JPH0457631B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a porcelain composition, particularly a porcelain composition that can be sintered at a low temperature of 1100° C. or lower, has a high dielectric constant, has a high insulation resistance at room temperature and high temperature, and has high mechanical strength. It is well known that ceramics containing barium titanate (BaTiO ₃ ) as a main component have been widely put into practical use as dielectric ceramic compositions. However, those whose main component is barium titanate (BaTiO ₃ ) have a sintering temperature of usually 1300 to 1400°C. Therefore, when using this material in a multilayer capacitor, a material that can withstand this sintering temperature must be used for the internal electrodes, such as an expensive noble metal such as platinum or palladium, which has the disadvantage of high manufacturing costs. be. In order to make multilayer capacitors cheaply, it is necessary to use inexpensive metals mainly composed of silver, nickel, etc., which can be used for the internal electrodes.
Porcelain that can be sintered at as low a temperature as possible, especially below 1100°C, is needed. Furthermore, the electrical properties of the ceramic composition are basically required to have a high dielectric constant, low dielectric loss, and high insulation resistance. Furthermore, regarding the insulation resistance value, MIL-C-55681B of Military Specification, which is a US Department of Defense standard that requires highly reliable components.
In addition to the value at room temperature, the value at 125℃
The value of is also determined. As can be seen from this, in order to obtain a highly reliable ceramic capacitor, it is necessary to have a high insulation resistance value not only at room temperature but also at the expected highest operating temperature. In addition, in the case of multilayer chip capacitors, when the chip capacitor is mounted on a board, mechanical strain 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. This may cause cracks or damage. Furthermore, even in the case of dip capacitors coated with epoxy resin or the like, cracks may occur in the dip capacitor due to the stress of the coating resin. In either case,
The lower the mechanical strength of the porcelain forming the capacitor, the easier it is to crack and break, resulting in lower reliability. Therefore, it is of practical importance to increase the mechanical strength of porcelain as much as possible. By the way, Pb(Mg _1/2 W _1/2 )O ₃ -PbTiO ₃ based ceramic composition has already been reported in N. N. Krajnik, A. Ai. Agranovskaya NNKrainik and
AIAgrarovskaya (Fiziko Tverdogo Tela,
Vo.2, No.1.pp70-72, Janvara 1960), and (SrxPb _{1-x TiO3} ) _a (PbMg _0.5 W _0.5
O ₃ ) _b [However, x=0~0.10, a=0.35~0.5, b
=0.5 to 0.65, a+b=1], a monolithic capacitor and its manufacturing method were published in Japanese Patent Application Laid-Open No.
It is disclosed in Japanese Patent Application Laid-Open No. 52-21662, and as a dielectric powder composition in Japanese Patent Application Laid-open No. 52-21699. However, none of them discloses any specific resistance, and the practicality of these ceramic compositions is unknown. On the other hand, the inventors have already
Can be sintered at temperatures of ~950℃, Pb(Mg _1/2 W _1/2 ) O ₃ and
It consists of a two-component system with PbTiO ₃ , which is combined with [Pb
We proposed a composition in which x is in the range of 0.65<x≦1.00 when expressed as (Mg _1/2 W _1/2 )O ₃ ] _x [PbTiO ₃ ] _1-x . This composition has a high product of dielectric constant and specific resistance, and has excellent electrical properties with low dielectric loss. However, since all of the above compositions have low mechanical strength, their applications have had to be limited to a narrow range. In addition, 3 containing Pb(Mg _1/2 W _1/2 ) O ₃ −PbTiO ₃ system
Regarding the component system, see JP-A-55-111011.
Pb(Mg _1/2 W _1/2 )O ₃ −PbTiO ₃ −Pb(Mg _1/3 Nb _2/3 )
The O ₃ system was introduced in Japanese Patent Application Laid-Open No. 117809/1983 as Pb (Mg _1/2
W _1/2 )O ₃ −PbTiO ₃ −Pb(Mg _1/3 Ta _2/3 )O ₃ system is
Each is disclosed. However, none of them discloses specific resistance or mechanical strength, and the practicality of these ceramic compositions is unclear. In addition, the present inventors have already discovered Pb(Mg _1/2 W _1/2 )O ₃ −
A ternary composition of _PbTiO3 -Pb(In1 _/ 2Nb1 _/2 ) _O3 is proposed. This composition can be sintered in the low temperature range of 900 to 1100°C, has excellent properties such as high dielectric constant, low dielectric loss, and high insulation resistance at room temperature and high temperature. However, since this composition has low mechanical strength, its use has had to be limited to a narrow range. In view of the above points, the present invention provides temperature control of 900 to 1100℃.
A highly reliable porcelain composition that can be sintered in the low-temperature region of Magnesium lead tungstate [Pb (Mg _1/2 W _1/2 ) O ₃ ], lead titanate [PbTiO ₃ ]
and indium lead niobate [Pb (In _1/2 Nb _1/2 )
A _three -component composition consisting of [Pb (Mg _1/2 W _1/2 )
When expressed as O ₃ ] _x [PbTiO ₃ ] _y [Pb (In _1/2 Nb _1/2 ) O ₃ ] _z (however, x+y+z=1.00), this 3
In the composition diagram, the following composition points: (x=0.796, y=0.199, z=0.005) (x=0.48, y=0.12, z=0.40) (x=0.21, y=0.09, z=0.70) ( x = 0.12, y = 0.18, z = 0.70) (x = 0.398, y = 0.597, z = 0.005) In the main component composition in the composition range surrounded by these five points, as a subcomponent, It is characterized by containing manganese [Mn] in an amount of 0.01 to 1 atomic % based on the main component. Hereinafter, the present invention will be explained in detail with reference to Examples. Lead oxide (PbO), magnesium oxide (MgO), tungsten oxide (WO ₃ ), titanium oxide (TiO ₂ ), indium oxide (In ₂ O ₃ ), and niobium oxide (Nb ₂ O ₅ ) with a purity of 99.9% or higher are used as starting materials. ) and manganese carbonate (MnCO ₃ ), and weigh each to achieve the mixing ratio shown in the table. Next, after wet-mixing each weighed material in a ball mill, 750 to 800
The powder was pre-baked at ℃, then ground in a ball mill, separated, dried, added an organic binder, sized and pressed, and used as samples: four disks with a diameter of 16 mm and a thickness of about 2 mm; A cylinder with a thickness of approximately 10 mm was created. Next, the sample was sintered in air at a temperature of 900 to 1100℃ for 1 hour, and silver electrodes were baked at 600℃ on the top and bottom surfaces of the four sintered disks, and a digital LCR meter was used at a frequency of 1KHz and a voltage of 1Vr.ms. The capacitance and dielectric loss were measured at 20°C, and the dielectric constant was calculated. Next, a voltage of 50V was applied for 1 minute using a super insulation resistance meter, insulation resistance was measured at temperatures of 20°C and 125°C, and specific resistance was calculated. In order to evaluate the mechanical properties in terms of bending strength, 10 rectangular plates with a thickness of 0.5 mm, a width of 2 mm, and a length of about 13 mm were cut out from the sintered cylinder. The distance between the fulcrums was set to 9 mm, and the breaking load Pm [Kg] was measured using the two-point method, and τ =
The bending strength τ [Kg/cm ² ] was determined according to the formula: 3Pml/2Wt ² [Kg/cm ² ]. However, l is the distance between the fulcrums,
t is the thickness of the sample, and W is the width of the sample. The electrical properties were determined from the average value of 4 disk samples, and the bending strength was determined from the average value of 10 rectangular plate samples. The main component of the porcelain obtained in this way [Pb (Mg _1/2 W _1/2 ) O ₃ ] _x
[PbTiO ₃ ] _y [Pb (In _1/2 Nb _1/2 ) O ₃ ] _z blending ratio x,
y, z and amount of subcomponents added, dielectric constant, dielectric loss,
The relationship between specific resistance and bending strength at 20°C and 125°C is shown in the table below.

