JP6992944B2 - Manufacturing method of laminated ceramic electronic components - Google Patents

Description

The present invention relates to a method for manufacturing a conductive paste for an internal electrode and a laminated ceramic electronic component.

Generally, electronic components using a ceramic material such as a capacitor, an inductor, a piezoelectric element, a varistor or a thermister include a ceramic body made of the ceramic material, an internal electrode formed inside the ceramic body, and the above internal electrode. It is provided with an external electrode installed on the surface of the ceramic body so as to be connected to the ceramic body.

Among the laminated ceramic electronic components, the laminated ceramic capacitor includes a plurality of laminated dielectric layers, an internal electrode arranged to face each other with a single dielectric layer interposed therebetween, and an external electrode electrically connected to the internal electrode. including.

Multilayer ceramic capacitors are widely used as parts of mobile communication devices such as computers, PDAs, and mobile phones because of their small size, high capacity guaranteed, and easy mounting.

In recent years, along with the high performance and lightness, thinness, shortness and miniaturization of the electric and electronic equipment industries, there is a demand for miniaturization, high performance and low cost of electronic parts.

In particular, as CPU speeds, equipment miniaturization and weight reduction, digitization, and high functionality progress, monolithic ceramic capacitors are also becoming smaller, thinner, higher capacity, and lower impedance in the high frequency range. Research and development to realize the characteristics are being actively carried out.

On the other hand, since it is necessary to continuously increase the number of laminated layers per unit volume in order to reduce the size and increase the capacity of the laminated ceramic capacitor, the thickness of the dielectric and the internal electrode needs to be continuously reduced. In order to reduce the thickness of the electrode, it is necessary to suppress sintering so that the conductive metal in the thinly printed coating film does not aggregate during sintering and the electrode connectivity is deteriorated. It is necessary to design the content of the conductive metal optimized for the sintering shrinkage of the metal.

Therefore, under the condition that firing is possible at a temperature of 1050 ° C. or lower and a rapid temperature rise of 1000 ° C. or higher per minute is possible, the electrode thickness should be made as thin as possible in consideration of the shrinkage rate of the chip, and the electrode should be made. The composition of the internal electrode paste that can achieve maximum connectivity is required.

Japanese Unexamined Patent Publication No. 2004-07994

The present invention relates to a method for manufacturing a conductive paste for an internal electrode and a laminated ceramic electronic component.

One embodiment of the present invention is a conductive paste for an internal electrode containing a conductive metal powder and a ceramic powder, and the filling ratio of the conductive metal powder per unit area of the coated coating film is 52% by volume or more. Provided is a conductive paste for an internal electrode.

In another embodiment of the present invention, a step of providing a ceramic green sheet, a step of forming an internal electrode pattern with a conductive paste for an internal electrode containing a conductive metal powder and a ceramic powder, and a step of forming the internal electrode pattern are formed. The internal electrode includes a step of laminating the ceramic green sheets to form a ceramic laminate and a step of firing the ceramic laminate to form a ceramic body including a dielectric layer and an internal electrode. Provided is a method for manufacturing a laminated ceramic electronic component in which the filling ratio of the conductive metal powder per unit area of the pattern is 52% by volume or more.

The internal electrode of the laminated ceramic capacitor to which the conductive paste for the internal electrode according to the embodiment of the present invention is applied can be realized to have excellent connectivity and a thin thickness.

That is, the smaller the size and the higher the number of laminated ceramic capacitors, the thinner the internal electrodes, and the thinner the internal electrodes, the more easily the internal electrodes break during the sintering process, making it difficult to ensure the connectivity of the internal electrodes. However, according to one embodiment of the present invention, the filling ratio of the conductive metal powder per unit area of the coated coating film to which the conductive paste for the internal electrode is applied is adjusted to be 52% by volume or more. The connectivity of the electrodes can be ensured, and a thin-layer internal electrode can be realized.

It is a schematic perspective view which shows the laminated ceramic capacitor which concerns on one Embodiment of this invention. FIG. 3 is a schematic cross-sectional view showing a monolithic ceramic capacitor taken along the I-I'line of FIG. It is an enlarged view of the S area of FIG. It is a graph which shows the addition content of the ceramic powder and the organic substance in the paste which can realize the conductive metal filling ratio of 52% by volume or more in the conductive paste for the internal electrode of the laminated ceramic capacitor which concerns on one Embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the invention can be transformed into various other embodiments, and the scope of the invention is not limited to the embodiments described below. Also, embodiments of the invention are provided to more fully explain the invention to those with average knowledge in the art. Therefore, the shape and size of the elements in the drawings may be exaggerated for a clearer explanation.

One embodiment of the present invention relates to a ceramic electronic component, and the electronic component using the ceramic material includes a capacitor, an inductor, a piezoelectric element, a varistor, a thermistor, and the like. In the following, a monolithic ceramic capacitor will be described as an example of ceramic electronic components.

FIG. 1 is a schematic perspective view showing a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a monolithic ceramic capacitor taken along line I-I'in FIG.

FIG. 3 is an enlarged view of the S region of FIG.

Referring to FIGS. 1 to 3, the laminated ceramic capacitor according to the embodiment of the present invention has a ceramic main body 110, internal electrodes 121 and 122 formed inside the ceramic main body, and outside the ceramic main body 110. External electrodes 131, 132 and the formed can be included.

According to one embodiment of the present invention, the "length direction" of the monolithic ceramic capacitor is defined as the "L" direction in FIG. 1, the "width direction" is defined as the "W" direction, and the "thickness direction" is defined as the "T" direction. Can be done. The above-mentioned "thickness direction" can be used as the same concept as the direction in which the dielectric layers are stacked, that is, the "stacking direction".

The shape of the ceramic body 110 is not particularly limited, but according to one embodiment of the present invention, it may have a hexahedron shape.

The ceramic body 110 can be formed by laminating a plurality of dielectric layers 111.

The plurality of dielectric layers 111 constituting the ceramic body 110 may be in a sintered state, and may be integrated so that the boundaries between adjacent dielectric layers cannot be confirmed.

The dielectric layer 111 can be formed by sintering a ceramic green sheet containing ceramic powder.

The ceramic powder is not particularly limited as long as it is generally used in the art.

Although not limited to this, for example, BaTiO ₃ ceramic powder may be contained.

The BaTIO ₃ ceramic powder is not limited to this, and for example, Ca, Zr and the like are partially dissolved in BaTIO ₃ (Ba _1-x Ca _x ) TiO ₃ and Ba (Ti _1-y ). Ca _y ) O ₃ , (Ba _1-x Ca _x ) (Ti _{1-y Zry} ) O ₃ or Ba (Ti _{1-y Zry} ) O ₃ and the like.

Further, the ceramic green sheet can contain transition metals, rare earth elements, Mg, Al and the like together with the ceramic powder.

The thickness of the monodielectric layer 111 can be appropriately changed according to the capacitance design of the laminated ceramic capacitor.

Although not limited to this, for example, the thickness of the dielectric layer 111 formed between two adjacent internal electrodes after sintering may be 0.6 μm or less.

Internal electrodes 121 and 122 can be arranged inside the ceramic body 110.

The internal electrodes 121 and 122 are formed and laminated on a ceramic green sheet, and can be formed inside the ceramic body 110 with a dielectric layer interposed therebetween by sintering.

The internal electrodes can be a pair of a first internal electrode 121 and a second internal electrode 122 having different polarities from each other, and can be arranged so as to face each other along the stacking direction of the dielectric layer.

As shown in FIG. 2, the ends of the first and second internal electrodes 121 and 122 can be alternately exposed on one surface in the length direction of the ceramic body 110.

Further, although not shown, according to one embodiment of the present invention, the first and second internal electrodes may have a lead portion and may be exposed to the same surface of the ceramic body via the lead portion. Alternatively, the first and second internal electrodes may have a lead portion and may be exposed to one or more surfaces of the ceramic body via the lead portion.

The thickness of the one internal electrodes 121 and 122 is not particularly limited, but may be, for example, 0.5 μm or less.

Alternatively, the thickness of one internal electrode 121, 122 may be 0.1 to 0.5 μm. Alternatively, the thickness of one internal electrode 121, 122 may be 0.3 to 0.5 μm.

According to one embodiment of the present invention, the dielectric layer on which the internal electrodes are formed can be laminated with 200 or more layers.

According to one embodiment of the present invention, the external electrodes 131 and 132 can be arranged on the outside of the ceramic body 110, and the external electrodes 131 and 132 are electrically connected to the internal electrodes 121 and 122. be able to.

More specifically, the first external electrode 131 electrically connected to the first internal electrode 121 exposed on one surface of the ceramic body 110, and the second internal electrode 122 exposed on the other surface of the ceramic body 110 and electricity. It can be composed of a second external electrode connected to the surface.

Further, although not shown, a plurality of external electrodes may be formed in order to be connected to the first and second internal electrodes exposed on the ceramic body.

The external electrodes 131 and 132 can be formed of a conductive paste containing a metal powder.

The metal powder contained in the conductive paste is not particularly limited, and for example, Ni, Cu, or an alloy thereof may be used.

The thicknesses of the external electrodes 131 and 132 can be appropriately determined depending on the intended use, but may be, for example, about 10 to 50 μm.

The internal electrodes 121 and 122 according to the embodiment of the present invention can be formed by applying a conductive paste for an internal electrode containing a conductive metal powder and a ceramic powder.

When the conductive paste for an internal electrode is applied, the filling rate of the conductive metal powder per unit area of the coated coating film is 52% by volume or more.

That is, one embodiment of the present invention is a conductive paste for an internal electrode containing a conductive metal powder and a ceramic powder, and the filling ratio of the conductive metal powder per unit area of the coated coating film is 52% by volume or more. Provided is a conductive paste for an internal electrode.

The conductive metal powder is not particularly limited, and includes, for example, silver (Ag), lead (Pb), platinum (Pt), nickel (Ni), copper (Cu), etc., and these may be used alone or in combination of two or more. May be used.

Further, the conductive metal powder can have various particle sizes depending on the embodiment of the present invention, and may have a particle size of, for example, 50 to 300 nm.

In general, the thickness of the dielectric and the internal electrode needs to continue to decrease because the number of layers per unit volume needs to be continuously increased in order to reduce the size and increase the capacity of the laminated ceramic capacitor.

In order to reduce the thickness of the electrode, it is necessary to suppress sintering so that the conductive metal in the thinly printed coating film does not aggregate during sintering and the electrode connectivity is deteriorated. It is necessary to design the content of the conductive metal optimized for the sintering shrinkage of the metal.

Further, in a high-capacity laminated ceramic capacitor, the thickness of the internal electrode needs to be thin, but the target capacity cannot be realized unless the electrode connectability is excellent.

Further, since the thickness of the internal electrode increases as the electrode connectability decreases, it can be said that the realization of high electrode connectability is indispensable not only for realizing the capacity but also for reducing the thickness.

According to one embodiment of the present invention, it is a conductive paste for an internal electrode containing a conductive metal powder and a ceramic powder, and the filling ratio of the conductive metal powder per unit area of the coated coating film is 52% by volume or more. Since the internal electrode is formed by using a certain conductive paste for the internal electrode, the internal electrode of the laminated ceramic capacitor can be realized to have excellent connectivity and a thin thickness.

When the internal electrode is formed using the conductive paste for the internal electrode according to the embodiment of the present invention, it can be fired at a temperature of 1050 ° C. or lower and can be rapidly heated to 1000 ° C. or higher per minute. Under the conditions, the electrode thickness can be made as thin as possible and the electrode connectivity can be maximized in consideration of the shrinkage rate of the chip.

In the process of manufacturing a multilayer ceramic capacitor, the ceramic body shrinks step by step.

In the step of removing the organic matter or after the firing step, the organic matter is burned and removed, and in this process, the ceramic body shrinks, and in the firing step, the dielectric becomes densified and shrinkage occurs.

Therefore, organic substances are removed from the internal electrodes during the calcination process, narrow shrinkage and rearrangement occur, the conductive metal is sintered during the firing stage, some ceramic additives are trapped, and the remaining ceramic additives are trapped. Escapes to the dielectric.

With reference to FIG. 3, it can be seen that the ceramic additive 11 was trapped inside the internal electrode 121.

However, when a higher firing temperature or a long-term firing step is performed, a conductive metal having a relatively lower sintering temperature than a dielectric, for example, nickel, is overfired and aggregates, so that the electrode The connectivity is reduced and the internal electrodes become thicker in the thickness direction.

Therefore, when the firing temperature is as high as 1100 ° C. or higher, the effect of suppressing sintering by the ceramic additive is greater than the filling rate of the conductive metal powder in the conductive paste state for internal electrodes.

However, when low temperature and high speed firing are possible, the filling factor of the conductive metal has a great influence on the electrode connectivity in the composition of the conductive paste for the internal electrode, and has a great influence on the thinning of the thickness of the internal electrode. Will exert.

Shrinkage in the length and width directions of the ceramic body to which the fine-grained barium titanate additive, which has been sintered with a green chip laminated with a ceramic green sheet coated with a conductive paste for internal electrodes, is applied, is approximately 21%. The shrinkage rate in the thickness direction is about 17%.

Therefore, the ceramic body that has been sintered undergoes shrinkage of about 42%.

According to one embodiment of the present invention, the composition of the conductive paste for the internal electrode is determined in consideration of the shrinkage rate of the ceramic body for which the sintering is completed, and the conductive metal powder is used per unit area of the coated coating film. Provided is a conductive paste for an internal electrode having a filling ratio of 52% by volume or more.

