Reduction-resistant dielectric ceramic compact and laminated ceramic capacitor

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to reduction-resistant dielectric ceramic compacts and laminated ceramic capacitors comprising dielectric ceramic layers formed of the reduction-resistant dielectric ceramic compacts, and more particularly, relates to a laminated ceramic capacitor which is advantageously used in a high-frequency AC region or in an intermediate to high DC voltage range and which comprises internal electrodes formed of a base metal, and to a reduction-resistant dielectric ceramic compact for forming dielectric ceramic layers for use in the laminated ceramic capacitor.

2. Description of the Related Art

Heretofore, laminated ceramic capacitors are generally manufactured in a manner as described below.

First, ceramic green sheets, which contain a dielectric material and are coated with an electrode material for forming internal electrodes, are prepared for forming dielectric ceramic layers. As the dielectric material, a material primarily composed of, for example, BaTiO.sub.3 is used. Next, the ceramic green sheets coated with this electrode material are laminated to each other and are then bonded together by thermo-compression bonding, and the laminate thus formed is fired, thereby yielding a ceramic laminate having the internal electrodes. Subsequently, external electrodes, which are electrically connected to the internal electrodes, are provided on end surfaces of this ceramic laminate by firing, whereby a laminated ceramic capacitor is obtained.

Consequently, a material which is not oxidized during firing of a ceramic laminate has been generally selected as the material used for the internal electrodes. For example, noble metals, such as platinum, gold, palladium and a silver-palladium alloy, have been used as the materials for the internal electrodes. However, even though these internal electrode materials have superior characteristics, since they are significantly expensive, these materials are most responsible for an increase in manufacturing cost of the laminated ceramic capacitors.

Accordingly, a laminated ceramic capacitor has been proposed which uses a relatively inexpensive base metal such as nickel or copper as the internal electrode material in order to reduce the manufacturing cost.

However, these base metals mentioned above are easily oxidized at a high temperature in an oxidizing atmosphere, and as a result, they cannot serve as the internal electrodes. In order to use a base metal as the internal electrodes for the laminated ceramic capacitor, firing for obtaining the laminated ceramic capacitor must be performed in a neutral or a reducing atmosphere.

In addition, when firing is performed at a low partial pressure of oxygen in the neutral or the reducing atmosphere described above, the ceramic compact for forming dielectric ceramic layers is significantly reduced, and as a result, a problem may occur in that the ceramic compact starts to have semiconductor characteristics.

Accordingly, as a reduction-resistant dielectric ceramic compact which is not likely to have semiconductor characteristics even though fired at a low partial pressure of oxygen for preventing oxidation of a base metal, for example, a BaTiO.sub.3 -(Mg,Zn,Sr,Ca)O-B.sub.2 O.sub.3 -SiO.sub.2 -based dielectric ceramic compact disclosed in Japanese Examined Patent Application Publication No. 61-14611, a (Ba,M,L)(Ti,R)O.sub.3 -based dielectric ceramic compact (in which M is Mg or Zn, L is Ca or Sr, and R is Sc, Y, or a rare earth element) disclosed in Japanese Unexamined Patent Application Publication No. 7-272971, and the like have been proposed.

Concomitant with trends toward higher integration, improved performance and lower price of electronic devices, laminated ceramic capacitors are increasingly subject to more adverse usage conditions, and hence, lower loss, improved insulating characteristics, improved breakdown voltages, improved reliability, larger capacity, lower price and the like are strongly required for the laminated ceramic capacitors.

In addition, laminated ceramic capacitors which can be used under high frequency conditions of high voltage or large current are increasingly in demand in recent years. The important properties required for these laminated ceramic capacitor are low loss and low heat generation. The reason for this is that when the loss and heat generation are large, the life of the laminated ceramic capacitor itself is decreased. Furthermore, due to the loss and the heat generation of the laminated ceramic capacitor, an increase in temperature occurs in the circuit containing them, and as a result, malfunctions of peripheral units and a decrease in life thereof also occur.

