Silicon nitride cast film laminated material as well as lamination process and application thereof

Abstract

The invention discloses a silicon nitride cast film laminated material as well as a lamination process and application thereof, and relates to the technical field of ceramic substrates. The silicon nitride cast film lamination process comprises the following steps: preparing a silicon nitride cast film; superposing the silicon nitride cast film layer by layer to a preset thickness, performing vacuum packaging, and performing cold isostatic pressing; and removing the vacuum package of the material, carrying out secondary vacuum package, and carrying out temperature isostatic pressing to obtain the silicon nitride cast film laminated material. In the lamination process of the silicon nitride cast film, after the cast film is laminated, vacuum packaging and cold isostatic pressing are carried out, so that the interlayer adhesive force is improved; and then vacuum packaging is removed, secondary vacuum packaging is performed, and warm isostatic pressing treatment is performed, so that gas in the laminated structure can be further discharged, residual pores can be filled, the density of the material is improved, the uniformity is improved, and the interlayer binding force is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic substrates, and more specifically to a silicon nitride cast film laminate material and a lamination process and application thereof. Background Art

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

[0003] Silicon nitride ceramic substrates are generally prepared by tape casting. The existing process for preparing silicon nitride tape film laminated materials is generally: the tape film is laminated, vacuum encapsulated and warm isostatically pressed in sequence, but the blank is prone to bubbling or film separation after pressing. The reason is that during the tape casting process of nitride ceramics, the nitride itself has a weak adsorption capacity for dispersants, binders, etc., that is, the organic matter wrapped on the surface of the ceramic powder is relatively small, resulting in the diaphragms being unable to be effectively fused together during lamination due to insufficient viscosity and flexibility. If only a certain position point cannot be fitted, a bubble will form at this place (the space is filled with air). If the area that cannot be fitted is relatively large, the diaphragms will be layered with each other.

[0004] Patent CN115763070A proposes a method for improving the lamination bubbles of MLCC. This method changes the morphology and structure of the cast film by adjusting the batching process parameters and formula, and forms a channel for the discharge of bubbles during the lamination process, thereby inhibiting the occurrence of lamination bubbles. At the same time, during the packaging and uniform pressing process, the residual tiny bubbles can be effectively discharged from the bar before the bar softens and is pressed, so that the layers of the bar are fully pressed together, avoiding the delamination of the bar or the delamination of the bar due to cutting caused by the accumulation of local gas residues. However, it requires high-precision stacking of the film layers and ensures the consistency and uniformity of the internal layers. The technical requirements are too stringent and difficult to apply to large-scale industrial production. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects and shortcomings of the existing silicon nitride cast film stacking, that is, bubbling or film layer separation is prone to occur, 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 stack material.

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

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] The present invention protects a silicon nitride cast film lamination process, comprising the following steps:

[0010] S1, preparing silicon nitride cast film;

[0011] S2, stacking the silicon nitride cast film layer by layer to a preset thickness, vacuum packaging, and cold isostatic pressing;

[0012] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

[0013] In the silicon nitride cast film lamination process of the present invention, after the cast film is laminated, vacuum packaging and cold isostatic pressing are performed, so that the binder partially migrates to the surface of the membrane due to extrusion during the pressing process, the concentration of the binder on the surface of the membrane increases, and even a thin layer of binder is formed, thereby improving the interlayer adhesion; then the vacuum packaging is removed to release the stress, so that the residual gas in the layer moves to the interlayer interface, and the volatile solvent is discharged at the same time (the small amount of solvent contained in the membrane is squeezed out under static pressure); and a second vacuum packaging and warm isostatic pressing treatment can fill the residual pores formed after the gas is discharged from the interlayer after the vacuum packaging is removed, thereby improving the density of the material, improving the uniformity, and enhancing the interlayer bonding strength.

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

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

[0016]

[0017] In some of the 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 have found 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 among 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 aid includes, but is not limited to, Mg oxide and rare earth oxide.

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

[0021] Preferably, the Mg oxide 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 binder 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, in step S2, when the silicon nitride cast film is stacked layer by layer, adjacent film sheets are not completely covered, so that vent holes are left at the edges of the film layers. Preferably, the size difference between the edges of the two film sheets is 1-4 mm. The vent holes help to discharge the air between the layers and reduce the residual bubbles between the layers.

