JP2952062B2 - Non-reducing dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-reducing dielectric ceramic composition, and more particularly, to a high dielectric constant, a small dielectric loss, and a good life to a voltage application at a high temperature (hereinafter referred to as a high temperature load life). And a highly reliable dielectric ceramic composition.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor widely used for an IC circuit element or the like used in electronic equipment such as a communication device, an electronic computer, and a television receiver preferably has a small size and a large capacity.

[0003] In the multilayer ceramic capacitor of large capacity such small, for example, is produced by the following method by using a dielectric material mainly composed of such titanate BaTiO _3.

Conventionally, methods for manufacturing a multilayer ceramic capacitor are roughly classified into a printing method and a sheet method.

In the former method, a dielectric slurry is prepared, then printed in a predetermined shape by, for example, screen printing, dried, and an electrode paste is printed thereon. After the electrode paste is dried, the next dielectric slurry is formed. By repeating the method of printing, a dielectric layer and an internal electrode layer are laminated.

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 laminate obtained by the appropriate method is fired in air at 1250 ° C to 1400 ° C to produce a sintered body, and an external lead electrode which is electrically connected to the internal electrode is baked on the sintered body. Was getting.

In these methods, since the internal electrode and the dielectric which are the electrodes of the capacitor are simultaneously fired, the material of the internal electrode is that the 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. For this reason, noble metals such as platinum and palladium have been mainly used to satisfy these conditions.

However, these precious metals are very stable, but are expensive, and the ratio of the cost of the multilayer ceramic capacitor to the cost is as large as about 20% to 50%, which is the biggest cause of the cost increase. Was.

In order to address this problem, Ni, Cu, F
Attempts have already been made to use inexpensive base metals such as e-alloys as internal electrodes.

[0011]

However, when, for example, Ni is used as the base metal electrode material, Ni oxidizes when fired simultaneously with the dielectric layer in air, and Ni diffuses into the dielectric layer. As a result, the metal electrode layer is not formed, and the insulating layer is formed. For this reason, the function as an electrode is not fulfilled.

Therefore, firing is performed in a neutral or reducing atmosphere to prevent oxidation of Ni. In this case, the dielectric material is reduced and the specific resistance of the dielectric layer is very low. And, in particular, the high temperature load life is shortened. Therefore, there is a problem that it cannot be used as a dielectric material for a capacitor.

Accordingly, an object of the present invention is to provide a dielectric material used for a multilayer ceramic capacitor which is non-reducing and not reduced even when fired in a neutral or reducing atmosphere simultaneously with a base metal such as Ni. The present invention provides a dielectric porcelain composition having a high dielectric loss, a low dielectric loss, a high insulation resistance, and a long high-temperature load life.

[0014]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and as a result, have made a polycrystalline solid solution containing barium titanate as a main component, and the composition formula of this solid solution is ｛Ba ( 1-x) Cax｝ A ・ ｛Ti (1-y) Zry｝ B ・ O ₃ + aM
₁ + bM ₂ + c (M ₃ + M ₄ ) In the composition represented by M ₁ , M ₂ , M ₃ , and M ₄ , at least one compound of M ₁ : Mn, Cr, M ₂ : Si compound, M ₃ : A compound of Y, a compound of M ₄ : W, and 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 (% by weight relative to ABO _{3 in} terms of oxide) 0.05 ≤ b ≤ 1.0 (% by weight relative to ABO _{3 in} terms of oxide) 0.05 ≤ c ≤ 2.0 (% in terms of oxide) ABO wt% relative to ₃₎ (provided that the maximum value of M ₃ is 1.0 wt%, the dielectric ceramic composition is a composition in the range of to.) the maximum value of M ₄ is 1.0% by weight the problem I found that solving the point.

[0015]

EXAMPLES As starting materials, BaCO ₃ , TiO ₂ , Z
rO ₂ , CaCO ₃ , MnO or Cr ₂ O ₃ , SiO
₂ , Y ₂ O ₃ , and WO ₃ are weighed and mixed such that the compositions after firing are as shown in Tables 1 and 2 below.

After that, it is dehydrated and dried, and 1050 ° C.-124
Temporarily bake at 0 ° C. for 2 hours. This 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, Ni was used on both sides of a sheet having a thickness of 20 μm for electrodes.
An electrode paste in which 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 the upper and lower sides by thermocompression. The sheet having a thickness of 100 μm is used to increase the strength of the element body in consideration of handling after firing, and does not affect the electrical characteristics at all.

The thermocompression-bonded sheet is cut to a size of about 3.9 × 1.9 mm, placed on a zirconia plate, placed in a sagger and heated to 500 ° C. in air to burn the organic binder. in N ₂ or N 1300 ° C. in ₂ + H ₂ in
Burn at １1400 ° C. for 2 hours.

