阅读说明：本技术 一种氮化硅基板烧结方法 (Sintering method of silicon nitride substrate ) 是由 柏小龙 于 2021-01-30 设计创作，主要内容包括：本发明公开一种氮化硅基板烧结方法。本发明提供的一种氮化硅基板烧结方法,通过将500g～600g氮化硅粉末、20g～25g氧化锆粉末、10g～15g氧化铝粉末以及10g～15g氧化钆粉末混合均匀后加入10g～12g聚乙烯醇缩丁醛、9g～12g邻苯二甲酸二丁酯、15g～20g聚乙二醇以及10g～15g硬脂酸,进行球磨工艺、脱泡处理,将生坯在氮气中进行脱脂和预烧结,将预烧结后的生坯进行进一步烧结,冷却后得到氮化硅基板,解决了大尺寸基板在烧结过程中易变形,不致密等缺陷,从而可得到平整度达到+-0.002mm,致密度达到99％的大尺寸超薄氮化硅基板。(The invention discloses a sintering method of a silicon nitride substrate. The invention provides a silicon nitride substrate sintering method, which comprises the steps of uniformly mixing 500 g-600 g of silicon nitride powder, 20 g-25 g of zirconium oxide powder, 10 g-15 g of aluminum oxide powder and 10 g-15 g of gadolinium oxide powder, adding 10 g-12 g of polyvinyl butyral, 9 g-12 g of dibutyl phthalate, 15 g-20 g of polyethylene glycol and 10 g-15 g of stearic acid, carrying out ball milling process and defoaming treatment, degreasing and presintering the green bodies in nitrogen, further sintering the presintering green bodies, and cooling to obtain the silicon nitride substrate.)

1. A method for sintering a silicon nitride substrate, comprising the steps of:

step one, weighing 500 g-600 g of silicon nitride powder, adding 20 g-25 g of zirconium oxide powder, 10 g-15 g of aluminum oxide powder and 10 g-15 g of gadolinium oxide powder into the silicon nitride powder, and uniformly mixing to obtain mixed powder;

step two, adding 10 to 12g of polyvinyl butyral, 9 to 12g of dibutyl phthalate, 15 to 20g of polyethylene glycol and 10 to 15g of stearic acid into the mixed powder;

step three, taking 100 g-150 g of silicon nitride balls as a ball milling medium, and carrying out a ball milling process with a ball milling speed of 75-80 r/min for 18-22 h;

step four, defoaming the ball-milled material at the vacuum degree of 0.05-0.1 Pa to obtain casting slurry;

fifthly, preparing the casting slurry into a green body, degreasing and presintering the green body in nitrogen, wherein the presintering temperature is 1520 ℃, the presintering time is 2.5 hours, and the presintering gas flow is 1L/min;

step six, heating the pre-sintered green body to 1630 ℃ at a heating rate of 14 ℃/min, and preserving heat for 2h, wherein the heating process is carried out in a flowing nitrogen atmosphere sintering furnace with the atmosphere of 1 atm;

and seventhly, heating to 1750 ℃ at a heating rate of 10 ℃/min, heating to 1900 ℃ at a heating rate of 5 ℃/min, preserving heat for 2h, cooling to 1600 ℃ at a cooling rate of 1 ℃/min, and cooling to obtain the silicon nitride substrate.

2. The method of claim 1, wherein in step one, the silicon nitride powder is 500g, the zirconia powder is 25g, the alumina powder is 12g, and the gadolinia powder is 14 g.

3. The method of claim 1, wherein in the second step, the polyvinyl butyral is 12g, the dibutyl phthalate is 10g, the polyethylene glycol is 15g, and the stearic acid is 15 g.

4. The method of claim 1, wherein in step three, the ball milling media is 125 g.

5. The method for sintering a silicon nitride substrate according to claim 4, wherein in the third step, the ball milling process is 20 hours, and the ball milling rate is 75 rpm.

6. The method of claim 1, wherein the defoaming treatment is performed in a vacuum of 0.1Pa in the fourth step.

7. The method of claim 1, wherein in the step five, after the casting slurry is made into a green body, the method further comprises: drying the green body for 4 hours at 23 ℃ to obtain a biscuit, cutting the biscuit, degreasing and presintering the cut biscuit in nitrogen, and cooling to room temperature to obtain a presintering green body.

