JPH0419648B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a porcelain composition that can be sintered at low temperatures, sometimes below 1000°C, has a high dielectric constant, low dielectric loss,
The present invention relates to a ceramic composition that has high insulation resistance and 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 1000°C, is needed. Additionally, the electrical properties of the 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 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, in the case of a dip capacitor 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 that the capacitor is made of, the more likely 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. The purpose of the present invention is to sinter in the low temperature range of 900 to 1000℃, have excellent electrical properties such as high dielectric constant, low dielectric loss, and high insulation resistance, and in particular, have high mechanical strength and high reliability. An object of the present invention is to provide a porcelain composition. The porcelain composition of the present invention has lead nickel tungstate [Pb(Ni _1/2 W _1/2 ) O ₃ ] and lead titanate [PbTiO ₃ ] as main components, and its composition is [Pb
(Ni _1/2 W _1/2 ) O ₃ ] _x [PbTiO ₃ ] A subcomponent is added to the main component composition in which the main component blending ratio x, expressed as _1-x, is within the range of 0.30≦x≦0.60. as manganese (Mn)
It is characterized by containing 0.01 to 1 atomic % of the above-mentioned main component composition. Hereinafter, the present invention will be explained in detail with reference to examples thereof. Lead oxide (PbO), nickel oxide (NiO), tungsten oxide (WO ₃ ), titanium oxide (TiO ₂ ), and manganese carbonate (MnCO ₃ ) with a purity of 99.9% or higher were used as starting materials, and the results were as shown in Table 1. After wet-mixing each weighed material in a ball mill so that the mixing ratio is achieved, pre-baking is performed at 750-800℃, this powder is pulverized in a ball mill, divided into portions, dried, an organic binder is added, and the mixture is prepared. After the grains were pressed, four disks with a diameter of 16 mm and a thickness of about 2 mm and a cylinder with a diameter of 16 mm and a thickness of about 10 mm were produced as samples. Next, this sample was sintered in air at a temperature of 900 to 1000℃ for 1 hour, silver electrodes were baked at 600℃ on the top and bottom surfaces of four sintered disks, and a digital LCR meter frequency was 1KHz.
The capacitance and dielectric loss were measured at a voltage of 1 Vr.ms and a temperature of 20°C, and the dielectric constant was calculated. Next, check 50V using a super insulation resistance tester.
The voltage was applied for 1 minute, the insulation resistance was measured at a temperature of 20°C, and the specific resistance was calculated. In order to evaluate the mechanical properties by bending strength, a sintered cylinder with a thickness of 0.5 mm,
Ten rectangular plates with a width of 2 mm and a length of 13 mm were cut out. Using the three-point method with a distance between fulcrums of 9mm, the breaking load Pm
[Kg] was measured, and the bending strength τ [Kg/cm ² ] was determined according to the formula: τ=2/3Pml/Wt ² [Kg/cm ² ]. However, l is the distance between the supporting points, 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 composition thus obtained [Pb
(Ni _1/2 W _1/2 ) O ₃ ] _x [PbTiO ₃ ] The relationship between the compounding ratio x of _1-x and the amount of added subcomponents, dielectric constant, dielectric loss, specific resistance and bending strength is shown in Table 1. Shown below. Note that samples marked with * are not included in the scope of the present invention.

【table】

[Table] As is clear from this result, the material of the present invention has a high dielectric constant of 1100 to 6900 and a dielectric loss of 0.3.
〜2.6%, specific resistance 1×10 ¹¹ 〜2〜
A highly reliable and highly practical ceramic composition was obtained which exhibited a high value of 10 ¹³ Ω·cm and also had a transverse strength of 950 to 1460 Kg/cm ² , which was sufficiently high for practical use. The porcelain of the present invention, which exhibits such excellent properties, is sintered at a low temperature of 1000°C or less, making it possible to reduce the cost of internal electrodes in multilayer capacitors, as well as save energy and furnace materials. Excellent effects also occur. In addition, the main component blending ratio x
When x<0.30, the Curie temperature becomes too high than the practical range, the dielectric constant at room temperature becomes small, and the dielectric loss becomes large, which is not practical. If x > 0.60, it will not be sintered as porcelain 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.

Claims (1)

[Claims] 1. Lead nickel tungstate [Pb(Ni _1/2
The main components are [Pb(Ni _{1/2 W 1/2} )O ₃ ] and lead titanate [PbTiO ₃ ], and the composition is [Pb(Ni _1/2 W _1/2 )O ₃ ] _x
[PbTiO ₃ ] When expressed as _1-x , the main component blending ratio x is
The main component composition is within the range of 0.30≦x≦0.60,
A porcelain composition characterized in that it contains manganese (Mn) as a subcomponent in an amount of 0.01 to 1 atomic % based on the main component composition.