly limited, and for example, ethanol, butanol, propanol, acetone, diacetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, bromochloromethane, toluene, xylene and the like can be used. The type of the organic binder is not particularly limited, and examples thereof include polyvinyl butyral, polyvinyl alcohol, polyethylene, ethyl cellulose, acrylic, and acrylonitrile binders. Among these, polyvinyl butyral is used. More preferred. Examples of the plasticizer include phthalate and phthalate esters, derivatives thereof, and polyethylene glycol derivatives.

  Further, as shown in FIG. 3, a conductive paste mainly containing a refractory metal is screen-printed on each of the plurality of individual regions 3 for forming the multilayer ceramic capacitor 1 on the ceramic green sheet layer 2. Thus, an internal electrode green sheet layer is formed as a pattern for forming the internal electrode 12 shown in FIG. The conductive paste is a conductor powder containing particles of metal having a melting point higher than the firing temperature of the ceramic green sheet layer 2 to be described later, such as particles of Ni, Pt, Pd, alloy powders mainly composed of these metals and composite metals. Can be prepared by mixing with a co-material, an organic binder, an organic solvent, and, if necessary, a plasticizer, a dispersant, an antifoaming agent, an additive and the like. As the co-material, it is preferable to use the same type of ceramic as that contained in the ceramic green sheet layer 2 and may contain other appropriate additives. The type of the organic binder is not particularly limited, and examples thereof include ethyl cellulose, polyvinyl butyral, and acrylonitrile, and among these, ethyl cellulose is more preferable.

  Next, the ceramic green sheet layer 2 on which a pattern for forming the internal electrodes 12 for a plurality of pieces is formed and the ceramic green sheet layer 2 on which the pattern is not formed are alternately laminated by an appropriate method, A multilayer structure (multilayer body in the present invention) in which a plurality of substrate structures of the multilayer ceramic capacitor 1 shown in FIG. 1 (a structure in which the via electrode 14 and the external connection pad 16 are not formed in FIG. 1) is formed is obtained. (First step). As a lamination method at this time, for example, the ceramic green sheet layer 2 shown in FIG. 2 is further formed on the ceramic green sheet layer 2 shown in FIG. 3 by using a doctor blade method, a nozzle coater or the like. 3. A method of printing a pattern for forming internal electrodes 12 for a plurality of individual pieces shown in FIG. 3, on a ceramic green sheet layer 2 shown in FIG. 3, and a substrate such as a PET film from the ceramic green sheet layer 2 shown in FIG. For example, a method in which P is peeled off is sequentially laminated. At this time, it may laminate | stack before peeling the base material P, and may peel the one or both base materials P after that. Moreover, you may press-fit etc. by a heat | fever or pressurization etc. for every lamination | stacking.

  Next, using various press methods such as a die press, hydrostatic press (SIP), and heated isostatic press (WIP) alone or in combination, the laminated structure is further pressed (green press). .

  Then, the laminated structure after the green press is heat-treated and solidified and dried (second step). The heating conditions are not particularly limited. For example, the heating rate S1 is preferably 10 to 300 ° C./hour, more preferably 20 to 200 ° C./hour, and the holding temperature T1 is preferably 50 ° C. or more, more preferably. Is 125 ° C. or higher, more preferably 125 to 230 ° C., particularly preferably 140 to 230 ° C., and the holding time t1 of the holding temperature T1 is preferably 4 to 12 hours, more preferably 4 to 8 hours. Can be mentioned. Such heat treatment may be performed in an atmospheric pressure, a reduced pressure atmosphere, an unpressurized state, or may be performed under pressure. By such heat treatment, the organic binder and solvent contained in the green sheet layer constituting the laminated structure are removed and removed (debindered) according to the amount of heat applied and solidified and dried. And hardened.

  At this time, the laminated structure has a Vickers hardness of preferably 20 HV or more, more preferably 35 HV or more, or preferably 55 HV or less, and particularly preferably a Vickers hardness of 35 to 55 HV. It is more preferable to perform the heat treatment. Note that the above heating temperature condition substantially corresponds to these Vickers hardnesses.

