Rare earth-glass ceramic-biological fiber synergistic low-temperature sintering LTCC raw material belt and preparation method thereof

Abstract

The invention discloses a rare earth-microcrystalline glass-bio-fiber synergistic low-temperature sintering LTCC raw material belt and a preparation method thereof, and relates to the technical field of low-temperature co-fired ceramics, the rare earth-microcrystalline glass-bio-fiber synergistic low-temperature sintering LTCC raw material belt comprises an inorganic solid phase and an organic system; wherein the inorganic solid phase is prepared from the following components in percentage by mass: 55 to 70 weight percent of Li2Mg (1-x) RxTi3O8, 25 to 43 weight percent of Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, 0.2 to 1.0 weight percent of a grain boundary pinning agent and 0.3 to 1.2 weight percent of delignified nano cellulose; the organic system comprises the following components in percentage by mass: 6-14wt% of a binder, 1-3wt% of a dispersing agent and the balance of a mixed solvent of ethanol and butyl acetate. The method has the effects that the sintering temperature is reduced to 780 DEG C, the dielectric loss is reduced by 40%, and co-firing of the silver electrode is zero in diffusion and bubble.

Description

Technical Field

[0001] This application relates to the field of low-temperature co-fired ceramics technology, and in particular to a rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape and its preparation method. Background Technology

[0002] LTCC, or Low-Temperature Co-fired Ceramic, is a technology that enables the co-sintering of ceramic and metal electrodes. This technology allows for the fabrication of ceramic substrates with precise thickness and high density, enabling the embedding of passive components within the substrate and the surface mounting of active components on the top and bottom surfaces, achieving three-dimensional integration. Currently, LTCC technology plays a crucial role in 5G millimeter-wave communication applications, including filters, antennas, and ceramic substrates. LTCC can utilize silver, gold, copper, and other relatively low-melting-point conductors as electrode materials, offering advantages such as low high-frequency transmission loss, high thermal shock resistance, and high assembly density.

[0003] In existing technologies, BaO-B2O3-ZnO-SiO2 or ZnO-B2O3-SiO2 glass is generally used as a sintering aid for LTCC raw tape. For example, Chinese patent application CN113045305A discloses an LTCC raw tape material, substrate, and preparation method, with a sintering temperature of 890-920℃. Currently, the sintering temperature is generally not less than 850℃. To reduce the energy consumption generated by sintering, rare earth oxides such as La3O3 and CeO2 are generally introduced as sintering aids. However, rare earth ions tend to segregate in the glass phase, leading to increased dielectric loss. At the same time, traditional polyacrylate dispersants leave carbon residue after high-temperature decomposition, causing blistering at the silver paste co-firing interface, which in turn affects the production cost and quality of LTCC raw tape and needs improvement. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape and its preparation method, so as to achieve the goals of low-temperature sintering, low dielectric loss, interface compatibility, and no carbon residue. The specific solution is as follows: A rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape, comprising an inorganic solid phase and an organic system; wherein: The inorganic solid phase comprises 55-70 wt% Li₂Mg₁⁻ x R x Ti3O8, 25-43wt% Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, 0.2-1.0wt% grain boundary pinning agent, and 0.3-1.2wt% delignified nanocellulose; The organic system comprises 6-14 wt% of a binder, 1-3 wt% of a dispersant, and the balance being a mixed solvent of ethanol and butyl acetate.

[0005] Preferably: in an inorganic solid phase, the Li2Mg1- x R x R for Ti3O8 is Er 3+ Yb 3+ Or Er 3+ With Yb 3+ The molar ratio is 1:1-3:1 for co-doping, and x = 0.03-0.07.

[0006] Preferably, in the inorganic solid phase, the mass percentage of Li2O in the Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2 is 20-25%, the mass percentage of Al2O3 is 15-20%, the mass percentage of B2O3 is 35-45%, the mass percentage of SiO2 is 10-18%, the mass percentage of ZnO is 3-8%, and the mass percentage of MnO2 is 0.5-2%.

[0007] Preferably, the grain boundary pinning agent is Sc2O3 nanocrystals with a D50 of 50-100 nm; the delignified nanocellulose has a diameter of 5-30 nm and an aspect ratio of 100-500.

[0008] Preferably, the Sc2O3 nanocrystals are surface-modified with citric acid, and the delignified cellulose nanofibers are carboxylated or sulfonated CNFs with a zeta potential ≤ -30mV.

