A silicon nitride cast film laminated material, its laminating process and application

Abstract

The application discloses a kind of silicon nitride casting film laminated material and its laminated process and application, it is related to ceramic substrate technical field.Silicon nitride casting film laminated process, including the following steps: preparation silicon nitride casting film;The silicon nitride casting film is added layer by layer to preset thickness, vacuum packaging, cold isostatic pressing;Vacuum packaging of material is removed, secondary vacuum packaging, warm isostatic pressing, obtain silicon nitride casting film laminated material.Silicon nitride casting film laminated process, after casting film laminated film, vacuum packaging and cold isostatic pressing, improve interlayer adhesion;Then remove vacuum packaging, secondary vacuum packaging and warm isostatic pressing treatment, can further discharge gas in laminated structure, fill residual pore, improve the density of material, improve uniformity, enhance interlayer bonding force.

Description

Technical Field

[0001] This invention relates to the field of ceramic substrate technology, and more specifically, to a silicon nitride cast film laminate material, its laminate process, and its applications. Background Technology

[0002] Silicon nitride ceramics have high thermal conductivity, mechanical properties and corrosion resistance, and can be widely used as heat dissipation substrates, thermal management materials or insulating layers in high-power power modules.

[0003] Silicon nitride ceramic substrates are generally prepared by tape casting. Existing processes for preparing silicon nitride tape-cast laminated materials typically involve sequentially stacking the tape-cast films, vacuum encapsulating them, and performing warm isostatic pressing. However, after pressing, the preform is prone to bubbling or film separation. This is because during the tape casting process of nitride ceramics, nitrides themselves have weak adsorption capacity for dispersants and binders, meaning there is less organic matter coated on the surface of the ceramic powder. This results in insufficient adhesion and flexibility during stacking, preventing the films from effectively fusing together. If only a specific point fails to bond, a bubble forms (the space is filled with air). If the area where bonding fails is large, delamination between the films occurs.

[0004] Patent CN115763070A proposes a method for improving the stacking bubbles in MLCCs. This method alters the morphology and structure of the cast film by adjusting the material process parameters and formulation, creating channels for bubble expulsion during the stacking process. This suppresses the formation of bubbles in the stacked blocks. Simultaneously, during packaging and pressing, residual micro-bubbles can be effectively expelled from the blocks before softening and pressing, ensuring thorough bonding between the layers and preventing delamination or splitting caused by localized gas accumulation. However, this method requires high-precision stacking of the film layers and ensuring internal consistency and uniformity, placing overly stringent technical requirements and making it difficult to apply to large-scale industrial production. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects and shortcomings of existing silicon nitride cast film stacks, which are prone to bubbling or film separation, and to provide a silicon nitride cast film stacking process.

[0006] Another object of the present invention is to provide a silicon nitride cast film laminate material.

[0007] Another object of the present invention is to provide an application of silicon nitride cast film laminate material in the preparation of ceramic substrates.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] This invention protects a silicon nitride casting film stacking process, comprising the following steps:

[0010] S1, preparing silicon nitride cast film;

[0011] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness, vacuum-sealed, and cold isostatically pressed;

[0012] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0013] In the silicon nitride cast film stacking process of the present invention, after the cast film is stacked, it is vacuum sealed and cold isostatically pressed. During the pressing process, the binder is partially migrated to the film surface due to compression, increasing the concentration of binder on the film surface and even forming a thin layer of binder, thereby improving the interlayer adhesion. Then, the vacuum sealing is removed, which releases stress and allows residual gas in the layers to move to the interlayer interface, while evaporating solvent (a small amount of solvent contained in the film is squeezed out under static pressure). A second vacuum sealing and warm isostatic pressing treatment can fill the residual pores formed after the gas is discharged from the interlayer after the vacuum sealing is removed, thereby improving the density of the material, improving uniformity, and enhancing the interlayer bonding force.

[0014] In some embodiments, the method for preparing the silicon nitride cast film in step S1 includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry, casting and molding, drying to obtain silicon nitride cast film.

[0015] In some embodiments, the silicon nitride slurry comprises the following components by weight:

[0016]

[0017] In some embodiments, the mass ratio of the plasticizer to the binder is (0.5-0.9):1.

