阅读说明：本技术 一种宽工作温区的电子陶瓷复合基片的制备工艺 (Preparation process of electronic ceramic composite substrate with wide working temperature zone ) 是由 晏志新 于 2021-07-30 设计创作，主要内容包括：本发明公开一种宽工作温区的电子陶瓷复合基片的制备工艺,涉及电子陶瓷加工技术领域。本发明公开的电子陶瓷复合基片的制备工艺为：将钛酸四丁酯、碳酸镁、硝酸钬、七水氢氧化锶和硅酸锂混合加入溶剂中水解、聚合,然后加入脂肪醇聚氧乙烯醚和三乙醇胺油酸皂混合,在一定条件下反应后,烧结,制得钛酸锶基陶瓷粉末；将表面改性后的钛酸锶基陶瓷粉末与聚酰亚胺溶液采用流延工艺涂覆,进行阶梯式固化,制得电子陶瓷复合基片。本发明提供的电子陶瓷复合基片制备工艺简单易操作,复合基片表面平整,不易脆断,并且机械强度高、韧性好,还具有高的介电常数、低的介电损耗,在较宽的工作温区内仍具有较好的介电性能。(The invention discloses a preparation process of an electronic ceramic composite substrate with a wide working temperature zone, and relates to the technical field of electronic ceramic processing. The invention discloses a preparation process of an electronic ceramic composite substrate, which comprises the following steps: mixing tetrabutyl titanate, magnesium carbonate, holmium nitrate, strontium hydroxide heptahydrate and lithium silicate, adding the mixture into a solvent for hydrolysis and polymerization, then adding fatty alcohol-polyoxyethylene ether and triethanolamine oleate soap for mixing, reacting under certain conditions, and sintering to prepare strontium titanate-based ceramic powder; and coating the surface-modified strontium titanate-based ceramic powder and the polyimide solution by adopting a tape casting process, and performing stepped curing to obtain the electronic ceramic composite substrate. The electronic ceramic composite substrate provided by the invention has the advantages of simple and easy operation process, flat surface, difficult brittle fracture, high mechanical strength, good toughness, high dielectric constant, low dielectric loss and good dielectric property in a wider working temperature region.)

1. A preparation process of an electronic ceramic composite substrate with a wide working temperature zone is characterized by comprising the following steps:

(1) uniformly mixing a 45 wt% acetic acid solution and absolute ethyl alcohol according to a certain volume ratio, then sequentially adding tetrabutyl titanate, magnesium carbonate, holmium nitrate, strontium hydroxide heptahydrate and lithium silicate while stirring, stirring for 1-2 h for hydrolysis, then adding fatty alcohol-polyoxyethylene ether and triethanolamine oleate soap, and stirring for 30min to prepare a mixed solution;

(2) placing the mixed solution in a reaction kettle, stirring and reacting for 10-15 h at 70-80 ℃, adjusting the pH value to 7-7.5 by adopting a 20 wt% NaOH solution, then heating to 120-140 ℃, reacting for 2-3 h, filtering, washing with deionized water for three times, and centrifuging to obtain a wet filter cake;

(3) adding the wet filter cake into a drying oven, drying at the temperature of 110-;

(4) placing the strontium titanate-based ceramic material in a ball mill, adding a proper amount of absolute ethyl alcohol as a ball milling medium, carrying out ball milling, drying, and sieving with a 800-mesh sieve to obtain strontium titanate-based ceramic powder;

(5) adding proper amount of 98 percent concentrated sulfuric acid and 20 percent by weight of H into the strontium titanate-based ceramic powder₂O₂Stirring the mixed liquid of water at 80-90 ℃ for reaction for 0.5-1 h, then slowly adding a proper amount of chitosan hydrochloride solution, continuously stirring for 6-8 h at the temperature, washing with deionized water, and centrifugally drying to obtain the modified strontium titanate-based ceramic;

(6) dimethylformamide and tetrahydrofuran were mixed in a ratio of 3: 1, then adding a proper amount of soluble polyimide, and stirring until the soluble polyimide is dissolved to obtain a polyimide solution;

(7) placing the modified strontium titanate-based ceramic in a reaction kettle, adding a proper amount of dimethylformamide solvent, stirring for 1h at 70-80 ℃, then slowly adding polyimide solution while stirring, stirring for reacting for 8-10 h, heating to 120-.

2. The process for preparing an electronic ceramic composite substrate with a wide working temperature zone according to claim 1, wherein the volume ratio of the 45 wt% acetic acid solution to the absolute ethyl alcohol is (3-4): 1.

3. the process for preparing an electronic ceramic composite substrate with a wide working temperature zone according to claim 1, wherein the mass-to-liquid ratio in the mixed solution is 0.12-0.18 g/mL.

4. The process for preparing an electronic ceramic composite substrate with a wide operating temperature range according to claim 1, wherein in the step (5), the mixed liquid contains 98% concentrated sulfuric acid and 20 wt% H₂O₂The water volume ratio is 2: 1, the mass-to-liquid ratio of the strontium titanate-based ceramic powder to the mixed liquid is 0.2-0.3 g/mL.

5. The process for preparing the electronic ceramic composite substrate with the wide working temperature area according to claim 1, wherein the mass concentration of the chitosan hydrochloride solution is 40-60%, and the mass-to-liquid ratio of the strontium titanate-based ceramic powder to the chitosan hydrochloride solution is 0.8-1 g/mL.

