Ceramic Substrate

Abstract

To provide a ceramic substrate having both good thermal conductivity and mechanical strength. The ceramic substrate of the present invention contains aluminum oxide (Al2O3) having an average particle size of 1.31 to 1.55 μm, zirconium dioxide (ZrO2) having an average particle size of 0.65 to 0.75 μm, yttrium oxide (Y2O3), and other components.

Description

[Technical field]

[0001] The present invention relates to a ceramic substrate, its manufacturing method and its use. [Background technology]

[0002] Ceramic compositions and ceramic substrates are widely used as substrates for mounting electronic components via a metal layer. In this case, the ceramic composition functions as an insulating layer on which the metal layer is disposed. The electronic components can then be disposed on the metal layer.

[0003] Ceramic compositions and ceramic substrates used for mounting electronic components are required to have excellent heat dissipation properties, particularly high thermal conductivity. At the same time, it is desirable for the ceramic substrate to have good mechanical strength as a mounting substrate. This is particularly required when the thickness of the ceramic substrate is reduced due to the trend toward miniaturization of electronic components. In other words, a ceramic substrate that has both high thermal conductivity and high mechanical strength is required.

[0004] Known types of ceramic substrates used in this context include alumina substrates containing zirconium oxide (zirconia toughened alumina substrates (ZTA substrates)).

[0005] Such ceramic substrates are described, for example, in EP 2 911 994 B1 (Patent Document 1). This document mentions a metal-ceramic substrate containing Al2O3, ZrO2 and Y2O3, in which the average grain size of the Al2O3 used is 2-8 μm. However, this document is unclear as to whether the grain size of Al2O3 refers to the grain size of the starting material or to the grain size of the sintered material. Also, no method for measuring the grain size is given.

[0006] EP 3786134A1 (Patent Document 2) describes a substrate containing 70 to 95 weight percent alumina particles having a particle size of 1.2 μm to 1.9 μm, and 5 to 30 weight percent zirconia and hafnia. The particle size of the zirconia particles is 0.4 μm to 0.7 μm.

[0007] In addition, US 2021 / 0261473A1 (Patent Document 3) relates to a ceramic substrate in which the grain size of Al2O3 and the grain size of ZrO2 are different. The grain size of the Al2O3 grains is 1.7 to 1.9 μm, and the grain size of the ZrO2 grains is 0.7 to 0.9 μm.

[0008] EP 3 315 476 B1 (Patent Document 4) describes a ceramic substrate containing aluminum oxide crystals with an average crystal grain size of 0.9 to 1.6 μm and zirconium oxide crystals with an average crystal grain size of 0.28 to 0.6 μm.

[0009] The document states that if the average crystal grain size of zirconium oxide exceeds 0.5 μm, the mechanical strength is impaired. If the crystal grain size of aluminum oxide is less than 1.0 μm, high thermal conductivity cannot be obtained. At the same time, if the crystal grain size of aluminum oxide exceeds 1.5 μm, high mechanical strength cannot be obtained. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] European Patent No. 2911994 [Patent Document 2] European Patent Application Publication No. 3786134 [Patent Document 3] US Patent Application Publication No. 2021 / 261473 [Patent Document 4] European Patent No. 3315476 Summary of the Invention [Problem to be solved by the invention]

[0011] In other words, in order to achieve both good thermal conductivity and mechanical strength, it is thought that fine adjustment of the crystal grain size of aluminum oxide and zirconium oxide will be necessary.

[0012] It is therefore an object of the present invention to provide a ceramic substrate that combines good thermal conductivity with mechanical strength. [Means for solving the problem]

[0013] The above object is achieved by a ceramic substrate according to claim 1.

[0014] That is, a ceramic substrate containing the following is provided: -Aluminum oxide (Al2O3) with an average particle size of 1.31-1.55 μm, - zirconium dioxide (ZrO2) with an average particle size of 0.65-0.75 μm, as well as -Yttrium oxide (Y2O3) and silicon oxide (SiO2), and optionally other compounds such as HfO2, TiO2, Cr2O3, Fe2O3, CeO2, Na2O, MgO, K2O, CaO, SrO.

