A glass substrate for high heat dissipation chip packaging and a method of manufacturing the same

Abstract

The application discloses a kind of glass substrates for high-thermal-conductivity chip packaging and preparation method thereof, it is related to glass manufacturing technical field.The preparation method of glass substrate includes the steps of preparing modified nano hexagonal boron nitride, preparing modified nano magnesium-aluminum spinel, preparing base glass powder, and preparing glass substrate.Modified nano hexagonal boron nitride is prepared using raw materials including hydroxylated hexagonal boron nitride, ethanol aqueous solution, polyethylene glycol, tetraethyl orthosilicate diluent and silane coupling agent hydrolysate.Modified nano magnesium-aluminum spinel is prepared using raw materials including nano magnesium-aluminum spinel powder, anhydrous ethanol and silane coupling agent hydrolysate.Glass substrate is prepared using raw materials including base glass powder, modified nano hexagonal boron nitride, modified nano magnesium-aluminum spinel, polyvinyl butyral, dibutyl phthalate and dispersant.The glass substrate prepared by the application has excellent thermal conductivity and low dielectric loss.

Description

Technical Field

[0001] This invention relates to the field of glass manufacturing technology, specifically to a high thermal conductivity glass substrate for chip packaging and its preparation method. Background Technology

[0002] With the rapid development of 5G communication, artificial intelligence, high-power computing chips and new energy vehicle electronics, the integration and power density of chips continue to increase, which puts forward increasingly stringent requirements on the thermal conductivity and heat dissipation capabilities, thermal expansion matching, high-frequency dielectric properties, structural reliability and ultra-thin molding capabilities of packaging substrates.

[0003] Traditional organic packaging substrates suffer from low intrinsic thermal conductivity, poor thermal stability, and poor solderability, making them unsuitable for the long-term heat dissipation and service requirements of high-power chips. Alumina and aluminum nitride ceramic substrates, on the other hand, suffer from high sintering temperatures, complex structures, difficulties in ultra-thin molding, and high processing costs, failing to meet the development trend of high-density flip-chip packaging. Borosilicate glass substrates, with their excellent electrical insulation, high-frequency low dielectric properties, dimensional stability, and ultra-thin casting capabilities, have become the core development direction for high-end chip packaging substrates. However, pure glass has a low intrinsic thermal conductivity. Existing high thermal conductivity glass modification schemes often improve thermal conductivity by directly doping with high thermal conductivity inorganic fillers. These schemes generally suffer from poor compatibility between the filler and the glass matrix, uneven dispersion, significant deterioration of matrix mechanical properties and formability at high filler levels, low efficiency in building thermal conductive pathways, and deterioration of dielectric properties, severely limiting the large-scale application of glass substrates in high-power chip packaging. The prior art disclosed in CN119263635B is a low-brittle glass substrate and its preparation process. This prior art achieves low-brittleness optimization of float glass by compounding modified silica and modified titanium dioxide, and improves the mechanical properties and chemical resistance of the glass. However, the core performance design of this technical solution is out of touch with the application requirements of high-power chip packaging. The thermal conductivity of the finished product cannot meet the heat dissipation requirements of high-power chips. The alkali metal oxides introduced in the formula pose a risk of device failure due to ion migration, which does not meet the high reliability requirements of chip packaging.

[0004] In summary, although the existing technical solutions have improved certain properties of glass substrates to some extent, the following technical problems still exist: insufficient thermal conductivity and high dielectric loss. Summary of the Invention

[0005] In order to solve the above-mentioned problems in the prior art, the present invention provides a glass substrate for high thermal conductivity chip packaging and its preparation method, and achieves the following objective: to prepare a glass substrate with excellent thermal conductivity and low dielectric loss.

[0006] To achieve the above objectives, the following technical solution is adopted: A method for preparing a glass substrate for high thermal conductivity chip packaging includes the steps of preparing modified nano-hexagonal boron nitride, preparing modified nano-magnesium aluminum spinel, preparing basic glass micropowder, and obtaining the glass substrate.

[0007] The preparation of modified nano-hexagonal boron nitride involves spreading nano-hexagonal boron nitride in a corundum boat with a layer thickness ≤5mm, placing the boat in a muffle furnace, heating to 590-610℃ at a heating rate of 4-5℃ / min, and holding at that temperature for 2-2.5h. After the holding period, the mixture is allowed to cool naturally to room temperature to obtain hydroxylated hexagonal boron nitride. Hydroxylated hexagonal boron nitride was added to an ethanol-water solution and ultrasonically dispersed. Polyethylene glycol was added, and the mixture was stirred for 30-40 minutes at a speed of 200-300 rpm. The mixture was then transferred to a constant-temperature water bath reactor, stirred at 200-300 rpm, and heated to 35-40°C. The mixture was kept at this temperature for 20-30 minutes. The pH of the system was adjusted to 8.5±0.2 with ammonia, and the reaction was continued at this temperature for another 25-30 minutes. Then, tetraethyl orthosilicate dilution was added dropwise at a rate of 1-1.5 mL / min. After the addition was complete, the reaction was continued at this temperature for 4-4.5 hours. After the reaction was complete, silane coupling agent hydrolysate was added, and the mixture was heated to 60-65°C and reacted for 2-2.5 hours. The solid was then collected by centrifugation, washed 3-4 times with anhydrous ethanol, dried under vacuum, and passed through an 800-mesh sieve to obtain modified nano-hexagonal boron nitride.