6. The preparation process of the high-temperature-resistant electronic ceramic composite material according to claim 1, wherein the mass ratio of the strontium hydroxide heptahydrate to the tetrabutyl titanate is 1: (0.8-1.2);

the mass ratio of the strontium hydroxide heptahydrate to the magnesium carbonate is 1: (0.18-0.22);

the mass ratio of the strontium hydroxide heptahydrate to the holmium nitrate is 1: (0.05-0.09);

the mass ratio of the strontium hydroxide heptahydrate to the lithium silicate is 1: (0.20-0.32);

the mass ratio of the strontium hydroxide heptahydrate to the fatty alcohol-polyoxyethylene ether is 1: (0.03-0.05);

the mass ratio of the strontium hydroxide heptahydrate to the triethanolamine oleic soap is 1: (0.01-0.03).

7. The process for preparing an electronic ceramic composite substrate with a wide working temperature zone according to claim 1, wherein the mass-to-liquid ratio of the polyimide solution is 1.5-2 g/mL.

8. The process for preparing an electronic ceramic composite substrate with a wide operating temperature range according to claim 1, wherein the amount of the soluble polyimide added is 45-55% of the strontium titanate-based ceramic powder.

9. The process for preparing an electronic ceramic composite substrate with a wide working temperature zone according to claim 1, wherein in the step-type curing process, the temperature rise program of a muffle furnace is set as follows: 120 ℃/2h, 160 ℃/1h, 200 ℃/40min, 260 ℃/30min, 320 ℃/30min, 350 ℃/10 min.

Technical Field

The invention belongs to the technical field of electronic ceramic processing, and particularly relates to a preparation process of an electronic ceramic composite substrate with a wide working temperature zone.

Background

SrTiO₃The ceramic is an excellent dielectric material as a quantum paraelectric ceramic, and belongs to a typical ABO₃The perovskite structure has the advantages of good bias voltage stability, low dielectric loss, high breakdown field strength and good performanceTemperature, frequency, but with a dielectric constant of about 300, cannot meet the requirements of its dielectric application. Now SrTiO₃Modification studies of ceramics are mainly in three aspects: firstly, SrTiO₃With high dielectric constant BaTiO₃Or PbTiO₃The ceramic is solid-dissolved to form a solid solution, the dielectric constant of the ceramic can be changed within 290-2000, the dielectric loss is less than 0.01, but the breakdown field intensity is reduced, the temperature, frequency and bias voltage dependence is enhanced, and the use range of the temperature is reduced; secondly, rare earth elements or Bi are adopted³⁺Plasma doping of SrTiO₃Ceramics, which have a large dielectric constant (10000), a large dielectric loss (0.1), and poor temperature and frequency stability of dielectric properties; thirdly, adopting donor doping SrTiO at B position₃Ceramics, the B-site doping ions generally being higher valent ions, e.g. Nb⁵⁺And the change of the dielectric property is related to oxygen vacancy, and different dielectric relaxation peaks appear in different temperature ranges, so that the change of the dielectric constant and the dielectric loss is large under the state of being lower than the normal temperature and higher than the normal temperature, namely the temperature and frequency stability of the dielectric property are poor. With the rapid development of the information technology industry, especially the electronics and microelectronics industry, higher requirements are put forward on dielectric ceramic materials, and therefore, how to develop a high dielectric constant, low dielectric loss and good temperature stability for operating in a wider temperature range becomes one of the current research hotspots.

SrTiO₃The ceramic substrate is generally formed by forming a substrate blank by adopting a tape casting process and then performing high-temperature densification sintering, and has the characteristics of thinness, softness, brittleness, tilting and the like. SrTiO₃The ceramic substrate is soft and brittle, has low bending strength, tensile strength and fracture toughness, and has poor wear resistance, mainly because the grain boundary layer is thin, ceramic crystal particles are combined by chemical bonds, the chemical bonds have directionality, the atom stacking density is low, the atom distance is large, and the brittleness index is high, so that brittle fracture damage is easily generated. In the prior art, the strength and the toughness of the material are improved mainly by adding a sintering aid and doping metal ions or rare earth elements, and the grain size and the bonding force among grains are adjusted, but in the sintering process, due to materials and air holesThe gas expansion in the process and the defects formed by vacancy, distortion, local stress and the like in the blank can drive the action, so that the surface of the sintered ceramic substrate is uneven, and the local strength and brittleness are influenced, thereby influencing the SrTiO₃The service life of the ceramic substrate.

Inorganic/organic composite materials are increasingly becoming a hot point of research because they retain the characteristics of functional phases of inorganic materials and also possess the processing characteristics specific to polymers, such as lower processing temperature, excellent processing characteristics, etc. The traditional organic polymer dielectric material has the characteristics of high pressure resistance, good flexibility, high mechanical strength and the like, but the dielectric constant is low, so that the requirement of the current society on the electronic energy storage performance cannot be met. Thus, how to combine organic polymer dielectric materials with SrTiO₃The ceramic is combined to prepare the composite material with high strength, good toughness, high dielectric constant and low dielectric loss, and the dielectric property of the composite material can work in a wider temperature range, which becomes the main research work of the invention.

Disclosure of Invention

The invention mainly aims to provide a preparation process of an electronic ceramic composite substrate with a wide working temperature area, which is simple and easy to operate, and the prepared electronic ceramic composite substrate has the advantages of flat surface, difficult brittle fracture, high mechanical strength, good toughness, high dielectric constant, low dielectric loss and good dielectric property in the wide working temperature area.