[0015] The ceramic substrate of the present invention is characterized by good thermal stability and good mechanical strength, as will be explained by the data presented later. In particular, this good mechanical strength was unexpected in view of the grain size measured for ZrO2 in the ceramic substrate. Unlike the prior art described above, the mechanical strength is not impaired, and even if the grain size of ZrO2 is more than 0.6 μm, it is possible to increase the mechanical strength to a certain extent.

[0016] The ceramic substrate has a dense crystal arrangement and consists of two phases: ZrO2 grains and Al2O3 grains. The ZrO2 grains are either tetragonal or monoclinic.

[0017] In one embodiment, the ceramic substrate has the following composition: - 85 to 95% by weight (based on the total weight of the ceramic substrate), preferably 88 to 93% by weight, more preferably 89 to 91% by weight, of aluminum oxide (Al2O3) having an average particle size of 1.31 to 1.55 μm (measured by the areimetric method described in the measurement method column), - 4 to 14% by weight (based on the total weight of the ceramic substrate) of zirconium dioxide (ZrO2) having an average particle size of 0.65 to 0.75 μm (measured by the areimetric method described in the measurement method column), preferably 6 to 11% by weight, more preferably 8 to 10% by weight, 0.2 to 0.8 wt. % of yttrium oxide (Y2O3) (based on the total weight of the ceramic substrate), preferably 0.3 to 0.7 wt. %, more preferably 0.4 to 0.6 wt. %, 0.1-0.5 wt. % of silicon oxide (SiO2) (based on the total weight of the ceramic substrate), preferably 0.2-0.4 wt. %, more preferably 0.25-0.35 wt. %, and - less than 0.6% by weight, preferably 0.1-0.45% by weight, more preferably 0.2-0.35% by weight of other compounds (based on the total weight of the ceramic substrate); (The total of each component is always 100% by weight).

[0018] Yttrium oxide is contained as a stabilizer in commercially available zirconium oxide. That is, in the preparation method described later in detail, commercially available yttria-stabilized zirconia is used as a starting material. In addition to yttrium oxide, commercially available zirconium oxide also contains hafnium oxide (HfO2). HfO2 may be present in the range of 1 to 3 parts by mass per 100 parts of zirconium oxide. Yttrium oxide may be present in the zirconium oxide in an amount of 6% by weight or less, preferably about 5 to 5.5% by weight. Preferably, 2.5 to 3.5 mol%, more preferably 3 mol% of Y2O3 (based on the amount of ZrO2) functions as a stabilizer for ZrO2. Commercially available zirconium oxide further contains other components such as aluminum oxide (Al2O3) in an amount of 0.55% by weight or less.

[0019] As mentioned above, the ceramic substrate also contains a sintering aid, in particular silicon dioxide (SiO2). A preferred sintering aid is SiO2. SiO2 may be contained in the ceramic substrate in an amount of 0.5% by weight or less, preferably 0.35% by weight or less.

[0020] In one embodiment, the ceramic substrate contains: - 85 to 95% by weight (based on the total weight of the ceramic substrate) of aluminum oxide (Al2O3) having an average grain size of 1.31 to 1.55 μm; - 4 to 14% by weight (based on the total weight of the ceramic substrate) of zirconium dioxide (ZrO2) having an average particle size of 0.65 to 0.75 μm, 0.2 to 0.8% by weight (based on the total weight of the ceramic substrate) of yttrium oxide (Y2O3); 0.1 to 0.5 wt. % silicon oxide (SiO2) (based on the total weight of the ceramic substrate); and - Less than 0.6% by weight of other compounds (based on the total weight of the ceramic substrate) (The total of each component is always 100% by weight).

[0021] In a further embodiment, the ceramic substrate contains: - 88 to 93% by weight (based on the total weight of the ceramic substrate) of aluminum oxide (Al2O3) having an average grain size of 1.31 to 1.55 μm; - 6 to 11% by weight (based on the total weight of the ceramic substrate) of zirconium dioxide (ZrO2) having an average grain size of 0.65 to 0.75 μm; 0.3 to 0.7% by weight (based on the total weight of the ceramic substrate) of yttrium oxide (Y2O3); 0.2 to 0.4 wt. % silicon oxide (SiO2) (based on the total weight of the ceramic substrate); and - 0.1 to 0.45% by weight of other compounds (based on the total weight of the ceramic substrate) (The total of each component is always 100% by weight).

