JPH0551127B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a dielectric ceramic composition suitable as a dielectric for a temperature-compensating multilayer ceramic capacitor whose internal electrodes are made of a base metal such as nickel. [Prior art] JP-A-59-227769 describes {(Sr _1-x Ca _x O} _k
A dielectric ceramic composition comprising a basic component consisting of TiO ₂ and an additive component consisting of Li ₂ O, SiO ₂ and MO (where MO is at least one metal oxide of BaO, CaO and SrO). Disclosed. Since this ceramic composition can be sintered in a non-oxidizing atmosphere, it can be used to provide a temperature-compensating multilayer ceramic capacitor whose internal electrodes are made of a base metal such as nickel. By the way, in order to improve the performance and reduce the size of temperature-compensating ceramic capacitors, a dielectric ceramic composition having a high Q and a high resistivity σ is required, and the dielectric ceramic composition disclosed in the above-mentioned publication is required. For materials, the temperature coefficient (TC) of dielectric constant is +350 ~
In the range of −1000 (ppm/°C), the Q is less than 4400, and a sufficient Q cannot necessarily be obtained _. A basic component consisting of _xy Ca _x M _y ) O _k ) (Ti _1-z Zr _z ) O ₂ (where M is Mg or Zn),
Li ₂ O and SiO ₂ and MO (BaO, MgO, ZnO, SrO and
Disclosed is a new dielectric ceramic composition comprising an additive component consisting of at least one type of CaO. This new dielectric porcelain composition has a temperature coefficient (TC) of 1.0×10 ⁷ M at 20°C with a Q of more than 4500 within and outside the range of +350 to -1000 (ppm/°C).
It is possible to obtain a resistivity ρ of Ω·cm or more. [Problems to be Solved by the Invention] The dielectric ceramic composition disclosed in the above specification is sufficient as a dielectric substrate for capacitors used under normal environmental conditions (for example, -25°C to +85°C). Usable, but under harsh environmental conditions (e.g. 125
It was found that this material is not sufficient as a dielectric substrate for capacitors that may be used at temperatures (°C). In other words, with the dielectric ceramic composition disclosed in the above specification, it is impossible to increase the resistivity ρ to 1.0×10 ⁵ MΩ·cm or higher at high temperatures (for example, 125° C.) while maintaining Q at 5000 or higher. or difficult. Therefore, the object of the present invention is to use a non-oxidizing atmosphere, 1200
It can be obtained by firing at temperatures below ℃, and Q
is 5000 or more, resistivity ρ at 125℃ is 1.0×
The object of the present invention is to provide a dielectric ceramic composition having a resistance of 10 ⁵ MΩ·cm or more. [Means for Solving the Problems] The present invention for solving the above problems and achieving the above objects consists of 100 parts by weight of the basic components and 0.2 to 15.0 parts by weight of the basic components.
parts by weight of additional ingredients, and the basic ingredients are:
{(Ma _1-yz Mb _y ) Mn _z O} _k (Ti _1-W Zr _W ) O ₂ (However,
Ma is at least one metal of Sr (strontium) and Ca (calcium), Mb is at least one metal of Mg (magnesium) and Zn (zinc), y, z, k, w are , 0.005≦y≦0.100,
0.001≦z≦0.100, 1.00≦k≦1.200, 0.005≦w≦
0.100), and the additive component is
40-80 mol% _SiO2 and 20-60 mol% MO (however,
MO relates to a dielectric ceramic composition characterized in that it consists of at least one metal oxide of BaO, MgO, ZnO, SrO, and CaO. [Operations and Effects of the Invention] The dielectric ceramic composition of the invention described above can be obtained by firing in a non-oxidizing atmosphere at 1200°C or lower, so it can be used as a dielectric for temperature-compensating multilayer ceramic capacitors whose internal electrodes are made of base metals such as nickel. It is suitable. According to this dielectric ceramic composition, the relative permittivity ε _s is 150
~323, Q is 5000 or more, temperature coefficient TC of permittivity is −
600 to -3100ppm/℃, resistivity ρ is 1.0× at 20℃
It is possible to obtain a temperature-compensating ceramic capacitor with a resistance of 10 ⁷ MΩ·cm or more and a value of 1.0×10 ⁵ MΩ·cm or more at 125°C. The major difference between the dielectric ceramic composition disclosed in the above-mentioned Japanese Patent Application No. 60-289003 and the dielectric ceramic composition of the present invention is that the resistivity ρ at 125°C is maintained while maintaining a Q of 5000 or more. is 1.0×10 ⁵ MΩ・cm or more. The reason why it is possible to suppress the decrease in resistivity ρ at high temperatures while maintaining such a high Q is because Si (manganese) is included as a basic component. As the amount of manganese in the basic component increases, the resistivity ρ at high temperatures increases, but if it increases too much, Q decreases and desired characteristics cannot be obtained. By using the dielectric ceramic composition according to the present invention which has a large resistivity ρ at high temperatures, the distance between the electrodes of the capacitor can be shortened, so that the temperature compensating ceramic capacitor used under high temperature conditions can be miniaturized. be able to. Further, since it is possible to provide a ceramic capacitor having a high Q despite the large resistivity ρ, it is possible to improve the performance of electronic circuits using the ceramic capacitor. [Example] Next, Examples (including comparative examples) of the present invention will be described. k=1.00, x= of sample No. 1 in Table 1
0.28, y = 0.01, _{z = 0.02 , w = 0.01 . 0.28} , Mb _0.01
= Zn _0.01 , so in order to obtain the basic component consisting of (Sr _0.69 Ca _0.28 Zn _0.01 Mn _0.02 ) O) Ti _0.95 Zr _0.05 ) O ₂ , SrCO ₃ (strontium carbonate), CaCO ₃ (carbonate Calcium), ZnO (zinc oxide), MnO (manganese oxide), TiO ₂ (titanium oxide), nZrO ₂ (zirconium oxide) are prepared as starting materials, and without adding impurities,