[0008] Furthermore, the mass ratio of the hydroxylated hexagonal boron nitride, the ethanol aqueous solution, polyethylene glycol, the tetraethyl orthosilicate diluent, and the silane coupling agent hydrolysate is 100:(900-1100):(0.5-1):(30-40):(3-5). The ethanol aqueous solution is obtained by mixing anhydrous ethanol and ultrapure water at a volume ratio of (4.5-5):1. The tetraethyl orthosilicate diluent is obtained by dissolving tetraethyl orthosilicate in anhydrous ethanol, with a volume ratio of tetraethyl orthosilicate to anhydrous ethanol of 1:(3-3.2). The silane coupling agent hydrolysate is prepared by dissolving silane coupling agent KH560 in an ethanol-water mixture, adjusting the pH of the system to 4.5-5 with glacial acetic acid, stirring for 15-20 minutes at a speed of 100-200 rpm, and obtaining the silane coupling agent hydrolysate. The volume ratio of silane coupling agent KH560 to the ethanol-water mixture is 1:(4.5-5), and the ethanol-water mixture is obtained by mixing anhydrous ethanol and deionized water at a volume ratio of 9:1. The ultrasonic dispersion is performed at a power of 300-400 W for 30-40 minutes. The vacuum drying process is carried out at a temperature of 80-85℃ and a vacuum degree of -0.09 MPa to -0.095 MPa for 11-12 hours.

[0009] The modified nano-magnesium aluminum spinel was prepared as follows: dried nano-magnesium aluminum spinel powder was added to anhydrous ethanol and ultrasonically dispersed; then transferred to a constant temperature water bath reactor, stirred at 250-300 rpm, and heated to 60-65℃ in the water bath for 10-15 min; then silane coupling agent hydrolysate was added dropwise at a rate of 1-1.5 mL / min, and the reaction was continued at a constant temperature for 3-3.5 h after the addition was completed; after the reaction was completed, the sample was washed 2-3 times by centrifugation with anhydrous ethanol, vacuum dried, and passed through an 800-mesh sieve to obtain the modified nano-magnesium aluminum spinel.

[0010] Furthermore, the mass ratio of the nano-magnesium aluminum spinel powder, anhydrous ethanol, and silane coupling agent hydrolysate is 100:(900-1000):(4.5-6). The ultrasonic dispersion is performed at a power of 300-400W for 30-40 minutes. The vacuum drying process is carried out at a temperature of 80-85℃, a vacuum degree of -0.09MPa to -0.095MPa, and for 11-12 hours.

[0011] The preparation of basic glass micropowder involves: uniformly mixing silica, boron oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium dioxide, zirconium dioxide, phosphorus pentoxide, fluxing and clarifying agent, and cerium dioxide; then performing planetary ball milling and drying to obtain a mixture. The mixture is placed in a crucible and heated to 1450-1550℃ at a heating rate of 3-5℃ / min, and held at this temperature for 3-5 hours. After the holding period, the mixture is quenched in deionized water to obtain glass fragments. These glass fragments are then ball-milled, dried, and passed through a 2000-mesh sieve to obtain basic glass micropowder.

[0012] Furthermore, the raw materials used are proportioned as follows by weight: 40-55 parts silicon dioxide, 3-8 parts boron oxide, 15-25 parts aluminum oxide, 5-10 parts magnesium oxide, 4-8 parts zinc oxide, 1-3 parts titanium dioxide, 1-2 parts zirconium dioxide, 0.5-1 parts phosphorus pentoxide, 0.5-1 parts fluxing and clarifying agent, and 0.5-1 parts cerium dioxide. The fluxing and clarifying agent is obtained by mixing calcium oxide and barium oxide at a mass ratio of 1:(0.8-1). The planetary ball milling is performed using anhydrous ethanol as the medium, with a ball-to-material ratio of 2:1, a rotation speed of 300-350 rpm, and a milling time of 2-4 hours. The ball milling treatment is performed using anhydrous ethanol as the medium, with a ball-to-material ratio of 4:1, a rotation speed of 350-400 rpm, and a milling time of 6-10 hours. The drying process is carried out at a temperature of 80-100℃ for 6-12 hours.

[0013] The glass substrate is prepared by uniformly mixing basic glass micropowder, modified nano-hexagonal boron nitride, and modified nano-magnesium aluminum spinel to obtain a composite powder. Then, polyvinyl butyral, dibutyl phthalate, and a dispersant are added, and the mixture is ball-milled to obtain a slurry. The slurry is then cast into a film, dried in sections to obtain a green belt. Next, the film undergoes debinding, sintering and crystallization, and grinding and polishing to obtain the finished glass substrate.

[0014] Furthermore, the mass ratio of the basic glass micropowder, modified nano-hexagonal boron nitride, modified nano-magnesium aluminum spinel, polyvinyl butyral, dibutyl phthalate, and dispersant is 100:(12-18):(8-12):(6-8):(3-4):(1.5-2). The dispersant used is BYK-110. The ball milling is performed using anhydrous ethanol as the medium, with a ball-to-material ratio of 3:1, a rotation speed of 280-320 rpm, and for 8-12 hours. The casting process is carried out using a casting machine with a scraper gap of 200-300 μm and a casting speed of 0.5-1.5 m / min. The segmented drying process involves first drying at 60-65℃ for 2-2.5 hours; then drying at 80-85℃ for 2-2.5 hours; and finally drying at 100-105℃ for 1-1.5 hours. The debinding process involves heating to 200-210℃ at a rate of 1-2℃ / min and holding for 1-1.5 hours; then heating to 440-450℃ at a rate of 0.5-1℃ / min and holding for 4-5 hours. The sintering and crystallization process involves heating to 880-920℃ at a rate of 3-5℃ / min and holding for 2-4 hours; then cooling to 595-600℃ at a rate of 2-3℃ / min and allowing it to cool naturally to room temperature to obtain the substrate blank. The grinding and polishing process involves grinding and polishing both sides of the substrate blank, controlling the surface roughness Ra ≤ 0.5μm and the thickness tolerance to ±5μm.