【table】

[Table] As is clear from the results shown in the table, Pb
(Mg _1/2 W _1/2 )O ₃ −PbTiO ₃ −Pb(In _1/2 Nb _1/2 )O ₃
A three-component composition containing Mn as a subcomponent in a specific proportion has a dielectric constant of 1010 to 3540.
It has a high dielectric loss of 0.2 to 2.9%, and a high specific resistance of 1.5×10 ¹² to 7.2×10 ¹³ Ω・cm at 20°C, and 7.0×10 ¹⁰ to 1.1×10 ¹³ even at 125°C.
It shows a high value of Ω・cm, and also has a high bending strength.
It can be seen that this is a highly reliable and extremely practical porcelain composition that exhibits a value of 970 to 1460 Kg/cm ² , which is sufficiently high for practical use. . The porcelain composition of the present invention, which exhibits such excellent properties, has a low sintering temperature of 1,100°C or less, which makes it possible to reduce the cost of the internal electrodes of multilayer capacitors, and also to save energy and furnace materials. An extremely excellent effect also occurs. The figure shows the main component composition range of the present invention. The numbers shown in the figure correspond to the numbers of the main component blending ratios shown in the table. The present invention uses the main component composition as [Pb (Mg _1/2 W _1/2 )
When expressed as O ₃ ] _x [PbTiO ₃ ] _y [Pb (In _1/2 Nb _1/2 ) O ₃ ] _z (where x+y+z=1.00), the composition range is (x=0.796, y=0.199) , z=0.005) (x=0.48, y=0.12, z=0.40) (x=0.21, y=0.09, z=0.70) (x=0.12, y=0.18, z=0.70) (x=0.398, y = 0.597, z = 0.005) and the composition range surrounded by these five points, and the added content of the subcomponent is limited to 0.01 to 1 atomic % with respect to the main component. In addition, in the main component composition range, outside the line connecting composition points 2 and 15, the specific resistance at high temperature becomes small and is not practical. Outside the line connecting composition points 15, 16, 7, 3, and 2, the dielectric constant becomes small and is not practical. Furthermore, if the amount of the subcomponent Mn added is less than 0.01 atomic %, the effect of improving the flexural strength is small, and if it exceeds 1 atomic %, the flexural strength decreases, which is not practical.

[Brief explanation of the drawing]

The figure is a diagram showing the main component composition range of the present invention and the composition points shown in Examples.

Claims (1)

[Claims] 1. Magnesium lead tungstate [Pb
(Mg _1/2 W _1/2 ) O ₃ ], lead titanate [PbTiO ₃ ] and lead indium niobate [Pb (In _1/2 Nb _1/2 ) O ₃ ]
A three-component composition consisting of [Pb(Mg _1/2 W _1/2 ) O ₃ ] _x
When expressed as [PbTiO ₃ ] _y [Pb (In _1/2 Nb _1/2 ) O ₃ ] _z (where x+y+z=1.00), in this three-component composition diagram, the following composition points (x=0.796, y=0.199, z=0.005) (x=0.48, y=0.12, z=0.40) (x=0.21, y=0.09, z=0.70) (x=0.12, y=0.18, z=0.70) (x= 0.398, y = 0.597, z = 0.005) and in the composition range surrounded by these five points, manganese (Mn) is added as a subcomponent in an amount of 0.01 to 1 atomic % based on the main component. A porcelain composition comprising: