JPS6224388B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field The present invention relates to a dielectric ceramic composition suitable for temperature-compensating multilayer ceramic capacitors with internal electrodes made of base metals, and more specifically, the present invention relates to a dielectric ceramic composition suitable for temperature-compensating multilayer ceramic capacitors with internal electrodes made of base metals. The present invention relates to a dielectric ceramic composition obtained by heat-treating the composition in an oxidizing atmosphere at a temperature lower than the sintering temperature. Conventional technology Conventionally, when manufacturing multilayer ceramic capacitors,
A conductive paste of a noble metal such as platinum or palladium was printed on a dielectric green sheet (green sheet), a plurality of sheets were stacked and pressed together, and the sheets were fired at a high temperature in an oxidizing atmosphere. By using precious metals in this way,
The desired internal electrode can be obtained even by high-temperature firing in an oxidizing atmosphere. However, since precious metals such as platinum and palladium are expensive, the cost of multilayer ceramic capacitors has inevitably increased. In order to solve this type of problem, it is conceivable to apply a conductive paste containing a base metal such as nickel as a main component to a raw sheet and sinter it in a reducing or neutral atmosphere (non-oxidizing atmosphere). but,
Even when sintering is performed in a non-oxidizing atmosphere, if the sintering temperature exceeds 1300°C, base metals such as nickel will melt and agglomerate, making it difficult to obtain high-quality internal electrodes. Purpose of the Invention Therefore, the purpose of the present invention is to enable sintering at a relatively low temperature (below 1200°C) in a non-oxidizing atmosphere, have a dielectric constant of 100 or more, and have a Q
The object of the present invention is to provide a dielectric ceramic composition capable of obtaining characteristics of 1000 or more and a resistivity of 10 ⁶ MΩ·cm or more. Structure of the Invention The present invention to achieve the above object is as follows:
{(Sr _(1-x) Ca _x )O} _k TiO ₂ (However, x, k are 1.0
≧x≧0, 1.04≧k≧1.00) and 0.2 to 10.0 parts by weight of a glass component, the glass component being
It consists of Li ₂ O, M (where M is at least one metal oxide of BaO, CaO, and SrO), and SiO ₂ , and the composition range of the Li ₂ O, the M, and the SiO ₂ is as follows. In the triangular diagram showing the composition in mol%, the Li ₂ O is 0 mol%, the M is 35 mol%,
A first point A having a composition of 65 mol% of SiO ₂
and the Li ₂ O is 0 mol%, the M is 40 mol%,
A second point B where the SiO ₂ has a composition of 60 mol%
and the Li ₂ O is 5 mol%, the M is 45 mol%,
A third point C having a composition of 50 mol% of SiO ₂
and the Li ₂ O is 50 mol%, the M is 0 mol%,
A fourth point D having a composition of 50 mol% of SiO ₂
and the Li ₂ O is 25 mol%, the M is 0 mol%,
A fifth point E where the SiO ₂ has a composition of 75 mol%
The present invention relates to a dielectric ceramic composition characterized in that the area is within an area surrounded by five straight lines sequentially connecting the first point A and the first point A. The basic components related to the present invention are (MeO) _k TiO ₂ (however,
Me is a metal selected from Sr, Ca and Sr+Ca, k
can also be expressed as 1.00-1.04). Effects of the invention According to the above invention, in a non-oxidizing atmosphere,
By sintering at a temperature of 1200°C or less and heat-treating in an oxidizing atmosphere at a temperature of 1000°C or less, preferably 600 to 1000°C, the dielectric constant is 100 to 100°C.
300, a dielectric ceramic composition having a Q of 1000 or more and a resistivity of 10 ⁶ MΩ·cm or more can be obtained. Therefore,
It is possible to provide a temperature-compensating multilayer ceramic capacitor whose internal electrode is made of a base metal such as nickel. Examples Next, Examples 1 to 83 related to the present invention will be described. However, in order to clarify the present invention, examples outside the scope of the present invention are also included. In Example 1, {(Sr _(1-x) Ca _x )O} _k 1 in the composition formula of TiO ₂
In order to obtain the basic components where -x is 0.62, x is 0.38, and k is 1.0, that is, {(Sr ₀ . ₆₂ Ca ₀ . ₃₈ ) O} ₁ .0 TiO ₂ , SrCO ₃ , CaCO ₃ with a purity of ₉₉ % or more, and TiO ₂ were prepared as starting materials, and these were weighed so that the proportions were 0.62 mol part of SrCO ₃ , 0.32 mol part of CaCO ₃ , and 1.0 mol part of TiO ₂ . It was weighed without including impurities. Next, this raw material was wet mixed for 15 hours, pulverized, dried, and pre-calcined for 2 hours in the atmosphere at about 1200°C. As a result, the basic component of a composite perovskite crystal having the structure of {(Sr _(1-x) Ca _x )O} _k TiO ₂ is obtained. Next, 3 parts by weight of glass powder (glass component) having an average particle size of about 5 μm was added to 100 parts by weight of this calcined material (basic component). The glass component was 35 mol% as shown in the column of Example 1 in Table 1.
M (BaO14 mol%, CaO10.5 mol%, SrO10.5
mol %) and 65 mol % SiO ₂ . Furthermore, based on the total weight of the basic component and glass component,
Add an aqueous solution of an acrylic acid ester polymer, glycerin, and condensed phosphate as an organic binder to a concentration of 15% by weight, then add 50% by weight of water, grind and mix in a ball mill to form a slurry, and after defoaming treatment. A long green sheet was prepared using the doctor blade method. Next, after drying this green sheet, three green sheets 1, 2, and 3 were produced as shown in FIG. 1 by punching with a press. Next, a conductive paste containing Ni as a main component (91% by weight Ni , MnO1 wt%, PbO―BaO― _SiO2
Conductive paste layers 4 and 5 are formed by applying a paste consisting of 8% glass and vehicle to a thickness of approximately 3 μm.
The two green sheets 1 and 2 coated with conductive paste are formed so that the sides coated with conductive paste to the ends face in opposite directions, and conductive paste layers 4 and 5 are formed.
Stack them so that they are facing each other with one raw sheet in between,
Furthermore, green sheets 3 without applying conductive paste were stacked and thermocompression bonded to create an integrated laminate. Next, this laminate was placed in a heating furnace and heated to 600°C at a temperature increase rate of 100°C/h in an atmospheric atmosphere.
Hydrogen (H ₂ ) 1% by volume and nitrogen (N ₂ ) shown in Table 2
Furthermore, switch to a non-oxidizing atmosphere consisting of 99% by volume.
Sintering temperatures shown in Table 2 at a temperature rise rate of 100°C/h
After raising the temperature to 1110℃ and maintaining this 1110℃ for 3 hours, the temperature was lowered to 600℃ at a cooling rate of 100℃/h, and the non-oxidizing atmosphere was changed to an air atmosphere, and the temperature was increased to 600℃ for 30 minutes.
Hold for 1 minute to perform oxidation treatment, then leave in air
A laminated sintered body was produced by cooling to room temperature (approximately 20°C) at a cooling rate of 100°C/h. As a result, as shown in FIG.
Dielectric ceramic layers 1a, 2a, 3a corresponding to 2 and 3
and internal electrodes 4a corresponding to the paste layers 4 and 5,
A sintered body 6 consisting of 5a was obtained. Porcelain layer 1
The thickness of a, 2a, and 3a is approximately 0.05 mm, the thickness of the sintered body 6 including the electrode is approximately 0.16 mm, its vertical width and horizontal width are each 6 mm, and the opposing area of electrodes 4a and 5a is 5 mm x 5 mm.