  Next, a cap layer having a smaller hardness (softer) than the laminated structure is formed on the outermost layer of the solidified and dried laminated structure (sixth step). The cap layer is not particularly limited as long as it has a hardness smaller than that of the laminated structure, and is the same type as the matrix component (ceramic, conductor) of the ceramic green sheet layer or internal electrode green sheet layer constituting the laminated structure. It is preferable to use a material made of a material or a material that is hardly entangled by a micro drill, such as a bake plate. Furthermore, it is more preferable to form a layer containing a grindstone component or a layer containing a metal component as the cap layer.

  Then, in the solidified and dried laminated structure, a via hole (through hole) is drilled using a micro drill at a position where the via electrode 14 is provided (third step). The operating condition of the micro drill is only required to be able to form a via hole having a desired opening diameter in the solidified and dried laminated structure. Examples of the opening diameter include 40 to 300 μm of the opening diameter of the via hole after firing.

  Next, after removing the cap layer, the stacked structure in which the via hole is formed is cut and divided into chips. The cutting method is not particularly limited, and for example, dicing using a dicer can be used. In addition, you may implement a cap layer, after cutting a laminated structure into a chip | tip.

Then, after the laminated structure divided into chips is further debindered as necessary, for example, in a reducing atmosphere of H ₂ / N ₂ at about several hundred degrees C, in an inert gas atmosphere, or in the air, For example, baking is performed for a predetermined time in a reducing atmosphere of about 1100 ° C. to 1400 ° C. (for example, an atmosphere having an oxygen partial pressure of less than 1.0 × 10 ⁻² Pa, an H ₂ / N ₂ atmosphere). Furthermore, for example, at 900 to 1200 ° C., reoxidation treatment (annealing) for a predetermined time in an atmosphere (N ₂ atmosphere) having an oxygen partial pressure of 1.0 × 10 ⁻⁸ Pa or higher, for example, higher than the reducing atmosphere. To obtain a sintered structure in which the ceramic green sheet layer 2 is sintered with the via hole opened (seventh step).

  Next, a conductive paste for forming the via electrode 14 is filled into the via hole of each individual sintered structure (fourth step). The conductive paste includes, for example, particles of mainly at least one metal of Cu, Ag, and Au, or an alloy or composite metal mainly composed of each of these metals, and further includes Ni, Pt, and Pd. A conductor powder containing particles of at least one of these metals, or an alloy or composite metal containing these metals as a main component can be prepared by mixing with an organic binder. As the conductor powder, Cu powder (Cu Mainly containing alloy powder and composite metal powder. The same shall apply hereinafter), and Ni powder (including alloy powder and composite metal powder containing Ni as the main ingredient. Is more preferable. Moreover, it does not specifically limit as a kind of organic binder, For example, an ethylcellulose type | system | group, a polyvinyl butyral type | system | group, an acrylonitrile type | system | group, etc. are mentioned, Among these, an ethylcellulose type | system | group is more preferable. Furthermore, from the viewpoint of improving the adhesion between the dielectric layer 11 and the via electrode 14, glass frit may be added as an auxiliary agent to the conductive paste.

  Here, the shape of the Cu particles and Ni particles contained in the conductor powder is not particularly limited, and examples thereof include a spherical shape, a square shape, and a flat shape. Among these, a spherical shape is preferable. Further, their particle size and particle size distribution are not particularly limited. For example, those having an average particle size of submicron order to several tens of microns order can be used.

