JPH0475868B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing insulating porcelain that can provide a single-layer or multi-layer circuit board. [Prior Art] A conventional insulating ceramic substrate is formed using alumina as a main component (90% by weight or more of alumina). However, in order to obtain an alumina porcelain substrate, the raw material mixture must be fired at a high temperature of 1500 to 1600°C, so the electrode material that can be used when simultaneously firing the raw material mixture green sheet and electrode material is molybdenum. , limited to high melting point metals such as tungsten, Au, Ag, Pd, Cu,
Metals such as Ni, which have excellent electrical properties but have low melting points, could not be used. Furthermore, since the firing temperature for obtaining the alumina ceramic substrate is high, the cost of the firing furnace has inevitably increased. In order to solve the above problems, alumina
Glass-based low-temperature fired porcelain was developed. This alumina-glass based low temperature fired porcelain is obtained by firing a mixture of alumina powder and glass powder in a weight ratio of approximately 1:1. This low-temperature fired porcelain is obtained by firing at temperatures below 1000℃, so
It becomes possible to co-fire with electrode materials such as low melting point Au, Ag, Pd, Cu, and Ni. [Problems to be solved by the invention] However, when manufacturing conventional low-temperature fired porcelain,
Since borosilicate glass, barium borosilicate glass, calcium borosilicate glass, lead borosilicate glass, etc. are used as the glass powder added to the alumina raw material, the raw material cost of the glass powder increases, and the cost of the finished porcelain increases. It inevitably got higher. To explain this in more detail, all of the above glasses are made by melting the raw materials at high temperatures, rapidly cooling them, and mechanically crushing the resulting glass lumps. Glass powder made in this way has poor productivity and is expensive. Further, the particle size of the glass powder needs to be at least 10 μm or less, preferably 5 μm or less. If glass is insufficiently pulverized and has a coarse particle size, it will have a significant negative effect on the properties of the ceramic after firing, especially its strength. For this reason, special care must be taken when shattering glass.
Poor productivity. Currently, the price of glass powder used for low-temperature firing porcelain with alumina glass diameter is 10,000 yen.
It is about yen/kg. Alumina powder is approximately 300 yen/Kg
Since it is much cheaper than glass powder, alumina-glass low-temperature firing ceramic, which is a 1:1 mixture of both in a weight ratio, costs about 5,000 yen/kg based on raw materials.
It turns out that. This price is quite high for a ceramic substrate for electronic components, and for this reason, low-temperature fired ceramic substrates have not become widespread. Therefore, an object of the present invention is to provide a manufacturing method that can significantly reduce the cost of low-temperature fired porcelain. [Means for Solving the Problems] The first invention of the present application for solving the above problems and achieving the above objects consists of 50 to 60 parts by weight of mullite and 25 to 35 parts by weight of danbrite. and 5-20
A method for producing insulating porcelain, which comprises preparing a mixture consisting of parts by weight of petalite and 2 to 8 parts by weight of forsterite, forming a molded body of this mixture, and firing this molded body. It is something. The second invention of the present application is characterized in that 1 to 5 parts by weight of chromium trioxide is further added to the mixture of the first invention to form a molded body, and this is fired. [Function] Since the mullite in the above invention contains 3Al ₂ O ₃ .2SiO ₂ as a main component, it can provide an alumina component for porcelain. However, since this mullite mainly provides the alumina component in porcelain, if the amount of mullite in the porcelain raw material mixture is less than 50 parts by weight, it will not be possible to obtain porcelain with high strength; If the amount exceeds 1000℃
It becomes impossible or difficult to perform firing under the following conditions. Danburite is the main ingredient
Since it contains CaSi ₂ B ₂ O ₈ , it functions as a glass component to enable low-temperature firing. Therefore, if the amount of Danbrite is less than 25 parts by weight,
It becomes difficult or impossible to fire at temperatures below 1000°C, and on the other hand, if it exceeds 35 parts by weight, the strength of the porcelain decreases. Petalite is also called petalite, and its main component is Li ₂ O.
It contains Al ₂ O ₃ 8SiO ₂ . Therefore, it mainly provides a glass component to enable low-temperature firing, and if this amount is less than 5 parts by weight,
It becomes difficult to fire at temperatures below 1000°C, and if it exceeds 20 parts by weight, the insulation resistance of the porcelain will decrease. Forsterite contains 2MgO.SiO ₂ as a main component and contributes to increasing the strength of porcelain. If this forsterite is less than 2 parts by weight, the strength of the porcelain will decrease,
If it exceeds 8 parts by weight, firing at temperatures below 1000°C becomes difficult or impossible. Chromium trioxide (Cr ₂ O ₃ ) in the second invention of the present application colors porcelain dark green.