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

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

[0030] The cold isostatic pressing (CIP) can use a liquid medium to apply uniform pressure at room temperature to press the cast film stack into a uniform block. The organic matter wrapped on the surface of the silicon nitride ceramic powder is mainly a binder, which partially migrates to the surface of the diaphragm due to extrusion during the pressing process. The concentration of the binder on the surface of the diaphragm increases, and even a thin layer of binder is formed to improve the interlayer adhesion. In the steps of this process, only cold isostatic pressing is used, and high temperature is not used to increase the binder on the surface of the diaphragm. This is because the binder is an organic matter, and the degree of melting at high temperature is uncontrollable; and at high temperature, other organic matter and solvents will also migrate too fast because they are lighter than the binder and migrate faster. In the end, less binder migrates to the surface, and is soaked in other organic matter and solvent solutions, and the viscosity is reduced.

[0031] In some embodiments, in step S3, the process conditions of warm isostatic pressing are: temperature of 70±10° C. and pressure of 80-150 MPa.

[0032] The present invention uses vacuum packaging to perform warm isostatic pressing again after cold isostatic pressing (CIP), which has the following advantages:

[0033] (1) Improve density: Warm isostatic pressing after cold isostatic pressing can reduce defects such as microcracks and holes in the material, and bond adjacent film layers that are bonded to each other during the vacuum process, 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 residual pores formed after the vacuum packaging gas is removed and discharged from the interlayer).

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

[0035] (3) Enhanced bonding strength: Warm isostatic pressing at higher temperatures can promote diffusion and bonding between particles and enhance the internal bonding strength of the material.

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

[0037] Preferably, the pressure of warm isostatic pressing in the present invention is much higher than that of cold isostatic pressing; the increase in temperature will enhance the plastic deformation ability of the green body, and the higher the pressure, the more conducive it is to improving the density of the green body. At the same time, since the cold isostatic pressing has preliminarily compacted the material, the warm isostatic pressing requires a higher pressure to overcome the internal stress of the material and further improve its microstructure (promote the closure of the internal pores of the material and the rearrangement of the particles). Therefore, a higher pressure is required in this step to achieve an increase in density.

[0038] Whether it is cold isostatic pressing or warm isostatic pressing, pressure is the dominant factor in improving the density of the green body, while the length of the holding time has no obvious effect.

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

[0040] Preferably, in step S3, the holding time of the warm isostatic pressing is 1-10 min.

[0041] In some embodiments, the vacuum degree in the vacuum packaging or secondary vacuum packaging is -0.08Mpa to -0.1Mpa. Vacuum packaging is conducive to the extraction of interlayer gas, enhancing the fit between diaphragms, reducing pollution of the external environment, and better controlling the transmission of pressure medium.

[0042] The invention protects a silicon nitride cast film stacking material, which is made by the silicon nitride cast film stacking process.

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

[0044] The invention discloses application of a low smoke density flame retardant polyethylene material in preparing a cable sheath.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention provides a silicon nitride cast film lamination process. After the cast film is laminated, vacuum packaging and cold isostatic pressing are performed, so that the binder partially migrates to the surface of the membrane due to extrusion during the pressing process, the concentration of the binder on the surface of the membrane increases, and even a thin layer of binder is formed, thereby improving the interlayer adhesion; then the vacuum packaging is removed to release the stress, so that the residual gas in the layer moves to the interface between the layers, and the volatile solvent is discharged at the same time; and the vacuum packaging is performed again and warm isostatic pressing is performed, so that the residual pores formed after the gas is discharged from the layers after the vacuum packaging is removed can be filled, thereby improving the density of the material, improving the uniformity, and enhancing the interlayer bonding force. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a microscopic morphology of a good product obtained by a silicon nitride cast film lamination process of the present invention.

[0048] Figure 2 This is a microscopic morphology of a sample with bubbles obtained by a silicon nitride cast film lamination process of the present invention.