[Table] were weighed, 2.5 parts of water was added to these raw materials, and wet-mixed for 15 hours. Next, this raw material mixture was dried at 150°C for 4 hours,
It was then crushed. Next, this pulverized material was heated to 1100°C.
Then, the powder was calcined in the air for 2 hours to obtain a powder having the basic components of the above composition formula. On the other hand, in order to obtain the additive components of sample No. 1 in Table 2,

【table】

[Table] was weighed, 300 c.c. of alcohol was added to it, stirred for 10 hours using an alumina ball in a polyethylene pot, and then pre-calcined in the air at 1000℃ for 2 hours.
Put this in an alumina pot with 300 c.c. of water,
Grind in an alumina ball for 15 hours, then 150
Dry at ℃ for 4 hours to obtain 80 mol% _SiO2 and 20 mol% MO.
A powder of additive components having a composition of (BaO 4 mol % + MgO 4 mol % + ZnO 4 mol % + SrO 4 mol % + CaO 4 mol %) in mol % was obtained. Next, 30 g (3 parts by weight) of the above additive component powder was added to 1000 g (100 parts by weight) of the basic component powder, and an organic binder consisting of an aqueous solution of acrylic acid ester polymer, glycerin, and condensed phosphate was added. Based on the combined weight of basic ingredients and added ingredients
15% by weight was added, and further 50% by weight of water was added, and these were placed in a ball mill and ground and mixed to prepare a slurry of porcelain raw materials. Then, the above slurry is put into a vacuum deaerator to degas it, this slurry is put into a reverse roll coater, which is used to form a thin film based on the slurry on a polyester film, and this thin film is then put on a film. Heat it to 100℃ and dry it to a thickness of about 25μ.
A green sheet (unsintered porcelain sheet) of m was obtained. This sheet is long, but
Use by punching out 10cm squares. On the other hand, the conductive paste for internal electrodes has an average particle size of
10g of 1.5μm nickel powder and ethylcellulose
It was obtained by putting 0.9 g dissolved in 9.1 g of butyl carbitol into a stirrer and stirring for 10 hours. This conductive paste was printed on one side of the green sheet through a screen having 50 patterns of 14 mm in length and 7 mm in width, and then dried. Next, two green sheets were laminated with the printed side facing up. At this time, the adjacent upper and lower sheets were arranged so that their printed surfaces were shifted by about half in the longitudinal direction of the pattern. Further, four green sheets each having a thickness of 60 μm were laminated on the upper and lower surfaces of this laminate. This lamination is then heated to approximately 50°C.
40 tons of pressure was applied in the thickness direction at a temperature of . Thereafter, this laminate was cut into a grid shape to obtain approximately 50 laminate chips. Next, this laminate chip was placed in a furnace capable of atmospheric firing, and fired at a rate of 100°C/h for 600°C in an atmospheric atmosphere.
The organic binder was burned by increasing the temperature to ℃. After that, the atmosphere of the furnace is changed from the atmosphere to H ₂ 2% by volume +
The atmosphere was changed to 98% by volume of _N2 . Then, while maintaining the furnace in a reducing atmosphere as described above, the heating temperature of the stacked chips was increased from 600°C to 1190°C, the sintering temperature.
℃ at a rate of 100℃/h, held at 1190℃ (maximum speed) for 3 hours, and then heated to 600℃ at a rate of 100℃/h.
