Method for inspecting spreading powder application amount and method for producing ceramic substrate using the same

Abstract

To provide a method for inspecting a spreading powder application amount.SOLUTION: A method for inspecting a spreading powder application amount includes: a first measurement step of measuring a volume of a spreading powder application layer on a ceramic member with respect to the ceramic member having the spreading powder application layer to which spreading powder is applied, by using a laser microscope from a surface direction of the ceramic member; a step of subtracting a predetermined offset value from the volume of the spreading powder application layer obtained in the first measurement step; a step of integrating from a value obtained by subtracting the offset value up to a maximum height value; and a step of performing the step of subtracting the offset value and the step of integrating at a plurality of locations.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments described below generally relate to a method for inspecting the amount of applied powder and a method for manufacturing a ceramic substrate using the same. [Background technology]

[0002] Ceramic substrates are used for circuit boards on which semiconductor elements are mounted. Various ceramic substrates are used, including silicon nitride substrates, aluminum nitride substrates, aluminum oxide substrates, zirconium oxide substrates, and aluzirconia substrates. Aluzirconia substrates are a mixture of zirconium oxide and aluminum oxide. The manufacturing process of a ceramic substrate includes a raw material mixing process, a molding process, a debinding process, and a sintering process. The raw material mixing process is a process of mixing raw material powder with an organic binder to prepare a raw material paste. The molding process is a process of preparing a sheet-shaped molded body from the raw material paste. The debinding process is a process of removing the binder from the sheet-shaped molded body. The sintering process is a process of sintering the debound sheet-shaped molded body. The sheet-shaped molded body is cut to a predetermined size and then subjected to the debinding and sintering processes. In the sintering process, the sheet-shaped molded bodies are stacked to improve manufacturing efficiency. A laying powder is used to stack the sheet-shaped molded bodies. The use of the laying powder can prevent the sheet-shaped molded bodies from bonding together. For example, in Japanese Patent No. 5339214 (Patent Document 1), the particle size and application amount of the spreading powder are controlled. By controlling the application amount of the spreading powder, waviness on the surface of the ceramic substrate is reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5339214 Summary of the Invention [Problem to be solved by the invention]

[0004] As in Patent Document 1, by controlling the amount of applied powder, it is possible to reduce waviness on the surface of the ceramic substrate. However, as the processing volume increases, the yield rate decreases. When the cause of this problem was investigated, it was found to be due to variations in the amount of applied powder on the ceramic molded body. Ceramic green bodies are formed using sheet molding methods such as the doctor blade method. Microscopic irregularities are formed on the surface of ceramic green bodies. The powder deposits in accordance with these microscopic irregularities. This causes variations in the amount of powder applied to the ceramic green body. There was no measurement method to grasp this variation, and it was not possible to fully grasp the extent of the variation. The embodiment is intended to address such a problem and provides a method for inspecting the amount of applied powder. [Means for solving the problem]

[0005] In one embodiment, the method for inspecting the amount of applied powder is characterized by comprising a first measurement step of measuring the volume of the applied powder layer on a ceramic component having an applied powder layer using a laser microscope from the surface direction of the ceramic molded body, a step of subtracting a predetermined offset value from the volume of the applied powder layer obtained in the first measurement step, a step of integrating from the value obtained by subtracting the offset value to the maximum height value, and a step of performing the subtraction of the offset value and the integration step at multiple locations. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 10 is a diagram showing an example of a method for applying bedding powder. [Figure 2] FIG. 4 is a diagram showing an example of a first measurement step according to the embodiment. [Figure 3] FIG. 4 is a diagram showing an example of an offset region according to the embodiment. [Figure 4] 1 is a diagram showing an example of a ceramic substrate according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] In one embodiment, the method for inspecting the amount of applied powder is characterized by comprising a first measurement step of measuring the volume of the applied powder layer on a ceramic component having an applied powder layer using a laser microscope from the surface direction of the ceramic molded body, a step of subtracting a predetermined offset value from the volume of the applied powder layer obtained in the first measurement step, a step of integrating from the value obtained by subtracting the offset value to the maximum height value, and a step of performing the subtraction of the offset value and the integration step at multiple locations. The ceramic member having a powder-coated layer is either a ceramic substrate or a ceramic molded body. A ceramic substrate is a ceramic sintered body. The following explanation will be given using a ceramic molded body as an example. Figure 1 shows an example of a method for applying a spreading powder. In the figure, reference numeral 1 denotes a ceramic molded body, reference numeral 2 denotes a spreading powder injection nozzle, and reference numeral 3 denotes the spreading powder. The spreading powder injection nozzle is sometimes simply called an injection nozzle. Figure 1 shows a method in which spreading powder 3 is sprayed from injection nozzle 2 to apply the spreading powder 3 onto ceramic molded body 1. The ceramic molded body 1 may also be a long sheet molded body. A ceramic molded body 1 produced by the doctor blade method becomes a long sheet molded body. Mass productivity can be improved by applying the spreading powder while transporting the long sheet molded body. The method for producing a ceramic molded body having a spreading powder coating layer coated with spreading powder is not limited to the method using an injection nozzle, but may also be a method using a paintbrush or other brush.