[0049] Figure 3 to Figure 5 They are respectively microscopic morphology images of samples with stratification obtained by the silicon nitride cast film lamination process in the comparative example of the present invention. DETAILED DESCRIPTION

[0050] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, 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 cast film lamination process comprises the following steps:

[0053] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0054] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0055]

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

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

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

[0059] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0063] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

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

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

[0066] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0068] Example 2

[0069] A silicon nitride cast film lamination process comprises the following steps:

[0070] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0071] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0072]

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

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

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

[0076] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0080] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0081] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and two air holes are provided on the diagonal line of the film;

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

[0083] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0085] Example 3

[0086] A silicon nitride cast film lamination process comprises the following steps:

[0087] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0088] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0089]

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

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

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

[0093] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0097] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0098] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and two air holes are provided on the diagonal line of the film;

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

[0100] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0102] Example 4

[0103] A silicon nitride cast film lamination process comprises the following steps:

[0104] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0105] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0106]

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

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

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

[0110] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0114] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0115] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one air hole on each of the two adjacent edges;

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

[0117] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0119] Example 5

[0120] A silicon nitride cast film lamination process comprises the following steps:

[0121] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0122] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0123]

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

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

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

[0127] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0131] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0132] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one air hole on each of the two parallel edges;

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

[0134] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0136] Example 6

[0137] A silicon nitride cast film lamination process comprises the following steps:

[0138] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0139] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0140]

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

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

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

[0144] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0148] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0149] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one air hole on each of the two parallel edges;

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

[0151] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0153] Example 7

[0154] A silicon nitride cast film lamination process comprises the following steps:

[0155] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0156] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0157]

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

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

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

[0161] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0165] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0166] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one air hole on each of the two adjacent edges;

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

[0168] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0170] Example 8

[0171] A silicon nitride cast film lamination process comprises the following steps:

[0172] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0173] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0174]

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

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

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

[0178] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0182] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0183] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one air hole on each of the four edges;

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

[0185] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0187] Example 9

[0188] A silicon nitride cast film lamination process comprises the following steps:

[0189] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0190] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0191]

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

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

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

[0195] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0199] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0200] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one air hole on each of the four edges;

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

[0202] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0204] Example 10

[0205] A silicon nitride cast film lamination process comprises the following steps:

[0206] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0207] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0208]

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

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

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

[0212] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0216] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0217] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one air hole on each of the four edges;

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

[0219] S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

[0221] Comparative Example 1

[0222] A silicon nitride cast film lamination process comprises the following steps:

[0223] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0224] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0225]

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

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

[0228] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0232] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing to obtain a silicon nitride cast film laminate material.

[0233] Wherein, when the silicon nitride cast films are stacked layer by layer, the film pieces are of the same size and fit each other completely;

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

[0235] Comparative Example 2

[0236] A silicon nitride cast film lamination process comprises the following steps:

[0237] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0238] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0239]

[0240]

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

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

[0243] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0247] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing to obtain a silicon nitride cast film laminate material.

[0248] Wherein, when the silicon nitride cast films are stacked layer by layer, the film pieces are of the same size and fit each other completely;

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

[0250] Comparative Example 3

[0251] A silicon nitride cast film lamination process comprises the following steps:

[0252] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0253] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0254]

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

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

[0257] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0261] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and warm isostatic pressing to obtain a silicon nitride cast film laminate material.

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

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

[0264] Comparative Example 4

[0265] A silicon nitride cast film lamination process comprises the following steps:

[0266] S1, preparing silicon nitride slurry, casting, and drying to obtain a silicon nitride cast film;

[0267] Wherein, the silicon nitride slurry comprises the following components in parts by mass:

[0268]

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

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

[0271] Preferably, the binder 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 comprises: mixing silicon nitride ceramic powder, a sintering aid, a dispersant and a solvent, and then ball-milling the mixture, and then adding a plasticizer and a binder and mixing the mixture evenly to obtain the silicon nitride slurry.

[0275] S2, stacking the silicon nitride cast film layer by layer to a preset thickness (1 mm), vacuum packaging with a vacuum bag, and cold isostatic pressing;

[0276] Wherein, when the silicon nitride cast films are stacked layer by layer, the size difference between the edges of the two films is 1 mm, and there is one air hole on each of the four edges;

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

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

[0279] The process conditions of warm isostatic pressing are: temperature of 80° C., pressure of 120 MPa, and holding time of 7 min.

