Preparation method of low-temperature co-fired ceramic high-density green ceramic chip

Abstract

The invention belongs to the technical field of low-temperature co-fired ceramics, and particularly relates to a preparation method of a low-temperature co-fired ceramic high-density green ceramic chip. The preparation method comprises the following steps: glass powder modification, ceramic powder modification, primary ball milling, secondary ball milling and tape casting. According to the technical scheme provided by the invention, two ionic or organic substances which can attract or combine with each other are adopted to modify the surfaces of the glass powder and the ceramic powder respectively, so that the problem of sedimentation after primary ball milling is avoided; the two kinds of inorganic powder are subjected to ball milling, mixing and dispersing, and the distance between the two kinds of powder in the slurry is shortened through the interaction between ions or groups on the surfaces of the powder, so that the affinity between the powder is improved, and the compactness of the green ceramic chip is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-temperature co-fired ceramics, and particularly relates to a method for preparing a high-density green ceramic sheet of low-temperature co-fired ceramics. Background Art

[0002] With the rapid development of electronic information technology, electronic products and communication devices are developing towards miniaturization and lightweight. Therefore, higher requirements are put forward for the performance of electronic components, namely componentization, high integration, etc. Low Temperature Cofired Ceramic (LTCC) technology has become a widely used process technology route for electronic ceramic components and high-density integrated circuits due to its advantages such as high integration, high frequency, and high transmission rate, and is widely used in the fields of aerospace, military, communication, and large computers.

[0003] Currently, the mainstream LTCC systems are mainly the glass-ceramic system and the glass / ceramic system. The glass / ceramic system has the advantages of high strength and easy performance regulation compared with the glass-ceramic system. However, at the same time, the addition of ceramic powder makes the poor affinity between the two powders one of the main factors affecting the density of ceramics. In the conventional slurry preparation process, ceramic and glass powders need to be put into an organic solvent and a dispersant, and mixed and dispersed through long-term ball milling. Although a dispersant is added, there are still phenomena of uneven mixing of ceramic and glass powders and easy sedimentation of inorganic powders in the ceramic slurry system after one-time ball milling, which will affect the uniformity and density of the cast green ceramic sheet, resulting in problems such as insufficient strength of the sintered ceramic substrate.

[0004] Chinese Patent CN115385666A provides a high-thermal-conductivity low-temperature co-fired ceramic material and its preparation method, which selects ZBNAS glass with trace crystallization as the glass phase and silicon carbide nanowires and alumina as the composite ceramic phase. The glass powder has a particle size of about 400 nm, a large specific surface area, a high surface activation energy, and good wetting performance, and can better wet the ceramic powder after melting at high temperature, improving the density of LTCC. However, the raw materials used are difficult to obtain and are not suitable for industrial use. Summary of the Invention

[0005] The present invention provides a method for preparing a high-density green ceramic sheet of low-temperature co-fired ceramics to solve the problem of poor density in the current LTCC system.

[0006] To solve the above technical problems, the technical solution of the present invention is: The method for preparing a high-density green ceramic sheet of low-temperature co-fired ceramics includes the following steps:

[0007] S1 Glass powder modification: The glass powder is dispersed in a solvent. After ultrasonic treatment, sodium stearate is added, and then the pH value is adjusted to 8 - 10. After washing, drying, and screening, the modified glass powder is obtained;

[0008] S2 Ceramic powder modification: The alumina ceramic powder is dispersed in a solvent. After ultrasonic treatment, lanthanum trifluoromethanesulfonate is added, and then the pH value is adjusted to 8 - 10. After washing, drying, and screening, the modified ceramic powder is obtained;

[0009] S3 First ball milling: Weigh the modified glass powder obtained in step S1 and the modified ceramic powder obtained in step S2, and then add a solvent and a dispersant for first ball milling;

[0010] S4 Second ball milling: Add a binder and a plasticizer to the slurry obtained in step S3 for second ball milling to obtain a stable and uniform slurry;

[0011] S5 Tape casting: Tape cast the slurry obtained in step S4 to obtain the high - density green ceramic sheet for low - temperature co - firing ceramics.

