Preparation method of multilayer ceramic substrate with excellent interlayer bonding property

Abstract

The invention discloses a preparation method of a multilayer ceramic substrate with excellent interlayer bonding performance. The preparation method comprises the following steps: mixing alumina powder, chromic oxide powder and yttrium oxide powder, and carrying out ball milling and sieving; uniformly mixing and stirring the binder, the plasticizer, the dispersing agent and the solvent; mixing the mixed powder and the organic mixed slurry, and carrying out vacuum defoaming; the slurry is subjected to tape casting preforming, and then a green body obtained after tape casting preforming is subjected to drying oven preheating and then laminated dry pressing forming; and carrying out pressureless sintering on the multi-layer ceramic substrate green body through a specific glue discharging and sintering integrated system to obtain the multi-layer ceramic substrate with excellent interlayer bonding property. By adopting the preparation method of the multi-layer ceramic substrate with excellent interlayer bonding property, good interlayer bonding and densification of the multi-layer aluminum oxide ceramic substrate can be realized under a non-pressure condition, and the problems of long period, low efficiency, high energy consumption and expensive and vulnerable hot-pressing molds in high-temperature hot-pressing of a traditional high-temperature hot-pressing sintering process are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic electronic packaging, and in particular relates to a method for preparing a multilayer ceramic substrate with excellent interlayer bonding. Background Art

[0002] Ceramic packaging substrate is a revolutionary technology in the field of electronic packaging. Due to its excellent insulation, low dielectric constant, low thermal expansion coefficient, high thermal conductivity and excellent airtightness, it has shown great advantages in performance improvement, technological innovation, packaging process improvement, cost-effectiveness optimization, environmental protection and energy saving, bringing new solutions and development directions to the field of electronic packaging. Interlayer bonding is one of the most critical properties in the production of ceramic packaging substrates. It is a key factor affecting the quality, performance and service life of ceramic packaging substrates, and ultimately determines whether ceramic packaging substrates can be used in industrial production on a large scale. The research on interlayer bonding technology plays an important role in promoting the process of multilayer ceramic packaging substrates. By optimizing the sintering process and selecting suitable materials, the bonding strength between the metal conductive layer and the ceramic substrate can be greatly improved, thereby improving the reliability and performance of the entire packaging substrate. Therefore, interlayer bonding technology is an indispensable part of the development of multilayer ceramic packaging substrate technology.

[0003] Multilayer ceramic packaging substrate is an electronic packaging technology with the best comprehensive performance and the most development prospects in the current electronic packaging field. It has been vigorously researched and developed by industrial powers around the world. The key to the research of multilayer ceramic packaging substrates is to improve the bonding between ceramic substrate layers. Multilayer ceramic packaging substrate materials are required to have good insulation, heat resistance, high thermal conductivity and excellent airtightness. At the same time, they are required to have good bonding between different layers, so as to achieve good vertical interconnection and improve integration. The process of pressureless sintering of ceramic packaging substrates after lamination dry pressing can prepare a multilayer structure with good interlayer bonding at a low cost, while meeting the airtight packaging requirements of electronic devices. Therefore, the study of the bonding between ceramic substrate layers plays an important role in promoting the application of multilayer ceramic packaging substrates.

[0004] The multilayer alumina ceramic packaging substrate is mainly composed of α-Al2O3, Cr2O3 and Y2O3 as sintering aids and exist in the substrate as secondary phases. It has high strength, good insulation, low dielectric constant, good heat resistance and other properties, and is widely used as an electronic packaging substrate. At present, the interlayer bonding of multilayer alumina ceramic substrates mainly depends on high-temperature hot pressing sintering, which has a long high-temperature hot pressing cycle, low efficiency, high energy consumption, and the hot pressing mold is expensive and fragile.

[0005] Therefore, the art needs to develop a method for preparing a multilayer ceramic substrate with excellent interlayer bonding, and needs to explore a new pressureless debinding sintering integration system for preparing a ceramic substrate with good interlayer bonding, which can effectively solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a multilayer ceramic substrate with excellent interlayer bonding, which can achieve good interlayer bonding and densification of the multilayer alumina ceramic substrate under pressureless conditions, and solve the problems of long cycle, low efficiency, high energy consumption and expensive and fragile hot pressing molds in traditional high-temperature hot pressing sintering processes.

[0007] To achieve the above object, the present invention provides a method for preparing a multilayer ceramic substrate with excellent interlayer bonding, comprising the following steps: Step S1, mixing aluminum oxide powder, chromium oxide powder and yttrium oxide powder, ball-milling the mixture, and then sieving the mixture to obtain a mixed powder; Step S2, mixing and stirring the binder, plasticizer, dispersant and solvent to obtain an organic mixed slurry; Step S3, mixing the mixed powder and the organic mixed slurry, stirring evenly, and then vacuum degassing to obtain a slurry; Step S4, performing tape casting preforming on the slurry, and then preheating the tape casting preformed green body in an oven and then laminating and dry pressing the green body to obtain a multi-layer ceramic substrate green body; Step S5: pressurelessly sintering the green body of the multilayer ceramic substrate by a specific debinding and sintering integration system, thereby obtaining a multilayer ceramic substrate with excellent interlayer bonding.

[0008] Preferably, in step S1, the aluminum oxide powder, the chromium oxide powder and the yttrium oxide powder are all micro-nano-scale; the mass ratio of the aluminum oxide powder, the chromium oxide powder and the yttrium oxide powder is 80-90:5-15:5-10.

[0009] Preferably, during ball milling, the ball-to-material ratio is 0.5:1-2:1, the rotation speed is 100-300 r / min, the mixing time is 240-360 min, and the sieve is 60-80 mesh.

[0010] Preferably, in step S2, the binder, plasticizer, dispersant and solvent are polyvinyl alcohol, polyethylene glycol, ethyl acetate and ethanol respectively; and the mass ratio thereof is 10-30:10-30:30-50:50-70.

[0011] Preferably, in step S3, the added mass of the organic mixed slurry is 25-50% of the mass of the mixed powder; Among them, the vacuum defoaming time is 30~60min.

[0012] Preferably, in step S4, the preheating temperature is 80-110° C.; the lamination dry pressing pressure is 80-120 MPa, and the holding time is 5-20 min.

[0013] Preferably, in step S5, the specific debinding and sintering integration system is as follows: when the temperature is less than or equal to 180°C, the heating rate is set to 1~3°C / min, and the temperature is kept at 150~200°C for 10~90min; when the temperature is greater than 180°C and less than 285°C, the heating rate is set to 1~3°C / min, and the temperature is kept at 200~300°C for 10~90min; when the temperature is greater than 285°C and less than 500°C, the heating rate is set to 1~3°C / min, and the temperature is kept at 500°C for 90~150min; when the temperature is greater than 500°C and less than 700°C, the heating rate is set to 1~3°C / min; when the temperature is greater than 700°C and less than 1300°C, the heating rate is adjusted to 3~15°C / min, the temperature is raised to 1300~1800°C, and the temperature is kept for 200~420min.

[0014] Preferably, in step S5, the multilayer ceramic substrate green body is placed in a self-made substrate warping prevention device for pressureless sintering; The structure of the homemade anti-substrate warping device is, from top to bottom, a large-radius alumina thick plate layer, 4 to 6 small-radius thin alumina sheets or small-radius lightweight quartz layers, and a large-radius alumina thick plate layer; among them, the multi-layer ceramic substrate green body and the small-radius thin alumina sheets are placed on the same layer between two large-radius alumina thick plate layers.

[0015] Preferably, after the multi-layer ceramic substrate green body is placed in the center of a self-made substrate warping prevention device, a small amount of nano-alumina powder is covered on the bottom of the green body for pressureless sintering.

[0016] Preferably, after pressureless sintering, the organic substances in the multilayer ceramic substrate having excellent interlayer bonding are volatilized, and the main phase is aluminum oxide.

[0017] The present invention adopts the above-mentioned method for preparing a multilayer ceramic substrate with excellent interlayer bonding, and the beneficial effects are as follows: (1) Preheating the cast sheet in the present invention makes it easier for the molecules or atoms on the surface of the cast sheet to diffuse and react during the lamination and dry pressing process, and the contact surfaces between the cast sheets are more likely to bond and fuse, thereby improving the interlayer bonding force and making the microstructure of the contact surface more compact and uniform, which helps to reduce defects in the interlayer interface, such as pores and cracks, thereby improving the overall performance of the material; in addition, preheating makes it easier for the cast sheet to adapt to pressure changes during the lamination and dry pressing process, reduces the generation of interface stress, and helps to avoid interface cracking or delamination during the subsequent sintering process; (2) The integrated debinding and sintering system of the present invention accurately determines the debinding temperature range according to the mass change of the cast sheet at different temperatures, optimizes the heating rate and holding time during the debinding process, ensures the efficiency and stability of the debinding process, and effectively reduces the cracking ratio of the multilayer ceramic packaging substrate after sintering; (3) The green body cast from the ceramic slurry of the present invention has moderate viscosity and softness. After preheating, the layers are laminated so that the particles between the layers are embedded in each other and closely bonded. A specific debinding and sintering integration system is designed through thermogravimetric experiments to achieve densification and smooth sintering of the ceramic substrate under pressureless conditions, which can improve the interlayer bonding of the multilayer ceramic substrate at a low cost.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A curve diagram of the debinding and sintering integration system in Example 1 of a method for preparing a multilayer ceramic substrate with excellent interlayer bonding of the present invention; Figure 2 It is a curve diagram of the debinding and sintering integration system in Example 2 of a method for preparing a multilayer ceramic substrate with excellent interlayer bonding of the present invention; Figure 3 The XRD diagram of the sintered sample in Example 1 of the method for preparing a multilayer ceramic substrate with excellent interlayer bonding of the present invention; Figure 4 This is a SEM image of the side bonding surface of the sintered sample in Example 1 of a method for preparing a multilayer ceramic substrate with excellent interlayer bonding of the present invention. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0021] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0022] Embodiment 1 A method for preparing a multilayer ceramic substrate with excellent interlayer bonding, comprising the following steps: Step S1, add 40g of aluminum oxide powder, 5g of chromium oxide powder, and 5g of yttrium oxide powder into a ball mill, use a planetary ball mill to mill, the ball-to-material ratio is 2:1, the rotation speed is 300r / min, the mixing time is 240min, and the powder after ball milling is passed through a 60-mesh sieve to obtain a mixed powder.

[0023] Step S2: add 6 g of polyvinyl alcohol, 6 g of polyethylene glycol, 10 g of ethyl acetate and 15 g of ethanol into a beaker, and stir evenly with a magnetic stirrer to obtain an organic mixed slurry.

[0024] Step S3, weigh 15 g of the mixed powder into a mortar, add 5 g of the organic mixed slurry, stir evenly, and then perform vacuum defoaming on the slurry for 60 minutes to obtain a slurry.

[0025] Step S4, slowly pouring the slurry into a tape casting machine for tape casting preforming, cutting the preformed green body into the size of the mold radius and putting it into an oven for preheating at a preheating temperature of 95°C.

[0026] Step S5, after preheating, 11 green bodies are neatly stacked and placed in a mold for dry pressing to obtain a disc-shaped green body. The pressing pressure is 100 MPa and the holding time is 5 minutes.

