JPH10265261A - Dielectric porcelain composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric porcelain compsn. having high insulation resistance and a high relative dielectric constant by providing a specified compsn. consisting of PbO, MgO, TiO2 and Nb2 O5 . SOLUTION: This dielectric porcelain compsn, is represented by the formula sPbO.tMgO.uTiO2 .vNb2 O5 , [where (s), (t), (u) and (v) show molar ratio, 5.0<=s<=15.5, 40.0<=t<=50.0, 40.0<=u<=50.0, 1.0<=v<=6.0 and s+t+u+v=100.0] and has a relative dielectric constant of >=30, a Q value of >=100, >=5×10<12> Ω.cm insulation resistance and -500 to +1,800 ppm/ deg.C temp. coefft. of relative dielectric constant. Powders of PbO, MgO, TiO2 and Nb2 O5 as starting materials are mixed in a prescribed ratio, calcined at 1,000-1,050 deg.C, pulverized, granulated with an org. binder, compacted in a prescribed shape and fired at 1,150-1,250 deg.C to obtain dielectric porcelain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a temperature-compensating dielectric porcelain composition useful as a dielectric material for a multilayer capacitor.

[0002]

2. Description of the Related Art Temperature-compensating dielectric ceramic capacitors are widely used in communication equipment and the like. Dielectric materials used for such applications generally have a large relative dielectric constant, a large Q (that is, a small dielectric loss), and a temperature coefficient of the relative dielectric constant within a range of -750 to +100 ppm / ° C. Some characteristics are required.

Heretofore, CaTiO ₃ —MgTiO ₃ based materials and the like have been known as a temperature compensating dielectric porcelain composition. This material has a large Q (usually about 10,000) with a relative dielectric constant of about 20 to 30. The temperature coefficient of the relative permittivity is about -30 to +30 ppm / ° C.

[0004] In the field of communication devices such as mobile phones, the size of devices has been further reduced in recent years.
Accordingly, the demand for miniaturization of components used in these devices has been further increased. However, with the relative dielectric constant of the conventional dielectric ceramic composition as described above, there is a limit to miniaturization of components, and it is considered that a material having a larger relative dielectric constant is required for miniaturization.

As materials having a large relative dielectric constant of 100 or more, CaTiO ₃ and SrTiO ₃ are known, and the temperature coefficient of the relative dielectric constant of these materials is -1850, respectively.
ppm / ° C. and −3000 ppm / ° C., which are large negative values.

As described above, it is difficult to develop a dielectric material which has a large relative dielectric constant and a high Q value by itself and satisfies all the conditions that the absolute value of the temperature coefficient of the relative dielectric constant is small. Conventionally, attempts have been made to develop a material having the characteristics of each material by mixing two or more dielectric materials.

[0007]

When a material satisfying the required characteristics is realized by combining two or more dielectric materials, for example, the relative permittivity of CaTiO ₃ or SrTiO ₃ is large, and the temperature of the relative permittivity is large. In order to obtain a material having a large relative permittivity and a high Q value and a small absolute value of the temperature coefficient of the relative permittivity by combining with a material having a large negative coefficient,
A material that has a large relative dielectric constant and a high Q value itself and has characteristics such as a temperature coefficient of the relative dielectric constant being positively large is desired.

Further, from the viewpoint of expanding the range of application of the material by such a combination, a material which can arbitrarily control the temperature coefficient of the relative permittivity in a wide range by changing the material composition ratio is desired.

Further, in the dielectric ceramic composition, a high insulation resistance is a fundamental required characteristic.

The present invention has been made in view of the above conventional circumstances, and has a relative dielectric constant of 30 or more, a Q of 100 or more,
The insulation resistance is as large as 5 × 10 ¹² Ω · cm or more, and the temperature coefficient of relative permittivity is from −500 ppm / ° C. to +1800 ppm /
It is an object of the present invention to provide a dielectric porcelain composition that can be arbitrarily controlled in the range of ° C.

[0011]

The dielectric porcelain composition of the present invention is a porcelain composition consisting of PbO, MgO, TiO ₂ and Nb ₂ O ₅ , wherein the composition formula is sPbO.tMgO.uTi.
When represented by O ₂ · vNb ₂ O ₅ , s, t, u, and v are represented by mole fractions 5.0 ≦ s ≦ 15.0 40.0 ≦ t ≦ 50.0 40.0 ≦ u ≦ 50. 0 1.0 ≦ v ≦ 6.0 where s + t + u + v = 100.0.

As represented by the above composition formula, PbO, M
gO, by mixing TiO ₂ and Nb ₂ O ₅ in a predetermined ratio, dielectric constant, Q and insulation resistance is large, -5
A dielectric ceramic having a relative dielectric constant temperature coefficient controllable in the range of 00 to +1800 ppm / ° C. can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The dielectric ceramic composition for temperature compensation of the present invention comprises:
PbO, MgO, consists TiO ₂ and Nb ₂ O _5, its composition formula _{sPbO · tMgO · uTiO 2 · vNb} 2
When represented by O ₅ , s, t, u, and v are represented by mole fractions: 5.0 ≦ s ≦ 15.0 40.0 ≦ t ≦ 50.0 40.0 ≦ u ≦ 50.0 1.0 ≦ v ≦ 6.0.

When s is smaller than the above range, the relative permittivity decreases. When s is larger than the above range, Q and insulation resistance decrease. When t is smaller than the above range, the insulation resistance decreases. When t is larger than the above range, the relative permittivity decreases. If u is smaller than the above range, the insulation resistance decreases. When u is larger than the above range, the temperature coefficient of the relative dielectric constant becomes -1300 ppm / ° C. or less. When v is smaller than the above range, Q decreases. When v is larger than the above range, the temperature coefficient of the relative dielectric constant becomes −1000 ppm / ° C. or less.

