A high reflectivity multilayer ceramic substrate and a method of making the same

Abstract

This invention relates to the field of ceramic substrate technology, and proposes a high-reflectivity multilayer ceramic substrate and its preparation method. A high-reflectivity multilayer ceramic substrate comprises the following components in parts by weight: 90-100 parts alumina, 8-11 parts sintering aid, 4-6 parts plasticizer, 2-3 parts dispersant, 3-4 parts binder, 10-14 parts additives, and 60-70 parts solvent. This technical solution solves the problem of poor toughness in high-reflectivity multilayer ceramic substrates in related technologies.

Description

Technical Field

[0001] This invention relates to the field of ceramic substrate technology, specifically to a high-reflectivity multilayer ceramic substrate and its preparation method. Background Technology

[0002] In optoelectronic devices, LED packaging, and various optical systems, high-reflectivity multilayer ceramic substrates are the core materials for ensuring the luminous efficiency and stability of devices. Their performance directly affects the operating efficiency and lifespan of the entire system. Traditional high-reflectivity ceramic substrates are mostly based on alumina, but these materials always face a key bottleneck—their inherent brittleness. Traditional technologies often add sintering aids to ensure the toughness and other mechanical properties of high-reflectivity multilayer ceramic substrates. However, high-reflectivity multilayer ceramic substrates themselves lack an effective plastic deformation mechanism, and once cracks occur, they tend to propagate rapidly. The toughness of high-reflectivity multilayer ceramic substrates still cannot meet the requirements of practical applications, thus seriously affecting the reliability of devices.

[0003] In summary, developing a high-reflectivity multilayer ceramic substrate that can improve toughness is of paramount importance. Summary of the Invention

[0004] This invention proposes a high-reflectivity multilayer ceramic substrate and its preparation method, which solves the problem of poor toughness of high-reflectivity multilayer ceramic substrates in related technologies.

[0005] The technical solution of the present invention is as follows:

[0006] This invention proposes a high-reflectivity multilayer ceramic substrate, comprising the following components in parts by weight: 90-100 parts alumina, 8-11 parts sintering aid, 4-6 parts plasticizer, 2-3 parts dispersant, 3-4 parts binder, 10-14 parts additives, and 60-70 parts solvent.

[0007] The preparation method of the auxiliary agent includes the following steps:

[0008] A1. Add boron nitride to water, sonicate, filter, and dry to obtain stripped boron nitride;

[0009] A2. Add the stripped boron nitride to an alkaline solution, stir, filter, wash, and dry to obtain hydroxylated boron nitride;

[0010] A3. Add the hydroxylated boron nitride to water, add tin tetrachloride, calcium chloride, and sodium hydroxide, carry out a hydrothermal reaction, concentrate, and obtain the auxiliary agent precursor;

[0011] A4. Calcining the precursor of the additive to obtain the additive.

[0012] In this invention, when a sintering aid is added to the high-reflectivity multilayer ceramic substrate, the sintering aid can effectively reduce the sintering temperature of the high-reflectivity multilayer ceramic substrate, thereby reducing energy consumption and production costs. The sintering aid can also promote ceramic densification, reduce defects such as pores, and ensure the density and uniformity of the ceramic, thus ensuring the mechanical properties of the high-reflectivity multilayer ceramic substrate.

[0013] In the high-reflectivity multilayer ceramic substrate of the present invention, when a plasticizer is added, the plasticizer reduces defects such as cracks and delamination caused by stress concentration or insufficient fluidity, thereby ensuring the mechanical properties of the ceramic substrate and helping to improve the uniformity of the microstructure of the ceramic substrate.

[0014] In the high-reflectivity multilayer ceramic substrate of the present invention, when a dispersant is added, the role of the dispersant is to make the raw material components uniformly dispersed in the solvent, so that the raw materials can fill the mold more evenly during the molding process, and reduce the defects of the high-reflectivity multilayer ceramic substrate caused by density differences.