The laminated ceramic capacitors are also increasingly used under high DC voltage conditions. However, particularly in conventional laminated ceramic capacitors using nickel as an internal electrode material which are designed to be used under relatively low electric field conditions, when used under high electric field conditions, the insulating characteristics, breakdown voltage and reliability are degraded.

When a laminated ceramic capacitor is formed by using the dielectric ceramic compact disclosed in Japanese Examined Patent Application Publication No. 61-14611 or Japanese Unexamined Patent Application Publication No. 7-272971, even though the rate of change in static capacitance with temperature is not significant, there are shortcomings in that the loss and the heat generation are significant when used under high frequency conditions of high voltage or large current. In addition, since the dielectric ceramic compact described above is reduction-resistant, a base metal such as nickel can be used as the internal electrode material when firing at a low partial pressure of oxygen is performed; however, the firing at a low partial pressure of oxygen is hard firing for the dielectric ceramic compact, and for example, when an obtained laminated ceramic capacitor is used under high DC voltage conditions, there are shortcomings in that the insulating resistance is low and that the reliability is poor.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a reduction-resistant dielectric ceramic compact for advantageously forming dielectric ceramic layers for use in, for example, a laminated ceramic capacitor, which has a low loss and low heat generation when used under high frequency conditions of high voltage or large current, and which exhibits a stable insulating resistance under AC or DC high temperature loading conditions.

Another object of the present invention is to provide, in addition to the object described above, a laminated ceramic capacitor which can use a base metal such as nickel or a nickel ally as an internal electrode material.

A reduction-resistant dielectric ceramic compact of the present invention comprises an auxiliary sintering agent and a solid solution comprising a barium titanate-based perovskite compound represented by the formula ABO.sub.3 as a primary component.

In the reduction-resistant dielectric ceramic compact, the crystalline axis ratio c/a obtained by x-ray diffraction in a temperature range of -25.degree. C. or above satisfies 1.000.ltoreq.c/a.ltoreq.1.003, and the maximum peak for temperature dependence of the dielectric constant measured at an electric strength of 2 Vrms/mm or less and at an AC frequency of 1 kHz is present at a temperature of below -25.degree. C.

The primary component described above is represented by the formula ABO.sub.3 +aR+bM.

In this formula described above, R is a compound containing at least one element selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, M is a compound containing at least one element selected from the group consisting of Mn, Ni, Mg, Fe, Al, Cr and Zn, and a and b indicate the number of moles of the compounds mentioned above in the chemical formula each containing one element among the elements mentioned above.

In addition, in the formula described above, preferably 1.000<A/B.ltoreq.1.035, 0.005.ltoreq.a.ltoreq.0.12, and 0.005.ltoreq.b.ltoreq.0.12.

In the reduction-resistant dielectric ceramic compact of the present invention, about 0.2 to 4.0 parts by weight of the auxiliary sintering agent is preferably present with respect to 100 parts by weight of the primary component.

In addition, the primary component preferably comprises X(Zr,Hf)O.sub.3 in the reduction-resistant dielectric ceramic compact of the present invention, in which X is at least one element selected from the group consisting of Ba, Sr and Ca. X(Zr,Hf)O.sub.3 can range of from zero to about 0.20 mole with respect to 1 mole of ABO.sub.3 in the primary component.

In the reduction-resistant dielectric ceramic compact of the present invention, the primary component preferably comprises D which is a compound containing at least one element selected from the group consisting of V, Nb, Ta, Mo, W, Y, Sc, P, Al, and Fe. In the case described above, D in the range of from zero to 0.02 mole is more preferably contained with respect to 1 mole of ABO.sub.3 in the primary component.

