JP2021155244A - Method for producing ceramic substrate and ceramic substrate - Google Patents

Abstract

To provide a method for producing a ceramic substrate capable of easily producing a ceramic substrate with high thermal conductivity and high mechanical strength, and a ceramic substrate.SOLUTION: There is provided a method for producing a ceramic substrate including: a green sheet producing step of producing a green sheet using: alumina having an average raw material particle size of 0.45 μm or more and 0.47 μm or less and standard deviation of the average raw material particle size of 0.14 or more and 0.22 or less; stabilized zirconia having an average raw material particle size of 0.54 μm or more and 0.56 μm or less and standard deviation of the average raw material particle size of 0.13 or more and 0.19 or less; and magnesia; and a firing step of firing the green sheet at a firing temperature of 1504°C or higher and 1590°C or lower, wherein a mass ratio of a mass of the alumina to a mass of the stabilized zirconia is 88.2:11.8 to 90.0:10.0.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for manufacturing a ceramic substrate and a ceramic substrate, and more particularly to a method for manufacturing a ceramic substrate on which electronic components can be mounted and a ceramic substrate.

As electronic components, for example, active elements such as diodes and passive elements such as crystal oscillators are known. In recent years, the output of electronic components has been increasing, and the temperature of electronic components tends to increase accordingly. Since such an increase in temperature may lead to deterioration of electronic components, the ceramic substrate on which the electronic components are mounted is required to have excellent heat dissipation characteristics in order to suppress the increase in temperature of the electronic components. Further, the ceramic substrate is also required to have high mechanical strength from the viewpoint of reliability and the like. However, in general, when the thermal conductivity of the ceramic substrate is increased in order to obtain excellent heat dissipation characteristics, the mechanical strength tends to decrease. Therefore, there is a demand for a ceramic substrate having high thermal conductivity and high mechanical strength.

Patent Document 1 below discloses a method for producing a ceramic substrate using zirconia, silica, and a plurality of types of alumina having different average crystal grain sizes. It is said that the ceramic substrate manufactured by the manufacturing method of Patent Document 1 can have a thermal conductivity of 20 W / m · K or more and a three-point bending strength of 600 MPa or more. Further, according to Patent Document 1, by blasting the surface of the sintered ceramic substrate to set the ratio of monoclinic crystals in the zirconia crystals to a predetermined ratio, the three-point bending strength of the ceramic substrate becomes 650 MPa or more. It is said to get.

Japanese Patent No. 6496021

However, in the production method described in Patent Document 1, as described above, a plurality of types of alumina powders having different average crystal grain sizes must be mixed in a predetermined ratio. Here, when the green sheet is fired in a state where alumina particles of different sizes are not uniformly dispersed, the ceramic substrate has a place where alumina particles having a large crystal grain size are localized and a place where alumina particles having a small crystal grain size are localized. The mechanical strength of the ceramic substrate may be insufficient. Therefore, in the production method described in Patent Document 1, for example, it is necessary to sufficiently lengthen the rotation time of the rotary mill in order to uniformly disperse the plurality of types of alumina powder.

Further, in the ceramic substrate described in Patent Document 1, in order to make the three-point bending strength 650 MPa or more, as described above, the surface of the sintered body is subjected to additional treatment such as blasting. , It is necessary to change the proportion of monoclinic crystals in the zirconia crystals to a predetermined proportion.

As described above, in the method for producing a ceramic substrate of Patent Document 1, it takes a long time to uniformly disperse a plurality of types of alumina, and further addition is added after firing in order to increase the mechanical strength of the ceramic substrate. Since a process is required, it takes time and effort to manufacture a ceramic substrate having high thermal conductivity and high mechanical strength.

Therefore, an object of the present invention is to provide a method for producing a ceramic substrate and a ceramic substrate capable of easily producing a ceramic substrate having high thermal conductivity and high mechanical strength.

In order to achieve the above object, the method for producing a ceramic substrate of the present invention comprises alumina having an average raw material particle size of 0.45 μm or more and 0.47 μm or less and a standard deviation of the average raw material particle size of 0.14 or more and 0.22 or less. , A green sheet preparation using stabilized zirconia having an average raw material particle size of 0.54 μm or more and 0.56 μm or less and a standard deviation of an average raw material particle size of 0.13 or more and 0.19 or less and magnesia. It comprises a step and a firing step of firing the green sheet at a firing temperature of 1504 ° C. or higher and 1590 ° C. or lower, and the mass ratio of the mass of the alumina to the mass of the stabilized zirconia is 88.2: 11.8 to It is 90.0: 10.0.