In the present invention, it is preferable that 5 ≦ s ≦ 14 41 ≦ t ≦ 47 41 ≦ u ≦ 49 1.2 ≦ v ≦ 5.5.
Relative permittivity is 30 or more, Q is 150 or more, insulation resistance is 1 ×
At 10 ¹³ Ω · cm or more, −500 to +1800 ppm /
High performance dielectrics having a temperature coefficient of dielectric constant in the range of ° C. are provided.

In the present invention, it is particularly preferable that 5 ≦ s ≦ 10 41 ≦ t ≦ 47 42 ≦ u ≦ 47 2.5 ≦ v ≦ 5.0.
Relative permittivity is 30 or more, Q is 150 or more, insulation resistance is 3 ×
In 10 ¹³ Ω · cm or more, -150~ + 1300ppm /
Higher performance dielectrics having a relative dielectric constant temperature coefficient in the range of ° C. are provided.

In order to produce such a dielectric ceramic composition of the present invention, for example, lead oxide (PbO, Pb ₂ O, Pb
O ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ ), magnesium oxide (MgO), titanium oxide (TiO, Ti ₂ O ₃ , TiO)
₂ ) Powder of niobium pentoxide (Nb ₂ O ₅ ) is weighed so as to have a predetermined ratio, and thoroughly mixed using a wet ball mill or the like. Next, after drying this mixture, if necessary,
It is calcined for several hours at a temperature in the range of 1000 to 1050 ° C. The obtained calcined product is pulverized by a wet ball mill or the like. After drying the calcined powder obtained by the pulverization, an appropriate organic binder such as polyvinyl alcohol is added to form granules, and the granules are pressed into a predetermined shape and then fired. This firing is
This is performed in a temperature range of 1150 to 1250 ° C. for about 0.5 to several hours. (Of course, these manufacturing conditions are the most suitable numerical values, and the porcelain composition of the present invention may be manufactured by conditions or methods other than the above.)

[0019]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to the following examples unless it exceeds the gist.

Examples 1 to 7, Comparative Examples 1 to 5 PbO, MgO, TiO ₂ and Nb ₂ O as starting materials
₅ using, it was weighed so that the mixing ratio shown in Table 1, and mixed for about 20 hours wet with pure water in a ball mill. Then, after dehydrating and drying this mixture, 1000 to 1
The mixture was calcined while being kept at 050 ° C. for 2 hours, wet-pulverized again in a ball mill together with pure water for about 20 hours, then dehydrated and dried.

An ethanol solution of polyvinyl butyral (binder) was added to the obtained powder, and the molding pressure was about 2 t / c.
At m ^3, it was pressed into a disk having a diameter of about 15 mm and a thickness of about 0.7 mm. After holding the molded article at about 600 ° C. for 1 hour to remove the binder, the molded article was placed on a magnesia setter for 1150 minutes.
It was baked at a temperature of １２1250 ° C. for 2 hours.

Silver electrodes were placed on both sides of the obtained sintered body at 750.
It was baked at ℃ to make a parallel plate capacitor, and its electrical characteristics were examined. Table 1 shows the measurement results of the electrical characteristics of the obtained sample.

The relative dielectric constant was measured at a measurement frequency of 1 MHz, a measurement voltage of 1.0 Vrms, and a temperature of 25 ° C. using “LF Impedance Analyzer Model 4192A” manufactured by YHP. For Q, use a “Q meter model 4342A” manufactured by YHP, measuring frequency 1 MHz, temperature 25 ° C.
Was measured. The value of the insulation resistance was measured after one minute at a temperature of 25 ° C. and an applied voltage of 100 V using “Analog IR Meter 4329A” manufactured by YHP. The temperature coefficient of the relative dielectric constant was calculated from the following formula based on the capacitor capacitance measured at 25 ° C. and 85 ° C., respectively.

[0024]

(Equation 1)

[0025]

[Table 1]

As is clear from Table 1, the dielectric ceramic composition within the scope of the present invention has a large relative dielectric constant of 30 or more,
Is 100 or more, the insulation resistance is as large as 5 × 10 ¹² Ω · cm or more, and a high-performance dielectric material having a temperature coefficient of relative permittivity in a range of −500 to +1800 ppm / ° C.

[0027]

As described above, the dielectric ceramic composition of the present invention has a large relative dielectric constant, a large Q, a large insulation resistance, and a temperature coefficient of the relative dielectric constant in the range of -500 to +1800 ppm / ° C. Can be arbitrarily controlled. Therefore, not only can the dielectric ceramic composition of the present invention be used alone, but also the CaTi
O ₃ and by combining large specific dielectric constant of 100 or more such as a SrTiO ₃ and a material having a temperature coefficient of a large negative dielectric constant, has a large specific dielectric constant and a high Q value, the dielectric constant temperature A material having a small absolute value of the coefficient can also be obtained. Thus, the parts using the composite material obtained in this way can be made much smaller than conventional products, which is effective for miniaturization of various electronic devices.

Claims (1)

[Claims] 1. PbO, MgO, TiO ₂ and Nb ₂ O
_{5. A} porcelain composition consisting of sPbO · tM
When expressed in _{gO · uTiO 2 · vNb 2 O} 5, s,
t, u, and v are molar fractions: 5.0 ≦ s ≦ 15.0 40.0 ≦ t ≦ 50.0 40.0 ≦ u ≦ 50.0 1.0 ≦ v ≦ 6.0 where s + t + u + v = A dielectric porcelain composition characterized by being in the range of 100.0.