[0015] The beneficial effects of this invention are as follows: (1) In this invention, the modified nano-hexagonal boron nitride generates a certain amount of B-OH active hydroxyl groups on the edge and surface of the nano-hexagonal boron nitride (h-BN) sheets through surface hydroxylation, which not only retains the high intrinsic thermal conductivity of h-BN, but also provides a high density of active sites for subsequent coating and grafting reactions; in the alcohol-water system catalyzed by ammonia, the silica oligomer generated by the hydrolysis of tetraethyl orthosilicate forms a nano-SiO2 coating layer on the h-BN surface through hydrogen bonding and condensation reaction, which can improve the compatibility of h-BN with the glass substrate and achieve tight interfacial bonding and element interdiffusion during sintering; the organic long chains grafted by silane coupling agent can generate a steric hindrance effect, inhibit the stacking and agglomeration of h-BN, and ensure that h-BN is uniformly dispersed in single sheets in the casting slurry and glass substrate.

[0016] (2) In this invention, the modified nano-magnesium aluminum spinel is surface-modified by a silane coupling agent, forming a functional complement to the modified h-BN. The particle size of the modified spinel precisely matches the gap size between h-BN layers, and can uniformly fill the gaps between h-BN layers and the interface between h-BN and the glass substrate. On the one hand, it connects adjacent h-BN layers, opens up the thermal conduction path in the thickness direction, and expands the two-dimensional thermal conduction network of h-BN into a three-dimensional thermal conduction path, effectively reducing the thermal resistance in the thickness direction; on the other hand, it prevents the stacking and agglomeration of h-BN layers during the casting and sintering process, maximizing the thermal conductivity of h-BN. Mg in the spinel 2+ Al 3+ It can be used as a network intermediate to enter the network structure of borosilicate glass, repair defects in the glass network, and improve the chemical stability, resistance to damp heat and high temperature of the glass; at the same time, it can be used as an auxiliary nucleating agent to regulate the crystallization behavior during the glass sintering process and avoid the formation of impurity crystals and coarse crystals.

[0017] (3) The glass substrate for high thermal conductivity chip packaging of the present invention has excellent thermal conductivity. The thermal conductivity of the prepared glass substrate is 17.2-18.5 W / m·K.

[0018] (4) The average linear thermal expansion coefficient of the high thermal conductivity glass substrate for chip packaging of the present invention can meet the matching requirements of silicon chips. The average linear thermal expansion coefficient of the prepared glass substrate is 3.2-3.8×10⁻⁶. -6 / ℃.

[0019] (5) The glass substrate for high thermal conductivity chip packaging of the present invention has low dielectric loss. The prepared glass substrate has a dielectric constant of 4.91-5.22 at 3GHz and a dielectric loss of 0.0018-0.0025 at 3GHz. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0021] Example 1 A method for preparing a glass substrate for high thermal conductivity chip packaging includes the following steps: Step 1: Preparation of modified nano-hexagonal boron nitride Nano-hexagonal boron nitride was spread evenly in a corundum ark with a layer thickness of ≤5mm. The ark was placed in a muffle furnace and heated to 590℃ at a heating rate of 4℃ / min for 2.5h. After the heating was completed, it was naturally cooled to room temperature to obtain hydroxylated hexagonal boron nitride.

[0022] Hydroxylated hexagonal boron nitride was added to an aqueous ethanol solution and ultrasonically dispersed. Polyethylene glycol was added, and the mixture was stirred for 30 min at 300 rpm. The mixture was then transferred to a constant-temperature water bath reactor, stirred at 200 rpm, and heated to 35°C. The reaction was maintained at this temperature for 30 min. The pH of the system was adjusted to 8.5 ± 0.2 with ammonia, and the reaction was continued at this temperature for another 30 min. Then, tetraethyl orthosilicate diluent was added dropwise at a rate of 1 mL / min. After the addition was complete, the reaction was continued at this temperature for 4.5 h. After the reaction was completed, silane coupling agent hydrolysate was added, and the temperature was raised to 60°C. The reaction was continued for 2.5 h. The solid was then collected by centrifugation, washed three times with anhydrous ethanol, dried under vacuum, and passed through an 800-mesh sieve to obtain modified nano-hexagonal boron nitride.

[0023] The mass ratio of the hydroxylated hexagonal boron nitride, ethanol aqueous solution, polyethylene glycol, tetraethyl orthosilicate diluent, and silane coupling agent hydrolysate is 100:900:0.5:30:3.

[0024] The ethanol-water solution is obtained by mixing anhydrous ethanol and ultrapure water at a volume ratio of 4.5:1.

[0025] The tetraethyl orthosilicate diluent is obtained by dissolving tetraethyl orthosilicate in anhydrous ethanol, with a volume ratio of tetraethyl orthosilicate to anhydrous ethanol of 1:3.

[0026] The silane coupling agent hydrolysate is prepared by dissolving silane coupling agent KH560 in an ethanol-water mixture, adjusting the pH of the system to 4.5 with glacial acetic acid, stirring for 15 minutes at a speed of 200 rpm, and obtaining the silane coupling agent hydrolysate. The volume ratio of silane coupling agent KH560 to the ethanol-water mixture is 1:4.5, and the ethanol-water mixture is obtained by mixing anhydrous ethanol and deionized water at a volume ratio of 9:1.

[0027] The ultrasonic dispersion was performed with an ultrasonic power of 300W and an ultrasonic time of 40min.

[0028] The vacuum drying process involves a temperature of 80℃, a vacuum degree of -0.09MPa, and a drying time of 12 hours.

[0029] Step 2: Preparation of modified nano-magnesium aluminum spinel Dry nano-magnesium aluminum spinel powder was added to anhydrous ethanol and ultrasonically dispersed. Then it was transferred to a constant temperature water bath reactor, stirred at 250 rpm, and heated to 60°C and reacted at a constant temperature for 15 min. Then, silane coupling agent hydrolysate was added dropwise at a rate of 1 mL / min. After the addition was complete, the reaction was continued at a constant temperature for 3.5 h. After the reaction was completed, the powder was washed twice with anhydrous ethanol by centrifugation, vacuum dried, and passed through an 800-mesh sieve to obtain modified nano-magnesium aluminum spinel.

