JPH03238706A - Dielectric porcelain composition and condenser - Google Patents

Abstract

PURPOSE:To obtain a dielectric porcelain composition for which a short-time baking is possible without sacrificing a high dielectric constant by adding a specific mol% of lead oxide (PbO) and nitrogen oxide(NiO) to a tentatively baked powder of a primary component dielectric porcelain composition formed out of the values within a specific region. CONSTITUTION:Referring to an expression I in which a dielectric porcelain composition has a perovskite structure, (a) is in a range of 0.001<=a<=0.225, and to the value of (a) within this range, 1.0-25.0mol% of lead oxide (PbO) as well as 1.0-15.0 mol% of nitrogen oxide (NiO) or 1.0-15.0mol% of tungsten trioxide (WO3) are added to a tentatively baked powder of a primary component dielectric porcelain composition formed out of the values in the region formed in a pentagon with tops of compositions A-E expressed by the values in the parenthesis of an expression V, in trigonometric coordinates with tops of expressions II-IV. In the expression I, (x)-(z) express x+y+z=1. A ceramic condenser can thus be obtained which has a dielectric constant high enough for baking even in a neutral or reducing atmosphere for a short period of time at a temperature of 800-1000 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a dielectric ceramic composition that can be fired at a firing temperature of 800 to 1000°C in a short time in a neutral atmosphere or a reducing atmosphere, and has a high resistivity. Concerning objects and capacitors.

Conventional Technology Materials containing barium titanate as a main component have been used as high dielectric constant materials for ceramic capacitors, which are becoming smaller and larger in capacity. However, in order to sinter this material, it is necessary to use high-temperature firing temperatures of around 1,300°C in the atmosphere, so when manufacturing multilayer ceramic capacitors, expensive noble metals such as platinum or palladium are used as electrode materials. In particular, as capacity increases, the internal electrode material becomes a factor pushing up raw material costs.

In contrast, in recent years, methods have been developed to make barium titanate-based materials more resistant to reduction, using inexpensive base metals as electrode materials and firing them in an atmosphere with low oxygen partial pressure, and using lead-based dielectric materials and inexpensive silver. The cost of multilayer ceramic capacitors has been reduced by using a silver-palladium alloy as the main electrode material and firing at a low temperature of around 1000°C.

On the other hand, in electronic devices where miniaturization and high reliability are desired, hybrid ICs with high packaging density are being used, and there is an increasing demand for thick film capacitors in place of conventional chip capacitors.

In order to manufacture this thick film capacitor, a dielectric material that can be fired at low temperatures and for a short period of time is required, and lead-based dielectric materials are mainly used as the material for this purpose. Therefore, lead-based dielectrics are being actively developed as a material that can be fired at low temperatures and can be used to increase the capacity of multilayer ceramic capacitors or to increase the thickness of capacitors.

Problems to be Solved by the Invention Now, (Pb+, ooCaa)(Mg+/3Nb2
/3) Oa+a.

(Pb+, oocaa)T i03+2, (
Pb+ , ooCaa ) (N i + 72W+ /
2) 03+a type dielectric composition is disclosed in Japanese Patent Application Laid-Open No. 62-874.
As known from Publication No. 55, it is a dielectric constant ceramic composition fired in a low oxygen atmosphere at 1100°C or less,
In order to increase the dielectric constant and obtain a sufficiently dense fired body, it is necessary to hold the fired body at the firing temperature for several hours. -Hybrid I
When producing a thick film capacitor for C, low-temperature, short-time firing is essential, and under such conditions the dielectric material becomes unfired, so there is a problem that desired characteristics cannot be obtained.

In view of this problem, in the present invention, (Pb+,ooCaa)(Mg+/3Nb2/3)0
3+-a*(Pb+, HCaa)T! 03+
a, (Pb+, ooca2)(N i +/z
W+ /2) 0:++ 80% in a neutral or reducing atmosphere without impairing the high dielectric constant of the a-based solid body.
The object of the present invention is to provide a dielectric ceramic composition that can be fired at 0 to 1000°C for a short period of time, and a ceramic capacitor or thick film capacitor using the same.

