JPH0219988B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a silicon carbide substrate for electronic circuits and a method for manufacturing the same, and in particular, the present invention relates to a silicon carbide substrate having through holes and provided with extremely stable electrical insulation within the through holes and on the surface of the substrate. The present invention relates to a silicon carbide substrate for integrated circuits or IC packages, and a method for manufacturing the same. Recently, with the development of electronic industry technology, electronic component materials such as semiconductors are becoming smaller or more highly integrated. Therefore, as electronic components become more highly integrated, the amount of heat generated within integrated circuits increases, and the heat dissipation of the substrate has become an important issue. By the way, various substrates for the electronic industry have been known and put into practical use, and alumina sintered bodies, glass, etc. have been used for applications that require particularly high reliability. However, the conventionally used substrates as mentioned above have low thermal conductivity and poor heat dissipation, making it difficult to solve the problem of heat accumulation, which is an extremely large obstacle in promoting higher integration of electronic components. ing. Materials such as beryllia or enamel have been considered as materials to solve the above problem. However, the former beryllia has the disadvantage that it is difficult to manufacture and handle due to the toxicity of beryllia, while the latter enamel has a high coefficient of thermal expansion because it is based on a metal plate, and the frit has a dogbone structure. Not only is it difficult to cut after printing, but the enamel also has cracks, making it impossible to perform laser trimming. As mentioned above, all conventionally known substrates have various drawbacks. Therefore, the present inventors have conducted various studies in order to provide a substrate that can solve the above-mentioned drawbacks, that is, a substrate that has high thermal conductivity and has extremely excellent characteristics as a substrate for highly integrated circuits or a substrate for IC packages. As a result, silicon carbide sintered bodies have higher thermal conductivity and higher thermal shock resistance than alumina sintered bodies (hereinafter referred to simply as alumina substrates), which have been widely used as substrates. It has high strength at both room temperature and hot temperature, and since the coefficient of thermal expansion of alumina substrate is significantly different from that of silicon chips normally used for integrated circuits, silicon chips can be directly placed on alumina substrates. However, the coefficient of thermal expansion of silicon carbide sintered bodies is almost the same as that of the silicon chips, and silicon carbide sintered bodies have the advantage of allowing silicon chips to be directly bonded to the substrate surface. I came up with the idea that I have However, silicon carbide sintered bodies have not been used as substrates until now because they do not have electrical insulation properties. Based on the above-mentioned viewpoints, the present inventors conducted various studies on methods of imparting electrical insulation properties to silicon carbide sintered bodies in order to apply them as substrates, and previously filed Japanese Patent Application No. 56-209991. Patent Application No. 56-209992 entitled "Silicon Carbide Substrate and Method for Producing the Same", and March 29, 1981 entitled "Silicon Carbide Substrate and Method for Producing the Same" A patent application was filed for the invention. Incidentally, integrated circuit boards and IC package boards are generally provided with through holes for the purpose of multilayering. However, the diameter of the through-hole is usually extremely small, and in silicon carbide substrates having through-holes, not only is oxygen likely to be insufficiently diffused into the through-hole during oxidation treatment, but also the through-hole It is difficult to uniformly apply the aluminum-containing material or coating agent composition to the inside of the through hole, resulting in uneven thickness of the insulating coating within the through hole, resulting in irregular pore diameters or, in severe cases, blockage. Therefore, it has the disadvantage that it is extremely difficult to form a uniform and highly reliable insulating film on the inside of the through hole, and silicon carbide substrates have a disadvantage in that they are difficult to form when compared to commonly used alumina substrates. However, since the dielectric constant is extremely high and the signal propagation speed is slow, it has the drawback that it is extremely difficult to put it into practical use. Therefore, the present inventors conducted research to improve the insulation resistance and reliability in the through holes of the silicon carbide substrate, and as a result of repeated research on the dielectric constant, etc. By fitting the ends of the insulator into close contact with the insulating coating layer formed on the substrate without any gaps, extremely stable electrical insulation can be imparted to the inside of the through-hole and the surface of the substrate. I can,
Furthermore, the present invention has been completed based on the new discovery that it has the surprising effect of significantly reducing the capacitance between through holes. The present invention provides a silicon carbide substrate for electronic circuits that provides extremely stable electrical insulation within the through holes and on the substrate surface, and significantly reduces the capacitance between the through holes. The purpose is to provide the following. According to the present invention, a silicon carbide substrate has a cylindrical insulator fitted in a through hole, and an end of the insulator is in close contact with an insulating coating layer on the substrate. The above object can be achieved by the method of manufacturing the same. Next, the present invention will be explained in detail. According to the present invention, it is necessary to have a cylindrical insulator fitted in a through hole, and the end of the insulator is in close contact with the insulating coating layer on the substrate.