Technical Field

The invention relates to the technical field of silicon nitride substrate sintering, in particular to a silicon nitride substrate sintering method.

Background

Silicon nitride is an important structural ceramic material, has high hardness, self lubricating property and wear resistance, and is an atomic crystal; is resistant to oxidation at high temperature. It can resist cold and hot impact, and can be heated to above 1000 deg.C in air, and can be rapidly cooled and then rapidly heated, and can not be broken. The silicon nitride substrate has high strength and fracture toughness at high temperature, high heat dissipation coefficient, thermal expansion coefficient matched with a chip and extremely high thermal shock resistance. The equipment using the silicon nitride ceramic substrate can further reduce the volume, and has extremely high chemical corrosion resistance and good wear resistance. At present, only a few colleges and scientific research institutions are engaged in related research and development and technical attack of silicon nitride substrate sintering in China, and the silicon nitride substrate on the existing domestic market has the defects that a large-size substrate is easy to deform and not compact in the sintering process. Therefore, it is necessary to provide a sintering method for silicon nitride substrate to solve the above problems.

Disclosure of Invention

The invention aims to provide a silicon nitride substrate sintering method, which aims to solve the problems that a large-size substrate on the existing domestic market is easy to deform and not compact in the sintering process.

The invention provides a silicon nitride substrate sintering method, which comprises the following steps:

step one, weighing 500 g-600 g of silicon nitride powder, adding 20 g-25 g of zirconium oxide powder, 10 g-15 g of aluminum oxide powder and 10 g-15 g of gadolinium oxide powder into the silicon nitride powder, and uniformly mixing to obtain mixed powder;

step two, adding 10 to 12g of polyvinyl butyral, 9 to 12g of dibutyl phthalate, 15 to 20g of polyethylene glycol and 10 to 15g of stearic acid into the mixed powder;

step three, taking 100 g-150 g of silicon nitride balls as a ball milling medium, and carrying out a ball milling process with a ball milling speed of 75-80 r/min for 18-22 h;

step four, defoaming the ball-milled material at the vacuum degree of 0.05-0.1 Pa to obtain casting slurry;

fifthly, preparing the casting slurry into a green body, degreasing and presintering the green body in nitrogen, wherein the presintering temperature is 1520 ℃, the presintering time is 2.5 hours, and the presintering gas flow is 1L/min;

step six, heating the pre-sintered green body to 1630 ℃ at a heating rate of 14 ℃/min, and preserving heat for 2h, wherein the heating process is carried out in a flowing nitrogen atmosphere sintering furnace with the atmosphere of 1 atm;

and seventhly, heating to 1750 ℃ at a heating rate of 10 ℃/min, heating to 1900 ℃ at a heating rate of 5 ℃/min, preserving heat for 2h, cooling to 1600 ℃ at a cooling rate of 1 ℃/min, and cooling to obtain the silicon nitride substrate.

In the first step, 500g of silicon nitride powder, 25g of zirconia powder, 12g of alumina powder and 14g of gadolinium oxide powder are used.

In the second step, 12g of the polyvinyl butyral, 10g of the dibutyl phthalate, 15g of the polyethylene glycol and 15g of the stearic acid are used.

Further, in the third step, the ball milling medium is 125 g.

Further, in the third step, the ball milling process is 20 hours, and the ball milling speed is 75 revolutions per minute.

Further, in the fourth step, the defoaming treatment was performed under a vacuum of 0.1 Pa.

Further, in the fifth step, after the casting slurry is made into a green body, the method further includes: drying the green body for 4 hours at 23 ℃ to obtain a biscuit, cutting the biscuit, degreasing and presintering the cut biscuit in nitrogen, and cooling to room temperature to obtain a presintering green body.