[0012] Sodium stearate forms hydrogen bonds or van der Waals forces with the hydroxyl groups (-OH) on the surface of the glass powder through its hydrophobic groups, adsorbs on the particle surface, and forms a monolayer or multi - layer coating structure.

[0013] And there are usually hydroxyl groups (-OH) on the surface of alumina. In an alkaline environment, these hydroxyl groups are deprotonated to form oxygen anions (O 2- ) providing electron pairs. And the fluorine atoms in lanthanum trifluoromethanesulfonate have a high electronegativity, which reduces the electron cloud density around the sulfur atom, making it easier to accept electrons, and thus easier to combine with alumina and coat on the surface of alumina.

[0014] After modification, the Lewis acid on the surface of alumina accepts the electron pairs from the Lewis base on the surface of the glass powder for combination, reducing the distance between the glass powder and the ceramic powder, and can effectively improve the density of the green ceramic sheet.

[0015] Optionally, the composition of the glass powder in step S1 is 29 wt% CaO, 32 wt% B2O3, and 39 wt% SiO2.

[0016] Optionally, acetic acid is used as the pH regulator in step S1, and sodium hydroxide is used as the pH regulator in step S2.

[0017] Optionally, the solvents in both step S1 and step S2 are a mixture of anhydrous ethanol and deionized water with a mass ratio of 1:1.

[0018] Optionally, the ultrasonic treatment duration in step S1 is 2 h, and the ultrasonic treatment duration in step S2 is 1 h.

[0019] Optionally, the proportions of the substances used in step S1 by weight are as follows:

[0020] Glass powder: 100 parts

[0021] Solvent: 180 - 220 parts

[0022] Sodium stearate: 0.8 - 1.2 parts.

[0023] Optionally, the proportions of the substances used in step S2 by weight are as follows:

[0024] Glass powder: 100 parts

[0025] Solvent: 180 - 220 parts

[0026] Lanthanum trifluoromethanesulfonate: 0.8 - 1.2 parts.

[0027] Optionally, in step S3, the solvent is a mixed solution of ethyl acetate and isopropyl alcohol, the dispersant is castor oil, in step S4, the binder is PVB (polyvinyl butyral), and the plasticizer is dibutyl phthalate.

[0028] Optionally, the weight ratio of ethyl acetate to isopropyl alcohol in the solvent of step S3 is 2:1.

[0029] Optionally, the weight ratio of the modified glass powder to the modified ceramic powder in step S3 is 10:(6.8 - 7.2).

[0030] Optionally, the duration of the first ball milling is 12 - 24 h, and the duration of the second ball milling is 12 - 24 h.

[0031] The technical solution provided by the present invention uses two ionic or organic substances that can attract or combine with each other to modify the surfaces of glass and ceramic powders respectively, avoiding the problem of sedimentation after the first ball milling; then the two inorganic powders are ball milled and mixed and dispersed, and the interaction between ions or groups on the powder surfaces shortens the distance between the two powders in the slurry, that is, improves the affinity between the powders, thereby improving the densification of the green ceramic chips. Detailed Embodiments

[0032] For ease of understanding, the preparation method of the low - temperature co - fired ceramic high - density green ceramic chips is described below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0033] Example 1

[0034] S1 Weigh 100 g of glass powder (29 wt% CaO - 32 wt% B2O3 - 39 wt% SiO2) and mix it in a mixed solvent of 200 g of absolute ethanol and deionized water (the mass ratio of absolute ethanol to deionized water is 1:1). Ultrasonically treat for 2 h, then add 1 g of sodium stearate thereto, adjust the pH to about 9 with acetic acid and magnetically stir for 4 h. Then, after ultrasonic cleaning three times, the successfully modified glass powder is obtained through drying and sieving.

[0035] S2 Weigh 100 g of ceramic powder (Al2O3) and mix it in a mixed solvent of 200 g of absolute ethanol and deionized water (the mass ratio of absolute ethanol to deionized water is 1:1). Ultrasonically treat for 1 h, then add 1 g of lanthanum trifluoromethanesulfonate thereto, adjust the pH to about 10 with sodium hydroxide and magnetically stir for 2 h. Then, after ultrasonic cleaning three times, the successfully modified alumina ceramic powder is obtained through drying and sieving.