[0015] In the high-reflectivity multilayer ceramic substrate of the present invention, when a binder is added, the binder ensures the integrity of the high-reflectivity multilayer ceramic substrate during the molding process and reduces defects such as cracks and delamination caused by loose bonding between particles.

[0016] As a further technical solution, in step A1, the mass-to-volume ratio of boron nitride to water is 1g:10~12mL.

[0017] As a further technical solution, in step A2, the alkaline solution is sodium hydroxide with a mass concentration of 10%~15%;

[0018] The mass-to-volume ratio of the stripped boron nitride to the alkaline solution is 1g:20~30mL;

[0019] The stirring speed is 200~300 rpm, the temperature is 20~30℃, and the time is 4~5 hours.

[0020] As a further technical solution, in step A3, the mass-to-volume ratio of the hydroxylated boron nitride to water is 1g:10~12mL.

[0021] As a further technical solution, in step A3, sodium hydroxide is added to adjust the pH to 12-13.

[0022] As a further technical solution, in step A3, the temperature of the hydrothermal reaction is 200~210℃, the pressure is 3.4~3.6MPa, and the time is 14~16h.

[0023] As a further technical solution, the mass ratio of tin tetrachloride, calcium chloride and boron nitride is 4:8:15~16.

[0024] In the high-reflectivity multilayer ceramic substrate of the present invention, when the mass ratio of tin tetrachloride, calcium chloride and boron nitride is 4:8:15~16 during the preparation of the additives, the toughness of the high-reflectivity multilayer ceramic substrate is further improved.

[0025] In the high-reflectivity multilayer ceramic substrate of the present invention, during the preparation of the additives, the mass ratio of tin tetrachloride, calcium chloride and boron nitride can be 4:8:15, 4:8:15.1, 4:8:15.2, 4:8:15.3, 4:8:15.4, 4:8:15.5, 4:8:15.6, 4:8:15.7, 4:8:15.8, 4:8:15.9, or 4:8:3, preferably 4:8:16.

[0026] As a further technical solution, the power of the ultrasonic treatment is 500~600W, and the time is 1~2h.

[0027] As a further technical solution, the additive is a composite additive;

[0028] The raw materials for the composite additive include additives, coupling agents, and succinamide.

[0029] As a further technical solution, the preparation method of the composite additive includes the following steps:

[0030] B1. Add the auxiliary agent to water, add the coupling agent, stir, concentrate, and dry to obtain the pretreated auxiliary agent;

[0031] B2. Add the pretreatment agent to dimethylformamide, add succinamide, stir, concentrate, and dry to obtain the composite agent.

[0032] In this invention, a composite additive consisting of an additive, a coupling agent, and succinamide is used to prepare a high-reflectivity multilayer ceramic substrate, thereby improving the reflectivity of the multilayer ceramic substrate. This invention addresses the issue that during the preparation of the high-reflectivity multilayer ceramic substrate, the tin dioxide composite on its surface has a high surface free energy, which easily leads to additive agglomeration, thus limiting the improvement in reflectivity. Therefore, a composite additive consisting of a coupling agent and succinamide is used to reduce the surface free energy of tin dioxide, preventing additive agglomeration and improving the reflectivity of the multilayer ceramic substrate.

[0033] As a further technical solution, in step B1, the mass-to-volume ratio of the additive to water is 1g:10~15mL.

[0034] As a further technical solution, in step B2, the mass-to-volume ratio of the auxiliary agent to dimethylformamide is 1g:10~15mL.

[0035] As a further technical solution, the mass ratio of the additive, coupling agent, and succinamide in the raw materials of the composite additive is 45:2:3~4.