[0009] Preferably, the citric acid surface modification treatment includes step ① copolymer preparation: dissolving CS-CA in a DMF aqueous solution with a volume ratio of 1:1, stirring at 60°C to obtain a 5% mass concentration CS-CA solution; then adding phosphoric anhydride and DMAP to the CS-CA solution, controlling the mass ratio of phosphoric anhydride and DMAP to CS-CA to be 1-2:0.5:10, and stirring at 80-90°C to obtain a phosphoric acid esterification solution; adding ethanol to the phosphoric acid esterification solution for precipitation, allowing it to stand and filter to obtain a precipitate, washing the precipitate with ethanol and drying at 60°C to obtain a phosphate-modified chitosan oligosaccharide-citric acid copolymer; step ② Sc2O3 nanocrystal activation: activating Sc2O3 nanocrystals... O3 nanocrystals were added to a dilute nitric acid solution, with the solid-liquid mass ratio controlled at 1:10. The mixture was stirred at 60°C for at least 2 hours, followed by washing with deionized water and drying to obtain activated Sc2O3 nanocrystals. Step ③: Coating reaction: Phosphate-modified chitosan oligosaccharide-citric acid copolymer was dissolved in an ethanol aqueous solution with a volume ratio of 3:1 to obtain a polymer solution with a mass concentration of 1%. Activated Sc2O3 nanocrystals with a mass ratio of 10:1-2 to the phosphate-modified chitosan oligosaccharide-citric acid copolymer were added to the polymer solution. After ultrasonic dispersion, the temperature was raised to 50-60°C, and the mixture was stirred for 3 hours, centrifuged with anhydrous ethanol for precipitation, washed with ethanol, and dried to obtain modified Sc2O3 nanocrystals.

[0010] Preferably, the binder is polylactic acid-co-caprolactone, the dispersant is chitosan oligosaccharide-citric acid graft copolymer, and the volume ratio of ethanol to butyl acetate in the mixed solvent is 60 / 40-70 / 30.

[0011] The second objective of this invention is to provide a method for preparing rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape, which is used to prepare the rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape as described above, comprising the following steps: Step 1: Mix the inorganic solid phase and the organic system, perform vacuum degassing and casting to obtain raw material strip blanks; Step 2: Place the raw material strips in a graphite-silicon carbide composite fixture; Step 3: Under an air or nitrogen-oxygen mixed atmosphere, control the furnace temperature to 780-820℃ and the DC electric field strength to 18-32 V·cm. -1 ; Step 4: Place the graphite-silicon carbide composite fixture into the furnace and sinter for 3-10 minutes, controlling the current density to decrease from 5 mA·cm² within 60-300 seconds. -2 Rise to 200-300 mA·cm -2 After sintering, the power is turned off and the material is cooled to obtain the finished raw material strip.

[0012] Preferably, in step 4, the cooling rate is not less than 15°C / min. -1 The temperature was cooled to 600°C at a cooling rate, and then gradually cooled to room temperature.

[0013] Preferably, the relative density of the finished raw material tape is ≥98%, and the dielectric loss tan δ is ≤1.3×10⁻⁶. -3 .

[0014] As can be seen from the above scheme, this application provides a rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape and its preparation method. This rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape and its preparation method have the following beneficial effects: 1. By leveraging the synergistic effect of a rare-earth-doped crystalline phase-microcrystalline glass transient liquid phase-biofiber three-dimensional network, combined with a preparation process based on "electro-thermal coupling flash sintering," the problem of incompatibility between low-temperature sintering and interface compatibility in traditional LTCC raw material tapes is overcome. This achieves effective control of the sintering temperature at 780-820℃ and dielectric loss tanδ ≤ 1.3 × 10⁻⁶. -3 With the goals of achieving a warpage of <50µm and a 35% reduction in energy consumption (10GHz), this method for preparing rare earth-microcrystalline glass-biofiber synergistic low-temperature sintering LTCC raw material tape has significant industrial application value. 2. By using carboxylation or sulfonation to modify delignified nanocellulose, strong electrostatic repulsion is uniformly dispersed in the inorganic solid phase. The resulting three-dimensional network structure has the effect of inhibiting the formation of micropores during the sintering process and controlling the temperature coefficient of dielectric constant within ±15ppm / ℃, effectively ensuring that the dielectric performance stability is significantly improved over a wide temperature range, i.e., from -55℃ to 125℃. 3. By activating Sc2O3 nanocrystals with dilute nitric acid and coating them with copolymers, an organic coating layer is formed on the surface of the Sc2O3 nanocrystals. This allows the phosphate groups in the organic coating layer to interact with the Sc2O3 nanocrystals. 3+ Coordination bonds are formed, and hydrogen bonds are formed between organic segments and binders and dispersants, thereby effectively solving the interfacial compatibility problem between inorganic particles and organic systems. 4. By using polylactic acid-co-caprolactone as a binder and chitosan oligosaccharide-citric acid graft copolymer as a dispersant in the organic system, both have the ability to completely decompose at a low temperature of 400℃, achieving the goal of low carbon and no carbon residue. Detailed Implementation