[0036] S3 Weigh 50 g of modified glass powder and 35 g of modified alumina ceramic powder, add them to a mixed solution of 59.5 g of ethyl acetate and isopropanol (mass ratio of ethyl acetate:isopropanol = 2:1), and then add 0.85 g of dispersant castor oil and perform ball milling for about 15 h for the first time.

[0037] S4 Add 9.6 g of binder PVB and 3.84 g of plasticizer dibutyl phthalate to the slurry after the first ball milling, and perform ball milling for about 15 h for the second time to obtain a stable and uniform slurry.

[0038] S5 Cast the obtained slurry to form a high-density LTCC green ceramic sheet with a density of 1.86 g / cm 3 。

[0039] Example 2

[0040] S1 Weigh 100 g of glass powder (29 wt% CaO - 32 wt% B2O3 - 39 wt% SiO2) and mix it in a mixed solvent of 220 g of absolute ethanol and deionized water (the mass ratio of absolute ethanol to deionized water is 1:1). Ultrasonically treat for 2 h, then add 0.8 g of sodium stearate thereto, adjust the pH to about 9 with acetic acid and magnetically stir for 4 h. Then, after ultrasonic cleaning three times, the successfully modified glass powder is obtained through drying and sieving.

[0041] S2 Weigh 100 g of ceramic powder (Al2O3) and mix it in a mixed solvent of 190 g of absolute ethanol and deionized water (the mass ratio of absolute ethanol to deionized water is 1:1). Ultrasonically treat for 1 h, then add 1 g of lanthanum trifluoromethanesulfonate thereto, adjust the pH to about 9 with sodium hydroxide and magnetically stir for 2 h. Then, after ultrasonic cleaning three times, the successfully modified alumina ceramic powder is obtained through drying and sieving.

[0042] S3 Weigh 50 g of modified glass powder and 35 g of modified alumina ceramic powder, add them to a mixed solution of 59.5 g of ethyl acetate and isopropanol (mass ratio of ethyl acetate: isopropanol = 2:1), and then add 0.85 g of dispersant castor oil for primary ball milling and mixing for about 12 h.

[0043] S4 Add 9.6 g of binder PVB and 3.84 g of plasticizer dibutyl phthalate to the slurry after primary ball milling, and conduct secondary ball milling for about 20 h to obtain a stable and uniform slurry.

[0044] S5 Cast the obtained slurry to form a high-density LTCC green ceramic sheet.

[0045] Example 3

[0046] S1 Weigh 100 g of glass powder (29 wt% CaO - 32 wt% B2O3 - 39 wt% SiO2) and mix it in a mixed solvent of 180 g of absolute ethanol and deionized water (mass ratio of absolute ethanol to deionized water is 1:1), ultrasonically treat for 2 h, then add 1.1 g of sodium stearate to it, adjust the pH to about 10 with acetic acid and magnetically stir for 4 h, and then ultrasonically clean 3 times and then obtain the successfully modified glass powder after drying and sieving.

[0047] S2 Weigh 100 g of ceramic powder (Al2O3) and mix it in a mixed solvent of 210 g of absolute ethanol and deionized water (mass ratio of absolute ethanol to deionized water is 1:1), ultrasonically treat for 1 h, then add 0.8 g of lanthanum trifluoromethanesulfonate to it, adjust the pH to about 8 with sodium hydroxide and magnetically stir for 2 h, and then ultrasonically clean 3 times and then obtain the successfully modified alumina ceramic powder after drying and sieving.

[0048] S3 Weigh 50 g of modified glass powder and 35 g of modified alumina ceramic powder, add them to a mixed solution of 59.5 g of ethyl acetate and isopropanol (mass ratio of ethyl acetate: isopropanol = 2:1), and then add 0.85 g of dispersant castor oil for primary ball milling and mixing for about 20 h.

[0049] S4 Add 9.6 g of binder PVB and 3.84 g of plasticizer dibutyl phthalate to the slurry after primary ball milling, and conduct secondary ball milling for about 24 h to obtain a stable and uniform slurry.

