JP7067296B2 - Screening method for laminated ceramic electronic components - Google Patents

Description

The present invention relates to a method for screening laminated ceramic electronic components.

In recent years, in laminated ceramic electronic components such as multilayer ceramic capacitors, there is a demand for miniaturization and an increase in capacitance, and the demand for laminated ceramic electronic components is increasing year by year. Under such circumstances, in the process of manufacturing the laminated ceramic electronic component, there are structural defects such as voids that are potentially present inside the base electrode layer in the external electrode and inside the laminated body of the laminated ceramic electronic component. In some cases.

As described above, when a plating layer is formed on the base electrode layer for a material having structural defects such as voids inside the base electrode layer of the external electrode or inside the laminated body of the laminated ceramic electronic component, the base electrode is used. The plating solution enters the inside of the laminate from the structural defect portion such as the void of the layer, and the plating solution remains in the gap between the internal electrode and the dielectric layer and the structural defect portion such as the void of the dielectric layer inside the laminate. Later, it was found that peeling occurred between the dielectric layers and between the dielectric layers and the internal electrodes. As a result, it was found that short circuits, IR deterioration (deterioration of insulation resistance), and deterioration of moisture resistance may occur in the laminated ceramic electronic components.

Therefore, as a method for removing the laminated ceramic electronic component in which a structural defect has occurred, for example, a method as in Patent Document 1 is known.

Japanese Unexamined Patent Publication No. 9-21934

However, although the method of Patent Document 1 is effective for a laminated ceramic capacitor (multilayer ceramic electronic component) having obvious structural defects such as cracks, the inside of the base electrode layer of the external electrode or the inside of the base electrode layer of the external electrode can be used. The effect cannot be obtained for those having structural defects such as potential voids inside the laminated body of the laminated ceramic capacitor (laminated ceramic electronic component). Specifically, structural defects such as peeling that may occur after plating cannot be removed between the dielectric layers or between the dielectric layers and the internal electrodes.

Therefore, the present invention provides a screening method for multilayer ceramic electronic components such as multilayer ceramic capacitors that can solve the above problems.

The method for screening a laminated ceramic electronic component according to the present invention is arranged on a laminated body having a plurality of laminated dielectric layers, a plurality of internal electrodes arranged on the dielectric layer, and a surface of the laminated body. A method for screening a laminated ceramic electronic component having an external electrode, in which the laminated ceramic electronic component is put into a barrel, and the entire barrel containing the laminated ceramic electronic component is immersed in an electrolytic solution, and vacuum is applied or pressure is applied. The process, the process of further injecting a conductive shot into the barrel and rotating the barrel with the laminated ceramic electronic components immersed in the electrolytic solution, and the process of applying a positive potential to the electrode rod (anode) provided in the electrolytic solution. After the steps of It is characterized by providing a step of performing the above.

In the present invention, a plating layer is formed on the base electrode layer in a laminated ceramic electronic component having a potential structural defect such as a void inside the base electrode layer of the external electrode or inside the laminate of the laminated ceramic electronic component. However, the plating solution enters the inside of the laminate from the structural defect portion such as the void of the base electrode layer, and the structural defect such as the gap between the internal electrode and the dielectric layer and the potential void of the dielectric layer inside the laminate. When the plating solution remains in the portion, it is possible to remove in advance the laminated ceramic electronic parts that may cause peeling after plating between the dielectric layers or between the dielectric layer and the internal electrode. It becomes.

The mechanism is that the electrolytic solution permeates the structural defect portion (internal electrode exposed portion) by pressurization or evacuation, and a negative potential is applied to the structural defect portion (internal electrode exposed portion) to bond the dielectric layer and the internal electrode interface. The nickel oxide that is being made is reduced. Delamination occurs when this reduction proceeds beyond a certain level. The laminated ceramic electronic component in which delamination has occurred can be easily removed because it can be distinguished from a non-defective product by simple measurement, and the above-mentioned effect can be obtained.

Further, since the role of the electrolytic solution of Patent Document 1 is only to permeate and conduct the cracks straddling between the laminated bodies, only the cracks that have already occurred between the laminated bodies and are conducting to the outside can be removed. .. However, in the present invention, by using the electrolytic barrel device immersed in the electrolytic solution, it is possible to continuously apply a negative potential to the structurally defective portion of the laminated ceramic electronic component. As a result, delamination occurs only in the defective product, so that all the laminated ceramic electronic components in which the internal electrodes are exposed to the outside can be delaminated and removed.

According to the present invention, screening of laminated ceramic electronic components capable of removing laminated ceramic electronic components having structural defects such as potential voids inside the base electrode layer of the external electrode or inside the laminated body. A method can be provided.

The above-mentioned object, other object, feature and advantage of the present invention will be further clarified from the description of the embodiment for carrying out the following invention with reference to the drawings.

It is an external perspective view which shows one Embodiment of a monolithic ceramic capacitor. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1 showing a monolithic ceramic capacitor. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1 showing a monolithic ceramic capacitor. (A) is a diagram showing a structure in which a counter electrode portion of an internal electrode of a laminated body in a laminated ceramic capacitor is divided into two. (B) is a diagram showing a structure in which a counter electrode portion of an internal electrode of a laminated body in a laminated ceramic capacitor is divided into three parts. (C) is a diagram showing a structure in which a counter electrode portion of an internal electrode of a laminated body in a laminated ceramic capacitor is divided into four parts. It is a schematic diagram of the apparatus used for the screening of the multilayer ceramic capacitor which concerns on this invention. It is a flowchart which shows the screening method of the laminated ceramic capacitor which concerns on this invention.