[0027] like Figure 1 As shown, the green body is placed in a self-made anti-substrate warping device for pressureless sintering. When the temperature is less than 180°C, the heating rate is set to 1~1.5°C / min, and the temperature is kept at 180°C for 60 minutes. When the temperature is greater than 180°C, the heating rate is maintained at 1~1.5°C / min, and the temperature is kept at 285°C for 60 minutes. When the temperature is greater than 285°C, the heating rate is maintained at 1~1.5°C / min, and the temperature is raised to 500°C, and the temperature is kept at 60 minutes. When the temperature is greater than 500°C, the heating rate is adjusted to 2~3°C / min, and the temperature is raised to 700°C. The heating rate is adjusted to 5~10°C / min again, and the temperature is raised to 1550°C. Keep warm for 300 minutes. After the sintering process is completed, the cooling rate is set to 2°C / min. After it drops to 1300°C, the cooling rate is adjusted to 5°C / min. After cooling to 500°C, it is cooled naturally, as shown Figure 3-Figure 4 As shown, a multilayer ceramic substrate with excellent interlayer bonding is obtained.

[0028] Embodiment 2 A method for preparing a multilayer ceramic substrate with excellent interlayer bonding, comprising the following steps: Step S1, add 42g of aluminum oxide powder, 4g of chromium oxide powder, and 4g of yttrium oxide powder into a ball mill, use a planetary ball mill to mill, the ball-to-material ratio is 2:1, the rotation speed is 300r / min, the mixing time is 240min, and the powder after ball milling is passed through a 60-mesh sieve to obtain a mixed powder.

[0029] Step S2: Add 4 g of polyvinyl alcohol, 4 g of polyethylene glycol, 12 g of ethyl acetate and 20 g of ethanol into a beaker, and stir evenly with a magnetic stirrer to obtain an organic mixed slurry.

[0030] Step S3, weigh 10 g of the mixed powder into a mortar, add 4 g of the organic mixed slurry, stir evenly, and then perform vacuum defoaming on the slurry for 40 minutes to obtain a slurry.

[0031] Step S4, slowly pouring the slurry into a tape casting machine for tape casting preforming, cutting the preformed green body into the radius size of the mold and putting it into an oven for preheating at a preheating temperature of 90°C.

[0032] Step S5, after preheating, 11 green sheets are neatly stacked and placed in a mold for dry pressing to obtain a disc-shaped green sheet. The pressing pressure is 90 MPa and the holding time is 5 min.

[0033] like Figure 2 As shown, the green body is placed in a self-made anti-substrate warping device for pressureless sintering. When the temperature is less than 180°C, the heating rate is set to 1~1.5°C / min, and the temperature is kept at 180°C for 60 minutes. When the temperature is greater than 180°C, the heating rate is maintained at 1~1.5°C / min, and the temperature is kept at 285°C for 60 minutes. When the temperature is greater than 285°C, the heating rate is maintained at 1~1.5°C / min, and the temperature is kept at 500°C for 60 minutes. When the temperature is greater than 500°C, the heating rate is adjusted to 2~3°C / min, and the temperature is raised to 700°C. The heating rate is adjusted to 5~10°C / min again, and the temperature is raised to 1500°C. Keep warm for 360 minutes, and cool down naturally after the sintering process is completed to obtain a multilayer ceramic substrate with excellent interlayer bonding.

[0034] Embodiment 3 A method for preparing a multilayer ceramic substrate with excellent interlayer bonding, comprising the following steps: Step S1, add 40g of aluminum oxide powder, 7g of chromium oxide powder, and 3g of yttrium oxide powder into a ball mill, use a planetary ball mill to mill, the ball-to-material ratio is 2:1, the rotation speed is 300r / min, the mixing time is 360min, and the powder after ball milling is passed through a 60-mesh sieve to obtain a mixed powder.

[0035] Step S2: add 6 g of polyvinyl alcohol, 6 g of polyethylene glycol, 12 g of ethyl acetate and 17 g of ethanol into a beaker, and stir evenly with a magnetic stirrer to obtain an organic mixed slurry.

