阅读说明：本技术 复合氧化锆粉体、氮化铝陶瓷基板及其制备方法与应用 (Composite zirconia powder, aluminum nitride ceramic substrate, and preparation method and application thereof ) 是由 杨雪蛟 付苒 谭毅成 于 2021-07-15 设计创作，主要内容包括：本发明涉及一种复合氧化锆粉体、氮化铝陶瓷基板及其制备方法与应用。该复合氧化锆粉体包括内核及包裹于内核的壳层,内核为纳米氧化锆,壳层为氧化铝及氮化铝的混合物。通过在纳米氧化锆表面包覆氧化铝/氮化铝壳层,避免氧化锆粉体作为增韧剂加入氮化铝陶瓷时,氧化锆反应生成杂质而导致含量减少,达不到预期的增韧效果,因此能够保证氧化锆的增韧效果,同时由于氧化锆表面包覆氧化铝/氮化铝壳层结构,氧化锆颗粒不易发生团聚,因而能够保证陶瓷制品性能均一性。采用上述复合氧化锆粉体作为增韧剂得到的氮化铝陶瓷基板在保证热导率满足半导体封装基板使用要求的情况下,具有优良的力学性能。(The invention relates to a composite zirconia powder, an aluminum nitride ceramic substrate, and a preparation method and application thereof. The composite zirconia powder comprises a core and a shell layer wrapped on the core, wherein the core is nano zirconia, and the shell layer is a mixture of alumina and aluminum nitride. By coating the alumina/aluminum nitride shell layer on the surface of the nano zirconia, the problem that when zirconia powder is used as a toughening agent and added into aluminum nitride ceramic, the content of the zirconia is reduced due to the generation of impurities by the reaction of zirconia, and the expected toughening effect cannot be achieved is solved, so that the toughening effect of the zirconia can be ensured. The aluminum nitride ceramic substrate obtained by using the composite zirconia powder as the toughening agent has excellent mechanical properties under the condition of ensuring that the thermal conductivity meets the use requirement of a semiconductor packaging substrate.)

1. The composite zirconia powder is characterized by comprising a core and a shell layer wrapping the core, wherein the core is nano zirconia, and the shell layer is a mixture of alumina and aluminum nitride.

2. The composite zirconia powder of claim 1, wherein the mass ratio of the inner core to the shell is 1: (0.4-2.7).

3. The composite zirconia powder of claim 1, wherein the particle size of the composite zirconia powder is 60nm to 130 nm.

4. The composite zirconia powder of any one of claims 1 to 3, wherein the radial dimension of the core is 50nm to 100nm, and the thickness of the shell is 10nm to 30 nm.

5. The method for preparing the composite zirconia powder according to any one of claims 1 to 4, comprising the steps of:

uniformly mixing nano zirconia powder, an alumina precursor, active carbon, a dispersing agent and water to obtain a suspension;

adding a pH regulator into the suspension, regulating the pH of the suspension to 7-8, standing, filtering and drying to obtain first mixed powder;

calcining the first mixed powder at 1200-1600 ℃ in a nitrogen atmosphere to obtain second mixed powder;

and calcining the second mixed powder at 600-700 ℃ in an air atmosphere to obtain the composite zirconia powder.

6. The method for preparing the composite zirconia powder of claim 5, wherein the alumina precursor is selected from anhydrous AlCl₃、Al(NO₃)₃And Al₂(SO₄)₃One kind of (1).

7. The method for preparing the composite zirconia powder according to claim 5, wherein the mass ratio of the nano zirconia powder, the alumina precursor, the activated carbon, the dispersant and the water is 1: (3-15): (0.2-3): (0.01-0.5): (2-15).

8. The method for preparing the composite zirconia powder according to claim 5, wherein the calcination time of the first mixed powder at 1200-1600 ℃ is 2-10 hours;

and/or the second mixed powder is calcined at the temperature of 600-700 ℃ for 1-5 hours.

9. The aluminum nitride ceramic substrate is characterized by comprising the following preparation raw materials in parts by mass:

70-95 parts of aluminum nitride powder;

3-25 parts of a toughening agent; and

1-10 parts of sintering aid;

wherein the toughening agent is the composite zirconia powder of any one of claims 1 to 3.

10. The aluminum nitride ceramic substrate according to claim 9, wherein the sintering aid is at least one selected from the group consisting of rare earth metal oxides, alkaline earth metal oxides, and metal fluorides.