Since the internal electrode is formed by using the conductive paste for the internal electrode, the internal electrode of the laminated ceramic capacitor can be realized to have excellent connectivity and a thin thickness.

Specifically, when the internal electrode of the laminated ceramic capacitor is formed by using the conductive paste for the internal electrode according to the embodiment of the present invention, the internal electrode is as thin as possible after firing and the electrode connectivity is close to 100%. Can be realized.

Further, when the internal electrode is formed by using the conductive paste for the internal electrode according to the embodiment of the present invention, it can be fired at a temperature of 1050 ° C. or lower, and a rapid temperature rise of 1000 ° C. or higher per minute can be achieved. Under possible conditions, the electrode thickness can be made as thin as possible and the electrode connectivity can be maximized in consideration of the shrinkage rate of the chip.

FIG. 4 is a graph showing the added content of ceramic powder and organic substances in the paste capable of achieving a conductive metal filling ratio of 52% by volume or more in the conductive paste for the internal electrode of the laminated ceramic capacitor according to the embodiment of the present invention. be.

Referring to FIG. 4, the additive content of the ceramic powder and the organic substance in the paste capable of realizing the conductive metal filling rate of 52% by volume or more in the conductive paste for the internal electrode is the content of the organic substance (y) = −0. 19 × Ceramic powder content (x) + 11.11 is satisfied.

More specifically, the additive content of the ceramic powder and the organic substance in the paste that can realize the conductive metal filling ratio of 52% by volume or more in the conductive paste for the internal electrode is 5 to 15% by weight of the above ceramic powder. The organic substance has a content of 8% by weight or more.

When the content of the ceramic powder is less than 5% by weight, there is a problem that the electrode connectivity is reduced due to the decrease in the sintering shrinkage suppressing force under the process conditions of rapid temperature rise.

On the other hand, when the content of the ceramic powder is 15% by weight or more, the content of the organic substance for ensuring the conductive metal filling rate becomes relatively too small, so that the dispersibility and printability are improved. There is a problem that the electrode connectivity is reduced after sintering due to the decrease.

Therefore, the content of the ceramic additive powder is 5 to 15% by volume with respect to the conductive metal powder, thereby achieving a conductive metal filling rate of 52% by volume or more in the conductive paste for internal electrodes. can do.

The ceramic powder is added to control the sintering shrinkage of the conductive metal powder, and is not limited as long as it is generally used, for example, barium titanate (BaTIO ₃ ) or the like. be.

On the other hand, when the content of the organic substance is less than 8% by weight, there is a problem that the electrode connectivity is reduced after sintering due to the decrease in dispersibility and printability.

In another embodiment of the present invention, a step of providing a ceramic green sheet, a step of forming an internal electrode pattern with a conductive paste for an internal electrode containing a conductive metal powder and a ceramic powder, and a step of forming the internal electrode pattern are formed. The internal electrode includes a step of laminating the ceramic green sheets to form a ceramic laminate and a step of firing the ceramic laminate to form a ceramic body including a dielectric layer and an internal electrode. Provided is a method for manufacturing a laminated ceramic electronic component in which the filling ratio of the conductive metal powder per unit area of the pattern is 52% by volume or more.

Hereinafter, a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention will be described.

According to one embodiment of the present invention, a plurality of ceramic green sheets can be provided. The ceramic green sheet can be produced by mixing ceramic powder, a binder, a solvent and the like to produce a slurry, and the slurry can be produced into a sheet having a thickness of several μm by a doctor blade method.

The ceramic green sheet can be subsequently sintered to form the monodielectric layer 111 as shown in FIG.

Next, the conductive paste for internal electrodes can be applied onto the ceramic green sheet to form an internal electrode pattern.

The internal electrode pattern can be formed by a screen printing method or a gravure printing method.

The conductive paste for an internal electrode is a paste according to an embodiment of the present invention, and the composition is determined so that the filling ratio of the conductive metal powder per unit area of the internal electrode pattern is 52% by volume or more. be able to.

Next, the ceramic green sheet on which the internal electrode pattern is formed can be laminated, pressed from the stacking direction, and crimped.

This makes it possible to manufacture a ceramic laminate on which an internal electrode pattern is formed.

Next, the ceramic laminate can be cut into chips by cutting each region corresponding to one capacitor.

At this time, one end of the internal electrode pattern can be cut so as to be alternately exposed on the side surface.

Next, the chipped laminate can be fired to produce a ceramic body.

As described above, the firing step can be performed in a reducing atmosphere.