[0036] In the high-reflectivity multilayer ceramic substrate of the present invention, during the preparation of the composite additive, the mass ratio of the additive, coupling agent, and succinamide can be 45:2:3, 45:2:3.1, 45:2:3.2, 45:2:3.3, 45:2:3.4, 45:2:3.5, 45:2:3.6, 45:2:3.7, 45:2:3.8, 45:2:3.9, or 45:2:4, preferably 45:2:4.

[0037] As a further technical solution, the coupling agent can be any of the conventional coupling agents, such as KH-550 or KH-560, preferably KH-550.

[0038] As a further technical solution, in step B1, the stirring temperature is 30~40℃, the stirring speed is 450~500rpm, and the stirring time is 2~3h.

[0039] As a further technical solution, in step B2, the stirring temperature is 50~65℃, the stirring speed is 300~350rpm, and the stirring time is 2.5~3.5h.

[0040] As a further technical solution, the sintering aid includes one or both of yttrium oxide and cerium oxide.

[0041] In the high-reflectivity multilayer ceramic substrate of the present invention, the sintering aid can be any one or more of conventional sintering aids, and can be any one or more of magnesium oxide, titanium dioxide, lanthanum oxide, scandium oxide, yttrium oxide, and cerium oxide, preferably one or two of yttrium oxide and cerium oxide.

[0042] As a further technical solution, the plasticizer includes one or both of dibutyl phthalate and tributyl citrate.

[0043] As a further technical solution, the dispersant includes one or both of ammonium polyacrylate and triethanolamine.

[0044] As a further technical solution, the adhesive includes one or both of polyvinylpyrrolidone and polyethylene glycol.

[0045] As a further technical solution, the solvent is one or both of ethanol and propanol.

[0046] This invention also proposes a method for preparing a high-reflectivity multilayer ceramic substrate, comprising the following steps:

[0047] S1. Mix alumina, sintering aid, plasticizer, dispersant, additives, and solvent evenly, then add binder to obtain slurry;

[0048] S2. The slurry is cast and dried to obtain a blank.

[0049] S3. Drill holes in the blank material, and then perform surface printing, lamination, top and bottom conduction, cutting, sintering, and cooling to obtain the high reflectivity multilayer ceramic substrate.

[0050] The working principle and beneficial effects of this invention are as follows:

[0051] In this invention, tin tetrachloride, calcium chloride, and boron nitride are used to prepare an additive that improves the toughness of high-reflectivity multilayer ceramic substrates. This differs from existing technologies where simply adding sintering aids to the raw materials of high-reflectivity multilayer ceramic substrates results in insufficient toughness. In this invention, the boron nitride is first ultrasonically treated and then peeled off. Next, an alkaline solution is used to introduce hydroxyl groups onto the surface of the boron nitride, facilitating its bonding with precipitates in subsequent steps. Finally, a hydrothermal reaction precipitates tin hydroxide and calcium hydroxide onto the nitrogen oxides. Boron nitride with tin dioxide and calcium oxide on its surface is obtained by calcination. In the process of preparing high-reflectivity multilayer ceramic substrates, tin dioxide can catalyze the reaction of calcium oxide and alumina to form layered calcium hexaaluminate. The generated layered calcium hexaaluminate and boron nitride are bonded together through alternating soft and hard layers. When cracks occur, the layered calcium hexaaluminate ensures that the overall structure of the material does not change. Boron nitride, as a weak interface, can affect the deflection of cracks, causing cracks to deflect or delaminate along the boron nitride interface, increasing the crack propagation path, and allowing energy to be released during crack propagation. Therefore, the toughness of the high-reflectivity multilayer ceramic substrate is improved. Detailed Implementation

[0052] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0053] In the following examples and comparative examples, the particle size of alumina was 1 μm, the particle size of yttrium oxide was 1 μm, the particle size of cerium oxide was 1 μm, the particle size of tin dioxide was 500 nm, the particle size of calcium oxide was 1 μm, the boron nitride was hexagonal boron nitride with a particle size of 1 μm, the weight average molecular weight of ammonium polyacrylate was 30 million, the polyvinylpyrrolidone was PVP K15, and the polyethylene glycol was PEG-6000.

