JP3361531B2 - Dielectric ceramic composition for Ni internal electrode - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric porcelain composition for Ni internal electrodes , and more particularly to a high dielectric constant, low dielectric loss, high voltage application at a high temperature. The present invention relates to a highly reliable dielectric ceramic composition having a good life (high temperature load life). 2. Description of the Related Art A multilayer ceramic capacitor widely used for an IC circuit element or the like used for an electronic device such as a communication device, an electronic computer, and a television receiver preferably has a small size and a large capacity. [0003] Multilayer ceramic capacitor having a large capacity such a small, for example such as BaTiO _3, can be produced by using a dielectric material mainly composed of titanium salt. Heretofore, methods for manufacturing a multilayer ceramic capacitor are roughly classified into a printing method and a sheet method. [0005] In the former method, after a dielectric slurry is prepared, it is printed in a predetermined shape by, for example, screen printing, dried, and then an electrode paste is printed thereon. Is repeated to laminate the dielectric layer and the internal electrode layer. In the latter case, a dielectric sheet is formed by, for example, a doctor blade method, an electrode paste is printed thereon, and a plurality of the sheets are stacked and thermocompression bonded. [0007] The laminated body is fired at a temperature of 1250 ° C to 1400 ° C in air to form a sintered body, and an external lead-out electrode, which is electrically connected to the internal electrode, is baked on the sintered body. I was getting a capacitor. In these methods, since the internal electrode layer serving as the electrode of the capacitor and the dielectric layer are simultaneously fired, the material of the internal electrode is that a metal electrode can be formed within the temperature at which the dielectric sinters. It is necessary that the material does not oxidize or react with the dielectric even when heated to the above temperature. For this reason, precious metals such as platinum, palladium and alloys thereof have been mainly used to satisfy these conditions. However, although these noble metals are very stable, they are expensive and their share in the cost of the multilayer ceramic capacitor is very large, about 20 to 50%, and the number of layers increases as the capacitance increases. Therefore, it was the biggest cause of the cost increase. To address this problem, Ni, Cu, F
Attempts have been made to use inexpensive base metals such as e-alloys as electrodes. However, when, for example, Ni is used as a base metal electrode material, Ni oxidizes when fired in air at the same time as the dielectric layer, and Ni diffuses into the dielectric layer. As a result, the metal electrode layer is not formed, and becomes insulated. For this reason, the function as an electrode cannot be performed. Therefore, in order to prevent the oxidation of Ni, firing is performed in a neutral or reducing atmosphere. In this case, however, the dielectric material is reduced and the specific resistance of the dielectric layer is very low. In particular, the service life for applying a voltage at a high temperature is shortened. Therefore, it has a problem that it cannot be used as a dielectric material for capacitors. Accordingly, an object of the present invention is to provide a laminated ceramic
As a dielectric material used for capacitors, a non-reducing not be reduced by firing in a neutral or reducing atmosphere to Ni and simultaneously and high dielectric constant, the dielectric loss is small,
An object of the present invention is to provide a dielectric porcelain composition having a high insulation resistance and a long life for applying a voltage at a high temperature. [0015] To achieve the above object Means for Solving the Problems] The present inventors as a result of intensive study, a dielectric ceramic composition composed mainly of barium titanate, the dielectric ceramic sets
Composition formula Narubutsu is _{{Ba (100-x) Ca} x} A · {Ti (100-y) Zr y} B
· Indicated by O ₃ + aMnO + bSiO ₂ + cY ₂ O ₃
In the composition , x, y, A, B, a, b, and c are each 0 ≤ x ≤ 24 (mol%) 8 ≤ y ≤ 22 (mol%) 1.000 ≤ A / B ≤ 1.040 0.05 ≤ a ≤ 1.0 0.05 ≤ b ≦ 1.0 0.05 ≦ c ≦ 1.0 (where a, b, and c are the above-mentioned ｛Ba _(100-x) Ca _x ｝ A ·
_{{Ti (100-y) Zr} y} dielectric ceramic composition in the range of percentages by weight) in terms of oxide with respect to B · O ₃ was found to solve the problems described above. EXAMPLES As starting materials, BaCO ₃ , TiO ₂ , Z
rO ₂ , CaCO ₃ , MnO or Cr ₂ O ₃ , SiO
₂ and Y ₂ O ₅ are weighed and mixed such that the compositions after firing are as shown in Tables 1 and 2, respectively. After that, it is dehydrated and dried at 1050 ° C. to 1240
Temporarily bake at 2 ° C. for 2 hours. The calcined body is finely pulverized, dehydrated and dried to obtain a powder. An appropriate amount of an organic binder is added to the obtained powder to obtain a sheet having a thickness of 20 μm and a thickness of 100 μm. Next, first, on both sides of a sheet having a thickness of 20 μm,
An electrode paste in which Ni powder is dispersed in a vehicle is applied by screen printing to form an electrode. Further, a sheet having a thickness of 100 μm is pressed on both upper and lower surfaces by thermocompression.