According to this method for producing a ceramic substrate, alumina having an average crystal grain size of 1.04 μm or more and 1.60 μm or less, stabilized zirconia having an average crystal grain size of 0.39 μm or more and 0.59 μm or less, and magnesia are used. The mass ratio of the mass of the alumina to the mass of the stabilized zirconia is 88.2: 11.8 to 90.0: 10.0, and the content of the magnesia is the mass of the alumina and the stable. A ceramic substrate having a mass ratio of 1.51 parts by mass or more and 1.54 parts by mass or less can be produced with respect to a total mass of 100 parts by mass of zirconia. The three-point bending strength of the ceramic substrate can be 650 MPa or more, and the thermal conductivity can be 20 W / m · K or more. Therefore, according to this method for manufacturing a ceramic substrate, it is possible to manufacture a ceramic substrate having high mechanical strength and high thermal conductivity.

Further, in this method for manufacturing a ceramic substrate, as described above, one kind of alumina having an average raw material particle size of 0.45 μm or more and 0.47 μm or less is used. Therefore, unlike the production method described in Patent Document 1, it is not necessary to mix two types of alumina having different average raw material particle sizes, and for example, the rotation time of the rotary mill can be shortened. Further, unlike the manufacturing method described in Patent Document 1, this ceramic substrate manufacturing method can manufacture a ceramic substrate having a three-point bending strength of 650 MPa or more without performing additional treatment such as blasting after firing. ..

Therefore, according to the method for manufacturing a ceramic substrate of the present invention, a ceramic substrate having high thermal conductivity and high mechanical strength can be manufactured relatively easily.

Further, in the green sheet manufacturing step, the content of magnesia is 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total of the mass of the alumina and the mass of the stabilized zirconia. ..

The above-mentioned ceramic substrate can be produced by setting the content of magnesia as described above, for example.

Further, it is preferable that the average raw material particle size of the magnesia is 0.56 μm or more and 0.58 μm or less, and the standard deviation of the average raw material particle size of the magnesia is 0.16 or more and 0.24 or less.

By using such a magnesia, a ceramic substrate of better quality can be produced.

Further, the average crystal grain size of the particle group consisting of the alumina, the stabilized zirconia, and the magnesia is 0.50 μm or more and 0.60 μm or less, and the standard deviation of the average crystal grain size of the particle group is 0. More preferably, it is 19 or more and 0.29 or less.

If the particle group consisting of alumina, stabilized zirconia, and magnesia is as described above, a ceramic substrate having better quality can be produced.

The firing temperature is preferably 1544 ° C. or higher and 1581 ° C. or lower.

By firing the green sheet at 1544 ° C. or higher and 1581 ° C. or lower, a ceramic substrate having a three-point bending strength of 700 MPa or higher can be produced.

Further, in order to achieve the above object, the ceramic substrate of the present invention contains alumina having an average crystal grain size of 1.04 μm or more and 1.60 μm or less, and stabilized zirconia having an average crystal grain size of 0.39 μm or more and 0.59 μm or less. , Magnesia, and the mass ratio of the mass of the alumina to the mass of the stabilized zirconia is 88.2: 11.8 to 90.0: 10.0, and the content of the magnesia is the alumina. It is characterized in that it is 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total of the mass of the above and the mass of the stabilized zirconia.

A ceramic substrate having such a configuration can be manufactured by the above-mentioned method for manufacturing a ceramic substrate. Further, the three-point bending strength of the ceramic substrate having such a configuration can be 650 MPa or more as described above, and the thermal conductivity can be 20 W / m · K or more. Therefore, this ceramic substrate is easy to manufacture and has high thermal conductivity and high mechanical strength.

Further, in the ceramic substrate, the standard deviation of the average crystal grain size of the alumina is preferably less than 0.43.

By reducing the variation in the average crystal grain size of alumina so that the standard deviation is less than 0.43, the three-point bending strength and thermal conductivity of the ceramic substrate can be effectively increased.

Further, in the ceramic substrate, it is preferable that the average crystal grain size of the alumina is 1.26 μm or more and 1.50 μm or less, and the average crystal grain size of the stabilized zirconia is 0.48 μm or more and 0.57 μm or less.

When the ceramic substrate has such a configuration, the three-point bending strength of the ceramic substrate can be 700 MPa or more.

As described above, according to the present invention, it is possible to provide a method for producing a ceramic substrate and a ceramic substrate capable of easily producing a ceramic substrate having high thermal conductivity and high mechanical strength.

It is a perspective view which shows typically the ceramic substrate which concerns on embodiment of this invention. It is a flowchart which shows the manufacturing method of the ceramic substrate which concerns on embodiment of this invention. It is a graph which shows the relationship between the firing temperature of a ceramic substrate and the three-point bending strength. It is a graph which shows the relationship between the firing temperature of a ceramic substrate and thermal conductivity. It is a graph which shows the relationship between the average crystal grain size of alumina in a ceramic substrate, and three-point bending strength. 6 is a graph showing the relationship between the average crystal grain size of stabilized zirconia and the three-point bending strength in a ceramic substrate. It is a graph which shows the relationship between the average crystal grain size of alumina and thermal conductivity in a ceramic substrate. It is a graph which shows the relationship between the average crystal grain size and thermal conductivity of stabilized zirconia in a ceramic substrate.