If the amount of chromium trioxide is less than 1 part by weight, sufficient coloring is not possible, and if it exceeds 5 parts by weight, the strength of the porcelain decreases. Example 1 Next, Example 1 (including a comparative example) of the present invention will be described. In order to obtain the raw material composition shown in Sample No. 1 in Table 1, 550 g (55 parts by weight) of mullite powder, 300 g (30 parts by weight) of danburite powder, and 100 g of petalite powder were used.
(10 parts by weight) and 50 g (5 parts by weight) of forsterite powder were weighed and put into a ball mill. Next, 300 g of acetone as a solvent, 200 g of trichloroethylene, and 15 g of oleic acid as a dispersant were added to a ball mill and mixed for 24 hours. Next, 80 g of polyvinyl butyral resin powder as a binder and 80 g of dibutyl phthalate as a plasticizer were further added to the ball mill and mixed for 12 hours to form a slurry. Next, this slurry was slip casted using a doctor blade method and dried to a thickness of 0.8 mm.
Obtain a green sheet (unsintered porcelain sheet) of mm,
This was cut into 10cm squares. Next, three types of test pieces were made from this green sheet. The first test piece was obtained by punching out the green sheet into a disk shape with a diameter of 20 mm, and was used to examine insulation resistance. The second test piece was made by stacking three of the above green sheets at a temperature of 90℃ and a pressure of 250℃.
It was heat-pressed under the conditions of Kg/cm ² and cut into pieces with a length of 40 mm and a width of 5 mm, and the thickness was approximately 2.2 mm.
mm. This second test piece is for testing resistance temperature. The third test piece was made by printing a conductive paste containing Ag-Pd as a main component on one main surface of the green sheet to form a wiring pattern, stacking two sheets, and adding conductive paste on top. Stack one green sheet that is not printed on it for a total of 3 sheets,
After crimping this, it was cut into pieces of 3 mm in length and 15 mm in width, and the thickness was approximately 2.2 mm. This third
The test piece is for examining the state of electrode formation when low melting point electrode materials are co-fired. Next, each test piece was heated in air from room temperature to the firing temperature of 940°C at a rate of 300°C per hour.
After maintaining the temperature for 2 hours, the mixture was cooled to room temperature and fired. Subsequently, each test piece after firing was tested in the following manner. For the first specimen, commercially available
By printing Ag paste and baking it at 800℃ in air, we formed an electrode with a diameter of 15mm and applied a voltage of DC100V.
The insulation resistance was measured, and the resistivity of the porcelain was calculated from the diameter of the electrode and the thickness of the test piece. As a result, the average resistance of 10 test pieces was 2.0×10 ¹⁴ Ω·cm. Regarding the second test piece, the test piece was supported on both sides with a span length of 20 mm, and a load was applied to the midpoint between the two supporting points using a bending strength measuring device. The bending strength (flexural strength) was determined by calculation. As a result, the average of 25 test pieces was
It was 2500Kg/ ^cm2 . Regarding the third test piece, the conductivity of the wiring conductor was examined after printing a conductive paste and firing the same. As a result, in sample No. 1 and all the samples falling within the scope of the present invention, conductivity sufficient to function as a wiring conductor was obtained. Regarding Samples Nos. 2 to 20 in Table 1, test pieces were made under the same conditions as Sample No. 1, except that the raw material composition and firing temperature were changed, and the characteristics were examined using the same method.

【table】

[Table] According to the raw material compositions of samples No. 1 to 12 in Table 1, which belong to the scope of the present invention, the firing temperature is 1000°C or less (880°C
desired properties (flexural strength of 2000Kg/cm ² )
As described above, it is possible to provide porcelain with an insulation resistance of 1.0×10 ¹³ Ω·cm or more. On the other hand, according to the raw material compositions shown in Sample Nos. 13 to 20, which are outside the range of the present invention, a sintered body cannot be obtained even at a firing temperature of 100°C, or even if a sintered body is obtained, it has a strong resistance. The bending strength is less than 2000 kg/cm ² or the insulation resistance is less than 1×10 ¹³ Ω·cm. The reasons for limiting the raw material composition in the present invention are as follows. When mullite is 50 parts by weight as shown in sample No. 2, the desired properties can be obtained by firing at 900°C, but when mullite is 48 parts by weight as shown in sample No. 13, the desired flexural strength cannot be obtained. becomes less than the value. Therefore, the lower end of the desired range for mullite is 50 parts by weight. When mullite is 65 parts by weight as shown in sample No. 4, the temperature is 1000℃.
The desired characteristics can be obtained by firing sample No.