The reason why it is necessary to have a cylindrical insulator fitted inside the through hole is that, as mentioned earlier, it is extremely difficult to form an insulating coating layer inside the through hole. This is because by fitting an insulator formed into a shape into the through hole, the inside of the through hole can be easily insulated, and the capacitance between the through holes can be significantly reduced. This is because it also has the advantage of being able to form through holes with uniform diameters. The reason why it is necessary that the ends of the insulator are in close contact with the insulating coating layer on the board is that conductors are usually wired in the through holes by the plating method, or conductors such as leads are wired in the through holes. is inserted and its end is connected to the wiring on the board by soldering, for example, but if the end of the cylindrical insulator is not in close contact with the insulating coating layer on the board without any gaps, This is because the conductor enters the gap between the cylindrical insulator and the insulating coating layer on the substrate, causing insulation failure. According to the present invention, it is preferable that the cylindrical insulator is at least one selected from the groups (a), (b), (c), and (d) described in the claims. The reason for this is that groups (a), (b), (c), and (d) all have high insulation resistance, low dielectric properties, and electrical properties that can reduce the capacitance between through holes. In particular, the porcelain of group (a) has excellent mechanical properties, thermal properties, and chemical resistance stability, while the glass of group (b) has excellent formability and adhesion to the insulating coating layer on the substrate. Group (C) has excellent mechanical properties, thermal properties, chemical stability, and thermal shock resistance.
Group (d) resins have relatively excellent heat resistance. In addition,
As the porcelain of group (A), it is advantageous to use, for example, alumina porcelain, forsterite porcelain, steatite porcelain, zircon porcelain, cordierite porcelain, mullite porcelain, and spinel porcelain. According to the invention, the cylindrical insulator is 0.01 to 2 mm
It is advantageous to have a wall thickness within the range of . The reason for this is that if the wall thickness is thinner than 0.01 mm, the mechanical strength will be weak and it will not only be difficult to fit into the through hole, but also the reliability of electrical insulation will decrease, while if it is thicker than 2 mm, the through hole This is because the hole diameter must be increased and the number of through holes per unit area decreases. According to the present invention, the insulating coating layer on the silicon carbide substrate includes a coating layer (e) as described in the claims and a welding layer as described in the claims welded on the coating layer (e). It is preferable that it consists of a layer (f). The reason for this is that the coating layer (E) is mainly composed of silicon dioxide, which is formed by oxidizing the surface of the silicon carbide substrate, and the welding layer (E) is formed by oxidizing the surface of the silicon carbide substrate.
It is possible to form a welding layer (F) with extremely good wettability with the oxide constituting the silicon carbide substrate and with few defects such as pinholes, and the coating layer (E) has an intricate transition layer with the silicon carbide substrate. Furthermore, this coating layer (E) and the welding layer (F) form a eutectic layer and are integrated, forming an insulating coating layer with extremely good adhesion to the silicon carbide substrate. This is because it can be done. According to the present invention, the film thickness of the coating layer (e) is 0.01~
Advantageously, it is in the range of 25 μm. The reason for this is that if the film thickness is less than 0.01 μm, not only will it not be possible to significantly improve the bonding properties with the welding layer (F) welded onto the coating layer (E), but also the formation of a complicated transition layer will occur. Due to the insufficient
This is because a coating layer (e) thicker than m takes an extremely long time to form and is not efficient.