Hereinafter, a method for manufacturing a ceramic substrate and a mode for carrying out the ceramic substrate according to the present invention will be illustrated together with the accompanying drawings. The embodiments illustrated below are for facilitating the understanding of the present invention, and are not for limiting the interpretation of the present invention. The present invention can be modified or improved from the following embodiments without departing from the spirit of the present invention. Further, in the present specification, the dimensions of each member may be exaggerated for ease of understanding.

FIG. 1 is a perspective view schematically showing the ceramic substrate 1 in the embodiment. In the ceramic substrate 1, for example, an electronic component can be mounted on at least one of the front surface 1A and the back surface 1B. Such electronic components are not particularly limited, and examples thereof include active elements such as diodes and passive elements such as crystal oscillators.

The ceramic substrate 1 contains alumina having an average crystal grain size of 1.04 μm or more and 1.60 μm or less, stabilized zirconia having an average crystal grain size of 0.39 μm or more and 0.59 μm or less, and magnesia. The mass ratio of the mass to the mass of the stabilized zirconia is 88.2: 11.8 to 90.0: 10.0, and the content of the magnesia is the mass of the alumina and the mass of the stabilized zirconia. It is 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total.

The average crystal grain size of the alumina is not particularly limited as long as it is 1.04 μm or more and 1.60 μm or less, but it is preferably 1.26 μm or more and 1.50 μm or less for the reason described later. The method for calculating the average crystal grain size of alumina in the ceramic substrate 1 is not particularly limited, but in the present embodiment, the front surface 1A or the back surface 1B of the ceramic substrate 1 obtained by a field emission scanning electron microscope (FE-SEM) is used. The image of is binarized by the image processing software "Image-J", and is calculated as the average value of the ferret diameter of each crystal grain calculated.

The stabilized zirconia is a solid solution of a rare earth oxide such as calcia, magnesia, or yttria in zirconia. In the present embodiment, as the stabilized zirconia, zirconia in which yttria is solid-solved may be used. The average crystal grain size of such stabilized zirconia is not particularly limited as long as it is 0.39 μm or more and 0.59 μm or less, but it is preferably 0.48 μm or more and 0.57 μm or less for the reason described later. As described above, the average crystal grain size of stabilized zirconia is approximately half or less the average crystal grain size of alumina. The method for calculating the average crystal grain size of stabilized zirconia in the ceramic substrate 1 is not particularly limited, but in the present embodiment, the surface 1A or the surface 1A of the ceramic substrate 1 obtained by a field emission scanning electron microscope (FE-SEM) or The image on the back surface 1B is binarized by the image processing software "Image-J", and is calculated as the average value of the ferret diameters of the calculated crystal grains.

The mass ratio of the mass of the alumina to the mass of the stabilized zirconia is preferably about 89.1: 10.9. Such a mass ratio may be measured using, for example, an ICP emission spectrophotometer. Here, the measurement accuracy of the ICP emission spectroscopic analyzer is generally 0.5% to 1.0%. Considering this measurement accuracy, the mass ratio of the mass of the alumina to the mass of the stabilized zirconia may be 88.2: 11.8 to 90.0: 10.0.

The magnesia can function as a sintering aid in the method for producing the ceramic substrate 1 described later. In this ceramic substrate 1, as described above, the content of magnesia is 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total of the mass of the alumina and the mass of the stabilized zirconia. ..

In the ceramic substrate 1 having such a configuration, the variation in the average crystal grain size of alumina can be small to the extent that the standard deviation of the average crystal grain size of alumina is less than 0.43. Since the variation in the average crystal grain size of alumina is small as described above, the ceramic substrate 1 can have a high three-point bending strength of 650 MPa or more when the thickness d is approximately 0.2 mm.

Further, in the ceramic substrate 1 having such a configuration, the variation in the average crystal grain size of the stabilized zirconia can be reduced to the extent that the standard deviation of the average crystal grain size of the stabilized zirconia is 0.14 or less. Further, as described above, the average crystal grain size of stabilized zirconia is approximately half or less the average crystal grain size of alumina. As described above, since the size of the stabilized zirconia is small and the variation in the average crystal grain size of the stabilized zirconia is small, the stabilized zirconia can be uniformly dispersed at the triple point of the grain boundary of the alumina. As a result of the stabilized zirconia being uniformly dispersed in the ceramic substrate 1, the ceramic substrate 1 can have a high thermal conductivity of 20 W / m · K or more when the thickness d is approximately 0.2 mm.

