JPS63117959A - Dielectric ceramic composition - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a dielectric ceramic composition, which can be sintered at a low temperature of 1000'C or less, has a high dielectric constant, has a high insulation resistance at room temperature and high temperature, Furthermore, the present invention relates to a dielectric ceramic composition with high mechanical strength.

"Prior art and its problems" Conventionally, barium titanate (B
Porcelain whose main component is aTi03) has been widely put into practical use, but porcelain whose main component is barium titanate is usually 1.
The sintering temperature is much higher, from 300'C to 1400°C.

Therefore, when using this for multilayer capacitors,
A material that can withstand this sintering temperature must be used for the internal electrodes, for example, an expensive noble metal such as platinum or palladium, which has the disadvantage of increasing manufacturing costs. In order to make a laminated capacitor cheaply, it is necessary to use inexpensive metals mainly composed of silver, nickel, etc., which can be used for the internal electrodes.
There is a need for porcelain that can be sintered at as low a temperature as possible, especially below 1000'C.

Furthermore, the electrical properties of the dielectric ceramic composition are basically required to have a high dielectric constant, low dielectric loss, and high insulation resistance.

In addition, in the case of multilayer chip capacitors, when the chip capacitor is mounted on a board, mechanical distortion is applied to the chip capacitor due to the difference in thermal expansion coefficient between the board and the porcelain that makes up the chip capacitor. Cracks may occur or damage may occur.

In this case, the lower the mechanical strength of the porcelain that forms the capacitor, the more likely it is to crack, break easily, and reduce reliability, so it is extremely important for practical purposes to increase the mechanical strength of the porcelain as much as possible. It is.

In addition, in composite laminated ceramic parts that have a laminated structure of dielectric layers and insulator layers, the sintering temperature of the insulator is 850 to 1000'C, and silver, nickel, etc. are mainly used to reduce costs. Sintering is not possible at temperatures below 1000°C due to the use of inexpensive metals as conductors, the stress between dissimilar materials due to compositing during sintering, and the matching with the shrinkage characteristics of insulators. , dielectric porcelain with high mechanical strength and controlled shrinkage characteristics is required.

By the way, Pb(Mg1/2W172)03 PbT
i 03 P b (M(j1/3 N b2/3
) 03 series is disclosed in JP-A-55-111011, but there is no disclosure regarding specific resistance or mechanical strength, and the practicality of this ceramic composition was not clear.

The present invention has been made in response to the conventional circumstances described above, and has the advantages of being able to be sintered at a low temperature of 1000°C or less, having a high dielectric constant, low dielectric loss, and high insulation resistance. The object of the present invention is to provide a highly reliable porcelain composition that has good electrical properties and high mechanical strength.

[Means for solving the problems] The present invention provides magnesium lead tungstate [Pb (
Mg1/2 Wl/2 ) 03 ] , f Tan ME
[PbT+03] and nickel lead niobate [Pb
A ternary component consisting of (N i 1/3 N b2/3 > 03
> 03] x [PbT! 03 ]y [Pb(
N! Nb2/3 >03]7 (where x+y+z=i, oo), the following composition points (x= 0.693. y= 0.
297. z= 0.01) ・(a)(x= 0.
495. y=0.495. z=0.01)
・(b) (x= 0.195. y= 0.455.
z= 0.35)...(C)(x= 0.10,
y=0.40, z=0.50)...(d
) (x= 0.06, y= 0.24, z=
0.70 > - Manganese lead niobate [Pb (Mn1/3 Nb2/3
> 03 ] to the main component composition from 0.05 to 1
omo 1%, silver 0.02-2 to main component composition
．． A dielectric ceramic composition characterized in that it contains 0% by weight.

A three-component composition diagram showing the main component composition range in the present invention is shown in FIG. In the figure, (a), (b), (cHd), and (e) represent each composition point, and the composition range included in the present invention is the range shown by diagonal lines in the figure and its boundary line.

In a three-component composition diagram showing the main component composition range, the composition point (
b) Outside the line connecting (C) and (d), the Curie point deviates significantly to the higher temperature side than the practical range, so the dielectric constant decreases. On the other hand, outside the line connecting composition points (a) and (e), the Curie point deviates significantly to the lower temperature side than the practical range, so the dielectric constant becomes small and it is not practical. In addition, Pb (Mr11/3 Nb2/3 >
(7) If the amount added is less than 0.05 mO1%, the effect of improving the transverse strength is small, and if it exceeds 10 mO1%, the transverse strength decreases, which is not practical. Further, if the amount of the subcomponent 80 added is less than 0.02% by weight, the effect of controlling the shrinkage rate is small, and if it exceeds 2.0% by weight, the specific resistance becomes small, which is not practical.

[Examples] Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples.