Optimal results are obtained within the range of 0.1 to 10 μm. According to the present invention, it is advantageous for the coating layer (e) to contain aluminum oxide when a relatively thick film and stable insulation are required.
The reason for this is that aluminum oxide prevents cristobalite formation when the coating layer (e) is formed, and can form an extremely dense coating layer (e). Further, according to the present invention, when a coating layer (E) having a thickness of more than 0.1 μm is required, the coating layer (E)
of aluminum oxide and silicon dioxide contained in
Advantageously, the _{Al2O3 / SiO2} molar ratio is in the range from 0.024 to 1.8. The reason is the above-mentioned Al ₂ O ₃ /SiO ₂
If the molar ratio is less than 0.024, silicon dioxide produced by oxidation of silicon carbide will form cristobalite crystals, making it difficult to form a uniform and dense coating layer (e), while if it is greater than 1.8, the coating layer will be difficult to form.
(E) has a high melting point, and it is not only necessary to heat it to an extremely high temperature to form the coating layer (E), but also because the oxidation of the silicon carbide substrate becomes uneven, it is difficult to form a dense coating with a uniform thickness. This is because it is difficult to form a layer (e), and the most preferable results are obtained within the range of 0.05 to 1.0. According to the present invention, the welding layer (f) includes aluminum, silicon, phosphorus, boron, germanium, arsenic,
antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium,
The main component is at least two oxides selected from calcium, magnesium, barium, and strontium. According to the present invention, the thickness of the welding layer (F) is 1 to 1.
It is preferably within the range of 80 μm. The reason for this is that if the thickness of the welding layer (F) is thinner than 1 μm, the insulation of the silicon carbide substrate cannot be stably obtained, whereas if it is thicker than 80 μm, the insulation including the coating layer (E) cannot be obtained. The silicon carbide film becomes significantly thicker, and the effect of the difference in coefficient of thermal expansion between the insulating film and silicon carbide becomes significant, which not only makes the insulating film more likely to peel off, but also
This is because the thermal conductivity deteriorates significantly, making it difficult to obtain a substrate with high thermal conductivity, which is the object of the present invention.
Optimally, the range is m. According to the invention, the thickness of the substrate is 0.1~30mm
It is preferable that it is within the range of . The reason is that the thickness of the board is preferably as thin as possible in order to promote miniaturization of electronic components and improve heat dissipation, but if the thickness is thinner than 0.1 mm, the strength of the board itself will weaken and it will not be used as a board. It is difficult to
Further, if the thickness is more than 30 mm, it is not only difficult to miniaturize electronic components, but also the cost required for the board increases, which is uneconomical. Next, the electrical characteristics of the silicon carbide substrate having through holes of the present invention will be explained. The electrical resistance value of silicon carbide sintered bodies measured based on the Japanese Industrial Standards (JIS-C-5012-7.3) is usually low, approximately 10 ⁵ Ω or less when the applied voltage is 25 V, making it difficult to apply as a substrate. The insulation resistance value of the insulating film layer portion of the silicon carbide substrate of the present invention is 3×10 ⁹ Ω or more when the applied voltage is 25 V, and
In the case of 100V, it is 1×10 ⁹ to 8×10 ¹³ Ω, and the withstand voltage measured based on Japanese Industrial Standards (JIS-C-2110-8.3) is about 0.35 KV or more. Next, a method for manufacturing a silicon carbide substrate of the present invention will be explained. According to the method of the first aspect of the present invention, the surface of the silicon carbide substrate is oxidized to form the coating layer (e),
Next, the welding layer (F) is fitted onto the coating layer (E) and into the through-hole of the silicon carbide substrate at least one selected from the groups (A), (B) and (C). According to the method of welding the seeds to the cylindrical insulator or the method of the second invention, the surface of the silicon carbide substrate is oxidized to form the coating layer (E), and then the welding layer (F) is deposited on the surface of the silicon carbide substrate. The coating layer (E) is welded onto the coating layer (E), and at least one cylindrical insulator selected from the group (D) is fitted into the through hole of the silicon carbide substrate. The silicon carbide substrate of the present invention is manufactured by at least one of the following methods: and a