  Further, the case of using mixed conductor powder in which Ni powder is added to Cu powder will be described as an example. The content ratio of Ni to Cu in the mixed conductor powder is preferably greater than 0 and less than 40% by mass. It is more preferable that it is from mass% to 30 mass%. If this content ratio is greater than 0, that is, if the Ni powder is contained in the Cu powder, the via hole is sufficiently filled with the via electrode 14 in the finally formed multilayer ceramic capacitor 1, and the internal electrode 12 and the via electrode 14 can be reliably connected to each other, the occurrence of structural defects can be easily suppressed, and the moisture resistance can be easily improved. On the other hand, if the content ratio is less than 40% by mass, the conduction performance between the internal electrode 12 and the via electrode 14 can be more reliably improved, and in addition, the occurrence of structural defects can be more reliably prevented. it can. Furthermore, when the content ratio is 2% by mass or more and 30% by mass or less, it is useful in that the moisture resistance of the multilayer ceramic capacitor 1 can be further reliably improved.

  Further, the case of using a conductor powder containing Cu powder and Ni powder will be described as an example. When the average particle size of Cu particles is twice or more than the average particle size of Ni particles, the multilayer ceramic capacitor 1 has a This is preferable because it is easy to prevent the occurrence of lamination. Further, the combination of using Ni as the main component of the conductor material of the internal electrode 12 and Cu as the main component of the conductor material of the via electrode 14 has a high activity of the alloy reaction between Ni and Cu (the reaction is dense). This is preferable because the coupling is strong and conduction is easily ensured. On the other hand, for example, when Ni is used as the main component of the conductive material of the internal electrode 12 and Ni is also used as the main component of the conductive material of the via electrode 14, the Ni of the internal electrode 12 subjected to the baking treatment and the via Since the reaction with Ni in the conductive material of the electrode 14 is relatively sparse, it tends to be difficult to ensure conduction between the two.

  Further, the method of filling the conductive paste into the via hole of the sintered structure is not particularly limited as long as the method can sufficiently perform the filling, and pressure printing, hand printing, vacuum suction, Examples of the method include pushing in with a squeegee.

Next, the binder structure in which the conductive paste is filled in the via hole is removed from the binder in, for example, an H ₂ / N ₂ reducing atmosphere, an inert gas atmosphere, or the atmosphere of about several hundred degrees Celsius. Then, for example, an H ₂ / N ₂ reducing atmosphere of about 700 ° C. to 900 ° C. or N ₂ gas as a main component, and oxygen is added by at least one kind of gas of H ₂ , H ₂ O, CO ₂ and CO. A baking process is performed for a predetermined time in an atmosphere in which the partial pressure is controlled to obtain a structure in which the via electrode 14 is formed (in the state where the external connection pad 16 is not formed in the multilayer ceramic capacitor 1 shown in FIG. 1). (5th process).

  Then, patterning is performed by a method such as applying a conductive paste containing an appropriate conductor on both end portions of the via electrode 14 on the upper wall surface and the bottom wall surface of the structure, and this is performed at a predetermined temperature in an appropriate atmosphere. The external connection pad 16 is formed by firing for a predetermined time to obtain the multilayer ceramic capacitor 1 shown in FIG.

  According to the multilayer ceramic capacitor 1 and the manufacturing method thereof according to the present invention described above, the multilayer structure is solidified and dried by heat treatment before the via hole is formed in the multilayer structure of the ceramic green sheet layer and the internal electrode green sheet layer. However, since it becomes harder than before heat treatment, when drilling a via hole with a micro drill, a part of the green sheet layer of the laminated structure adheres to the outer surface of the micro drill as a drill residue. Can be suppressed. Thereby, it is possible to prevent the conduction between the via electrode 14 filled in the via hole and the internal electrode 12, and as a result, the reliability and productivity of the multilayer ceramic capacitor 1 can be improved.

  In addition, in the second step, when the laminated structure is subjected to heat treatment so that the Vickers hardness is 20 HV or more, the conduction characteristics between the via electrode 14 and the internal electrode 12 are significantly improved as compared with the case where the heat treatment is not performed. Further, by performing heat treatment so that the Vickers hardness of the laminated structure becomes 35 HV or more, the via electrode 14 and the internal electrode 12 are easily connected to each other.