Means for Solving the Problems In order to solve the above problems, the dielectric ceramic composition of the present invention comprises (Pb+, ooCaa)(Mg+/3Nb2/3
)xTiy(NiI/2W+/2)z03+a (X+37+Z-1) is in the range of 0.001≦a≦0.225, and for the value of a within this range , (Pb+
,ooCaa)(Mg+/3Nbz/z)03+a.

(Pb+, 0OCaa)T i03+a, (
Pb+ , ooCa, )(Ni +72W+ /2
) Hypothetical main component dielectric ceramic composition consisting of a pentagonal area with compositions A, B, C, D, and E as vertices, expressed by the numbers in brackets below, using triangular coordinates with 03+1 as the apex. 1.0 to 25.0 mol% of PbO and Ni to the sintered powder
1.0-15.0 mol% O or 1.0 mol% W O3
In other words, the composition according to the claims of the present invention has a perovskite structure (Pb+, ooCaa
)(Mg+/3Nb2/3)03+a-(Pb+,oo
Caa)Ti03+a (Pb+,ooCaa)(Ni
+72W+/x)03+a By adding PbO1 and NiO or W O3 to the calcined powder, Pb
Utilizing the eutectic composition of O and NiO or WO3, a liquid phase is generated at low temperatures, and these additives are dissolved simultaneously in both sites A and 8, allowing smooth diffusion into the dielectric material. By suppressing the formation of grain boundary layers due to A ceramic capacitor or thick film capacitor with a large capacity can be obtained.

Example Examples of the present invention will be shown below.

<Example 1> First, as starting materials, chemically highly purified Pbo, Ca
CO3, MgO, Nb2O5, T i 02゜NiO,
WO3 was used. After correcting the purity of these, a predetermined amount was weighed, pure water was added, and the mixture was mixed for 17 hours in a ball mill using agate cobblestones. This is filtered by suction to remove most of the moisture, dried, and then thoroughly crushed in a Raikai machine. 5wt% of the crushed amount of pure water is added to form a cylinder with a diameter of 60mm and a height of approximately 50mm. Molding was carried out at a molding pressure of 500 kg/c-. Place this in an aluminum pot and cover it with a homogeneous lid.750
It was calcined at ~1000°C for 2 hours. Next, the calcined product was roughly crushed in an alumina mortar, further crushed in a ball mill for 17 hours, filtered under suction, and then dried. The above steps of calcination, crushing, and drying were repeated several times. This powder was analyzed by X-ray analysis and confirmed to be a perovskite phase.

PbO and NiO or WO3 are added as subcomponents to this dielectric powder, and after mixing in a Raikai machine, a 6 wt% aqueous solution of polyvinyl alcohol is added to 6 wt% of the powder amount.
In addition, it was granulated through a 32-mesh sieve, and the molding pressure was 5.
Diameter 131.00 far/cd. It was molded into a disk shape with a height of about 5+ m. Next, this molded product was exposed to air for 600 min.
After holding at ℃ for 1 hour to remove the binder, it was placed in a magnesia porcelain container with a homogeneous lid, and heated to a specified temperature in a neutral or reducing atmosphere using an atmospheric belt furnace for 2 hours.
The temperature was raised at 400°C/hrs, held at the maximum temperature for 10 minutes, and then lowered at 2400°C/hrs.

The fired product obtained in the above manner was processed into a disk shape with a thickness of 1 inch, Cr-Ag was deposited as an electrode on both sides, and the dielectric constant and tan δ were measured at IKHz under an IV/Uji electric field. .

Further, for resistivity, the value of IS was determined after applying a voltage of 30 V to the sample.

Table 1 below shows the material composition of the present invention and the dielectric properties and resistivity of the fired product when the firing atmosphere was nitrogen, which is a neutral atmosphere. Further, the dielectric properties and resistivity of the fired product are shown in Table 2 below when the firing atmosphere is a nitrogen-hydrogen mixed gas having an oxygen partial pressure of 10 atm or more.