Next, a method for manufacturing such a ceramic substrate 1 will be described.

FIG. 2 is a flowchart showing a manufacturing method of the ceramic substrate 1. As shown in FIG. 2, this manufacturing method includes a green sheet manufacturing step SP1 and a firing step SP2. Here, the green sheet is a raw sheet that becomes a ceramic sintered body by firing, and refers to a ceramic substrate before firing.

(Green sheet manufacturing process SP1)
This step is a step of manufacturing the above-mentioned green sheet. In the present embodiment, first, one type of alumina having an average raw material particle size of 0.45 μm or more and 0.47 μm or less and a standard deviation of the average raw material particle size of 0.14 or more and 0.22 or less, and an average raw material particle size are Stabilized zirconia having a standard deviation of 0.54 μm or more and 0.56 μm or less and an average raw material particle size of 0.13 or more and 0.19 or less and magnesia are prepared as raw materials for producing a ceramic substrate. The stabilized zirconia is not particularly limited, but in the present embodiment, it may be stabilized zirconia to which yttria is added.

The average raw material particle size and the standard deviation of the average raw material particle size of magnesia are not particularly limited, but the average raw material particle size is 0.56 μm or more and 0.58 μm or less, and the standard deviation of the average raw material particle size is 0.16 or more. It is preferably 0.24 or less.

The average raw material particle sizes of alumina, stabilized zirconia, and magnesia in this step may be measured by, for example, a laser diffraction / scattering method.

Further, in this step, the mass ratio of the mass of the alumina to the mass of the stabilized zirconia is 88.2: 11.8 to 90.0: 10.0.

The content of magnesia is not particularly limited, but is, for example, 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total of the mass of alumina and the mass of stabilized zirconia. Is preferable.

Further, the average crystal grain size of the particle group composed of the alumina, the stabilized zirconia, and the magnesia is 0.50 μm or more and 0.60 μm or less, and the standard deviation of the average crystal grain size of the particle group is 0. It is preferably 19 or more and 0.29 or less. If the variation in the size of the average crystal grain size of the particle group is as small as this, the particles forming the particle group are likely to be uniformly mixed at the time of preparing the slurry, and the coarse particles are precipitated after the particles are mixed by the rotary mill. Is unlikely to occur, and when the slurry is formed into a sheet, particles are unlikely to be unevenly distributed on a part of the sheet. Therefore, the ceramic substrate 1 having higher quality can be manufactured.

Next, a solvent, a plasticizer, etc., an acrylic resin as a binder, and the like are appropriately mixed with the particle group to prepare a slurry. Then, a green sheet is produced by molding this slurry into a flat sheet by a method such as a doctor blade method or a calendar roll method. The green sheet can also be produced by filling a molding machine with raw material powder and pressure molding.

(Baking process SP2)
This step is a step of firing the green sheet. The firing temperature in this step is not particularly limited as long as it is 1504 ° C. or higher and 1590 ° C. or lower, but it is preferably 1544 ° C. or higher and 1581 ° C. or lower for the reason described later. The firing time is not particularly limited, but may be, for example, one hour.

Through the above steps, alumina having an average crystal grain size of 1.04 μm or more and 1.60 μm or less, stabilized zirconia having an average crystal grain size of 0.39 μm or more and 0.59 μm or less, and magnesia are contained, and the above alumina The mass ratio of the mass to the mass of the stabilized zirconia is 88.2: 11.8 to 90.0: 10.0, and the content of magnesia is the mass of the alumina and the mass of the stabilized zirconia. The above-mentioned ceramic substrate 1 is manufactured, which is 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total.

By the way, when a ceramic substrate is manufactured by mixing a plurality of types of alumina having different average raw material particle sizes, for example, if the rotation time of a rotary mill is short, it is difficult to uniformly disperse large and small alumina. When the green sheet is fired in such a state, in the sintered ceramic substrate, there may be a place where alumina particles having a large crystal grain size are localized or a place where alumina particles having a small crystal grain size are localized. Mechanical strength can be inadequate.

However, in the method for producing a ceramic substrate of the present embodiment, since one type of alumina having an average raw material particle size of 0.45 μm or more and 0.47 μm or less is used, the variation in the size of the raw material particle size of alumina is small. Therefore, it is less necessary to uniformly disperse large and small alumina, and for example, the rotation time of the rotary mill can be shortened. Further, in this method for manufacturing a ceramic substrate, in order to increase the mechanical strength of the ceramic substrate, it is not necessary to additionally perform a blast treatment or the like on the ceramic substrate after the firing step.

As described above, according to the method for manufacturing a ceramic substrate of the present embodiment, it is possible to relatively easily manufacture a ceramic substrate having high thermal conductivity and high mechanical strength.