[0015] The technical solutions described below in conjunction with the embodiments of this application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0016] It should be mentioned that the Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2 in this embodiment of the application, as a microcrystalline glass, has the effect of generating a transient liquid phase of not less than 15 vol% within 3 minutes at a temperature of 780-820℃, and the glass transition temperature Tg is 550-620℃. Meanwhile, the prepared rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape has a single-layer thickness of 25-100 µm, a stacked layer number of 5-50 layers, and a total warpage after isostatic pressing of <50 µm.

[0017] In the preparation method of rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape, the graphite gasket in the graphite-silicon carbide composite fixture has a thickness of 0.5-2 mm and a thermal conductivity of 80-120 W·m. -1 ·K -1 This is to achieve uniform coupling between the electric field and temperature. Simultaneously, a stage is applied in the DC electric field at a rate of 2-5℃ / min. -1 The furnace temperature is finely adjusted at a certain rate to compensate for Joule heat fluctuations, ensuring that the temperature difference between the center and edge of the stack is ≤5℃.

[0018] The following will provide a detailed description of the rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape and its preparation method.

[0019] A rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape, comprising an inorganic solid phase and an organic system.

[0020] The inorganic solid phase includes 55-70 wt% Li₂Mg₁⁻ x R x Ti3O8, 25-43wt% Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, 0.2-1.0wt% grain boundary pinning agent, and 0.3-1.2wt% delignified nanocellulose; Li2Mg1- x R x R for Ti3O8 is Er 3+ Yb 3+ Or Er 3+ With Yb 3+The mixture is co-doped in a molar ratio of 1:1 to 3:1, with x = 0.03-0.07. The mass percentages of Li2O in the Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2 composition are 20-25%, Al2O3 15-20%, B2O3 35-45%, SiO2 10-18%, ZnO 3-8%, and MnO2 0.5-2%. The grain boundary pinning agent is Sc2O3 nanocrystals with a D50 of 50-100 nm; the diameter of the delignified cellulose nanocrystals is 5-30 nm, and the aspect ratio is 100-500. The Sc2O3 nanocrystals are surface-modified with citric acid, and the delignified cellulose nanocrystals are carboxylated or sulfonated CNFs with a Zeta potential ≤ -30 mV.

[0021] It should be noted that the citric acid surface modification treatment includes step ① copolymer preparation: CS-CA is dissolved in a DMF aqueous solution with a volume ratio of 1:1, and stirred at 60℃ to obtain a 5% mass concentration CS-CA solution; then phosphoric anhydride and DMAP are added to the CS-CA solution, controlling the mass ratio of phosphoric anhydride and DMAP to CS-CA to be 1-2:0.5:10, and stirred at 80-90℃ to obtain a phosphoric acid esterification solution; ethanol is added to the phosphoric acid esterification solution for precipitation, standing and filtration are performed to obtain a precipitate, the precipitate is washed with ethanol and dried at 60℃ to obtain a phosphate-modified chitosan oligosaccharide-citric acid copolymer; step ② Sc2O3 nanocrystal activation: Sc2O3 nanocrystals are activated... O3 nanocrystals were added to a dilute nitric acid solution, with the solid-liquid mass ratio controlled at 1:10. The mixture was stirred at 60°C for at least 2 hours, followed by washing with deionized water and drying to obtain activated Sc2O3 nanocrystals. Step ③: Coating reaction: Phosphate-modified chitosan oligosaccharide-citric acid copolymer was dissolved in an ethanol aqueous solution with a volume ratio of 3:1 to obtain a polymer solution with a mass concentration of 1%. Activated Sc2O3 nanocrystals with a mass ratio of 10:1-2 to the phosphate-modified chitosan oligosaccharide-citric acid copolymer were added to the polymer solution. After ultrasonic dispersion, the temperature was raised to 50-60°C, and the mixture was stirred for 3 hours, centrifuged with anhydrous ethanol for precipitation, washed with ethanol, and dried to obtain modified Sc2O3 nanocrystals.