[0030] The mass ratio of the nano-magnesium aluminum spinel powder, anhydrous ethanol, and silane coupling agent hydrolysate is 100:900:4.5.

[0031] The ultrasonic dispersion was performed with an ultrasonic power of 300W and an ultrasonic time of 40min.

[0032] The vacuum drying process involves a temperature of 80℃, a vacuum degree of -0.09MPa, and a drying time of 12 hours.

[0033] Step 3: Preparation of basic glass micropowder Silica, boron oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium dioxide, zirconium dioxide, phosphorus pentoxide, fluxing and clarifying agent, and cerium dioxide are mixed evenly, then subjected to planetary ball milling and drying to obtain a mixture.

[0034] The mixture was placed in a crucible and heated to 1450℃ at a rate of 3℃ / min, and held for 5 hours. After the holding period, it was poured into deionized water for quenching to obtain glass fragments. The glass fragments were then ball-milled, dried, and passed through a 2000-mesh sieve to obtain basic glass powder.

[0035] The raw materials used are in the following weight proportions: 40 parts silicon dioxide, 8 parts boron oxide, 15 parts aluminum oxide, 10 parts magnesium oxide, 4 parts zinc oxide, 3 parts titanium dioxide, 1 part zirconium dioxide, 1 part phosphorus pentoxide, 0.5 parts fluxing and clarifying agent, and 1 part cerium dioxide.

[0036] The fluxing and clarifying agent is obtained by mixing calcium oxide and barium oxide at a mass ratio of 1:0.8.

[0037] The planetary ball milling process involves using a planetary ball mill with anhydrous ethanol as the medium, a ball-to-material ratio of 2:1, a rotation speed of 300 rpm, and a milling time of 4 hours.

[0038] The ball milling process was carried out using anhydrous ethanol as the medium, with a ball-to-material ratio of 4:1, a rotation speed of 350 rpm, and a milling time of 10 hours.

[0039] The drying process involves drying at 80°C for 12 hours.

[0040] Step 4: Obtaining the glass substrate Basic glass micro powder, modified nano hexagonal boron nitride, and modified nano magnesium aluminum spinel are mixed evenly to obtain a composite powder. Then, polyvinyl butyral, dibutyl phthalate, and dispersant are added, and the mixture is ball-milled to obtain a slurry.

[0041] The mass ratio of the basic glass micro powder, modified nano hexagonal boron nitride, modified nano magnesium aluminum spinel, polyvinyl butyral, dibutyl phthalate, and dispersant is 100:12:8:6:3:1.5.

[0042] The dispersant used is BYK-110.

[0043] The ball milling process involved using anhydrous ethanol as the medium, a ball-to-material ratio of 3:1, a rotation speed of 280 rpm, and milling for 12 hours.

[0044] The slurry is cast and dried in sections to obtain a green strip; then the adhesive is removed, sintered and crystallized, and ground and polished to obtain the finished glass substrate.

[0045] The casting process is carried out using a casting machine with a blade gap of 200 μm and a casting speed of 1.5 m / min.

[0046] The segmented drying process involves first drying at 60°C for 2.5 hours; then drying at 80°C for 2.5 hours; and finally drying at 100°C for 1.5 hours.

[0047] The adhesive removal process involves heating to 200℃ at a rate of 1℃ / min and holding for 1.5 hours; then heating to 440℃ at a rate of 0.5℃ / min and holding for 5 hours.

[0048] The sintering crystallization process involves heating to 880°C at 3°C / min and holding for 4 hours; then cooling to 595°C at 2°C / min and allowing it to cool naturally to room temperature to obtain the substrate blank.

[0049] The grinding and polishing process involves grinding and polishing both sides of the substrate blank to control the surface roughness Ra≤0.5μm and the thickness tolerance to ±5μm.

[0050] Example 2 A method for preparing a glass substrate for high thermal conductivity chip packaging includes the following steps: Step 1: Preparation of modified nano-hexagonal boron nitride Nano-hexagonal boron nitride was spread evenly in a corundum ark with a layer thickness of ≤5mm. The ark was placed in a muffle furnace and heated to 600℃ at a heating rate of 5℃ / min for 2.5h. After the heating was completed, it was naturally cooled to room temperature to obtain hydroxylated hexagonal boron nitride.

[0051] Hydroxylated hexagonal boron nitride was added to an aqueous ethanol solution and ultrasonically dispersed. Polyethylene glycol was added, and the mixture was stirred for 35 min at 300 rpm. The mixture was then transferred to a constant-temperature water bath reactor, stirred at 300 rpm, and heated to 40°C. The reaction was maintained at this temperature for 25 min. The pH of the system was adjusted to 8.5 ± 0.2 with ammonia, and the reaction was continued at this temperature for another 30 min. Then, tetraethyl orthosilicate diluent was added dropwise at a rate of 1.5 mL / min. After the addition was complete, the reaction was continued at this temperature for 4.5 h. After the reaction was completed, silane coupling agent hydrolysate was added, and the temperature was raised to 65°C. The reaction was continued for 2.5 h. The solid was then collected by centrifugation, washed four times with anhydrous ethanol, dried under vacuum, and passed through an 800-mesh sieve to obtain modified nano-hexagonal boron nitride.

[0052] The mass ratio of the hydroxylated hexagonal boron nitride, ethanol aqueous solution, polyethylene glycol, tetraethyl orthosilicate diluent, and silane coupling agent hydrolysate is 100:1000:0.8:35:4.

