CN112573903A

CN112573903A - Aluminum oxide composite substrate material and preparation method thereof

Info

Publication number: CN112573903A
Application number: CN201910943857.XA
Authority: CN
Inventors: 邓桂勇; 申会平; 罗大虎
Original assignee: State Grid Henan Electric Power Co Tongbai County Power Supply Co
Current assignee: State Grid Henan Electric Power Co Tongbai County Power Supply Co
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2021-03-30
Anticipated expiration: 2039-09-30
Also published as: CN112573903B

Abstract

The invention discloses an alumina composite substrate material and a preparation method thereof, belonging to the technical field of circuit substrate materials and being prepared from the following raw materials in parts by weight: 25-33 parts of aluminum oxide, 10-15 parts of polyacrylamide, 15-20 parts of epoxy resin, 3-5 parts of filler, 12-18 parts of attapulgite, 2-5 parts of sintering aid, 0.6-1.2 parts of ammonium persulfate, 0.5-1 part of tributyl phosphate and 135 parts of water. The alumina composite substrate material of the invention shows good comprehensive performance: the material has excellent mechanical performance, bending strength of over 443MPa, elastic modulus of over 355GPa, heat conduction coefficient of over 95.2W/(m × K), excellent heat conducting performance and good heat dissipating effect. The invention has good formula and process adaptability, not only improves the toughness of the substrate material, but also has excellent heat-conducting property, and has important progress significance for the development of the alumina substrate material.

Description

Aluminum oxide composite substrate material and preparation method thereof

Technical Field

The invention relates to the technical field of circuit substrate materials, in particular to an aluminum oxide composite substrate material and a preparation method thereof.

Background

Alumina ceramic substrates are the most commonly used substrate materials in the electronics industry because of their high mechanical, thermal, and electrical properties, strength and chemical stability relative to most other oxide ceramics, and because of their abundant raw material sources, they are suitable for various technical manufacturing. The alumina ceramic has better conductivity, mechanical strength and high temperature resistance, and has more and more extensive application in modern society because of the superior performance, thereby meeting the requirements of daily use and special performance. With the continuous development of modern communication technology, electronic components are continuously changed to be simplified, miniaturized and high in integration level, the requirements on a circuit packaging process are also improved, and the requirements on an aluminum oxide ceramic packaging substrate are increased more and more. The alumina ceramic has good performances in the aspects of strength, heat resistance, impact resistance, electric insulation, corrosion resistance and the like, and has sufficient raw materials, low price, complete manufacturing and processing system and important function in industrial packaging. In the prior art, a high-temperature sintering method is usually adopted for preparing the alumina substrate, some alumina substrates can even reach over 1800 ℃, so that the cost is high, and the traditional alumina substrate is fragile and cannot be produced and used in large size.

The patent document with the publication number of CN102030515A discloses an alumina-based ceramic heat dissipation substrate material synthesized at low temperature and a preparation method thereof, wherein alumina, yttrium oxide or lanthanum oxide is used as a raw material, silicon dioxide and lithium carbonate are used as sintering aids, and the alumina-based ceramic with lower sintering temperature and high heat dissipation performance is prepared by a traditional solid phase reaction method; in addition, the sintering temperature of the material can be reduced by doping a small amount of sintering aid, and the problem of high sintering temperature of pure alumina ceramic is solved; the alumina-based functional ceramic prepared by the formula has the advantages of good heat dissipation, high temperature resistance, moisture resistance and good heat conductivity.

Patent document No. CN103360039A discloses a large-size chip ceramic substrate and a method for manufacturing the same. The ceramic substrate is 150-350 mm in side length and 0.2-10 mm in thickness, and comprises the following ingredients in percentage by mass: 95% -99.8% of alumina powder and 0.2% -5% of composite sintering aid; and additionally adding an organic functional additive accounting for 4-7% of the total mass of the alumina powder and the composite sintering additive, and a solvent accounting for 10-18% of the total mass of the alumina powder and the composite sintering additive. The method reforms the injection molding mode in the gel injection molding process, changes the mode of injecting slurry into a mold by using the self weight of slurry as a power source in the prior art, and prepares the large-size sheet alumina ceramic substrate material by adopting a controllable injection molding and composite gel excitation mode of a stable pressure source from bottom to top.