As shown in No. 14, in the case of 67 parts by weight, a sintered body cannot be obtained even by firing at 1000°C. Therefore, the upper limit of the desired range for mullite is 65 parts by weight. When Danbrite is 25 parts by weight as shown in sample No. 5, the desired properties can be obtained by firing at 1000°C, but when it is 23 parts by weight as shown in sample No. 15, sintering does not occur even when fired at 1000°C. I can't get a body. Therefore, the lower end of the desirable range for Danbrite is 25 parts by weight. Desired characteristics can be obtained when Danbrite is 35 parts by weight as shown in Sample No. 6, but when 37 parts by weight is used as shown in Sample No. 16.
In the case of parts by weight, the bending strength becomes lower than the desired value. Therefore, the upper limit of Danbright's desirable range is
It is 35 parts by weight. When the petalite content is 5 parts by weight as shown in Sample No. 7, the desired properties are obtained, but when the content is 4 parts by weight as shown in Sample No. 17, the desired properties are not obtained. Therefore, the lower end of the desirable range for petalite is 5 parts by weight. When the amount of petalite is 20 parts by weight as shown in sample No. 9, the desired characteristics are obtained, but when it is 22 parts by weight as shown in sample No. 18, the insulation resistance becomes lower than the desired value. Therefore, the upper limit of the desired range for petalite is 20 parts by weight. When the amount of forsterite is 2 parts by weight as shown in sample No. 10, the desired characteristics can be obtained, but as shown in sample No. 19, the desired characteristics can be obtained.
As shown in Figure 2, when the amount is 1 part by weight, the insulation resistance becomes lower than the desired value. Therefore, the lower limit of the desirable range for forsterite is 2 parts by weight. When the amount of forsterite is 8 parts by weight as shown in sample No. 12, the desired properties can be obtained, but when it is 10 parts by weight as shown in sample No. 20, a sintered body cannot be obtained even when fired at 1000 ° C. . Therefore, the upper limit of the desirable range for forsterite is 8 parts by weight. Example 2 The porcelain obtained in Example 1 is white. Therefore, the efficiency when cutting a ceramic substrate with a laser beam is poor. Colored porcelain may be required to solve this type of problem. In Example 1, porcelain was produced by adding chromium trioxide for coloring as shown in the raw material composition column of Table 2. In addition,
Each test piece of Samples Nos. 21 to 26 in Table 2 was sample No. 2, except that chromium trioxide (Cr ₃ O ₃ ) powder was included in the raw material composition.
It was produced using the same method as No. 1, and the characteristics were measured using the same method.

[Table] As is clear from Samples No. 21 to 24 in Table 2, when chromium trioxide is added in the range of 1 to 5 parts by weight, the porcelain is colored green or dark green, and it cannot be fired at temperatures below 1000℃. Desired properties are obtained. On the other hand, when the proportion of chromium trioxide is 0.5 parts by weight as shown in sample No. 25, the sample is only colored light green, and the coloring is insufficient. Further, when the proportion of chromium trioxide is 6 parts by weight as shown in sample No. 26, the bending strength becomes lower than the desired value even though the coloring is sufficient. Therefore, the preferred range of the proportion of chromium trioxide is 1 to 5 parts by weight. Example 3 In Examples 1 and 2, the molded bodies of the raw material compositions were fired in air (in an oxidizing atmosphere), but in order to investigate whether they could be fired in a non-oxidizing atmosphere (neutral or reducing atmosphere). Next, test pieces identical to the first, second, and third test pieces of Sample No. 1 were prepared in the same manner as Sample No. 1. However, as the conductive paste for the third test piece, a conductive paste containing nickel as a main component was used instead of the Ag-Pd paste. Next, the first, second and third test pieces were heated in air from room temperature to 600°C at a rate of 300°C per hour,
After maintaining the temperature at 600℃ for 1 hour, remove the atmosphere from air.
The atmosphere was changed to a reducing atmosphere (non-oxidizing atmosphere) consisting of 90% by volume of N ₂ and 10% by volume of H ₂ , the temperature was raised from 600°C to 940°C at a rate of 300°C per hour, and after holding at 940°C for 2 hours, It was fired by cooling to room temperature. Next, for the first test piece after firing, commercially available Cub paste was printed on both sides, and it was soaked in N2.