1. 1. Laminated Ceramic Electronic Components As an example of laminated ceramic electronic components to which the present invention can be applied, a laminated ceramic capacitor will be described in this embodiment, but it goes without saying that a laminated ceramic electronic component such as a varistor may be used. stomach.

The laminated ceramic capacitor 10 will be described as an example of a laminated ceramic electronic component to which the present invention can be applied. FIG. 1 is an external perspective view showing an embodiment of a monolithic ceramic capacitor. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1 showing a monolithic ceramic capacitor. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1 showing a monolithic ceramic capacitor. FIG. 4A is a diagram showing a structure in which the counter electrode portion of the internal electrode of the laminated body of the laminated ceramic capacitor is divided into two. FIG. 4B is a diagram showing a structure in which the counter electrode portion of the internal electrode of the laminated body of the laminated ceramic capacitor is divided into three parts. FIG. 4C is a diagram showing a structure in which the counter electrode portion of the internal electrode of the laminated body of the laminated ceramic capacitor is divided into four parts.

As shown in FIGS. 1 to 3, the laminated ceramic capacitor 10 includes a laminated body 12 having a rectangular parallelepiped shape.

(Laminated body 12)
The laminated body 12 includes a plurality of laminated dielectric layers 14 and a plurality of internal electrodes 16, and is orthogonal to the first main surface 12a and the second main surface 12b facing the stacking direction x and the stacking direction x. The first side surface 12c and the second side surface 12d facing the width direction y, and the first end surface 12e and the second end surface 12f facing the length direction z orthogonal to the stacking direction x and the width direction y. including. Further, it is preferable that the laminated body 12 has rounded corners and ridges. The corner portion is a portion where three adjacent surfaces of the laminated body 12 intersect, and the ridge portion is a portion where two adjacent surfaces of the laminated body 12 intersect. Further, unevenness or the like is formed on a part or the whole of the first main surface 12a and the second main surface 12b, the first side surface 12c and the second side surface 12d, and the first end surface 12e and the second end surface 12f. It may have been.

The dimensions of the laminate 12 are such that the dimension L in the length direction z connecting the first end surface 12e and the second end surface 12f is 0.15 mm or more and 6.8 mm or less, and the first side surface 12c and the second side surface 12d. When the dimension W in the width direction y connecting the above is 0.07 mm or more and 5.8 mm or less, and the dimension T in the stacking direction x connecting the first main surface 12a and the second main surface 12b is 0.07 mm or more and 2.9 mm or less. It is preferable to have.

(Dielectric layer 14)
The dielectric layer 14 includes an outer layer portion 14a composed of a plurality of dielectric layers 14 and an inner layer portion 14b composed of a plurality of dielectric layers 14 and a plurality of internal electrodes 16. The outer layer portion 14a is located on the side of the first main surface 12a and the second main surface 12b of the laminated body 12, and is the first main surface 12a and the second main surface 12b, and the first main surface 12a and the first main surface 12a. It is a dielectric layer 14 located between the internal electrode 16 near the main surface 12b of 2. Further, the region sandwiched between the two outer layer portions 14a is the inner layer portion 14b.

As the ceramic material of the dielectric layer 14 of the laminated body 12, for example, a dielectric ceramic composed of a main component such as BaTiO ₃ , CaTIO ₃ , SrZrO ₃ , and CaZrO ₃ can be used. Further, those in which sub-components such as Mn compound, Fe compound, Cr compound, Co compound and Ni compound are added to these main components may be used.

In addition, piezoelectric ceramics such as PZT-based ceramics, semiconductor ceramics such as spinel-based ceramics, and magnetic ceramics such as ferrite can also be used. Further, when a piezoelectric ceramic is used, it functions as a piezoelectric component, when a semiconductor ceramic is used, it functions as a thermistor, and when a magnetic ceramic is used, it functions as an inductor. However, in the case of an inductor, the internal electrode is a coiled conductor.

The thickness of each of the dielectric layers 14 is preferably 0.7 μm or more and 30 μm or less. The number of the dielectric layers 14 is preferably 10 or more and 1000 or less including the outer layer portion 14a. The thickness of the outer layer portion 14a is preferably 50 μm or more and 400 μm or less.

(Internal electrode 16)
The internal electrodes 16 are alternately laminated with the plurality of dielectric layers 14, the first internal electrodes 16a exposed to the first end surface 12e, and the plurality of dielectric layers 14 are alternately laminated with the second end surface 12f. It has a second internal electrode 16b exposed to the surface.

The first internal electrode 16a is a first opposed electrode portion 18a facing the second internal electrode 16b and a first facing electrode portion 18a drawn from the first counter electrode portion 18a to the first end surface 12e of the laminated body 12. It is provided with a drawer electrode portion 20a. The end of the first extraction electrode portion 20a of the first internal electrode 16a is drawn out to the surface of the first end surface 12e of the laminated body 12, and forms an exposed portion.

The second internal electrode 16b is a second opposed electrode portion 18b that faces the first internal electrode 16a and is drawn from the second counter electrode portion 18b to the second end surface 12f of the laminated body 12. It is provided with a drawer electrode portion 20b. The end of the second drawer electrode portion 20b of the second internal electrode 16b is drawn out to the surface of the second end surface 12f of the laminated body 12, and forms an exposed portion.