[0018] The conventional amount of plasticizer added is 30-50% of the weight of the binder. The inventors discovered that appropriately increasing the proportion of plasticizer is beneficial to softening the binder, improving the wettability between the binder and the silicon nitride ceramic powder, and making the binder more evenly distributed between the silicon nitride ceramic powder, thereby improving the bonding force of the powder and enhancing the density and mechanical strength of the laminated material.

[0019] In some embodiments, the sintering aids include, but are not limited to, oxides of Mg and rare earth oxides.

[0020] Preferably, the sintering aid is a Mg oxide and a rare earth oxide in a mass ratio of (1-5):(1-5).

[0021] Preferably, the oxide of Mg is MgO and / or magnesium silicate.

[0022] Preferably, the rare earth oxide is Re2O3.

[0023] In some embodiments, the plasticizer is dioctyl phthalate (DOP).

[0024] In some embodiments, the adhesive is polyvinyl butyral (PVB).

[0025] In some embodiments, the dispersant is a phosphate ester.

[0026] In some embodiments, the solvent is toluene and / or alcohol.

[0027] In some embodiments, during step S2, when the silicon nitride cast films are stacked layer by layer, adjacent films do not completely cover each other, leaving vent holes at the edges of the film layers. Preferably, the dimensional difference between the edges of the two films is 1-4 mm. The vent holes help to expel air between layers and reduce the residue of air bubbles between layers.

[0028] In some embodiments, the preset thickness in step S2 is 0.5-2 mm.

[0029] In some embodiments, the process conditions for cold isostatic pressing in step S2 are: temperature of 25±5℃ and pressure of 50-80Mpa.

[0030] The cold isostatic pressing (CIP) process applies uniform pressure using a liquid medium at room temperature to press the cast film stack into a uniform block. The organic matter coating the silicon nitride ceramic powder surface is primarily a binder. During pressing, some of this binder migrates to the film surface due to compression, increasing the binder concentration and potentially forming a thin binder layer, thus improving interlayer adhesion. This process uses only cold isostatic pressing, without utilizing high temperatures to increase the binder concentration on the film surface, because the binder is an organic substance, and its melting rate is uncontrollable at high temperatures. Furthermore, at high temperatures, other organic substances and solvents migrate too quickly; since they are lighter than the binder, their migration speed is even faster, resulting in less binder migrating to the surface. Additionally, being immersed in solutions of other organic substances and solvents reduces viscosity.

[0031] In some embodiments, the process conditions for the isostatic pressing in step S3 are: temperature 70±10℃ and pressure 80-150Mpa.

[0032] The present invention, which uses vacuum encapsulation for warm isostatic pressing after cold isostatic pressing (CIP), has the following advantages:

[0033] (1) Improved density: Warm isostatic pressing after cold isostatic pressing can reduce defects such as microcracks and pores in the material, and the adjacent film layers that are bonded together during the vacuum process are adhered together, further improving the density of the material. The introduction of temperature makes the material easier to deform and rearrange under pressure, thereby filling more pores (the pores are mainly the residual pores formed after the gas from the vacuum sealing is removed and discharged from the interlayer).

[0034] (2) Improve uniformity: The two pressing processes help to eliminate the local non-uniformity that may be left by cold isostatic pressing, and the combination of different temperatures and pressures can optimize the microstructure of the material, making the overall structure more uniform.

[0035] (3) Enhanced bonding force: The isostatic pressing at higher temperatures can promote diffusion and bonding between particles, thereby enhancing the internal bonding force of the material.

[0036] (4) Reduce residual stress: Warm isostatic pressing can help release residual stress that may be introduced during cold isostatic pressing, and improve the stability of the material; this dual pressing process helps to improve the consistency of product quality in mass production.

[0037] Prior to this invention, the pressure of warm isostatic pressing is much higher than that of cold isostatic pressing. Increased temperature enhances the plastic deformation capacity of the billet, while higher pressure is more beneficial for improving the density of the billet. Simultaneously, since cold isostatic pressing has already initially compacted the material, warm isostatic pressing requires even higher pressure to overcome the internal stress of the material and further improve its microstructure (promoting the closure of internal pores and particle rearrangement). Therefore, higher pressure is needed in this step to achieve increased density.

[0038] Whether it is cold isostatic pressing or warm isostatic pressing, pressure is the dominant factor in increasing the density of the billet, while the length of holding time has no significant effect.

[0039] Preferably, in step S2, the holding time for cold isostatic pressing is 5-10 minutes.

[0040] Preferably, in step S3, the holding time for the isostatic pressing is 1-10 minutes.