Examples 1-38. Comparative Examples 1 to 22 Lead oxide (PbO) with a purity of 99.9% or more as a starting material
, magnesium oxide (Mc+O), tungsten oxide<
WO3>, titanium oxide (T!02), nickel oxide (
N i O>, niobium oxide (Nb205), manganese carbonate (MnCO3), and silver (AQ) are each weighed so as to have the compounding ratio shown in Table 1. Next, the weighed ingredients were wet mixed using a ball mill, and then
Pre-baking is performed at 00°C, and the powder is pulverized in a ball mill, filtered and dried, and then formed into a green sheet by slip casting film formation method.

The slip casting film forming method involves mixing pre-fired powder with a binder, organic solvent, and organic plasticizer in a homomixer, and drying the slurry flowing out from a doctor blade onto an organic sheet to a thickness of 20μ'rrL to 100μm. This is a technology for forming green sheets.

A large number of green sheets obtained by this method were laminated and hot pressed to create a flat plate with a shape of 20 m' and a thickness of about 1 m. Next, each sample was subjected to a debinding process in the air, and then
Sintering was performed at a temperature of 1000°C for 1 hour.

Silver electrodes were baked on the top and bottom surfaces of the sintered flat plate at 600°C, and a frequency of 1 Kl (Z, voltage 1 yr) was measured using a digital LCR meter.
, m, s, The capacitance and dielectric loss were measured at a temperature of 20'C, and the dielectric constant was calculated.

Next, a voltage of 50 V was applied for 1 minute using a super insulation resistance meter, the insulation resistance was measured at a temperature of 20'C, and the specific resistance was calculated.

In order to evaluate the mechanical properties in terms of bending strength, one rectangular plate with a thickness of 1rfun1 width of 3mm and a length of approximately 15° was prepared from the sintered flat plate.
I cut out 0 pieces. The distance between the fulcrums is 10M degrees τ [kCI/~
I asked for 1. However, ρ is the distance between the supporting points, t is the thickness of the sample, and W is the width of the sample.

The shrinkage rate was calculated from the difference between the dimensions of the shrinkage rate measuring pattern formed on the flat plate of the sample taken out at 850°C and 900'C and the size before firing.

The main component of the porcelain thus obtained [Pb(Mg17
2 Wl/2 ) 03 ]X [PbT ! 03
]s.

[Pb(N!1/3Nb2/3)03]Z blending ratio x1y, z and amount of subcomponents added, dielectric constant, dielectric loss, specific resistance at 20°C, bending strength, and 850°C and 90°C
Table 1 shows the relationship between shrinkage rates at 0'C.

As is clear from the results shown in Table 1, Pb(MQ1/2
W1/2 > 03 PbT! 03 Pb
(N! 1/3 N b2/3 > 03 Pb(M n 1/3 N b2/
3 > 03 and AQ within the range of the present invention have a high dielectric constant of 3210 to 12320,
Dielectric loss is small at 0.2-2.9%, resistivity is 20'
3.6 x 1012 to 1.9 x 1013 Ω at C”
cm, and has a bending strength of 1100 to 1380'KQ/
The shrinkage rate is controlled to 9.8-10.8% at 850°C and 12.8-13.2% at 900'C. This value almost matches the shrinkage rate of the insulator of composite laminated ceramic parts.

FIG. 2 shows each composition point in the blending ratio of the main components used in the Examples and Comparative Examples. In the diagram, numbers 1, 2゜3...20
are each composition point corresponding to the main component blending ratio number shown in Table 1.

[Effects of the Invention] As explained above, since the dielectric ceramic composition of the present invention has a low sintering temperature of 1000'C or less, it is possible to reduce the cost of internal electrodes in multilayer capacitors and save energy. It also saves on furnace materials.

Furthermore, the obtained ceramic composition has excellent physical properties and electrical properties and is highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the main component composition range of the present invention, and FIG. 2 is a diagram showing the relationship between the main component composition range of the present invention and the composition points shown in Examples and Comparative Examples.

Claims (1)

[Claims] Magnesium lead tungstate [Pb (Mg_1_/_2W_1_/_2)O_3], lead titanate [PbTiO_3] and nickel lead niobate [
A three-component composition consisting of [Pb(Mg_1_/_2W_1
___/_2)O_3]_x[PbTiO_3]_y[Pb
(Ni_1_/_3Nb_2_/_3)O_3]_z (however, x+y+z=1.00), the following composition points (x=0.693, y=0, 297, z=0) in this three-component composition diagram .01)(
x=0.495, y=0.495, z=0.01) (x
=0.195, y=0.455, z=0.35) (x=
0.10, y=0, 40, z=0.50) (x=0.0
Manganese lead niobate [Pb(Mn_1_/_
3Nb_2_/_3)O_3] to the main component composition, 0.05 to 10 mol%, and silver to the main component composition, 0.05 to 10 mol%.
．． 1. A dielectric ceramic composition comprising: 0.02 to 2.0% by weight.