A high-strength low-temperature co-fired ceramic material and a method of making the same

Abstract

The application belongs to the technical field of low-temperature co-fired ceramic materials, and particularly relates to a high-strength low-temperature co-fired ceramic material and a preparation method thereof. The preparation method of the low-temperature co-fired ceramic material comprises the following steps: firstly, ball-milling Al2O3 powder in an ethanol medium containing KOH, then adding TEOS drop by drop and continuing to ball-mill, and then adding a small amount of CaCO3 powder to obtain modified Al2O3 heat-conducting slurry; then, ball-milling CaCO3, SiO2 and Bi2O3 raw materials uniformly, pouring the modified Al2O3 heat-conducting slurry into the ball-milled raw materials, ball-milling uniformly for a short time, drying, melting in a high-temperature furnace, water quenching, ball-milling the quenched glass melt, adding a solvent, a dispersing agent, a glue agent, a plasticizing agent and a homogenizing agent, and ball-mixing, then casting the obtained slurry into a green ceramic tape, laminating the green ceramic tape, removing glue and sintering in a high-temperature furnace to obtain an LTCC base material. The prepared low-temperature co-fired ceramic material has high strength, excellent heat conduction and low thermal expansion coefficient.

Description

Technical Field

[0001] This invention belongs to the field of low-temperature co-fired ceramic materials and their preparation, and in particular relates to an LTCC material and its preparation method. Background Technology

[0002] Low-temperature co-fired ceramic (LTCC) technology is an excellent packaging technology for achieving the integration and miniaturization of electronic components. LTCC technology can assemble circuits, inductors, electronic devices, microwave devices, etc., together to create high-density circuits that do not interfere with each other in three-dimensional space, as well as three-dimensional circuit boards with built-in passive components. It provides a good solution for the integration, miniaturization, and high reliability of electronic components, and has broad application prospects in communications, energy, aerospace, and military industries.

[0003] In the application of LTCC integrated devices, high requirements are placed on the thermal expansion coefficient and mechanical strength of LTCC materials to improve the safety and reliability of electronic components. Currently, to match the connection reliability between surface mount chips and LTCC substrate materials, the thermal expansion coefficient of various LTCC substrate materials is controlled at approximately 3.5 ppm / ℃, comparable to that of silicon-based chips. Furthermore, the strength of the LTCC substrate material is also crucial for ensuring the reliable operation of LTCC integrated devices. In some applications, to guarantee the reliability of LTCC substrate integrated devices, it is even necessary to add external high-strength protective components such as metal to ensure the safety and reliability of the internal LTCC substrate integrated devices. Therefore, improving the mechanical strength of LTCC materials is a very meaningful research direction. Al2O3 ceramic thermally conductive substrate LTCC materials are one of the mainstream LTCC materials. During low-temperature co-firing, the solubility of Al2O3 ceramic in glass is very small, which inhibits glass crystallization and affects the strength of the substrate. Insufficient wettability and bonding force between glass and Al2O3 also affect the dispersion of Al2O3 ceramic in the glass phase, inhibiting the crystallization of anorthite in the glass phase, which is detrimental to improving the strength of LTCC materials. Summary of the Invention

[0004] To address the technical problems existing in the background art, one of the objectives of this invention is to provide a high-strength low-temperature co-fired ceramic material and its preparation method. The preparation method is simple and controllable, and Al2O3 thermally conductive powder is tightly bonded to CaO-SiO2-Bi2O3 glass matrix. The obtained LTCC material has high strength, excellent thermal conductivity, low coefficient of thermal expansion, and excellent dielectric properties.