mm= ^25mm2 . Also, the ceramic layers 1a, 2a, 3a
is composed of a porcelain composition in which a glass component is mixed into a composite provskite type porcelain crystal represented by the compositional formula of {(Sr _(1-x) Ca _x )O} _k TiO ₂ . Next, a conductive paste consisting of Zn (zinc), glass frit, and vehicle is applied to the side surface of the sintered body 6 where the electrodes 4a and 5a are exposed, and dried. By baking, a Zn electrode layer 7 is formed as shown in FIG. 4, and then copper is deposited on this layer by electroless plating to form a Cu layer 8. Further, a solder layer 9 is formed on this layer by electroplating. A pair of external electrodes 10 and 11 were formed. Next, the dielectric constant ε, Q, resistivity ρ, and temperature coefficient TC of the completed multilayer ceramic capacitor were measured, and the results shown in Table 2 were obtained. The electrical characteristics were measured under the following conditions. (A) The relative permittivity ε is at a frequency of 1k at a temperature of 20°C.
Hz, voltage [effective value] 0.5V AC, measure the capacitance with a Q meter, and compare this measured value with the electrode 4a,
It was calculated from the facing area of electrodes 5a of 25 mm ² and the thickness of ceramic layer 2a between electrodes 5a and 6a of 0.05 mm. (B) Q was measured using a Q meter under the same conditions as ε. (C) Resistivity ρ (MΩ・cm) at a temperature of 20℃
After applying DC50V for 1 minute, electrodes 10 and 11
The resistance value between them was measured and calculated based on this measured value and the dimensions. (D) Temperature coefficient TC is determined by measuring capacitance C ₈₅ at 85°C and capacitance C ₂₀ at 20°C, and calculating C ₈₅ - C ₂₀ /C ₂₀ ×1
/65×10 ⁶ (PPM/°C). Above, Example 1 has been described, but Examples 2-
Regarding No. 83, a multilayer ceramic capacitor was manufactured under exactly the same conditions as in Example 1, except that the ceramic composition and/or sintering conditions were changed as shown in Tables 1 and 2, and the electrical characteristics were determined using the same method. was measured. In addition, in the column of basic components in Table 1, the values of 1-x, x, and k in the compositional formula of {(Sr _(1-x) Ca _x )O} _k TiO ₂ are shown. Since the amount of the basic component is constant at 100 parts by weight in all Examples, it is not listed in the column of each Example. The amount of glass component is based on 100 parts by weight of the base component. In addition, in the H 2 ratio column of the sintering conditions in Table 2, the H ₂ ratio in the volume ratio of H ₂ and N ₂ in a non-oxidizing atmosphere during sintering _is shown.
(Hydrogen) volume % is shown. In addition, the sintering condition temperature column shows the sintering temperature in a non-oxidizing atmosphere. The heat treatment temperature in an oxidizing atmosphere (air) is 600° C. in each example, so it is not shown in the table. The mark 〃 in Tables 1 and 2 indicates the same as above.

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[Table] In Tables 1 and 2 above, Examples 6 to
10, 41, 47, 48, 51, 52, 55, 56, 59, 68, 71,
72, 75, 76, 79, 80 and 83 are outside the scope of the present invention, and the others are within the scope of the present invention. Further, in the examples in which the characteristics were not entered in the electrical characteristics column of Table 2, a dense sintered body could not be obtained. In Examples 1 to 40, the relationship between the composition of the glass component and the electrical characteristics of the ceramic capacitor was mainly determined in order to determine the composition of the glass component. As is clear from Examples 1 and 2, even if there is no Li ₂ O in the glass component, if the M component is 35 to 40 mol% in total and the remainder is SiO ₂ , the temperature is 1110°C.