[0050] S5 Cast the obtained slurry to form a high-density LTCC green ceramic sheet.

[0051] Comparative Example 1

[0052] The difference from Example 1 is that the alumina ceramic powder was not modified in step S2, and the density of the green ceramic sheet obtained after casting is 1.73 g / cm 3 .

[0053] Comparative Example 2

[0054] The difference from Example 1 is that the glass powder was not modified in step S1, and the density of the green ceramic sheet obtained after casting was 1.75 g / cm 3 .

[0055] Comparative Example 3

[0056] The difference from Example 1 is that neither the glass powder nor the alumina ceramic powder was modified. That is, starting directly from step S3, the density of the green ceramic sheet obtained by casting was 1.69 g / cm 3 .

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a low-temperature co-fired ceramic high-density green ceramic chip, characterized in that It includes the following steps: S1 Modification of glass powder: The glass powder is dispersed in a solvent. After ultrasonic treatment, sodium stearate is added, and then the pH value is adjusted to 8 - 10 for cleaning. After drying and screening, the modified glass powder is obtained; S2 Modification of ceramic powder: The alumina ceramic powder is dispersed in a solvent. After ultrasonic treatment, lanthanum trifluoromethanesulfonate is added, and then the pH value is adjusted to 8 - 10, followed by cleaning, drying and screening to obtain the modified ceramic powder; S3 Primary ball milling: Weigh the modified glass powder obtained in step S1 and the modified ceramic powder obtained in step S2, and then add a solvent and a dispersant for primary ball milling; S4 Secondary ball milling: Add a binder and a plasticizer to the slurry obtained in step S3 for secondary ball milling to obtain a stable and uniform slurry; S5 Tape casting: Tape cast the slurry obtained in step S4 to obtain the low-temperature co-fired ceramic high-density green ceramic sheet.

2. The preparation method of the low-temperature co-fired ceramic high-density green ceramic sheet according to claim 1, characterized in that, In step S1, the composition of the glass powder is 29 wt% CaO, 32 wt% B2O3 and 39 wt% SiO2.

3. The preparation method of the low-temperature co-fired ceramic high-density green ceramic chip according to claim 1, characterized in that, In step S1, acetic acid is used as the pH regulator, and in step S2, sodium hydroxide is used as the pH regulator.

4. The preparation method of the low-temperature co-fired ceramic high-density green ceramic sheet according to claim 1, characterized in that The solvents in steps S1 and S2 are both mixtures of absolute ethanol and deionized water with a mass ratio of 1:

1.

5. The preparation method of the low-temperature co-fired ceramic high-density green ceramic sheet according to claim 1, characterized in that, The proportions of the substances used in step S1 by weight are as follows: Glass powder 100 parts Solvent 180 - 220 parts Sodium stearate 0.8 - 1.2 parts.

6. The preparation method of the low-temperature co-fired ceramic high-density green ceramic sheet according to claim 1, characterized in that, The proportions of the substances used in step S2 by weight are as follows: Glass powder 100 parts Solvent 180 - 220 parts Lanthanum trifluoromethanesulfonate 0.8 - 1.2 parts.

7. The preparation method of the low-temperature co-fired ceramic high-density green ceramic sheet according to claim 1, characterized in that, In step S3, the solvent is a mixed solution of ethyl acetate and isopropyl alcohol, the dispersant is castor oil, the binder in step S4 is PVB, and the plasticizer is dibutyl phthalate.

8. The preparation method of the low-temperature co-fired ceramic high-density green ceramic sheet according to claim 7, characterized in that The weight ratio of ethyl acetate and isopropyl alcohol, the solvents in step S3, is 2:

1.

9. The preparation method of the low-temperature co-fired ceramic high-density green ceramic sheet according to claim 1, characterized in that, The weight ratio of the modified glass powder and the modified ceramic powder in step S3 is 10:(6.8 - 7.2).

10. The preparation method of the low-temperature co-fired ceramic high-density green ceramic sheet according to claim 1, wherein The ultrasonic treatment duration in step S1 is 2 h, and the ultrasonic treatment duration in step S2 is 1 h.