Electrodes with a diameter of 15 mm were formed by baking at 800°C. After that, the resistivity of the porcelain was determined in the same way as for sample No. 1, and the average of the 10 test pieces was 2.1×
10 ¹⁴ Ω·cm, which was not much different from sample No. 1. In addition, the bending strength of the second test piece after firing was determined using the same method and conditions as sample No. 1, and the average of 25 test pieces was 2500 Kg/cm ² , which was the same as sample No. 1. The values were the same. Further, regarding the third test piece, it was confirmed that a nickel layer functioning as a wiring conductor was obtained. Each test piece with the same raw material composition as sample No. 22 was fired in a reducing atmosphere in the same manner as above, and its properties were measured. The insulation resistance was 2.0 x 10 ¹⁴ Ωcm, and the bending strength was 2500 kg/cm. cm ² was not significantly different from that in the case of firing in air. Also, regarding coloration, no difference was observed between the test pieces fired in air and the test pieces under the above conditions. [Modifications] The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible. (1) The firing temperature of the oxidizing atmosphere in Example 1 can be varied within the range of preferably 800°C to 1000°C. Furthermore, depending on the electrode material, firing may be performed at a higher temperature such as 1000° C. or higher. (2) The firing temperature of the non-oxidizing atmosphere in Example 3 can be varied, preferably within the range of 800°C to 1000°C. Furthermore, baking may be performed at a temperature higher than 1000° C. if necessary depending on the electrode material. (3) In the firing step of Example 3, after firing in a reducing atmosphere, oxidative heat treatment may be performed in an oxidizing atmosphere at a temperature of about 500°C to 700°C. (4) The heat treatment in the oxidizing atmosphere in the firing step of Example 3 may be performed at another temperature in the range of approximately 500°C to 700°C. Note that the heating temperatures of the oxidizing atmosphere and the reducing atmosphere must be determined in consideration of the relationship with the electrode material. (5) Various additives may be included in the raw material composition as long as they do not impede the purpose of the present invention. (6) It is also applicable when using a mold to obtain a molded body of the raw material mixture without creating a green sheet. [Effects of the Invention] As is clear from the above, in the present invention, there is no need to separately prepare alumina raw material powder and glass powder as in the past, and each of the natural minerals mullite, damburite, petalite, and forsterite can be prepared separately. Porcelain is obtained by mixing, molding, and firing the powders. Therefore, the cost of porcelain can be significantly reduced. That is, in the case of conventional alumina-glass porcelain, the raw material cost of alumina powder and glass powder was about 500 yen/Kg, but the raw material cost of the present invention is about 250 yen/Kg, which is lower than the conventional cost of about 200 yen/Kg. It becomes 1/1. Furthermore, according to the present invention, by firing at 1000°C or less,
The bending strength is 2000Kg/cm2 ^or more, and the insulation resistance is 10 ¹³ Ω.
You can get porcelain larger than cm. Therefore, when manufacturing multilayer circuit boards, Au, Ag, Pd, Cu,
It becomes possible to use low melting point metal materials such as Ni. Furthermore, since it is possible to perform firing in a non-oxidizing atmosphere, base metals such as Ni and Cu can be used as electrode materials. According to the second invention of the present application, porcelain that is colored green and has desired characteristics can be obtained by firing at a low temperature of 1000°C or less.

Claims (1)

[Claims] 1. A mixture consisting of 50 to 65 parts by weight of mullite, 25 to 35 parts by weight of damburite, 5 to 20 parts by weight of petalite, and 2 to 8 parts by weight of forsterite is prepared. A method for producing insulating porcelain, which comprises forming a molded body of this mixture and firing the molded body. 2. The method for manufacturing insulating porcelain according to claim 1, wherein forming a molded body of the mixture includes forming a green sheet of the mixture and cutting the green sheet into a desired shape. 3 The firing involves placing the molded body in an oxidizing atmosphere,
3. The method for producing insulating porcelain according to claim 1 or 2, which comprises firing at a temperature in the range of 800°C to 1000°C. 4 The above-mentioned calcination is performed by heating the above-mentioned molded body in an oxidizing atmosphere.
The method for producing insulating porcelain according to claim 1 or 2, which comprises heat treating at a temperature of 500°C to 700°C and firing at a temperature of 800°C to 1000°C in a non-oxidizing atmosphere. . 5 50 to 65 parts by weight of mullite, 25 to 35 parts by weight of damburite, 5 to 20 parts by weight of petalite, 2 to 8 parts by weight of forsterite, and 1 to 5 parts by weight of chromium trioxide. A method for producing insulating porcelain, comprising preparing a mixture, forming a molded body of the mixture, and firing the molded body. 6. The method for manufacturing insulating porcelain according to claim 5, wherein forming a molded body of the mixture includes forming a green sheet of the mixture and cutting the green sheet into a desired shape. 7 The firing involves placing the molded body in an oxidizing atmosphere,
7. The method for producing insulating porcelain according to claim 5 or 6, which comprises firing at a temperature in the range of 800°C to 1000°C. 8 In the firing, the molded body is placed in an oxidizing atmosphere.
The insulating porcelain according to claim 5 or 6, which is heat treated at a temperature in the range of 500°C to 700°C and fired at a temperature in the range of 800°C to 1000°C in a non-oxidizing atmosphere. manufacturing method.