[0005] To achieve the above objectives, the present invention employs the following technical solution: a method for preparing a high-strength low-temperature co-fired ceramic material, comprising the following steps: (1) Weigh 100 parts by weight of Al2O3 powder, 100 parts by weight of ethanol and 1-5 parts by weight of KOH, mix and ball mill for 2-4 hours; then add 0.1-2 parts by weight of TEOS, ball mill for 2-4 hours, then add 1-3 parts by weight of CaCO3 powder, continue ball milling for 2-4 hours to obtain ball milled modified Al2O3 thermal conductive slurry; (2) Weigh 20-30 parts by weight of CaCO3 powder, 19-26 parts by weight of SiO2 powder, 16-24 parts by weight of Bi2O3 and 60-100 parts by weight of ethanol, mix and ball mill for 2-4 h to obtain CaCO3-SiO2-Bi2O3 mixed slurry. (3) Mix the ball-milled modified Al2O3 thermal conductive slurry from step (1) and the CaCO3-SiO2-Bi2O3 mixed slurry from step (2), ball-mill for 10-30 min, dry at 60℃, then place at 1200℃ for 2-4 h to melt, and water-cool quench to obtain quenched glass frit. (4) The quenched glass frit is ball-milled in ethanol medium for 12-20 h and dried. 150-200 parts by weight of a mixed solvent of ethanol and xylene and 3.2-4 parts by weight of dispersant are added to the powder. Then the powder is ball-milled for 8-12 h to obtain a uniformly dispersed suspension. (5) Add 8-9 parts by weight of binder, 11.4-12.85 parts by weight of plasticizer and 0.01-0.03 parts by weight of homogenizer to the suspension, and ball mill again for 8-12 h to obtain a stable and uniform slurry. The homogenizer is cyclohexane or cyclohexanone. (6) After vacuum degassing of the slurry, it is cast and dried to obtain LTCC green ceramic tape material. Then, the green ceramic tape is cut and debonded at 300-650℃ for 1-3 h, and then sintered at 750-950℃ for 1-3 h to obtain high-strength low-temperature co-fired ceramic material.

[0006] Further improvements to the preparation method of high-strength low-temperature co-fired ceramic materials: Preferably, the rotational speed of the ball mill is controlled at 200-400 r / min.

[0007] Preferably, in step (4), the amount of ethanol medium is 3-8 times the mass of the glass frit.

[0008] Preferably, in the mixed solvent of step (4), the mass ratio of ethanol to xylene is 1:(0.5-1).

[0009] Preferably, in step (4), the dispersant is one or a combination of two or more of castor oil, fish oil, phosphate ester, and triethanolamine.

[0010] Preferably, in step (5), the adhesive is one or a combination of two or more of polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, polymethyl methacrylate, and polyvinyl chloride.

[0011] Preferably, in step (5), the plasticizer is one or a combination of two or more of dibutyl phthalate, dimethyl phthalate, dioctyl phthalate, butyl benzyl phthalate, and polyethylene glycol.

[0012] Preferably, in step (5), the mass ratio of the adhesive to the plasticizer is 0.7:1.

[0013] The second objective of this invention is to provide a method for preparing high-strength low-temperature co-fired ceramic materials as described in any one of the above-mentioned methods, resulting in high-strength low-temperature co-fired ceramic materials.

[0014] The advantages of this invention compared to the prior art are as follows: 1) This invention provides a method for preparing a high-strength low-temperature co-fired ceramic material. The method involves first ball-milling Al2O3 powder in an ethanol medium containing KOH to improve the surface defects of the Al2O3 thermally conductive powder. Then, TEOS is added dropwise and ball-milling continues. A small amount of CaCO3 powder is then added and ball-milled again to obtain a modified Al2O3 thermally conductive slurry. Next, CaCO3, SiO2, and Bi2O3 raw materials are weighed and ball-milled uniformly to promote a tighter bond between the glass phase and the Al2O3 thermally conductive powder, helping Al2O3 to be better dispersed in the glass phase, effectively improving the mechanical properties of the LTCC material. The ball-milled slurry is then poured into the modified Al2O3 thermally conductive slurry, ball-milled uniformly for a short time, dried, melted in a high-temperature furnace, and water-quenched. The quenched glass melt is then ball-milled and pulverized. Solvent, dispersant, binder, plasticizer, and homogenizer are added and mixed and ball-milled. The resulting slurry is then cast into a green ceramic tape, stacked, and sintered in a high-temperature furnace to obtain the LTCC substrate.