[0022] In yet another embodiment, the ceramic substrate contains: - 89 to 91% by weight (based on the total weight of the ceramic substrate) of aluminum oxide (Al2O3) having an average grain size of 1.31 to 1.55 μm; - 8 to 10% by weight (based on the total weight of the ceramic substrate) of zirconium dioxide (ZrO2) having an average particle size of 0.65 to 0.75 μm, 0.4 to 0.6% by weight (based on the total weight of the ceramic substrate) of yttrium oxide (Y2O3); - 0.25 to 0.35 wt. % silicon oxide (SiO2) (based on the total weight of the ceramic substrate); and - 0.2 to 0.35% by weight of other compounds (based on the total weight of the ceramic substrate) (The total of each component is always 100% by weight).

[0023] In one embodiment, the ceramic substrate has a flexural strength (measured according to ASTM C1499-15) of more than 620 MPa, preferably more than 650 MPa, more preferably more than 670 MPa, even more preferably more than 680 MPa, for example 690 MPa. The flexural strength may be in the range of 620 to 800 MPa, preferably in the range of 630 to 760 MPa, even more preferably in the range of 650 to 730 MPa.

[0024] In another embodiment, the ceramic substrate has a thermal conductivity (measured according to ISO 18755:2005 at 20° C.) of greater than 20 W / m·K, preferably greater than 22 W / m·K, even more preferably greater than 24 W / m·K. The thermal conductivity may be in the range of 20-40 W / m·K, preferably 22-35 W / m·K, more preferably 23-30 W / m·K, even more preferably 24-27 W / m·K.

[0025] In yet another embodiment, the ceramic substrate has an elastic modulus or Young's modulus, measured by the grind sonic method (described in the Examples section), of greater than 310 GPa, preferably greater than 350 GPa, and even more preferably greater than 360 GPa. The Young's modulus may be in the range of 310 to 400 GPa, preferably in the range of 330 to 390 GPa, and more preferably in the range of 350 to 380 GPa.

[0026] In addition, the ceramic substrate has a fracture toughness K (measured in accordance with the IF method described in the Examples section). Ic Niihara is 3 to 5MPa m 1 / 2 , preferably 3.5 to 4.5 MPam 1 / 2 , more preferably 3.8 to 4.2 MPa m 1 / 2 The Vickers hardness of the present ceramic substrate is preferably 1500 to 2000 HV, more preferably 1600 to 1900 HV, more preferably 1700 to 1850 HV, and even more preferably 1750 to 1830 HV.

[0027] The ceramic substrate also suitably has a surface roughness Ra (measured in accordance with DIN EN ISO 4288) of less than 0.5 μm, preferably less than 0.4 μm, more preferably less than 0.2 μm, for example 0.19 μm.

[0028] The bulk density of this ceramic substrate (measured according to DIN 993-1 / ISO18754) is 3.5 g / cm 3 More than 3.95 g / cm 3 More preferably still, 4 g / cm 3 Ultra, for example 4.0-4.1g / cm 3 It is.

[0029] In another embodiment, the ceramic substrate has a dielectric breakdown strength (measured according to DIN EN 60243 ff at 20° C.) of more than 20 kV / mm, preferably more than 25 kV / mm, more preferably more than 30 kV / mm. The dielectric breakdown strength may be in the range of 20-40 kV / mm, preferably in the range of 25-35 kV / mm, more preferably 28-33 kV / mm.

[0030] The specific heat capacity of the ceramic substrate (measured by a DSC apparatus described in the Examples section) is greater than 620 J / gK, preferably greater than 650 J / gK, more preferably greater than 670 J / gK. The specific heat capacity may be in the range of 620 to 750 J / gK, preferably in the range of 650 to 720 J / gK, more preferably 670 to 710 J / gK.