The counter electrode portion 18 is composed of a counter electrode portion 18a of the first internal electrode 16a and a counter electrode portion 18b of the second internal electrode 16b. The shapes of the first counter electrode portion 18a and the second counter electrode portion 18b are not particularly limited, but are preferably rectangular. However, the corners of the first counter electrode portion 18a and the second counter electrode portion 18b may be rounded or the corner portions may be formed diagonally (tapered).

The extraction electrode portion 20 is composed of the extraction electrode portion 20a of the first internal electrode 16a and the extraction electrode portion 20b of the second internal electrode 16b. The shapes of the first drawer electrode portion 20a and the second drawer electrode portion 20b are not particularly limited, but are preferably rectangular. However, the corners of the first drawer electrode portion 20a and the second drawer electrode portion 20b may be rounded or the corner portions may be formed diagonally (tapered).

The width of the first counter electrode portion 18a of the first internal electrode 16a and the second counter electrode portion 18b of the second internal electrode 16b, and the width of the first extraction electrode portion 20a and the second lead electrode portion 20a of the first internal electrode 16a. The width of the second extraction electrode portion 20b of the internal electrode 16b may be formed to be the same width, or one of them may be formed to have a narrow width.

Further, in the laminated body 12, the first internal electrode 16a and the second internal electrode 16b, and the first opposed electrode portion 18a and the second opposed electrode portion 18a and the second opposed electrode portion 18a and the second opposed electrode portion 18a and the second internal electrode 16b and the first internal electrode 16a and the second internal electrode 16b face each other. With the electrode portion 18b and the side portion 22a (W gap) of the laminate 12 located between the first counter electrode portion 18a and the second counter electrode portion 18b and the first side surface 12c and the second side surface 12d. , Which of the first internal electrode 16a and the second internal electrode 16b is located between the first counter electrode portion 18a and the second counter electrode portion 18b and the first end surface 12e and the second end surface 12f. It includes an end portion 22b (L gap) of the laminate 12 including one of the first extraction electrode portions 20a and the second extraction electrode portion 20b.

Further, as shown in FIG. 4, the internal electrode 16 is provided with a floating internal electrode 16c that is not drawn out to either the first end surface 12e or the second end surface 12f, and is opposed by the floating internal electrode 16c. The electrode portion 18 may be divided into a plurality of structures. For example, it is a double structure (see FIG. 4A), a triple structure (see FIG. 4B), and a quadruple structure (see FIG. 4C). Needless to say, a structure of four or more stations may be used. By forming the counter electrode portion 18 into a plurality of parts in this way, a plurality of capacitor components are formed between the facing internal electrodes 16, and these capacitor components are connected in series. Therefore, the voltage applied to each capacitor component becomes low, and the withstand voltage of the monolithic ceramic capacitor 10 can be increased.

The first internal electrode 16a and the second internal electrode 16b may be appropriately used, for example, a metal such as Ni, Cu, Ag, Pd, Au, or an alloy containing at least one of these metals such as an Ag—Pd alloy. It can be made of a conductive material of.

In the present embodiment, the first counter electrode portion 18a of the first internal electrode 16a and the second counter electrode portion 18b of the second internal electrode 16b face each other via the dielectric layer 14 to form a capacitance. Is formed, and the characteristics of the capacitor are exhibited.

The thickness of each of the first internal electrode 16a and the second internal electrode 16b is preferably, for example, 0.2 μm or more and 2.0 μm or less. The number of internal electrodes 16 is preferably 5 or more and 500 or less.

(External electrode 24)
The external electrode 24 has a first external electrode 24a and a second external electrode 24b.

The first external electrode 24a and the second external electrode 24b are located on the first end surface 12e and the second end surface 12f. The first external electrode 24a and the second external electrode 24b are a part on the first main surface 12a, a part on the second main surface 12b, a part on the first side surface 12c, and the first. It is preferable that the surface 2 is arranged so as to extend to a part on the side surface 12d. It is preferable that it is formed so as to extend to at least a part on 12b on the second main surface located on the mounting surface side.

The first external electrode 24a is connected to the first internal electrode 16a. The second external electrode 24b is connected to the second internal electrode 16b.

The first external electrode 24a and the second external electrode 24b preferably have a base electrode layer 26 and a plating layer 28, but do not necessarily have to have the plating layer 28.

The base electrode layer 26 has a first base electrode layer 26a and a second base electrode layer 26b. The base electrode layer 26 includes at least one selected from a baking layer, a conductive resin layer, a thin film layer, and the like.

The baking layer contains a glass component and a metal. The glass component of the baking layer contains at least one selected from B, Si, Ba, Mg, Al, Li and the like. The metal of the baking layer contains at least one selected from, for example, Cu, Ni, Ag, Pd, Ag—Pd alloy, Au and the like. The baking layer may be a plurality of layers.

The baking layer is formed by applying a conductive paste containing glass and metal to the laminate 12 and baking it, and may be simultaneously fired with the internal electrode 16 or may be baked after the internal electrode 16 is fired.

The thickness of the first baking layer and the second baking layer at the central portion in the height direction of the first base electrode layer 26a and the second base electrode layer 26b located on the first end face 12e and the second end face 12f is For example, it is preferably 10 μm or more and 200 μm or less. Further, when the base electrode layer 26 is provided on the first main surface 12a and the second main surface 12b, the first side surface 12c and the second side surface 12d, the first main surface 12a and the second main surface 12a and the second main surface 12a are provided. The first baking layer and the second in the central portion in the length direction of the first base electrode layer 26a and the second base electrode layer 26b located on the surface 12b, the first side surface 12c and the second side surface 12d. The thickness of the baked layer is preferably 5 μm or more and 50 μm or less, for example.