11. The aluminum nitride ceramic substrate according to claim 9 or 10, wherein the aluminum nitride powder is 80 to 92 parts by mass, the toughening agent is 5 to 15 parts by mass, and the sintering aid is 3 to 5 parts by mass.

12. A preparation method of an aluminum nitride ceramic substrate is characterized by comprising the following steps:

mixing the preparation raw materials of the aluminum nitride ceramic substrate according to any one of claims 9 to 11 to prepare a casting slurry;

preparing a casting green body by casting;

and removing the glue and sintering to obtain the aluminum nitride ceramic substrate.

13. Use of the aluminum nitride ceramic substrate according to any one of claims 9 to 11 as a substrate for semiconductor packages.

14. An electronic device, wherein a chip of the electronic device comprises the aluminum nitride ceramic substrate according to any one of claims 9 to 11.

Technical Field

The invention relates to the technical field of ceramics, in particular to composite zirconia powder, an aluminum nitride ceramic substrate, and a preparation method and application thereof.

Background

The semiconductor package substrate is used for carrying electronic elements and connecting wires between the electronic elements, and is a substrate with good insulation property. With the development of semiconductors along the direction of high power, high frequency and integration, the requirements for materials of semiconductor package substrates are increasing, such as good insulation and breakdown resistance, high thermal conductivity, thermal expansion coefficient matching with the package materials, low dielectric constant and low dielectric loss.

The ceramic substrate materials for semiconductor packaging which are commonly used at present mainly include: beryllium oxide base plate, aluminium nitride base plate and silicon nitride base plate. Among them, beryllium oxide substrates have high thermal conductivity, but the powder thereof is toxic, and causes poisoning and environmental pollution. The alumina ceramic substrate is the most mature ceramic substrate material in the current manufacturing and processing technology, has the advantages of low dielectric loss, low temperature dependence of electrical property, higher mechanical strength and good chemical stability, but can only be applied to low-end or low-power devices at present due to low thermal conductivity and high thermal expansion coefficient. The silicon nitride ceramic substrate has a plurality of excellent performances such as high hardness, high strength, small thermal expansion coefficient, small high-temperature creep, good oxidation resistance, good hot corrosion performance, small friction coefficient and the like, but the preparation process conditions are complex and harsh, the requirements on equipment are extremely high, the yield is low and the production cost is high. The aluminum nitride ceramic substrate has high thermal conductivity which can reach more than 150W/(m.K), and the thermal expansion coefficient is (3.8-4.4) multiplied by 10^-6The temperature per DEG C is better matched with the thermal expansion coefficient of semiconductor chip materials such as silicon, silicon carbide and the like, but the mechanical property of the aluminum nitride ceramic is betterPoor bending strength of only 300MPa, and is very easy to damage under the use environment of heavy current and high temperature, thereby causing adverse effect on the service life of the semiconductor.

Disclosure of Invention

Therefore, it is necessary to provide an aluminum nitride ceramic substrate with better thermal conductivity and mechanical properties, and a preparation method and an application thereof.

In addition, the composite zirconia powder for toughening the aluminum nitride ceramic and the preparation method thereof are also provided.

In one aspect of the invention, the composite zirconia powder comprises an inner core and a shell layer wrapping the inner core, wherein the inner core is nano zirconia, and the shell layer is a mixture of alumina and aluminum nitride.

In some embodiments, the mass ratio of the core to the shell is 1: (0.44-2.87).

In some embodiments, the particle size of the composite zirconia powder is 60nm to 130 nm.

In some of these embodiments, the inner core has a radial dimension of 50nm to 100nm and the shell has a thickness of 10nm to 30 nm.

In another aspect of the present invention, a method for preparing the above composite zirconia powder is also provided, which comprises the following steps:

uniformly mixing nano zirconia powder, an alumina precursor, active carbon, a dispersing agent and water to obtain a suspension;

adding a pH regulator into the suspension, regulating the pH of the suspension to 7-8, standing, filtering and drying to obtain first mixed powder;

calcining the first mixed powder at 1200-1600 ℃ in a nitrogen atmosphere to obtain second mixed powder;

and calcining the second mixed powder at 600-700 ℃ in an air atmosphere to obtain the composite zirconia powder.

In some of these embodiments, the alumina precursor is selected from anhydrous AlCl₃、Al(NO₃)₃And Al₂(SO₄)₃One kind of (1).