The temperature was raised to .degree. C., the atmosphere was changed to an air atmosphere (oxidizing atmosphere), and oxidation treatment was performed by holding the temperature at 600.degree. C. for 30 minutes, followed by cooling to room temperature to obtain sintered chips. Next, a conductive paste consisting of zinc, glass frit, and vehicle is applied to the side surface of the fired chip where the electrodes are exposed, and dried.
Baking for 15 minutes at a temperature of °C to form a zinc electrode layer;
Furthermore, copper was deposited on this by electroless plating, and a Ph-Sn solder layer was further provided on this by electroplating to form a pair of external electrodes. As a result, as shown in the drawing, the dielectric ceramic layers 1, 2, 3, internal electrodes 4, 5, external electrodes 6,
A multilayer ceramic capacitor 10 consisting of 7 was obtained.
Note that the thickness of the dielectric ceramic layer 2 of this capacitor 10 is 0.02 mm, and the opposing area of the internal electrodes 4 and 5 is 5 mm.
×5mm= ^25mm2 . In addition, the porcelain layer 1 after sintering,
The compositions of Nos. 2 and 3 are practically the same as the mixed composition of the basic components and additive components before sintering, and are the basic components (Sr _0.69 Ca _0.28 Zn _0.01 Mn _0.02 )O of the composite perovskite type structure. ) Ti _0.95 Zr _0.05 ) SiO ₂ 80 mol% and BaO 4 mol% between the crystal grains of O ₂
A uniform distribution of additive components consisting of 4 mol % MgO, 4 mol % ZnO and 4 mol % SrO is obtained. Next, we measured the dielectric constant ε _s , temperature coefficient TC, Q, and resistivity ρ of the completed multilayer ceramic capacitor, and as shown in Sample No. 1 in Table 3, ε _s was 279, and TC was -1400 ppm/ ℃, Q is 8800, ρ is 3.2× at 20℃
10 ⁷ MΩ・cm, and 1.9×10 ⁵ MΩ・cm at 125°C. Note that the above electrical characteristics were measured using the following capacity. (A) The relative permittivity ε _s is calculated by measuring the capacitance at a temperature of 20°C, a frequency of 1 MHz, and an AC voltage (effective value) of 0.5 V, and using this measured value and the thickness of the ceramic layer 2 of 0.05 mm. I asked for it. (B) Temperature coefficient (TC) is the capacitance at 85°C (C ₈₅ )
and the capacitance (C ₂₀ ) at 20° C. were measured and calculated as C ₈₅ −C ₂₀ /C ₂₀ ×1/65×10 ⁶ (ppm/° C.). (C) Q was measured with a Q meter at a temperature of 20° C., a frequency of 1 MHz, and a voltage [actual value] of 0.5 V AC. (D) Resistivity ρ (MΩ・cm) at temperatures of 20℃ and 125℃
After applying DC50V for 1 minute each, the resistance value between the pair of external electrodes 6 and 7 was measured,
It was calculated based on the dimensions of this measured value. The preparation method and characteristics of sample No. 1 have been described above, but the other samples No. 2 to 78 have also been described.
Sample No. 1 was used, except that the composition of the basic components and additive components, their proportions, and the firing temperature in a reducing atmosphere (non-oxidizing atmosphere) were changed as shown in Tables 1, 2, and 3. A multilayer ceramic capacitor was produced in exactly the same manner as in Example 1, and its electrical properties were measured in the same manner. _Table 1 shows _{the numerical values} k, x _{, y ,} z, w, that is, numerical values indicating the ratio of the number of atoms of each element, and the content of Mb are shown. Table 2 shows the amount (parts by weight) of the additive components relative to 100 parts by weight of the basic component of each sample and the composition of the additive components. In the MO content column of Table 2, the proportions of BaO, MgO, ZnO, SrO, and CaO are shown in mol%. Table 3 shows the firing temperature (maximum temperature) for sintering in a reducing atmosphere and the electrical properties of each sample.