[0041] In some embodiments, the vacuum sealing or secondary vacuum sealing has a vacuum level of -0.08 MPa to -0.1 MPa. Vacuum sealing facilitates the extraction of interlayer gas, enhances the adhesion between diaphragms, reduces external environmental contamination, and better controls the transmission of pressure media.

[0042] This invention protects a silicon nitride cast film laminate material, which is manufactured by the aforementioned silicon nitride cast film laminate process.

[0043] This invention protects the application of a silicon nitride cast film laminate material in the preparation of ceramic substrates.

[0044] This invention protects the application of a low-smoke-density flame-retardant polyethylene material in the preparation of cable sheaths.

[0045] Compared with the prior art, the beneficial effects of the present invention are:

[0046] This invention provides a silicon nitride cast film stacking process in which, after the cast films are stacked, vacuum sealing and cold isostatic pressing are performed. During the pressing process, the binder partially migrates to the film surface due to compression, increasing the binder concentration on the film surface and even forming a thin binder layer, thereby improving interlayer adhesion. Then, the vacuum sealing is removed, which releases stress and allows residual gas within the layers to move to the interlayer interface, while simultaneously expelling volatile solvents. A second vacuum sealing and warm isostatic pressing process fills the residual pores formed after the gas is expelled from the interlayer after the vacuum sealing is removed, improving the material density, uniformity, and interlayer bonding. Attached Figure Description

[0047] Figure 1 This is a microscopic morphology diagram of a good product obtained by a silicon nitride casting film stacking process according to the present invention.

[0048] Figure 2 This is a microscopic morphology image of a sample containing bubbles obtained by a silicon nitride casting film stacking process according to the present invention.

[0049] Figures 3-5 The images show the microstructure of the layered sample obtained by the silicon nitride casting film stacking process in the comparative examples of this invention. Detailed Implementation

[0050] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0051] Example 1

[0052] A silicon nitride casting film stacking process includes the following steps:

[0053] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0054] The silicon nitride slurry comprises the following components in parts by weight:

[0055]

[0056] The plasticizer content is 50% of the weight of the binder.

[0057] Preferably, the sintering aid is MgO and Re2O3 in a mass ratio of 5:1;

[0058] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0059] Preferably, the adhesive is polyvinyl butyral (PVB).

[0060] Preferably, the dispersant is a phosphate ester.

[0061] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0062] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0063] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0064] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and two vent holes are provided on the same edge of the film.

[0065] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature of 25℃, pressure of 80MPa, and holding time of 5min.

[0066] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0067] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 70℃, pressure 100MPa, and holding time 10min.

[0068] Example 2

[0069] A silicon nitride casting film stacking process includes the following steps:

[0070] S1. Prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film.

[0071] The silicon nitride slurry comprises the following components in parts by weight:

[0072]

[0073] The plasticizer content is 30% of the weight of the binder.

[0074] Preferably, the sintering aid is MgO and Re2O3 in a mass ratio of 5:2;

[0075] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0076] Preferably, the adhesive is polyvinyl butyral (PVB).

[0077] Preferably, the dispersant is a phosphate ester.

[0078] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0079] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0080] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0081] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and two air vents are provided on the diagonal of the film.

[0082] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature of 25℃, pressure of 50MPa, and holding time of 5min.

[0083] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0084] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 80℃, pressure 80MPa, and holding time 10min.

[0085] Example 3

[0086] A silicon nitride casting film stacking process includes the following steps:

[0087] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0088] The silicon nitride slurry comprises the following components in parts by weight:

[0089]

[0090] The plasticizer content is 50% of the weight of the binder.

[0091] Preferably, the sintering aid is magnesium silicate and Re2O3 in a mass ratio of 5:1;

[0092] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0093] Preferably, the adhesive is polyvinyl butyral (PVB).

[0094] Preferably, the dispersant is a phosphate ester.

[0095] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0096] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0097] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0098] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and two air vents are provided on the diagonal of the film.

[0099] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature 30℃, pressure 50MPa, and holding time 5min.

[0100] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0101] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 70℃, pressure 150MPa, and holding time 5min.

[0102] Example 4

[0103] A silicon nitride casting film stacking process includes the following steps:

[0104] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0105] The silicon nitride slurry comprises the following components in parts by weight:

[0106]

[0107] The plasticizer content is 50% of the weight of the binder.