The conductive resin layer contains a thermosetting resin and a metal. When forming the conductive resin layer, it may be formed directly on the laminated body 12 without forming the baking layer.

As the thermosetting resin of the conductive resin layer, for example, various known thermosetting resins such as epoxy resin, phenol resin, urethane resin, silicone resin, and polyimide resin can be used. Among them, epoxy resin having excellent heat resistance, moisture resistance, adhesion and the like is one of the most suitable resins.

The thermosetting resin contained in the conductive resin layer is preferably contained in an amount of 25 vol% or more and 65 vol% or less with respect to the total volume of the conductive resin.

Further, it is preferable that the conductive resin layer contains a curing agent together with the thermosetting resin. When an epoxy resin is used as the base resin, various known compounds such as phenol-based, amine-based, acid anhydride-based, and imidazole-based compounds can be used as the curing agent for the epoxy resin.

The metal contained in the conductive resin layer mainly bears the electrical conductivity of the conductive resin layer. Specifically, when the metals contained in the conductive resin layer come into contact with each other, an energization path is formed inside the conductive resin layer.

The shape of the metal contained in the conductive resin layer is not particularly limited. As the metal contained in the conductive resin layer, a spherical metal, a flat metal, or the like can be used, but it is preferable to use a mixture of the spherical metal powder and the flat metal powder. Further, the average particle size of the metal contained in the conductive resin layer is not particularly limited. The average particle size of the metal contained in the conductive resin layer may be, for example, 0.3 μm or more and 10 μm or less.

As the metal contained in the conductive resin layer, Ag, Cu, or an alloy thereof can be used. Further, a metal powder having an Ag coating on the surface can be used. When an Ag-coated metal powder is used, it is preferable to use Cu or Ni as the metal powder. Further, it is also possible to use Cu obtained by subjecting it to an antioxidant treatment.

The reason for using Ag conductive metal powder as the metal of the conductive resin layer is that Ag is suitable as an electrode material because it has the lowest resistivity among metals, and Ag is a noble metal, so it does not oxidize and has weather resistance. Because it is expensive. The reason for using the Ag-coated metal is that the metal of the base material can be made inexpensive while maintaining the above-mentioned characteristics of Ag.

The metal contained in the conductive resin layer is preferably contained in an amount of 35 vol% or more and 75 vol% or less with respect to the total volume of the conductive resin.

The conductive resin layer may be a plurality of layers. The conductive resin layer may be arranged on the baking layer so as to cover the baking layer, or may be arranged directly on the laminated body 12.

The first conductive resin layer and the second conductive resin in the central portion in the height direction of the first base electrode layer 26a and the second base electrode layer 26b located on the first end face 12e and the second end face 12f. The thickness of the layer is preferably, for example, 10 μm or more and 200 μm or less. Further, when the base electrode layer 26 is provided on the first main surface 12a and the second main surface 12b, the first side surface 12c and the second side surface 12d, the first main surface 12a and the second main surface 12a and the second main surface 12a are provided. The first conductive resin layer in the central portion in the length direction z, which is the first base electrode layer 26a and the second base electrode layer 26b located on the surface 12b, the first side surface 12c and the second side surface 12d. The thickness of the second conductive resin layer is preferably 5 μm or more and 50 μm or less, for example.

Since the conductive resin layer contains a thermosetting resin, it is more flexible than the base electrode layer 26 made of, for example, a plating film or a fired product of a conductive paste. Therefore, even when a physical impact or an impact due to a thermal cycle is applied to the monolithic ceramic capacitor 10, the conductive resin layer functions as a buffer layer to prevent cracks in the monolithic ceramic capacitor 10. Can be done.

The thin film layer is a layer having a thickness of 1 μm or less, which is formed by a thin film forming method such as a sputtering method or a thin film deposition method and in which metal particles are deposited.

(Plating layer 28)
The plating layer 28 has a first plating layer 28a and a second plating layer 28b. The first plating layer 28a is arranged so as to cover the first base electrode layer 26a. The second plating layer 28b is arranged so as to cover the second base electrode layer 26b.

The plating layer 28 includes, for example, at least one selected from Cu, Ni, Ag, Pd, Ag—Pd alloy, Au and the like.

The plating layer 28 may be formed of a plurality of layers. A two-layer structure consisting of a Ni plating layer and a Sn plating layer is preferable. The Ni plating layer can prevent the base electrode layer 26 from being eroded by the solder when mounting the laminated ceramic capacitor 10, and the Sn plating layer has the wettability of the solder when mounting the laminated ceramic capacitor 10. Can be improved and easily implemented.

The thickness of the plating layer 28 per layer is preferably 2 μm or more and 15 μm or less.

The external electrode 24 may be formed only by the plating layer 28 without providing the base electrode layer 26.
Hereinafter, a structure in which the plating layer 28 is provided without providing the base electrode layer 26 will be described.

Each of the first external electrode 24a and the second external electrode 24b may not be provided with the base electrode layer 26, and the plating layer 28 may be directly formed on the surface of the laminated body 12. That is, the monolithic ceramic capacitor 10 may have a structure including a plating layer 28 electrically connected to the first internal electrode 16a or the second internal electrode 16b. In such a case, the plating layer 28 may be formed after the catalyst is disposed on the surface of the laminated body 12 as a pretreatment.

The plating layer 28 preferably includes a lower plating layer formed on the surface of the laminated body 12 and an upper plating layer formed on the surface of the lower plating layer.