(Hereinafter, blank) As shown in Tables 1 and 2 above, the fired products according to the material composition of the present invention have good performance in firing at 800 to 1000°C for a short time and in various atmospheres. Also, a dense fired body with a high dielectric constant can be obtained, and by adding calcium, it can be fired in a neutral or reducing atmosphere.
A fired body with high resistivity was obtained.

FIG. 1 shows the composition range of the main components of the present invention (PbI,
ooCaa) (Mg+/5Nb2/3)03+a.

(PbI, (IgCaa)TiO3+a, (PbI
,0OCaa)(Ni l/2'thy2)Os+
It is shown in a triangular composition diagram with a as the main component.

Here, in the present invention, the claims are defined as (PbI
, 0OCaa)(Mg+/3Nb2/3)xT
1y(N i l /2'tJ+ /2)zo3+
Porcelain composition represented by a (x+y+-2-1)
is in the range of 0.001≦a≦0.225, and for the value of a within this range, (PbI
,ooCaa)(Mg+/3Nb2/3)03+a.

(PbI, ooCaa)Ti03+, , (P
bI,ooCaa)(Ni l/2'tJl/2
) In the triangular coordinates with 03+11 as the apex, the hypothetical main component dielectric porcelain composition consisting of a pentagonal area with the composition A, B, C, D, and E as the vertices, represented by the numbers in 1 below. 1.0 to 25.0 mol% of PbO and N to the sintered powder
1.0 to 15.0 mol% iO or 1.0 WO3
-15.0 mol% was specifically limited to the addition of auxiliary agents, as shown in the comparative examples in Tables 1 and 2, in compositions outside the scope of the invention. If the amount of the composition is small and the firing temperature is lower than 800°C, the firing will be insufficient and a dense fired body will not be obtained, and if the firing temperature is higher than 1000°C, the dielectric constant will significantly decrease due to the reaction of the auxiliary agent to the dielectric material. This is because it decreases. If a is smaller than 0.001, the resistivity of the fired product will be low (and if a is larger than 0.225, the dielectric constant will drop significantly, and x, y
This is because a composition in which , z is outside the specified range has the disadvantage that a high dielectric constant cannot be obtained.

If the composition is outside the limited range, specifically, the dielectric constant of the fired body becomes 3000 or less under the main firing conditions, or the resistivity of the fired body becomes 10IOc11·Ω or less, and the desired characteristics as a capacitor cannot be obtained.

<Example 2> PbO and NiO or WO3 were added as subcomponents to the dielectric powder calcined, crushed and dried in the same manner as in Example 1, wet mixed in a ball mill and then dried to obtain a mixture containing mainly ethyl cellulose. A vehicle in which the component resin was dissolved in a solvent was added, and the mixture was kneaded with a three-stage roll to produce a dielectric paste. Meanwhile, in order to form a thick film capacitor having a 2x2-2 shape on an alumina substrate with a purity of 96%, a copper electrode was printed as a lower electrode and dried. Next, the dielectric paste was printed and dried twice to a thickness of 50 to 60 μm as a dielectric layer, and a copper electrode, which was the same as the lower electrode, was printed and dried as an upper electrode. A printed thick film with a three-layer structure of electrodes was formed and fired in nitrogen using a belt furnace at a maximum temperature of 800 to 1000°C for a holding time of 10 minutes. The dielectric constant tan δ of the thick film capacitor thus obtained is I KHz, I V/rv
Measurements were made under an electric field of a. Further, the resistivity was determined as a value for 1 minute after applying a voltage of 30 V to the sample. Table 3 below shows the material composition of the present invention and the dielectric properties of the fired product fired at 900° C. in nitrogen.

(Left below) As shown in Table 3 above, the fired product of the material composition of the present invention is a dense fired product with high resistivity and high capacity despite being fired at a low temperature and for a short time. A thick film capacitor was obtained.