[0053] The ethanol-water solution is obtained by mixing anhydrous ethanol and ultrapure water at a volume ratio of 5:1.

[0054] The tetraethyl orthosilicate diluent is obtained by dissolving tetraethyl orthosilicate in anhydrous ethanol, with a volume ratio of tetraethyl orthosilicate to anhydrous ethanol of 1:3.

[0055] The silane coupling agent hydrolysate is prepared by dissolving silane coupling agent KH560 in an ethanol-water mixture, adjusting the pH of the system to 4.8 with glacial acetic acid, stirring for 20 minutes at a speed of 200 rpm, and obtaining the silane coupling agent hydrolysate. The volume ratio of silane coupling agent KH560 to the ethanol-water mixture is 1:4.8, and the ethanol-water mixture is obtained by mixing anhydrous ethanol and deionized water at a volume ratio of 9:1.

[0056] The ultrasonic dispersion was performed with an ultrasonic power of 400W and an ultrasonic time of 35min.

[0057] The vacuum drying process involves a temperature of 85°C, a vacuum degree of -0.095 MPa, and a drying time of 11 hours.

[0058] Step 2: Preparation of modified nano-magnesium aluminum spinel Dry nano-magnesium aluminum spinel powder was added to anhydrous ethanol and ultrasonically dispersed. Then it was transferred to a constant temperature water bath reactor, stirred at 300 rpm, and heated to 65°C and reacted at a constant temperature for 15 min. Then, silane coupling agent hydrolysate was added dropwise at a rate of 1.5 mL / min. After the addition was complete, the reaction was continued at a constant temperature for 3 h. After the reaction was completed, the powder was washed three times by centrifugation with anhydrous ethanol, vacuum dried, and passed through an 800-mesh sieve to obtain modified nano-magnesium aluminum spinel.

[0059] The mass ratio of the nano-magnesium aluminum spinel powder, anhydrous ethanol, and silane coupling agent hydrolysate is 100:950:5.

[0060] The ultrasonic dispersion was performed with an ultrasonic power of 400W and an ultrasonic time of 35min.

[0061] The vacuum drying process involves a temperature of 85°C, a vacuum degree of -0.095 MPa, and a drying time of 11 hours.

[0062] Step 3: Preparation of basic glass micropowder Silica, boron oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium dioxide, zirconium dioxide, phosphorus pentoxide, fluxing and clarifying agent, and cerium dioxide are mixed evenly, then subjected to planetary ball milling and drying to obtain a mixture.

[0063] The mixture was placed in a crucible and heated to 1500℃ at a rate of 4℃ / min, and held for 4 hours. After the holding period, it was poured into deionized water for quenching to obtain glass fragments. The glass fragments were then ball-milled, dried, and passed through a 2000-mesh sieve to obtain basic glass powder.

[0064] The raw materials used are in the following weight proportions: 50 parts silicon dioxide, 6 parts boron oxide, 20 parts aluminum oxide, 8 parts magnesium oxide, 6 parts zinc oxide, 2 parts titanium dioxide, 1.5 parts zirconium dioxide, 0.8 parts phosphorus pentoxide, 0.8 parts fluxing and clarifying agent, and 0.8 parts cerium dioxide.

[0065] The fluxing and clarifying agent is obtained by mixing calcium oxide and barium oxide at a mass ratio of 1:0.9.

[0066] The planetary ball milling process involves using a planetary ball mill with anhydrous ethanol as the medium, a ball-to-material ratio of 2:1, a rotation speed of 300 rpm, and a milling time of 3 hours.

[0067] The ball milling process was carried out using anhydrous ethanol as the medium, with a ball-to-material ratio of 4:1, a rotation speed of 400 rpm, and a milling time of 8 hours.

[0068] The drying process involves drying at 90°C for 9 hours.

[0069] Step 4: Obtaining the glass substrate Basic glass micro powder, modified nano hexagonal boron nitride, and modified nano magnesium aluminum spinel are mixed evenly to obtain a composite powder. Then, polyvinyl butyral, dibutyl phthalate, and dispersant are added, and the mixture is ball-milled to obtain a slurry.

[0070] The mass ratio of the basic glass micro powder, modified nano hexagonal boron nitride, modified nano magnesium aluminum spinel, polyvinyl butyral, dibutyl phthalate, and dispersant is 100:15:10:7:3.5:1.8.

[0071] The dispersant used is BYK-110.

[0072] The ball milling process involved using anhydrous ethanol as the medium, a ball-to-material ratio of 3:1, a rotation speed of 300 rpm, and milling for 10 hours.

[0073] The slurry is cast and dried in sections to obtain a green strip; then the adhesive is removed, sintered and crystallized, and ground and polished to obtain the finished glass substrate.

[0074] The casting process is carried out using a casting machine with a blade gap of 250 μm and a casting speed of 1 m / min.

[0075] The segmented drying process involves first drying at 65°C for 2.5 hours; then drying at 85°C for 2.5 hours; and finally drying at 105°C for 1.5 hours.

[0076] The adhesive removal process involves heating to 205°C at a rate of 2°C / min and holding for 1.5 hours; then heating to 445°C at a rate of 1°C / min and holding for 4.5 hours.

[0077] The sintering crystallization process involves heating to 900°C at a rate of 4°C / min and holding for 3 hours; then cooling to 600°C at a rate of 3°C / min and allowing it to cool naturally to room temperature to obtain a substrate blank.

[0078] The grinding and polishing process involves grinding and polishing both sides of the substrate blank to control the surface roughness Ra≤0.5μm and the thickness tolerance to ±5μm.

[0079] Example 3 A method for preparing a glass substrate for high thermal conductivity chip packaging includes the following steps: Step 1: Preparation of modified nano-hexagonal boron nitride Nano-hexagonal boron nitride was spread evenly in a corundum ark with a layer thickness of ≤5mm. The ark was placed in a muffle furnace and heated to 610℃ at a heating rate of 5℃ / min for 2 hours. After the heating was completed, it was naturally cooled to room temperature to obtain hydroxylated hexagonal boron nitride.