The sintering temperature of the two methods still reaches about 1500 ℃, the thermal conductivity is not high, and the problem that the alumina-based ceramic substrate is brittle cannot be solved.

Disclosure of Invention

In view of the above, the invention provides an alumina composite substrate material and a preparation method thereof, which have good formula and process adaptability, not only improve the toughness of the substrate material, but also have excellent heat conductivity.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

an aluminum oxide composite substrate material is prepared from the following raw materials in parts by weight: 25-33 parts of aluminum oxide, 10-15 parts of polyacrylamide, 15-20 parts of epoxy resin, 3-5 parts of filler, 12-18 parts of attapulgite, 2-5 parts of sintering aid, 0.6-1.2 parts of ammonium persulfate, 0.5-1 part of tributyl phosphate and 135 parts of water.

Further, the alumina composite substrate material is prepared from the following raw materials in parts by weight: 26-32 parts of alumina, 11-14 parts of polyacrylamide, 16-19 parts of epoxy resin, 3.5-4.5 parts of filler, 13-17 parts of attapulgite, 2.5-4 parts of sintering aid, 0.7-1.1 parts of ammonium persulfate, 0.6-0.9 part of tributyl phosphate and 130 parts of water.

Further, the filler is one or more of silicon dioxide, boron oxide, calcium oxide and fly ash.

Further, the filler is a mixture of silica, boron oxide, calcium oxide and fly ash, and the weight ratio of silica to the weight ratio of the calcium oxide to the weight ratio of the fly ash to the weight ratio of the boron oxide to the weight ratio of the calcium oxide to the weight ratio of the fly ash to: boron oxide: calcium oxide: the fly ash is 1:0.5-0.8: 0.3-0.5: 0.08-0.12.

Further, the filler is a mixture of silica, boron oxide, calcium oxide and fly ash, and the weight ratio of silica to the weight ratio of the calcium oxide to the weight ratio of the fly ash to the weight ratio of the boron oxide to the weight ratio of the calcium oxide to the weight ratio of the fly ash to: boron oxide: calcium oxide: the fly ash is 1:0.6: 0.4: 0.1.

further, the sintering aid is one or two of ytterbium oxide and cerium dioxide.

Further, the sintering aid is ytterbium oxide and cerium dioxide, and the weight ratio of ytterbium oxide: the ratio of cerium dioxide is 1: 2-3.

Further, the preparation method of the alumina composite substrate material comprises the following steps:

s1: adding alumina, a filler, attapulgite, a sintering aid, tributyl phosphate and water into a ball mill, and ball-milling for 8-10h at normal temperature at the rotating speed of 200-300r/min to obtain a ball grinding material;

s2: placing polyacrylamide, epoxy resin and ammonium persulfate in a stirrer, stirring at the rotating speed of 300-400r/min at normal temperature for 20-30min, then adding the ball milling material obtained in the step S1, keeping the rotating speed unchanged, and continuously stirring for 45-60min to obtain a mixture;

s3: placing the mixture obtained in the step S2 into a press for pressing and forming after spray granulation to obtain a blank body;

s4: placing the blank obtained in the step S3 in a sintering furnace, introducing argon, preheating at 450 ℃, heating for 10-20min, preserving heat for 1-2h, then sintering at 1000 ℃ with low temperature of 900-;

s5: and (4) placing the sintering material obtained in the step S4 in a vacuum furnace for heat treatment at 900-1000 ℃ for 3-4h, wherein the vacuum degree is between-0.05 Mpa and-0.08 Mpa, cooling to room temperature, and then cleaning.

As early as 1982, a ceramic substrate has been developed by the us universal electrics, for over half a century to date, and has not been widespread for as long as this time, for which too many reasons have been involved. The domestic ceramic substrate technology is blocked abroad before, the domestic ceramic substrate is basically used by import, the international ceramic substrate market is mainly occupied by the companies such as Japan Jing porcelain, Seoul semiconductor, American Rogers and the like, and the domestic imported ceramic substrate is basically from Japan and Korea. The ceramic substrate in China is developed from 2000 years later, and in 2004, the ceramic substrate of China is formally developed by the research institute of eighty-four-two, representing that China formally breaks through the technical blockade of the ceramic substrate and has the ceramic substrate which is independently developed and produced in China. 2012 later, the related research and development of ceramic substrates of various scientific research units in China are quite mature, and the domestic ceramic substrates begin to formally open the market with the support of the country on the conversion of scientific and technological achievements. The reason why the application of the domestic ceramic substrate is not opened at a later date is not only for the market reason but also for the scientific research technology which is not mature enough.

