JPH0239463B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention particularly relates to an enamel frit suitable for manufacturing composites of metals and high dielectric constant materials.
More specifically, the present invention mainly relates to an enamel frit that is adhered to a metal plate such as a steel plate or a stainless steel plate and is fired to form a high dielectric constant material that adheres well to the metal plate. BACKGROUND ART In recent years, composites of high-permittivity materials and metals have been attracting attention and being developed as high-permittivity materials for use in electronic components, discharge electrode parts, etc., with the aim of improving heat resistance, mechanical strength, and cooling performance. Conventionally, titanate ceramics have been mainly used as the above-mentioned high dielectric constant material, but in order to composite the above-mentioned titanate ceramics and metals, bonding methods using synthetic resin adhesives, Ag, Ag-Pd, etc. There is a method in which a noble metal paste such as the above is applied to the titanate ceramic and soldered to the metal after baking. However, the former has the drawbacks of poor heat resistance and unsatisfactory interlayer adhesion strength, while the latter has the drawbacks that the noble metal paste is expensive and involves many complicated steps. As the above-mentioned high dielectric constant material, research is also being conducted on glasses containing BaTiO ₃ crystals with a high dielectric constant (for example, Journal of American
Ceramic Society, Vol. 47, No. 3, 1964), the above-mentioned glasses have poor affinity with metals, and there is a practical problem in making them into composites with metals. In other words, the above-mentioned glass does not match metal plates such as steel plates and stainless steel plates in terms of thermal expansion characteristics and softening and melting temperatures.
It had no adhesion to these metal plates and could not be practically used in the production of the above-mentioned composites. SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned conventional drawbacks and to provide an enamel frit that forms a high dielectric constant material having good adhesion to a metal plate. And the above purpose contains a metal oxide consisting of BaO and/or SrO and TiO ₂ in a total amount of 10 to 60% by weight,
and the molar ratio of the metal oxide and TiO ₂ is 0.5 to 1.5.
This is achieved by the enamel frit of the present invention, which precipitates crystals with a high dielectric constant by being heat-treated. It is further preferable that the enamel frit has a body thermal expansion coefficient.
200 to 330×10 ^-7 (/°C), and has a softening and melting temperature of 500 to 700°C, and substantially does not contain high dielectric constant crystals before heat treatment,
For this purpose, the total amount of the above metal oxide and TiO ₂ must be 25
~55% by weight, the molar ratio of the above metal oxide and _TiO2 is 0.9-1.4, or the above metal oxide and
Glass components other than TiO ₂ are SiO ₂ 15 to 45% by weight,
_B2O3 10-30% _by weight, _{Al2O3 10} % by weight or less,
10% by weight or less of one or more metal oxides selected from the group consisting of Na ₂ O, K ₂ O and Li ₂ O;
It is preferable that the material contains 4 to 25% by weight of one or more metal oxides selected from the group consisting of CaO, ZnO, MgO and Sb ₂ O ₃ and 10% by weight or less of F. The present invention will be explained in detail below. An example of manufacturing the enamel frit of the present invention having the above composition will be described below. A metal oxide consisting of BaO and/or SrO (hereinafter referred to as MO) and a metal compound such as a metal oxide, metal hydroxide, or metal salt that donates TiO ₂ are mixed at the above molar ratio, that is, MO/TiO ₂ 0.5~
1.5, preferably 0.9 to 1.4, or a calcined product of MO and TiO ₂ with the above molar ratio, and then add other glass raw materials such as SiO ₂ and Al ₂ O ₃ over high heat. sexual raw materials such as B ₂ O ₃ ,
Low-flame raw materials such as alkali metal oxides and alkaline earth metal oxides are combined with MO and TiO ₂ in a total amount of 10 to 60.
Weight% (hereinafter simply referred to as %), preferably 25 to 55
%, and further desirably other glass raw materials are SiO ₂ 15-45%, B ₂ O ₃ 10-30%,
10% or less of Al ₂ O ₃ , 10% or less of one or more metal oxides selected from the group consisting of Na ₂ O, K ₂ O and Li ₂ O, CaO, ZnO, MgO and Sb ₂ O ₃ One or more metal oxides selected from the group consisting of 4 to 25% of metal oxide and 10% or less of F are mixed to give a glass composition, and the above mixture is heated at 1200 to 1300℃ for 50 minutes using the usual method for manufacturing glass. Heat to melt for ~60 minutes, then cool with water or air. In this way, the enamel frit of the present invention is obtained, but in this case it is desirable to cool it rapidly so that a large amount of crystals with a high dielectric constant produced from MO and TiO ₂ do not precipitate in the glass. As mentioned above, in the present invention, MO+TiO ₂
= 10 to 60%, MO/TiO ₂ = 0.5 to 1.5 molar ratio is essential, and the reason is that MO + TiO ₂ <
Enamel frit with a concentration of 10% has less precipitation of high dielectric constant crystal phase due to heat treatment, so no high dielectric constant material is formed, while MO + TiO ₂ >60
%, the enamel frit has a melting working temperature of 1400
℃ or higher, which is impractical, and the composite metal cannot withstand such high temperatures. Furthermore, a high dielectric constant material cannot be obtained outside the range of 0.5<MO/TiO ₂ <1.5. The enamel frit of the present invention, which has a body thermal expansion coefficient of 200 to 330×10 ^-7 (/℃) and a softening and melting temperature of 500 to 700℃, is compatible with general metal plates such as steel plates and stainless steel plates. A high dielectric constant material having particularly good adhesion is formed. Here, the softening melting temperature refers to the yield point when measuring the body thermal expansion coefficient. In order to provide the enamel frit of the present invention with the above-mentioned preferable body thermal expansion coefficient and softening melting temperature, the composition of the glass components other than MO and TiO ₂ is adjusted as described above. MO,
The effects of each constituent element of the glass component other than TiO ₂ and the reason for its limitation will be explained below. When SiO ₂ <15%, the material is difficult to vitrify during enameled frit manufacturing, and when SiO ₂ >45
%, the processing temperature required when applying to metal and fusing it becomes too high. When B ₂ O ₃ <10%, the above-mentioned treatment temperature similarly becomes too high, and when B ₂ O ₃ >30%, the water resistance of the resulting high dielectric constant material decreases, making it unsuitable for practical use. When Al ₂ O ₃ >10%, the treatment temperature becomes too high. When Na ₂ O + K ₂ O + Li ₂ O>10%, the concentration of alkali metal ions with high mobility increases in the resulting high dielectric constant material, and the dielectric breakdown strength decreases. When CaO+ZnO+MgO+Sb ₂ O ₃ <4%, the treatment temperature becomes too high and the body thermal expansion coefficient becomes small. Also, CaO + ZnO + MgO +
When Sb ₂ O ₃ >25%, the water resistance of the resulting high dielectric constant material decreases, making it unsuitable for practical use. When F>10%, phase separation occurs during melting by heat treatment. It goes without saying that in addition to the above-mentioned constituent elements, known compounds such as CoO and NiO may be further contained in order to improve adhesion to metals. An example of manufacturing a high dielectric constant material-metal composite using the enamel frit of the present invention will be described below. An aqueous slip is prepared by mixing the enamel frit obtained as described above with an electrolyte and an adhesive and pulverizing it in a conventional manner. The water-based slip obtained in this way is applied to a specified metal plate by a conventional method such as spraying, brush coating, flow coating, or dipping to give a coating of usually 100 to 100%.
Apply to a thickness of about 200μ and dry at room temperature or with slight heat. After that, the enamel frit is fused to the surface of the metal plate by heat treatment to a temperature higher than the softening melting temperature, and then, when appropriately cooled, high dielectric constant crystals generated from MO and TiO ₂ are precipitated, and thus the composite is formed. You can get it. In addition to the above method, the enamel frit of the present invention can be applied to a metal plate.
A method of screen printing using ink made by mixing enamel frit with squeegee oil,
A method in which enamel frit is dispersed in a suitable medium and deposited by electrophoresis, a dry method in which enamel frit powder is deposited by dry spraying, electrostatic coating, fluidized dipping, etc. may be applied. In addition, in the dry method, if the metal plate is heated in advance to a temperature higher than the softening and melting temperature of the enamel frit, the enamel frit can be fused at the same time as it is applied. The dielectric constant of the high dielectric constant material formed in the above composite can be adjusted to a predetermined value by changing the cooling rate, maintaining a predetermined temperature for a predetermined time during the cooling process, or by reheating the above-mentioned material. This can be easily achieved by controlling the amount of high dielectric constant crystals precipitated. The reason why the enamel frit of the present invention exhibits good adhesion to metal plates is not clear, but the enamel frit of the present invention hardly contains high dielectric constant crystals before heat treatment, or even if it does, it contains only a small amount. Therefore, when applied to a metal plate and subjected to heat treatment, it is thought that better wetting is achieved compared to enamel frit containing a large amount of high dielectric constant crystals. Therefore, in the enameled frit of the present invention, the high dielectric constant crystal is MO.
It is desirable that the content is 40% or less of +TiO ₂ , and of course it is most desirable that the above-mentioned high dielectric constant crystals are not included at all. Limiting the high dielectric constant crystal content in the enamel frit of the present invention as described above not only brings about good results in adhesion with metal, but also improves the dielectric constant of the high dielectric constant material by adjusting the heat treatment conditions. has the advantage of making it easier to adjust to the desired value. Examples for explaining the present invention in more detail will be described below. Example: Put the raw material mixture into a crucible and heat at 1200 to 1300℃ for 50 minutes.
The mixture was heated and melted for ~60 minutes, and the resulting melt was quenched by pouring it into water to obtain an enamel frit having the composition shown in Table 1. The enamel frit thus obtained is milled with water to prepare a slip in a conventional manner. The above slip is glazed to a thickness of about 100 to 200 μm on a mild steel plate and a stainless steel plate (50 x 50 x 1.4 mm) by a spray method. It was dried at room temperature and then heat treated at 950°C for 3 minutes. After the above heat treatment, it was cooled to 850°C, maintained at this temperature for 50 minutes, and then allowed to cool. The values of the dielectric constant of the high dielectric constant material obtained in this way, the body thermal expansion coefficient of the enamel frit, and the softening and melting temperature are
Shown in the table. In addition, in Tables 1 and 2, sample No. 1
-11 are examples of the present invention, and samples No. 12-13 are comparative examples. According to Table 2, Examples Nos. 1 to 11 of the present invention have much higher dielectric constants than Comparative Examples Nos. 12 to 13.

【table】

[Table] In addition, the dielectric constants of high dielectric constant materials obtained by heat-treating the compositions of Samples Nos. 1, 4, 6, and 9 in Table 1 in the same manner as above and cooling them at a rate of 400°C/hr are as follows: It is shown in Table 3. Table 3 also shows the data from Table 2, which was maintained at 850°C for 50 minutes.

[Table] As shown in Table 3, the dielectric constant of the high dielectric constant material made of enameled frit of the present invention can be adjusted to a wide range by changing the heat treatment conditions. Furthermore, Table 4 shows the relationship between the high dielectric constant crystal content and the adhesion to the mild steel plate after heat treatment in the composition of Sample No. 1 in Table 1.

[Table] △: Slight cracks around the periphery ×: Peeling In Table 4, the high dielectric constant crystal content is determined for the enamel frit samples in which the amount of high dielectric constant crystals precipitated was changed by various heat treatment conditions. The adhesion was calculated from the line diffraction peak intensity, and the adhesion was evaluated for composites obtained by applying enamel frits having various precipitated amounts of high dielectric constant crystals to mild steel plates and subjecting them to a certain heat treatment. Looking at Table 4, it is clear that when the high dielectric constant crystal content of the enamel frit of the present invention is 40% or less, the adhesion is good, but when it exceeds 40%, the adhesion is reduced. As described above, the enamel frit of the present invention has good adhesion to metals and forms a high dielectric constant material, so it is extremely useful in the electronic industry.

Claims (1)

[Claims] 1 A metal oxide comprising BaO and/or SrO and TiO ₂ in a total amount of 10 to 60% by weight, and a molar ratio of the metal oxide to TiO ₂ of 0.5 to 1.5. 1. Enamel frit, which is a glass within the above range, and is characterized by precipitating crystals with a high dielectric constant by being heat-treated. 2. The enamel frit according to claim 1, which has a thermal expansion coefficient of 200 to 330×10 ^-7 (/°C) and a softening and melting temperature of 500 to 700°C. 3. The enamel frit according to claim 1, which does not substantially contain high dielectric constant crystals before heat treatment. 4 The total amount of the metal oxide and TiO ₂ is 25 to 55% by weight, and the molar ratio of the metal oxide to TiO ₂ is 0.9 to 1.4.
The enamel frit according to claim 1. 5 _SiO2 15-45% by weight, _{B2O3 10-30} % by weight,
Al ₂ O ₃ 10% by weight or less, 10% by weight or less of one or more metal oxides selected from the group consisting of Na ₂ O, K ₂ O and Li ₂ O, CaO, ZnO, MgO and
Claim ₂ , which contains a glass component consisting of 4 to 25% by weight of one or more metal oxides selected from the group consisting of Sb 2 O ₃ and 10% by weight or less of F;
Enamel frit according to item 3 or 4.