JPS6111403B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to low loss dielectric compositions. Specifically, the present invention relates to a dielectric composition that can be fired at a temperature of about 800 to 1000° C. and that can yield a capacitor with small dielectric loss. Capacitors are one of the most commonly used electrical components in electrical circuits, and their electrical characteristics vary depending on the type of material and composition ratio. Therefore, the types of materials and composition ratios are generally determined depending on the intended use. The electrical characteristics of a capacitor include capacitance, dielectric loss, insulation resistance, etc. In porcelain dielectrics, insulation resistance is generally large, so it does not matter much, but capacitance and dielectric loss become a problem. In particular, dielectric loss is a major factor in capacitors used in high frequency ranges.If the dielectric loss is large, the capacitor itself will generate heat, and if it exceeds a certain limit, the capacitance will change significantly, and the circuit will not function as designed. It disappears. In recent years, with the miniaturization of circuits, there has been a demand for smaller components, and the hybrid integrated circuit (hereinafter referred to as HIC) has been devised as the most advanced form. HIC is a device in which a conductor, a resistor, and a capacitor are formed in a predetermined shape on a ceramic substrate such as alumina.
to dig out. In general, materials for conductors, resistors, or capacitors are powdered, dispersed and kneaded in a suitable vehicle, and then applied as a paste by screen printing, etc., and then baked at a temperature of about 800 to 1000°C to form a circuit. Form. Traditionally, materials for capacitors used in such applications include:
A mixture of dielectric ceramic powder such as BaTiO ₃ or TiO ₂ with glass powder, or only glass powder has been proposed. however,
Products using dielectric ceramic powder such as BaTiO ₃ and TiO ₂ have a high dielectric constant but large dielectric loss, and those using only glass powder have a small dielectric loss but have a too low permittivity. There were many difficulties.
In HIC, to compensate for this drawback, small porcelain capacitors manufactured with a special composition are connected with solder, etc., but the main parts of such capacitors are usually made of porcelain sintered at 1,300 to 1,400 degrees Celsius. It is expensive because it is a dielectric material and the manufacturing process for small products is complicated. Thus, after being applied in paste form to a porcelain substrate such as alumina, the
There is a strong demand for the development of capacitor materials that can be fired at 1000℃. The purpose of the present invention is to respond to such demands,
A new low-loss dielectric that can be fired at temperatures of about 800 to 1000℃, yields a dense capacitor layer without cavities, and allows adjustment of the dielectric constant while maintaining a low dielectric loss. An object of the present invention is to provide a composition. In order to achieve this objective, the inventor of the present application, as a result of intensive research, found that 100 parts by weight of barium titanate porcelain powder consisting of 90% by weight or more of Ba ₄ Ti ₁₃ O ₃₀ , 10% by weight or less of BaO, and 5% by weight or less of TiO ₂ and glass. quality binder 4~
It was discovered that the dielectric composition was mixed with 20 parts by weight, fired at a temperature of 650 to 750°C, cooled and crushed, and that the dielectric loss of the capacitor used as the material was extremely small compared to conventional compositions in the high frequency range. We have arrived at the present invention. Barium titanate porcelain powder is BaO or _BaCO3
It is produced by high temperature reaction with TiO ₂ and the use of BaCO ₃ is preferred to obtain it in powder form. of the main component
Ba ₄ Ti ₁₃ O ₃₀ is a compound with a molar ratio of BaO and TiO ₂ of 4:13 and has an orthorhombic crystal structure. Ba ₄ Ti ₁₃ O ₃₀
It is desirable _for the content of
Ba ₄ Ti ₁₃ O ₃₀ 90% by weight or more, BaO 10% by weight or less
A preferred range of TiO ₂ is 5% by weight or less. If TiO ₂ is contained at 5% by weight or more, TiO ₂ will be added to the capacitor.