[0022] The organic system comprises 6-14 wt% of a binder, 1-3 wt% of a dispersant, and the balance being a mixed solvent of ethanol and butyl acetate. The binder is polylactic acid-co-caprolactone, the dispersant is a chitosan oligosaccharide-citric acid graft copolymer, and the volume ratio of ethanol to butyl acetate in the mixed solvent is 60 / 40-70 / 30.

[0023] A method for preparing rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape, used to prepare the rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape as described above, includes the following steps: Step 1: Mix the inorganic solid phase and the organic system, perform vacuum degassing and casting to obtain raw material strip blanks; Step 2: Place the raw material strips in a graphite-silicon carbide composite fixture; Step 3: Under an air or nitrogen-oxygen mixed atmosphere, control the furnace temperature to 780-820℃ and the DC electric field strength to 18-32 V·cm. -1 ; Step 4: Place the graphite-silicon carbide composite fixture into the furnace and sinter for 3-10 minutes, controlling the current density to decrease from 5 mA·cm² within 60-300 seconds. -2 Rise to 200-300 mA·cm -2 After sintering, the power is turned off and the material is cooled to obtain the finished raw material strip.

[0024] In step 3, a nitrogen-oxygen mixed atmosphere is used, with the nitrogen-oxygen volume ratio controlled at 5:1. In step 4, the cooling rate is at least 15°C per minute. -1 The temperature is lowered to 600℃ at a cooling rate, and then gradually reduced to room temperature. The finished raw material tape has a relative density ≥98% and a dielectric loss tan δ ≤1.3×10⁻⁶. -3 .

[0025] Example 1 A rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape, comprising an inorganic solid phase and an organic system.

[0026] The inorganic solid phase comprises 64.6 wt% Li2Mg1-xRxTi3O8, 34 wt% Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, 0.6 wt% grain boundary pinning agent, and 0.8 wt% delignified nanocellulose.

[0027] In Li2Mg1-xRxTi3O8, R is co-doped with Er3+ and Yb3+ in a molar ratio of 1.5:1, and x = 0.05. In Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, the mass percentages of Li2O are 22%, Al2O3 is 18%, B2O3 is 40%, SiO2 is 15%, ZnO is 4%, and MnO2 is 1%. The grain boundary pinning agent is Sc2O3 nanocrystals with a D50 of 80 nm. The delignified cellulose nanocrystals have a diameter of 10 nm and an aspect ratio of 250. The Sc2O3 nanocrystals are surface-modified with citric acid, and the delignified cellulose nanocrystals are carboxylated or sulfonated CNFs with a Zeta potential ≤ -30 mV.

[0028] It should be noted that the citric acid surface modification treatment includes step ① copolymer preparation: CS-CA is dissolved in a DMF aqueous solution with a volume ratio of 1:1, and stirred at 60℃ to obtain a 5% mass concentration CS-CA solution; then phosphoric anhydride and DMAP are added to the CS-CA solution, controlling the mass ratio of phosphoric anhydride and DMAP to CS-CA to be 1:0.5:10, and stirred at 80℃ to obtain a phosphoric acid esterification solution; ethanol is added to the phosphoric acid esterification solution for precipitation, standing and filtration are performed to obtain a precipitate, and the precipitate is washed with ethanol and dried at 60℃ to obtain a phosphate-modified chitosan oligosaccharide-citric acid copolymer; step ② Sc2O3 nanocrystal activation: Sc2O3 nanocrystals are activated... Sc2O3 nanocrystals were added to a dilute nitric acid solution, with a solid-liquid mass ratio of 1:10. The mixture was stirred at 60°C for 2 hours, followed by washing with deionized water and drying to obtain activated Sc2O3 nanocrystals. Step ③: Coating reaction: Phosphate-modified chitosan oligosaccharide-citric acid copolymer was dissolved in an ethanol-water solution with a volume ratio of 3:1 to obtain a polymer solution with a mass concentration of 1%. Activated Sc2O3 nanocrystals with a mass ratio of 10:1 to the phosphate-modified chitosan oligosaccharide-citric acid copolymer were added to the polymer solution. After ultrasonic dispersion, the solution was heated to 50°C and stirred for 3 hours. After centrifugation with anhydrous ethanol and washing with ethanol, the solution was dried to obtain modified Sc2O3 nanocrystals.

[0029] The organic system comprises 10 wt% of a binder, 2 wt% of a dispersant, and the balance being a mixed solvent of ethanol and butyl acetate. The binder is polylactic acid-co-caprolactone, the dispersant is a chitosan oligosaccharide-citric acid graft copolymer, and the volume ratio of ethanol to butyl acetate in the mixed solvent is 13:7.

