JPH0452561B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition for forming an insulating layer used in thick film circuit components, particularly multilayer circuits provided on a substrate. Thick-film circuit components, in which circuits are formed by printing paste on an insulating substrate and baking it, have gone from forming a single layer of circuits on a substrate to achieve higher density, to forming circuits in multiple layers via an insulating layer in recent years. There is a need for so-called multilayer circuit components. Insulating layers used in such circuit components include:
It is easy to form, its formation causes little change in the resistance value of the low antibody in the circuit, it does not worsen the solder wettability of the conductor formed on the insulating layer, and it is heat-treated during circuit formation. Preferably, the material has characteristics such as having a coefficient of thermal expansion equal to or slightly lower than that of the substrate so as not to break the underlying circuit, and being able to be formed at a low temperature (preferably 650° C. or lower). Furthermore, it is desired to use SIC, which has excellent thermal conductivity, that is, good heat dissipation, as a substrate instead of conventional alumina. The coefficient of thermal expansion of this SIC is approximately 40×10 ^-7 /℃ and that of alumina is 70×10 ^-7 /℃.
Since it is smaller, the insulating layer needs to be correspondingly smaller. However, a glass frit having all of the above characteristics has not yet been known. The present invention was made in view of the above, and an object of the present invention is to provide a composition for an insulating layer that satisfies the above characteristics. That is, in the present invention, the glass powder is 60 to 60% by weight.
98 and a low thermal expansion filler 2 to 40 having a coefficient of thermal expansion smaller than that of the glass, and the glass powder contains ZnO 40 to 65 B ₂ O ₃ 14 to 27 SiO ₂ 4 to 20 Al ₂ O in weight percent. ₃ 2-8 SnO ₂ 0.05-2.0 Contains at least one selected from MgO, CaO, BaO and SrO, and their total amount 0.05-10 Contains at least one selected from Li ₂ Na ₂ O and K ₂ O A composition for a thick film circuit insulating layer is characterized in that the total amount thereof is 0.05 to 3. The composition according to the present invention can form a dense glass insulating layer with crystals at an extremely low temperature of 600 to 650°C, so it has good workability, and since the insulating layer is stable, the next layer and insulating layer can be formed. The heat treatment during the process does not affect the low resistance and conductors in the circuit.
Therefore, the solder wettability of the conductor formed on the insulating layer is not impaired, and the change in the resistance value of the low-voltage resistor in the circuit is extremely small. Furthermore, since the insulating layer has a coefficient of thermal expansion slightly smaller than that of SIC, clutching due to thermal stress will not occur even if printing and baking are repeated. The reasons for the limitations in the composition of the present invention are as follows. If the glass powder is >98% (therefore, the filler is <2%), the coefficient of thermal expansion will be higher than that of SIC, and cracks may occur in the glass layer due to heat treatment, while if the glass powder is <60% (therefore, the filler is >40%), the glass component will be Both are unfavorable because they are insufficient and a dense glass layer cannot be obtained. Glass powder is 65% to 95% within the above range
is more desirable. The composition of such glass powder is as follows. ZnO is a component of glass and zinc silicate crystals. When ZnO<40%, the softening temperature and crystallization temperature of the glass become too high, making it impossible to sinter at a temperature below 650°C, and when ZnO>65%, the glass shifts out of the vitrification region and is lost during melting of the glass. Both are undesirable because they generate transparency. ZnO is within the above range
A range of 45-60% is more desirable. B ₂ O ₃ acts to lower the softening temperature of glass.
When B ₂ O ₃ <14%, devitrification occurs during glass melting,
If B ₂ O ₃ >27%, it becomes difficult to form crystals in the glass layer, which is not preferable. B ₂ O ₃ is more preferably in the range of 16 to 25% of the above range. SiO ₂ is a component of glass formation and the crystals mentioned above.
If SiO ₂ <4%, devitrification will easily occur during glass melting, and if SiO >20%, the softening temperature of the glass will become too high, making it difficult to form a glass layer at low temperatures, so both are unfavorable. . More preferably, SiO ₂ is in the range of 5 to 17% within the above range. Al ₂ O ₃ is added to prevent the formation of devitrification during the glass melting process. When Al ₂ O ₃ <2%, the effect is small, and when Al ₂ O ₃ >20%, the softening temperature of the glass becomes too high and the crystallization temperature into the glass layer becomes too high, both of which are unfavorable. More preferably, Al ₂ O ₃ is in the range of 3 to 6% within the above range. SnO ₂ is added to improve the water resistance of the glass layer. If SnO ₂ <0.05%, the effect is not sufficient;
If SnO ₂ >2%, the effect is not different from that within the scope of the present invention, but the raw material cost increases, so either is not preferable. The content of SnO ₂ is preferably in the range of 0.1 to 1.5% in the above range. At least one of MgO, CaO, BaO, and SrO is added to improve the solubility of the glass and reduce the viscosity at high temperatures. Oxides MgO, CaO,
If the total amount of BaO and SrO is less than 0.05%, the effect will be small, and if the total amount of oxides MgO, CaO, BaO and SrO exceeds 10%, the coefficient of thermal expansion of the glass will be too large than that of SiC, and the glass layer will Both are undesirable as cracks may occur. The content of these oxides is more preferably 0.1 to 8% within the above range. At least one of Li ₂ O, Na ₂ O, and K ₂ O is added to improve the solubility of the glass. oxide _Li2O ,
If the total amount of Na ₂ O and K ₂ O is less than 0.05%, the effect will be small, and if it exceeds 3%, the expansion coefficient will be sic.