  Furthermore, in the second step, if the laminated body is heat-treated so that the Vickers hardness is 55 HV or less, it is easy to suppress the micro drill from being repelled on the surface of the laminated structure, and the positional deviation of the via hole is sufficiently prevented. It is possible to prevent, that is, improve the positional accuracy of via hole formation.

  Furthermore, by performing a sixth step of forming a cap layer having a hardness lower than that of the laminated structure on the outermost layer of the solidified and dried laminated structure, via holes that may be caused by the microdrill being repelled. The positional deviation can be further easily suppressed, and the drill residue of the laminated structure can be prevented from adhering to the surface of the laminated structure.

  The cap layer is not particularly limited as long as it has a hardness lower than that of the solidified and dried laminated structure. However, the cap layer may cause dirt adhesion due to the rotational entrainment of the microdrill. It is useful to use a material made of the same type of material as the matrix component (ceramic, conductor) of the sheet layer or the internal electrode green sheet layer, or a material (for example, a bake plate) that is unlikely to be caught by a micro drill. Further, when a layer containing a grindstone component (abrasive grain content) or a layer containing a metal component is formed as the cap layer, due to their dressing effect, the drill chips accumulated in the groove of the microdrill are easily removed and easily removed.

  Further, after firing the laminated structure of the ceramic green sheet layer 2 and the internal electrode green sheet layer in which the via hole is formed, the via hole is filled with a conductive paste for forming the via electrode 14 and the baking treatment is performed. In other words, when the conductive paste for forming the via electrode 14 is baked, the dielectric layer 11 (integrated dielectric layer 10) that is a sintered body of the ceramic green sheet layer 2 is already formed. Therefore, the baking temperature of the conductive paste for forming the via electrode 14 can be made lower than the melting point of the conductor material, which is sufficiently lower than the baking temperature of the ceramic green sheet layer 2. The degree of expansion and contraction of 11 can be kept sufficiently small.

  Further, even when the conductive paste for forming the via electrode 14 is baked in this state, the difference in the degree of relative expansion and contraction between the dielectric layer 11 and the internal electrode 12 and the via electrode 14 is reduced. In addition, it is possible to effectively prevent the dielectric layer 11 and the internal electrode 12 and the via electrode 14 from being separated to form a gap therebetween. As a result, the via electrode 14 and the internal electrode 12 can be more reliably conducted. Furthermore, since a gap is prevented from being generated in the via hole and the via hole is sufficiently filled with the via electrode 14, the multilayer ceramic capacitor 1 with improved moisture resistance and little deterioration with time can be obtained.

  Furthermore, since the dielectric layer 11 and the internal electrode 12 are formed by baking before baking the conductive paste for forming the via electrode 14, baking is performed at a temperature sufficiently lower than the baking temperature of the ceramic green sheet layer 2. Therefore, the relative expansion / contraction behavior between the conductive paste for forming the internal electrode 12 and the via electrode 14 and the ceramic green sheet layer 2 can be reduced. This makes it possible to sufficiently suppress structural defects such as cracks in the dielectric layer 11 and delamination.

  Further, when a mixed conductor powder containing a metal powder such as Ni having a higher melting point is used in addition to a metal powder such as Cu as the conductive paste for forming the via electrode 14, particles such as Ni having a high melting point are formed. Bonding with them in the state of being interposed between particles of low melting point Cu, etc., and exerting a pinning action on the particles of Cu, etc., so that the progress of the metal reaction between the particles of Cu, etc. is moderately suppressed Can do. As a result, it is possible to effectively prevent the space filling rate due to Cu or the like in the via hole from being excessively decreased due to excessive reaction between metals such as Cu and a decrease in occupied volume. Therefore, the conduction between the internal electrode 12 and the via electrode 14 can be realized more reliably.

  In addition, as above-mentioned, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can add suitably. For example, in addition to the examples illustrated in the above embodiments, the method for manufacturing a multilayer ceramic electronic component in the present invention is not limited to the manufacture of a multilayer ceramic capacitor, but also for manufacturing other multilayer ceramic electronic components such as a multilayer ceramic inductor. Applicable.