[0036] Step S3, weigh 15 g of the mixed powder into a mortar, add 5 g of the organic mixed slurry, stir evenly, and then perform vacuum defoaming on the slurry for 60 minutes to obtain a slurry.

[0037] Step S4, slowly pouring the slurry into a tape casting machine for tape casting preforming, cutting the preformed green body into the radius size of the mold and putting it into an oven for preheating, and the preheating temperature is 100°C.

[0038] Step S5: After preheating, 11 green bodies are neatly stacked and placed in a mold for dry pressing to obtain a disc-shaped green body. The pressing pressure is 100 MPa and the holding time is 6 minutes.

[0039] The green body is placed in a homemade anti-substrate warping device for pressureless sintering. When the temperature is less than 180°C, the heating rate is set to 1~1.5°C / min, and the temperature is kept at 180°C for 60 minutes. When the temperature is greater than 180°C, the heating rate is maintained at 1~1.5°C / min, and the temperature is raised to 285°C, and the temperature is kept for 60 minutes. When the temperature is greater than 285°C, the heating rate is maintained at 1~1.5°C / min, and the temperature is raised to 500°C, and the temperature is kept for 60 minutes. When the temperature is greater than 500°C, the heating rate is adjusted to 2~3°C / min, and the temperature is raised to 700°C, and the heating rate is adjusted again to 5~10°C / min, and the temperature is raised to 1550°C. Keep warm for 330 minutes, and cool down naturally after the sintering process is completed to obtain a multilayer ceramic substrate with excellent interlayer bonding.

[0040] Embodiment 4 A method for preparing a multilayer ceramic substrate with excellent interlayer bonding, comprising the following steps: Step S1, add 44g of aluminum oxide powder, 3g of chromium oxide powder, and 3g of yttrium oxide powder into a ball mill, use a planetary ball mill to mill, the ball-to-material ratio is 2:1, the rotation speed is 300r / min, the mixing time is 360min, and the powder after ball milling is passed through a 60-mesh sieve to obtain a mixed powder.

[0041] Step S2: Add 5 g of polyvinyl alcohol, 5 g of polyethylene glycol, 15 g of ethyl acetate and 26 g of ethanol into a beaker, and stir evenly with a magnetic stirrer to obtain an organic mixed slurry.

[0042] Step S3, weigh 15 g of the mixed powder into a mortar, add 4 g of the organic mixed slurry, stir evenly, and then perform vacuum defoaming on the slurry for 60 minutes to obtain a slurry.

[0043] Step S4, slowly pouring the slurry into a tape casting machine for tape casting preforming, cutting the preformed green body into the radius size of the mold and putting it into an oven for preheating, and the preheating temperature is 100°C.

[0044] Step S5, after preheating, 11 green bodies are neatly stacked and placed in a mold for dry pressing to obtain a disc-shaped green body. The pressing pressure is 100 MPa and the holding time is 8 minutes.

[0045] The green body is placed in a self-made anti-substrate warping device for pressureless sintering. When the temperature is less than 180°C, the heating rate is set to 1~1.5°C / min, and the temperature is kept at 180°C for 60 minutes. When the temperature is greater than 180°C, the heating rate is maintained at 1~1.5°C / min, and the temperature is raised to 285°C and kept for 60 minutes. When the temperature is greater than 285°C, the heating rate is maintained at 1~1.5°C / min, and the temperature is raised to 500°C and kept for 60 minutes. When the temperature is greater than 500°C, the heating rate is adjusted to 2~3°C / min, and the temperature is raised to 700°C, and the heating rate is adjusted to 5~10°C / min again, and the temperature is raised to 1600°C. Keep warm for 360 minutes, and cool down naturally after the sintering process is completed to obtain a multilayer ceramic substrate with excellent interlayer bonding.