[0008] The above steps prepare a ceramic compact with a powder coating layer. Next, a first measurement step is performed to measure the volume of the powder coating layer on the ceramic compact from the surface direction of the ceramic compact using a laser microscope. Figure 2 shows an example of the first measurement step. In the figure, symbol 1 denotes the ceramic compact, symbol 3 denotes the powder, symbol 4 denotes the powder coating layer, and symbol 5 denotes the laser microscope. A spreading powder coating layer 4 is formed on the surface of the ceramic formed body 1. The surface direction of the ceramic formed body 1 is a direction that is approximately perpendicular to the surface of the ceramic formed body 1. The approximately perpendicular direction is within a range of 80° to 100°. Furthermore, it is preferable that measurement with the laser microscope 5 be performed from the perpendicular (90°) direction. The volume of the spreading powder coating layer 4 can be determined from the three-dimensional image obtained by the laser microscope 5.

[0009] The laser microscope used should be a Keyence VK-X1000 series microscope or one with equivalent or better performance. The analysis software used should be the multi-file analysis application included with the VK-X1000 series. A 2mm x 2.6mm measurement field is recommended. While the measurement field is optional, a narrow field of view may not provide an average value for the amount of powder applied. A wide field of view may allow for an average value to be determined, but may require more measurements.

[0010] Next, a step is performed in which a predetermined offset value is subtracted from the volume of the powder coating layer obtained in the first measurement step. The offset value is a correction value that offsets deviations from the standard in order to remove errors that uniformly occur in measurements. The concept of offset value is shown in Figure 3. In the figure, reference numeral 1 denotes the ceramic compact, reference numeral 4 denotes the powder coating layer, reference numeral 6 denotes the offset region, and reference numeral 7 denotes the integral range. The offset region 6 is a region where at least a portion of the spreading powder 3 is embedded in the ceramic formed body 1. The ceramic formed body 1 is formed by mixing ceramic powder with a binder, etc. The ceramic formed body 1 is flexible. In the process of applying the spreading powder 3, a portion of the spreading powder 3 that is in direct contact with the surface of the ceramic formed body 1 sinks into the ceramic formed body 1. The offset region 6 extends to the highest point of the spreading powder 3 embedded in the surface of the ceramic formed body 1. The volume of the offset region 6 is the offset value.

[0011] Next, a step of integrating the value obtained by subtracting the offset value up to the maximum height value is performed. The maximum height value is the thickest point of the powder coating layer 4. The powder 3 in the offset region 6 is embedded in the ceramic molding 1. For this reason, the function of the powder 3 in the offset region 6 as a release agent is reduced. In order for the powder to function as a release agent, some of the powder is not embedded in the ceramic molding 1. The powder that is not embedded in the ceramic molding 1 becomes the integral region 7.