Along with the rapid development of the fields of high-speed rails, spaceflight, war industry and the like in China, the demand on power electronic devices is getting larger and larger, the power electronic devices develop towards high temperature, high frequency, low power consumption, intellectualization, modularization and systematization, which provides a serious challenge for the heat dissipation of the whole electronic device, and the substrate in the power device is used for absorbing the heat generated by the chip and transmitting the heat to the heat sink to realize the heat exchange with the outside, so that the preparation of the high-heat-conductivity substrate material becomes the key point for researching and developing high-power module electronic products. Those skilled in the art have been keen on the study of thermal conductivity of alumina substrates. For example, patent publication No. CN103408291A discloses a high thermal conductivity alumina ceramic substrate, which is prepared by uniformly stirring ceramic powder, binder, plasticizer, dispersant and solvent, casting to obtain a ceramic green ceramic substrate, removing the binder, and sintering. The substrate uses a butanol, isopropanol and butyl acetate solvent system to replace the traditional toluene as a main solvent, and can greatly increase the dissolving effect of the solvent on PVB, thereby ensuring the uniformity of the raw porcelain slurry. For another example, patent document CN105405955A discloses a process for producing a ceramic heat dissipating substrate for LEDs. The process comprises the following steps: preparing a composite sintering aid; preparing ceramic slurry; and (5) forming the ceramic. The prepared ceramic substrate has the advantages of large heat conductivity coefficient, excellent heat resistance, high bending strength, no bending, warping and other phenomena, the densification of the alumina ceramic sintered body is realized, and the heat conductivity of the ceramic substrate is greatly improved. Those skilled in the art have made great breakthroughs in continuously improving the thermal conductivity of the material, but few researches on the brittleness defect inherent in the ceramic material. Those skilled in the art believe that brittleness and easy fracture are inherent defects of ceramic materials and are not easy to improve, and the study on the defects consumes a lot of manpower and material resources, and most importantly, even if the study on the improvement of the toughness of the material by combining other substances with alumina is carried out, the thermal conductivity of the composite substrate is reduced, and the advantages of the alumina substrate cannot be exerted. Once the heat dissipation performance of the substrate is poor, the heat of the chip cannot be dissipated timely, the performance of the chip is affected, or the service life of the chip is shortened, even the chip fails, so that the use and development of the substrate are strictly limited. Therefore, those skilled in the art are reluctant to expend energy and money to develop the toughness of the modified alumina substrate, which is one of the important factors limiting the development of the alumina substrate.

The invention has the beneficial effects that:

the invention is compounded by alumina, polyacrylamide, epoxy resin, filler, attapulgite, sintering aid, ammonium persulfate and tributyl phosphate. The alumina ceramic substrate has excellent electric insulation performance, high heat conduction characteristic, excellent soft weldability and high adhesion strength, can be etched into various patterns like a PCB (printed circuit board), and has great current carrying capacity. Therefore, the ceramic substrate has become a basic material for high-power electronic circuit structure technology and interconnection technology. The polyacrylamide, the epoxy resin and the ammonium persulfate are combined and compounded with the alumina, so that the heat conduction coefficient is higher. The attapulgite has better suspension property and weather resistance, insulation property, high temperature resistance, strong adhesive force and good dispersion property, can be uniformly distributed in an organic layer, and enhances the binding force between alumina and organic matters of fillers. And the ceramic substrate and the epoxy resin are cooperated to resist crack twinning, so that the brittleness of the ceramic substrate is reduced. Tributyl phosphate is used as a defoaming agent.

The filler is a mixture of silicon dioxide, boron oxide, calcium oxide and fly ash, so that the shrinkage rate of material molding and sintering is reduced, and the dimensional stability and the mechanical strength of the material are improved. The fly ash has the particle size range of 10-45 mu m, the porosity of 50-80 percent, the particles are in a porous honeycomb structure, the specific surface area is larger, the adsorption activity is higher, the high temperature resistance and the chemical corrosion resistance are realized, the durability and the strength of the material are improved, the particle separation phenomenon is reduced, the shrinkage and the cracking of the material are reduced, and the cracking resistance is enhanced. The sintering aid is ytterbium oxide and cerium dioxide, the oxygen-expelling capacity is strong, the stability is good, impurities in the substrate material are removed, a more compact structure is formed, the sintering temperature of the alumina ceramic is reduced, the heat-conducting property of the material is improved, and the heat-radiating effect is better.