Next, specific examples of the present invention will be described together with comparative examples, but the present invention is not limited to these examples.

(Example 1)
First, a ceramic substrate was manufactured by the above-mentioned method for manufacturing a ceramic substrate. In the green sheet manufacturing step SP1 of this example, the raw material powders are alumina having an average raw material particle size of 0.46 μm and a standard deviation of 0.19, and an average raw material particle size of 0.55 μm and an average raw material. Stabilized zirconia with a standard deviation of 0.17 particle size and magnesia with an average raw material particle size of 0.57 μm and a standard deviation of 0.21 average raw material particle size were used. Then, alumina, stabilized zirconia, and magnesia were mixed so that the mass ratio of the mass of alumina, the mass of stabilized zirconia, and the mass of magnesia was 87.8: 10.7: 1.5. In this example, the stabilizing component added to the stabilized zirconia is yttria.

Further, an acrylic resin as a binder, a predetermined dispersant, and a predetermined solvent are mixed with a particle group consisting of alumina, stabilized zirconia, and magnesia to form a slurry, and then the slurry is tape-molded by a doctor blade device. Then, a green sheet was prepared.

Next, the produced green sheet was cut into a predetermined shape, and then a firing step SP2 was performed. The firing temperature in this example was 1575 ° C. In this way, a ceramic substrate having a thickness of approximately 0.24 mm was obtained.

Even after the particle group composed of alumina, stabilized zirconia, and magnesia is subjected to the firing step SP2, the mass ratio tends to be substantially the same. Therefore, the mass ratio of alumina, stabilized zirconia, and magnesia in the ceramic substrate which is a sintered body is also approximately 87.8: 10.7: 1.5. Here, when converted so that the total mass of alumina and the mass of stabilized zirconia contained in this ceramic substrate is 100, the mass ratio of the mass of alumina to the mass of stabilized zirconia is approximately 89.1: 10. It becomes 0.9. The content of magnesia contained in this ceramic substrate is approximately 1.52 parts by mass with respect to 100 parts by mass in total of the mass of alumina and the mass of stabilized zirconia. Here, such a mass ratio may be measured by obtaining, for example, an ICP emission spectrophotometer. As described above, the measurement accuracy of the ICP emission spectroscopic analyzer is 0.5% to 1.0%. Therefore, considering this measurement accuracy, the magnesia content is the mass of alumina and the mass of stabilized zirconia. It may be 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total.

Next, the performance evaluation of the ceramic substrate was performed as follows.

From the ceramic substrate, 20 measuring pieces of 12 mm × 50 mm were prepared. Then, these 20 measuring pieces were put into a Tensilon universal material tester RTG-1225 (manufactured by A & D Co., Ltd.), and each measurement was performed under the conditions of a test speed of 0.5 mm / min and an edge span width of 30 mm. The 3-point bending strength (MPa) of the piece was measured. Then, the average of these three-point bending strengths was taken as the three-point bending strength of the ceramic substrate. The results are shown in Table 1 below.

Further, two measuring pieces having a size of 10 mm × 10 mm were prepared from the above ceramic substrate, and the thermal conductivity (W / m · K) of each measuring piece was measured using the thermal constant measuring device LFA457 (manufactured by NETZSCH). Was measured. Then, the average of these thermal conductivitys was taken as the thermal conductivity of the ceramic substrate. The results are shown in Table 1 below.

In addition, crystal particles on the surface of the ceramic substrate were observed using a field emission scanning electron microscope (FE-SEM). The observation magnification was 10000 times, and the observation surface was the surface on the carrier side when tape-molded by the doctor blade device. The image obtained by FE-SEM was binarized with the image processing software "Image-J" and calculated as the standard deviation of the average crystal grain size and the average crystal grain size of each of alumina and stabilized zirconia. The average value and standard deviation of the ferret diameter of each crystal particle were calculated. The results are shown in Table 1 below.

(Comparative Example 1)
In the green sheet manufacturing step SP1, a ceramic substrate was manufactured under the same conditions as in Example 1 except that alumina having an average raw material particle size of 1.1 μm and a standard deviation of 0.56 of the average raw material particle size was further added. bottom. As described above, in this comparative example, the first alumina having the same average raw material particle size as in Example 1 and the standard deviation of the average raw material particle size of 0.19 and the average raw material particle size of 1.1 μm. A second alumina having a standard deviation of 0.56 in average raw material particle size was used as the two types of alumina.