[0015] 2) The low-temperature co-fired ceramic material obtained by this invention has a flexural strength of up to 327 MPa, a thermal conductivity greater than 3.526 W / (m·K), and a coefficient of thermal expansion of 4.28-4.56 ppm / ℃. It can be applied to packaging scenarios requiring high strength. Attached Figure Description

[0016] Figure 1 Scanning electron microscope (SEM) image of the high-strength low-temperature co-fired ceramic material prepared for this invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0018] Example 1

[0019] This embodiment provides a method for preparing a high-strength low-temperature co-fired ceramic material, including the following steps: (1) Weigh 100 parts by mass of Al2O3 powder, 100 parts by mass of ethanol and 1 part by mass of KOH, mix and ball mill for 2 h; then add 0.5 parts by mass of TEOS, ball mill for 2 h, then add 1 part by mass of CaCO3 powder, continue ball milling for 2 h to obtain ball milled modified Al2O3 thermal conductive slurry. (2) Weigh 20 parts by mass of CaCO3 powder, 26 parts by mass of SiO2 powder, 24 parts by mass of Bi2O3 and 80 parts by mass of ethanol, mix and ball mill for 2 h to obtain CaCO3-SiO2-Bi2O3 mixed slurry; (3) The Al2O3 thermally conductive slurry modified by ball milling in step (1) and the CaCO3-SiO2-Bi2O3 mixed slurry in step (2) are mixed, ball milled for 10 min, dried by blowing at 60°C, and then placed at 1200°C for 2 h to melt. After water cooling and quenching, quenched glass frit is obtained. (4) The quenched glass frit was ball-milled in 3 parts by mass of ethanol medium for 12 h and dried. 180 parts by mass of mixed solvent (mixed solvent of ethanol and xylene in a mass ratio of 1:1) and 3.6 parts by mass of dispersant (castor oil) were added to the powder. Then the powder was ball-milled for 8 h to obtain a uniformly dispersed suspension. (5) Add 9 parts by weight of binder (polyvinyl butyral), 12.85 parts by weight of plasticizer (butyl benzyl phthalate) and 0.02 parts by weight of homogenizer (cyclohexanone) to the suspension, and ball mill again for 8 h to obtain a stable and uniform slurry. (6) After vacuum degassing of the slurry, it is cast and dried to obtain LTCC green ceramic tape material. Then, the green ceramic tape is cut and debonded at 300℃ for 3 h, and then sintered at 800℃ for 2 h to obtain high-strength low-temperature co-fired ceramic material.

[0020] Example 2

[0021] This embodiment provides a method for preparing a high-strength low-temperature co-fired ceramic material, including the following steps: (1) Weigh 100 parts by mass of Al2O3 powder, 100 parts by mass of ethanol and 2 parts by mass of KOH, mix and ball mill for 2 h; then add 2 parts by mass of TEOS, ball mill for 2 h, then add 3 parts by mass of CaCO3 powder, continue ball milling for 2 h, and obtain ball milled modified Al2O3 thermal conductive slurry. (2) Weigh 21 parts by mass of CaCO3 powder, 19 parts by mass of SiO2 powder, 20 parts by mass of Bi2O3 and 60 parts by mass of ethanol, mix and ball mill for 2 h to obtain CaCO3-SiO2-Bi2O3 mixed slurry; (3) The Al2O3 thermally conductive slurry modified by ball milling in step (1) and the CaCO3-SiO2-Bi2O3 mixed slurry in step (2) are mixed, ball milled for 20 min, dried by blowing at 60℃, and then placed at 1200℃ for 2 h to melt. After water cooling and quenching, quenched glass frit is obtained. (4) The quenched glass frit was ball-milled in 5 parts by mass of ethanol medium for 12 h and dried. 163 parts by mass of mixed solvent (mixed solvent of ethanol and xylene in a mass ratio of 1:1) and 3.2 parts by mass of dispersant (castor oil) were added to the powder. Then the powder was ball-milled for 8 h to obtain a uniformly dispersed suspension. (5) Add 8 parts by weight of binder (polyvinyl butyral), 11.4 parts by weight of plasticizer (butyl benzyl phthalate) and 0.02 parts by weight of homogenizer (cyclohexanone) to the suspension, and ball mill again for 8 h to obtain a stable and uniform slurry. (6) After vacuum degassing of the slurry, it is cast and dried to obtain LTCC green ceramic tape material. Then, the green ceramic tape is cut and debonded at 650℃ for 1 h, and then sintered at 900℃ for 2 h to obtain high-strength low-temperature co-fired ceramic material.