In the sintering process, argon is introduced in the sintering process, so that the mixing of gas impurities in the air is reduced, crystal grains are purified, the purity is improved, and the product percent of pass is improved. Preheating is carried out firstly, so that the blank is heated uniformly, and deformation in the sintering process is prevented. And low-temperature sintering is used for discharging gas in the blank and preventing the blank from generating defects such as air holes, needle holes and the like. And (4) bonding the high-temperature sintered blank into a whole to obtain the alumina substrate material with higher strength. Finally, vacuum heat treatment is carried out, gas in the sintering material is discharged again, the purity of the material is improved, and the rejection rate is greatly reduced.

The alumina composite substrate material of the invention has good comprehensive performance: the high-strength heat-conducting material has excellent mechanical properties, bending strength of over 443MPa, elastic modulus of over 355GPa, heat conduction coefficient of over 95.2W/(m × K), excellent heat conduction performance and good heat dissipation effect, and the qualified rate reaches over 98 percent by adopting the process. The invention has good formula and process adaptability, not only improves the toughness of the substrate material, but also has excellent heat-conducting property, and has important progress significance for the development of the alumina substrate material.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention are clearly and completely described below. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.

TABLE 1 examples 1-6 parts by weight of each raw material (parts)

Example 1

This example provides an alumina composite substrate material, which is prepared from the raw materials in the parts by weight shown in table 1. The filler is silica. The sintering aid is ytterbium oxide.

The preparation method of the aluminum oxide composite substrate material comprises the following steps:

s1: adding alumina, a filler, attapulgite, a sintering aid, tributyl phosphate and water into a ball mill, and ball-milling at the normal temperature for 10 hours at the rotating speed of 200r/min to obtain a ball grinding material;

s2: placing polyacrylamide, epoxy resin and ammonium persulfate in a stirrer, stirring at the rotating speed of 300r/min at normal temperature for 30min, then adding the ball-milled material obtained in the step S1, keeping the rotating speed unchanged, and continuously stirring for 60min to obtain a mixture;

s4: placing the green body obtained in the step S3 in a sintering furnace, introducing argon gas with the flow rate of 80L/min, preheating at 350 ℃, heating for 10min, preserving heat for 2h, then sequentially sintering at low temperature of 900 ℃, heating for 20min, preserving heat for 3h, sintering at high temperature of 1300 ℃, heating for 45min, preserving heat for 4h, and finally cooling to room temperature to obtain a sintered material;

s5: and (4) placing the sintered material obtained in the step (S4) in a vacuum furnace for heat treatment at 900 ℃ for 4 hours, wherein the vacuum degree is-0.05 Mpa, cooling to room temperature, and then cleaning.

Example 2

This example provides an alumina composite substrate material, which is prepared from the raw materials in the parts by weight shown in table 1. The filler is boron oxide. The sintering aid is cerium dioxide.

s1: adding alumina, a filler, attapulgite, a sintering aid, tributyl phosphate and water into a ball mill, and ball-milling for 8-10h at the normal temperature at the rotating speed of 250r/min to obtain a ball grinding material;

s2: placing polyacrylamide, epoxy resin and ammonium persulfate in a stirrer, stirring at the rotating speed of 350r/min at normal temperature for 25min, then adding the ball-milled material obtained in the step S1, keeping the rotating speed unchanged, and continuously stirring for 50min to obtain a mixture;

s4: placing the green body obtained in the step S3 in a sintering furnace, introducing argon gas with the flow rate of 80L/min, preheating at 400 ℃, heating for 15min, preserving heat for 1.5h, then sintering at 950 ℃ in sequence, heating for 25min, preserving heat for 2.5h, sintering at 1350 ℃ in sequence, heating for 50min, preserving heat for 3.5h, and finally cooling to room temperature to obtain a sintered material;

s5: and (4) placing the sintered material obtained in the step (S4) in a vacuum furnace for heat treatment at 950 ℃ for 3.5h, wherein the vacuum degree is-0.06 Mpa, cooling to room temperature, and then cleaning.