The invention has the following beneficial effects: the invention provides a silicon nitride substrate sintering method, which comprises the steps of uniformly mixing 500 g-600 g of silicon nitride powder, 20 g-25 g of zirconium oxide powder, 10 g-15 g of aluminum oxide powder and 10 g-15 g of gadolinium oxide powder, adding 10 g-12 g of polyvinyl butyral, 9 g-12 g of dibutyl phthalate, 15 g-20 g of polyethylene glycol and 10 g-15 g of stearic acid, using 100 g-150 g of silicon nitride balls as ball milling media, performing a ball milling process for 18 h-22 h at a ball milling speed of 75-80 r/min, and performing defoaming treatment on the materials after the ball milling at a vacuum degree of 0.05-0.1 Pa to obtain casting slurry; preparing the casting slurry into a green body, degreasing and presintering the green body in nitrogen, wherein the presintering temperature is 1520 ℃, the presintering time is 2.5 hours, and the presintering gas flow is 1L/min; heating the pre-sintered green body to 1630 ℃ at a heating rate of 14 ℃/min, and keeping the temperature for 2h, wherein the heating process is carried out in a flowing nitrogen atmosphere sintering furnace with the atmosphere of 1 atm; the temperature is increased to 1750 ℃ at the temperature increasing speed of 10 ℃/min, then is increased to 1900 ℃ at the temperature increasing speed of 5 ℃/min, is kept warm for 2h, is reduced to 1600 ℃ at the temperature reducing speed of 1 ℃/min, and is cooled to obtain the silicon nitride substrate, so that the defects that the large-size substrate is easy to deform and not compact in the sintering process are overcome, and the large-size ultrathin silicon nitride substrate with the flatness of +/-0.002 mm and the density of 99% can be obtained.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a flow chart of a sintering method of a silicon nitride substrate according to the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. 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 application belongs.

Referring to fig. 1, an embodiment of the invention provides a method for sintering a silicon nitride substrate, including the following steps:

step one, weighing 500 g-600 g of silicon nitride powder, adding 20 g-25 g of zirconium oxide powder, 10 g-15 g of aluminum oxide powder and 10 g-15 g of gadolinium oxide powder into the silicon nitride powder, and uniformly mixing to obtain mixed powder.

Specifically, zirconia is a main oxide of zirconium, and is generally a white odorless and tasteless crystal, which is poorly soluble in water, hydrochloric acid, and dilute sulfuric acid. The chemical property is inactive, and the material has the properties of high melting point, high resistivity, high refractive index and low thermal expansion coefficient, so that the material becomes an important high temperature resistant material, a ceramic insulating material and a ceramic opacifier, and is also a main raw material of the artificial drill. Alumina is a stable oxide of aluminum, also known as alumina in mining, ceramics and materials science, and is a white solid that is poorly soluble in water, odorless, tasteless, extremely hard in quality, and easily absorbs moisture without deliquescing (burned does not absorb moisture). Alumina is a typical amphoteric oxide, can be dissolved in inorganic acid and alkaline solutions, is hardly dissolved in water and a nonpolar organic solvent, and is commonly used as an analytical reagent, dehydration of an organic solvent, an adsorbent, an organic reaction catalyst, an abrasive, a polishing agent, a raw material for aluminum smelting, and a refractory material. The gadolinium oxide is prepared from monazite or mixed rare earth ore by extraction and other purification steps. The gadolinium oxyfluoride is prepared by using oxalic acid to precipitate gadolinium oxalate, and the gadolinium oxyfluoride is prepared by separation, drying and firing, and is commonly used as yttrium aluminum and yttrium iron garnet doping agents, intensifying fluorescent materials in medical instruments, nuclear reactor control materials, raw materials for preparing metal gadolinium, magnetic bubble materials, optical prism additives and the like. In the invention, 20 g-25 g of zirconia powder, 10 g-15 g of alumina powder and 10 g-15 g of gadolinium oxide powder are added into the silicon nitride powder as sintering aids, so that the sintering effect is good.

And step two, adding 10 to 12g of polyvinyl butyral, 9 to 12g of dibutyl phthalate, 15 to 20g of polyethylene glycol and 10 to 15g of stearic acid into the mixed powder.