This is not desirable because the influence of Also BaO
If the content exceeds 10% by weight, the influence of BaO becomes significant and it becomes unusable. It is necessary to add a vitreous binder to bond the barium titanate porcelain powder to form a dielectric layer and at the same time to fix it to an alumina substrate or the like. The amount of the vitreous binder added is most preferably such that it sufficiently fills the interparticle gaps of the barium titanate porcelain powder, and is suitably 4 to 20 parts by weight per 100 parts by weight of the barium titanate porcelain powder. If it is less than 4% by weight, minute cavities will be created in the dielectric layer, causing pinholes and deteriorating the electrical characteristics;
If this is the case, the particles will flow out of the dielectric layer and the predetermined shape cannot be maintained. The addition ratio of the vitreous binder is adjusted within the above range depending on the particle size of the barium titanate porcelain powder and the type of vitreous binder used. After thoroughly mixing barium titanate porcelain powder and a glassy binder in the above ratio, firing at a temperature of 650 to 750°C to melt or semi-molten the glass, barium titanate is added to the molten or semi-molten glass. The porcelain powder is uniformly dispersed, rapidly cooled in post-cooling water, and pulverized to produce a dielectric composition. By the heat treatment of firing and rapid cooling described above, the barium titanate porcelain powder and the vitreous binder are well integrated and a dense dielectric layer without pinholes can be obtained. However, if such treatment is not performed, pinholes will occur more frequently in the dielectric layer, which is not preferable. The vitreous binder used in the present invention has a melting point of approximately
It is desirable that it has good wettability with barium titanate porcelain powder at 500 to 700°C and is compatible with the linear expansion coefficient of the substrate used for HIC. Although such glasses can be manufactured arbitrarily by combining various components, the inventor of the present application has developed a method using a four-layered glass of PbO-B ₂ O ₃ -PbF ₂ -SiO _{2 .}
Considering original glass, PbO50 to 80% by weight,
_{B2O3 10-40} % by weight, _PbF2 2-15% by weight, and
It has been found that a glass containing 5% by weight or less of SiO ₂ and a total of 98% by weight or more is suitable. Note that there is no problem in use even if it does not contain SiO ₂ at all.
Further, the vitreous binder is not limited to those mentioned above, and any vitreous binder may be used as long as it satisfies the conditions of melting point, wettability, and coefficient of linear expansion. Although the dielectric composition constructed in this manner can realize the intended purpose of a capacitor with a low dielectric loss, the dielectric layer is rather brittle and the dielectric constant is limited. Therefore, in order to increase the hardness and adjust the dielectric constant, SiO ₂ ,
One or two of Al ₂ O ₃ , ZrO ₂ , MgO, ZnO, BaO
0.2 to 10 parts by weight of seeds or more, or In ₂ O ₃ , Bi ₂ O ₃ ,
0.2 to 5 parts by weight of one or more of Sb ₂ O ₃ or 1 of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , MgO, ZnO, BaO
0.1 to 10 parts by weight of a species or two or more species and In ₂ O ₃ ,
0.1 to 5 parts by weight of one or more of Bi ₂ O ₃ and Sb ₂ O ₃ are added in a total of 0.2 to 10 parts by weight. If the amount of this additive added is too small, the degree of hardening of the dielectric layer will naturally be small, and if it is too large, the electrical characteristics of the additive itself will appear, which is undesirable. The type and amount of additives to be added are selected depending on the purpose and use. Next, the present invention will be explained in more detail with reference to Examples. Example First, the molar ratio of BaCO ₃ and TiO ₂ is BaO:TiO ₂ =
They were weighed and mixed at a ratio of 1:3 and fired at about 1260°C to produce barium titanate porcelain powder. As a result of X-ray diffraction, it was confirmed that the main component of this barium titanate porcelain powder was Ba ₄ Ti ₁₃ O ₃₀ and a small amount of BaO. The vitreous binder _is 46.5% by weight _{of Pb3O4} , _H3BO3
Thoroughly mix 44.5% by weight and 9% by weight of PbF ₂ ,
The product was melted at 900°C for 30 minutes, rapidly cooled with pure water, and then wet-pulverized in a ball mill. This glass has a melting point of 550
℃, the softening point was 500℃, and the linear expansion coefficient was 98×10 ⁻⁷ /℃ in the range of 20 to 300℃. 8.2% by weight of this glass compared to 91.8% by weight of barium titanate porcelain powder
After mixing and melting at 700℃ for 30 minutes, it was rapidly cooled in pure water, wet-pulverized in a ball mill, dried, passed through a 200-mesh sieve, and the portion under the sieve was obtained as a dielectric composition, which was used as the paste base material below. provided. A paste was prepared by kneading 88% by weight of this dielectric composition with 12% by weight of a vehicle (pine oil solution containing 8% by weight of ethyl cellulose). The amount of vehicle added can be changed arbitrarily to adjust the viscosity of the paste. Dielectric composition 84.8% by weight in a similar manner
A paste was prepared by kneading 3.2% by weight of each of SiO _{2 ,} Al ₂ O ₃ , In 2 O 3 , ZrO ₂ , Bi ₂ O ₃ and BaO with 12% by weight of vehicle _. These pastes were fired as follows, and their dielectric properties were measured. It has an Ag-Pd bottom electrode fired in a 12mm diameter circular pattern with lead wires.