In order to realize the purpose of the invention, the invention provides a preparation process of an electronic ceramic composite substrate with a wide working temperature zone, which specifically comprises the following steps:

(1) uniformly mixing a 45 wt% acetic acid solution and absolute ethyl alcohol according to a certain volume ratio, then sequentially adding tetrabutyl titanate, magnesium carbonate, holmium nitrate, strontium hydroxide heptahydrate and lithium silicate while stirring, stirring for 1-2 h for hydrolysis, then adding fatty alcohol-polyoxyethylene ether and triethanolamine oleate soap, and stirring for 30min to prepare a mixed solution;

(2) placing the mixed solution in a reaction kettle, stirring and reacting for 10-15 h at 70-80 ℃, adjusting the pH value to 7-7.5 by adopting a 20 wt% NaOH solution, then heating to 120-140 ℃, reacting for 2-3 h, filtering, washing with deionized water for three times, and centrifuging to obtain a wet filter cake;

(3) adding the wet filter cake into a drying oven, drying at the temperature of 110-;

(4) placing the strontium titanate-based ceramic material in a ball mill, adding a proper amount of absolute ethyl alcohol as a ball milling medium, carrying out ball milling, drying, and sieving with a 800-mesh sieve to obtain strontium titanate-based ceramic powder;

(5) adding proper amount of 98 percent concentrated sulfuric acid and 20 percent by weight of H into the strontium titanate-based ceramic powder₂O₂Stirring the mixed liquid of water at 80-90 ℃ for reaction for 0.5-1 h, then slowly adding a proper amount of chitosan hydrochloride solution, continuously stirring for 6-8 h at the temperature, washing with deionized water, and centrifugally drying to obtain the modified strontium titanate-based ceramic;

(6) dimethylformamide (DMF) and Tetrahydrofuran (THF) were mixed at 3: 1, then adding a proper amount of soluble polyimide, and stirring until the soluble polyimide is dissolved to obtain a polyimide solution;

(7) placing the modified strontium titanate-based ceramic in a reaction kettle, adding a proper amount of dimethylformamide solvent, stirring for 1h at 70-80 ℃, then slowly adding polyimide solution while stirring, stirring for reacting for 8-10 h, heating to 120-.

Further, the volume ratio of the 45 wt% acetic acid solution to the absolute ethyl alcohol is (3-4): 1.

further, the mass-to-liquid ratio in the mixed solution is 0.12-0.18 g/mL.

Further, in the step (5), 98% concentrated sulfuric acid and 20 wt% H in the mixed liquid₂O₂The water volume ratio is 2: 1, said strontium titanate groupThe mass-liquid ratio of the ceramic powder to the mixed liquid is 0.2-0.3 g/mL.

Further, the mass concentration of the chitosan hydrochloride solution is 40-60%, and the mass-to-liquid ratio of the strontium titanate-based ceramic powder to the chitosan hydrochloride solution is 0.8-1 g/mL.

Further, the mass ratio of the strontium hydroxide heptahydrate to the tetrabutyl titanate is 1: (0.8-1.2);

the mass ratio of the strontium hydroxide heptahydrate to the magnesium carbonate is 1: (0.18-0.22);

the mass ratio of the strontium hydroxide heptahydrate to the holmium nitrate is 1: (0.05-0.09);

the mass ratio of the strontium hydroxide heptahydrate to the lithium silicate is 1: (0.20-0.32);

the mass ratio of the strontium hydroxide heptahydrate to the fatty alcohol-polyoxyethylene ether is 1: (0.03-0.05);

the mass ratio of the strontium hydroxide heptahydrate to the triethanolamine oleic soap is 1: (0.01-0.03).

Further, the mass-to-liquid ratio of the polyimide solution is 1.5-2 g/mL.

Further, the adding amount of the soluble polyimide is 45-55% of the mass of the strontium titanate-based ceramic powder.

Further, in the step-type curing process, the temperature rise program of the muffle furnace is set as follows: 120 ℃/2h, 160 ℃/1h, 200 ℃/40min, 260 ℃/30min, 320 ℃/30min, 350 ℃/10 min.

The invention achieves the following beneficial effects:

1. in the chemical preparation process of the strontium titanate-based ceramic material, in the mixed solvent condition of acetic acid and absolute ethyl alcohol, tetrabutyl titanate, magnesium carbonate, holmium nitrate, strontium hydroxide heptahydrate and lithium silicate are subjected to chemical hydrolysis and polymerization reaction to form a strontium titanate-based mixed solution, and the strontium titanate-based ceramic material containing magnesium oxide, silicon oxide, lithium oxide and holmium oxide is prepared by combining thermal reaction and high-temperature sintering. The strontium titanate-based ceramic material and the polyimide are combined to prepare the electronic ceramic composite substrate by adopting a tape casting process, the electronic ceramic composite substrate integrates the advantages of the strontium titanate-based ceramic material and the polyimide, has high mechanical strength and toughness, is not easy to brittle failure, has excellent dielectric properties, and has higher dielectric constant and lower dielectric loss at a wider working temperature range of-60-250 ℃.