method of bringing the material into close contact with an insulating coating layer consisting of a welding layer (f). According to the present invention, it is necessary to oxidize the surface of the silicon carbide substrate to form the coating layer (e). The reason for this is that by oxidizing the surface of the silicon carbide substrate to form the coating layer (e), the wettability with the oxide constituting the welding layer (f) is significantly improved, and pinholes etc. This is because an extremely uniform insulating coating layer with no defects can be obtained, and the coating layer (e) has a silicon carbide substrate and an intricate transition layer, and the coating layer (e) and the welding layer This is because since the oxide constituting (f) is integrated with the oxide, it is possible to form an insulating coating layer that has extremely good adhesion to the silicon carbide substrate. The mechanism by which the adhesion between the silicon carbide substrate and the insulating coating layer is significantly improved by oxidizing the silicon carbide substrate to form the coating layer (E) is that the oxidation treatment Impurities adhering to the surface of the silicon carbide substrate, such as free carbon, are removed so that there is no foreign material layer between the silicon carbide substrate and the insulating coating layer, and the oxidation treatment causes the surface of the silicon carbide substrate to become microscopic. This results in a roughened state, which can significantly increase the bonding area with the insulating coating layer, and the insulating coating layer and the silicon carbide sintered body are bonded by an intricate transition layer. It is presumed that this is the case. In the present invention, when forming a coating layer (e) containing aluminum oxide, the aluminum-containing material is applied to the surface of the silicon carbide substrate, and then heated in an oxidizing atmosphere to coat the surface of the silicon carbide substrate. It is advantageous to carry out an oxidation treatment. The aluminum-containing material is one that can supply aluminum in the form of an oxide in the oxidizing atmosphere when the coating layer (e) is formed, such as alumina sol, metal aluminum, aluminum-containing alloy, aluminum oxide, water, etc. Aluminum oxide,
It is preferable to use at least one selected from aluminate, aluminosilicate, aluminum phosphate, and aluminum acetate. In particular, alumina sol is extremely fine and reactive when the coating layer (e) is formed. This is the most suitable because it can supply a high amount of aluminum oxide. The amount of the aluminum-containing material to be applied depends on the desired thickness of the coating layer (e) and the Al 2 O 3 /Al ₂ O ₃ ratio of aluminum oxide and silicon dioxide.
It is determined by the SiO ₂ molar ratio, and the film thickness is thicker than 0.1 μm and the Al ₂ O ₃ /SiO ₂ molar ratio is 0.024 to 1.8 (e).
In ^order _to obtain _a
The most preferred range is 1.2 mg/cm ² . According to the present invention, the silicon carbide substrate is preferably heated to a temperature within the range of 750 to 1650°C in an oxidizing atmosphere for oxidation treatment, and the silicon carbide substrate is preferably heated to a temperature within the range for at least 10 minutes. It's advantageous. The reason for this is that if the heating temperature is lower than 750°C, the oxidation rate is slow and it is difficult to efficiently generate the coating layer (H), whereas if it is higher than 1650℃, the oxidation rate is extremely fast and the coating layer (H) is difficult to form efficiently. It is not only difficult to control the film thickness to the desired thickness, but also the film layer (H)
This is because air bubbles are generated between the silicon carbide substrate and the silicon carbide substrate, which deteriorates the adhesion. The reason why it is advantageous to heat to a temperature within the above range for at least 10 minutes is because if the heating time is shorter than 10 minutes, it is difficult to obtain a coating layer (e) with the desired thickness. . Note that the best results can be obtained when the heating temperature is within the range of 900 to 1450°C. According to the invention, it is advantageous to include water vapor in the oxidizing atmosphere. The reason is that by containing water vapor in the atmosphere, oxidation of the silicon carbide substrate surface can be promoted;