sintered, ε is 290 or 291, Q is 4200 or
4000, a good capacitor with ρ of 5.8 or 5.9×10 ⁶ (MΩ·cm) can be obtained. As in Example 8, M
At 50 mol%, a dense sintered body cannot be obtained and the object of the present invention cannot be achieved. When Li ₂ O is 5 mol %, the M component is 45 mol % and SiO ₂ is 50 mol % as shown in Example 3, the same sintering temperature and electrical properties as in Examples 1 and 2 can be obtained. is 20 mol%, SiO ₂ is 80
When using mol%, the sintering temperature is high as shown in Example 7, and at 1250°C, a dense sintered body cannot be obtained and the object of the present invention cannot be achieved. In both Examples 9 and 10, SiO ₂ was 40 mol %, but in both Examples, a dense sintered body could not be obtained at 1250° C., and the object of the present invention was not achieved. As shown in Examples 4 and 5, even when no M component is included, Li ₂ O is 25 to 50 mol% and SiO ₂ is
If it is in the range of 50 to 75 mol %, electrical properties equivalent to those of Example 1 can be obtained and the object of the present invention can be achieved. As is clear from Examples 11 to 17, BaO, which constitutes the M component contained in the glass according to the present invention,
Regardless of whether CAO or SrO is used, or any combination thereof, it exhibits electrical characteristics equivalent to those of Example 1 and fully achieves the object of the present invention. Therefore, the composition range of the glass component in the present invention is determined by sequentially connecting points A, B, C, D, E, and A in FIG. 5, which shows the composition of Li ₂ O—M—SiO ₂ glass. This is within the area surrounded by five straight lines. In addition, in the triangular diagram shown in Fig. 5, point A indicates 0 mol% of Li ₂ O, 35 mol% of M, and 65 mol% of SiO ₂ , and point B indicates 0 mol% of Li ₂ O, 40 mol% of M, and 60 mol% of SiO ₂ . Point C indicates 5 mol% of Li _{2 O} , 45 mol% of M, and 50 mol% of SiO ₂ , Point D indicates 50 mol% of Li ₂ O, 0 mol% of M0, and 50 mol% of SiO ₂ , and Point E indicates Li ₂ It shows O25 mol%, M0 mol%, and _SiO2 75 mol%. Therefore, Examples 6 to 10 are outside the scope of the present invention. As shown in Examples 23 to 28, even if 1-x is 1.0, x is 0, and k is _{1.02, that is, (SrO) 1.02 TiO 2} , the glass component is within the range shown in Examples 1 to 5. If so, a dielectric ceramic composition (multilayer ceramic capacitor) with good electrical properties can be obtained. As shown in Examples 29 to 34, (1-x) is 0 and x is
1.0, k is 1.02, that is, (CaO) _{1.02 TiO2} , as long as the glass component is within the _range shown in Examples 1 to 5, a dielectric ceramic composition (laminated ceramic) with good electrical properties can be obtained. capacitor) is obtained. As shown in Examples 35 to 40, (1-x) is 0.3, x
Even if is 0.7 and k is 1.02, that is, (Sr ₀ . ₃ Ca ₀ . ₇ ) ₀ . ₀₂
The same applies to TiO ₂ as above. Examples 41 to 59 investigate the relationship between various porcelain compositions and the amount of glass component added. In each of the different groups of basic components of Examples 41-47, 48-51, 52-55, 56-59, the preferable addition amount of the glass component is 0.2 to 100 parts by weight of the basic components.