In the reduction-resistant dielectric ceramic compact of the present invention, the primary component may comprise X(Zr,Hf)O.sub.3 and D. With respect to 1 mole of ABO.sub.3 in the primary component, it is preferable that X(Zr,Hf)O.sub.3 be in the range of from zero to about 0.20 mole and the D be contained in the range of from zero to about 0.02 mole.

In the reduction-resistant dielectric ceramic compact of the present invention, when the barium titanate-based perovskite compound represented by ABO.sub.3 is represented by the chemical formula {(Ba.sub.1-x-y Sr.sub.x Ca.sub.y)O}.sub.m TiO.sub.2, x, y and m preferably satisfy 0.ltoreq.x+y.ltoreq.0.20 and 1.000<m.ltoreq.1.035, and with respect to 100 parts by weight of the barium titanate-based perovskite compound, it is preferable that compounds comprising at least one element selected from the group consisting of S, Na and K be in the range of about 0.5 part by weight or less calculated as SO.sub.3, Na.sub.2 O and K.sub.2 O, respectively, and comprising Cl be in the range of about 5 parts by weight or less.

In the reduction-resistant dielectric ceramic compact of the present invention, the auxiliary sintering agent preferably comprises a compound containing boron, a compound containing silicon and a compound containing boron and silicon. In particular, the compound containing silicon is preferably silicon oxide.

The present invention may be applied to a laminated ceramic capacitor comprising a plurality of dielectric ceramic layers, internal electrodes formed between the dielectric ceramic layers and external electrodes electrically connected to the internal electrodes. In the laminated ceramic capacitor described above, the dielectric ceramic layers comprise the reduction-resistant dielectric ceramic compact according to the present invention described above.

In the laminated ceramic capacitor of the present invention, the internal electrodes may be formed of nickel, a nickel alloy, copper or a copper alloy.

In addition, in the laminated ceramic capacitor of the present invention, the external electrodes may each comprise a first layer composed of a sintered layer containing a powdered conductive metal or of a sintered layer containing a powdered conductive metal and one of a glass frit, a crystallized glass and a ceramic; and a second layer which is disposed on the first layer and which is a plating layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a laminated ceramic capacitor according to an embodiment of the present invention; and

FIG. 2 is an exploded perspective view showing a ceramic laminate provided for the laminated ceramic capacitor shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a cross-sectional view showing a laminated ceramic capacitor 1 according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view showing a ceramic laminate 3 provided for the laminated ceramic capacitor 1 shown in FIG. 1.

The laminated ceramic capacitor 1 comprises the ceramic laminate 3 in the form of a rectangular parallelepiped obtained by laminating a plurality of dielectric ceramic layers 2a and 2b with internal electrodes 4 provided therebetween. On the two end surfaces of the ceramic laminate 3, external electrodes 5 are formed so as to be connected to predetermined internal electrodes 4, and on each external electrode 5, a first plating layer 6 composed of nickel, copper or the like is formed, and in addition, on each first plating layer 6, a second plating layer 7 composed of solder, tin or the like is formed.

Next, a method for manufacturing this laminated ceramic capacitor 1 will be described in the order of manufacturing steps.

First, a powdered barium titanate-based starting material, which is used as a primary component of the dielectric ceramic layers 2a and 2b, is prepared by weighing and mixing materials so as to have a predetermined composition. The composition of the powdered starting material will be described later.

Next, an organic binder is added to the powdered starting material thus formed so as to form a slurry and the slurry is molded to form sheets, thereby yielding ceramic green sheets for forming the dielectric ceramic layers 2a and 2b.

Subsequently, on one major surface of each ceramic green sheet used for the dielectric ceramic layer 2b, an internal electrode 4 is formed which contains a base metal, such as nickel, a nickel alloy, copper or a copper alloy, as a conductive component. These internal electrodes 4 may be formed by a printing method such as a screen printing method or may be formed by a deposition method or a plating method.