Specifically, polyvinyl butyral (PVB) is a product of condensation of polyvinyl alcohol and butyraldehyde under acid catalysis. PVB molecules contain longer branched chains, so that the PVB has good flexibility, low glass transition temperature and high tensile strength and impact strength; PVB has excellent transparency, good solubility, good light resistance, water resistance, heat resistance, cold resistance and film forming property; the functional group contained in it can be used for saponification reaction of phthalidyl, acetification reaction of phthalidyl, sulfonation reaction of phthalidyl and other various reactions; has high adhesion with materials such as glass, metal (especially aluminum), and the like. Therefore, the resin is widely applied to the fields of manufacturing laminated safety glass, adhesives, ceramic stained paper, aluminum foil paper, electrical equipment materials, glass fiber reinforced plastic products, fabric treating agents and the like, and becomes an indispensable synthetic resin material. Dibutyl phthalate is the most commonly used plasticizer for polyvinyl chloride and gives good flexibility but is less durable due to its greater volatility and water extraction. Dibutyl phthalate is an excellent plasticizer of nitrocellulose, has strong gelation ability, is used for nitrocellulose coating, and has good softening effect. The stability, flexing resistance, cohesiveness and waterproofness of the plasticizer are all superior to those of other plasticizers. Dibutyl phthalate can also be used as a plasticizer for polyvinyl acetate, alkyd resins, nitrocellulose, ethylcellulose, neoprene, and nitrile rubber. Polyethylene glycol is a high molecular polymer, has no irritation, slightly bitter taste, good water solubility, and good compatibility with many organic components. Has excellent lubricity, moisture retention, dispersibility and bonding agent, can be used as an antistatic agent, a softening agent and the like, and has extremely wide application in the industries of cosmetics, pharmacy, chemical fiber, rubber, plastics, papermaking, paint, electroplating, pesticides, metal processing, food processing and the like. Stearic acid is a compound, namely octadecanoic acid, produced by hydrolysis of fats and oils, and is mainly used for producing stearate. According to the invention, 10-12 g of polyvinyl butyral, 9-12 g of dibutyl phthalate, 15-20 g of polyethylene glycol, 10-15 g of stearic acid and other high molecular compounds are added into the mixed powder, so that the ball milling effect is improved.

And step three, performing a ball milling process with a ball milling speed of 75-80 r/min for 18-22 h by taking 100-150 g of silicon nitride balls as a ball milling medium.

And step four, defoaming the ball-milled material at the vacuum degree of 0.05-0.1 Pa to obtain casting slurry.

And step five, preparing the casting slurry into a green body, degreasing and presintering the green body in nitrogen, wherein the presintering temperature is 1520 ℃, the presintering time is 2.5 hours, and the presintering gas flow is 1L/min.

And step six, heating the pre-sintered green body to 1630 ℃ at the heating rate of 14 ℃/min, and preserving heat for 2h, wherein the heating process is carried out in a flowing nitrogen atmosphere sintering furnace with the atmosphere of 1 atm.

And seventhly, heating to 1750 ℃ at a heating rate of 10 ℃/min, heating to 1900 ℃ at a heating rate of 5 ℃/min, preserving heat for 2h, cooling to 1600 ℃ at a cooling rate of 1 ℃/min, and cooling to obtain the silicon nitride substrate.

Specific examples are as follows.

The first embodiment is as follows:

500g of silicon nitride powder was weighed, and 25g of zirconia powder, 12g of alumina powder and 14g of gadolinium oxide powder were added to the silicon nitride powder and mixed uniformly to obtain a mixed powder. To the mixed powder were added 12g of polyvinyl butyral, 10g of dibutyl phthalate, 15g of polyethylene glycol and 15g of stearic acid. 100g of silicon nitride balls are used as a ball milling medium, and a ball milling process with the ball milling speed of 75 r/min is carried out for 18 h. And (4) defoaming the material after the ball milling is finished under the vacuum degree of 0.1Pa to obtain casting slurry. Preparing the casting slurry into a green body, drying the green body for 4 hours at 23 ℃ to obtain a green body, cutting the green body, degreasing and presintering the cut green body in nitrogen, cooling to room temperature to obtain a presintering green body, degreasing and presintering the green body in nitrogen, wherein the presintering temperature is 1520 ℃, the presintering time is 2.5 hours, and the presintering gas flow is 1L/min. And (3) heating the pre-sintered green body to 1630 ℃ at the heating rate of 14 ℃/min, preserving the temperature for 2h, and carrying out the heating process in a flowing nitrogen atmosphere sintering furnace with the atmosphere of 1 atm. Heating to 1750 ℃ at a heating rate of 10 ℃/min, heating to 1900 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 2h, cooling to 1600 ℃ at a cooling rate of 1 ℃/min, and cooling to obtain the silicon nitride substrate.