[0031] The thermal expansion coefficient CTE of this ceramic substrate (measured with a thermal dilatometer described in the Examples section) is 7×10 -6 / K, 300-600℃, 8×10 -6 / K, 8.6×10 at 600-900℃ -6 / K or more.

[0032] In one preferred embodiment, the ceramic may have the following properties: -Flexural strength in the range of 630 to 760 MPa; -Thermal conductivity, which can be in the range of 22 to 35 W / m·K; -The modulus of elasticity can be in the range of 330 to 390 GPa; - a dielectric breakdown strength that may be in the range of 25 to 35 kV / mm; and Specific heat capacity which can be in the range of -650 to 720 J / gK.

[0033] In a most preferred embodiment, the ceramic may have the following properties: -Flexural strength in the range of 650 to 730 MPa; -Thermal conductivity, which can be in the range of 23 to 30 W / m·K; -The modulus of elasticity can be in the range of 350 to 380 GPa; - a dielectric breakdown strength that may be in the range of 28 to 33 kV / mm; and Specific heat capacity which can be in the range of -670 to 710 J / gK.

[0034] The ceramic substrate may be manufactured by a method comprising the steps of: - preparing a first mixture of at least one aluminium oxide of a first type having a particle size (d50) between 0.1 and 0.8 μm, preferably between 0.3 and 0.6 μm, and at least one aluminium oxide of a second type having a particle size (d50) between 0.9 and 1.7 μm, preferably between 1.0 and 1.5 μm, - preparing a second mixture of at least one yttria-stabilized zirconium oxide of a first type having a particle size (d50) between 0.2 and 0.5 μm, preferably with a d50 between 0.25 and 0.35 μm, and at least one yttria-stabilized zirconium oxide of a second type having a particle size (d50) between 0.8 and 1.4 μm, preferably with a d50 between 0.9 and 1.25 μm, - combining said mixture of aluminium oxides with said mixture of zirconium oxides and, optionally, with other additives, in particular SiO2 as a sintering aid, and dispersing these mixtures in a grinder, - adding a binder, such as polyvinyl alcohol (PVA), polyvinyl butyral (PVB), to the mixture after dispersion of aluminum oxide and zirconium oxide, - forming the mixture after dispersion of aluminum oxide, zirconium oxide and binder into a desired form, for example a film, a sheet, etc.; and - sintering the shaped mixture, thereby providing the ceramic substrate.

[0035] In a preferred embodiment of the method, the first grade Al2O3 may have a particle size d50 of 0.3-0.6 μm and a d90 of less than 3.0 μm, preferably less than 2.0 μm, and the second grade Al2O3 may have a particle size d50 of 1.0-1.5 μm and a d90 of less than 4.0 μm, preferably less than 3.6 μm.

[0036] In another preferred embodiment of the method, the first grade ZrO2 may have a particle size d50 of 0.25-0.35 μm and a d98 of less than 2.0 μm, and the second grade ZrO2 may have a particle size d50 of 0.9-1.25 μm and a d80 of 1.5-2.2 μm.

[0037] In one preferred embodiment of the method, as starting material for aluminum oxide, a first mixture is provided containing: 42.5 to 47.5% by weight, preferably 44 to 46.5% by weight, more preferably 44.5 to 45.5% by weight of at least one aluminium oxide of a first type with a particle size (d50) between 0.1 and 0.8 μm, preferably with a d50 between 0.3 and 0.6 μm, and 42.5 to 47.5% by weight, preferably 44 to 46.5% by weight, more preferably 44.5 to 45.5% by weight of at least one aluminum oxide of a second type having a particle size (d50) of 0.9 to 1.7 μm, preferably 1.0 to 1.5 μm.

[0038] That is, two types of aluminum oxide, preferably with different particle sizes, are used as starting materials in approximately a 1:1 weight ratio, ie, about 50% by weight of each type.