2. The invention adopts a hydrothermal method to prepare a strontium titanate-based ceramic material, which mixes magnesium carbonate, holmium nitrate, lithium silicate, tetrabutyl titanate and strontium hydroxide heptahydrate in a solvent for hydrolysis and polymerization reaction, so that the strontium titanate-based ceramic is doped with four elements of magnesium, holmium, silicon and lithium, namely Mg²⁺、Ho³⁺、Si⁴⁺、Li⁺The strontium site or the titanium site in the strontium titanate is replaced, electrons or defects are generated for compensation to form effective acceptor doping, the dielectric constant of the strontium titanate-based ceramic is obviously improved, the dielectric loss is reduced, and the strontium titanate-based ceramic still has good dielectric properties in a high working temperature range; the oxides or adulterants formed by the four elements and the strontium titanate are synthesized into the solid solution, so that the sintering temperature of the strontium titanate-based ceramic material is reduced, the abnormal growth of ceramic grains is inhibited, the strontium titanate ceramic grains are fine and uniform, the density of the strontium titanate-based ceramic is increased, the strength and the toughness of the strontium titanate-based ceramic are improved, and the strontium titanate-based ceramic is not easy to brittle failure.

3. According to the invention, the polyimide and the strontium titanate-based ceramic are compounded, and the electronic ceramic composite substrate is prepared by a tape casting process at a lower temperature, so that the toughness of the electronic ceramic composite substrate is improved, the surface of the ceramic substrate is flat and smooth and is not easy to brittle failure, and the qualification rate of the electronic ceramic composite substrate is improved.

4. According to the invention, the strontium titanate-based ceramic material is prepared by adopting a hydrothermal method and a sintering process, and is compounded with polyimide to prepare the electronic ceramic composite substrate, so that the sintering temperature is low, the toughness is good, the production cost is reduced, the production qualification rate and the use effect are improved, the preparation method is easy to operate, and the electronic ceramic composite substrate with high dielectric property and reliable quality can be obtained.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the 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 embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The soluble polyimide of the present invention is a PI polyimide resin with a U.S. dupont designation of 100 HN.

The invention provides a preparation process of an electronic ceramic composite substrate with a wide working temperature zone, which specifically comprises the following steps:

(1) uniformly mixing a 45 wt% acetic acid solution and absolute ethyl alcohol according to a certain volume ratio, then sequentially adding tetrabutyl titanate, magnesium carbonate, holmium nitrate, strontium hydroxide heptahydrate and lithium silicate while stirring, stirring for 1-2 h for hydrolysis, then adding fatty alcohol-polyoxyethylene ether and triethanolamine oleate soap, and stirring for 30min to prepare a mixed solution.

The mixed solution of 45 wt% acetic acid solution and absolute ethyl alcohol is used as the solvent of tetrabutyl titanate, magnesium carbonate, holmium nitrate, strontium hydroxide heptahydrate and lithium silicate, has good solubility, can accelerate the hydrolysis of the substances, and plays a role in promoting the hydrolysis and polymerization of the whole mixed system. Under the acidic condition, a strontium titanate-based composite precursor is formed through chemical hydrolysis and polymerization reaction among tetrabutyl titanate, magnesium carbonate, holmium nitrate, strontium hydroxide heptahydrate and lithium silicate, then under the action of an anionic surfactant and a dispersing agent, all components in a mixed solution are uniformly dispersed, and the binding force among all components after the hydrolysis and polymerization reaction can be improved, so that all components are not easy to agglomerate, are uniformly dispersed and are tightly combined, the subsequent heat treatment and sintering processes are facilitated, the binding force among the strontium titanate-based composite components is increased, the porosity of barium titanate-based ceramics is reduced, and the density, strength and toughness of the strontium titanate-based ceramics are improved.

(2) And (3) placing the mixed solution into a reaction kettle, stirring and reacting for 10-15 h at 70-80 ℃, adjusting the pH value to 7-7.5 by using a 20 wt% NaOH solution, then heating to 120-140 ℃, reacting for 2-3 h, filtering, washing with deionized water for three times, and centrifuging to obtain a wet filter cake. Reacting the strontium titanate-based precursor at high temperature to ensure that all raw materials are completely reacted, removing most acetic acid and ethanol, and removing unreacted residual substances to prepare the strontium titanate-based compound doped with Mg, Si, Li and Ho compounds.

(3) And (3) adding the wet filter cake into an oven, drying at the temperature of 110-120 ℃ for 3-5 h, and then sintering at the sintering temperature of 900-1000 ℃ for 5-8 h to obtain the strontium titanate-based ceramic material. And sintering the strontium titanate-based composite doped with Mg, Si, Li and Ho at high temperature to prepare the strontium titanate-based ceramic material containing magnesium oxide, silicon oxide, lithium oxide and holmium oxide.

MgO、SiO₂And Li₂The addition of O inhibits the abnormal growth of strontium titanate crystal grains, so that the size of the ceramic crystal grains is uniform, the densification process of the ceramic is promoted, and the discharge of air holes among the crystal grains is promoted, so that the strontium titanate-based ceramic disclosed by the invention forms fully-dense polycrystal, the strontium titanate ceramic forms a dense structure, the strength and the toughness of the strontium titanate-based ceramic disclosed by the invention are improved, and the strontium titanate ceramic is not easy to brittle fracture; MgO, SiO₂And Li₂The activity of O is relatively high, and the O is easy to form a solid solution with strontium titanate and holmium oxide in the sintering process, so that the sintering temperature can be reduced, the crystal diffusion and the sintering speed increase are facilitated, and the density and the mechanical property of the ceramic matrix are remarkably improved. MgO, SiO₂And Li₂The combination of the three components leads the dielectric service temperature of the invention to be widened, namely, the invention has better dielectric property and breakdown strength, higher dielectric constant and lower dielectric loss in a wider temperature working range.