[0012] Next, the step of subtracting the offset value and the step of integrating are performed at a plurality of locations. By performing the steps at a plurality of locations, the integral region 7 present on the ceramic formed body 1 can be grasped. When measuring multiple times, it is preferable to measure at points at least 1 cm apart. 2 It is preferable to measure at five or more locations per (10 cm x 10 cm). The four corners and the center are the five locations that must be measured. When measuring at six or more locations, any location can be measured. There is no particular upper limit to the number of measurements, but 20 or less is preferable. If the number of measurements is more than 20, there is a possibility that no further effect can be obtained. Therefore, it is recommended to measure at least 100 cm of the surface area of ​​the ceramic molded body 1. 2 For each 10cm x 10cm area, measurements are preferably taken at 5 to 20 locations, and more preferably at 5 to 10 locations. The measurement field of view is preferably 2mm x 2.6mm. For a 10cm x 10cm ceramic molded body, it is preferable to observe the four corners and the center with a measurement field of view of 2mm x 2.6mm.

[0013] The maximum height value is preferably determined by the following method. The maximum height value is measuring the surface roughness of the ceramic member to obtain a first surface roughness value; A step of applying a spreading powder to a ceramic member to form a spreading powder coating layer, and a step of measuring the surface roughness of the spreading powder coating layer to obtain a second surface roughness value; a step of measuring the surface of the ceramic member having the powder coating layer with a laser microscope, correcting the shape of the second surface roughness value, and obtaining a leveled value; The maximum value of the smoothed values ​​obtained by the above is used as the maximum height value. The first surface roughness value is the surface roughness of the ceramic member. When it is desired to inspect the amount of powder applied to a ceramic molded body, the ceramic member is the ceramic molded body. When it is desired to inspect the amount of powder applied to a ceramic substrate (sintered body), the ceramic member is the ceramic substrate. Furthermore, a standard sample may be used for the ceramic molded body or the ceramic substrate. If necessary, the ceramic substrate may be cleaned to prepare a standard sample. Examples of cleaning methods include water cleaning and ultrasonic cleaning. In other words, the step of measuring the surface roughness of the ceramic member to obtain the first surface roughness value may be performed each time, or a value measured in advance using a standard sample may be used.

[0014] The surface roughness of a ceramic member is preferably one selected from Ra (arithmetic mean roughness), Rzjis (ten-point mean roughness), Sa (arithmetic mean height), and S10z (ten-point area height). Ra is shown as a line (two-dimensional). Ra is shown as a surface (three-dimensional) representing Sa. Rzjis is shown as a line (two-dimensional). Rzjis is shown as a surface (three-dimensional) representing S10z. The surface roughness of a ceramic member is preferably an average value. This is because it serves as a representative value for a standard sample. For example, Rz (maximum height, formerly Ry or Rmax) is an absolute value indicating the maximum height. Ry may also be used, but partial variations make it unsuitable for use as the first surface roughness value. For this reason, the first surface roughness value is preferably an average value, such as Ra or Rzjis. Ra and Rzjis are measured according to JIS-B-0601 (2013). The measurement method for Sa is based on JIS-B-0681 (2018), and S10z is based on ISO25178 (2012). The surface of the ceramic member to be measured is measured at any 5 to 20 locations, and the average value is defined as the first surface roughness value, which is also the offset value.

[0015] Next, the process of applying a laying powder to a ceramic molded body to form a laying powder coating layer and the process of measuring the surface roughness of the laying powder coating layer to obtain a second surface roughness value are performed. The process of applying a laying powder to a ceramic molded body to form a laying powder coating layer is as described above. Next, the surface roughness of the laying powder coating layer is measured. The surface roughness of the laying powder coating layer 4 is the same parameter as that used to determine the first surface roughness value. For example, if Ra is used as the first surface roughness value, the surface roughness of the laying powder coating layer is also measured as Ra. Similarly, if Rzjis is used as the first surface roughness value, the surface roughness of the laying powder coating layer is also measured as Rzjis. The surface roughness of the laying powder coating layer is defined as the second surface roughness value. The second surface roughness value is also measured using a laser surface roughness meter. If the laser microscope has a surface roughness meter function, it may also be used. The number of measurements of the surface roughness of the laying powder coating layer is the same as the number of measurements used to determine the first surface roughness value. For example, if the first surface roughness value is the average value of measurements taken at five locations, the second surface roughness value is also the average value of measurements taken at five locations. The number of measurements is the same when measuring the amount of powder applied to a ceramic substrate having a powder-applied layer. In this way, the surface roughness of the powder-applied layer is measured, and the average value is taken as the second surface roughness value. The reference length of one location for measuring the surface roughness value is 2 mm or more. This means measuring 2 mm or more within a single measurement field of view of 2 mm x 2.6 mm.