[0080] Hydroxylated hexagonal boron nitride was added to an aqueous ethanol solution and ultrasonically dispersed. Polyethylene glycol was added, and the mixture was stirred for 40 min at 200 rpm. The mixture was then transferred to a constant-temperature water bath reactor, stirred at 300 rpm, and heated to 40°C. The reaction was maintained at this temperature for 20 min. The pH of the system was adjusted to 8.5 ± 0.2 with ammonia, and the reaction was continued at this temperature for another 25 min. Then, tetraethyl orthosilicate diluent was added dropwise at a rate of 1.5 mL / min. After the addition was complete, the reaction was continued at this temperature for 4 h. After the reaction was completed, silane coupling agent hydrolysate was added, and the temperature was raised to 65°C. The reaction was continued for 2 h. The solid was then collected by centrifugation, washed four times with anhydrous ethanol, dried under vacuum, and passed through an 800-mesh sieve to obtain modified nano-hexagonal boron nitride.

[0081] The mass ratio of the hydroxylated hexagonal boron nitride, aqueous ethanol solution, polyethylene glycol, tetraethyl orthosilicate diluent, and silane coupling agent hydrolysate is 100:1100:1:40:5.

[0082] The ethanol-water solution is obtained by mixing anhydrous ethanol and ultrapure water at a volume ratio of 5:1.

[0083] The tetraethyl orthosilicate diluent is obtained by dissolving tetraethyl orthosilicate in anhydrous ethanol, with a volume ratio of tetraethyl orthosilicate to anhydrous ethanol of 1:3.2.

[0084] The silane coupling agent hydrolysate is prepared by dissolving silane coupling agent KH560 in an ethanol-water mixture, adjusting the pH of the system to 5 with glacial acetic acid, stirring for 20 minutes at a speed of 100 rpm, and obtaining the silane coupling agent hydrolysate. The volume ratio of silane coupling agent KH560 to the ethanol-water mixture is 1:5, and the ethanol-water mixture is obtained by mixing anhydrous ethanol and deionized water at a volume ratio of 9:1.

[0085] The ultrasonic dispersion was performed with an ultrasonic power of 400W and an ultrasonic time of 30min.

[0086] The vacuum drying process involves a temperature of 85°C, a vacuum degree of -0.095 MPa, and a drying time of 11 hours.

[0087] Step 2: Preparation of modified nano-magnesium aluminum spinel Dry nano-magnesium aluminum spinel powder was added to anhydrous ethanol and ultrasonically dispersed. Then it was transferred to a constant temperature water bath reactor, stirred at 300 rpm, and heated to 65°C and reacted at a constant temperature for 10 min. Then, silane coupling agent hydrolysate was added dropwise at a rate of 1.5 mL / min. After the addition was complete, the reaction was continued at a constant temperature for 3 h. After the reaction was completed, the powder was washed three times by centrifugation with anhydrous ethanol, vacuum dried, and passed through an 800-mesh sieve to obtain modified nano-magnesium aluminum spinel.

[0088] The mass ratio of the nano-magnesium aluminum spinel powder, anhydrous ethanol, and silane coupling agent hydrolysate is 100:1000:6.

[0089] The ultrasonic dispersion was performed with an ultrasonic power of 400W and an ultrasonic time of 30min.

[0090] The vacuum drying process involves a temperature of 85°C, a vacuum degree of -0.095 MPa, and a drying time of 11 hours.

[0091] Step 3: Preparation of basic glass micropowder Silica, boron oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium dioxide, zirconium dioxide, phosphorus pentoxide, fluxing and clarifying agent, and cerium dioxide are mixed evenly, then subjected to planetary ball milling and drying to obtain a mixture.

[0092] The mixture was placed in a crucible and heated to 1550℃ at a heating rate of 5℃ / min for 3 hours. After the heating was completed, it was poured into deionized water for quenching to obtain glass fragments. The glass fragments were ball-milled, dried, and passed through a 2000-mesh sieve to obtain basic glass powder.

[0093] The raw materials used are in the following weight proportions: 55 parts silicon dioxide, 3 parts boron oxide, 25 parts aluminum oxide, 5 parts magnesium oxide, 8 parts zinc oxide, 1 part titanium dioxide, 2 parts zirconium dioxide, 0.5 parts phosphorus pentoxide, 1 part fluxing and clarifying agent, and 0.5 parts cerium dioxide.

[0094] The fluxing and clarifying agent is obtained by mixing calcium oxide and barium oxide in a mass ratio of 1:1.

[0095] The planetary ball milling process involves using a planetary ball mill with anhydrous ethanol as the medium, a ball-to-material ratio of 2:1, a rotation speed of 350 rpm, and a milling time of 2 hours.

[0096] The ball milling process was carried out using anhydrous ethanol as the medium, with a ball-to-material ratio of 4:1, a rotation speed of 400 rpm, and a milling time of 6 hours.

[0097] The drying process involves drying at 100℃ for 6 hours.

[0098] Step 4: Obtaining the glass substrate Basic glass micro powder, modified nano hexagonal boron nitride, and modified nano magnesium aluminum spinel are mixed evenly to obtain a composite powder. Then, polyvinyl butyral, dibutyl phthalate, and dispersant are added, and the mixture is ball-milled to obtain a slurry.

[0099] The mass ratio of the basic glass micro powder, modified nano hexagonal boron nitride, modified nano magnesium aluminum spinel, polyvinyl butyral, dibutyl phthalate, and dispersant is 100:18:12:8:4:2.

[0100] The dispersant used is BYK-110.