Example 3

This example provides an alumina composite substrate material, which is prepared from the raw materials in the parts by weight shown in table 1. The filler is fly ash. The sintering aid is ytterbium oxide and cerium dioxide, and the weight ratio of ytterbium oxide: the ratio of cerium oxide is 1:2.

s1: adding alumina, a filler, attapulgite, a sintering aid, tributyl phosphate and water into a ball mill, and ball-milling for 8 hours at normal temperature at the rotating speed of 300r/min to obtain a ball grinding material;

s2: placing polyacrylamide, epoxy resin and ammonium persulfate in a stirrer, stirring at the rotation speed of 400r/min for 20min at normal temperature, then adding the ball-milled material obtained in the step S1, keeping the rotation speed unchanged, and continuously stirring for 45min to obtain a mixture;

s4: placing the green body obtained in the step S3 in a sintering furnace, introducing argon gas with the flow rate of 80L/min, preheating at 450 ℃, heating for 20min, preserving heat for 1h, then sequentially sintering at the low temperature of 1000 ℃, heating for 30min, preserving heat for 2h, sintering at the high temperature of 1400 ℃, heating for 60min, preserving heat for 3h, and finally cooling to room temperature to obtain a sintered material;

s5: and (4) placing the sintering material obtained in the step S4 into a vacuum furnace for heat treatment at 1000 ℃ for 3 hours, wherein the vacuum degree is-0.08 Mpa, cooling to room temperature, and then cleaning.

Example 4

This example provides an alumina composite substrate material, which is prepared from the raw materials in the parts by weight shown in table 1. The filler is a mixture of silicon dioxide, boron oxide, calcium oxide and fly ash, and the weight ratio of the silicon dioxide to the fly ash is as follows: boron oxide: calcium oxide: the fly ash is 1:0.6: 0.4: 0.1. the sintering aid is ytterbium oxide and cerium dioxide, and the weight ratio of ytterbium oxide: the ratio of cerium oxide is 1: 2.5. The preparation method of the alumina composite substrate material is the same as that of the embodiment 1.

Example 5

This example provides an alumina composite substrate material, which is prepared from the raw materials in the parts by weight shown in table 1. The filler is a mixture of silicon dioxide, boron oxide, calcium oxide and fly ash, and the weight ratio of the silicon dioxide to the fly ash is as follows: boron oxide: calcium oxide: the fly ash is 1:0.5: 0.3: 0.08. the sintering aid is ytterbium oxide and cerium dioxide, and the weight ratio of ytterbium oxide: the ratio of cerium oxide is 1:2. The preparation method of the alumina composite substrate material is the same as that of the embodiment 2.

Example 6

This example provides an alumina composite substrate material, which is prepared from the raw materials in the parts by weight shown in table 1. The filler is a mixture of silicon dioxide, boron oxide, calcium oxide and fly ash, and the weight ratio of the silicon dioxide to the fly ash is as follows: boron oxide: calcium oxide: the fly ash is 1: 0.8: 0.5: 0.12. The sintering aid is ytterbium oxide and cerium dioxide, and the weight ratio of ytterbium oxide: the ratio of cerium oxide is 1: 3. The preparation method of the alumina composite substrate material is the same as that of the embodiment 3.

Example 7

This example provides an alumina composite substrate material, the raw materials and the preparation method are the same as example 5, but different from example 5, in this example, 0.6 parts by weight of zirconia is added, and in the preparation method, the zirconia is added together with the filler in step S1.

Example 8

This example provides an alumina composite substrate material, the raw materials and the preparation method are the same as example 5, but different from example 6, in this example, 0.7 parts by weight of zirconia is added, and in the preparation method, the zirconia is added together with the filler in step S1.

The particle size range of the fly ash is 10-45 mu m, and the porosity is 50% -80%. The grain diameter of the alumina is 2-4 μm. The mesh number of the filler and the sintering aid is 80-150 meshes, so that the qualification rate of the product is ensured, and the heat conductivity of the material is improved. The smaller the particle size of the alumina, the greater its corresponding total surface area, requiring more liquid phase wetting. The smaller the alumina particle size, the more difficult it is for the alumina particles to be fully wetted by the liquid phase, and the repulsive force toward the outside is generated between the alumina particles which are not wetted, which hinders the sintering densification. The larger the alumina particle size, the smaller its corresponding total surface area, and the less liquid phase wetting is required, the higher its sintered density should be. The particle size is larger, the sintering activity is reduced, and the powder with larger particle size has larger apparent density.