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

[Table] As is clear from Tables 1 to 3, in the samples according to the present invention, when fired in a non-oxidizing atmosphere at 1200°C or lower, the dielectric constant ε _S is 151 to 323, the Q is 5000 or more, and the dielectric constant The temperature coefficient TC ranges from -690 to -3400ppm/℃. Also, the resistivity ρ is 1.0×10 ⁷ MΩ・at 20℃
cm or more, and 1.0×10 ⁵ MΩ・cm or more at 125℃. On the other hand, sample No. 14, 15, 16, 17, 18, 24, 28,
29, 33, 38, 43, 44, 48, 49, 53, 58, 59, 64,
65, 71, 72, and 78 cannot achieve the object of the present invention. Therefore, these are outside the scope of the present invention. Next, the reasons for limiting the composition will be described. When the amount of additive components added is zero, as shown in sample No. 72, a dense sintered body cannot be obtained even if the firing temperature is 1300℃, but as shown in sample No. 73, when the amount added is 100 If the amount is 0.2 part by weight based on the weight part of the basic component, a sintered body having desired electrical properties can be obtained by firing at 1190°C. Therefore, the lower limit of added ingredients is 0.2
Parts by weight. On the other hand, when the amount added is 18 parts by weight as shown in sample No. 78, Q becomes less than 5000, which is worse than the desired properties, but when the amount added is 15 parts by weight as shown in sample No. 77, , desired characteristics can be obtained. Therefore, the upper limit of the amount added is 15 parts by weight. As shown in Sample Nos. 19, 20, 21, 22, and 23, for example, the value of x can be any value from 0 to 0.994 to obtain desired electrical characteristics. Therefore, the value of x includes all values from 0 to 0.994.
In addition, when x is 0.994 as shown in sample No. 23,
x+y+z=1, and Sr is zero after all. Therefore, the content of Ma in the general formula according to the present invention is Sr,
It is either Ca or Sa+Ca. When the value of y is 0.002 as shown in sample Nos. 24 and 29, no effect of adding Mb (Mg and/or Zn) is seen, but when the value of y is 0.002 as shown in samples Nos. 25, 30, and 34,
In the case of 0.005, desired electrical characteristics are obtained.
Therefore, the lower limit of the value of y is 0.005. On the other hand, when the value of y is 0.12 as shown in sample Nos. 28, 33, and 38, a dense sintered body cannot be obtained;
As shown, desired electrical characteristics can be obtained when the value of y is 0.10. Therefore, the upper limit of the value of y is 0.10. When the value of z is 0.0005 as shown in sample Nos. 44 and 49, ρ at 125°C falls below 1.0×10 ⁵ MΩ・cm, and no effect of MnO addition can be seen.
As shown in Nos. 39, 45, and 54, desired electrical characteristics can be obtained when the value of z is 0.001. Therefore, the lower limit of z is 0.001. On the other hand, when the value of z is 0.12, as shown in sample Nos. 43, 48, 53, and 58, Q will be less than 5000 even if ρ is a satisfactory value; , 52, 57, the value of z is
In the case of 0.10z, desired electrical characteristics can be obtained.
Therefore, the upper limit of the value of z is 0.10. For example, as shown in sample Nos. 50, 51, and 52, when the value of z is gradually increased, ρ at 125°C also gradually increases, indicating that Mn contributes to the increase in resistivity ρ at high temperatures. I understand. When the value of w is 0.002 as shown in sample No. 59,
Although ρ at 125°C is less than 1.0×10 ⁵ and the effect of adding ZrO ₂ cannot be seen, when the value of w is 0.005 as shown in sample No. 60, the desired electrical characteristics can be obtained. It will be done. Therefore, the lower limit of the value of w is 0.005.