[0101] The ball milling process involved using anhydrous ethanol as the medium, a ball-to-material ratio of 3:1, a rotation speed of 320 rpm, and milling for 8 hours.

[0102] The slurry is cast and dried in sections to obtain a green strip; then the adhesive is removed, sintered and crystallized, and ground and polished to obtain the finished glass substrate.

[0103] The casting process is carried out using a casting machine with a blade gap of 300 μm and a casting speed of 0.5 m / min.

[0104] The segmented drying process involves first drying at 65°C for 2 hours; then drying at 85°C for 2 hours; and finally drying at 105°C for 1 hour.

[0105] The adhesive removal process involves heating to 210°C at a rate of 2°C / min and holding for 1 hour; then heating to 450°C at a rate of 1°C / min and holding for 4 hours.

[0106] The sintering crystallization process involves heating to 920°C at 5°C / min and holding for 2 hours; then cooling to 600°C at 3°C / min and allowing it to cool naturally to room temperature to obtain the substrate blank.

[0107] The grinding and polishing process involves grinding and polishing both sides of the substrate blank to control the surface roughness Ra≤0.5μm and the thickness tolerance to ±5μm.

[0108] Comparative Example 1 A method for preparing a glass substrate for high thermal conductivity chip packaging includes the following steps: Step 1: Preparation of modified nano-magnesium aluminum spinel This step is the same as the "Preparation of Modified Nano-Magnesium Aluminum Spinel" step in Example 2.

[0109] Step 2: Preparation of basic glass micropowder This step is the same as the "Preparation of basic glass micropowder" step in Example 2.

[0110] Step 3: Obtaining the glass substrate The modified nano-hexagonal boron nitride was replaced with nano-hexagonal boron nitride, and the remaining operations were the same as the "preparation of glass substrate" steps in Example 2.

[0111] Comparative Example 2 A method for preparing a glass substrate for high thermal conductivity chip packaging includes the following steps: Step 1: Preparation of modified nano-hexagonal boron nitride This step is the same as the "Preparation of Modified Nano-Hexagonal Boron Nitride" step in Example 2.

[0112] Step 2: Preparation of basic glass micropowder This step is the same as the "Preparation of basic glass micropowder" step in Example 2.

[0113] Step 3: Obtaining the glass substrate The modified nano-magnesium aluminum spinel was removed from the list, and the remaining operations were the same as the "preparation of glass substrate" steps in Example 2.

[0114] Example 4 Performance Testing (a) Thermal conductivity tests were conducted on the glass substrates prepared in Examples 1-3 and Comparative Examples 1-2. The thermal conductivity was tested according to the test method specified in GB / T38712-2020. The specific test results are shown in Table 1.

[0115] Table 1 As shown in Table 1, the thermal conductivity of the glass substrates prepared in Examples 1-3 is 17.2-18.5 W / m·K, which proves that the glass substrates prepared in this invention have excellent thermal conductivity.

[0116] (ii) The average linear thermal expansion coefficient of the glass substrates prepared in Examples 1-3 and Comparative Examples 1-2 was tested. The average linear thermal expansion coefficient of the glass substrates was tested according to the test method specified in GB / T16920-2015. The specific test results are shown in Table 2.

[0117] Table 2 As shown in Table 2, the average linear thermal expansion coefficient of the glass substrates prepared in Examples 1-3 is 3.2-3.8 × 10⁻⁶. -6 The coefficient of thermal expansion (C / ℃) is close to that of the average linear thermal expansion coefficient of silicon chips. This demonstrates that the average linear thermal expansion coefficient of the glass substrate prepared in this invention can meet the matching requirements of silicon chips.

[0118] (III) Dielectric properties of the glass substrates prepared in Examples 1-3 and Comparative Examples 1-2 were tested. Dielectric constant and dielectric loss were tested using an impedance analyzer according to the test methods specified in GB / T1409-2006. Specific test results are shown in Table 3.

[0119] Table 3 As shown in Table 3, the glass substrates prepared in Examples 1-3 have a dielectric constant of 4.91-5.22 and a dielectric loss of 0.0018-0.0025 at 3 GHz. This demonstrates that the chip packaging glass substrate prepared in this invention has low dielectric loss.

[0120] The specific parameters of the raw materials used in this invention are as follows: The nano-hexagonal boron nitride is a two-dimensional plate-like hexagonal phase boron nitride with an average lateral plate diameter (D50) of 200-400 nm, a plate thickness of 15-30 nm, and a specific surface area of ​​20-30 m². 2 / g.

[0121] The particle size of the nano-magnesium aluminum spinel powder is 30-50 nm.

[0122] Obviously, there are many other possible implementation methods under the concept of this invention. It should be stated here that any changes made under the inventive concept of this invention will fall within the protection scope of this invention.

Claims

1. A method for preparing a glass substrate for high heat-dissipating chip packaging, characterized by: The process includes the steps of preparing modified nano-hexagonal boron nitride, preparing modified nano-magnesium aluminum spinel, preparing basic glass micropowder, and obtaining a glass substrate. The preparation of modified nano-hexagonal boron nitride is as follows: Nano-hexagonal boron nitride is placed in a muffle furnace, heated, and held at that temperature; then cooled to obtain hydroxylated hexagonal boron nitride; the hydroxylated hexagonal boron nitride is added to an ethanol-water solution and ultrasonically dispersed; polyethylene glycol is added and stirred; then transferred to a constant temperature water bath reactor, stirred, heated in the water bath, and reacted at a constant temperature, adjusting the pH value of the system, and continuing the reaction at a constant temperature; then tetraethyl orthosilicate dilution is added dropwise, and the reaction continues at a constant temperature; silane coupling agent hydrolysate is added, heated, and reacted; then centrifuged, washed, vacuum dried, and sieved to obtain modified nano-hexagonal boron nitride; The modified nano-magnesium aluminum spinel was prepared by adding dried nano-magnesium aluminum spinel powder into anhydrous ethanol and dispersing it by ultrasonication. Then, the mixture was transferred to a constant-temperature water bath reactor, stirred, heated in the water bath, and reacted at a constant temperature. Then, silane coupling agent hydrolysate was added dropwise, and the reaction was continued at a constant temperature. After washing, vacuum drying, and sieving, modified nano-magnesium aluminum spinel was obtained. The preparation of the basic glass micro powder uses raw materials including silicon dioxide, boron oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium dioxide, zirconium dioxide, phosphorus pentoxide, fluxing and clarifying agent, and cerium dioxide. The glass substrate obtained is made from raw materials including basic glass micro powder, modified nano hexagonal boron nitride, modified nano magnesium aluminum spinel, polyvinyl butyral, dibutyl phthalate, and dispersant.