The holmium oxide has good activity, is added into the invention to promote sintering, and forms a glass phase with other oxides in the sintering process, thereby being beneficial to the diffusion and the migration of a crystal boundary, inhibiting the abnormal growth of strontium titanate crystal grains, improving the density of strontium titanate ceramics and obviously improving the mechanical strength and the toughness of the invention; the addition of holmium oxide also obviously improves the dielectric constant of the invention and reduces the dielectric loss.

(4) And (2) placing the strontium titanate-based ceramic material in a ball mill, adding a proper amount of absolute ethyl alcohol as a ball milling medium, performing ball milling, drying, and screening with a 800-mesh screen to obtain strontium titanate-based ceramic powder.

(5) Adding proper amount of 98 percent concentrated sulfuric acid and 20 percent by weight of H into the strontium titanate-based ceramic powder₂O₂Stirring the mixed liquid of water at 80-90 ℃ for reaction for 0.5-1 h, then slowly adding a proper amount of chitosan hydrochloride solution, continuously stirring for 6-8 h at the temperature, washing with deionized water, and centrifugally drying to obtain the modified strontium titanate-based ceramic.

The invention uses appropriate amount of 98 percent concentrated sulfuric acid and 20 percent by weight of H₂O₂The surface of the strontium titanate-based ceramic powder is subjected to hydroxylation treatment by the mixed liquid of water, and then the hydroxylation treatment is carried out in the chitosan hydrochloride solution to obtain the surface modified strontium titanate-based ceramic, so that the interface polarization between the strontium titanate-based ceramic and an organic polymer (polyimide) matrix can be enhanced, the wettability between the strontium titanate-based ceramic and the organic polymer (polyimide) matrix is stronger, the binding force between the strontium titanate-based ceramic and the organic polymer (polyimide) matrix is improved, and the electronic ceramic composite substrate disclosed by the invention is compact in structure and not easy to break.

(6) Dimethylformamide (DMF) and Tetrahydrofuran (THF) were mixed at 3: 1, then adding a proper amount of soluble polyimide, and stirring until the soluble polyimide is dissolved to obtain a polyimide solution.

(7) Placing the modified strontium titanate-based ceramic in a reaction kettle, adding a proper amount of dimethylformamide solvent, stirring for 1h at 70-80 ℃, then slowly adding polyimide solution while stirring, stirring for reacting for 8-10 h, heating to 120-.

The polyimide has excellent comprehensive performance and heat resistance, can resist high temperature up to 400, has a long-term use temperature range of-200 to 300 ℃, has a dielectric constant of 3 to 4 and dielectric loss of about 10^－3The breakdown strength is within 1000-3000 Kv/cm, and the polyimide can maintain the dielectric property within a wide temperature and frequency rangeThe product has stable water-based property, and has high tensile strength and elastic modulus. The invention carries out in-situ polymerization reaction on the strontium titanate-based ceramic material and polyimide solution at a certain temperature after surface treatment, and then carries out curing by a tape casting process to prepare the electronic ceramic composite substrate. The polyimide and the strontium titanate-based ceramic material are combined, so that the dielectric constant of the strontium titanate-based ceramic material is reduced to a certain extent, but the electronic composite matrix still has high dielectric constant, and the dielectric loss of the electronic composite matrix is reduced; the use of the polyimide improves the long-term use temperature range of the invention, the dielectric property of the polyimide has good temperature stability, and the dielectric working temperature range is widened.

Preferably, the volume ratio of the 45 wt% acetic acid solution to the absolute ethyl alcohol is (3-4): 1. if the proportion of the acetic acid solution is too high, the polymerization effect among the components in the mixed solution is poor, and some components are more likely to react with acetic acid; if the ratio of the coarse solution to the short solution is too low, the hydrolysis effect of each component in the mixed solution is affected, and the polymerization reaction among the components is not facilitated.

Preferably, the mass-to-liquid ratio in the mixed solution is 0.12-0.18 g/mL. The mass-to-liquid ratio of the mixed solution refers to the ratio of the total mass of tetrabutyl titanate, magnesium carbonate, holmium nitrate, strontium hydroxide heptahydrate, lithium silicate, fatty alcohol-polyoxyethylene ether and triethanolamine oleate soap to the volume sum of 45 wt% acetic acid solution and absolute ethyl alcohol, and is g/mL. The invention uses the mass-liquid ratio in the range, so that each component in the mixed solution can be hydrolyzed and polymerized more effectively, and the mass-liquid ratio is too low, and the concentration of acetic acid and ethanol is too high, so that the polymerization reaction among each component of solute in the mixed solution is influenced; the mass-liquid ratio is too high, and the content of acetic acid and ethanol is too low, so that the components of the solute are not completely hydrolyzed, the polymerization reaction is further influenced, and the doping effect of the subsequent strontium titanate-based ceramic is influenced.