The sheet having a thickness of 100 μm is provided to increase the strength of the element body in consideration of handling after firing, and does not affect the electrical characteristics at all. [0020] The thermocompression bonding sheets cut to dimensions of 3.9 × 1.9 mm it put on zirconia plate, to burn an organic binder was heated in air up to put 500 ° C. in a sagger, then N ₂ 1300 ° C to 1 in water or N ₂ + H ₂
Bake at 400 ° C. for 2 hours. The size of the green body after firing is about 3.2 × 1.6 mm. After that, 800 ° C. to 1100 in air + N ₂
Anneal at 2 ° C for 2 hours to obtain a sample. In-Ga was applied to the end of the sample, and its electrical characteristics were measured as an external lead electrode. Electrical characteristics include relative permittivity (ε), dielectric loss (tan δ,%), insulation resistance (IR, Ω, 25 VD
C, 60 seconds value), high temperature load life (100VD at 200 ° C)
Time HR until C is applied and a current of 6 mA or more flows.
Is measured. The results are shown in Tables 1 and 2. In Tables 1 and 2, those marked with * are out of the scope of the present invention and are presented for comparison with those of Examples of the present invention. [Table 1] [Table 2] As is clear from Tables 1 and 2, the material of the present invention has a particularly high relative dielectric constant of 7000 or more, and the tan δ is
It shows a small value of 0.8% to 4.8%, and has a long load life at a high temperature of 50 hours to 185 hours. Further, the insulation resistance IR at room temperature also shows a high value. Next, the reason for limiting the numerical value of each tissue range according to the present invention will be described. First, when x is larger than 24, the relative dielectric constant εs decreases, and the high-temperature load life also becomes very short (for example, see Sample No. 21 in Table 2). When y is smaller than 8, the relative permittivity εs decreases and the dielectric loss tan δ also increases (for example, see Table 2).
Sample No. 29). When y exceeds 22, the relative dielectric constant εs
(See, for example, Sample No. 25 in Table 2). When A / B is smaller than 1.000, the dielectric material is reduced, the insulation resistance IR is reduced, and the high temperature load life is shortened (for example, see Sample No. 16 in Table 1). When A / B is larger than 1.040, sintering becomes insufficient, the relative dielectric constant εs decreases, the dielectric loss tanδ increases, the insulation resistance IR decreases, and the high-temperature load life decreases (for example, sample No. 2 in Table 2). 20). Further, when a is smaller than 0.05, the dielectric loss tan δ is large and the high-temperature load life is short (for example, see Sample No. 6 in Table 1). When a is larger than 1.0, the relative dielectric constant εs
And the high-temperature load life is shortened (for example, see Sample No. 10 in Table 1). When b is smaller than 0.05, the relative dielectric constant εs
And the high temperature load life is shortened (for example, the sample in Table 1)
No. 1). When b exceeds 1.0, the relative dielectric constant εs
And the high-temperature load life is shortened (for example, see Sample No. 5 in Table 1). When c is smaller than 0.05, the high temperature load life is shortened (for example, see Sample No. 11 in Table 1). When c exceeds 1.0, the dielectric material is reduced, the insulation resistance IR is reduced, and the high-temperature load life is shortened (for example, see Sample No. 15 in Table 1). In summary, by selecting a, b, and c as described above, the high temperature load life can be improved. If x is more than the above value, the relative permittivity εs decreases. If y is less than the above value, the Curie point is on the high temperature side, and the relative permittivity εs at room temperature decreases. The loss tan δ is also large. If y is more than the above value, the Curie point moves to the low temperature side, so that the relative dielectric constant εs decreases. When A / B is less than 1.000, that is, when Tirich is reached, reduction becomes weak, resulting in a decrease in insulation resistance IR. When A / B is more than 1.040, sintering becomes insufficient. According to the present invention, even when fired in a neutral or reducing atmosphere, the dielectric constant is high, the dielectric loss is small, the high temperature load life is long, and the insulation resistance is high and the reliability is high. Sexual N
i A dielectric ceramic composition for an internal electrode can be obtained. As a result, a multilayer ceramic capacitor using Ni as an internal electrode can be manufactured.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hitoshi Masumura               1-13-1 Nihonbashi, Chuo-ku, Tokyo               IDK Corporation                (56) References JP-A-2-106681 (JP, A)

Claims (1)

(57) [Claims] [Claim 1] A dielectric mainly composed of barium titanate
Consists ceramic composition, the composition formula of the dielectric ceramic composition _{{Ba (100-x) Ca} x} A · {Ti (100-y) Zr y} B
· Indicated by O ₃ + aMnO + bSiO ₂ + cY ₂ O ₃
In the composition , x, y, A, B, a, b, and c are 0 ≦ x ≦ 24 (mol%) 8 ≦ y ≦ 22 (mol%) 1.000 ≦ A / B ≦ 1.040 0.05 ≦ a ≦ 1.0 0.05 ≦ b ≦ 1.0 0.05 ≦ c ≦ 1.0 (where a, b, and c are the above-mentioned ｛Ba _(100-x) Ca _x ｝ A ·
_{{Ti (100-y) Zr} y} B · O 3 Ni in, characterized in that it has a range of percentages by weight) in terms of oxide with respect to
Dielectric ceramic composition for external electrodes .