[0022] Example 3

[0023] This embodiment provides a method for preparing a high-strength low-temperature co-fired ceramic material, including the following steps: (1) Weigh 100 parts by mass of Al2O3 powder, 100 parts by mass of ethanol and 5 parts by mass of KOH, mix and ball mill for 4 h; then add 1 part by mass of TEOS, ball mill for 4 h, then add 2 parts by mass of CaCO3 powder, continue ball milling for 4 h to obtain ball milled modified Al2O3 thermal conductive slurry. (2) Weigh 30 parts by weight of CaCO3 powder, 22 parts by weight of SiO2 powder, 20 parts by weight of Bi2O3 and 70 parts by weight of ethanol, mix and ball mill for 4 h to obtain CaCO3-SiO2-Bi2O3 mixed slurry; (3) The Al2O3 thermally conductive slurry modified by ball milling in step (1) and the CaCO3-SiO2-Bi2O3 mixed slurry in step (2) are mixed, ball milled for 20 min, dried by blowing at 60℃, and then placed at 1200℃ for 2 h to melt. After water cooling and quenching, quenched glass frit is obtained. (4) The quenched glass frit was ball-milled in 5 parts by mass of ethanol medium for 12 h and dried. 170 parts by mass of mixed solvent (mixed solvent of ethanol and xylene in a mass ratio of 1:0.5) and 3.4 parts by mass of dispersant (castor oil) were added to the powder. Then the powder was ball-milled for 8 h to obtain a uniformly dispersed suspension. (5) Add 8.5 parts by weight of binder (polyvinyl butyral), 12.1 parts by weight of plasticizer (butyl benzyl phthalate) and 0.03 parts by weight of homogenizer (cyclohexanone) to the suspension, and ball mill again for 8 h to obtain a stable and uniform slurry. (6) After vacuum degassing of the slurry, it is cast and dried to obtain LTCC green ceramic tape material. Then, the green ceramic tape is cut and debonded at 600℃ for 2 h, and then sintered at 850℃ for 2 h to obtain high-strength low-temperature co-fired ceramic material.

[0024] Example 4

[0025] This embodiment provides a method for preparing a high-strength low-temperature co-fired ceramic material, including the following steps: (1) Weigh 100 parts by mass of Al2O3 powder, 100 parts by mass of ethanol and 2 parts by mass of KOH, mix and ball mill for 2 h; then add 1 part by mass of TEOS, ball mill for 2 h, then add 1 part by mass of CaCO3 powder, continue ball milling for 2 h, and obtain ball milled modified Al2O3 thermal conductive slurry. (2) Weigh 27 parts by mass of CaCO3 powder, 23 parts by mass of SiO2 powder, 16 parts by mass of Bi2O3 and 70 parts by mass of ethanol, mix and ball mill for 2 h to obtain CaCO3-SiO2-Bi2O3 mixed slurry; (3) The Al2O3 thermally conductive slurry modified by ball milling in step (1) and the CaCO3-SiO2-Bi2O3 mixed slurry in step (2) are mixed, ball milled for 30 min, dried by blowing at 60℃, and then placed at 1200℃ for 2 h to melt. After water cooling and quenching, quenched glass frit is obtained. (4) The quenched glass frit was ball-milled in 3 parts by mass of ethanol medium for 20 h and dried. 170 parts by mass of mixed solvent (mixed solvent of ethanol and xylene in a mass ratio of 1:1) and 3.4 parts by mass of dispersant (castor oil) were added to the powder. Then the powder was ball-milled for 8 h to obtain a uniformly dispersed suspension. (5) Add 8.5 parts by weight of binder (polyvinyl butyral), 12.1 parts by weight of plasticizer (butyl benzyl phthalate) and 0.03 parts by weight of homogenizer (cyclohexanone) to the suspension, and ball mill again for 8 h to obtain a stable and uniform slurry. (6) After vacuum degassing of the slurry, it is cast and dried to obtain LTCC green ceramic tape material. Then, the green ceramic tape is cut and debonded at 600℃ for 2 h, and then sintered at 900℃ for 1 h to obtain high-strength low-temperature co-fired ceramic material.