[0046] Therefore, the present invention adopts the above-mentioned method for preparing a multilayer ceramic substrate with excellent interlayer bonding, which can achieve good interlayer bonding and densification of the multilayer alumina ceramic substrate under pressureless conditions, and solve the problems of long cycle, low efficiency, high energy consumption and expensive and fragile hot pressing molds in the traditional high-temperature hot pressing sintering process.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a multilayer ceramic substrate with excellent interlayer bonding, characterized in that: The following steps are involved: Step S1, mixing aluminum oxide powder, chromium oxide powder and yttrium oxide powder, ball-milling the mixture, and then sieving the mixture to obtain a mixed powder; Step S2, mixing and stirring the binder, plasticizer, dispersant and solvent to obtain an organic mixed slurry; Step S3, mixing the mixed powder and the organic mixed slurry, stirring evenly, and then vacuum degassing to obtain a slurry; Step S4, performing tape casting preforming on the slurry, and then preheating the tape casting preformed green body in an oven and then laminating and dry pressing the green body to obtain a multi-layer ceramic substrate green body; Step S5: pressurelessly sintering the green body of the multilayer ceramic substrate by a specific debinding and sintering integration system, thereby obtaining a multilayer ceramic substrate with excellent interlayer bonding.

2. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 1, characterized in that: In step S1, the aluminum oxide powder, the chromium oxide powder and the yttrium oxide powder are all micro-nano-grade; the mass ratio of the aluminum oxide powder, the chromium oxide powder and the yttrium oxide powder is 80-90:5-15:5-10.

3. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 2, characterized in that: When ball milling, the ball-to-material ratio is 0.5:1~2:1, the rotation speed is 100~300r / min, the mixing time is 240~360min; the sieve is 60~80 mesh.

4. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 1, characterized in that: In step S2, the binder, plasticizer, dispersant and solvent are polyvinyl alcohol, polyethylene glycol, ethyl acetate and ethanol respectively; and the mass ratio thereof is 10-30:10-30:30-50:50-70.

5. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 1, characterized in that: In step S3, the added mass of the organic mixed slurry is 25-50% of the mass of the mixed powder; Among them, the vacuum defoaming time is 30~60min.

6. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 1, characterized in that: In step S4, the preheating temperature is 80-110°C; the lamination dry pressing pressure is 80-120 MPa, and the holding time is 5-20 min.

7. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 1, characterized in that: In step S5, the specific debinding and sintering integration system is as follows: when the temperature is less than or equal to 180°C, the heating rate is set to 1~3°C / min, and the temperature is kept at 150~200°C for 10~90min; when the temperature is greater than 180°C and less than 285°C, the heating rate is set to 1~3°C / min, and the temperature is kept at 200~300°C for 10~90min; when the temperature is greater than 285°C and less than 500°C, the heating rate is set to 1~3°C / min, and the temperature is kept at 500°C for 90~150min; when the temperature is greater than 500°C and less than 700°C, the heating rate is set to 1~3°C / min; when the temperature is greater than 700°C and less than 1300°C, the heating rate is adjusted to 3~15°C / min, the temperature is raised to 1300~1800°C, and the temperature is kept for 200~420min.

8. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 7, characterized in that: In step S5, the multi-layer ceramic substrate green body is placed in a self-made substrate warping prevention device for pressureless sintering; The structure of the homemade anti-substrate warping device is, from top to bottom, a large-radius alumina thick plate layer, 4 to 6 small-radius thin alumina sheets or small-radius lightweight quartz layers, and a large-radius alumina thick plate layer; among them, the multi-layer ceramic substrate green body and the small-radius thin alumina sheets are placed on the same layer between two large-radius alumina thick plate layers.

9. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 8, characterized in that: After placing the multilayer ceramic substrate green body into the center of a homemade anti-substrate warping device, a small amount of nano-alumina powder is covered on the bottom of the body for pressureless sintering.

10. The method for preparing a multilayer ceramic substrate with excellent interlayer bonding according to claim 9, characterized in that: After pressureless sintering, the organic matter in the multilayer ceramic substrate with excellent interlayer bonding is volatilized, and the main phase is aluminum oxide.

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