Each of the above dielectric pastes was screen printed in a pattern with a diameter of 14 mm, aligned with the center of the lower electrode of a 20 mm x 18 mm x 1 mm thick 96% alumina substrate. After evaporating the solvent on this substrate at 120 to 130℃, one cycle takes 45 minutes, with a peak temperature of 1000℃ and a peak retention time.
The dielectric layer was fired through a belt firing furnace with a 10 minute temperature profile. Next, a circular pattern with a diameter of 12 mm was printed on the dielectric layer with an upper electrode using Ag-Pd conductive paste with a lead line on the opposite side from the lower electrode lead line, and the peak temperature was 850℃ and the peak holding time was 10 minutes. An electrode was formed by firing in a firing furnace having a temperature profile. For these samples, the dielectric constant ε _s and dielectric loss angle tan at room temperature
δ was measured. Table 1 shows the measured values of the dielectric constant ε _s at each frequency, and Table 2 shows the measured values of the dielectric loss angle tan δ at each frequency.

【table】

[Table] For the measurement range from 1KHz to 1MHz, a broadband dielectric loss measurement device made by Ando Electric is used.
A Meguro Denpa Q meter was used between Hz. Table 1 shows that the relative dielectric constant can be adjusted depending on the type of additive, and that even if the additive is added, a substantially constant relative dielectric constant is maintained over a wide frequency range.
Table 2 also shows that the dielectric loss angle tends to increase with additives compared to those without additives, but as the frequency increases, the dielectric loss angle decreases. This shows that it is possible to reduce the value to 20×10 ^-4 or less.
Similar results were obtained when one or more of MgO, ZnO, or Sb ₂ O ₃ was added. As described above, according to the dielectric composition of the present invention, the dielectric loss of the base material is extremely small in the high frequency range, so by changing the type and amount of additives, it is possible to maintain sufficient dielectric loss to withstand use. It is possible to realize various levels of dielectric constant while maintaining the same properties. Therefore, the dielectric composition of the present invention can be applied to various uses of high-frequency equipment, such as decoupling capacitors in high-speed computers,
It can be applied to TEM wave transmission lines, distributed constant filters, directional couplers, television tuners, crossover insulation materials, etc. In the above embodiments, the dielectric composition was used in the form of a paste, but the composition is not limited to being used in the form of a paste, but can also be used, for example, as a conventional individual component. In this case, the powder is pressure-molded and then fired, and the firing temperature is similarly sufficient at about 1000°C, which is lower than the sintering temperature of conventional porcelain capacitors, making it extremely easy to manufacture. For example, when making a multilayer ceramic capacitor, in conventional ceramic capacitors, the internal electrode materials are limited to Pd, Pt, etc. that can withstand high temperatures, but with the dielectric composition of the present invention, inexpensive materials such as Ag-Pd can be used. It has the advantage that it can be used to reduce overall product costs.

Claims (1)

[Claims] 1 100 parts by weight of barium titanate porcelain powder consisting of 90% by weight or more of Ba ₄ Ti ₁₃ O ₃₀ , 10% by weight or less of BaO, and 5% by weight or less of TiO ₂ forms a vitreous bond of 4 to 20 parts by weight. A low-loss dielectric composition that is uniformly dispersed in an agent. 2 100 parts by weight of barium titanate porcelain powder consisting of at least 90% by weight of Ba ₄ Ti ₁₃ O ₃₀ , not more than 10% by weight of BaO, and not more than 5% by weight of TiO ₂ is uniformly dispersed in 4 to 20 parts by weight of a vitreous binder. SiO ₂ , Al ₂ O ₃ ,
A total of 0.2 to 10 parts by weight of one or more of NrO ₂ , MgO, ZnO, BaO, or In ₂ O ₃ ,
Bi ₂ O ₃ , Sb ₂ O ₃ , one or more types in total
0.2 to 5 parts by weight, or SiO ₂ , Al ₂ O ₃ , ZrO ₂ ,
A total of one or more of MgO, ZnO, and BaO
0.1 to 9.9 parts by weight and a total of 0.1 to 5 parts by weight of one or more of In ₂ O ₃ , Bi ₂ O ₃ , and Sb ₂ O ₃ in a total of 0.2 to 10 parts by weight. Lossy dielectric composition. 3 The vitreous binder contains 50 to 80% by weight of PbO,
2. The low loss dielectric composition according to claim _{1 or} 2, comprising 10 to 40% by weight of B2O3 and 2 to 15% by weight of _PbF2 , the total of which is 98% by weight or more. 4 The vitreous binder contains 50 to 80% by weight of PbO,
_{B2O3 10-40} % by weight, _PbF2 2-15% by weight and
2. The low loss dielectric composition according to item 1 or 2, which contains 0.1 to 5% by weight of SiO ₂ , the total of which is 98% by weight or more.