In some embodiments, the mass ratio of the nano zirconia powder, the alumina precursor, the activated carbon, the dispersant and the water is 1: (3.26-13.9): (0.44-2.39): (0.1-0.36): (4.7-13.9).

In some embodiments, the first mixed powder is calcined at 1200-1600 ℃ for 2-10 hours;

in some embodiments, the second mixed powder is calcined at 600-700 ℃ for 1-5 hours.

On the other hand, the invention also provides an aluminum nitride ceramic substrate, which comprises the following preparation raw materials in parts by mass:

70-95 parts of aluminum nitride powder;

3-25 parts of a toughening agent; and

1-10 parts of sintering aid;

wherein the toughening agent is the composite zirconia powder.

In some of these embodiments, the sintering aid is selected from at least one of rare earth metal oxides, alkaline earth metal oxides, and metal fluorides.

In some embodiments, the aluminum nitride powder is 80 to 92 parts by mass, the toughening agent is 5 to 15 parts by mass, and the sintering aid is 3 to 5 parts by mass.

In another aspect of the present invention, a method for preparing an aluminum nitride ceramic substrate is also provided, which comprises the following steps:

mixing the preparation raw materials of the aluminum nitride ceramic substrate to prepare casting slurry;

preparing a casting green body by casting;

and removing the glue and sintering to obtain the aluminum nitride ceramic substrate.

In another aspect of the invention, the aluminum nitride ceramic substrate is used as a semiconductor packaging substrate.

In another aspect of the present invention, an electronic device is further provided, and a chip of the electronic device includes the aluminum nitride ceramic substrate.

The composite zirconia powder is of a core-shell structure and comprises a core and a shell layer wrapping the core, wherein the core is nano zirconia, and the shell layer is a mixture of alumina and aluminum nitride. The zirconia has the characteristics of high fracture toughness, strength, hardness, wear resistance and the like, shows excellent mechanical properties and can play a toughening effect in ceramics; but the thermal conductivity is lower and easy to agglomerate, and the problems of lower thermal conductivity and poorer uniformity of the ceramic exist in practical application. And the technical personnel find that when zirconium oxide powder is directly used as a toughening agent and added into aluminum nitride ceramic, zirconium oxide and aluminum nitride react to generate ZrN and zirconium oxynitride, so that the content of zirconium oxide is reduced, the expected toughening effect cannot be achieved, and the generated ZrN and zirconium oxynitride are easy to oxidize to generate volume expansion, so that the material is cracked. The composite zirconia powder is prepared by coating a shell layer formed by a specific material on the surface of the nano zirconia, is used as a toughening agent of an aluminum nitride ceramic substrate, can avoid the technical problems and ensure the toughening effect of the zirconia, and simultaneously is not easy to agglomerate due to the core-shell structure of the composite zirconia powder, so that the uniformity of the performance of the ceramic product can be ensured. The aluminum nitride ceramic substrate obtained by using the composite zirconia powder as the toughening agent has better mechanical property under the condition of ensuring that the thermal conductivity meets the use requirement of the semiconductor substrate.

Drawings

FIG. 1 is a schematic flow chart of a method for preparing a composite zirconia powder according to an embodiment of the present invention;

fig. 2 is a flow chart illustrating a method for manufacturing an aluminum nitride ceramic substrate according to an embodiment of the present invention.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The zirconia has the characteristics of high fracture toughness, strength, hardness, wear resistance and the like, shows excellent mechanical properties and can play a toughening effect in ceramics. The tetragonal zirconia is affected by external forces (temperature and stress), and when the tetragonal zirconia is transformed from a tetragonal structure to a monoclinic structure, a phase transformation effect is generated, the energy of damage is absorbed, and the change and extension of cracks are inhibited, and the change is called martensite transformation. When ZrO₂Cooling from high temperature to room temperature to undergo c → t → m isomerous transformation, wherein the phase transformation process of t → m generates 3-5% volume expansion, and m-ZrO heating to 1170 DEG C₂Conversion to t-ZrO₂The transformation process then undergoes volume shrinkage, and the phase change between the t-phase and m-phase is called ZrO₂Martensitic transformation, the volume change occurring during martensitic transformation causing ZrO₂The toughening effect of (2) is achieved.

However, the thermal conductivity of the zirconia material is low and is only 2-5W/m.K, when the zirconia material is used for toughening aluminum nitride ceramics, the thermal conductivity of the ceramics is reduced, and the problem of poor uniformity of the ceramics caused by zirconia particle agglomeration is easy to occur, so that the mechanical property of the aluminum nitride ceramics is influenced.