It is preferable that the lower plating layer and the upper plating layer each contain at least one metal selected from, for example, Cu, Ni, Sn, Pb, Au, Ag, Pd, Bi or Zn, or an alloy containing the metal.

The lower plating layer is preferably formed using Ni having solder barrier performance, and the upper plating layer is preferably formed using Sn or Au having good solder wettability.

Further, for example, when the first internal electrode 16a and the second internal electrode 16b are formed using Ni, the lower plating layer is preferably formed using Cu having good bondability with Ni. The upper plating layer may be formed as needed, and the first external electrode 24a and the second external electrode 24b may each be composed of only the lower plating layer.

In the plating layer 28, the upper plating layer may be used as the outermost layer, or another plating layer may be formed on the surface of the upper plating layer.

In a structure in which the plating layer 28 is provided without providing the base electrode layer 26, the thickness of the plating layer 28 per layer is preferably 1 μm or more and 15 μm or less.

The plating layer 28 preferably does not contain glass. The metal ratio per unit volume of the plating layer 28 is preferably 99 vol% or more.

The dimension in the length direction z of the multilayer ceramic capacitor 10 including the laminate 12 and the external electrode 24 is defined as the _LM dimension. The _LM size is preferably 0.2 mm or more and 7.0 mm or less. The dimension in the width direction y of the multilayer ceramic capacitor 10 including the laminate 12 and the external electrode 24 is defined as the _WM dimension. The _WM size is preferably 0.1 mm or more and 6.0 mm or less. The dimension of the laminated ceramic capacitor 10 including the laminated body 12 and the external electrode 24 in the laminating direction x is defined as the _TM dimension. The _TM dimension is preferably 0.1 mm or more and 3.0 mm or less.

2. 2. Method for Manufacturing Multilayer Ceramic Electronic Components Next, a method for manufacturing a monolithic ceramic capacitor 10 will be described as an example of a method for manufacturing a monolithic ceramic electronic component to which the present invention can be applied.

First, a dielectric sheet and a conductive paste for internal electrodes are prepared. The dielectric sheet and the conductive paste for the internal electrode include a binder and a solvent, but known organic binders and organic solvents can be used.

Next, the conductive paste for the internal electrode is printed on the dielectric sheet in a predetermined pattern by, for example, screen printing or gravure printing, to form the internal electrode pattern.

Next, a predetermined number of dielectric sheets for the outer layer on which the internal electrode pattern is not printed are laminated, and the dielectric sheets for the inner layer on which the internal electrode pattern is printed are sequentially laminated on the predetermined number of the dielectric sheets, and further, the outer layer is further laminated on the dielectric sheets for the inner layer. A predetermined number of dielectric sheets for use are laminated to prepare a laminated sheet.

Next, the laminated sheet is pressed in the laminated direction by means such as a hydrostatic press to prepare a laminated block.

Next, the laminated block is cut to a predetermined size, and the laminated chips are cut out. At this time, the corners and ridges of the laminated chips may be rounded by barrel polishing or the like.

Next, the laminated chips are fired to prepare a laminated body. The firing temperature is preferably 900 ° C. or higher and 1300 ° C. or lower, although it depends on the material of the dielectric and the internal electrode.

Next, the conductive paste to be the base electrode layer 26 is applied to the first end face 12e and the second end face 12f of the laminated body 12 to form the base electrode layer 26. The base electrode layer 26 can be formed of a baking layer, a resin electrode layer, a thin film layer, or the like.

When forming the baking layer, a conductive paste containing a glass component and a metal is applied by a method such as dipping, and then the baking treatment is performed to form the base electrode layer 26. The temperature of the baking process at this time is preferably 700 ° C. or higher and 900 ° C. or lower.

When the base electrode layer 26 is formed of the conductive resin layer, the conductive resin layer can be formed by the following method. The conductive resin layer may be formed on the surface of the baking layer, or the conductive resin layer may be formed directly on the laminated body 12 by itself without forming the baking layer.
As a method for forming the conductive resin layer, a conductive resin paste containing a thermosetting resin and a metal is applied on a baking layer or a laminate 12, and heat-treated at a temperature of 250 ° C. or higher and 550 ° C. or lower to be thermally cured. The sex resin is thermoset to form a conductive resin layer. The atmosphere at the time of heat treatment at this time is preferably an N ₂ atmosphere. Further, in order to prevent the thermosetting resin from scattering and to prevent the metal from being oxidized, the oxygen concentration is preferably suppressed to 100 ppm or less.

When the base electrode layer 26 is formed of a thin film layer, the base electrode layer 26 can be formed by a thin film forming method such as a sputtering method or a thin film deposition method. The base electrode layer 26 formed of the thin film layer is a layer of 1 μm or less in which metal particles are deposited.

Further, the plating layer 28 may be provided on the exposed portion of the internal electrode 16 of the laminated body 12 without providing the base electrode layer 26. In that case, it can be formed by the following method.
The first end surface 12e and the second end surface 12f of the laminate 12 are subjected to a plating treatment to form a plating layer 28 on the exposed portion of the internal electrode 16. Either electrolytic plating or electroless plating may be used for the plating process, but electroless plating requires pretreatment with a catalyst or the like in order to improve the plating precipitation rate, which complicates the process. There is a demerit. Therefore, it is usually preferable to use electrolytic plating. As the plating method, it is preferable to use barrel plating. Further, if necessary, the upper plating layer formed on the surface of the lower plating layer may be formed in the same manner.