[0054] Example 1

[0055] A high-reflectivity multilayer ceramic substrate comprises the following components in parts by weight: 100 parts alumina, 11 parts yttrium oxide, 6 parts dibutyl phthalate, 3 parts ammonium polyacrylate, 4 parts polyvinylpyrrolidone, 14 parts additives, and 70 parts propanol.

[0056] The preparation method of the auxiliary agent includes the following steps:

[0057] A1. Add boron nitride to water (the mass-volume ratio of boron nitride to water is 1g:12mL), sonicate at 600W for 1h, filter, and dry to obtain stripped boron nitride.

[0058] A2. Add the stripped boron nitride to a 15% sodium hydroxide solution (the mass-volume ratio of stripped boron nitride to sodium hydroxide solution is 1g:30mL), stir at 300rpm for 4h at 30℃, filter, wash, and dry to obtain hydroxylated boron nitride.

[0059] A3. Add hydroxylated boron nitride to water (the mass-volume ratio of hydroxylated boron nitride to water is 1g:12mL), add tin tetrachloride and calcium chloride (the mass ratio of tin tetrachloride, calcium chloride and boron nitride is 4:8:18), add sodium hydroxide until the pH is 13, and hydrothermally react at 210℃ and 3.6MPa for 14h to obtain the auxiliary precursor.

[0060] A4. Calcine the precursor of the additive at 650℃ for 2 hours to obtain the additive;

[0061] A method for preparing a high-reflectivity multilayer ceramic substrate includes the following steps:

[0062] S1. Mix alumina, yttrium oxide, dibutyl phthalate, ammonium polyacrylate, additives, and propanol evenly, then add polyvinylpyrrolidone to obtain a slurry;

[0063] S2. Cast the slurry into a film, dry it, and obtain the blank material;

[0064] S3. Drill holes in the blank, then perform surface printing, lamination, top and bottom conduction, cutting, sintering at 1700℃ for 4 hours, and cooling to obtain a high-reflectivity multilayer ceramic substrate.

[0065] The material used for surface printing is tungsten paste, and the printing thickness is 15μm.

[0066] The multilayer ceramic substrate has 30 layers.

[0067] Example 2

[0068] A high-reflectivity multilayer ceramic substrate comprises the following components in parts by weight: 90 parts alumina, 8 parts cerium oxide, 4 parts tributyl citrate, 2 parts triethanolamine, 3 parts polyethylene glycol, 10 parts additives, and 60 parts ethanol.

[0069] The preparation method of the auxiliary agent includes the following steps:

[0070] A1. Add boron nitride to water (the mass-volume ratio of boron nitride to water is 1g:10mL), sonicate at 500W for 2 hours, filter, and dry to obtain stripped boron nitride.

[0071] A2. Add the stripped boron nitride to a 10% sodium hydroxide solution (the mass-volume ratio of stripped boron nitride to sodium hydroxide solution is 1g:20mL), stir at 200rpm for 5h at 20℃, filter, wash, and dry to obtain hydroxylated boron nitride.

[0072] A3. Add hydroxylated boron nitride to water (the mass-volume ratio of hydroxylated boron nitride to water is 1g:10mL), add tin tetrachloride and calcium chloride (the mass ratio of tin tetrachloride, calcium chloride and boron nitride is 4:8:17), add sodium hydroxide until the pH is 12, and hydrothermally react at 200℃ and 3.4MPa for 16h to obtain the auxiliary agent precursor.