The mass ratio of the first alumina to the second alumina in this comparative example was 80:20. In the green sheet in this comparative example, the mass ratio of the first alumina and the second alumina combined alumina, stabilized zirconia, and magnesia was approximately 87.8: 10.7: 1.5. When converted so that the total mass of alumina and the mass of stabilized zirconia contained in this ceramic substrate is 100, the mass ratio of the mass of alumina to the mass of stabilized zirconia in the ceramic substrate in this comparative example is , Approximately 89.1: 10.9. The content of magnesia in the ceramic substrate was approximately 1.52 parts by mass with respect to 100 parts by mass in total of the mass of alumina and the mass of stabilized zirconia.

The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia were determined by the same method as in Example 1. The results are shown in Table 1 below.

(Comparative Example 2)
In the green sheet manufacturing step SP1, a ceramic substrate was manufactured under the same conditions as in Comparative Example 1 except that the mass ratio of the first alumina to the second alumina was 60:40.

The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia were determined by the same method as in Example 1. The results are shown in Table 1 below.

(Comparative Example 3)
In the green sheet manufacturing step SP1, a ceramic substrate was manufactured under the same conditions as in Comparative Example 1 except that the mass ratio of the first alumina to the second alumina was 40:60.

The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia were determined by the same method as in Example 1. The results are shown in Table 1 below.

(Comparative Example 4)
In the green sheet manufacturing step SP1, a ceramic substrate was manufactured under the same conditions as in Comparative Example 1 except that the mass ratio of the first alumina to the second alumina was set to 20:80.

The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia were determined by the same method as in Example 1. The results are shown in Table 1 below.

As shown in Table 1, it was found that in the ceramic substrates of Comparative Examples 1 to 4 produced from two types of alumina, the three-point bending strength and the thermal conductivity decreased as the mass ratio of the second alumina increased. .. Further, it was found that the three-point bending strength of the ceramic substrates of Comparative Examples 1 to 4 was smaller than 650 MPa. On the other hand, looking at the ceramic substrate of Example 1 produced from one type of alumina, it was found that the three-point bending strength and the thermal conductivity were larger than those of Comparative Examples 1 to 4. The three-point bending strength of the ceramic substrate of Example 1 was 712 MPa, which greatly exceeded 650 MPa. The thermal conductivity of the ceramic substrate of Example 1 was 22.1 W / m · K, which greatly exceeded 20 W / m · K. As described above, the ceramic substrate produced only from the first alumina has higher three-point bending strength and higher than the ceramic substrate produced by mixing two types of alumina, the first alumina and the second alumina. It has been demonstrated to have thermal conductivity.

Further, it was found that the standard deviation of the average crystal grain size of alumina in the ceramic substrate of Example 1 was 0.41, which was smaller than the standard deviation of the average crystal grain size of alumina in the ceramic substrates of Comparative Examples 1 to 4. .. Specifically, the standard deviation of alumina in Example 1 was 0.02 smaller than the standard deviation of alumina of Comparative Example 1 which was the smallest among Comparative Examples 1 to 4. As described above, the ceramic substrate produced only from the first alumina has an average crystal grain size of alumina as compared with the ceramic substrate produced by mixing two types of alumina, the first alumina and the second alumina. It was proved that the variation of was small.

From these points, in the ceramic substrate of Example 1, high three-point bending strength was realized by having a small variation in the average crystal grain size of alumina, and stabilization was achieved by having a small variation in the crystal grain size of alumina. It can be considered that the zirconia crystal grains can be uniformly present at the grain boundaries of the alumina crystal grains, and as a result, high thermal conductivity is realized.

Next, the relationship between the firing temperature and the performance of the ceramic substrate in the case of producing the ceramic substrate using only the first alumina was investigated.

(Example 2)
In this example, after the green sheet preparation step SP1 was performed under the same conditions as in Example 1, the firing step SP2 was performed at a firing temperature of 1550 ° C. The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia obtained as a result were determined by the same method as in Example 1. .. The results are shown in Table 2 below.

(Example 3)
In this example, the green sheet preparation step SP1 was performed under the same conditions as in Example 1, and then the firing step SP2 was performed at a firing temperature of 1525 ° C. The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia obtained as a result were determined by the same method as in Example 1. .. The results are shown in Table 2 below.

(Comparative Example 5)
In this comparative example, the green sheet preparation step SP1 was performed under the same conditions as in Example 1, and then the firing step SP2 was performed at a firing temperature of 1500 ° C. The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia obtained as a result were determined by the same method as in Example 1. .. The results are shown in Table 2 below.

(Comparative Example 6)
In this comparative example, the green sheet preparation step SP1 was performed under the same conditions as in Example 1, and then the firing step SP2 was performed at a firing temperature of 1600 ° C. The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia obtained as a result were determined by the same method as in Example 1. .. The results are shown in Table 2 below.