Next, the required number of ceramic green sheets for forming dielectric ceramic layers 2b provided with the internal electrodes 4 formed thereon are laminated to each other, and as shown in FIG. 2, these green sheets are provided between ceramic green sheets for forming dielectric ceramic layers 2a provided with no internal electrodes formed thereon and are bonded by compression, thereby yielding a green laminate.

Subsequently, the green laminate is fired at a predetermined temperature in a predetermined atmosphere, thereby yielding the ceramic laminate 3.

Next, on the two end surfaces of the ceramic laminate 3, the external electrodes 5 are formed so as to be electrically connected to predetermined internal electrodes 4. As a material for this external electrode 5, the same material as that for the internal electrode 4 may be used. In addition, silver, palladium, a silver-palladium alloy, copper, a copper alloy or the like may also be used, and in addition, a material may be used which is obtained by adding a glass frit, such as a B.sub.2 O.sub.3 -SiO.sub.2 -BaO-based glass or a Li.sub.2 O-SiO.sub.2 -BaO-based glass, a crystallized glass or a ceramic to the powdered metal mentioned above. In view of application of the laminated ceramic capacitor 1, the place at which the capacitor is used and like considerations, an appropriate material may be selected. In addition, the external electrode 5 is typically formed by steps of coating the ceramic laminate 3 obtained by firing with a paste containing a powdered metal and baking; however, the paste may be applied to the laminate before firing and may then be simultaneously fired with the ceramic laminate 3.

Subsequently, on the external electrodes 5, plating is performed using nickel, copper or the like so as to form the first plating layers 6. Finally, on these first plating layers 6, the second plating layers 7 composed of solder or tin are formed, whereby the laminated ceramic capacitor 1 is completed. In this connection, conductive layers further formed on the external electrodes 5 by plating or the like may be omitted depending on application of the laminated ceramic capacitor.

By firing the powdered barium titanate-based starting material for forming the dielectric ceramic layers 2a and 2b described above, the reduction-resistant dielectric ceramic compact, which comprises the auxiliary sintering agent and the solid solution comprising barium titanate as the primary component, is obtained as described above.

In this reduction-resistant dielectric ceramic compact, the crystalline axis ratio c/a obtained by x-ray diffraction in a temperature range of -25.degree. C. or above satisfies 1.000.ltoreq.c/a.ltoreq.1.003, and in temperature dependence of a relative dielectric constant measured at an electric strength of 2 Vrms/mm or less and at an AC frequency of 1 kHz, the maximum peak is present at -25.degree. C. or below.

In addition, the primary component is represented by the formula ABO.sub.3 +aR+bM.

In this formula, ABO.sub.3 is a barium titanate-based perovskite compound having an A-site element and a B-site element. R is a compound containing at least one element selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. M is a compound containing at least one element selected from the group consisting of Mn, Ni, Mg, Fe, Al, Cr and Zn. In addition, a and b each indicates the number of moles of the compound described above in the formula.

In addition, 1.000<A/B.ltoreq.1.035, 0.005.ltoreq.a.ltoreq.0.12, and 0.005.ltoreq.b.ltoreq.0.12.

By using the reduction-resistant dielectric ceramic compact described above for forming the dielectric ceramic layers 2a and 2b, in the laminated ceramic capacitor 1 thus obtained, the loss and the heat generation under high frequency conditions of high voltage or large current can be decreased, and in addition, the insulating resistance can be stabilized under AC or DC high temperature loading conditions. Furthermore, a base metal such as nickel or a nickel alloy can be satisfactory used as the material for the internal electrode 4.

The content of the auxiliary sintering agent contained in this reduction-resistant dielectric ceramic compact is preferably in the range of about 0.2 to 4.0 parts by weight with respect to 100 parts by weight of the primary component, and more preferably, in the range of about 0.5 to 2 parts by weight. When the content is less than about 0.2 part by weight, insufficient sintering may occur in the fired reduction-resistant dielectric ceramic compact in some cases, and on the other hand, when the content is more than about 4.0 parts by weight, the average life time of the laminated ceramic capacitor 1 in a high temperature loading test may be decreased in some cases.