[0030] A method for preparing rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape, used to prepare the rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape as described above, includes the following steps: Step 1: Mix the inorganic solid phase and the organic system, perform vacuum degassing and casting to obtain raw material strip blanks; Step 2: Place 10 layers of raw material strip blanks in a graphite-silicon carbide composite fixture; Step 3: Under an air or nitrogen-oxygen mixed atmosphere, control the furnace temperature to 790℃ and the DC electric field strength to 25V•cm-1; Step 4: Place the graphite-silicon carbide composite fixture into the furnace and sinter for 4 minutes. Control the current density to increase from 5 mA•cm-2 to 220 mA•cm-2 within 120 seconds. After sintering, turn off the power and cool down to obtain the finished raw material strip.

[0031] The relative density of the obtained finished raw material strip was 98.5%, ε r =6.75, tanδ=1.1×10-3 (10 GHz), flexural strength is 215MPa, warpage is 42µm, and foaming rate at the silver paste co-fired interface is less than 0.1%.

[0032] Example 2 A rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape, comprising an inorganic solid phase and an organic system.

[0033] The inorganic solid phase comprises 64 wt% Li2Mg1-xRxTi3O8, 32 wt% Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, 0.5 wt% grain boundary pinning agent, and 1 wt% delignified nanocellulose.

[0034] In Li2Mg1₋xRxTi3O8, R is co-doped with Er3+ and Yb3+ in a molar ratio of 2.5:1, and x = 0.07. In Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, the mass percentages of Li2O are 22%, Al2O3 is 18%, B2O3 is 40%, SiO2 is 15%, ZnO is 3.5%, and MnO2 is 1.5%. The grain boundary pinning agent is Sc2O3 nanocrystals with a D50 of 80 nm. The delignified cellulose nanocrystals have a diameter of 10 nm and an aspect ratio of 250. The Sc2O3 nanocrystals are surface-modified with citric acid, and the delignified cellulose nanocrystals are carboxylated or sulfonated CNFs with a Zeta potential ≤ -30 mV.

[0035] It should be noted that the citric acid surface modification treatment includes step ① copolymer preparation: CS-CA is dissolved in a DMF aqueous solution with a volume ratio of 1:1, and stirred at 60℃ to obtain a 5% mass concentration CS-CA solution; then phosphoric anhydride and DMAP are added to the CS-CA solution, controlling the mass ratio of phosphoric anhydride and DMAP to CS-CA to be 1-2:0.5:10, and stirred at 84℃ to obtain a phosphoric acid esterification solution; ethanol is added to the phosphoric acid esterification solution for precipitation, standing and filtration are performed to obtain a precipitate, and the precipitate is washed with ethanol and dried at 60℃ to obtain a phosphate-modified chitosan oligosaccharide-citric acid copolymer; step ② Sc2O3 nanocrystal activation: Sc2O3 nanocrystals are activated... Sc2O3 nanocrystals were added to a dilute nitric acid solution, with a solid-liquid mass ratio of 1:10. The mixture was stirred at 60°C for 2 hours, followed by washing with deionized water and drying to obtain activated Sc2O3 nanocrystals. Step ③: Coating reaction: Phosphate-modified chitosan oligosaccharide-citric acid copolymer was dissolved in an ethanol-water solution with a volume ratio of 3:1 to obtain a polymer solution with a mass concentration of 1%. Activated Sc2O3 nanocrystals with a mass ratio of 10:1.5 to the phosphate-modified chitosan oligosaccharide-citric acid copolymer were added to the polymer solution. After ultrasonic dispersion, the solution was heated to 55°C and stirred for 3 hours. After centrifugation with anhydrous ethanol and washing with ethanol, the solution was dried to obtain modified Sc2O3 nanocrystals.

[0036] The organic system comprises 11 wt% of a binder, 1.8 wt% of a dispersant, and the balance being a mixed solvent of ethanol and butyl acetate. The binder is polylactic acid-co-caprolactone, the dispersant is a chitosan oligosaccharide-citric acid graft copolymer, and the volume ratio of ethanol to butyl acetate in the mixed solvent is 3:2.