[0108] Preferably, the sintering aid is MgO and Re2O3 in a mass ratio of 5:1;

[0109] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0110] Preferably, the adhesive is polyvinyl butyral (PVB).

[0111] Preferably, the dispersant is a phosphate ester.

[0112] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0113] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0114] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0115] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one vent hole on each of the two adjacent edges.

[0116] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature 30℃, pressure 70MPa, and holding time 5min.

[0117] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0118] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 80℃, pressure 120MPa, and holding time 7min.

[0119] Example 5

[0120] A silicon nitride casting film stacking process includes the following steps:

[0121] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0122] The silicon nitride slurry comprises the following components in parts by weight:

[0123]

[0124] The plasticizer content is 50% of the weight of the binder.

[0125] Preferably, the sintering aid is MgO and Re2O3 in a mass ratio of 5:3;

[0126] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0127] Preferably, the adhesive is polyvinyl butyral (PVB).

[0128] Preferably, the dispersant is a phosphate ester.

[0129] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0130] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0131] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0132] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one vent hole on each of the two parallel sides.

[0133] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature of 25℃, pressure of 70MPa, and holding time of 10min.

[0134] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0135] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 75℃, pressure 120MPa, and holding time 10min.

[0136] Example 6

[0137] A silicon nitride casting film stacking process includes the following steps:

[0138] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0139] The silicon nitride slurry comprises the following components in parts by weight:

[0140]

[0141] The plasticizer content is 60% of the weight of the binder.

[0142] Preferably, the sintering aid is magnesium silicate and Re2O3 in a mass ratio of 5:3;

[0143] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0144] Preferably, the adhesive is polyvinyl butyral (PVB).

[0145] Preferably, the dispersant is a phosphate ester.

[0146] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0147] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0148] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0149] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one vent hole on each of the two parallel sides.

[0150] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature of 25℃, pressure of 70MPa, and holding time of 10min.

[0151] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0152] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 75℃, pressure 120MPa, and holding time 10min.

[0153] Example 7

[0154] A silicon nitride casting film stacking process includes the following steps:

[0155] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0156] The silicon nitride slurry comprises the following components in parts by weight:

[0157]

[0158] The plasticizer content is 65% of the weight of the binder.

[0159] Preferably, the sintering aid is MgO and Re2O3 in a mass ratio of 1:1;

[0160] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0161] Preferably, the adhesive is polyvinyl butyral (PVB).

[0162] Preferably, the dispersant is a phosphate ester.

[0163] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0164] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0165] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0166] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one vent hole on each of the two adjacent edges.

[0167] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature 30℃, pressure 70MPa, and holding time 5min.

[0168] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0169] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 80℃, pressure 120MPa, and holding time 7min.

[0170] Example 8

[0171] A silicon nitride casting film stacking process includes the following steps:

[0172] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0173] The silicon nitride slurry comprises the following components in parts by weight:

[0174]

[0175] The plasticizer content is 65% of the weight of the binder.

[0176] Preferably, the sintering aid is magnesium silicate and Re2O3 in a mass ratio of 1:1;

[0177] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0178] Preferably, the adhesive is polyvinyl butyral (PVB).

[0179] Preferably, the dispersant is a phosphate ester.

[0180] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0181] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0182] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0183] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one vent hole on each of the four sides.

[0184] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature 30℃, pressure 70MPa, and holding time 5min.

[0185] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0186] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 80℃, pressure 120MPa, and holding time 7min.

[0187] Example 9

[0188] A silicon nitride casting film stacking process includes the following steps:

[0189] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0190] The silicon nitride slurry comprises the following components in parts by weight:

[0191]

[0192] The plasticizer content is 70% of the weight of the binder.

[0193] Preferably, the sintering aid is MgO and Re2O3 in a mass ratio of 5:1;

[0194] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0195] Preferably, the adhesive is polyvinyl butyral (PVB).

[0196] Preferably, the dispersant is a phosphate ester.

[0197] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0198] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0199] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0200] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one vent hole on each of the four sides.

[0201] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature 30℃, pressure 70MPa, and holding time 5min.

[0202] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0203] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 80℃, pressure 120MPa, and holding time 7min.

[0204] Example 10

[0205] A silicon nitride casting film stacking process includes the following steps:

[0206] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0207] The silicon nitride slurry comprises the following components in parts by weight:

[0208]

[0209] The plasticizer content is 77% of the weight of the binder.