[0039] In another preferred embodiment of the method, a second mixture is provided as starting material for zirconium oxide, containing: 2.8-9.8 wt. %, 4.2-7.7 wt. %, 5.6-7 wt. % of at least one zirconium oxide of a first type with a particle size (d50) of 0.2-0.5 μm, preferably with a d50 of 0.25-0.35 μm, 1.2-4.2 wt. %, 1.8-3.3 wt. %, 2.4-3 wt. % of at least one zirconium oxide of a second type with a particle size (d50) of 0.8-1.4 μm, preferably with a d50 of 0.9-1.25 μm.

[0040] That is, it is preferable to use as starting materials about 70% by weight of at least one zirconium oxide of a first type having a particle size d50 of 0.2-0.5 μm, preferably d50 of 0.25-0.35 μm, and further about 30% by weight of at least one zirconium oxide of a second type having a particle size d50 of 0.8-1.4 μm, preferably d50 of 0.9-1.25 μm.

[0041] In a further embodiment of the method, a sintering aid such as SiO2 and an organic compound such as a binder (e.g., PVA, PVB, etc.) are added to the Al2O3 / ZrO2 mixture.

[0042] Then, the powder mixture of Al2O3 / (Y2O3-containing)ZrO2 / sintering aid is put into a pulverizer together with a solvent such as water or an organic solvent, preferably a solvent containing a dispersant, to obtain a dispersion.

[0043] In the next molding step, the slurry is molded into a green sheet or green film by a doctor blade method, or the slurry is spray-dried with a spray dryer to prepare granules, from which a green sheet is molded by a powder press molding method or a roller compactor method.

[0044] Then, the green compact may be obtained by processing the outer shape with a metal mold or a laser. The green sheet may be used as the green compact as is, and the outer shape may be processed with a laser after firing. In addition, in consideration of mass production, it is preferable to use a multi-piece green compact.

[0045] The sintering step is carried out in a heating furnace, and the sintering temperature is preferably 1400 to 1700°C.

[0046] The ceramic substrate of the present invention can be used in electronic devices. Such electronic devices can include a ceramic substrate as a support having a metal layer disposed on one or both sides. Electronic components can be provided on the metal layer.

[0047] The electronic components provided on the metal layer of the ceramic substrate may be used in semiconductor elements such as insulated gate bipolar transistor (IGBT) elements, intelligent power module (IPM) elements, metal oxide semiconductor field effect transistor (MOSFET) elements, LED elements, free wheel diode (FWD) elements, high power transistor (GTR) elements, and Schottky barrier diodes (SBD). The electronic components may also be used in heating elements of dye-sublimation thermal printer heads and thermal inkjet printer heads. The electronic components may also be used in Peltier elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] The present invention will now be described in detail with reference to examples. EXAMPLES

[0049] The following examples are included to demonstrate certain aspects and embodiments of the claimed invention, however, those of ordinary skill in the art will appreciate that the following descriptions are illustrative only and should not be construed as limiting the invention in any way.

[0050] I. Synthesis Incoming testing is performed on the starting materials ZrO2, Al2O3 and SiO2. Two different grades each of Al2O3 and ZrO2 are used to achieve the particle size distribution shown in the final product.

[0051] The bulk preparation (slurry) is done in a grinding mill. The bulk preparation consists of mixing the raw materials, i.e. ceramic starting materials and organic compounds. The slurry is poured into a mold to form a ceramic green film. The green film is cut to the specified dimensions. The ceramic film is sintered at 1400-1700°C.

[0052] II. Analysis (Grain size: Application of area measurement method to sintered ceramic substrate) Next, the area measurement method used to measure the average crystal grain size of alumina and zirconia will be described. First, the surface of the ceramic substrate 1 is mirror-finished and subjected to heat treatment within a temperature range of 50 to 100°C lower than the firing temperature. Then, this heat-treated surface is used as the measurement target surface and photographed at a magnification of 5000 times using an SEM. Next, the photographed image data is analyzed using image analysis software (for example, WinROOF (Mitani Shoji Co., Ltd.)). As a result, data on the crystal grain size of each of alumina and zirconia present in the image data can be obtained.