[0016] Next, the surface of the ceramic component having the powder coating layer is measured using a laser microscope, and the second surface roughness value is corrected for shape to obtain a smoothed value. The surface of the ceramic component having the powder coating layer refers to the surface of the ceramic substrate itself or a standard sample on which the powder coating layer is formed. The surface of the ceramic component has minute irregularities and undulations. The thickness of the powder coating layer 4 differs between convex and concave portions. For example, the integral region 7 is thinner in convex portions. This may result in areas lacking the necessary powder. For this reason, it is effective to perform shape correction. Shape correction can be one of the following: waviness correction (sometimes called waviness removal), secondary spherical correction, spherical correction, or plane tilt correction. These shape corrections are functions built into laser microscopes. The multi-file analysis application included with the VK-X1000 series mentioned above allows selection as a type of surface shape correction. Of the various shape corrections, plane tilt correction is preferable. Plane tilt correction is a correction that converts the obtained surface roughness data into a plane. The surface of a ceramic component has minute irregularities and undulations. By performing shape correction, it is possible to measure the amount of powder to be applied while taking into account the irregularities and undulations of the ceramic component surface.

[0017] The second surface roughness value after shape correction is called the leveled value. The process to obtain the leveled value is performed multiple times, and the maximum value of the obtained leveled values ​​is defined as the maximum height value. It is preferable that the number of processes to obtain the leveled value is the same as the number of processes to obtain the first surface roughness value. For example, if the first surface roughness value is the average value of measurements taken at five locations, the leveled value is also measured five times, and the maximum value is defined as the maximum height value. It is preferable to use the maximum height value thus obtained to perform a process of integrating from the value obtained by subtracting the offset value to the maximum height value. In other words, integration is performed in the range of the maximum height value minus the offset value in the thickness direction of the powder coating layer 4. This makes it possible to measure the volume of the powder not buried in the ceramic molded body 1. Similarly, it is possible to measure the volume of the powder not buried in the ceramic substrate. The above-described method for inspecting the amount of applied laying powder makes it possible to inspect whether the amount of applied laying powder is appropriate. The appropriate amount of applied laying powder can be set arbitrarily. Furthermore, by using a laser microscope, the inspection time can be shortened. Furthermore, since it is a non-destructive inspection, no waste of products is generated. Furthermore, 100% inspection is possible. Therefore, the yield of ceramic substrates can be improved. The amount of powder applied on the ceramic compact was 3 × 10 6 μm 3Over 2×10 7 μm 3 The amount of powder applied on the ceramic sintered body is preferably within the range of 5×10 6 μm 3 Over 2×10 7 μm 3 The following range is preferable: It is preferable to set this range as an appropriate amount. Furthermore, the measurement time for one location can be reduced to 2 minutes or less, or even 1 minute 30 seconds or less. The time required to process the measured data can be reduced to 3 minutes or less, or even 30 seconds or less. Data processing can be automated using a computer to reduce the time required.

[0018] Furthermore, it is preferable to have a step of removing a portion of the applied laying powder when it is determined that the amount of applied laying powder is too much as a result of the step of subtracting a predetermined offset value from the thickness of the laying powder applied layer obtained in the first measurement step. This indicates that when too much laying powder is applied, the excess laying powder should be removed. If too much laying powder is applied, the surface unevenness of the ceramic component after sintering may become large. Furthermore, the step of removing a portion of the applied laying powder can be performed using an air blower, a paintbrush, or a brush. Furthermore, after performing the step of removing a portion of the applied laying powder, it is preferable to perform the method of inspecting the amount of applied laying powder again according to the embodiment. Furthermore, the step of removing a portion of the applied laying powder and the method of inspecting the amount of applied laying powder according to the embodiment may be performed alternately. This means that excess laying powder is removed little by little to inspect whether the amount is appropriate. Since the method of inspecting the amount of applied laying powder according to the embodiment is a non-destructive inspection, such a method can be applied.