(Comparative Example 7)
In this comparative example, the green sheet preparation step SP1 was performed under the same conditions as in Example 1, and then the firing step SP2 was performed at a firing temperature of 1625 ° C. The three-point bending strength, thermal conductivity, average crystal grain size / standard deviation of alumina, and average crystal grain size / standard deviation of stabilized zirconia obtained as a result were determined by the same method as in Example 1. .. The results are shown in Table 2 below.

As shown in Table 2 above, according to the ceramic substrates of Examples 1 to 3, it was demonstrated that the three-point bending strength exceeds 650 MPa and the thermal conductivity exceeds 20 W / m · K. It was also found that alumina and stabilized zirconia in the ceramic substrate grew larger as the firing temperature increased at a firing temperature of at least 1500 ° C. or higher and 1625 ° C. or lower.

FIG. 3 is a graph obtained by obtaining the relationship between the firing temperature of the ceramic substrate and the three-point bending strength based on the results in Table 2. Further, FIG. 4 is a graph obtained by obtaining the relationship between the firing temperature of the ceramic substrate and the thermal conductivity based on the results in Table 2.

Stabilization of the first alumina with an average raw material particle size of 0.46 μm and a standard deviation of the average raw material particle size of 0.19, and stabilization with an average raw material particle size of 0.55 μm and an average raw material particle size of 0.17. Zirconia and magnesia having an average raw material particle size of 0.57 μm and an average raw material particle size of 0.21 have a mass ratio of 87 for the mass of the first alumina, the mass of the stabilized zirconia, and the mass of the magnesia. When firing a green sheet prepared by mixing so that the ratio is 8.10.7: 1.5, as shown in FIG. 3, if the firing temperature is 1504 ° C. or higher and 1614 ° C. or lower, the three-point bending strength Was 650 MPa or more, and it was found that the three-point bending strength was 700 MPa or more at a firing temperature of 1544 ° C. or higher and 1581 ° C. or lower. Further, as shown in FIG. 4, it was found that the thermal conductivity of the ceramic substrate was 20 W / m · K or more at a firing temperature of 1500 ° C. or higher and 1590 ° C. or lower.

That is, the mass ratio of the mass of the first alumina to the mass of the stabilized zirconia is approximately 89.1: 10.9, and the content of magnesia is the mass of the first alumina and the stabilized zirconia. By firing a green sheet prepared so as to be approximately 1.52 parts by mass with respect to a total mass of 100 parts by mass at a firing temperature of 1504 ° C. or higher and 1590 ° C. or lower, a three-point bending strength of 650 MPa or higher and heat conduction It was found that a ceramic substrate having a ratio of 20 W / m · K or more can be produced. Further, it was found that, in particular, when the firing temperature is 1544 ° C. or higher and 1581 ° C. or lower, the three-point bending strength can be 700 MPa or higher.

The first alumina having an average raw material particle size of 0.45 μm or more and 0.47 μm or less and a standard deviation of the average raw material particle size of 0.14 or more and 0.22 or less and an average raw material particle size of 0.54 μm or more and 0. Stabilized zirconia having a standard deviation of 56 μm or less and an average raw material particle size of 0.13 or more and 0.19 or less and magnesia have a mass ratio of 88.2: the mass ratio of the mass of the first alumina to the mass of the stabilized zirconia. 11.8 to 90.0: 10.0, and the content of magnesia is 1.51 parts by mass or more with respect to 100 parts by mass in total of the mass of the first alumina and the mass of stabilized zirconia. Even when the green sheet produced by mixing so as to be .54 parts by mass or less is fired at a firing temperature of 1504 ° C. or higher and 1590 ° C. or lower, the three-point bending strength is 650 MPa or higher and the thermal conductivity is 20 W / A ceramic substrate of m · K or more can be manufactured.

FIG. 5 is a graph showing the relationship between the average crystal grain size of alumina in the ceramic substrate and the three-point bending strength based on the results in Table 2. FIG. 6 is a graph showing the relationship between the average crystal grain size of stabilized zirconia and the three-point bending strength in the ceramic substrate based on the results in Table 2. FIG. 7 is a graph obtained by obtaining the relationship between the average crystal grain size of alumina and the thermal conductivity in the ceramic substrate based on the results in Table 2. FIG. 8 is a graph showing the relationship between the average crystal grain size of stabilized zirconia and the thermal conductivity in the ceramic substrate based on the results in Table 2.

As shown in FIGS. 5 and 6, the average crystal grain size of alumina on the ceramic substrate is 1.04 μm or more and 1.92 μm or less, and the average crystal grain size of stabilized zirconia on the ceramic substrate is 0.39 μm or more and 0. It was found that the three-point bending strength can be 650 MPa or more when it is .64 μm or less. When the average crystal grain size of alumina is 1.26 μm or more and 1.50 μm or less and the average crystal grain size of stabilized zirconia is 0.48 μm or more and 0.57 μm or less, the three-point bending strength is 700 MPa or more. It turns out that it can be.

