JPS6210940B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an insulating glass that is crystallized by heat treatment and a composition obtained by mixing this glass powder with a refractory filler, which is preferably used mainly for forming an electrical insulating layer for a crossover of a thick film integrated circuit. The present invention relates to a composition in which: When producing various electrical circuits such as thick film circuits by printing resistors and conductors on substrates such as alumina, glass compositions are used as electrical insulating layers or crossovers. These glass layers are effective not only as electrical insulating layers but also for protecting conductors and resistors from the surrounding environment, and are often used for the purpose of so-called cover coats. In manufacturing standard thick film integrated circuits, a conductor paste is printed and fired on a ceramic substrate mainly made of alumina, then a dielectric glass paste for crossover is printed and fired, and then a resistor paste is printed. After firing, a glass coating film is printed and fired to protect the resistor or conductor. In the case of multilayer wiring, the above steps are repeated multiple times. Conventionally, dielectric glasses used as crossovers in the production of circuits that require two or more high-temperature firings have been used to achieve high-temperature stability.
A type of crystalline glass that is crystallized by firing at ℃ is used. (For example, Special Publication No. 46-42917: 51-6168; 51-
No. 10844; see No. 52-34645). However, from the viewpoint of energy saving and to suppress deterioration of the electrical characteristics of the circuit during firing, a crossover layer with excellent electrical properties, especially electrical resistance, dielectric constant, and dielectric loss, is created by firing at a lower temperature. There is a need to develop glass powder compositions that can be formed. The present inventor has discovered that _SiO2 - _{Al2O3 -} CaO-ZnO- _TiO2
It has been found that -B ₂ O ₃ -based glass having a specific composition range satisfies the above requirements. In the present invention, in weight%, SiO ₂ 20-45% Al ₂ O ₃ 5-25 CaO 5-25 ZnO 15.5-30 TiO ₂ 5-20 B ₂ O ₃ 1-8 BaO 0-10 SrO 0-10 The present invention relates to an insulating glass composition having a composition of Sb ₂ O ₃ 0-3 SnO ₂ 0-3 Bi ₂ O ₃ 0-3 and crystallized by heat treatment at a temperature not exceeding 850°C. Furthermore, in a more preferred embodiment of the present invention,
An insulating material containing a filler made by mixing glass powder having the above composition with at least 15% by weight of at least one refractory filler powder selected from the group consisting of alumina, zircon, cordierite, zirconia, and beryllia. A glass composition is provided. The reason for limiting the composition of glass will be explained. SiO ₂ is a network former of glass, and is an anorthite (CaO,
Al ₂ O ₃ 2SiO ₂ ) It is a component that makes up the crystal. SiO ₂ ＜
At 20%, the softening point of the glass becomes too low, causing the glass to soften and flow too much before crystallizing during heat treatment.
When SiO ₂ >45%, vitrification is difficult and a high heat treatment temperature exceeding 900° C. is required for crystallization. Al ₂ O ₃ is also an essential component constituting the precipitated anorthite crystals. When Al ₂ O ₃ <5%, it is difficult to precipitate anorsite. If Al ₂ O ₃ >25%, the glass will devitrify when melted. CaO is also an essential component constituting anorsite, and when CaO<5%, it is difficult to precipitate anorsite. If CaO>25℃, the glass will devitrify when melted. In addition, the glass transition point and crystal precipitation temperature become too high, making it difficult to crystallize the glass by heat treatment at 850°C or lower. ZnO acts as a flux for vitrification. When ZnO<15.5%, the transition point of the glass becomes too high and vitrification becomes difficult. When ZnO>30%, the softening point of the glass becomes too low, causing softening flow before crystallization during heat treatment, making it difficult to bake and form an insulating coating layer of a fine pattern. _TiO2 is included to control crystallization. When TiO ₂ is less than 5%, the heat treatment temperature for crystallization becomes too high. _TiO2 ＞20%
In this case, the effect of crystallization control becomes weaker, which is not preferable. B ₂ O ₃ is used as a flux when melting glass. When B ₂ O ₃ <1%, the solubility of the glass deteriorates. When B ₂ O ₃ >8%, the softening point of the glass becomes too low, and the glass softens and flows before crystallization during heat treatment. More preferable composition ranges of the above essential components are as follows: SiO ₂ 25-45% Al ₂ O ₃ 10-20 CaO 10-20 ZnO 20-27 TiO ₂ 8-15 B ₂ O ₃ 2-5 BaO and SrO are Although none of these are essential components, the solubility of glass can be improved by introducing up to 10%, preferably up to 8%. but,
When BaO>10%, the thermal expansion coefficient of the glass becomes too high. On the other hand, when SrO>10%, the heat treatment temperature for crystallization becomes too high. Sb ₂ O ₃ , SnO ₂ and Bi ₂ O ₃ are added at 3% to improve the solubility of glass or the water resistance of glass.