~10.0 parts by weight. When no glass component was added as in Examples 41, 48, 52, and 56, a dense sintered body was not obtained even though the firing temperature was as high as 1250°C, and the object of the present invention was not achieved. do not. Alternatively, as shown in Examples 47, 51, 55, and 59, when the amount of glass component added is 12 parts by weight, Q becomes less than 1000 and the object of the present invention is not achieved. Therefore, the amount of glass added is limited to a range of 0.2 to 10% by weight based on the basic components. In Examples 60 to 67, the relationship between firing atmosphere and characteristics was investigated. This shows that satisfactory electrical properties can be obtained in both neutral and reducing atmospheres with various porcelain compositions. However, in the case of a reducing atmosphere, the Q and specific resistance tend to be worse than in the case of firing in a neutral atmosphere, even if the composition is the same, but it is possible to sufficiently achieve the purpose of the present invention. This is a range. In Examples 68 to 83, changes in electrical characteristics with respect to changes in the value of k in the basic component were investigated. According to these examples, when the amount of Sr _(1-x) Ca _x O is small relative to the amount of Ti, such as when k is 0.98, the Q becomes poor and the resistivity ρ is also 6.2×10 ⁴ (MΩ ·cm)
As a result, the object of the present invention is not achieved. Also,
If the value of k is 1.05, a dense sintered body cannot be obtained and the object of the present invention cannot be achieved. Therefore, the value of k is limited to 1.0 to 1.04. As is clear from the above, according to the present invention, after firing at a temperature of 1070 to 1200°C in a reducing or neutral atmosphere, heat treatment at 600 to 1000°C in air results in a dielectric constant of 122 to 333 and a Q of 1400 to 1400. 7500, resistivity ρ is 5.1
It is possible to provide various dielectric ceramic compositions with TC of ×10 ⁶ to 3.2 × 10 ⁷ MΩ·cm. Furthermore, it is possible to provide a temperature-compensating multilayer ceramic capacitor in which the internal electrodes are made of a base metal such as nickel. Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be further modified. For example, the heat treatment temperature in an oxidizing atmosphere may be any temperature other than 600°C, such as 600 to 1000°C, that is, 200°C or more lower than the sintering temperature. This point can be considered by considering the temperature and time at which the porcelain is sufficiently oxidized while the electrode material is not oxidized. In addition, the composition of the present invention (which includes an anti-reducing range and includes a range that does not require oxidation treatment),
Although heat treatment is performed in an oxidizing atmosphere to increase the resistivity, this oxidation treatment can also be performed by baking the electrode paste (at 550 to 850°C) without performing it separately. Further, other substances may be further added within a range that does not impede the object of the present invention. For example, MnO ₂ may be added to the composition of the present invention in an amount of 0.05 to 0.1% by weight. In addition, the starting materials for obtaining the basic components may be other than those shown in the examples, such as Ca, Sr,
It may also be a Ti compound, for example an oxide such as CaO or SrO, or a hydroxide.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the raw sheets according to Examples 1 to 83, FIG. 2 is a perspective view showing the state in which nickel paste is printed on the raw sheet of FIG. 1, and FIG.
FIG. 4 is a cross-sectional view showing a product obtained by integrating and sintering the green sheets shown in the figure, and FIG. 4 is a cross-sectional view showing the sintered body of FIG. 3 provided with external electrodes. FIG. 5 is a triangular diagram showing the composition of glass components. 1, 2, 3... raw sheet, 1a, 2a, 3a... porcelain layer, 4, 5... paste layer, 4a, 5a... electrode,
6... Sintered body, 10, 11... External electrode.

Claims (1)

[Claims] 1 (MeO) _k TiO ₂ (Me is Sr, Ca and Sr+
100 parts by weight of a basic component consisting of a metal selected from Ca (k is 1.00 to 1.04), and a glass component of 0.2 to 10.0 parts by weight, the glass component being Li ₂ O and M (where M
In the triangular diagram showing the composition in mol% of at least one metal oxide of BaO, CaO and SrO) and SiO ₂ , the Li ₂ O is 0 mol%, the M is 35 mol%, the SiO a first point A having a composition of 65 mol% ₂ ;
The above Li ₂ O is 0 mol%, the above M is 40 mol%, the above
The second point B has a composition of 60 mol% SiO ₂ , the Li ₂ O is 5 mol%, the M is 45 mol%, and the
A third point C having a composition of 50 mol % of SiO ₂ , 50 mol % of said Li ₂ O, 0 mol % of said M;
A fourth point D having a composition of 50 mol % of SiO ₂ , 25 mol % of said Li ₂ O, 0 mol % of said M, and a fourth point D having a composition of 50 mol % of SiO 2
Dielectric porcelain, characterized in that it is within a region surrounded by five straight lines connecting in order the fifth point E having a composition of 75 mol % SiO ₂ and the first point A. Composition.