After that, the plating layer 28 is formed on the surface of the base electrode layer 26, the surface of the conductive resin layer, the surface of the lower plating layer, or the surface of the upper plating layer. The Ni plating layer and the Sn plating layer are sequentially formed by, for example, a barrel plating method.

As described above, the monolithic ceramic capacitor 10 which is an embodiment of the monolithic ceramic electronic component according to the present invention is manufactured.

3. 3. Method for screening laminated ceramic electronic components The method for screening laminated ceramic electronic components of the present invention is a laminated body 12 having a plurality of laminated dielectric layers 14 and a plurality of internal electrodes 16 arranged on the dielectric layers 14. It can be applied to a laminated ceramic electronic component having an external electrode 24 arranged on the surface of the laminated body 12.

As an example of a method for screening laminated ceramic electronic components to which the present invention can be applied, a method for screening a laminated ceramic capacitor 10 will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic diagram of an apparatus used for screening a monolithic ceramic capacitor according to the present invention. FIG. 6 is a flowchart showing a screening method for a multilayer ceramic capacitor according to the present invention.

First, the monolithic ceramic capacitor 10 is put into the barrel 54, the barrel 54 containing the monolithic ceramic capacitor 10 is immersed in the electrolytic solution 52, and a step (S01) of evacuating or applying pressure is performed. As shown in FIG. 5, a plurality of multilayer ceramic capacitors 10 are put into the barrel 54, and the barrel 54 containing the plurality of multilayer ceramic capacitors 10 is immersed in the electrolytic solution 52.

As shown in FIG. 5, the barrel 54 is a polygonal cylindrical bottomed barrel having a hexagonal cross-sectional shape in the direction orthogonal to the central axis C. The barrel 54 is configured to be able to rotate in the direction of the arrow (R direction) in FIG. 5 with the central axis C as the rotation axis.

The electrolytic solution 52 used in the present invention is a neutral aqueous solution or an alkaline aqueous solution, and among them, a neutral metal salt aqueous solution such as sodium sulfate or an alkaline metal salt aqueous solution such as sodium carbonate or sodium borate is used. Is preferable. As a result, the delamination phenomenon due to the reduction of nickel oxide is promoted, so that the effect of the present invention can be further ensured.

When evacuating, it is preferable to follow the procedure below.
The laminated ceramic capacitor 10 is immersed in the electrolytic solution tank 50 containing the electrolytic solution 52 to be used, and the electrolytic solution tank 50 is put into the vacuum chamber. Then, evacuate at room temperature (20 ° C. ± 15 ° C.) at 10 kPa or less for 1 minute or longer. After that, it is released to atmospheric pressure (101 kPa). It is also possible to perform the evacuation in a state where the laminated ceramic capacitor 10 and the conductive shot 60 are put together in the barrel 54.

When applying pressure, it is preferable to follow the procedure below.
The laminated ceramic capacitor 10 is immersed in the electrolytic solution tank 50 containing the electrolytic solution 52 to be used, and the electrolytic solution tank 50 is charged into the pressure chamber. Then, pressurization is performed at room temperature (20 ° C. ± 15 ° C.) at 0.2 MPa or less for 1 minute or more. After that, it is released to atmospheric pressure (101 kPa). When applying pressure, it is also possible to carry out the process in a state where the monolithic ceramic capacitor 10 and the conductive shot 60 are put together in the barrel 54.

Next, a step (S02) of further charging the conductive shot 60 into the barrel 54 and rotating the barrel 54 with the laminated ceramic capacitor 10 immersed in the electrolytic solution 52 is performed. In the step (S01) in which the multilayer ceramic capacitor 10 is charged into the barrel 54, the barrel 54 containing the laminated ceramic capacitor 10 is immersed in the electrolytic solution 52, and vacuum is applied or pressure is applied, the conductive shot 60 is charged. If not, the conductive shot 60 is charged into the barrel 54 into which the multilayer ceramic capacitor 10 is charged. Therefore, in addition to the plurality of multilayer ceramic capacitors 10, a conductive shot 60 is charged in the barrel 54. The rotation speed of the barrel 54 is preferably 3 rpm or more and 30 rpm or less.

As the conductive shot 60, for example, a steel shot, a carbon shot, or the like can be used. It is preferable to use a conductive shot 60 having a diameter of 0.1 mm or more and 10 mm or less.

Next, a step (S03) of applying a positive potential to the electrode rod (anode) 56 provided in the electrolytic solution 52 is performed. An electrode rod (anode) 56 is arranged in the electrolytic solution 52 in which the barrel 54 containing the multilayer ceramic capacitor 10 and the conductive shot 60 is immersed, and a positive potential is applied to the electrode rod (anode) 56. You can do it. The electrode rod (anode) 56 energizes the electrode rod (cathode) 58 through the electrolytic solution 52. It is preferable that the potential applied to the electrode rod (anode) 56 is 2 V or more and 15 V or less, the temperature of the electrolytic solution 52 is normal temperature or more and 50 ° C. or less, and the test time is 10 minutes to 2 hours.

Next, a step (S04) of rotating the barrel 54 with a positive potential applied to the electrode rod (anode) 56 is performed. The barrel 54 containing the monolithic ceramic capacitor 10 and the conductive shot 60 is rotated in the electrolytic solution 52 with a positive potential applied to the electrode rod (anode) 56. As a result, a negative potential is applied from the electrode rod (cathode) 58 to the base electrode layer 26 through the conductive shot 60, and the potential is applied to the internal electrode 16 through the base electrode layer 26. As a result, a redox reaction occurs between the internal electrode 16 and the electrolytic solution 52, and the effect of reducing nickel oxide at the interface between the dielectric layer and the internal electrode can be obtained.