One embodiment of the invention provides composite zirconia powder, which is in a core-shell structure, wherein the core of the composite zirconia powder is nano zirconia, and the shell of the composite zirconia powder is a mixture of alumina and aluminum nitride.

The composite zirconia powder is of a core-shell structure, the core structure is nano zirconia, and the shell structure is a mixture of alumina and aluminum nitride. The aluminum oxide/aluminum nitride shell layer is coated on the surface of the nano zirconia, so that the phenomenon that the content of the zirconia is reduced due to impurities generated by zirconia reaction is avoided, the expected toughening effect cannot be achieved, and meanwhile, the zirconia is not easy to agglomerate due to the fact that the aluminum oxide/aluminum nitride shell layer is coated on the surface of the zirconia, and the uniformity of the performance of the ceramic product can be guaranteed. The aluminum nitride ceramic substrate obtained by using the composite zirconia powder as the toughening agent has excellent mechanical properties under the condition of ensuring that the thermal conductivity meets the use requirement of a semiconductor substrate.

In some embodiments, the mass ratio of core to shell is 1: (0.4-2.7).

In some embodiments, the composite zirconia powder has a particle size of 60nm to 130 nm.

In some of these embodiments, the core has a radial dimension of 50nm to 100nm and the shell has a thickness of 10nm to 30 nm.

Referring to fig. 1, another embodiment of the present invention further provides a method for preparing the composite zirconia powder, including the following steps S110 to S140.

Step S110: uniformly mixing nano zirconia powder, an alumina precursor, active carbon, a dispersing agent and water to obtain a suspension.

Step S120: and adding a pH regulator into the suspension to regulate the pH of the suspension to 7-8, standing, filtering and drying to obtain first mixed powder.

Step S130: and calcining the first mixed powder at 1200-1600 ℃ in a nitrogen atmosphere to obtain second mixed powder.

Step S140: and calcining the second mixed powder at 600-700 ℃ in an air atmosphere to obtain the composite zirconia powder.

Firstly, mixing nano zirconia powder with an alumina precursor, reacting the alumina precursor to generate AlOOH under the condition of specific pH, and depositing the AlOOH on the surface of the zirconia powder; then calcining the first mixed powder in a nitrogen atmosphere to enable AlOOH to be subjected to in-situ nitridation to generate AlN coated on the surface of the zirconia; and calcining the second mixed powder in an air atmosphere to remove carbon to obtain the composite zirconia powder. The preparation method of the composite zirconia powder has simple process and lower cost, and the prepared composite zirconia powder has good toughening effect when being used as an aluminum nitride ceramic toughening agent.

In some of these embodiments, the dispersant is selected from at least one of a phosphate ester, an acrylate salt, and fish oil.

In some embodiments, the mass ratio of the nano zirconia powder, the alumina precursor, the activated carbon, the dispersant and the water is 1: (3-15): (0.2-3): (0.01-0.5): (2-15). Further, the mass ratio of the nano zirconia powder, the alumina precursor, the activated carbon, the dispersing agent and the water is 1: (3.26-13.9): (0.44-2.39): (0.1-0.36): (4.7-13.9).

In some of these embodiments, the alumina precursor is selected from anhydrous AlCl₃、Al(NO₃)₃And Al₂(SO₄)₃One kind of (1).

In some of these embodiments, the pH adjusting agent is ammonia or sodium bicarbonate.

In some of these embodiments, the time of standing in step S120 is 2 hours to 5 hours. Through standing, AlOOH generated by the reaction can be uniformly deposited on the surface of the zirconia powder.

In some embodiments, the calcination time of the first mixed powder at 1200-1600 ℃ in step S130 is 2-10 hours;

in some embodiments, the calcination time of the second mixed powder at 600-700 ℃ in step S140 is 1-5 hours.

In some of these embodiments, the composite zirconia powder calcined in step S140 has a carbon content of < 1%.

The invention also provides an aluminum nitride ceramic substrate, which comprises the following preparation raw materials in parts by mass:

70-95 parts of aluminum nitride powder;

3-25 parts of a toughening agent; and

1-10 parts of sintering aid;

wherein the toughening agent is the composite zirconia powder.