[0053] Ceramic substrates should contain crystals with a grain size of less than 0.05 mm, but image analysis software only targets crystals with a grain size of 0.05 mm or more. In addition, when using image analysis software such as the one mentioned above, alumina crystal grains and zirconia crystal grains have different colors, making it possible to measure them separately.

[0054] The average value of the equivalent circle diameters of each alumina crystal grain calculated from the area of ​​each alumina crystal grain is defined as the average crystal grain size of alumina, and the average value of the equivalent circle diameters of each zirconia crystal grain calculated from the area of ​​each zirconia crystal grain is defined as the average crystal grain size of zirconia.

[0055] The standard deviation of the crystal grain size of alumina can be determined from the data of the crystal grain size of alumina obtained by image analysis software using the same method as that used for measuring the average crystal grain size described above.

[0056] (Measurement of fracture toughness (KIc value) of ceramic substrates according to the IF method based on the evaluation by Niihara and Anstis) The KIc value was determined by the IF method described in AG Evans, EA Charles, J. Am. Ceram. Soc. 1976, 56, 371-372 and GR Anstis, P. Chantikul, et al., J. Am. Ceram. Soc. 1981, 64, 533-538.

[0057] Briefly, substrates were prepared, and samples were removed from each substrate, embedded in Clarosit, and ground and polished.

[0058] A number of Vickers indentations were then made on each substrate to produce at least five (but typically no more than ten) indentations of sufficient quality. By sufficient quality, we mean clearly identifiable cracks that run away from the edge of the indentation (clear and relatively straight cracks with relatively clearly identifiable ends that do not branch out) and no major cracks visible on the indentation. To ensure that obvious cracks without major cracks form in the indentation, it was first necessary to determine an appropriate indentation load. If the indentation load is too low, no cracks will appear. If the indentation load is too high, the substrate will break or the indentation will have so many chips that it will be impossible to evaluate. If the indentation load is too low, either no cracks will appear or the cracks will be short.

[0059] K Ic The evaluation, i.e. the calculation, of the values ​​was carried out according to the formula of Niihara and Anstis:

[0060]

number

[0061] (In the formula, KIC, Niihara = fracture toughness (MPa√m), HH = Vickers hardness value (MPa), EE = modulus of elasticity (MPa), c = length of crack + half the diagonal of the hardness indentation (m) aa = half the diagonal of the hardness indentation (m).

[0062]

number

[0063] (In the formula, KIC,Anstis = fracture toughness (MPa√m); HH = Vickers hardness value (MPa), EE = modulus of elasticity (MPa), c = length of crack + half the diagonal of the hardness indentation (m) aa = half the diagonal of the hardness indentation (m).

[0064] For the elastic modulus, a literature value (360 GPa) was used. Hardness values ​​were measured and printed directly at the time of application of the hardness indentation. Crack length and indentation diagonal were measured directly after each hardness indentation on the testing rig.

[0065] The hardness and KIc values ​​of each sample measured are shown in Table 1 below. The average and standard deviation are shown for each. As mentioned above, five or more hardness indentations were measured per sample to obtain the average value.

[0066] [Table 1]

[0067] (Specific heat capacity) Specific heat capacity, or heat capacity, is a measurable physical quantity that corresponds to the ratio of heat input to an object to the resulting change in temperature, and is given by:

[0068]

number

[0069] Specific heat is the amount of heat required to raise the temperature of 1 gram of a substance by 1°C.

[0070] DSC measurements are carried out in accordance with DIN 51007 and ISO 11357-1.

[0071] [Functioning principle of heat flux DSC] The DSC measuring cell consists of a furnace and an integrated sensor, with a mounting area corresponding to the sample and reference containers. The sensor surface is connected to a thermocouple or is part of the thermocouple itself. This allows recording both the temperature difference between the sample and reference side (DSC signal) and the absolute temperature of the sample or reference side. When the DSC measuring cell is heated, the reference side (usually the empty container) usually heats up faster than the sample side, in terms of the heat capacity cp of the sample. That is, the reference temperature (TR) rises a little earlier than the sample temperature (TP). If the heating rate is constant, both curves behave parallel to each other until the sample reacts. In this case, the sample starts to melt at t1. During the melting process, the temperature of the sample does not change, while the temperature of the reference side continues to rise linearly without this influence. After the melting is completed at time t2, the sample temperature also rises again and resumes a linear slope.