  Moreover, although the 7th process which performs a baking process once to the laminated structure in which the via hole was formed was implemented between the 3rd process and the 4th process, you may abbreviate | omit this 7th process. In this case, in the fifth step, the green laminated structure in which the via hole is filled with the conductive paste for forming the via electrode 14 is fired, that is, the ceramic green sheet layer, the internal electrode green sheet layer, and the conductive layer. The multilayer ceramic capacitor 1 can be obtained by simultaneously firing the conductive paste. In this case, the conductive paste for forming the via electrode 14 is preferably the same type as the conductive paste for forming the internal electrode 12. For example, a paste containing at least one of Ni, Pt, and Pd is used. May be. Furthermore, the sixth step of forming the cap layer may be omitted.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example)
First, a multilayer ceramic capacitor having the same structure as shown in FIG. 1 was manufactured in the same manner as the above-described manufacturing procedure (the procedure in which the sixth step and the seventh step were omitted). The specific main process conditions at this time were as follows.

That is, first, the thickness of the dried ceramic green sheet was about 5 μm. The thickness of the pattern of the conductive paste for forming the internal electrode formed on the ceramic green sheet layer was about 1.2 μm. Furthermore, the heat treatment of the green-pressed laminated structure was performed in the atmosphere, the holding temperature T1 at that time was set to a range of 50 to 300 ° C., and the holding time t1 was set to 5 hours. In addition, the via hole formed in the solidified and dried laminated structure was drilled using a micro drill (drill diameter 150 μm, rotation speed 100,000 rpm). Furthermore, the via fill used a method of filling the via hole with Ni paste by repeating vacuum suction printing a plurality of times. Furthermore, the division into pieces was performed using a dicer having a cutting blade having a thickness of 0.35 mm. Further, the binder removal of the laminated structure in which the via holes are formed is performed in a H ₂ / N ₂ reducing atmosphere at 400 ° C., and the subsequent firing is performed in a strong H ₂ / N ₂ reducing atmosphere at 1150 ° C. to 1300 ° C. Went for hours.

(Comparative example)
A multilayer ceramic capacitor was obtained under the same conditions as in the above-described example except that the green pressed multilayer structure was not solidified and dried by heat treatment.

(Evaluation 1)
For the various multilayer ceramic capacitors obtained, (1) Vickers hardness, (2) Cross-sectional blurring rate, (3) Surface blurring rate, (4) Surface dropout rate, (5) Conductivity, and (6) The position accuracy was evaluated.

  First, (1) Vickers hardness was calculated by the same method as described above.

  In addition, (2) the evaluation of the occurrence rate of the blurring in the cross section is such that the via hole is divided into two along the axial direction in the laminated structure in which the via fill is not performed (the via hole is not filled with the conductive paste). The cross section is magnified and observed at a magnification of 100 times using a solid metal microscope, and the number of the dielectric film adhering to the inner wall of the via hole (the occurrence of the fading of the cross section) is counted. Then, the ratio (percentage%) of the number of individuals in which cross-section blurring occurred relative to the number of sample bases subjected to observation was calculated and used as an index.

  Furthermore, (3) the evaluation of the incidence of surface debris is based on the fact that the periphery of the via hole on the opening surface of the laminated structure in which the via hole is formed (the distance from the via hole circle center is approximately twice the diameter of the via hole) Using a microscope, magnified observation at a magnification of 100 times, counting the number of drill debris adhering to the surface (occurrence of surface debris), the ratio of the number of individuals with surface debris to the number of sample bases used for observation ( %) Was calculated and used as an index.

  Still further, (4) the rate of occurrence of surface drop-off is evaluated by magnifying and observing the via hole opening of the laminated structure in which the via hole is formed at a magnification of 100 times using a solid metal microscope, and the via hole opening end has a diameter of the via hole. Count the number of the dropouts (occurrence of surface dropout) with a size of 1/5 or more, and calculate the ratio (percentage%) of the number of individuals with surface dropouts to the number of sample bases used for observation. Was used as an index.