The preparation raw materials of the aluminum nitride ceramic substrate comprise a toughening agent, aluminum nitride powder and a sintering aid with specific contents. The composite zirconia powder is used as a toughening agent and is matched with other preparation raw materials, so that the bending strength and the fracture toughness of the aluminum nitride ceramic substrate can be effectively improved under the condition of ensuring the high thermal conductivity of the aluminum nitride ceramic substrate, and the aluminum nitride ceramic substrate has excellent mechanical properties and is particularly suitable for serving as a semiconductor packaging substrate. Meanwhile, the doped zirconia is not easy to agglomerate in the aluminum nitride ceramic substrate, so that the uniformity of the aluminum nitride ceramic substrate is good.

In some of these embodiments, the sintering aid is selected from at least one of rare earth metal oxides, alkaline earth metal oxides, and metal fluorides.

Specifically, the sintering aid may be at least one selected from the group consisting of yttrium oxide, yttrium fluoride, calcium oxide, calcium carbide, calcium fluoride, and boron oxide. The sintering aid is helpful for improving the compactness of the aluminum nitride ceramic substrate.

In some embodiments, the aluminum nitride powder is 80 to 92 parts by mass, the toughening agent is 5 to 15 parts by mass, and the sintering aid is 3 to 5 parts by mass. The aluminum nitride ceramic substrate has high thermal conductivity and good bending strength and fracture toughness.

In some embodiments, the raw materials for preparing the aluminum nitride ceramic substrate further include a binder, a plasticizer, a dispersant, a defoaming agent, and other chemical additives.

In some of the examples, the aluminum nitride ceramic substrate has a thermal conductivity of 120W/mK to 175W/mK, a flexural strength of 480MPa to 580MPa, and a fracture toughness of 4.0MPa m^1/2～5.0MPa·m^1/2. Further, the aluminum nitride ceramic substrate has a thermal conductivity of 141W/mK to 172W/mK, a bending strength of 521.1MPa to 567.3MPa, and a fracture toughness of 4.03MPa m^1/2～4.82MPa·m^1/2。

Referring to fig. 2, another embodiment of the present invention further provides a method for preparing the aluminum nitride ceramic substrate, including the following steps S210 to S230.

Step S210: and (3) ball-milling and mixing the toughening agent, the aluminum nitride powder and the sintering aid to prepare the casting slurry.

Step S220: and (4) preparing a casting green body by casting.

Step S230: and removing the glue and sintering to obtain the aluminum nitride ceramic substrate.

The preparation method of the aluminum nitride ceramic substrate has the advantages of simple process and low cost, and the prepared aluminum nitride ceramic substrate has good heat-conducting property and mechanical property.

In some of these embodiments, the temperature of the binder removal is 450 ℃ to 600 ℃.

In some of these embodiments, the sintering temperature is 1700 ℃ to 1900 ℃ and the sintering time is 1 hour to 10 hours.

The invention also provides an application of the aluminum nitride ceramic substrate as a semiconductor packaging substrate.

The invention further provides electronic equipment, and a chip of the electronic equipment comprises the aluminum nitride ceramic substrate.

The aluminum nitride ceramic substrate is adopted as the semiconductor packaging substrate in the chip of the electronic equipment, and the aluminum nitride ceramic substrate has good thermal conductivity and mechanical property, so that the aluminum nitride ceramic substrate is stable under the use conditions of high current, high temperature and the like, is not easy to damage, and has long service life.

In some of these embodiments, the electronic devices include, but are not limited to, computers, smart phones.

The composite zirconia powder, the aluminum nitride ceramic substrate and the method for producing the same according to the present invention will be further described below with reference to specific examples.

Example 1:

the preparation method of the composite zirconia powder of the embodiment is as follows:

weighing 100g of nano zirconia powder and 520g of AlCl₃50.5g of activated carbon powder and 6.7g of fish oil are respectively added into 800g of water to be fully stirred and uniformly dispersed, and then ammonia water is slowly dripped until the pH value of the aqueous solution reaches 7; the solution was allowed to stand for 5 hours, and after the reaction was completed, the resulting precipitate was filtered and dried. Will be dried wellThe mixed powder is put into a sintering furnace, and the temperature is raised to 1350 ℃ under the condition of nitrogen atmosphere and is kept for 2 hours. And (3) putting the calcined mixed powder into an air atmosphere sintering furnace, heating to 650 ℃ to remove carbon, so that the carbon content in the powder is less than 1%, and obtaining the composite zirconia powder. The mass ratio of the core to the shell of the prepared composite zirconia powder is 1:0.82, the particle size of the core is 65nm, and the thickness of the shell is 15 nm.