Preferably, in step (5), 98% concentrated sulfuric acid and 20 wt% H in the mixed liquid₂O₂The water volume ratio is 2: 1, the mass-to-liquid ratio of the strontium titanate-based ceramic powder to the mixed liquid is 0.2-0.3 g/mL. The invention selects 98% concentrated sulfuric acid with a certain proportionAnd 20 wt% of H₂O₂The water hydroxylates the strontium titanate-based ceramic powder, so that the surface of the strontium titanate-based ceramic powder can be effectively hydroxylated, and the crystal structure of the strontium titanate-based ceramic can not be influenced. If the ratio of the liquid to the medium is too high, the hydroxylation treatment is incomplete; if the mass-liquid ratio is too low, the mixed liquid will erode the internal structure of the strontium titanate-based ceramic to a certain extent, thereby affecting the mechanical property and the dielectric property of the strontium titanate-based ceramic powder.

Preferably, the mass concentration of the chitosan hydrochloride solution is 40-60%, and the mass-to-liquid ratio of the strontium titanate-based ceramic powder to the chitosan hydrochloride solution is 0.8-1 g/mL.

Preferably, the mass ratio of the strontium hydroxide heptahydrate to the tetrabutyl titanate is 1: (0.8-1.2);

the mass ratio of the strontium hydroxide heptahydrate to the magnesium carbonate is 1: (0.18-0.22);

the mass ratio of strontium hydroxide heptahydrate to holmium nitrate is 1: (0.05-0.09);

the mass ratio of the strontium hydroxide heptahydrate to the lithium silicate is 1: (0.20-0.32);

the mass ratio of the strontium hydroxide heptahydrate to the fatty alcohol-polyoxyethylene ether is 1: (0.03-0.05);

the mass ratio of the strontium hydroxide heptahydrate to the triethanolamine oleic soap is 1: (0.01-0.03).

The strontium titanate ceramic is doped with Mg, Ho, Li and Si in specific proportions, so that the sintering temperature can be reduced, and the mechanical property and the dielectric property of the strontium titanate-based ceramic can be improved.

Preferably, the mass-to-liquid ratio of the polyimide solution is 1.5 to 2 g/mL.

Preferably, the soluble polyimide is added in an amount of 45 to 55% by mass of the strontium titanate-based ceramic powder. The use of the soluble polyimide with the dosage within the range not only ensures that the polyimide has higher mechanical property, but also ensures that the polyimide has better dielectric property and can be used in a wider working temperature area. If the using amount of the soluble polyimide is too high, the dielectric constant of the invention is obviously reduced, and the mechanical strength is reduced to a certain degree; if the amount of the soluble polyimide to be used is less than 44%, the dielectric constant of the present invention is lowered to some extent, the dielectric loss is increased, and the toughness is lowered to some extent.

Preferably, in the step-type curing process, the temperature rise program of the muffle furnace is set as follows: 120 ℃/2h, 160 ℃/1h, 200 ℃/40min, 260 ℃/30min, 320 ℃/30min, 350 ℃/10 min.

The following describes a process for preparing an electronic ceramic composite substrate with a wide working temperature range according to the present invention with reference to specific embodiments.

Example 1:

the preparation process of the electronic ceramic composite substrate of the embodiment specifically comprises the following steps:

(1) 14.8L of 45 wt% acetic acid solution and 4.9L of absolute ethyl alcohol are uniformly mixed, then 800g of tetrabutyl titanate, 220g of magnesium carbonate, 90g of holmium nitrate, 1000g of strontium hydroxide heptahydrate and 200g of lithium silicate are sequentially added while stirring, stirring is carried out for 1-2 h, then 50g of fatty alcohol-polyoxyethylene ether and 10g of triethanolamine oleate soap are added, and stirring is carried out for 30min, so as to prepare a mixed solution.

(2) And (3) placing the mixed solution into a reaction kettle, stirring and reacting for 10-15 h at 70-80 ℃, adjusting the pH value to 7-7.5 by using a 20 wt% NaOH solution, then heating to 120-140 ℃, reacting for 2-3 h, filtering, washing with deionized water for three times, and centrifuging to obtain a wet filter cake. Adding the wet filter cake into a drying oven, drying at the temperature of 110-; and then placing the mixture in a ball mill, adding a proper amount of absolute ethyl alcohol as a ball milling medium, carrying out ball milling, drying, and screening by a 800-mesh screen to obtain the strontium titanate-based ceramic powder.

(3) To 900g of the strontium titanate-based ceramic powder were added 2L of 98% concentrated sulfuric acid and 1L of 20 wt% H₂O₂Stirring the mixed liquid of water at 80-90 ℃ for reaction for 0.5-1 h, then slowly adding 1.125L of 40 wt% chitosan hydrochloride solution, continuously stirring for 6-8 h at 80-90 ℃, washing with deionized water, and centrifugally drying to obtain the modified strontium titanate-based ceramic.

(4) 202.5mL of DMF and THF were mixed at a ratio of 3: 1, then adding 405g of soluble polyimide, and stirring until the soluble polyimide is dissolved to obtain a polyimide solution.

(5) Placing the modified strontium titanate-based ceramic in a reaction kettle, adding 500mL of dimethylformamide solvent, stirring for 1h at 70-80 ℃, then slowly adding polyimide solution while stirring, stirring for reacting for 8-10 h, heating to 120-: and performing stepped curing at the temperature of 120 ℃/2h, 160 ℃/1h, 200 ℃/40min, 260 ℃/30min, 320 ℃/30min and 350 ℃/10min to prepare the electronic ceramic composite substrate.