The content is preferably 2% or less. In preparing the glass having the above composition, according to the conventional method, the raw materials for each component are weighed and mixed to obtain the target composition, and batches are prepared.
Heat at 1500°C for 1 to 3 hours to melt and vitrify the batch. The molten glass is pulverized or formed into flakes, and the glass pieces are pulverized using a ball mill or the like to obtain glass powder with an average particle size of 1 to 5 μm, which is used for thick film circuit coating. In a more preferred embodiment of the invention, the glass powder is mixed with up to 15% of a refractory filler powder to promote crystallization during heat treatment of the composition comprising the glass powder and the refractory filler. This can provide effects such as suppressing fluidity due to residual glass after crystallization or reducing reactivity at the contact interface between a conductor or resistor of a thick film circuit and a crossover layer. As fillers, alumina (α-alumina), zircon, cordierite, zirconia, especially stabilized zirconia, and beryllia are used. A filler content exceeding 15% is undesirable because it reduces the adhesion of the thick film circuit to the alumina substrate. Among fillers, alumina and beryllia are substances with high thermal conductivity, and when these are used as fillers, high thermal conductivity of the crossover layer can be expected. In particular, as thick film circuits become more highly integrated, a cross-over glass insulating layer with high heat dissipation properties is inevitably required, and in this sense it is preferable to use alumina or beryllia. When mixing the filler with glass powder, it is preferable to mix it into a pulverizer such as a ball mill when pulverizing the glass. Incidentally, when crushing the glass and/or mixing the filler, either a dry method or a wet method may be used, but when used for screen printing on thick film circuits, the top size of the glass and filler particles should be smaller. Preferably, the average particle size is also preferably 1 to 2 μm. In order to obtain such a finely ground powder, it is desirable to use a wet grinder. When using the composition of the present invention, it is made into a slurry or paste form and subjected to coating or printing in order to temporarily bond it to an object to be adhered, such as a thick film circuit. As the binder, well-known vehicle agents such as ethyl cellulose and α-terpineol, nitrocellulose and isoamyl acetate, butyl carbitol acetate, or pure water can be used, but are not particularly limited. After applying or printing the powder composition paste or slurry, the vehicle is evaporated by heat treatment at about 150° C. for 15 minutes or less, and then the temperature is raised to the firing temperature at a rate of 10 to 50° C./min. For firing heat treatment,
By holding the glass powder at 800 to 950°C, preferably 800 to 850°C for 5 to 15 minutes, the glass powder softens and flows to form a dense film and then crystallizes. The composition according to the present invention is suitably used for forming a crossover insulating layer of a thick film circuit, and can be printed in multiple layers alternately with a conductor paste and fired simultaneously with the upper and lower conductor layers. Even with simultaneous firing, there are no problems such as peeling of the conductor or electrical short circuit between the upper and lower conductor layers. The reason why it is possible to form a multilayer crossover layer with this composition is because the surface smoothness of the insulating film after firing is excellent. In addition, the thermal expansion coefficient after firing is 55 to 70 × 10 ^-7 °C
^-1 (50~350℃), suitable for alumina circuit boards. Regarding electrical properties, both dielectric constant and dielectric loss are small.