[0026] Example 5

[0027] This embodiment provides a method for preparing a high-strength low-temperature co-fired ceramic material, including the following steps: (1) Weigh 100 parts by mass of Al2O3 powder, 100 parts by mass of ethanol and 1 part by mass of KOH, mix and ball mill for 2 h; then add 1 part by mass of TEOS, ball mill for 2 h, then add 1 part by mass of CaCO3 powder, continue ball milling for 2 h, and obtain ball milled modified Al2O3 thermal conductive slurry. (2) Weigh 30 parts by weight of CaCO3 powder, 26 parts by weight of SiO2 powder, 24 parts by weight of Bi2O3 and 100 parts by weight of ethanol, mix and ball mill for 2 h to obtain CaCO3-SiO2-Bi2O3 mixed slurry; (3) The Al2O3 thermally conductive slurry modified by ball milling in step (1) and the CaCO3-SiO2-Bi2O3 mixed slurry in step (2) are mixed, ball milled for 10 min, dried by blowing at 60°C, and then placed at 1200°C for 2 h to melt. After water cooling and quenching, quenched glass frit is obtained. (4) The quenched glass frit was ball-milled in 3 parts by mass of ethanol medium for 12 h and dried. 180 parts by mass of mixed solvent (mixed solvent of ethanol and xylene in a mass ratio of 1:1) and 3.6 parts by mass of dispersant (castor oil) were added to the powder. Then the powder was ball-milled for 8 h to obtain a uniformly dispersed suspension. (5) Add 9 parts by weight of binder (polyvinyl butyral), 12.85 parts by weight of plasticizer (butyl benzyl phthalate) and 0.02 parts by weight of homogenizer (cyclohexanone) to the suspension, and ball mill again for 8 h to obtain a stable and uniform slurry. (6) After vacuum degassing of the slurry, it is cast and dried to obtain LTCC green ceramic tape material. Then, the green ceramic tape is cut and debonded at 620℃ for 2 h, and then sintered at 800℃ for 1.5 h to obtain high-strength low-temperature co-fired ceramic material.

[0028] Figure 1 These are scanning electron microscope (SEM) images of the high-strength, low-temperature co-fired ceramic material prepared in Example 1; [The image is from...] Figure 1It is known that the surface of alumina contains nanoparticles with a size of about 10-50 nm. The alumina is encapsulated by a glass phase, and the glass phase and the alumina ceramic phase are in close contact.

[0029] The test results of thermal conductivity, coefficient of thermal expansion, and flexural strength of the high-strength low-temperature co-fired ceramic materials prepared in Examples 1-5 are shown in Table 1 below: Table 1

[0030] The test results show that after ball milling Al2O3 powder in an alkaline solution, combining it with in-situ riveted silica nanoparticles, and adding a small amount of calcium carbonate nanoparticles for further ball milling, a modified Al2O3 thermally conductive slurry is obtained. This slurry is then ball-milled and mixed with a CaCO3-SiO2-Bi2O3 glass powder raw material, sintered, and then ball-milled into co-fired ceramic powder. Adding a casting aid yields a green ceramic tape. The sintered ceramic sample exhibits significantly improved flexural strength, reaching a maximum of 327 MPa, while maintaining a thermal conductivity above 3.526 W / (m·K) and a coefficient of thermal expansion of 4.28-4.56 ppm / ℃. This high flexural strength broadens the encapsulation applications of this low-temperature co-fired ceramic material in applications requiring high strength.