As the auxiliary sintering agent, for example, a compound containing boron, a compound containing silicon or a compound containing boron and silicon is used. In particular, as the compound containing silicon, silicon oxide is advantageously used.

In addition, when the primary component comprises X(Zr, Hf)O.sub.3 (in which X is at least one element selected from the group consisting of Ba, Sr and Ca) and/or D (in which D is a compound containing at least one element selected from the group consisting of V, Nb, Ta, Mo, W, Y, Sc, P, Al and Fe), the features described above can be further improved. In this case, it is preferable that X(Zr, Hf)O.sub.3 be in the range of from zero to about 0.20 mole and that D be in the range of from zero to about 0.02 mole with respect to 1 mole of ABO.sub.3 in the primary component.

The ratio of Zr to Hf in the X(Zr, Hf) described above is not specifically limited; however, in order to obtain superior sintering characteristics, the ratio of Hf is preferably about 30 mole percent or less.

In the barium carbonate and titanium oxide which are used for forming this reduction-resistant dielectric ceramic compact, S, Na, K, Cl and the like are contained as impurities. When the barium titanate-based perovskite compound represented by ABO.sub.3 is represented by the chemical formula {(Ba.sub.1-x-y Sr.sub.x Ca.sub.y)O}.sub.m TiO.sub.2, it is preferable that x, y, and m satisfy 0.ltoreq.x+y.ltoreq.0.2 and 1.000<m.ltoreq.1.035. In addition, with respect to 100 parts by weight of this barium titanate-based perovskite compound, it is preferably that compounds containing at least one element selected from the group consisting of S, Na and K contain about 0.5 part by weight or less thereof as SO.sub.3, Na.sub.2 O, and K.sub.2 O, respectively, and that about 5 parts by weight or less of Cl is present. When S, Na, K and Cl are contained in greater amounts in the parts by weight mentioned above, the sintering may vary, resulting in variation in capacitance of the laminated ceramic capacitor 1.

By using the reduction-resistant dielectric ceramic compact described above for forming the dielectric ceramic layers 2a and 2b in the obtained laminated ceramic capacitor 1, the loss and the heat generation can be decreased under high frequency conditions of high voltage or large current, and in addition, the insulating resistance can be stabilized under AC or DC high temperature loading conditions. Furthermore, a base metal such as nickel or a nickel alloy can be satisfactory used as the internal electrode material 4.

Next, the reduction-resistant dielectric ceramic compact and the laminated ceramic capacitor according to the present invention will be described in more detail with reference to examples.

EXAMPLE 1

In this example, reduction-resistant dielectric ceramic compacts having a composition represented by the formula {(Ba.sub.1-x-y Sr.sub.x Ca.sub.y)O}.sub.m TiO.sub.2 +aR+bM are to be obtained.

First, as starting materials, powdered BaCO.sub.3, CaCO.sub.3, SrCO.sub.3 and TiO.sub.2 were prepared each having a purity of 98%.

Next, the powdered starting materials described above were weighed so that {(Ba.sub.1-x-y Sr.sub.x Ca.sub.y)O}.sub.m TiO.sub.2, a type of barium titanate-based solid solution represented by ABO.sub.3 showing a perovskite structure, had a composition in which the molar ratios of x, y, and m were in accordance with those shown in Table 1. Subsequently, the starting materials thus weighed were wet-mixed by using a ball mill, and after pulverizing and drying were performed, calcining was performed at 1,120.degree. C. for 2 hours in the air, whereby a barium titanate-based solid solution was obtained.