[0072] The difference signal (ΔT) between these two temperature curves is used. In the middle of the curve, a peak of the difference formation occurs. This peak represents the endothermic melting process. Depending on whether the reference temperature is subtracted from the sample temperature during the difference formation or the sample temperature is subtracted from the reference temperature, the resulting peak can point either upwards or downwards in the graph. The area of ​​the peak is related to the heat content (enthalpy (J / g)) that is converted.

[0073] (Young's modulus) The measurement setup consists of a Grindsonic connected to a microphone or piezo sensor, an appropriate clapper, and a special sample holder with supports for each sample shape. The setup is further connected to a PC to record the measurements. The elasticity of a material means that it deforms under an external load, but quickly returns to its original state when the load is removed. This strain is linearly proportional to the applied load (Hooke's law). The quotient of the strain and the load is the proportionality coefficient known as the Young's modulus of the material.

[0074] (Coefficient of Thermal Expansion CTE) The linear thermal expansion of the samples is measured as a function of temperature using a Netzsch measuring device. Thermal expansion is a measure of the change in volume of an object with respect to a change in temperature. The measurements are performed according to the manufacturer's specification DIL402 Expedis Select & Supreme - NETZSCH Analyzing & Testing (netzsch-thermal-analysis.com).

[0075] The following table summarizes the parameter values ​​measured by each standard method:

[0076] [Table 2]

[0077] The following Tables 3 and 4 summarize several examples of the present invention (Examples IE1 and IE2 of the present invention) and their respective characteristics.

[0078] Table 3 presents the type and amount of starting materials for each example of the present invention. The first grade Al2O3 has a particle size d50 of 0.5 μm and a d90 of 2.0 μm, the second grade Al2O3 has a particle size d50 of 1.3 μm and a d90 of 3.2 μm. The first grade ZrO2 has a particle size d50 of 0.3-0.32 μm and a d90 of 0.60 μm, and the second grade ZrO2 has a particle size d50 of 1.17 μm and a d80 of 2.06 μm.

[0079] Another additive used is SiO2 as a sintering aid.

[0080] [Table 3]

[0081] Other additives may be added, but the total of all components must equal 100% by weight.

[0082] The resulting ceramic substrate contains Al2O3, ZrO2, Y2O3 and SiO2. Other components of the ceramic substrate include Na2O, MgO, K2O, CaO, TiO2, Cr2O3, Fe2O3, SrO, CeO.

[0083] Table 4 summarizes the mechanical, thermal and electrical properties of each of the examples of the present invention in Table 3.

[0084] As can be seen from Table 4, the bending strength reaches a high value of more than 650 MPa and even more than 680 MPa, and the thermal conductivity is 24 to 25 W / (m K). In other words, each of the examples of the present invention has both excellent mechanical strength and good thermal conductivity.

[0085] [Table 4]

[0086] Furthermore, Table 5 shows the effect of the specific ZrO2 particle size and amount of ZrO2 employed in each of Examples IE1 and IE2 of the present invention in comparison with Comparative Examples CE1 and CE2.

[0087] Comparative Examples CE1 and CE2 were obtained according to the general procedure described above, specifically, the required amounts of Al2O3, ZrO2 and SiO2 powders were mixed, crushed, granulated and compacted and sintered.

[0088] [Table 5]

[0089] As can be seen from CE2, when using smaller grain size of ZrO2, 0.49μm, the bending strength of the final ceramic reaches 640MPa. On the other hand, even higher bending strengths of over 650MPa and over 680MPa were detected when using ZrO2 with grain size of 0.65 (IE1) and 0.72 (IE2). Thus, even with ZrO2 grain size above 0.6μm, the mechanical strength is not compromised, and even it can be improved to some extent, which is an unexpected effect contrary to the prior art.

Claims

1. - Aluminum oxide (Al) with an average particle size of 1.31 to 1.55 μm (measured by the area measurement method described in the measurement method column) ２ O ３ )and, - Zirconium dioxide (ZrO) with an average particle size of 0.65 to 0.75 μm (measured by the area measurement method described in the measurement method column) ２ )and, - yttrium oxide (Y ２ O ３ ), silicon oxide (SiO ２ ) and other ingredients, A ceramic substrate comprising:

2. The ceramic substrate according to claim 1, - Aluminum oxide (Al) with an average particle size of 1.31 to 1.55 μm (measured by the area measurement method described in the measurement method column) ２ O ３ 85 to 95 wt. % (based on the total weight of the ceramic substrate) of - Zirconium dioxide (ZrO) with an average particle size of 0.65 to 0.75 μm (measured by the area measurement method described in the measurement method column) ２ 4 to 14 wt. % (based on the total weight of the ceramic substrate); - yttrium oxide (Y ２ O ３ 0.2 to 0.8 wt. % (based on the total weight of the ceramic substrate); -silicon oxide (SiO ２ 0.1 to 0.5 wt. % (based on the total weight of the ceramic substrate); - less than 0.6% by weight of other components (based on the total weight of the ceramic substrate); and the total of each component is necessarily 100% by weight.

3. 10. The ceramic substrate of claim 1, wherein the ceramic substrate has a flexural strength (measured in accordance with ASTM C1499-15) of greater than 620 MPa.

4. 10. The ceramic substrate of claim 1, characterized in that the ceramic substrate has a thermal conductivity (measured according to ISO 18755:2005 at 20°C) of more than 20 W / mK.

5. 2. The ceramic substrate according to claim 1, wherein the ceramic substrate has an elastic modulus (Young's modulus) of more than 310 GPa.

6. 2. The ceramic substrate according to claim 1, wherein the fracture toughness K (measured in accordance with the IF method) Ｉｃ A ceramic substrate having a Niihara of 3 to 5 MPa m1 / 2.

7. 2. The ceramic substrate according to claim 1, characterized in that the surface roughness Ra (measured in accordance with DIN EN ISO 4288) is less than 0.5 μm.

8. 2. A method for manufacturing a ceramic substrate according to claim 1, comprising: - providing a first mixture of at least one aluminium oxide of a first type having a particle size (d50) between 0.1 and 0.8 μm and at least one aluminium oxide of a second type having a particle size (d50) between 0.9 and 1.7 μm; - providing a second mixture of at least one yttria-stabilized zirconium oxide of a first type having a particle size (d50) of 0.2 to 0.5 μm and at least one yttria-stabilized zirconium oxide of a second type having a particle size (d50) of 0.8 to 1.4 μm; - combining said mixture of aluminium oxides and said mixture of zirconium oxides, and optionally other additives, and dispersing these mixtures in a grinder; - adding a binder to said mixture after dispersion of aluminum oxide and zirconium oxide; - forming the mixture of aluminum oxide, zirconium oxide and binder into the desired shape; - sintering the mixture after shaping, thereby providing the ceramic substrate; A manufacturing method comprising:

9. The manufacturing method according to claim 8, The first mixture comprises: 42.5 to 47.5% by weight of at least one aluminum oxide of a first type with a particle size (d50) of 0.1 to 0.8 μm, and - 42.5 to 47.5% by weight of at least one aluminum oxide of a second type with a particle size (d50) of 0.9 to 1.7 μm, A method for producing a composition comprising the steps of:

10. The manufacturing method according to claim 8, the second mixture comprising: 2.8 to 9.8% by weight of at least one zirconium oxide of a first type with a particle size d50 between 0.2 and 0.5 μm, and - 1.2 to 4.2% by weight of at least one zirconium oxide of a second type with a particle size d50 between 0.8 and 1.4 μm, A method for producing a composition comprising the steps of:

11. 9. The method according to claim 8, wherein SiO ２ and an organic compound are added.

12. 9. The method according to claim 8, wherein the sintering step is carried out at a temperature of 1400 to 1700°C.

13. A method for using the ceramic substrate according to claim 1 in an electronic device.

14. An electronic device comprising the ceramic substrate according to claim 1.