This is because the coating layer (e) can be efficiently formed even at a relatively low temperature. According to the present invention, when it is required to form a film layer (e) having a relatively thick film thickness in a short time, a silicon-containing material may be applied to the surface of the silicon carbide substrate. is advantageous. The prefilling silicon-containing material is one that can supply silicon in the form of an oxide in the oxidizing atmosphere when the coating layer (e) is formed, and includes, for example, silica sol, metallic silicon, silicon-containing alloy, silicon dioxide, and At least one selected from silicon oxide and various silicates can be used. According to the present invention, it is advantageous that at least 30% by weight of the silicon dioxide contained in the coating layer (e) is silicon dioxide produced by oxidation of silicon carbide. The reason for this is that if the amount of silicon dioxide produced by the oxidation of silicon carbide is less than 30% by weight, the formation of an intricate transition layer with the silicon carbide substrate will be insufficient, resulting in poor adhesion. be. According to the present invention, a melting point depressant can be applied to lower the melting point of the coating layer (e) to promote eutectic formation and improve adhesion to the silicon carbide substrate. As the melting point depressant, at least one of an alkali metal-containing substance and an alkaline earth metal-containing substance can be used. The alkali metal-containing substance and the alkaline earth metal-containing substance are capable of supplying an alkali metal or an alkaline earth metal in the form of an oxide in the oxidizing atmosphere when the coating layer (e) is formed, for example. At least one element selected from lithium, sodium, potassium, beryllium, magnesium, and calcium or a compound thereof can be used. In addition, since the oxide generated from the melting point depressant deteriorates the electrical insulation properties of the coating layer (E), the content in the coating layer (E) should be 60% or less in terms of oxide molar amount. In particular, when high insulation is required, it is preferably 30% or less. According to the present invention, the coating layer (e) may also contain an oxide of phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, or the like. According to the method of the first aspect of the present invention, the coating layer (e) formed by the method described above contains at least two of the elements selected from the group (g) or compounds thereof. After applying the coating agent composition, the welding layer is heated.
(F) is a cylindrical insulator of at least one selected from the groups (A), (B), and (C) inserted into the coating layer (E) and the through holes of the silicon carbide substrate; By welding it to the body, the cylindrical insulator fitted in the through hole and the insulating coating layer on the substrate can be brought into close contact with each other without any gaps, resulting in an extremely reliable insulating coating layer and A silicon carbide substrate having through holes with excellent insulation properties can be obtained. Further, according to the method of the second invention of the present invention, the welding layer (f) is formed by applying the coating agent composition and heating it in the same way as the method of the first invention.
is welded to the coating layer (E), and at least one cylindrical insulator selected from the group (V) is fitted into the through hole of the silicon carbide substrate, and the coating layer (Ho) is welded to the coating layer (E). ) and the welding layer (F), the insulating film layer on the substrate can be brought into close contact with the insulating film layer without any gaps;
A silicon carbide substrate having an extremely reliable insulating coating layer and through holes with excellent insulation properties can be obtained. In the method of the second invention, the method of bringing the cylindrical insulator into close contact with the insulating coating layer includes fitting a resin previously formed into a cylindrical shape into a through hole, and then locally heating the end portion. Advantageous is the method of fusion bonding to the insulating coating layer. The coating agent composition used in the present invention is selected from aluminum, silicon, phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium, calcium, magnesium, barium, and strontium. It contains at least two of the elements or compounds thereof, and becomes a eutectic oxide when it is deposited on the coating layer (e). According to the present invention, various methods such as a screen printing method, a dipping method, a spraying method, and a brushing method can be applied to apply the coating agent composition. According to the present invention, the welding layer (F) is welded by applying the coating agent composition in the manner described above and, if necessary, sufficiently drying and then heating. It is advantageous for the atmosphere during the welding to be a non-oxidizing atmosphere in order to prevent bubbles from being generated in the welding layer (f) due to the CO gas generated when the silicon carbide substrate is oxidized during welding. . Further, according to the present invention, the heating temperature during the welding is preferably within the range of 300 to 1200°C.