As a starting material for R (in which R was a compound containing at least one element selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), powdered La.sub.2 O.sub.3, CeO.sub.2, Pr.sub.6 O.sub.11, Nd.sub.2 O.sub.3, Sm.sub.2 O.sub.3, EU.sub.2 O.sub.3, Gd.sub.2 O.sub.3, Tb.sub.4 O.sub.7, Dy.sub.2 O.sub.3, Ho.sub.2 O.sub.3, Er.sub.2 O.sub.3, Tm.sub.2 O.sub.3, Yb.sub.2 O.sub.3 and Lu.sub.2 O.sub.3 were prepared each having a purity of 99% or more.

As a starting material for M (in which M is a compound containing at least one element selected from the group consisting of Mn, Ni, Mg, Fe, Al, Cr and Zn), powdered MnO, NiO, MgO, Fe.sub.2 O.sub.3, Al.sub.2 O.sub.3, Cr.sub.2 O.sub.3 and ZnO were prepared each having a purity of 99% or more.

As an auxiliary sintering agent, four types described below were prepared.

Oxides, carbonate salts and hydroxides for individual components were weighted, mixed and pulverized so that, first, a 0.55B.sub.2 O.sub.3 -0.25Al.sub.2 O.sub.3 -0.03MnO-0.17BaO (hereinafter referred to as an auxiliary sintering agent 1) was obtained as an example of a compound containing boron; secondly, 0.25Li.sub.2 O-0.65(0.3TiO.sub.2.0.7SiO.sub.2)-Al.sub.2 O.sub.3 (hereinafter referred to as an auxiliary sintering agent 2) was obtained as an example of a compound containing silicon; and thirdly, 0.25Li.sub.2 O-0.30B.sub.2 O.sub.3 -0.03TiO.sub.2 -0.42SiO.sub.2 (hereinafter referred to as an auxiliary sintering agent 3) was obtained as an example of a compound containing silicon and boron; whereby powdered materials were obtained. After the powdered materials thus obtained were each heated to 1,500.degree. C. in a platinum crucible, by quenching and pulverizing, individual powdered oxides having an average particle diameter of 1 .mu.m or less were obtained. In addition, fourthly, as another example of a compound containing silicon, a colloidal silica solution (hereinafter referred to as an auxiliary sintering agent 4) containing 30 wt % of silicon oxide as SiO.sub.2 was obtained.

Next, the barium titanate-based solid solutions thus prepared and the starting materials for the other components were weighed so as to obtain the compositions shown in Table 1.

In Table 1, the factor a for R and the factor b for M indicates the number of moles of each in the chemical formula. Furthermore, the content of the auxiliary sintering agent is represented by the parts by weight with respect to 100 parts by weight of the primary component {(Ba.sub.1-x-y Sr.sub.x Ca.sub.y)O}.sub.m TiO.sub.2 +aR+bM.