Both are unfavorable.
The content of these oxides is more preferably 0.1 to 2% within the above range. On the other hand, any filler may be used as long as it causes little deterioration in the solder wettability of the conductor formed on the glass layer and little change in the low resistance value of the low antibody formed in the circuit. Quartz glass, silicate glass, cordierite, β-eucliptite, and β-sposiwomene, which have such characteristics and are relatively inexpensive, are particularly suitable as fillers in the present invention. Such fillers are added to the glass powder alone or in combination. The composition in the present invention is manufactured, for example, as follows. Each raw material is weighed using a conventional method to achieve the target composition and thoroughly mixed. Next, this is heated and melted to form a glass plate by a roll-out method or the like. Next, this glass plate is made into a powder frame to produce powder glass. The composition of the present invention is then produced by adding a powdered filler to this glass powder. When such a composition is used to form an insulating layer of glass, a suitable vehicle is added to the composition to form a paste. Example After each raw material was weighed and mixed so as to have the composition shown in Table 1, it was heated and dissolved at 1300 to 1450° C. with stirring for 1 to 2 hours. Next, the obtained glass was soaked in water to obtain a glass powder having an average particle size of 2 μm and a maximum particle size of 45 μm. A filler having an average particle diameter of 2 μm was added to this glass powder (the type of filler and the amount added thereof are listed in the weight percentage of the filler in the composition) and mixed. A vehicle consisting of 95% α-terpineol and 5% ethylcellulose was then added to the above mixture.
A paste was prepared by adding 35g to 100g and kneading.
Next, the paste was printed so as to cover the first Ag--Pd conductor, which had been previously formed by printing and firing on an alumina substrate, and the RuO ₂ low antibody formed between the conductors. This was then fired at a temperature of 600 to 650° C. for 10 minutes to form a glass layer as an insulating layer with a thickness of about 40 μm on the conductor and the low antibody. Next, a second Ag--Pd conductor was formed on the glass layer by a conventional method. Regarding the glass layer formed in this way, the insulation resistance value, positive dielectric theory and permittivity of the glass layer, and the second Ag
- The results of measuring the solder wettability of the Pd conductor, that is, the upper conductor, and the resistance change rate of the low antibody are also listed in Table 1. In addition, the glass transition point, softening point, and crystal peak point in the same table are the results measured using a differential thermal analyzer for each glass, and the expansion coefficient is measured separately for a glass obtained by baking the above paste at 600 to 650°C for 10 minutes. It is the average linear expansion coefficient between 50 and 350℃. In addition, as a comparative example, a conventional one is also listed in Material No. 7. In the same table, for the solder wettability of the upper conductor, Pb− containing 2% Ag
Sn eutectic solder was melted at 220°C ± 10°C, immersed in it for 5 seconds, then pulled out, and the area of the part of the upper conductor wetted by the solder was expressed in %. On the other hand, regarding the change in resistance value of the low antibody, the resistance value before forming the glass layer is R ₀ , the resistance value after forming the glass layer is R ₁ , and the rate of change in resistance value is R ₁ -
The value was R ₀ /R ₀ ×100. The insulation resistance of the glass layer is the resistance value at room temperature when DC 100V is applied between the second conductor (upper conductor) and the first conductor. Regarding dielectric installation and dielectric constant
This is the value at 1KHz. As is clear from Table 1, the glass according to the present invention can form a glass insulating layer at an extremely low temperature of 600 to 650°C, and the glass layer has excellent insulation properties and an expansion coefficient of 40.
It is approximately ×10 ^-7 /°C, which is slightly smaller than that of a normal SiC substrate. In addition, the upper conductor has excellent solder wettability.
It has excellent properties such as low antibody resistance change rate.

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Claims (1)

[Claims] 1. Consists of a glass powder of 60 to 68 and a low thermal expansion filler having a coefficient of thermal expansion smaller than that of the glass, expressed as 1% by weight, and the glass powder is expressed as 60 to 68% by weight.
ZnO 40-65 B ₂ O ₃ 14-27 SiO ₂ 4-20 Al ₂ O ₃ 2-8 SnO ₂ 0.05-2.0 Contains at least one selected from MgO, CaO, BaO and SrO and a combination thereof. A composition for a thick film circuit insulating layer, characterized in that it contains at least one selected from _Li2O.Na2O and _K2O in an amount of _0.05 to 10 and a total amount of 0.05 to 3. 2. The composition for a thick film circuit insulating layer according to claim 1, wherein the low thermal expansion filler is quartz glass, high silicate glass, cordierite, β-eucryptite or β-spodiume.