The size of the green body after sintering is about 3.2 × 1.6 mm. Thereafter, annealing is performed at 800 ° C. to 1100 ° C. for 2 hours in air + N ₂ to obtain a sample.

The electrical characteristics are measured by coating In-Ga on the end of the sample and using it as an external extraction electrode. Electrical characteristics include relative permittivity (ε _s ), dielectric loss (t
anδ,%), insulation resistance (IR, Ω, 25VDC, 60
(Second value) and the high temperature load life (time until 200 mA or more and a current of 6 mA or more applied at 100 VDC, HR) are 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.

[0023]

[Table 1]

[0024]

[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, a small value of dielectric loss of 0.9 to 5.0%, and a high temperature load. The service life is as long as 100 to 640 hours. The insulation resistance at room temperature also shows a high value.

Next, the reasons for limiting the numerical values of the respective composition ranges of the present invention will be described.

[0027] First, when x is greater than 24, the relative dielectric constant epsilon _s is reduced (see, for example, sample No.26 in Table 2).

When y is smaller than 8, the relative dielectric constant ε
_s decreases, and the dielectric loss tan δ also increases (for example, see Sample No. 34 in Table 2). This is because the Curie point is on the high temperature side.

On the other hand, when y is greater than 22, the relative dielectric constant epsilon _s is reduced. This is because the Curie point moves to the low temperature side (for example, see Sample No. 30 in Table 2).

When A / B is less than 1000, the dielectric material is reduced, the insulation resistance IR is reduced, and it is impossible to measure the relative dielectric constant ε _s and the dielectric loss tan δ. Further, the high temperature load life is shortened (for example, see Sample No. 21 in Table 2).

Further, when A / B is larger than 1040, the relative permittivity ε _s decreases, and the dielectric loss tan δ also increases. The insulation resistance IR also decreases, and the high-temperature load life also decreases (see, for example, Sample No. 25 in Table 2).

When a is smaller than 0.05, the dielectric loss t
An δ is large and the high temperature load life is short (for example, see Sample No. 16 in Table 1).

When a is larger than 1.0, the relative dielectric constant ε _s
(See, for example, Sample No. 20 in Table 2).

When b is smaller than 0.05, the relative dielectric constant ε _s
And the high-temperature load life is shortened (for example, see Sample No. 12 in Table 1).

When b is larger than 1.0, the relative dielectric constant ε
_s decreases (for example, see Sample No. 15 in Table 1).

When c is smaller than 0.05, the high temperature load life is shortened (for example, see Sample No. 1 in Table 1).

When c was larger than 2.0, the dielectric material was reduced, the insulation resistance IR was reduced, and it was impossible to measure the relative dielectric constant ε _s and the dielectric loss tan δ. Also, the high temperature load life is shortened (for example, see Sample No. 9 in Table 1).

However, even when c is 2.0 or less, M ₃ (Y ₂ O ₃ )
When 1.0 or more or M ₄ (WO ₃ ) was 1.0 or more, the dielectric material was reduced, the insulation resistance IR was reduced, and the measurement of the relative dielectric constant ε _s and the dielectric loss tan δ was impossible. In each case, the high temperature load life is also short (for example, sample No. 1 in Table 1).
10 and Sample No. 6).

[0039]

According to the present invention, a highly reliable dielectric ceramic having a high relative dielectric constant, a small dielectric loss, a long high-temperature load life and a high insulation resistance even when fired in a neutral or reducing atmosphere. A composition can be obtained.

As a result, a multilayer ceramic capacitor using a base metal such as Ni as an internal electrode can be manufactured.

Continuation of front page (56) References JP-A-63-221504 (JP, A) JP-A-63-292508 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 35 / 49

Claims (1)

(57) [Claims] 1. A polycrystalline solid solution containing barium titanate as a main component, wherein the composition formula of the solid solution is ｛Ba (1-x) Ca
x｝ A · ｛Ti (1-y) Zry｝ B · O ₃ + aM ₁ + bM ₂ +
When represented by c (M ₃ + M ₄ ), M ₁ , M ₂ , M ₃ , M ₄
Is a compound of M ₁ : Mn, Cr at least one compound of M ₂ : Si, a compound of M ₃ : Y, a compound of M ₄ : W, and a, b, c are 0.05 ≦ in terms of oxide. a ≦ 1.0 (% by weight based on the ABO ₃ ) 0.05 ≦ b ≦ 1.0 (% by weight based on the ABO ₃ ) 0.05 ≦ c ≦ 2.0 (% by weight based on the ABO ₃ ) (However, the maximum value of M ₃ is 1.0% by weight. , the maximum value of M ₄ is 1.0 wt%) 0 ≦ x ≦ 0.24 0.08 ≦ y ≦ 0.22 1.000 ≦ a / B , characterized in that in the range of ≦ 1.040 nonreducing dielectric ceramic composition.