  Furthermore, (5) the conductivity was evaluated using the ratio (percentage%) of the measured value of the capacitance to the expected capacitance (design specification value) of the multilayer ceramic capacitor as an index. Although the presence / absence of conduction can be confirmed by current-resistance measurement, the capacitance measurement has a higher reading sensitivity than the resistance measurement, and therefore can be evaluated more accurately. Adopted.

  Further, (6) the evaluation of the positional accuracy is based on the difference between the position coordinates where the via holes are actually formed with respect to the intended position coordinates (design specification values) of the via holes formed in the multilayer ceramic capacitor. The difference (μm) between the design specification value of the distance and the actually measured value was used as an index. Therefore, the smaller the position accuracy value, the smaller the positional deviation.

  Table 1 summarizes various evaluation results for the multilayer ceramic capacitors of Examples and Comparative Examples.

  The present invention can prevent the conduction between the via electrode and the internal electrode filled in the via hole, thereby improving the reliability and productivity of the multilayer ceramic electronic component product, The present invention can be widely and effectively used for multilayer ceramic electronic components such as multilayer ceramic capacitors and multilayer ceramic inductors, devices, apparatuses, systems, facilities, and the like including them.

It is sectional drawing which shows schematic structure of an example of the multilayer ceramic electronic component obtained using the manufacturing method of the multilayer ceramic electronic component by this invention. FIG. 3 is a process diagram showing a part of an example of a procedure for manufacturing the multilayer ceramic capacitor 1. FIG. 3 is a process diagram showing a part of an example of a procedure for manufacturing the multilayer ceramic capacitor 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor (multilayer ceramic electronic component), 2 ... Ceramic green sheet layer, 3 ... Piece area, 10, 11 ... Dielectric layer, 12 ... Internal electrode, 14 ... Via electrode, 16 ... External connection pad, P: Base material.

Claims (7)

A first step of forming a laminate by laminating at least one ceramic green sheet layer containing a dielectric material for forming a dielectric layer and at least one internal electrode green sheet layer containing a conductor material for forming an internal electrode; ,
A second step of subjecting the laminate to a heat treatment at a holding temperature of 50 to 300 ° C., and forming a laminate in a solidified and dried state than the laminate before the heat treatment;
A third step of forming a via hole penetrating the solidified and dried laminate using a micro drill; and
A fourth step of filling the via hole with a conductor material for forming a via electrode;
A fifth step of firing the laminate in which the via hole is filled with the conductive material for electrode formation;
A method for manufacturing a multilayer ceramic electronic component comprising: In the second step, a laminate having a Vickers hardness of 20 HV or more is formed.
The method for producing a multilayer ceramic electronic component according to claim 1. In the second step, a laminate having a Vickers hardness of 35 HV or more is formed.
The method for producing a multilayer ceramic electronic component according to claim 1. In the second step, a laminate having a Vickers hardness of 55 HV or less is formed.
The method for producing a multilayer ceramic electronic component according to claim 1. Including the sixth step of forming a cap layer having a hardness lower than that of the laminate on the outermost layer of the solidified and dried laminate, which is performed before the third step is performed;
In the third step, a via hole penetrating the laminated body in which the cap layer is formed and solidified and dried is formed using a micro drill.
The method for producing a multilayer ceramic electronic component according to claim 1. In the sixth step, a layer containing a grindstone component or a layer containing a metal component is formed as the cap layer.
The method for producing a multilayer ceramic electronic component according to claim 5. A seventh step is performed between the third step and the fourth step, and a seventh step of obtaining a laminate in which the dielectric layer and the internal electrode are formed by performing a baking process on the laminate in which the via hole is formed. Including
In the fourth step, the via hole in the laminated body in which the dielectric layer and the internal electrode are formed is filled with the conductive material for forming the via electrode,
In the fifth step, a via electrode is formed by firing the laminate in which the conductor material is filled in the via hole.
The method for producing a multilayer ceramic electronic component according to claim 1.

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