[0073] A4. Calcine the precursor of the additive at 600℃ for 3 hours to obtain the additive;

[0074] A method for preparing a high-reflectivity multilayer ceramic substrate includes the following steps:

[0075] S1. Mix alumina, cerium oxide, tributyl citrate, triethanolamine, additives, and ethanol evenly, then add polyethylene glycol to obtain a slurry;

[0076] S2. Cast the slurry into a film, dry it, and obtain the blank material;

[0077] S3. Drill holes in the blank, then perform surface printing, lamination, top and bottom conduction, cutting, sintering at 1700℃ for 4 hours, and cooling to obtain a high-reflectivity multilayer ceramic substrate.

[0078] The material for surface printing is tungsten paste, and the printing thickness is 15μm;

[0079] The multilayer ceramic substrate has 30 layers.

[0080] Example 3

[0081] The only difference between this embodiment and Embodiment 2 is that the mass ratio of tin tetrachloride, calcium chloride, and boron nitride in this embodiment is 4:8:14.

[0082] Example 4

[0083] The only difference between this embodiment and Embodiment 2 is that the mass ratio of tin tetrachloride, calcium chloride, and boron nitride in this embodiment is 4:8:15.

[0084] Example 5

[0085] The only difference between this embodiment and Embodiment 2 is that the mass ratio of tin tetrachloride, calcium chloride, and boron nitride in this embodiment is 4:8:16.

[0086] Example 6

[0087] The only difference between this embodiment and embodiment 5 is that the additive in this embodiment is replaced with an equal mass of composite additive;

[0088] The preparation method of the composite additive includes the following steps:

[0089] A1. Add boron nitride to water (the mass-volume ratio of boron nitride to water is 1g:10mL), sonicate at 500W for 2 hours, filter, and dry to obtain stripped boron nitride.

[0090] A2. Add the stripped boron nitride to a 10% sodium hydroxide solution (the mass-volume ratio of stripped boron nitride to sodium hydroxide solution is 1g:20mL), stir at 200rpm for 5h at 20℃, filter, wash, and dry to obtain hydroxylated boron nitride.

[0091] A3. Add hydroxylated boron nitride to water (the mass-volume ratio of hydroxylated boron nitride to water is 1g:10mL), add tin tetrachloride and calcium chloride (the mass ratio of tin tetrachloride, calcium chloride and boron nitride is 4:8:16), add sodium hydroxide until the pH is 12, and hydrothermally react at 200℃ and 3.4MPa for 16h to obtain the auxiliary agent precursor.

[0092] A4. Calcine the precursor of the additive at 600℃ for 3 hours to obtain the additive;

[0093] A5. Add the auxiliary agent to water (mass-volume ratio of auxiliary agent to water is 1g:15mL), add coupling agent KH-550, stir at 500rpm for 2h at 40℃, concentrate, and dry to obtain the pretreated auxiliary agent.

[0094] A6. Add the pretreatment agent to dimethylformamide (the mass-volume ratio of agent to dimethylformamide is 1g:15mL), add succinamide (the mass ratio of agent, coupling agent KH-550, and succinamide is 45:2:4), stir at 350rpm for 2.5h at 65℃, concentrate, and dry to obtain the composite agent.

[0095] Example 7

[0096] The only difference between this embodiment and embodiment 5 is that the additive in this embodiment is replaced with an equal mass of composite additive;

[0097] The preparation method of the composite additive includes the following steps:

[0098] A1. Add boron nitride to water (the mass-volume ratio of boron nitride to water is 1g:10mL), sonicate at 500W for 2 hours, filter, and dry to obtain stripped boron nitride.

[0099] A2. Add the stripped boron nitride to a 10% sodium hydroxide solution (the mass-volume ratio of stripped boron nitride to sodium hydroxide solution is 1g:20mL), stir at 200rpm for 5h at 20℃, filter, wash, and dry to obtain hydroxylated boron nitride.

[0100] A3. Add hydroxylated boron nitride to water (the mass-volume ratio of hydroxylated boron nitride to water is 1g:10mL), add tin tetrachloride and calcium chloride (the mass ratio of tin tetrachloride, calcium chloride and boron nitride is 4:8:16), add sodium hydroxide until the pH is 12, and hydrothermally react at 200℃ and 3.4MPa for 16h to obtain the auxiliary agent precursor.