2. The method for preparing a high thermal conductivity chip packaging glass substrate according to claim 1, characterized in that: In the step of preparing modified nano-hexagonal boron nitride, the mass ratio of hydroxylated hexagonal boron nitride, aqueous ethanol solution, polyethylene glycol, tetraethyl orthosilicate diluent, and silane coupling agent hydrolysate is 100:(900-1100):(0.5-1):(30-40):(3-5).

3. The method for preparing a high thermal conductivity chip packaging glass substrate according to claim 1, characterized in that: The ethanol-water solution is obtained by mixing anhydrous ethanol and ultrapure water at a volume ratio of (4.5-5):1; the tetraethyl orthosilicate diluent is obtained by dissolving tetraethyl orthosilicate in anhydrous ethanol, with a volume ratio of tetraethyl orthosilicate to anhydrous ethanol of 1:(3-3.2).

4. The method for preparing a high thermal conductivity chip packaging glass substrate according to claim 1, characterized in that: The silane coupling agent hydrolysate is prepared by dissolving silane coupling agent KH560 in an ethanol-water mixture, adjusting the pH of the system to 4.5-5 with glacial acetic acid, stirring for 15-20 minutes at a speed of 100-200 rpm, and obtaining the silane coupling agent hydrolysate. The volume ratio of silane coupling agent KH560 to the ethanol-water mixture is 1:(4.5-5), and the ethanol-water mixture is obtained by mixing anhydrous ethanol and deionized water at a volume ratio of 9:

1.

5. The method for preparing a high thermal conductivity chip packaging glass substrate according to claim 1, characterized in that: In the step of preparing modified nano-magnesium aluminum spinel, the mass ratio of nano-magnesium aluminum spinel powder, anhydrous ethanol, and silane coupling agent hydrolysate is 100:(900-1000):(4.5-6).

6. The method for preparing a high thermal conductivity chip packaging glass substrate according to claim 1, characterized in that: The preparation of basic glass micro powder involves: uniformly mixing silicon dioxide, boron oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium dioxide, zirconium dioxide, phosphorus pentoxide, fluxing clarifying agent, and cerium dioxide; performing planetary ball milling and drying to obtain a mixture; placing the mixture in a crucible, heating and holding it at that temperature; then quenching, ball milling, drying, and sieving to obtain basic glass micro powder. The glass substrate is prepared by: mixing basic glass micro powder, modified nano-hexagonal boron nitride, and modified nano-magnesium aluminum spinel evenly to obtain a composite powder; then adding polyvinyl butyral, dibutyl phthalate, and a dispersant, and ball milling to obtain a slurry; casting the slurry into a film, drying it in sections to obtain a green strip; then performing a debinding process, sintering and crystallization, grinding and polishing to obtain the finished glass substrate.

7. The method for preparing a high thermal conductivity chip packaging glass substrate according to claim 6, characterized in that: In the step of preparing basic glass micro powder, the raw materials used are in the following weight ratio: 40-55 parts silicon dioxide, 3-8 parts boron oxide, 15-25 parts aluminum oxide, 5-10 parts magnesium oxide, 4-8 parts zinc oxide, 1-3 parts titanium dioxide, 1-2 parts zirconium dioxide, 0.5-1 parts phosphorus pentoxide, 0.5-1 parts fluxing and clarifying agent, and 0.5-1 parts cerium dioxide; the fluxing and clarifying agent is obtained by mixing calcium oxide and barium oxide in a mass ratio of 1:(0.8-1).

8. The method for preparing a high thermal conductivity chip packaging glass substrate according to claim 6, characterized in that: In the step of preparing basic glass micro powder, planetary ball milling is carried out using a planetary ball mill with anhydrous ethanol as the medium, a ball-to-material ratio of 2:1, a rotation speed of 300-350 rpm, and a milling time of 2-4 hours; ball milling treatment is carried out using anhydrous ethanol as the medium with a ball-to-material ratio of 4:1, a rotation speed of 350-400 rpm, and a milling time of 6-10 hours.

9. The method for preparing a glass substrate for high thermal conductivity chip packaging according to claim 6, characterized in that: The mass ratio of the basic glass micro powder, modified nano hexagonal boron nitride, modified nano magnesium aluminum spinel, polyvinyl butyral, dibutyl phthalate, and dispersant is 100:(12-18):(8-12):(6-8):(3-4):(1.5-2).

10. The method for preparing a high thermal conductivity chip packaging glass substrate according to claim 6, characterized in that: The debinding process involves heating to 200-210℃ at a rate of 1-2℃ / min and holding for 1-1.5 hours; then heating to 440-450℃ at a rate of 0.5-1℃ / min and holding for 4-5 hours. The sintering and crystallization process involves heating to 880-920℃ at a rate of 3-5℃ / min and holding for 2-4 hours; then cooling to 595-600℃ at a rate of 2-3℃ / min and allowing it to cool naturally to room temperature to obtain the substrate blank.

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