[0019] Furthermore, if the amount of applied laying powder is determined to be insufficient as a result of subtracting a predetermined offset value from the thickness of the laid-powder layer obtained in the first measurement step, it is preferable to further apply the laying powder. This indicates that the step of applying the laying powder again is performed when the amount of applied laying powder is insufficient. If the amount of applied laying powder is insufficient, the ceramic substrates may bond together after sintering. Therefore, if the amount of applied laying powder is determined to be insufficient, it is preferable to apply the laying powder again. Furthermore, after applying the laying powder again, it is preferable to perform the method for inspecting the amount of applied laying powder according to the embodiment to confirm whether the amount of applied laying powder is appropriate. It is also possible to alternate between additional application of laying powder and the method for inspecting the amount of applied laying powder. This indicates that additional application of laying powder is performed little by little. Since the method for inspecting the amount of applied laying powder according to the embodiment is a non-destructive inspection, such a method can be applied.

[0020] The method for manufacturing a ceramic substrate according to the embodiment is characterized by including a step of sintering a ceramic molded body having a layer of applied powder whose amount of applied powder has been determined to be within the appropriate range by carrying out the method for inspecting the amount of applied powder according to the embodiment. The method for inspecting the amount of applied powder according to the embodiment is carried out, and the ceramic body whose amount of applied powder is determined to be appropriate is sintered. Since the amount of applied powder is appropriate, it is possible to reduce surface irregularities on the ceramic substrate and suppress bonding between ceramic substrates. This can improve the yield of ceramic substrates. An example of a ceramic substrate is shown in Figure 4. In the figure, reference numeral 8 denotes a ceramic substrate. While Figure 4 shows an example in which the top surface is rectangular, the shape is not limited to this. The ceramic substrate can be shaped in a variety of ways, such as circular (including oval), square, triangular, or polygonal. Screw holes or the like may also be formed as needed.

[0021] The ceramic molded body 1 may be primarily composed of one selected from silicon nitride, aluminum nitride, aluminum oxide, zirconium oxide, and silicon carbide. The primary component is the component that is most prevalent among the components that make up a ceramic substrate. For example, a ceramic molded body 1 primarily composed of silicon nitride becomes a silicon nitride substrate after sintering. A ceramic molded body 1 primarily composed of aluminum oxide becomes an aluminum oxide substrate after sintering. In addition, when two or more materials selected from silicon nitride, aluminum nitride, aluminum oxide, zirconium oxide, and silicon carbide are mixed, the material with the greater amount of the component is used as the main component. For example, an alu-zir substrate is a mixture of aluminum oxide and zirconium oxide. If the alu-zir substrate contains aluminum oxide as the most abundant component, it becomes an aluminum oxide substrate. The thickness of the ceramic substrate is preferably in the range of 0.1 mm to 3 mm.

[0022] The ceramic molded body 1 can be manufactured by a doctor blade method, die molding, cold isostatic pressing (CIP), injection molding, etc. As will be described later, the doctor blade method is preferred when manufacturing a ceramic substrate. The doctor blade method can produce a long sheet-shaped ceramic molded body, which can improve mass productivity. A long sheet-shaped ceramic molded body is also sometimes called a green sheet. Furthermore, the ceramic formed body 1 is subjected to a degreasing process as necessary. In other words, a degreased body that has been subjected to a degreasing process is also included in the ceramic formed body 1. The degreasing process may be performed before or after applying the spreading powder.

[0023] The spreading powder 3 may be one or more selected from boron nitride, zirconium oxide, aluminum oxide, and aluminum nitride. The spreading powder is applied to the surface of the ceramic molded body 1 to form a spreading powder coating layer 4. The spreading powder 4 is preferably boron nitride. As will be described later, the ceramic sintered body is fired at approximately 1600 to 2000°C. Boron nitride is difficult to bond with the ceramic sintered body even in a high-temperature environment. There are various types of boron nitride, including hexagonal, cubic, and rhombohedral crystals. Of these, hexagonal boron nitride is preferred. Hexagonal boron nitride is sometimes abbreviated as h-BN.