The reason for this is that if the temperature is lower than 300°C, it is difficult to weld the coating layer (e) and the welding layer (f) to each other, while if it is higher than 1200°C, the coating agent composition will form. The viscosity of the eutectic oxide decreases significantly, which not only makes it difficult to form a welding layer (F) with a uniform thickness, but also causes the eutectic oxide to enter the through hole, causing damage to the through hole. This is because the pore diameter may be reduced or, if the pore size is significant, the pore may be blocked. Next, the present invention will be explained with reference to examples. Example 1 A silicon carbide substrate is a thin plate having 40 through holes with an inner diameter of approximately 1 mm at intervals of 2.54 mm as shown in FIG. 1, and the surface thereof is polished in advance except for inside the through holes. Finally, I used one that had been surface-finished with a #200 whetstone. The silicon carbide substrate is a pressureless sintered body of silicon carbide containing 1.0% by weight of boron and 2.0% by weight of free carbon, and has a density of 3.1 g/cm ³ .
The size is ×2 mm. The silicon carbide substrate was placed in a tube furnace having an inner diameter of 40 mm, and oxygen gas was charged into the tube furnace at a rate of 1/min, and the substrate was maintained at 1400° C. for 3 hours for oxidation treatment. By the above treatment, a SiO ₂ coating layer (corresponding to the coating layer (e)) having a thickness of about 0.05 μm was obtained on the surface of the silicon carbide substrate. Next, a cylinder made of alumina sintered body having a shape as shown in FIG. 2 and having an outer diameter of about 1 mm and a wall thickness of 0.25 mm at the part to be fitted into the through hole was inserted into the through hole of the substrate as shown in FIG. 3. After fitting as shown, a coating agent composition containing SiO ₂ , B ₂ O ₃ and ZnO as main components was applied onto the oxide film of the substrate by screen printing, and dried at 110° C. for 1.5 hours. This process was repeated twice. The silicon carbide substrate coated with the coating agent composition was placed in a firing furnace and heated at a rate of 10°C/min.
It was held at the maximum temperature of 650°C for 60 minutes and then cooled. The calcination was performed in air up to 300°C, and thereafter in an argon gas atmosphere. The obtained insulating film had a thickness of about 0.05 μm,
Almost no defects such as pinholes or microcracks were observed, and the surface was extremely smooth.
Furthermore, the adhesion between the insulating film and the alumina sintered body was extremely good. The thickness of the portion of the insulating film corresponding to the welding layer (F) is approximately 30 μm. The insulation resistance of the silicon carbide substrate having the insulating film is 5×10 ¹² Ω when the applied voltage is 25 V,
The withstand voltage was 0.8KV. The above insulation resistance is JIS-
C-5012-7.3, withstand voltage JIS-C-2110-8.3
Measured based on. In addition, the insulation resistance between the through holes was measured by inserting a Kovar wire with a wire diameter of 0.45 mm into the through hole, and it was found to be 1 × 10 ¹² Ω between adjacent through holes, and the capacitance (frequency :1MHz) was 0.7pF. Example 2 1.6g of calcium chloride and 1% by weight of alumina sol
Example 1 in an aqueous solution dissolved in 100 ml of an aqueous solution.
After the silicon carbide substrate was immersed in the same manner as that used in 1, it was placed in a dryer and dried at 110°C for 1 hour.
Approximately 0.13 mg/cm ² of alumina sol in terms of Al ₂ O ₃ and calcium chloride of approximately 0.20 mg/cm ² in terms of CaO were present on the surface of the silicon carbide substrate. Next, the silicon carbide substrate was placed in a tube furnace having an inner diameter of 40 mm and subjected to oxidation treatment. The oxidation treatment was carried out at 1400° C. for 3 hours by charging oxygen gas into the tube furnace at a ratio of 1/mm. The obtained oxide film (corresponding to the welding layer (e)) was transparent and glassy, had a thickness of about 2.7 μm, and had a smooth surface. Note that the Al ₂ O ₃ /SiO ₂ molar ratio of this oxide film was 0.30. Furthermore, after fitting a cylinder made of alumina sintered body into the through hole of the substrate in the same manner as that used in Example 1, SiO ₂ was placed on the oxide film of the substrate.