[0210] Preferably, the sintering aid is MgO and Re2O3 in a mass ratio of 1:5;

[0211] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0212] Preferably, the adhesive is polyvinyl butyral (PVB).

[0213] Preferably, the dispersant is a phosphate ester.

[0214] Preferably, the solvent is toluene and alcohol in a mass ratio of 2:1.

[0215] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0216] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0217] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one vent hole on each of the four sides.

[0218] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature 30℃, pressure 70MPa, and holding time 5min.

[0219] S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0220] The vacuum degree of the secondary vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 80℃, pressure 120MPa, and holding time 7min.

[0221] Comparative Example 1

[0222] A silicon nitride casting film stacking process includes the following steps:

[0223] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0224] The silicon nitride slurry comprises the following components in parts by weight:

[0225]

[0226] The plasticizer content is 30% of the weight of the binder.

[0227] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0228] Preferably, the adhesive is polyvinyl butyral (PVB).

[0229] Preferably, the dispersant is a phosphate ester.

[0230] Preferably, the solvent is toluene and alcohol.

[0231] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0232] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed in a vacuum bag, and cold isostatically pressed to obtain a silicon nitride cast film laminate material.

[0233] When the silicon nitride cast films are stacked layer by layer, the films are the same size and fit together completely;

[0234] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature of 25℃, pressure of 50MPa, and holding time of 5min.

[0235] Comparative Example 2

[0236] A silicon nitride casting film stacking process includes the following steps:

[0237] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0238] The silicon nitride slurry comprises the following components in parts by weight:

[0239]

[0240]

[0241] The plasticizer content is 70% of the weight of the binder.

[0242] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0243] Preferably, the adhesive is polyvinyl butyral (PVB).

[0244] Preferably, the dispersant is a phosphate ester.

[0245] Preferably, the solvent is toluene and alcohol.

[0246] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0247] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed in a vacuum bag, and cold isostatically pressed to obtain a silicon nitride cast film laminate material.

[0248] When the silicon nitride cast films are stacked layer by layer, the films are of the same size and fit together completely.

[0249] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature 30℃, pressure 70MPa, and holding time 5min.

[0250] Comparative Example 3

[0251] A silicon nitride casting film stacking process includes the following steps:

[0252] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0253] The silicon nitride slurry comprises the following components in parts by weight:

[0254]

[0255] The plasticizer content is 70% of the weight of the binder.

[0256] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0257] Preferably, the adhesive is polyvinyl butyral (PVB).

[0258] Preferably, the dispersant is a phosphate ester.

[0259] Preferably, the solvent is toluene and alcohol.

[0260] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0261] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum sealed in a vacuum bag, and isostatically pressed to obtain a silicon nitride cast film laminate material.

[0262] When the silicon nitride cast films are stacked layer by layer, the films are the same size and fit together completely; the difference in size between the edges of the two films is 1 mm, and there is one vent hole on each of the four edges;

[0263] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions of the isostatic pressing are: temperature 80℃, pressure 120MPa, and holding time 7min.

[0264] Comparative Example 4

[0265] A silicon nitride casting film stacking process includes the following steps:

[0266] S1, prepare silicon nitride slurry, cast it into a film, and dry it to obtain a silicon nitride cast film;

[0267] The silicon nitride slurry comprises the following components in parts by weight:

[0268]

[0269] The plasticizer content is 70% of the weight of the binder.

[0270] Preferably, the plasticizer is dioctyl phthalate (DOP).

[0271] Preferably, the adhesive is polyvinyl butyral (PVB).

[0272] Preferably, the dispersant is a phosphate ester.

[0273] Preferably, the solvent is toluene and alcohol.

[0274] The method for preparing the silicon nitride slurry includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, and then adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry.

[0275] S2, the silicon nitride cast film is stacked layer by layer to a preset thickness (1mm), vacuum-sealed using a vacuum bag, and then cold isostatically pressed;

[0276] When the silicon nitride cast film is stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one vent hole on each of the four sides.

[0277] The vacuum degree of the vacuum sealing is -0.1MPa; the process conditions for the cold isostatic pressing are: temperature 30℃, pressure 70MPa, and holding time 5min.

[0278] S3, the material obtained in step S2 is subjected to isostatic pressing to obtain a silicon nitride cast film laminate material.

[0279] The process conditions for the isostatic pressing are: temperature 80℃, pressure 120MPa, and holding time 7min.