[0024] Furthermore, it is preferable that the spreading powder has an average particle size of 20 μm or less. By reducing the average particle size, it becomes easier to form a spreading powder coating layer 4 with a uniform thickness on the surface of the ceramic molded body 1. If the average particle size is larger than 20 μm, the spreading powder layer 5 will become non-uniform, which may have an adverse effect on the surface properties of the ceramic sintered body. For this reason, it is preferable that the average particle size of the spreading powder is 20 μm or less. It is also preferable that the average particle size of the spreading powder is 10 μm or less, and more preferably 6 μm or less. There is no particular lower limit for the average particle size of the spreading powder, but it is preferably 2 μm or more. If the average particle size is less than 2 μm, it may be difficult to handle.

[0025] Furthermore, the ceramic molded body is preferably a silicon nitride molded body, and the underlying powder is preferably boron nitride. Furthermore, the ceramic substrate is preferably a silicon nitride substrate. Silicon nitride powders used as raw materials include α-type and β-type. Most α-type silicon nitride powders have an aspect ratio of less than 2. Most β-type silicon nitride powders have an aspect ratio of 2 or more. By carrying out the sintering process, the α-type silicon nitride powder undergoes grain growth to β-type. The grains grow into β-type silicon nitride crystal particles with a large aspect ratio. This grain growth can result in increased surface irregularities. By using the method for inspecting the amount of applied underlying powder according to the embodiment, the amount of applied underlying powder can be optimized. Therefore, ceramic substrates can be obtained with a high yield.

[0026] Furthermore, the sintered ceramic substrate is subjected to a straightening process as necessary. The straightening process involves heating the ceramic substrate while applying surface pressure. Since the amount of powder on the surface of the ceramic substrate 8 is appropriate, it is possible to prevent the powder from falling off during transport to the straightening process. For this reason, it is also effective to check the volume of the layer of powder present on the surface of the ceramic substrate using the method for inspecting the amount of powder applied according to the embodiment. The warping correction process is a process in which surface pressure and heat are applied. If the amount of powder applied is appropriate, it is possible to control the surface irregularities of the ceramic substrate during the warping correction process and prevent the ceramic substrates from sticking together. Furthermore, the warping correction process requires the application of surface pressure. If the powder falls off, it may cause clogging of the mechanism that applies pressure. This also contributes to improving the yield of ceramic substrates. Furthermore, when the volume of the layer of powder coating present on the surface of the ceramic substrate is examined by the method for inspecting the amount of powder coating according to the embodiment, if the amount of powder coating is too much, a step of removing the powder coating is carried out. If the amount of powder coating is insufficient, a step of applying the powder coating may be carried out. As described above, the method for inspecting the amount of applied powder according to the embodiment can improve the yield of ceramic substrates. Furthermore, the method for inspecting the amount of applied powder according to the embodiment can be used to measure the amount of applied powder on either or both of the surface of a ceramic molded body or the surface of a ceramic substrate. This method is particularly effective for ceramic substrates with a thickness of 0.1 mm or more and 3 mm or less, and even 0.1 mm or more and 1 mm or less. Surface irregularities in thin substrates affect insulation properties, etc. In other words, the method for inspecting the amount of applied powder according to the embodiment is suitable for manufacturing ceramic substrates with a thickness of 0.1 mm or more and 3 mm or less.

[0027] (Example) (Examples 1 to 8, Comparative Examples 1 to 3) Silicon nitride was used as the ceramic compact, and boron nitride powder was used as the base powder. The silicon nitride was a sheet-like compact produced by the doctor blade method. The boron nitride powder had an average particle size of 20 μm or less. The sheet-like molded body was coated with a layer of bedding powder while being conveyed. The bedding powder was mixed with a solvent and applied by spraying. Through this process, a silicon nitride molded body having a layer of bedding powder was produced. Next, a silicon nitride molded body and a silicon nitride substrate were prepared as standard samples for setting the offset value. The surface roughness of the silicon nitride substrate used as the standard sample is shown in Table 1. The surface roughness of the standard sample (silicon nitride substrate) is the offset value (first surface roughness). The offset value was measured using a laser microscope (VK-X1000 series). The measurement field was 2 mm x 2.6 mm. Measurements were taken at five points in a 10 cm x 10 cm area: the four corners and the center. The measurement field at one point was 2.6 mm x 2 mm, and the average value of the five measurement fields was used. The measurement length for surface roughness was 2 mm.