[Table] Glass having the composition shown in the upper row of Table 1 was melted, cooled, and then finely ground to an average particle size of 2 μm. At that time, for Samples 3, 4, and 5, alumina was mixed in the amount shown in the middle row of the table when the glass was pulverized. in this case,
The amount of glass powder in the sample composition is the remaining amount of filler. DTA characteristics Place 1.0 g of powder of each sample in the holder of a differential thermal analyzer, raise the temperature from room temperature at a heating rate of 10°C/min, draw a thermal analysis curve, and find the first endothermic onset temperature that appears on the curve. It is shown in the table as the transition point (°C). Two peaks indicating glass crystallization are shown in the table as the first and second crystallization heat temperatures. Characteristics of fired products (1) Coefficient of thermal expansion After compression molding each powder test into a rod shape, 850℃
Coefficient of thermal expansion (50 to 350) after heating for 10 minutes at
°C average) was measured and shown in the table. (2) Dielectric constant (ε), dielectric loss (tanδ) of each sample fired product (850℃, 10 minutes) at 25℃,
Measure the dielectric constant and dielectric loss at 1MHZ,
Shown in the table. Dielectric constant is 9 or less, dielectric loss is 2×
It is desirable that it be 10 ^-3 or less. (3) Volume resistivity ρ (ohm.cm) The volume resistivity of each sample fired product (850°C, 10 minutes) at 150°C was measured and shown in the table. This value is required to be greater than or equal to 10 ¹⁴ ohm.cm. (4) Acid resistance The fired product (850℃, 10 minutes) of each sample was 20%
The sample was placed in an aqueous oxalic acid solution and heated to 90°C for 10 minutes, and the weight loss rate (%) of the sample was measured, and the values are shown in the table. This value is preferably 0.3% or less. It has been found that the fired product of the glass composition according to the present invention has excellent properties such as the rate of change in resistance value of the external resistor, surface roughness, solderability, and thermal conductivity as described above.

Claims (1)

[Claims] 1 In weight%, SiO ₂ 20-45% Al ₂ O ₃ 5-25 CaO 5-25 ZnO 15.5-30 TiO ₂ 5-20 B ₂ O ₃ 1-8 BaO 0-10 SrO An insulating glass having a composition of 0 to 10 Sb ₂ O ₃ 0 to 3 SnO ₂ 0 to 3 Bi ₂ O ₃ 0 to 3, and which precipitates anorthite crystals as the main crystals by heat treatment at a temperature not exceeding 850°C. Composition. 2. Claim 1 having the following composition in weight%: SiO ₂ 25-45% Al ₂ O ₃ 10-20 CaO 10-20 ZnO 20-27 TiO ₂ 8-15 B ₂ O ₃ 2-5 The insulating glass composition described. 3 In weight%, SiO ₂ 20-45% Al ₂ O ₃ 5-25 CaO 5-25 ZnO 15.5-30 TiO ₂ 5-20 B ₂ O ₃ 1-8 BaO 0-10 SrO 0-10 Sb ₂ O The glass powder has a composition of ₃ 0-3 SnO ₂ 0-3 Bi ₂ O ₃ 0-3 and precipitates anorsite crystals as the main crystals by heat treatment at a temperature not exceeding 850°C, and contains alumina, zircon, cordierite, An insulating glass composition containing a filler formed by mixing at least one refractory filler powder selected from the group consisting of zirconia and beryllia at a weight ratio of 15% or less. 4 The glass powder has a composition in weight percent of SiO ₂ 25-45% Al ₂ O ₃ 10-20 CaO 10-20 ZnO 20-27 TiO ₂ 8-15 B ₂ O ₃ 2-5, and 4. The insulating glass composition containing a filler as claimed in claim 3, wherein the filler is alumina powder, and is mixed in a weight ratio of 90 to 99% glass powder and 1 to 10 parts alumina powder.