On the other hand, when the value of w is 0.12 as shown in sample No. 64, a dense sintered body cannot be obtained, but when the value of w is 0.10 as shown in sample No. 63, the desired electrical properties can be obtained. is obtained. Therefore, the upper limit of the value of w is 0.10. When the value of k is 0.99 as shown in sample No. 65,
ρ is 3.8×10 ³ and 1.0×10 ¹ M at 20℃ and 125℃, respectively.
Ω·cm, and Q is also significantly lowered to 50, but as shown in sample No. 66, when the value of k is 1.00, the desired electrical characteristics can be obtained. Therefore, the lower limit of the value of k is
It is 1.00. On the other hand, the value of k is as shown in sample No. 71.
When the value of k is 1.25, a dense sintered body cannot be obtained, but when the value of k is 1.20, as shown in sample No. 70, the desired electrical characteristics can be obtained. Therefore, the upper limit of the value of k is
It is 1.20. Preferred compositions of additive components are sample Nos. 1, 2, 3,
As is clear from mag. 9, SiO ₂ −MO (however, MO is
At least one metal oxide among BaO, MbO, ZnO, SrO and CaO) SiO ₂ in a binary system
The composition is within the range of 40 to 80 mol% and 20 to 60 mol% of MO. If the composition is within this range, desired electrical characteristics can be obtained. On the other hand, if the composition of the additive components falls outside the range specified in the present invention, as in Sample Nos. 14, 15, 16, 17, and 18, a dense sintered body cannot be obtained. [Modifications] Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and, for example, the following modifications are possible. (a) MnO, the starting material for obtaining the basic components
It is also possible to partially replace it with MnO ₂ or Mn ₃ O ₄ within a range that does not impede the object of the present invention. Further, other substances may be added to the basic components and additive components as necessary. (b) The starting materials for obtaining the basic components may be oxides or hydroxides such as SrO, CaO, etc. or other compounds other than those shown in the examples. Further, the starting materials for the additive components may be other compounds such as oxides and hydroxides. (c) The oxidation temperature may be set to a temperature other than 600°C lower than the sintering temperature (preferably 1000°C or less).
That is, various changes can be made in consideration of the electrodes made of nickel or the like and the oxidation of the porcelain. (d) The firing temperature in a non-oxidizing atmosphere can be varied depending on the electrode material. (e) Sintering may be performed in a neutral atmosphere. (f) It is of course applicable to general ceramic capacitors other than multilayer ceramic capacitors.

[Brief explanation of drawings]

The drawing is a sectional view showing a multilayer ceramic capacitor according to an embodiment of the present invention. 1, 2, 3... dielectric ceramic layer, 4, 5... internal electrode, 6, 7... external electrode.

Claims (1)

[Scope of Claims] 1 Consists of 100 parts by weight of a basic component and 0.2 to 15.0 parts by weight of additional components, wherein the basic component is {(Ma _1-yz Mb _y Mn _z )O} _k (Ti _{1- w} Zr _w )O ₂ (However, Ma is at least one metal among Sr and Ca, Mb is at least one metal among Mg and Zn, and y, z, k, and w are 0.005≦ y≦0.100,
0.001≦z≦0.100, 1.00≦k≦1.20, 0.005≦w≦
0.100), and the additive components include 40 to 80 mol% SiO2 and 20 to 80 mol _{% SiO2} .
60 mol% MO (however, MO is BaO, MgO, ZnO,
A dielectric ceramic composition comprising at least one metal oxide selected from SrO and CaO.