[0028] [Table 1]

[0029] Next, the volume of the powder coating layer of the silicon nitride molded body having the powder coating layer was measured using a laser microscope. The laser microscope was used to measure from a direction 90° to the surface of the silicon nitride molded body. The results are shown in Table 2.

[0030] [Table 2]

[0031] Next, the surface roughness of the silicon nitride molded body with the powder coating layer was measured. The surface roughness of the powder coating layer (second surface roughness) was measured using a laser surface roughness meter. Measurements were taken at five locations: the four corners and the center of a 10 cm x 10 cm area of ​​the powder coating layer. The measurement field was 2.6 mm x 2 mm, and the average value of the five locations was shown. The laser surface roughness meter used a function built into the laser microscope. Shape correction was also performed using the plane tilt correction built into the laser microscope. The results are shown in Table 3.

[0032] [Table 3]

[0033] Next, 15 silicon nitride molded bodies having the powder coating layers of Examples 1 to 4 were stacked and subjected to a sintering process. The sintering process was carried out by placing a weight on the stack (15 stacked) of silicon nitride molded bodies having the powder coating layers. The sintering temperature was in the range of 1700°C or higher and 1900°C or lower. A silicon nitride substrate (sintered body) was obtained by this process. The amount of powder spread on the surface of the silicon nitride substrate was measured. The standard sample shown in Table 4 was used for measuring the amount of powder spread.

[0034] [Table 4]

[0035] Next, the surface roughness of the silicon nitride substrate having the powder coating layer was measured. The surface roughness of the powder coating layer (second surface roughness) was measured using a laser surface roughness meter. Measurements were taken at five locations: the four corners and the center of a 10 cm x 10 cm area of ​​the powder coating layer. The field of view for each measurement was 2.6 mm x 2 mm, and the average value was shown. The laser surface roughness meter used a function provided in the laser microscope. Shape correction was also performed using the plane tilt correction provided in the laser microscope. In Examples 1 to 4, only the amount of powder coating on the silicon nitride molded body was measured. The results are shown in Table 5.

[0036] [Table 5]

[0037] As shown in Table 5, Examples 1 to 4 were tested for the amount of powder applied to the surface of a silicon nitride molded body, and Examples 5 to 8 were tested for both the amount of powder applied to the surface of a silicon nitride molded body and the amount of powder applied to the surface of a silicon nitride substrate. The amount of powder applied to the silicon nitride compact is 3 x 10 6 μm 3 Over 2×10 7 μm 3 The amount of powder applied to the silicon nitride substrate was determined to be within the following range: 6μm 3 Over 2×10 7 μm 3 The amount was judged to be appropriate within the following range. Amounts judged to be appropriate were marked with a "◯". Amounts that were outside the appropriate range were marked with an "X", and amounts that were not measured were marked with a "-". In Comparative Example 1, the amount of powder applied to the molded body and the substrate surface was not measured. In Comparative Example 2, the amount of powder applied to the silicon nitride molded body was 2×10 7 μm 3 In addition, the amount of powder applied to the silicon nitride substrate in Comparative Example 3 was 2×10 7 μm 3 The results of the test on the amount of powder applied are shown in Table 6.

[0038] [Table 6]

[0039] All of the examples were within the range. If the amount of applied powder was found to be insufficient in the inspection process, additional powder was added. Similarly, if the amount of applied powder was found to be excessive in the inspection process, the powder was removed by air blowing. 1000 silicon nitride substrates were produced for each type. The obtained silicon nitride substrates were subjected to a warping correction process. In the warping correction process, the substrates were heated at a temperature between 500°C and 1200°C while applying a surface pressure. The silicon nitride substrates were all 0.32 mm thick. The yield after the straightening process was measured. The presence or absence of clogging of the powder during the straightening process was also checked. The yield was checked by the percentage of silicon nitride substrates with a maximum surface irregularity of 50 μm or less after the straightening process, and by whether the substrates could be easily peeled apart. The maximum irregularity was measured using a 3D shape measuring device. The ease of peeling the substrates apart was also measured by the percentage of substrates that could be peeled apart with air blowing or with little force. A percentage of good products of 99% to 100% was marked with ◎, 95% to 99% was marked with ◯, and less than 95% was marked with ×. The percentages are by number. In addition, regarding whether or not clogging of the powder occurred during the recurving process, if clogging did not occur even once in the production of 1,000 sheets, it was rated as "none", and if clogging occurred at least once, it was rated as "yes". The results are shown in Table 7.