[0037] A method for preparing rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape, used to prepare the rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape as described above, includes the following steps: Step 1: Mix the inorganic solid phase and the organic system, perform vacuum degassing and casting to obtain raw material strip blanks; Step 2: Place the raw material strips in a graphite-silicon carbide composite fixture; Step 3: Under an air or nitrogen-oxygen mixed atmosphere, control the furnace temperature to 800℃ and the DC electric field strength to 28V•cm-1; Step 4: Place the graphite-silicon carbide composite fixture into the furnace and sinter for 3.5 minutes. Control the current density to increase from 5 mA•cm-2 to 250 mA•cm-2 within 120 seconds. After sintering, turn off the power and cool down to obtain the finished raw material strip.

[0038] The ε of the obtained finished raw material strip r =6.9, tanδ=1.0×10-3, flexural strength is 220MPa.

[0039] Example 3 A rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape, comprising an inorganic solid phase and an organic system.

[0040] The inorganic solid phase includes 60 wt% Li2Mg1-xRxTi3O8, 38.8 wt% Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, 0.7 wt% grain boundary pinning agent, and 0.5 wt% delignified nanocellulose. In Li2Mg1-xRxTi3O8, R is co-doped with Er3+ and Yb3+ in a molar ratio of 1:1, and x = 0.04. In Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, the mass percentages of Li2O are 22%, Al2O3 is 18%, B2O3 is 40%, SiO2 is 13%, ZnO is 6%, and MnO2 is 1%. The grain boundary pinning agent is Sc2O3 nanocrystals with a D50 of 80 nm. The delignified cellulose nanocrystals have a diameter of 10 nm and an aspect ratio of 250. The Sc2O3 nanocrystals are surface-modified with citric acid, and the delignified cellulose nanocrystals are carboxylated or sulfonated CNFs with a Zeta potential ≤ -30 mV.

[0041] It should be noted that the citric acid surface modification treatment includes step ① copolymer preparation: CS-CA is dissolved in a DMF aqueous solution with a volume ratio of 1:1, and stirred at 60℃ to obtain a 5% mass concentration CS-CA solution; then phosphoric anhydride and DMAP are added to the CS-CA solution, controlling the mass ratio of phosphoric anhydride and DMAP to CS-CA to be 2:0.5:10, and stirred at 90℃ to obtain a phosphoric acid esterification solution; ethanol is added to the phosphoric acid esterification solution for precipitation, standing and filtration are performed to obtain a precipitate, and the precipitate is washed with ethanol and dried at 60℃ to obtain a phosphate-modified chitosan oligosaccharide-citric acid copolymer; step ② Sc2O3 nanocrystal activation: Sc2O3 nanocrystals are activated... Sc2O3 nanocrystals were added to a dilute nitric acid solution, with a solid-liquid mass ratio of 1:10. The mixture was stirred at 60°C for 2 hours, followed by washing with deionized water and drying to obtain activated Sc2O3 nanocrystals. Step ③: Coating reaction: Phosphate-modified chitosan oligosaccharide-citric acid copolymer was dissolved in an ethanol-water solution with a volume ratio of 3:1 to obtain a polymer solution with a mass concentration of 1%. Activated Sc2O3 nanocrystals with a mass ratio of 10:2 to the phosphate-modified chitosan oligosaccharide-citric acid copolymer were added to the polymer solution. After ultrasonic dispersion, the solution was heated to 60°C and stirred for 3 hours. After centrifugation with anhydrous ethanol and washing with ethanol, the solution was dried to obtain modified Sc2O3 nanocrystals.

[0042] The organic system comprises 12 wt% binder, 2.2 wt% dispersant, and the balance being a mixed solvent of ethanol and butyl acetate. The binder is polylactic acid-co-caprolactone, the dispersant is chitosan oligosaccharide-citric acid graft copolymer, and the volume ratio of ethanol to butyl acetate in the mixed solvent is 7 / 3.

[0043] A method for preparing rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape, used to prepare the rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape as described above, includes the following steps: Step 1: Mix the inorganic solid phase and the organic system, perform vacuum degassing and casting to obtain raw material strip blanks; Step 2: Place the raw material strips in a graphite-silicon carbide composite fixture; Step 3: Under an air or nitrogen-oxygen mixed atmosphere, control the furnace temperature to 780℃ and the DC electric field strength to 22V•cm-1; Step 4: Place the graphite-silicon carbide composite fixture into the furnace and sinter for 5 minutes. Control the current density to increase from 5 mA•cm-2 to 200 mA•cm-2 within 120 seconds. After sintering, turn off the power and cool down to obtain the finished raw material strip.

[0044] In step 4, the cooling rate is set at a rate of not less than 15°C / min to 600°C, followed by gradual cooling to room temperature. The finished raw material tape has a relative density ≥98% and a dielectric loss tan δ ≤1.3×10⁻³.