Example 2:

the preparation process of the electronic ceramic composite substrate of the embodiment specifically comprises the following steps:

(1) uniformly mixing 12.2L of 45 wt% acetic acid solution and 3.05L of absolute ethyl alcohol, then adding 1200g of tetrabutyl titanate, 180g of magnesium carbonate, 65g of holmium nitrate, 1000g of strontium hydroxide heptahydrate and 245g of lithium silicate while stirring, stirring for 1-2 h, then adding 30g of fatty alcohol-polyoxyethylene ether and 25g of triethanolamine oleate soap, and stirring for 30min to obtain a mixed solution.

(2) And (3) placing the mixed solution into a reaction kettle, stirring and reacting for 10-15 h at 70-80 ℃, adjusting the pH value to 7-7.5 by using a 20 wt% NaOH solution, then heating to 120-140 ℃, reacting for 2-3 h, filtering, washing with deionized water for three times, and centrifuging to obtain a wet filter cake. Adding the wet filter cake into a drying oven, drying at the temperature of 110-; and then placing the mixture in a ball mill, adding a proper amount of absolute ethyl alcohol as a ball milling medium, carrying out ball milling, drying, and screening by a 800-mesh screen to obtain the strontium titanate-based ceramic powder.

(3) To 900g of the strontium titanate-based ceramic powder were added 3L of 98% concentrated sulfuric acid and 1.5L of 20 wt% H₂O₂Stirring the mixed liquid of water at 80-90 deg.C for 0.5-1 h, and slowly adding 0.9L of 60And (3) continuously stirring the chitosan hydrochloride solution with the weight percent for 6-8 h at the temperature of 80-90 ℃, washing with deionized water, and centrifugally drying to obtain the modified strontium titanate-based ceramic.

(4) 290mL of DMF and THF were mixed at 3: 1, then adding 465g of soluble polyimide, and stirring until the soluble polyimide is dissolved to obtain the polyimide solution.

(5) Placing the modified strontium titanate-based ceramic in a reaction kettle, adding 500mL of dimethylformamide solvent, stirring for 1h at 70-80 ℃, then slowly adding polyimide solution while stirring, stirring for reacting for 8-10 h, heating to 120-: and performing stepped curing at the temperature of 120 ℃/2h, 160 ℃/1h, 200 ℃/40min, 260 ℃/30min, 320 ℃/30min and 350 ℃/10min to prepare the electronic ceramic composite substrate.

Example 3:

the preparation process of the electronic ceramic composite substrate of the embodiment specifically comprises the following steps:

(1) 14.1L of 45 wt% acetic acid solution and 3.5L of absolute ethyl alcohol are uniformly mixed, then 1000g of tetrabutyl titanate, 210g of magnesium carbonate, 50g of holmium nitrate, 1000g of strontium hydroxide heptahydrate and 320g of lithium silicate are sequentially added while stirring, stirring is carried out for 1-2 h, then 45g of fatty alcohol-polyoxyethylene ether and 20g of triethanolamine oleate soap are added, and stirring is carried out for 30min, so as to prepare a mixed solution.

(2) And (3) placing the mixed solution into a reaction kettle, stirring and reacting for 10-15 h at 70-80 ℃, adjusting the pH value to 7-7.5 by using a 20 wt% NaOH solution, then heating to 120-140 ℃, reacting for 2-3 h, filtering, washing with deionized water for three times, and centrifuging to obtain a wet filter cake. Adding the wet filter cake into a drying oven, drying at the temperature of 110-; and then placing the mixture in a ball mill, adding a proper amount of absolute ethyl alcohol as a ball milling medium, carrying out ball milling, drying, and screening by a 800-mesh screen to obtain the strontium titanate-based ceramic powder.

(3) To 900g of the strontium titanate-based ceramic powder were added 2.4L of 98% concentrated sulfuric acid and 1.2L of 20 wt% H₂O₂Stirring the mixed liquid of water at 80-90 ℃ for reaction for 0.5-1 h, then slowly adding 1.1L of 50 wt% chitosan hydrochloride solution, continuously stirring for 6-8 h at 80-90 ℃, washing with deionized water, and centrifugally drying to obtain the modified strontium titanate-based ceramic.

(4) 330mL of DMF and THF were mixed in a 3: 1, then adding 495g of soluble polyimide, and stirring until the soluble polyimide is dissolved to obtain a polyimide solution.

(5) Placing the modified strontium titanate-based ceramic in a reaction kettle, adding 500mL of dimethylformamide solvent, stirring for 1h at 70-80 ℃, then slowly adding polyimide solution while stirring, stirring for reacting for 8-10 h, heating to 120-: and performing stepped curing at the temperature of 120 ℃/2h, 160 ℃/1h, 200 ℃/40min, 260 ℃/30min, 320 ℃/30min and 350 ℃/10min to prepare the electronic ceramic composite substrate.

Example 4:

the preparation process of the electronic ceramic composite substrate of the embodiment specifically comprises the following steps:

(1) uniformly mixing 11.8L of 45 wt% acetic acid solution and 3.9L of absolute ethyl alcohol, then adding 925g of tetrabutyl titanate, 165g of magnesium carbonate, 75g of holmium nitrate, 1000g of strontium hydroxide heptahydrate and 280g of lithium silicate while stirring, stirring for 1-2 h, then adding 36g of fatty alcohol-polyoxyethylene ether and 30g of triethanolamine oleate soap, and stirring for 30min to obtain a mixed solution.