[0040] [Table 7]

[0041] As can be seen from the table, the yield of the examples was good, at 95% or more. Furthermore, by inspecting the amount of powder applied on both the surface of the molded body and the surface of the substrate, as in Examples 5 to 8, the yield was improved. Furthermore, since the amount of powder applied in the examples was within the appropriate range, clogging during the warping correction process could be prevented. In contrast, in Comparative Example 1, the amount of applied powder was not inspected. As a result, variations in the amount of applied powder occurred, resulting in a decrease in yield. Furthermore, in Comparative Example 2, a large amount of applied powder was applied to the surface of the molded body, and in Comparative Example 3, a large amount of applied powder was applied to the surface of the substrate. In these cases, the resulting substrate had large irregularities, resulting in a decrease in yield. Furthermore, since the amount of applied powder was large in Comparative Examples 2 and 3, clogging frequently occurred during the warping correction process. Therefore, it is clear that the inspection method according to the embodiment functions effectively.

[0042] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. Modifications of these embodiments are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0043] 1...Ceramic molding 2...Spread powder spray nozzle 3…Bedding powder 4...Flour coating layer 5...Laser microscope 6...Offset area 7…integral region 8...Ceramic substrate

Claims

1. a step of applying a first coating powder to the ceramic compact; a step of measuring the surface roughness of the ceramic molded body to which the spreading powder has been applied and obtaining an offset value; a step of applying a second coating powder to the ceramic compact; a first measuring step of measuring the volume of the laying powder coating layer on the ceramic molded body using a laser microscope from the surface direction of the ceramic molded body, the ceramic molded body having the laying powder coating layer applied thereto; a step of converting the volume measured in the first measuring step into a thickness; subtracting the offset value from the thickness calculated from the first measurement; A step of integrating the value from the subtraction of the offset value to the maximum height value as an integration range to calculate the powder application volume; subtracting the offset value; performing the integrating step at a plurality of locations; A method for inspecting the amount of powder applied.

2. 2. The method for inspecting the amount of applied spreading powder according to claim 1, wherein the first step of applying spreading powder comprises measuring the surface roughness of the ceramic formed body after cleaning with an air blower.

3. The maximum height value is measuring the surface roughness of the ceramic formed body to obtain a first surface roughness value; a step of applying a laying powder to the ceramic molded body to form a laying powder coating layer; and a step of measuring the surface roughness of the laying powder coating layer to obtain a second surface roughness value. a step of measuring the surface of the ceramic molded body having the spreading powder coating layer with a laser microscope, correcting the shape of the second surface roughness value, and obtaining a leveled value; 3. The method for inspecting the amount of powder application according to claim 1, wherein the maximum value of the leveled values ​​obtained by the above step is set as the maximum height value.

4. a step of removing a portion of the applied powder when it is determined that the amount of applied powder is too much as a result of the step of inspecting the amount of applied powder according to claim 1; A method for inspecting the amount of powder applied, comprising:

5. As a result of the step of inspecting the amount of applied powder according to claim 1, if it is determined that the amount of applied powder is small, a step of applying the powder again; A method for inspecting the amount of powder applied, comprising:

6. 3. The method for inspecting the amount of applied spreading powder according to claim 1, wherein the spreading powder is boron nitride and the ceramic molded body is a silicon nitride molded body.

7. A method for manufacturing a ceramic substrate, comprising the step of sintering a ceramic molded body having a powder coating layer whose powder coating amount has been certified as being within the appropriate range, after the step of performing the powder coating amount inspection method described in claim 3.

8. A method for manufacturing a ceramic substrate, comprising a step of sintering a ceramic molded body having a powder coating layer whose powder coating amount has been certified as being within the appropriate range, after a step of performing the powder coating amount inspection method described in claim 6.

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