[0280] Performance testing

[0281] 100 samples each from Examples 1-10 and Comparative Examples 1-4 were randomly selected, and the microstructure of the samples was characterized and tested.

[0282] The testing method is as follows: The microstructure and interlayer bonding of the laminated samples are observed using an optical microscope. Specifically, a 100*1mm section is selected at the interface of each sample. 2 The area is scanned, the defects in the main observation area are observed, and the number and shape structure changes of bubbles are recorded (round holes are recorded as bubbles, obvious layered interfaces are recorded as layering, and samples with both bubbles and layering are collectively recorded as layering).

[0283] The microstructure of the good product in Example 1 is as follows: Figure 1 As shown.

[0284] The microstructure of the sample containing bubbles in Comparative Example 1 is as follows: Figure 2 As shown.

[0285] The microstructure of the sample with stratification in Comparative Example 1 is as follows: Figure 3 As shown.

[0286] The microstructure of the layered sample in Comparative Example 2 is as follows: Figure 4 As shown.

[0287] The microstructure of the layered sample in Comparative Example 3 is as follows: Figure 5 As shown.

[0288] The number of samples with air bubbles and the number of samples with delamination were counted for all test samples, and the yield rate was calculated. The results are shown in Table 1.

[0289] Table 1

[0290]

[0291]

[0292] As can be seen from Table 1, the silicon nitride casting film stacking process of the present invention can reduce bubbles and achieve a yield of over 94%.

[0293] Comparing Example 1 and Example 2, or comparing Example 9 and Example 10, it can be seen that increasing the proportion of plasticizer in the binder can reduce bubbles and improve product yield.

[0294] As can be seen from Examples 2 and 9 and Comparative Examples 1-2, when the lamination process does not include venting holes and does not involve the steps of removing the vacuum bag and performing warm isostatic pressing, delamination is more likely to occur, resulting in a significant decrease in product yield. In Comparative Example 3, warm isostatic pressing is used directly after encapsulation instead of cold isostatic pressing, which reduces the occurrence of air bubbles, but delamination is still likely to occur, resulting in a lower product yield.

[0295] Compared to Example 9, in Comparative Example 3, the vacuum bag was not removed after cold isostatic pressing, and the product was directly subjected to warm isostatic pressing. This significantly increased the probability of delamination and resulted in a lower product yield. The reason is that after cold isostatic pressing, air bubbles remain between the layers, and some adhesive solvents also accumulate. If the vacuum bag is not removed before vacuuming to extract these gases, the product yield will decrease significantly.

[0296] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A silicon nitride casting film stacking process, characterized in that, Includes the following steps: S1, silicon nitride slurry is cast and molded to prepare silicon nitride cast film; S2, the silicon nitride cast film is stacked layer by layer to a preset thickness, vacuum sealed, and cold isostatic pressing is performed; the temperature of the cold isostatic pressing is 25±5℃, and the pressure is 50-80MPa. S3, remove the vacuum seal of the material obtained in step S2, perform a second vacuum seal, and perform warm isostatic pressing. The temperature of the warm isostatic pressing is 70±10℃ and the pressure is 50-80MPa to obtain silicon nitride cast film laminate material. The silicon nitride slurry comprises the following components in parts by weight: 50-60 parts of silicon nitride ceramic powder 1-5 parts of sintering aid, Dispersant 0.1-2 parts, 4.2-5 parts adhesive, Plasticizer 2.52-3.24 parts, Solvent 25-35 parts.

2. The silicon nitride casting film stacking process according to claim 1, characterized in that, In the vacuum packaging or secondary vacuum packaging, the vacuum degree is -0.08 MPa to -0.1 MPa.

3. The silicon nitride casting film stacking process according to claim 1, characterized in that, The preparation method of silicon nitride cast film in step S1 includes: mixing and ball milling silicon nitride ceramic powder, sintering aid, dispersant and solvent, adding plasticizer and binder and mixing evenly to obtain silicon nitride slurry, casting and molding, drying to obtain silicon nitride cast film.

4. The silicon nitride casting film stacking process according to claim 1, characterized in that, The plasticizer is dioctyl phthalate; the binder is polyvinyl butyral.

5. A silicon nitride cast film laminate material, characterized in that, It is made by a silicon nitride casting film stacking process according to any one of claims 1-4.

6. The application of the silicon nitride cast film laminate material according to claim 5 in the preparation of ceramic substrates.

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