Further, the firing step can be performed by adjusting the temperature rising rate, and the firing is not limited to this, but the firing of the ceramic laminate is performed at a temperature of 1050 ° C. or lower and 1000 ° C./min or higher. It may be done at speed.

Next, the outer electrode can be formed so as to cover the side surface of the ceramic body and to be electrically connected to the internal electrode exposed on the side surface of the ceramic body. After that, a plating layer such as nickel or tin can be formed on the surface of the external electrode.

According to one embodiment of the present invention, the connectability of the internal electrodes may be 93% or more.

According to one embodiment of the present invention, the connectivity of the internal electrode is the ratio of the length of the portion where the internal electrode is actually formed to the total length of the internal electrode (total length of the internal electrode / the portion where the internal electrode is actually formed). Can be defined by (length of).

The total length of the internal electrode and the length of the portion where the internal electrode is actually formed can be measured by using an optical image obtained by scanning a cross section of the laminated ceramic capacitor as described above.

More specifically, in an image obtained by scanning a cross section in the length direction cut at the central portion in the width direction of the ceramic body, the ratio of the length of the portion where the internal electrode is actually formed to the total length of the internal electrode is measured. Can be done.

In one embodiment of the present invention, the total length of the internal electrode can mean the length including the gap formed between the internal electrodes in one internal electrode, and the length of the portion where the internal electrode is actually formed. And can mean a length other than the gap formed between the internal electrodes in one internal electrode.

As described above, the gap means pores penetrating the internal electrode, and does not include pores formed only on a part of the surface of the internal electrode or inside the internal electrode.

According to one embodiment of the present invention, the actual length of the internal electrode can be measured by subtracting the length of the gap from the total length (T) of the internal electrode.

According to one embodiment of the present invention, the thickness of one internal electrode 121, 122 may be 0.5 μm or less.

Alternatively, the thickness of one internal electrode 121, 122 may be 0.1 to 0.5 μm. Alternatively, the thickness of one internal electrode 121, 122 may be 0.3 to 0.5 μm.

According to one embodiment of the present invention, as shown in Table 1 below, the contents of the ceramic powder and the organic substance, the filling rate of the conductive metal, the coating thickness, the electrode connectivity and the electrode thickness were compared.

Referring to Table 1 above, Samples 1, 2, 4, 9, and 10 are cases where the numerical range of the present invention is not satisfied, and there is a problem in the connectivity of the internal electrodes, and the samples are considered to be defective or partially defective. Shown.

On the other hand, Samples 3 and 5 to 8 were cases where the numerical range of the present invention was satisfied, and the connectivity of the internal electrodes was 93% or more, which was judged to be good.

Therefore, according to one embodiment of the present invention, the connectability of the internal electrodes is improved, and a high-capacity laminated ceramic capacitor can be realized.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to this, and various modifications and modifications are made within the scope of the technical idea of the present invention described in the claims. It is clear to those with ordinary knowledge in the art that this is possible.

110 Ceramic body 111 Dielectric layer 121, 122 Internal electrode 131, 132 External electrode 11 Ceramic additive

Claims (4)

At the stage of installing the ceramic green sheet,
At the stage of forming an internal electrode pattern with a conductive paste for internal electrodes containing conductive metal powder and ceramic powder,
At the stage of laminating the ceramic green sheets on which the internal electrode pattern is formed to form a ceramic laminate,
The ceramic laminate includes a step of firing a ceramic body to form a ceramic body including a dielectric layer and an internal electrode, and the filling rate of the conductive metal powder of the internal electrode pattern is 52% by volume or more.
The ceramic powder has a content of 5 to 15% by weight and has a content of 5 to 15% by weight.
The conductive paste for internal electrodes further contains an organic substance having a content of 8% by weight or more.
The connectability of the internal electrode defined by the ratio of the length of the actual internal electrode to the total length of the internal electrode is 93% or more.
Manufacturing method of laminated ceramic electronic components. The conductive metal powder is nickel, and the ceramic powder has a content of 10 to 15% by weight based on the weight of the nickel.
The method for manufacturing a laminated ceramic electronic component according to claim 1, wherein the conductive paste for an internal electrode further contains an organic substance having a content of 8% by weight or more and 9.21% by weight or less with respect to the weight of the nickel. The method for manufacturing a laminated ceramic electronic component according to claim 1 or 2, wherein the thickness of the internal electrode is 0.5 μm or less. The method for manufacturing a laminated ceramic electronic component according to any one of claims 1 to 3, wherein the ceramic laminate is fired at a temperature of 1050 ° C. or lower and a speed of 1000 ° C./min or more.

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