Further, the present invention may include a step (S04A) of swinging the barrel 54. In the step of swinging the barrel 54 (S04A), for example, while rotating the barrel 54, the barrel 54 is not exposed from the liquid level 70 of the electrolytic solution tank 50 in the vertical direction (V direction) or the horizontal direction (H direction). Swing to. It is preferable to swing in the vertical direction (V direction) or the horizontal direction (H direction) at a distance of 1/4 times or more and 2 times or less the diameter of the barrel 54 for 3 or more and 20 or less reciprocations per minute. As a result, the contact efficiency between the monolithic ceramic capacitor 10 and the electrolytic solution 52 is improved, and delamination of defective products is possible in a short time.

Further, the present invention may include a step of pulling up and rotating the barrel 54. In the step of pulling up and rotating the barrel 54, for example, after rotating the barrel 54 for about 10 minutes, the energization is stopped, the barrel 54 is pulled up from the electrolytic solution 52, and the barrel 54 is pulled up from the electrolytic solution 52 in the air at a rotation speed of 3 rpm or more and 30 rpm or less for 1 minute. Rotate. The barrel 54 is immersed in the electrolytic solution 52 again, and the electrode rod (anode) 56 is energized and rotated to perform electrolytic screening. After that, the above operation (step of pulling up and rotating the barrel 54) is repeated. As a result, the electrolytic solution 52 in the vicinity of the laminated ceramic capacitor 10 is updated, and the barrel 54 rotates while being pulled up from the electrolytic solution 52, so that the stirring state of the laminated ceramic capacitor 10 in the barrel 54 changes. When the barrel 54 is immersed in the electrolytic solution 52 again and rotated, for example, a portion that was not in contact with the electrolytic solution 52 before the pulling / rotating operation comes into contact with the electrolytic solution 52. The contact efficiency between the multilayer ceramic capacitor 10 and the electrolytic solution 52 is improved, and delamination of defective products is possible in a short time.

Next, a step (S05) of cleaning the monolithic ceramic capacitor 10 is performed. In the present invention, a positive potential is applied to the electrode rod (anode) 56 for a certain period of time, the barrel 54 is rotated, and then the laminated ceramic capacitor 10 is washed. In the step of cleaning the multilayer ceramic capacitor 10, the energization of the barrel 54 is stopped and the capacitor 54 is pulled up from the electrolytic solution tank 50. The barrel 54 is rotated in the air at a rotation speed of 3 rpm or more and 30 rpm or less for 1 minute. The barrel 54 is immersed in a washing tank containing a washing liquid and rotated at a rotation speed of 3 rpm or more and 30 rpm or less for 1 minute. For example, pure water is used as the cleaning liquid. The barrel 54 is pulled up and rotated in the air at a rotation speed of 3 rpm or more and 30 rpm or less for 1 minute.

Finally, after the cleaning step, a step (S06) of performing electrical characteristic measurement, pressure resistance test or ultrasonic flaw detection test is performed.

In the method for screening a laminated ceramic electronic component of the present invention, it is also possible to perform screening in a state where the base electrode layer 26 and the plating layer 28 are formed on the surface of the base electrode layer 26 as the external electrode 24 of the laminated ceramic electronic component. In order to make the effect of the present invention more remarkable, it is more preferable to perform screening in a state where the plating layer 28 is not formed (a state where only the base electrode layer 26 is formed).

Each method of electrical characteristic measurement, withstand voltage test or ultrasonic flaw detection test is as follows.

(A) Electrical characteristic measurement The electrical characteristic measurement includes capacitance measurement, dielectric loss tangent measurement, and insulation resistance measurement. The details of each measurement method are as follows.
(A) Capacitance measurement Specifically, an AC voltage is applied to the laminated ceramic capacitor 10 using a C meter, and the capacitance is measured.
Since the capacitance value of the delaminated product is lower than that of the non-defective product, only the delaminated product can be screened by setting a threshold value for the capacitance value.
(B) Dissipation factor measurement Specifically, an AC voltage is applied to the laminated ceramic capacitor 10 using an LCR meter to measure the dielectric loss tangent.
Since the dielectric loss tangent value of the delaminated product is higher than that of the non-defective product, only the delaminated product can be screened by setting a threshold value for the dielectric loss tangent value.
(C) Insulation resistance measurement Specifically, a DC voltage is applied to the multilayer ceramic capacitor 10 from a DC power supply, and the leakage current value flowing through the multilayer ceramic capacitor 10 is measured with an ammeter. The insulation resistance value of the monolithic ceramic capacitor 10 is calculated from the leakage current value and the DC voltage value.
Since the insulation resistance value of the delaminated product is lower than that of the non-defective product, only the delaminated product can be screened by setting a threshold value for the insulation resistance value.

(B) Withstand voltage test Specifically, using a DC power supply, a DC voltage exceeding the rating of the multilayer ceramic capacitor 10 is applied to the multilayer ceramic capacitor 10, and only the delaminated product is short-circuited. Then, the insulation resistance value is measured. Since the delamination product that has caused a short circuit has a lower insulation resistance value than the non-defective product, only the delamination product that has caused a short circuit can be screened.