A coating agent composition containing BaO and PbO as main components was applied by screen printing, and 100%
It was dried at ℃ for 2 hours. A silicon carbide substrate coated with the coating agent composition was sintered in the same manner as in Example 1, but at a sintering temperature of 900℃.
C. to obtain a silicon carbide substrate having electrical insulation properties inside the through holes and on the surface of the substrate. The properties of the obtained silicon carbide substrate were measured in the same manner as in Example 1 and are shown in Table 1.

【table】

[Table] Example 3 Same as Example 2, but electrical insulation was imparted to the inside of the through hole and the surface of the board by using the cylindrical insulator shown below to be fitted into the through hole. A silicon carbide substrate was obtained. All of the obtained silicon carbide substrates were able to fully satisfy the purpose of the present invention in terms of electrical properties. Forsterite porcelain, steatite porcelain, zircon porcelain, cordierite porcelain, mullite porcelain, spinel porcelain, borosilicate glass, soda glass, quartz glass, lead glass, silicon nitride, sialon. Example 4 The method is almost the same as in Example 2, but after forming an oxide film by changing the temperature and time during the oxidation treatment, electrical insulation was applied in the through holes and on the substrate surface in the same manner as in Example 2. A silicon carbide substrate with properties imparted to it was obtained. The properties of the obtained silicon carbide substrate were measured in the same manner as in Example 1 and are shown in Table 1. Example 5 A method similar to Example 2 was carried out, but after forming an oxide film using an alumina sol aqueous solution containing silicon-containing substances, melting point depressants, or other additives shown in Table 1. A silicon carbide substrate was obtained in the same manner as in Example 2, with electrical insulation provided within the through holes and on the substrate surface. Table 1 shows the values of each substance present on the surface of the silicon carbide substrate after drying, converted into oxide weights, and the characteristics of the silicon carbide substrate measured in the same manner as in Example 1. Example 6 SiO 2 and BaO were deposited on the oxide film of a silicon carbide substrate on which an oxide film was formed in the same manner as in Example ₂ .
A coating agent composition containing CaO as a main component was applied by screen printing and dried at 100°C for 2 hours. A silicon carbide substrate coated with the coating agent composition was fired in the same manner as in Example 1, but at a different firing temperature.
The temperature was raised to 1100°C to form an insulating film. Next, a tube made of polyimide resin having a shape similar to that used in Example 1 and having an outer diameter of about 1 mm and a wall thickness of 0.3 mm to be fitted into the through hole was inserted into the through hole of the substrate. Thereafter, the end portions were locally heated to bring them into close contact with the insulating film, thereby obtaining a silicon carbide substrate with electrical insulation provided within the through holes and on the substrate surface. The properties of the obtained silicon carbide substrate were measured in the same manner as in Example 1 and are shown in Table 1. Example 7 Same as Example 6, but a silicon carbide material was used as a cylindrical insulator to be fitted into the through hole as shown below to provide electrical insulation inside the through hole and on the substrate surface. I got the board. All of the obtained silicon carbide substrates were able to fully satisfy the purpose of the present invention in terms of electrical properties. Triazine resin, polyparabanic acid resin, polyamideimide resin. As described above, according to the present invention, a silicon carbide sintered body having high thermal conductivity and a coefficient of thermal expansion approximately the same as that of a silicon chip normally used as an integrated circuit can be made into a through-hole. It can be supplied as a substrate for integrated circuits or as a substrate for IC packages, and the effect of contributing to industry is extremely large.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a silicon carbide substrate having through holes used in Example 1, and FIG. 2 is a perspective view of a cylindrical insulator fitted into the through holes used in Example 1. , FIG. 3 is a sectional view showing a state in which a cylindrical insulator is fitted into a through hole.