Example two:

500g of silicon nitride powder was weighed, and 20g of zirconia powder, 15g of alumina powder and 10g of gadolinium oxide powder were added to the silicon nitride powder and mixed uniformly to obtain a mixed powder. To the mixed powder were added 10g of polyvinyl butyral, 9g of dibutyl phthalate, 15g of polyethylene glycol and 10g of stearic acid. And (3) performing a ball milling process with a ball milling speed of 75 r/min for 20h by taking 125g of silicon nitride balls as a ball milling medium. And (4) defoaming the material after the ball milling is finished under the vacuum degree of 0.05Pa to obtain casting slurry. Preparing the casting slurry into a green body, drying the green body for 4 hours at 23 ℃ to obtain a green body, cutting the green body, degreasing and presintering the cut green body in nitrogen, cooling to room temperature to obtain a presintering green body, degreasing and presintering the green body in nitrogen, wherein the presintering temperature is 1520 ℃, the presintering time is 2.5 hours, and the presintering gas flow is 1L/min. And (3) heating the pre-sintered green body to 1630 ℃ at the heating rate of 14 ℃/min, preserving the temperature for 2h, and carrying out the heating process in a flowing nitrogen atmosphere sintering furnace with the atmosphere of 1 atm. Heating to 1750 ℃ at a heating rate of 10 ℃/min, heating to 1900 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 2h, cooling to 1600 ℃ at a cooling rate of 1 ℃/min, and cooling to obtain the silicon nitride substrate.

Example three:

600g of silicon nitride powder was weighed, and 25g of zirconia powder, 15g of alumina powder, and 15g of gadolinium oxide powder were added to the silicon nitride powder and mixed uniformly to obtain a mixed powder. To the mixed powder were added 12g of polyvinyl butyral, 12g of dibutyl phthalate, 20g of polyethylene glycol and 15g of stearic acid. 150g of silicon nitride balls are used as a ball milling medium, and a ball milling process with the ball milling speed of 80 r/min is carried out for 22 h. And (4) defoaming the material after the ball milling is finished under the vacuum degree of 0.1Pa to obtain casting slurry. Preparing the casting slurry into a green body, drying the green body for 4 hours at 23 ℃ to obtain a green body, cutting the green body, degreasing and presintering the cut green body in nitrogen, cooling to room temperature to obtain a presintering green body, degreasing and presintering the green body in nitrogen, wherein the presintering temperature is 1520 ℃, the presintering time is 2.5 hours, and the presintering gas flow is 1L/min. And (3) heating the pre-sintered green body to 1630 ℃ at the heating rate of 14 ℃/min, preserving the temperature for 2h, and carrying out the heating process in a flowing nitrogen atmosphere sintering furnace with the atmosphere of 1 atm. Heating to 1750 ℃ at a heating rate of 10 ℃/min, heating to 1900 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 2h, cooling to 1600 ℃ at a cooling rate of 1 ℃/min, and cooling to obtain the silicon nitride substrate.

Example four:

450g of silicon nitride powder was weighed, 18g of zirconia powder, 12g of alumina powder and 13g of gadolinium oxide powder were added to the silicon nitride powder, and mixed uniformly to obtain a mixed powder. To the mixed powder were added 11g of polyvinyl butyral, 9g of dibutyl phthalate, 12g of polyethylene glycol and 12g of stearic acid. 135g of silicon nitride balls are used as a ball milling medium, and a ball milling process with the ball milling speed of 72 r/min is carried out for 23 h. And (3) defoaming the material after the ball milling is finished under the vacuum degree of 0.09Pa to obtain casting slurry. Preparing the casting slurry into a green body, drying the green body for 4 hours at 23 ℃ to obtain a green body, cutting the green body, degreasing and presintering the cut green body in nitrogen, cooling to room temperature to obtain a presintering green body, degreasing and presintering the green body in nitrogen, wherein the presintering temperature is 1520 ℃, the presintering time is 2.5 hours, and the presintering gas flow is 1L/min. And (3) heating the pre-sintered green body to 1630 ℃ at the heating rate of 14 ℃/min, preserving the temperature for 2h, and carrying out the heating process in a flowing nitrogen atmosphere sintering furnace with the atmosphere of 1 atm. Heating to 1750 ℃ at a heating rate of 10 ℃/min, heating to 1900 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 2h, cooling to 1600 ℃ at a cooling rate of 1 ℃/min, and cooling to obtain the silicon nitride substrate.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.