(C) Ultrasonic flaw detection test Specifically, the laminated ceramic capacitors 10 are aligned so that the stacking direction x faces up. The multilayer ceramic capacitor 10 is irradiated with ultrasonic waves in water. The presence or absence of defects is inspected by analyzing the reflected wave.
Since the delaminated product returns the reflected wave earlier than the bottom wave, the delaminated product can be screened based on this difference.

By the above method, in the present invention, in the laminated ceramic capacitor 10 having a potential structural defect such as a void in the inside of the base electrode layer 26 in the external electrode 24 or the inside of the laminated body 12 of the laminated ceramic capacitor 10, the base is used. The plating layer 28 is formed on the electrode layer 26, and the plating solution enters the inside of the laminated body 12 from structural defects such as voids in the base electrode layer 26, and the gap between the internal electrode 16 and the dielectric layer 14 and the laminated body are formed. When the plating solution remains in a structural defect portion such as a potential void of the dielectric layer 14 inside the 12th layer, between the dielectric layers 14 or between the dielectric layer 14 and the internal electrode 16. It is possible to remove the multilayer ceramic capacitor 10 that may be peeled off after plating in advance.

Further, the present invention may include a step (S04A) of swinging the barrel 54. As a result, the contact efficiency between the monolithic ceramic capacitor 10 and the electrolytic solution 52 is improved, and delamination of defective products is possible in a short time.

The electrolytic solution 52 used in the present invention is a neutral aqueous solution or an alkaline aqueous solution, and among them, a neutral metal salt aqueous solution such as sodium sulfate or an alkali metal salt aqueous solution such as sodium carbonate or sodium borate is used. Is preferable. As a result, the delamination phenomenon due to the reduction of nickel oxide is promoted, so that the effect of the present invention can be further ensured.

The present invention is not limited to the above embodiment. That is, various changes can be made to the above-described embodiments with respect to the mechanism, shape, material, quantity, position, arrangement, etc., without departing from the technical idea and scope of the present invention. They are, and they are included in the present invention.

10 Multilayer ceramic capacitors (multilayer ceramic electronic components)
12 Laminated body 12a First main surface 12b Second main surface 12c First side surface 12d Second side surface 12e First end surface 12f Second end surface 14 Dielectric layer 14a Outer layer part 14b Inner layer part 16 Internal electrode 16a First 1 internal electrode 16b 2nd internal electrode 16c floating internal electrode 18 counter electrode part 18a 1st counter electrode part 18b 2nd counter electrode part 20 drawer electrode part 20a 1st drawer electrode part 20b 2nd drawer electrode part 24 External electrode 24a First external electrode 24b Second external electrode 26 Base electrode layer 26a First base electrode layer 26b Second base electrode layer 28 Plating layer 28a First plating layer 28b Second plating layer 50 Electrolysis Tank 52 Electrolyte 54 Barrel 56 Electrode rod (anodee)
58 Electrode rod (cathode)
60 Conductive shot 70 Electrolyte level x Stacking direction y Width direction z Length direction L Length direction z length T Stacking direction x length W Width direction y length H Horizontal direction V Vertical direction R Barrel Direction of rotation C Barrel rotation axis

Claims (7)

A laminate having a plurality of laminated dielectric layers and a plurality of internal electrodes arranged on the dielectric layer.
An external electrode arranged on the surface of the laminate and
Is a screening method for laminated ceramic electronic components with
A step of putting the laminated ceramic electronic component into a barrel, immersing the barrel containing the laminated ceramic electronic component in an electrolytic solution, and performing vacuuming or applying pressure.
A step of further injecting a conductive shot into the barrel and rotating the barrel while the laminated ceramic electronic component is immersed in an electrolytic solution.
The step of applying a positive potential to the electrode rod (anode) provided in the electrolytic solution, and
The process of rotating the barrel with a positive potential applied to the electrode rod (anode), and
The process of cleaning the laminated ceramic electronic components and
After the cleaning step, a step of performing electrical property measurement, pressure resistance test or ultrasonic flaw detection test, and
A method for screening laminated ceramic electronic components. A laminate having a plurality of laminated dielectric layers and a plurality of internal electrodes arranged on the dielectric layer.
An external electrode arranged on the surface of the laminate and
Is a screening method for laminated ceramic electronic components with
A step of putting the laminated ceramic electronic component and a conductive shot into a barrel, immersing the barrel containing the laminated ceramic electronic component in an electrolytic solution, and evacuating or applying pressure.
The process of rotating the barrel while the laminated ceramic electronic component is immersed in the electrolytic solution,
The step of applying a positive potential to the electrode rod (anode) provided in the electrolytic solution, and
The process of rotating the barrel with a positive potential applied to the electrode rod (anode), and
The process of cleaning the laminated ceramic electronic components and
After the cleaning step, a step of performing electrical property measurement, pressure resistance test or ultrasonic flaw detection test, and
A method for screening laminated ceramic electronic components. The method for screening a laminated ceramic electronic component according to claim 1 or 2, wherein only the base electrode layer is formed on the external electrode of the laminated ceramic electronic component. The method for screening a laminated ceramic electronic component according to claim 1 to 3, further comprising a step of swinging the barrel. The method for screening a laminated ceramic electronic component according to claim 1 to 4, wherein the electrolytic solution is a neutral aqueous solution or an alkaline aqueous solution. The method for screening a laminated ceramic electronic component according to claim 5, wherein the neutral aqueous solution of the electrolytic solution is a sodium sulfate aqueous solution. The method for screening laminated ceramic electronic components according to claim 5, wherein the alkaline aqueous solution of the electrolytic solution is a sodium carbonate aqueous solution or a sodium borate aqueous solution.

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