[0045] The ε of the obtained finished raw material strip r =6.7, tanδ=1.3×10-3, warpage is 38µm.

[0046] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2 in Comparative Example 1 does not contain MnO2.

[0047] The tanδ of the finished raw material strip obtained based on Comparative Example 1 is greater than 2.2 × 10⁻⁶. -3 The warpage is greater than 80µm.

[0048] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that no grain boundary pinning agent Sc2O3 nanocrystals were added in Comparative Example 2.

[0049] The tan δ of the finished raw material strip obtained based on Comparative Example 2 is greater than 2.5 × 10⁻⁶. -3 The warpage is greater than 90µm.

[0050] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the grain boundary pinning agent Sc2O3 nanocrystals in Comparative Example 3 were not subjected to citric acid surface modification treatment.

[0051] The relative density of the finished raw material tape obtained based on Comparative Example 3 is 96.2%, and the dielectric constant ε is... r =7.4, tan δ=3.0×10 -3 The flexural strength is 165 MPa, the warpage is 122 µm, and the foaming rate at the silver paste co-fired interface is 10%.

[0052] It should be noted that the dielectric properties in the embodiments and comparative examples of this application are tested according to GB / T 5594.4-2015 "Test Methods for Performance of Structural Ceramic Materials for Electronic Components Part 4: Dielectric Properties Test". The relative density is obtained using Archimedes' displacement method. Warpage is tested using a laser profilometer. The blistering rate at the co-fired interface of the silver paste is tested using scanning electron microscopy (SEM). The test methods and procedures are existing conventional techniques and will not be elaborated upon here.

[0053] This demonstrates that unmodified Sc2O3 nanocrystals exhibit poor dispersibility and weak interfacial bonding, low surface hydroxyl density, and lack a phosphate ester coating layer. Furthermore, the absence of electrostatic repulsion and steric hindrance between molecules makes them prone to agglomeration in inorganic solid phases. Simultaneously, unmodified Sc2O3 nanocrystals form void templates within the raw material tape, making it difficult for the glassy phase to fill the large pores between agglomerates during sintering, resulting in increased porosity in the final sample.

[0054] In summary, this application provides a rare-earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape and its preparation method. This method utilizes a three-dimensional network synergy between rare-earth-doped crystalline phase, microcrystalline glass transient liquid phase, and biocellulose, combined with a "flash sintering" process based on electro-thermal coupling. This overcomes the traditional problem of balancing low-temperature sintering and interface compatibility in LTCC raw material tapes, achieving effective control of the sintering temperature at 780-820℃ and dielectric loss tan δ ≤ 1.3 × 10⁻⁶. -3The goal of achieving a warpage of <50µm and a 35% reduction in energy consumption (10GHz) makes the preparation method of this rare earth-microcrystalline glass-biofiber synergistic low-temperature sintering LTCC raw material tape highly valuable for industrial application. Specifically, this rare earth-microcrystalline glass-biofiber synergistic low-temperature sintering LTCC raw material tape first utilizes carboxylated or sulfonated modified delignified nanocellulose to uniformly disperse strong electrostatic repulsion forces within the inorganic solid phase. The resulting three-dimensional network structure suppresses micropore formation during sintering and controls the dielectric constant temperature coefficient within ±15ppm / ℃, effectively ensuring significantly improved dielectric stability over a wide temperature range, from -55℃ to 125℃. Secondly, by activating Sc2O3 nanocrystals with dilute nitric acid and coating them with copolymers, an organic coating layer is formed on the surface of the Sc2O3 nanocrystals. This allows the phosphate groups in the organic coating layer to interact with the Sc2O3 nanocrystals. 3+ Coordination bonds are formed, and hydrogen bonds are formed between organic segments and binders and dispersants, effectively solving the interfacial compatibility problem between inorganic particles and organic systems. Meanwhile, polylactic acid-co-caprolactone is used as a binder and chitosan oligosaccharide-citric acid graft copolymer is used as a dispersant in the organic system; both exhibit effective and complete decomposition capabilities at a low temperature of 400℃, achieving the goal of low carbon and no carbon residue.

[0055] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.

[0056] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0057] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape, characterized in that: Including inorganic solid phases and organic systems; among which: The inorganic solid phase comprises 55-70 wt% Li₂Mg₁⁻ x R x Ti3O8, 25-43wt% Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2, 0.2-1.0wt% grain boundary pinning agent, and 0.3-1.2wt% delignified nanocellulose; The organic system comprises 6-14 wt% of a binder, 1-3 wt% of a dispersant, and the balance being a mixed solvent of ethanol and butyl acetate.