[0101] A4. Calcine the precursor of the additive at 600℃ for 3 hours to obtain the additive;

[0102] A5. Add the auxiliary agent to water (mass-volume ratio of auxiliary agent to water is 1g:10mL), add coupling agent KH-550, stir at 450rpm for 3h at 30℃, concentrate, and dry to obtain the pretreated auxiliary agent.

[0103] A6. Add the pretreatment agent to dimethylformamide (the mass-volume ratio of the agent to dimethylformamide is 1g:10mL), add succinamide (the mass ratio of the agent, coupling agent KH-550, and succinamide is 45:2:3), stir at 300rpm for 3.5h at 50℃, concentrate, and dry to obtain the composite agent.

[0104] Comparative Example 1

[0105] The only difference between this comparative example and Example 2 is that the preparation method of the additive in this comparative example includes the following steps:

[0106] Tin dioxide, calcium oxide and boron nitride in a mass ratio of 4:8:17 were mixed evenly to obtain the additive.

[0107] Comparative Example 2

[0108] The only difference between this comparative example and Example 2 is that the preparation method of the additive in this comparative example includes the following steps:

[0109] A1. Add boron nitride to water (the mass-volume ratio of boron nitride to water is 1g:10mL), sonicate at 500W for 2 hours, filter, and dry to obtain stripped boron nitride.

[0110] A2. Add the stripped boron nitride to a 10% sodium hydroxide solution (the mass-volume ratio of stripped boron nitride to sodium hydroxide solution is 1g:20mL), stir at 200rpm for 5h at 20℃, filter, wash, and dry to obtain hydroxylated boron nitride.

[0111] A3. Add hydroxylated boron nitride to water (the mass-volume ratio of hydroxylated boron nitride to water is 1g:10mL), add calcium chloride (the mass ratio of calcium chloride to boron nitride is 8:17), add sodium hydroxide until the pH is 12, and hydrothermally react at 200℃ and 3.4MPa for 16h to obtain the auxiliary agent precursor.

[0112] A4. Calcine the precursor of the additive at 600℃ for 3 hours to obtain the additive.

[0113] Comparative Example 3

[0114] The only difference between this comparative example and Example 2 is that the preparation method of the additive in this comparative example includes the following steps:

[0115] Tin dioxide and calcium oxide in a mass ratio of 1:2 are mixed evenly to obtain the additive.

[0116] Comparative Example 4

[0117] The only difference between this comparative example and Example 2 is that the preparation method of the additive in this comparative example includes the following steps:

[0118] Boron nitride was added to water (the mass-volume ratio of boron nitride to water was 1 g: 10 mL), and ultrasonic treatment was performed at a power of 500 W for 2 hours. The mixture was then filtered and dried to obtain the additive.

[0119] Comparative Example 5

[0120] The only difference between this comparative example and Example 2 is that the additive in this comparative example is replaced with an equal mass of boron nitride.

[0121] Experimental Example 1

[0122] The high-reflectivity multilayer ceramic substrates prepared in Examples 1-5 and Comparative Examples 1-5 were tested for fracture toughness according to the method in GB / T 23806-2009 "Test Method for Fracture Toughness of Fine Ceramics - Single-sided Precracked Beam (SEPB) Method". The test results are shown in Table 1.

[0123] Table 1. Fracture toughness test results

[0124]

[0125] As shown in Table 1, the fracture toughness of the high-reflectivity multilayer ceramic substrates prepared in Examples 1-5 of this invention reached 10.2 MPa·m. 1 / 2 Therefore, the present invention uses tin tetrachloride, calcium chloride and boron nitride to prepare additives, thereby improving the toughness of high reflectivity multilayer ceramic substrates.