In examples 7 and 8, zirconia was added, which had high mechanical strength and toughness, good thermal shock resistance, and reduced brittleness of the substrate material by synergistic effect with the filler and the epoxy resin.

Comparative example 1

This comparative example provides an alumina composite substrate material, which does not contain a filler, unlike example 1.

Comparative example 2

This comparative example provides an alumina composite substrate material, which does not contain a sintering aid, unlike example 1.

Comparative example 3

This comparative example provides an alumina composite substrate material, which does not contain attapulgite unlike example 1.

Comparative example 4

This comparative example provides an alumina composite substrate material, and unlike example 1, the production method in this comparative example does not perform vacuum heat treatment in step S5.

Test method

The alumina composite substrate materials of examples 1 to 8 and comparative examples 1 to 4 were subjected to a performance test.

The heat transfer coefficient is performed according to GB/T10297-2015 standard. The bending strength is performed according to the GB/T6569-2006 standard. The elastic modulus test is carried out according to the GB/T10700-2006 standard.

Table 2 test results of alumina composite substrate materials of examples 1 to 8 and comparative examples 1 to 4

By combining table 2, the performance of the alumina composite substrates of examples 1-8 and comparative examples 1-4 of the present invention is tested, and it can be seen that the alumina composite substrate materials of examples 1-8 all exhibit good combination properties: the high-strength heat-conducting material has excellent mechanical properties, bending strength of over 443MPa, elastic modulus of over 355GPa, heat conduction coefficient of over 95.2W/(m × K), excellent heat conduction performance and good heat dissipation effect, and the qualified rate reaches over 98 percent by adopting the process. The comparative example 1 lacks the filler, the comparative example 2 lacks the sintering aid, the comparative example 3 lacks the attapulgite, the mechanical property and the heat-conducting property of the material are obviously reduced, and the change of the components of the material influences the performance of the product. Comparative example 4 has no vacuum heat treatment, the performance of the material is reduced, which shows that the process and the formula of the application have good adaptability and can effectively improve the product quality.

Finally, the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and other modifications or equivalent substitutions made by the technical solutions of the present invention by those of ordinary skill in the art should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. An alumina composite substrate material, characterized in that: the feed is prepared from the following raw materials in parts by weight: 25-33 parts of aluminum oxide, 10-15 parts of polyacrylamide, 15-20 parts of epoxy resin, 3-5 parts of filler, 12-18 parts of attapulgite, 2-5 parts of sintering aid, 0.6-1.2 parts of ammonium persulfate, 0.5-1 part of tributyl phosphate and 135 parts of water.

2. The alumina composite substrate material of claim 1, wherein: the feed is prepared from the following raw materials in parts by weight: 26-32 parts of alumina, 11-14 parts of polyacrylamide, 16-19 parts of epoxy resin, 3.5-4.5 parts of filler, 13-17 parts of attapulgite, 2.5-4 parts of sintering aid, 0.7-1.1 parts of ammonium persulfate, 0.6-0.9 part of tributyl phosphate and 130 parts of water.

3. The alumina composite substrate material of claim 2, wherein: the filler is one or more of silicon dioxide, boron oxide, calcium oxide and fly ash.

4. The alumina composite substrate material of claim 3, wherein: the filler is a mixture of silicon dioxide, boron oxide, calcium oxide and fly ash, and the weight ratio of the silicon dioxide to the fly ash is as follows: boron oxide: calcium oxide: the fly ash is 1:0.5-0.8: 0.3-0.5: 0.08-0.12.

5. The alumina composite substrate material of claim 4, wherein: the filler is a mixture of silicon dioxide, boron oxide, calcium oxide and fly ash, and the weight ratio of the silicon dioxide to the fly ash is as follows: boron oxide: calcium oxide: the fly ash is 1:0.6: 0.4: 0.1.

6. the alumina composite substrate material of claim 5, wherein: the sintering aid is one or two of ytterbium oxide and cerium dioxide.

7. The alumina composite substrate material of claim 6, wherein: the sintering aid is ytterbium oxide and cerium dioxide, and the weight ratio of ytterbium oxide: the ratio of cerium dioxide is 1: 2-3.

8. The method of preparing an alumina composite substrate material as claimed in any one of claims 1 to 7, wherein: comprises the following steps: