JP3413817B2 - Crystalline glass composition for coating - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystalline glass composition for coating, and more particularly to a crystal for coating used for coating a thick film circuit using a ferrite material. The present invention relates to a functional glass composition. 2. Description of the Related Art Various electronic components have been miniaturized and integrated with the progress of thick film technology. In particular, power supply components such as inductors and transformers, which have been considered difficult to miniaturize, and noise filters, etc., have recently been reduced in size by using a thick-film circuit with a structure in which ferrite materials and conductors are alternately stacked. Realizing. When these parts are manufactured by using the thick film technology, it is necessary to protect the circuit from the outside electrically, chemically and mechanically. Therefore, a glass for coating capable of protecting the surface is required. Required. [0004] The glass for coating has a thermal expansion coefficient (90 to 100 × 10) of a ferrite material.
^-7 / ° C), at 30 to 700 ° C
Characteristics such as a relatively high coefficient of thermal expansion of about 5 to 105 × 10 ⁻⁷ / ° C., heat resistance, and electrical insulation are required. However, since a conventional thick film circuit is formed on an alumina substrate, the coating glass for protecting the circuit has a thermal expansion coefficient of 70 to 80 × 10
^-7 / ° C). Therefore, when the conventional glass for coating is used for coating the above-mentioned ferrite material, stress is generated due to mismatch of thermal expansion coefficients, and problems such as cracks and peeling are liable to occur, which is not preferable. On the other hand, as coating glass having high expansion, MgO is disclosed in JP-B 1-48210 and JP-A-4-82294.
-B ₂ O ₃ -SiO ₂ system steel plate covering crystalline glass is disclosed. Each of these glasses does not contain an alkali metal oxide and has good heat resistance and electrical insulation properties, but has a high coefficient of thermal expansion of 110 × 10 ⁻⁷ / ° C. or more. In this case, there is a problem that countless cracks are generated in the glass coating after firing due to the difference in thermal expansion from the ferrite material. An object of the present invention is to provide a crystalline glass composition for coating which satisfies various conditions required for a glass for coating a thick film circuit using a ferrite material and which exhibits a thermal expansion coefficient particularly suitable for the ferrite material. To provide. [0008] The present inventors have SUMMARY OF THE INVENTION As a result of various experiments, the alkali-free glass of the MgO-B ₂ O ₃ -SiO ₂ system, the for Al ₂ O ₃ glass component constant The present inventors have found that the above objects can be achieved by including them in an amount, and propose the present invention. That is, the crystalline glass composition for coating according to the present invention comprises 80 to 100 parts by weight of glass powder and 0 to 100 parts by weight of filler powder.
20 parts by weight, and the glass powder is in weight percentage
_{MgO 35~45%, B 2 O 3} 18~28%, SiO
_{2 9~17%, Al 2 O 3} 3~20%, BaO 0~9
%, Other components 0-4%, essentially alkali
Contains no metal oxides.
Crystal and / or magnesium aluminosilicate
It has the property of precipitating crystals . When the crystalline glass composition for coating of the present invention is fired, magnesium borate crystals, magnesium aluminosilicate crystals, etc. are precipitated, and a heat of about 85 to 105 × 10 ⁻⁷ / ° C. suitable for ferrite material. Indicates the expansion coefficient. In addition, since the glass component hardly remains after firing, it has high heat resistance and does not flow even if heat treatment is performed again.
Moreover, since it does not contain an alkali metal oxide and is a dense fired body, it has excellent electrical insulation properties. The reasons for limiting the composition of the glass powder in the coating crystalline glass composition of the present invention as described above will be described below. When the content of MgO is less than 35%, the crystallization of the glass does not proceed sufficiently, and the heat resistance deteriorates. When the content exceeds 45%, the solubility deteriorates and it becomes difficult to obtain a homogeneous glass. When the content of B ₂ O ₃ is less than 18%, the solubility deteriorates, and when it exceeds 28%, the heat resistance deteriorates. If the content of SiO ₂ is less than 9%, the heat resistance is inferior, and at the same time, the stability of the glass during melting is deteriorated. In the present invention, Al ₂ O ₃ is a component that has an effect of lowering the coefficient of thermal expansion, improves the fluidity at the time of firing, and allows an effective amount of filler powder to be introduced. A
If l ₂ O ₃ is less than 3%, the coefficient of thermal expansion becomes too high, the difference in thermal expansion from the ferrite material becomes large, and cracks occur after firing. In addition, when the filler powder is added, the fluidity becomes poor, and a dense glass surface cannot be obtained, which is not preferable. On the other hand, if it exceeds 20%, the melting property of the glass deteriorates, and the devitrification becomes strong, which makes molding difficult. If the content of BaO exceeds 9%, the glass becomes unstable and the devitrification during molding becomes extremely strong. In addition to the above components, SnO ₂ , P ₂
Other components such as O ₅ may be added in a total amount of 4 % or less. However, the addition of alkali metal oxides that deteriorate electrical insulation must be avoided. Further, the crystalline glass composition for coating of the present invention is made of zirconia (ZrO) for fine adjustment of the coefficient of thermal expansion.
₂ ), alumina (Al ₂ O ₃ ), zircon (ZrO _2.
20 parts by weight or less of a filler powder such as SiO ₂ ) may be contained. The reason for limiting the proportion of the filler powder in this manner is that if the filler powder exceeds 20 parts by weight, that is, if the glass powder is less than 80 parts by weight, a dense fired glass surface cannot be obtained, which is not preferable. It is desirable to use filler powder having an average particle size of 1 to 5 μm. Next, a method for coating a thick film circuit using the crystalline glass composition for coating of the present invention will be described. First, a glass raw material prepared to have the above composition is melted at 1400 to 1500 ° C. for 0.5 to 2 hours. Next, after the molten glass is formed into a film or the like, it is pulverized and classified to produce a glass powder. The average particle size of the glass powder is preferably about 2 to 5 μm. Further, if necessary, a filler powder is added to the above glass powder and mixed. Next, glass powder or a mixed powder of glass powder and filler powder is mixed with an organic vehicle to form a paste, which is uniformly applied on a thick film circuit by a screen printing method. The organic vehicle used is not particularly limited. For example, an organic vehicle obtained by dissolving an ethylcellulose resin, an acrylic resin or the like in a solvent such as terpineol or butyl carbitol acetate can be used. Thereafter, by firing at 800 to 900 ° C., the glass powder softens and flows, uniformly covering the circuit surface, and at the same time depositing a large amount of crystals. In this way, a glass coating can be applied on the thick film circuit. EXAMPLES The crystalline glass composition for coating of the present invention will be described below with reference to examples. (Example 1) Tables 1 and 2 show Examples (Sample Nos. 1 to 8) and Comparative Examples (Sample No. 9) of the present invention. [Table 1] [Table 2] Each sample was prepared as follows. The glass raw materials prepared to have the compositions shown in the table were melted at 1500 ° C. for about 2 hours, and then formed into a film by passing between a pair of rollers. Next, the obtained film-shaped molded product is pulverized using a ball mill and classified,
A glass powder having an average particle size of 3 μm was obtained. 1 to 6 and 9. Sample No. Sample No. 6 was prepared by adding alumina powder or zircon powder having an average particle size of 2 μm to the glass powder of Sample No. 6. 7 and 8. The sample thus obtained was measured for the coefficient of thermal expansion. Each sample was kneaded with a terpineol solution of ethylcellulose to give a viscosity of 1500 ps. A degree of paste was obtained. This paste has a coefficient of thermal expansion of 97 ×
Print on the surface of Mn-Zn ferrite plate of 10 ^-7 / ° C.
After drying the solvent at 00 to 150 ° C.,
Baking was performed at 50 ° C. for 10 minutes to form a glass coating having a thickness of 15 to 20 μm. Subsequently, using the fired product, the presence or absence of cracks in the glass coating and the heat resistance were evaluated. These results are shown in each table. As is clear from Tables 1 and 2, the sample No. 1 to 8 have a coefficient of thermal expansion of 9
The temperature was 5.5 to 104.0 × 10 ⁻⁷ / ° C., and no cracks were observed when the ferrite plate was coated. It was also found that the heat resistance was good. On the other hand, the sample No. Sample No. 9, which had good heat resistance, had a high thermal expansion coefficient of 112 × 10 ⁻⁷ / ° C. because it did not contain alumina, and countless cracks were observed. The thermal expansion coefficient was calculated from a thermal expansion curve measured by a dilatometer after a sample was press-molded into a rod shape and fired at 850 ° C. Heat resistance was determined by repeating the cycle of heating the glass-coated ferrite sheet from room temperature to 850 ° C. five times, and then observing changes in the shape of the glass coating and cracks. Good and those which were recognized were regarded as bad. As described above, the crystalline glass composition for coating of the present invention satisfies the required conditions and exhibits a thermal expansion coefficient particularly suitable for ferrite materials. It is suitable for coating a thick-film circuit using the same.

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C03C 1/00-14/00 C04B 41/80-41/91 WPI

Claims (1)

(57) [Claim 1] 80 to 100 parts by weight of glass powder,
From 0 to 20 parts by weight of the glass powder,
35 to 45% MgO by weight percent, B ₂ O ₃ 18~2
_{8%, SiO 2 9~17%,} Al 2 O 3 3~20%, B
consisting of 0-9% of aO and 0-4% of other components
It does not contain alkali metal oxides,
Cium borate crystal and / or magnesium alumino
Characterized by the ability to precipitate silicate crystals
Crystalline glass composition for coating.