[0031] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength low-temperature co-fired ceramic material, characterized in that, Includes the following steps: (1) Weigh 100 parts by weight of Al2O3 powder, 100 parts by weight of ethanol and 1-5 parts by weight of KOH, mix and ball mill for 2-4 h; then add 0.1-2 parts by weight of TEOS, ball mill for 2-4 h, then add 1-3 parts by weight of CaCO3 powder, continue ball milling for 2-4 h to obtain ball milled modified Al2O3 thermal conductive slurry; (2) Weigh 20-30 parts by weight of CaCO3 powder, 19-26 parts by weight of SiO2 powder, 16-24 parts by weight of Bi2O3 and 60-100 parts by weight of ethanol, mix and ball mill for 2-4 h to obtain CaCO3-SiO2-Bi2O3 mixed slurry. (3) Mix the ball-milled modified Al2O3 thermal conductive slurry from step (1) and the CaCO3-SiO2-Bi2O3 mixed slurry from step (2), ball-mill for 10-30 min, dry at 60℃, then place at 1200℃ for 2-4 h to melt, and water-cool quench to obtain quenched glass frit. (4) The quenched glass frit is ball-milled in ethanol medium for 12-20 h and dried. 150-200 parts by weight of a mixed solvent of ethanol and xylene and 3.2-4 parts by weight of dispersant are added to the powder. Then the powder is ball-milled for 8-12 h to obtain a uniformly dispersed suspension. (5) Add 8-9 parts by weight of binder, 11.4-12.85 parts by weight of plasticizer and 0.01-0.03 parts by weight of homogenizer to the suspension, and ball mill again for 8-12 h to obtain a stable and uniform slurry. The homogenizer is cyclohexane or cyclohexanone. (6) After vacuum degassing of the slurry, it is cast and dried to obtain LTCC green ceramic tape material. Then, the green ceramic tape is cut and debonded at 300-650℃ for 1-3 h, and then sintered at 750-950℃ for 1-3 h to obtain high-strength low-temperature co-fired ceramic material.

2. The method for preparing a high-strength low-temperature co-fired ceramic material according to claim 1, characterized in that, The rotational speed of the ball mill is controlled at 200-400 r / min.

3. The method for preparing a high-strength low-temperature co-fired ceramic material according to claim 1, characterized in that, In step (4), the amount of ethanol medium is 3-8 times the mass of the glass frit.

4. The method for preparing a high-strength low-temperature co-fired ceramic material according to claim 1, characterized in that, In the mixed solvent of step (4), the mass ratio of ethanol to xylene is 1:(0.5-1).

5. The method for preparing a high-strength low-temperature co-fired ceramic material according to claim 1, characterized in that, In step (4), the dispersant is one or a combination of two or more of castor oil, fish oil, phosphate ester, and triethanolamine.

6. The method for preparing a high-strength low-temperature co-fired ceramic material according to claim 1, characterized in that, In step (5), the adhesive is one or a combination of two or more of polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, polymethyl methacrylate, and polyvinyl chloride.

7. The method for preparing a high-strength low-temperature co-fired ceramic material according to claim 1, characterized in that, In step (5), the plasticizer is one or a combination of two or more of dibutyl phthalate, dimethyl phthalate, dioctyl phthalate, butyl benzyl phthalate, and polyethylene glycol.

8. A method for preparing a high-strength low-temperature co-fired ceramic material according to claim 1 or 7, characterized in that, In step (5), the mass ratio of the adhesive to the plasticizer is 0.7:

1.

9. A high-strength low-temperature co-fired ceramic material prepared by the method of any one of claims 1-8.

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