(2) And (3) placing the mixed solution into a reaction kettle, stirring and reacting for 10-15 h at 70-80 ℃, adjusting the pH value to 7-7.5 by using a 20 wt% NaOH solution, then heating to 120-140 ℃, reacting for 2-3 h, filtering, washing with deionized water for three times, and centrifuging to obtain a wet filter cake. Adding the wet filter cake into a drying oven, drying at the temperature of 110-; and then placing the mixture in a ball mill, adding a proper amount of absolute ethyl alcohol as a ball milling medium, carrying out ball milling, drying, and screening by a 800-mesh screen to obtain the strontium titanate-based ceramic powder.

(3) To 900g of the strontium titanate-based ceramic powder were added 3L of 98% concentrated sulfuric acid and 1.5L of 20 wt% H₂O₂Stirring the mixed liquid of water at 80-90 ℃ for reaction for 0.5-1 h, then slowly adding 1L of 55 wt% chitosan hydrochloride solution, continuously stirring for 6-8 h at 80-90 ℃, washing with deionized water, and centrifugally drying to obtain the modified strontium titanate-based ceramic.

(4) 270mL of DMF and THF were mixed at a ratio of 3: 1, then adding 450g of soluble polyimide, and stirring until the soluble polyimide is dissolved to obtain a polyimide solution.

(5) Placing the modified strontium titanate-based ceramic in a reaction kettle, adding 500mL of dimethylformamide solvent, stirring for 1h at 70-80 ℃, then slowly adding polyimide solution while stirring, stirring for reacting for 8-10 h, heating to 120-: and performing stepped curing at the temperature of 120 ℃/2h, 160 ℃/1h, 200 ℃/40min, 260 ℃/30min, 320 ℃/30min and 350 ℃/10min to prepare the electronic ceramic composite substrate.

Comparative example 1

The preparation process of the strontium titanate ceramic substrate comprises the following steps:

(1) uniformly mixing 11.8L of 45 wt% acetic acid solution and 3.9L of anhydrous ethanol, then adding 925g of tetrabutyl titanate and 1000g of strontium hydroxide heptahydrate while stirring, stirring for 1-2 h, then adding 36g of fatty alcohol-polyoxyethylene ether and 30g of triethanolamine oleate soap, and stirring for 30min to obtain a mixed solution. And (3) placing the mixed solution into a reaction kettle, stirring and reacting for 10-15 h at 70-80 ℃, adjusting the pH value to 7-7.5 by using a 20 wt% NaOH solution, then heating to 120-140 ℃, reacting for 2-3 h, filtering, washing with deionized water for three times, and centrifuging to obtain a wet filter cake. And (3) adding the wet filter cake into a drying oven, drying at the temperature of 110-120 ℃ for 3-5 h, and then sintering at the sintering temperature of 900-1000 ℃ for 5-8 h to obtain the strontium titanate ceramic material.

(2) And uniformly mixing 100 parts of strontium titanate ceramic material, 3 parts of titanium oxide, 2 parts of aluminum oxide, 6 parts of polyvinyl alcohol and 2 parts of sodium tripolyphosphate, placing the mixture in a ball mill, adding a proper amount of absolute ethyl alcohol as a ball milling medium, carrying out ball milling, and screening the mixture through a 800-mesh screen to obtain strontium titanate slurry.

(3) Scraping the strontium titanate slurry on a casting machine by adopting a casting process to obtain a 1mm substrate biscuit, demolding the biscuit from the casting machine, drying by hot air at 200 ℃, feeding into a glue discharging furnace, discharging the glue at 650 ℃, and discharging the glue for 12 hours to obtain a biscuit sheet.

(4) And (3) feeding the blank sheet into a sintering furnace, and preserving the heat for 5-6 h at the temperature of 1200-1300 ℃ to obtain the strontium titanate ceramic substrate.

Comparative example 2

The preparation process of the strontium titanate ceramic substrate of the comparative example specifically comprises the following steps:

(1) a mixed solution was prepared, which was prepared in the same manner and in the same composition as in step (1) of example 4, with specific reference to step (1) of example 4.

(2) The preparation method of the strontium titanate-based ceramic material is the same as the step (2) of the example 4, and the specific reference is made to the example 4. Then 100 parts of strontium titanate-based ceramic material, 6 parts of polyvinyl alcohol and 2 parts of sodium tripolyphosphate are uniformly mixed, placed in a ball mill, added with a proper amount of absolute ethyl alcohol as a ball milling medium, subjected to ball milling, and sieved by a 800-mesh screen to obtain strontium titanate slurry.

(3) The green sheet was prepared in the same manner as in comparative example 1, with specific reference to comparative example 1.

(4) And (3) feeding the blank sheet into a sintering furnace, and preserving heat for 5-6 h at the temperature of 900-1000 ℃ to obtain the strontium titanate ceramic substrate.

The electronic ceramic substrates of examples 1 to 4 and comparative examples 1 to 2 were subjected to the property test, and the test results are shown in Table 1 below.

TABLE 1 mechanical property detection table for electronic ceramic substrate

According to the comparative test results in table 1, the electronic ceramic composite substrate has the advantages that the dielectric constant is 2015-2350 at 1KHz and the dielectric loss is below 0.001 at normal temperature within the temperature range of-60-250 ℃, the dielectric property of the electronic ceramic substrate is improved, the surface of the substrate is flat and smooth, the substrate has excellent quality, the production cost is saved, and the qualified rate is improved.

The technical features of the embodiments described above can 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, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present 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.