The preparation method of the aluminum nitride ceramic substrate of the embodiment is as follows:

weighing 7.8 parts of the composite zirconia powder, 89 parts of the aluminum nitride powder and Y according to the mass parts₂O₃3.5 parts of aluminum nitride ceramic substrate, preparing a ceramic substrate green body by a tape casting process after ball milling and mixing, discharging glue at the temperature of 450 ℃, and then sintering for 2 hours at the temperature of 1800 ℃ to obtain the aluminum nitride ceramic substrate of the embodiment.

Example 2:

the preparation method of the composite zirconia powder of the embodiment is as follows:

100g of nano zirconia powder and 1100g of Al were weighed₂(SO₄)₃133g of activated carbon powder and 14g of fish oil are respectively added into 1400g of water, fully stirred and uniformly dispersed, and then ammonia water is slowly added dropwise until the pH value of the aqueous solution reaches 7.5; the solution was allowed to stand for 3.5 hours, and after the reaction was completed, the resulting precipitate was filtered and dried. And (3) putting the dried mixed powder into a sintering furnace, heating to 1400 ℃ under the condition of nitrogen atmosphere, and preserving heat for 2 hours. And (3) putting the calcined mixed powder into an air atmosphere sintering furnace, heating to 650 ℃ to remove carbon, so that the carbon content in the powder is less than 1%, and obtaining the composite zirconia powder. The mass ratio of the core to the shell of the prepared composite zirconia powder is 1:1.33, the particle size of the core is 82nm, and the thickness of the shell is 22 nm.

The preparation method of the aluminum nitride ceramic substrate of the embodiment is as follows:

weighing 12 parts of the composite zirconia powder, 83 parts of aluminum nitride powder and CaF according to the mass parts₂5 parts, preparing a ceramic substrate green body by a tape casting process after ball milling and mixing, discharging glue at the temperature of 650 ℃, and then sintering for 2 hours at the temperature of 1800 ℃ to obtain the aluminum nitride ceramic substrate of the embodiment.

Example 3:

the preparation method of the composite zirconia powder of the embodiment is as follows:

100g of nano zirconia powder and 850g of Al were weighed₂(NO₃)₃83g of activated carbon powder and 10.33g of fish oil are respectively added into 1050g of water, fully stirred and uniformly dispersed, and then ammonia water is slowly dripped until the pH value of the aqueous solution reaches 8; the solution was allowed to stand for 3.5 hours, and after the reaction was completed, the resulting precipitate was filtered and dried. And (3) putting the dried mixed powder into a sintering furnace, heating to 1400 ℃ under the condition of nitrogen atmosphere, and preserving heat for 2 hours. And (3) putting the calcined mixed powder into an air atmosphere sintering furnace, heating to 650 ℃ to remove carbon, so that the carbon content in the powder is less than 1%, and obtaining the composite zirconia powder. The mass ratio of the core to the shell of the prepared composite zirconia powder is 1:0.97, the particle size of the core is 79nm, and the thickness of the shell is 28 nm.

The preparation method of the aluminum nitride ceramic substrate of the embodiment is as follows:

weighing 25 parts of the composite zirconia powder, 70 parts of aluminum nitride powder and Y according to the mass parts₂O₃5 parts, preparing a ceramic substrate green body by a tape casting process after ball milling and mixing, discharging glue at the temperature of 850 ℃, and then sintering for 2 hours at the temperature of 1800 ℃ to obtain the aluminum nitride ceramic substrate of the embodiment.

Example 4:

the composite zirconia powder used in this example was the same as in example 1.

The preparation method of the aluminum nitride ceramic substrate of the embodiment is as follows:

weighing 3 parts of the composite zirconia powder, 95 parts of aluminum nitride powder and Y according to the mass parts₂O₃2 parts, preparing a ceramic substrate green body by a tape casting process after ball milling and mixing, discharging glue at the temperature of 450 ℃, and then sintering for 2 hours at the temperature of 1800 ℃ to obtain the aluminum nitride ceramic substrate of the embodiment.

Example 5:

the composite zirconia powder used in this example was the same as in example 2.

The preparation method of the aluminum nitride ceramic substrate of the embodiment is as follows:

weighing 15 parts of the composite zirconia powder, 80 parts of aluminum nitride powder and CaF according to the mass parts₂5 parts, preparing a ceramic substrate green body by a tape casting process after ball milling and mixing, discharging glue at the temperature of 650 ℃, and then sintering for 2 hours at the temperature of 1800 ℃ to obtain the aluminum nitride ceramic substrate of the embodiment.

Example 6:

the composite zirconia powder used in this example was the same as in example 3.

The preparation method of the aluminum nitride ceramic substrate of the embodiment is as follows:

weighing 5 parts of the composite zirconia powder, 92 parts of aluminum nitride powder and Y according to the mass parts₂O₃3 parts of the aluminum nitride ceramic substrate, preparing a ceramic substrate green body by a tape casting process after ball milling and mixing, discharging glue at the temperature of 850 ℃, and then sintering for 2 hours at the temperature of 1800 ℃ to obtain the aluminum nitride ceramic substrate of the embodiment.

Comparative example 1:

the aluminum nitride ceramic substrate of comparative example 1 was prepared in substantially the same manner as in example 1, except that the composite zirconia powder was not added to the aluminum nitride ceramic substrate of comparative example 1.

Comparative example 2:

the method for producing the aluminum nitride ceramic substrate of the present comparative example was as follows:

weighing 7.8 parts of nano zirconia powder, 89 parts of aluminum nitride powder and Y according to the mass parts₂O₃3.5 parts of aluminum nitride ceramic substrate, preparing a ceramic substrate green body by a tape casting process after ball milling and mixing, discharging glue at the temperature of 450 ℃, and then sintering for 2 hours at the temperature of 1800 ℃ to obtain the aluminum nitride ceramic substrate of the embodiment.

The test results of the thermal conductivity and mechanical properties of the aluminum nitride ceramic substrates prepared in examples 1 to 6 and comparative examples 1 to 2 are shown in table 1.

TABLE 1 test results of thermal conductivity and mechanical properties of the aluminum nitride ceramic substrates prepared in examples 1 to 6 and comparative examples 1 to 2

	Thermal conductivity (W/m. K)	Bending strength (MPa)	Fracture toughness (MPa. m)1/2)
				Example 1	168	521.1	4.03
Example 2	155	547.6	4.35
				Example 3	132	563.4	4.72
Example 4	172	528.7	4.11
				Example 5	163	551.2	4.41
Example 6	141	567.3	4.82
				Comparative example 1	170	450	3.05
Comparative example 2	98	492	3.74

As can be seen from the data in Table 1, the thermal conductivity of the aluminum nitride ceramic substrates prepared in examples 1 to 6 was 141W/mK to 172W/mK, the flexural strength was 521.1MPa to 567.3MPa, and the fracture toughness was 4.03MPa m^1/2～4.82MPa·m^1/2Has good heat-conducting property and mechanical property. Compared with the common aluminum nitride ceramic substrate prepared in the comparative example 1, the aluminum nitride ceramic substrate prepared in the examples 1 to 6 has improved bending strength and fracture toughness and better mechanical properties under the condition that the aluminum nitride ceramic substrate meets the requirement of the thermal conductivity of the semiconductor packaging substrate by firstly preparing the aluminum oxide/aluminum nitride-coated zirconium oxide powder as a toughening agent, and mixing the aluminum oxide/aluminum nitride-coated zirconium oxide powder with the aluminum nitride powder and the sintering aid in a certain proportion. Compared with the aluminum nitride ceramic substrate of the comparative example 2, the aluminum nitride ceramic substrates prepared in the examples 1 to 6 have higher thermal conductivity, and the bending strength and the fracture toughness are both obviously improved, which shows that the composite zirconia powder with a unique structure is used as a toughening agent, so that the bending strength and the fracture toughness of the aluminum nitride ceramic substrate can be greatly improved under the condition of ensuring the thermal conductivity of the aluminum nitride ceramic substrate, and the toughening effect is better compared with the toughening effect of the aluminum nitride ceramic substrate prepared by directly adding zirconia or alumina.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, so as to understand the technical solutions of the present invention specifically and in detail, but not to be understood as the limitation of the protection scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. It should be understood that the technical solutions provided by the present invention, which are obtained by logical analysis, reasoning or limited experiments, are within the scope of the present invention as set forth in the appended claims. Therefore, the protection scope of the present invention should be subject to the content of the appended claims, and the description and the drawings can be used for explaining the content of the claims.