Further, as shown in FIGS. 7 and 8, the average crystal grain size of alumina on the ceramic substrate is 1.00 μm or more and 1.60 μm or less, and the average crystal grain size of stabilized zirconia on the ceramic substrate is 0.38 μm. It was found that the thermal conductivity can be 20 W / m · K or more when it is 0.59 μm or more.

That is, the mass ratio of the mass of alumina to the mass of stabilized zirconia is approximately 89.1: 10.9, and the content of magnesia is 100 parts by mass in total of the mass of alumina and the mass of stabilized zirconia. In a ceramic substrate having approximately 1.52 parts by mass, the average crystal grain size of alumina is 1.04 μm or more and 1.60 μm or less, and the average crystal grain size of stabilized zirconia is 0.39 μm or more and 0.59 μm or less. If so, the three-point bending strength can be 650 MPa or more and the thermal conductivity can be 20 W / m · K or more. Further, in particular, when the average crystal grain size of alumina is 1.26 μm or more and 1.50 μm or less and the average crystal grain size of stabilized zirconia is 0.48 μm or more and 0.57 μm or less, the three-point bending strength is It can be 700 MPa or more.

The mass ratio of the mass of alumina to the mass of stabilized zirconia is 88.2: 11.8 to 90.0: 10.0, and the content of magnesia is the mass of the alumina and the mass of the stabilized zirconia. Even when the total mass is 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass, the average crystal grain size of alumina is 1.04 μm or more and 1.60 μm or less and is stabilized. When the average crystal grain size of zirconia is 0.39 μm or more and 0.59 μm or less, the three-point bending strength and thermal conductivity of the ceramic substrate can be 650 MPa or more and 20 W / m · K or more, respectively.

According to the present invention, there is provided a method for manufacturing a ceramic substrate and a ceramic substrate that can easily manufacture a ceramic substrate having high thermal conductivity and high mechanical strength, and can be used in a field such as an electronic component.

1 ... Ceramic substrate SP1 ... Green sheet manufacturing process SP2 ... Firing process

Claims (8)

Alumina with an average raw material particle size of 0.45 μm or more and 0.47 μm or less and a standard deviation of the average raw material particle size of 0.14 or more and 0.22 or less, and an average raw material particle size of 0.54 μm or more and 0.56 μm or less and an average raw material A green sheet preparation step for producing a green sheet using stabilized zirconia having a standard deviation of 0.13 or more and 0.19 or less and magnesia.
A firing step of firing the green sheet at a firing temperature of 1504 ° C. or higher and 1590 ° C. or lower,
With
A method for producing a ceramic substrate, wherein the mass ratio of the mass of the alumina to the mass of the stabilized zirconia is 88.2: 11.8 to 90.0: 10.0. In the green sheet manufacturing step, the content of the magnesia is 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total of the mass of the alumina and the mass of the stabilized zirconia. The method for manufacturing a ceramic substrate according to claim 1. Claim 1 or 2 characterized in that the average raw material particle size of the magnesia is 0.56 μm or more and 0.58 μm or less, and the standard deviation of the average raw material particle size of the magnesia is 0.16 or more and 0.24 or less. The method for manufacturing a ceramic substrate according to. The average crystal grain size of the particle group consisting of the alumina, the stabilized zirconia, and the magnesia is 0.50 μm or more and 0.60 μm or less, and the standard deviation of the average crystal grain size of the particle group is 0.19 or more. The method for manufacturing a ceramic substrate according to any one of claims 1 to 3, wherein the amount is 0.29 or less. The method for producing a ceramic substrate according to any one of claims 1 to 3, wherein the firing temperature is 1544 ° C. or higher and 1581 ° C. or lower. Alumina with an average crystal grain size of 1.04 μm or more and 1.60 μm or less,
Stabilized zirconia with an average crystal grain size of 0.39 μm or more and 0.59 μm or less,
With Magnesia
Including
The mass ratio of the mass of the alumina to the mass of the stabilized zirconia is 88.2: 11.8 to 90.0: 10.0.
A ceramic substrate having a magnesia content of 1.51 parts by mass or more and 1.54 parts by mass or less with respect to 100 parts by mass in total of the mass of the alumina and the mass of the stabilized zirconia. The ceramic substrate according to claim 6, wherein the standard deviation of the average crystal grain size of the alumina is less than 0.43 in the ceramic substrate. The ceramic substrate is characterized in that the average crystal grain size of the alumina is 1.26 μm or more and 1.50 μm or less, and the average crystal grain size of the stabilized zirconia is 0.48 μm or more and 0.57 μm or less. Item 6. The ceramic substrate according to Item 6.

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