Claims (1)

[Claims] 1. An electronic circuit comprising a cylindrical insulator fitted in a through hole, the end of the insulator being in close contact with an insulating coating layer on a substrate. Silicon carbide substrate. 2. The substrate according to claim 1, wherein the cylindrical insulator is at least one selected from the following groups (a), (b), (c), and (d). (a) Porcelain whose main component is at least one oxide selected from aluminum, magnesium, silicon, and zirconium. (b) At least two oxides selected from aluminum, silicon, phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium, calcium, magnesium, barium, and strontium. Glass whose main component is material. (c) silicon nitride, sialon, aluminum nitride,
boron nitride. (d) Polyimide resin, triazine resin, polyparabanic acid resin, polyamideimide resin. 3 The insulating coating layer on the substrate is the following coating layer (e)
and the following welding layer (f) welded onto the coating layer (e). (e) A coating layer whose main component is silicon dioxide. (f) At least two oxides selected from aluminum, silicon, phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium, calcium, magnesium, barium, and strontium. A welding layer whose main component is a substance. 4. The substrate according to claim 3, wherein silicon dioxide, which is the main component of the coating layer (e), is mainly produced by oxidizing silicon carbide that constitutes the substrate. 5 The surface of the silicon carbide substrate is oxidized to form the following coating layer (e), and then the following welding layer (f) is applied on the coating layer (e) and in the through holes of the silicon carbide substrate. A method for producing a silicon carbide substrate for electronic circuits, which comprises welding a fitted cylindrical insulator of at least one selected from the following groups (a), (b), and (c). (a) Porcelain whose main component is at least one oxide selected from aluminum, magnesium, silicon, and zirconium. (b) At least two oxides selected from aluminum, silicon, phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium, calcium, magnesium, barium, and strontium. Glass whose main component is material. (c) silicon nitride, sialon, aluminum nitride,
boron nitride. (e) A coating layer whose main component is silicon dioxide. (f) At least two oxides selected from aluminum, silicon, phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium, calcium, magnesium, barium, and strontium. A welding layer whose main component is a substance. 6. The manufacturing method according to claim 5, wherein the silicon carbide substrate is oxidized within a temperature range of 750 to 1650°C to form the coating layer (e). 7. The welding layer (f) contains at least two of the elements selected from the group (g) below or their compounds.
7. The production method according to claim 5 or 6, which is produced by applying a coating composition containing seeds and then heating. (g) Aluminum, silicon, phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium, calcium, magnesium, barium, strontium. 8 After applying the coating agent composition,
The manufacturing method according to any one of claims 5 to 7, wherein heating is performed within a temperature range of 300 to 1200°C. 9. Oxidizing the surface of the silicon carbide substrate to form the following coating layer (E), then welding the following welding layer (F) onto the coating layer (E), and then forming a through-hole of the silicon carbide substrate. At least one type of cylindrical insulator selected from the following group (d) is fitted into the hole and welded to the insulating coating layer consisting of the coating layer (e) and the welding layer (f). A method for manufacturing a silicon carbide substrate for electronic circuits. (d) Polyimide resin, triazine resin, polyparabanic acid resin, polyamideimide resin. (e) A coating layer whose main component is silicon dioxide. (f) At least two oxides selected from aluminum, silicon, phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium, calcium, magnesium, barium, and strontium. A welding layer whose main component is a substance. 10. The manufacturing method according to claim 9, wherein the silicon carbide substrate is oxidized within a temperature range of 750 to 1650°C to form the coating layer (e). 11 The welding layer (f) is formed by applying and heating a coating composition containing at least two of the elements selected from the group (g) below or their compounds. A manufacturing method according to claim 9 or 10. (g) Aluminum, silicon, phosphorus, boron, germanium, arsenic, antimony, bismuth, vanadium, zinc, cadmium, lead, sodium, potassium, lithium, calcium, magnesium, barium, strontium. 12 After applying the coating agent composition,
The manufacturing method according to any one of claims 9 to 11, wherein heating is performed within a temperature range of 300 to 1200°C.