The reason for limiting the scope of claims is as in Example 1,
As shown in the comparative example in Table 3, when the composition is outside the limited range, the dielectric constant of the fired product is 2500 or less under the main firing conditions, or the resistivity of the fired product is 10IOΩ or less, making it difficult to use as a thick film capacitor. This is because the desired characteristics cannot be obtained.

Although this example showed that firing is possible in nitrogen, it is easily inferred that firing is also possible in a neutral atmosphere such as argon or helium.

Note that as the electrode used in the present invention, an electrode that can be fired at 800 to 1000° C. in a neutral atmosphere or a reducing atmosphere is appropriately selected and used.

Effects of the Invention As described above, the present invention provides (Pbt,ooCaa)(111g + /3Nb
2/3) x T 1Oy (N i I /2WI /2
)zfh+s porcelain composition (where x+y
+z=1), it is in the range of 0.001≦a≦0.225, and for the value of a within this range, (Pbt
,ooCaa)(Mg+/3Nb2/3)03+a*
(Pbt, ooCa, )Ti03+a, (Pbt
, ooca* ) (Ni I/2WI/2 )03
Calcination of a main component dielectric ceramic composition consisting of a pentagonal area with compositions A, B, C, D, and E as vertices, expressed by the following numerical values in [1] in triangular coordinates with +a as the apex. 1.0 to 25.0 mol% of PbO and 1% of NiO to the powder.
．． 0 to 15.0 mol% or 1.0 to 15 W O3
．． By adding 0 mol%, 800~
It has a high dielectric constant that allows it to be fired at a temperature of 1000°C in a short time and even in a neutral or reducing atmosphere.
Moreover, it exhibits the excellent effect of being able to provide a multilayer ceramic capacitor and a thick film capacitor with high resistivity.

[Brief explanation of drawings]

Figure 1 shows the composition range of the present invention (Pbt, ooCas) (Mg+/3Nb2/s
)034+1 *(Pbt,ooCaa)Ti03
+s, (Pbt, ooCaa) (Ni I/2W
+/2) (This is a triangular composition diagram with has as the main component. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 1 (Pbt, oo Co -) (Mg'/3 Nb'
/3) 0stQ(PbtooCαo 2(N+'
/z W 4] 0sta (Pbloo CQa) DingtO
sta

Claims (4)

[Claims] (1) (Pb_1_._0_0Ca_a) (Mg_1_
/_3Nb_2_/_3)_xTi_y(Ni_1_/
In the porcelain composition represented by (_2W_1_/_2)_zO_3_+_a (where x+y+z=1), it is in the range of 0.001≦a≦0.225, and for the value of a within this range, (Pb_1
＿． _0_0Ca_a)(Mg_1_/_3Nb_2
___/_3)O_3_+_a), (Pb_1_._0_0Ca_a)TiO_3_+_a
, (Pb_1_._0_0Ca_a) (Ni_1_/_
2_W_1_/_2) O_3_+_a is the triangular coordinate with the vertex, and the compositions A, B, expressed by the numbers in brackets below,
PbO was added from 1.0 to
A dielectric ceramic composition characterized by adding 25.0 mol% of NiO and 1.0 to 15.0 mol% of NiO. A is x=0.950, y=0.049, z=0.001
, B is x=0.750, y=0.249z=0.001
, C is x=0.001, y=0.800, z=0.19
9.D is x=0.001y=0.450,z=0.54
9. E is x=0.700, y=0.100. z=0.2
00. (2) 1.0 to 25.0 mol% of PbO and W to the calcined powder of the main component dielectric ceramic composition according to claim 1;
A dielectric ceramic composition characterized in that 1.0 to 15.0 mol% of O_3 is added. (3) using the dielectric ceramic composition according to claim 1 or 2;
800-1000 in neutral or reducing atmosphere
A ceramic capacitor characterized by comprising an electrode that can be fired at ℃. (4) A dielectric layer made of the dielectric ceramic composition according to claim 1 or 2 on a ceramic substrate and heated at 800 to 1000°C.
A thick film capacitor characterized in that it is configured by providing an electrode that can be fired with.