TABLE 1 Auxiliary Sintering Agent Sample a(Molar Ratio) Total b(Molar Ratio) Total (Parts by Weight) No. x y x + y R(Oxide of Element) of a M(Oxide of Element) of b m 1 2 3 4 1 0 0 0 Eu 0.05 Yb 0.05 0.1 Mg 0.05 Mn 0.05 0.1 1.000 0 2 0 0 2 0.05 0.05 0.1 Gd 0.08 0.08 Mn 0.1 0.1 1.055 4 0 0 0 3 0 0.05 0.05 Nd 0.003 0.003 Ni 0.005 0.005 1.010 0 0 0 2 4 0.1 0.08 0.18 Gd 0.1 Ho 0.05 0.15 Mg 0.05 Ni 0.05 0.1 1.015 0 0 0 3 5 0.04 0.08 0.12 Tb 0.01 0.01 Fe 0.001 Mn 0.002 0.003 1.010 1 0 0 0 6 0 0.08 0.08 Eu 0.05 Ce 0.05 0.1 Al 0.10 Mg 0.04 0.14 1.005 0 0.5 0 0 7 0 0 0 Tb 0.09 0.09 Mg 0.05 Mn 0.05 0.1 1.030 0.15 0 0 0 8 0.01 0.04 0.05 Dy 0.03 Pr 0.03 0.06 Cr 0.04 Mg 0.04 0.08 1.020 0 5 0 0 9 0.02 0.23 0.25 Gd 0.04 0.04 Fe 0.005 Mg 0.045 0.05 1.010 0 0 1 0 10 0 0 0 Sm 0.08 Tm 0.01 La 0.02 0.11 Mn 0.05 Mg 0.05 0.1 1.035 0 0 0 4 11 0.01 0.04 0.05 Gd 0.004 Tb 0.001 0.005 Mg 0.01 0.01 1.010 0 2 0 0 12 0.05 0.05 0.1 Gd 0.1 Dy 0.02 0.12 Mg 0.04 Ni 0.03 Al 0.03 0.1 1.015 0 0 2 0 13 0.04 0.05 0.09 Tb 0.04 Nd 0.02 0.06 Mn 0.005 0.005 1.010 1 0 0 0 14 0.12 0 0.12 Er 0.03 Yb 0.03 Lu 0.02 0.08 Al 0.02 Mg 0.05 Ni 0.05 0.12 1.015 0 0 0 2 15 0.1 0.04 0.14 Sm 0.06 Lu 0.02 0.08 Cr 0.02 Mn 0.03 0.05 1.020 0 0 0.2 0 16 0 0 0 Tb 0.05 Ce 0.01 0.06 Mg 0.07 0.07 1.010 0 0 4 0 17 0.1 0.1 0.2 Gd 0.07 Ho 0.02 0.09 Mn 0.1 0.1 1.015 3 0 0 0 18 0.03 0.1 0.13 Dy 0.1 0.1 Zn 0.05 Mg 0.05 0.1 1.010 0 2 0 0

Next, a polyvinyl butyral-based binder and an organic solvent such as ethanol were added to each of the mixtures prepared for forming the samples described above and each mixture was then wet-mixed by using a ball mill, thereby forming a slurry. The ceramic slurry was then sheet-molded by the doctor blade method, thereby obtaining rectangular ceramic green sheets 25 .mu.m thick.

Next, a conductive paste primarily composed of nickel was printed on predetermined ceramic green sheets, whereby conductive paste layers for forming internal electrodes were formed.

Subsequently, the ceramic green sheets provided with the conductive paste layers formed thereon were laminated to each other so that the sides, at which the conductive paste layers extend, of ceramic green sheets adjacent to each other were opposite to each other, and ceramic green sheets having no conductive paste layers formed thereon were placed on the top and the bottom of the laminate thus formed and were then bonded together by compression, whereby a green laminate was obtained.

Next, the green ceramic laminate was heated to 350.degree. C. in a nitrogen atmosphere so as to remove the binder and was then fired at a temperature shown in Table 2 for 2 hours in a reducing atmosphere composed of a H.sub.2 -N.sub.2 -H.sub.2 O gas at an oxygen partial pressure of 10.sup.-9 to 10.sup.-12 MPa, whereby a sintered ceramic laminate was obtained.

Subsequently, both end surfaces of the sintered ceramic laminate were coated with a conductive paste composed of a B.sub.2 O.sub.3 -Li.sub.2 O-SiO.sub.2 -BaO-based glass frit and powdered copper and was then fired at 750.degree. C. in a nitrogen atmosphere, whereby external electrodes electrically connected to the internal electrodes were formed.

Next, a nickel plating solution composed of nickel sulfate, nickel chloride and boric acid was prepared, and nickel plating was performed on the external electrodes by the barrel plating method. Finally, a solder plating solution composed of an alkanol-sulfonic acid bath (AS bath) was prepared, and solder plating was performed on the nickel plating film described above, whereby a predetermined laminated ceramic capacitor was obtained.

The dimensions of the laminated ceramic capacitor thus obtained were such that the width was 3.2 mm, the length was 4.5 mm a