[0280] Performance Testing

[0281] 100 samples each prepared in Examples 1-10 and Comparative Examples 1-4 were randomly selected, and microstructure characterization tests were performed on the samples.

[0282] The test method is: the laminated samples are observed using an optical microscope to measure the microstructure and interlayer bonding of the materials. Specifically, a 100*1mm 2 The area is scanned to observe the defects in the main area and record the number of bubbles and changes in shape and structure (circular holes are recorded as bubbles, obvious stratification interfaces are recorded as stratification, and samples with both bubbles and stratification are uniformly recorded as stratification).

[0283] The microscopic morphology of the good product in Example 1 is as follows Figure 1 shown.

[0284] The microscopic morphology of the sample with bubbles in Comparative Example 1 is as follows: Figure 2 shown.

[0285] The microscopic morphology of the sample with delamination in Comparative Example 1 is as follows: Figure 3 shown.

[0286] The microscopic morphology of the sample with delamination in Comparative Example 2 is as follows: Figure 4 shown.

[0287] The microscopic morphology of the sample with delamination in Comparative Example 3 is as follows: Figure 5 shown.

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

[0289] Table 1

[0290]

[0291]

[0292] It can be seen from Table 1 that the product obtained by the silicon nitride cast film lamination process of the present invention can reduce bubbles and the yield is above 94%.

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

[0294] It can be seen from Examples 2 and 9 and Comparative Examples 1-2 that when lamination is performed without air holes and without the step of removing the vacuum bag and performing warm isostatic pressing, delamination is more likely to occur, and the product yield rate is significantly reduced. In Comparative Example 3, cold isostatic pressing is not used, but warm isostatic pressing is used directly after encapsulation, and the phenomenon of bubbles is reduced, but delamination is still likely to occur, and the product yield rate is low.

[0295] Compared with Example 9, in Comparative Example 3, the vacuum bag was not opened after cold isostatic pressing, but warm isostatic pressing was performed directly, and the probability of stratification was significantly increased, and the product yield was low. The reason is that after cold isostatic pressing, bubbles will remain between the layers, and some adhesive solvents will accumulate. If the vacuum bag is not opened and vacuumed to extract this part of the gas, the product yield will be significantly reduced.

[0296] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A silicon nitride cast film lamination process, It is characterized in that The following steps are involved: S1, preparing silicon nitride cast film; S2, stacking the silicon nitride cast film layer by layer to a preset thickness, vacuum packaging, and cold isostatic pressing; S3, removing the vacuum packaging of the material obtained in step S2, performing secondary vacuum packaging, and performing warm isostatic pressing to obtain a silicon nitride cast film laminate material.

2. The silicon nitride cast film lamination process according to claim 1, It is characterized in that In step S2, the process conditions of cold isostatic pressing are: temperature of 25±5°C and pressure of 50-80Mpa.

3. The silicon nitride cast film lamination process according to claim 1, It is characterized in that In step S3, the process conditions of warm isostatic pressing are: temperature of 70±10° C. and pressure of 80-150 MPa.

4. The silicon nitride cast film lamination process according to claim 1, It is characterized in that In the vacuum packaging or secondary vacuum packaging, the vacuum degree is -0.08Mpa to -0.1Mpa.

5. The silicon nitride cast film lamination process according to claim 1, It is characterized in that 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 drying to obtain silicon nitride cast film.

6. The silicon nitride cast film lamination process according to claim 5, It is characterized in that The silicon nitride slurry comprises the following components in parts by mass:

7. The silicon nitride cast film lamination process according to claim 6, It is characterized in that The mass ratio of the plasticizer to the binder is (0.5-0.9):

1.

8. The silicon nitride cast film lamination process according to claim 6 or 7, It is characterized in that The plasticizer is dioctyl phthalate; and the binder is polyvinyl butyral.

9. A silicon nitride cast film laminate material, It is characterized in that It is made by a silicon nitride cast film lamination process as described in any one of claims 1-8.

10. Use of the silicon nitride cast film laminate material according to claim 9 in preparing a ceramic substrate.

Images