2. The rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape according to claim 1, characterized in that: In the inorganic solid phase, the Li2Mg1- x R x R for Ti3O8 is Er 3+ Yb 3+ Or Er 3+ With Yb 3+ The molar ratio is 1:1-3:1 for co-doping, and x = 0.03-0.

07.

3. The rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape according to claim 1, characterized in that: In the inorganic solid phase, the mass percentage of Li2O in the Li2O-Al2O3-B2O3-SiO2-ZnO-MnO2 is 20-25%, the mass percentage of Al2O3 is 15-20%, the mass percentage of B2O3 is 35-45%, the mass percentage of SiO2 is 10-18%, the mass percentage of ZnO is 3-8%, and the mass percentage of MnO2 is 0.5-2%.

4. The rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape according to claim 1, characterized in that: The grain boundary pinning agent is Sc2O3 nanocrystals with a D50 of 50-100 nm; the delignified nanocellulose has a diameter of 5-30 nm and an aspect ratio of 100-500.

5. The rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape according to claim 4, characterized in that: The Sc2O3 nanocrystals are surface-modified with citric acid, and the delignified cellulose nanofibers are carboxylated or sulfonated CNFs with a zeta potential ≤ -30mV.

6. The rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape according to claim 5, characterized in that: The citric acid surface modification treatment includes step ① copolymer preparation: dissolving CS-CA in a DMF aqueous solution with a volume ratio of 1:1 and stirring at 60°C to obtain a 5% mass concentration CS-CA solution; Add phosphoric anhydride and DMAP to the CS-CA solution, controlling the mass ratio of phosphoric anhydride and DMAP to CS-CA to be 1-2:0.5:10, and stir at 80-90℃ to obtain a phosphoric acid esterification solution; add ethanol to the phosphoric acid esterification solution to precipitate, let stand and filter to obtain a precipitate, wash the precipitate with ethanol and dry at 60℃ to obtain a phosphate-modified chitosan oligosaccharide-citric acid copolymer; Step ② Activation of Sc2O3 nanocrystals: add Sc2O3 nanocrystals to dilute nitric acid solution, control the solid-liquid mass ratio to be 1:10, and stir at 60℃ for at least 2... h, then washed and dried with deionized water to obtain activated Sc2O3 nanocrystals; Step ③ Coating reaction: dissolve the phosphate-modified chitosan oligosaccharide-citric acid copolymer in an ethanol aqueous solution with a volume ratio of 3:1 to obtain a polymer solution with a mass concentration of 1%; add activated Sc2O3 nanocrystals with a mass ratio of 10:1-2 to the phosphate-modified chitosan oligosaccharide-citric acid copolymer to the polymer solution, and after ultrasonic dispersion treatment, heat to 50-60℃, stir and react for 3h, centrifuge with anhydrous ethanol for precipitation and wash with ethanol, and then dry to obtain modified Sc2O3 nanocrystals.

7. The rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape according to claim 1, characterized in that: The binder is polylactic acid-co-caprolactone, the dispersant is chitosan oligosaccharide-citric acid graft copolymer, and the volume ratio of ethanol to butyl acetate in the mixed solvent is 60 / 40-70 / 30.

8. A method for preparing rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape, used to prepare the rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintered LTCC raw material tape as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Mix the inorganic solid phase and the organic system, perform vacuum degassing and casting to obtain raw material strip blanks; Step 2: Place the raw material strips in a graphite-silicon carbide composite fixture; Step 3: Under an air or nitrogen-oxygen mixed atmosphere, control the furnace temperature to 780-820℃ and the DC electric field strength to 18-32 V·cm. -1 ; Step 4: Place the graphite-silicon carbide composite fixture into the furnace and sinter for 3-10 minutes, controlling the current density to decrease from 5 mA·cm² within 60-300 seconds. -2 Rise to 200-300 mA·cm -2 After sintering, the power is turned off and the material is cooled to obtain the finished raw material strip.

9. The method for preparing a rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape according to claim 8, characterized in that: In step 4, the cooling rate is not less than 15°C / min. -1 The temperature was cooled to 600°C at a cooling rate, and then gradually cooled to room temperature.

10. The method for preparing rare earth-microcrystalline glass-biocellulose synergistic low-temperature sintering LTCC raw material tape according to claim 8, characterized in that: The finished raw material tape has a relative density ≥98% and a dielectric loss tan δ ≤1.3×10⁻⁶. -3 .