[0126] Experiment Example 2

[0127] The reflectivity of the high-reflectivity multilayer ceramic substrates prepared in Examples 5-7 was measured using a C84-Ⅲ reflectivity meter. The test results are shown in Table 2.

[0128] Table 2 Reflectivity Test Results

[0129]

[0130] As shown in Table 2, the reflectivity of the high-reflectivity multilayer ceramic substrates prepared in Examples 6-7 of this invention reached over 98.6%. Therefore, the composite additives prepared by using additives, coupling agents and succinamide in this invention improved the reflectivity of the multilayer ceramic substrates.

[0131] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-reflectivity multilayer ceramic substrate, characterized in that, It includes the following components in parts by weight: 90-100 parts alumina, 8-11 parts sintering aid, 4-6 parts plasticizer, 2-3 parts dispersant, 3-4 parts binder, 10-14 parts additives, and 60-70 parts solvent; The preparation method of the auxiliary agent includes the following steps: A1. Add boron nitride to water, sonicate, filter, and dry to obtain stripped boron nitride; A2. Add the stripped boron nitride to an alkaline solution, stir, filter, wash, and dry to obtain hydroxylated boron nitride; A3. Add the hydroxylated boron nitride to water, add tin tetrachloride, calcium chloride, and sodium hydroxide, carry out a hydrothermal reaction, concentrate, and obtain the auxiliary agent precursor; A4. Calcining the precursor of the additive to obtain the additive; The mass ratio of tin tetrachloride, calcium chloride, and boron nitride is 4:8:15~16.

2. The high-reflectivity multilayer ceramic substrate according to claim 1, characterized in that, The ultrasonic treatment has a power of 500~600W and a duration of 1~2 hours; The calcination temperature is 600~650℃, and the time is 2~3h.

3. A high-reflectivity multilayer ceramic substrate according to any one of claims 1 to 2, characterized in that, The additive is a composite additive; The raw materials for the composite additive include additives, coupling agents, and succinamide.

4. The high-reflectivity multilayer ceramic substrate according to claim 3, characterized in that, The preparation method of the composite additive includes the following steps: B1. Add the auxiliary agent to water, add the coupling agent, stir, concentrate, and dry to obtain the pretreated auxiliary agent; B2. Add the pretreatment agent to dimethylformamide, add succinamide, stir, concentrate, and dry to obtain the composite agent.

5. A high-reflectivity multilayer ceramic substrate according to claim 4, characterized in that, In the raw materials of the composite additive, the mass ratio of the additive, coupling agent, and succinamide is 45:2:3~4.

6. A high-reflectivity multilayer ceramic substrate according to claim 4, characterized in that, In step B1, the stirring temperature is 30~40℃, the stirring speed is 450~500rpm, and the stirring time is 2~3h.

7. A high-reflectivity multilayer ceramic substrate according to claim 4, characterized in that, In step B2, the stirring temperature is 50~65℃, the stirring speed is 300~350rpm, and the stirring time is 2.5~3.5h.

8. A high-reflectivity multilayer ceramic substrate according to claim 1, characterized in that, The sintering aid includes one or both of yttrium oxide and cerium oxide; The plasticizer includes one or both of dibutyl phthalate and tributyl citrate. The dispersant includes one or both of ammonium polyacrylate and triethanolamine; The adhesive includes one or both of polyvinylpyrrolidone and polyethylene glycol; The solvent is one or both of ethanol and propanol.

9. A method for preparing a high-reflectivity multilayer ceramic substrate, used to prepare a high-reflectivity multilayer ceramic substrate as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Mix alumina, sintering aid, plasticizer, dispersant, additives, and solvent evenly, then add binder to obtain slurry; S2. The slurry is cast and dried to obtain a blank. S3. Drill holes in the blank material, and then perform surface printing, lamination, top and bottom conduction, cutting, sintering, and cooling to obtain the high reflectivity multilayer ceramic substrate.

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