A low dielectric loss multi-layer ceramic substrate and its preparation method

Abstract

The present invention relates to the technical field of ceramic substrates, and provides a low dielectric loss multi-layer ceramic substrate and a preparation method thereof. A low dielectric loss multi-layer ceramic substrate comprises the following raw materials in parts by weight: 90-100 parts of alumina, 1-3 parts of plasticizer, 3-5 parts of sintering aid, 6-10 parts of binder, 1-3 parts of dispersant, and 50-60 parts of water. The alumina is composed of first alumina and second alumina, and the first alumina and the second alumina have different morphologies. Through the above technical solution, the problem of high dielectric loss of multi-layer ceramic substrates in the related art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic substrates, and specifically, to a low dielectric loss multi-layer ceramic substrate and a preparation method thereof. Background Art

[0002] A multi-layer ceramic substrate is a new type of electronic packaging material formed by printing, laminating, and sintering multiple ceramic wafers. Conductive circuits, vias and other structures are usually printed on these ceramic wafers to achieve electrical connection and signal transmission between electronic components. Due to its excellent mechanical properties, high insulation, and good thermal stability, the multi-layer ceramic substrate is widely used in the electronic field.

[0003] Currently, the research on multi-layer ceramic substrates mainly focuses on improving their comprehensive performance. Researchers continuously explore new material systems and optimize preparation processes to achieve higher wiring density, better heat dissipation performance, and stronger mechanical reliability, etc. However, there are still many problems to be solved in the key performance index of dielectric loss.

[0004] Dielectric loss refers to the energy loss that occurs when an electric dielectric converts electrical energy into heat energy under the action of an alternating electric field due to the hysteresis effects of dielectric conductance and dielectric polarization. For multi-layer ceramic substrates, high dielectric loss will cause a series of serious hazards. On the one hand, excessive electrical energy is converted into heat energy, resulting in an increase in the temperature of the substrate, which not only affects the normal working performance of electronic components, but also may accelerate the aging of components and shorten the service life of the equipment in the long term due to long-term high temperature. On the other hand, high dielectric loss will cause signal attenuation and distortion during transmission, reducing the accuracy and stability of signal transmission. Especially in high-frequency circuits, this problem is more prominent, seriously restricting the effective transmission of high-speed and large-capacity data.

[0005] In contrast, a multi-layer ceramic substrate with low dielectric loss has significant advantages. It can effectively reduce the loss of electrical energy converted into heat energy, reduce the heat generation of the substrate, help maintain the temperature stability of the working environment of electronic components, and improve the reliability and durability of the system. At the same time, low dielectric loss can greatly reduce the attenuation and distortion during signal transmission, ensure high-quality signal transmission, meet the requirements of modern electronic devices for high-speed and high-frequency signal processing, and lay a foundation for the realization of more advanced electronic technology applications. Therefore, it is necessary to develop a multi-layer ceramic substrate with low dielectric loss. Summary of the Invention

[0006] The present invention provides a low dielectric loss multi-layer ceramic substrate and a preparation method thereof, which solves the problem of high dielectric loss of multi-layer ceramic substrates in related technologies.

[0007] The technical solution of the present invention is as follows: The present invention provides a low dielectric loss multi-layer ceramic substrate, which comprises the following raw materials in parts by weight: 90-100 parts of alumina, 1-3 parts of plasticizer, 3-5 parts of sintering aid, 6-10 parts of binder, 1-3 parts of dispersant, and 50-60 parts of water. The alumina is composed of first alumina and second alumina, and the first alumina and the second alumina have different morphologies.

[0008] As a further technical solution, the first alumina is spherical alumina, the second alumina is flaky alumina, and the mass ratio of the first alumina to the second alumina is 2-3:1.

[0009] In the present invention, spherical alumina and flaky alumina are used in combination. Spherical alumina has good fluidity and filling properties, and can be closely packed in the matrix during the preparation of the multi-layer ceramic substrate. The interlayer structure of flaky alumina can play a role similar to a barrier, preventing excessive migration of charges and the development of polarization. When an electric field is applied, flaky alumina can limit the movement of charges between layers, reduce the energy loss during the process of charge accumulation and release, and by coordinating the mass ratio of the two, the synergistic effect of the two is exerted to further reduce the dielectric loss of the multi-layer ceramic substrate.

[0010] As a further technical solution, the average particle size of the first alumina is 3-5 μm, and the average particle size of the second alumina is 3 nm.

[0011] In the present invention, the spherical alumina with a particle size of 3-5 μm has a relatively large particle size and can build a basic framework structure, while the flaky alumina with a particle size of 3 nm has an extremely small particle size and can be filled in the gaps between the spherical alumina to form an extremely tight and orderly microstructure. This structure greatly reduces internal pores and defects, and pores and defects are the key factors causing electric field distortion and increasing dielectric loss. The tight and orderly structure makes the electric field distribution more uniform and further reduces the dielectric loss.

[0012] As a further technical solution, the second alumina is second alumina compounded with hydroxy-methoxybenzaldehyde compounds.

[0013] As a further technical solution, the hydroxy-methoxybenzaldehyde compounds include one or more of 4-hydroxy-2-methoxybenzaldehyde, 2-hydroxy-4,5-dimethoxybenzaldehyde, and 4-hydroxy-2,6-dimethoxybenzaldehyde, and preferably 2-hydroxy-4,5-dimethoxybenzaldehyde.

[0014] In the present invention, hydroxy-methoxybenzaldehyde compounds are used to compound the second alumina. After compounding, the surface properties of the second alumina are improved, the surface energy is reduced, and the second alumina particles are more easily and uniformly dispersed in the slurry. During the forming process, the uniformly dispersed particles can be packed more closely to form a denser and more ordered microstructure. This dense structure reduces internal pores and defects. When subjected to external forces, the stress can be transmitted more evenly throughout the structure, avoiding the generation and propagation of cracks caused by stress concentration, thereby improving the mechanical strength of the ceramic substrate.

[0015] As a further technical solution, the preparation method of the hydroxy-methoxybenzaldehyde compounds compounded with the second alumina includes the following steps: dispersing the hydroxy-methoxybenzaldehyde compounds in a solution, adding the second alumina, and after mixing, filtering and drying to obtain the hydroxy-methoxybenzaldehyde compounds compounded with the second alumina.

[0016] As a further technical solution, the mass ratio of the hydroxy-methoxybenzaldehyde compounds to the second alumina is 2-3:20.

[0017] As a further technical solution, the solution is anhydrous ethanol, and the mass ratio of the solution to the second alumina is 10:1.

[0018] As a further technical solution, the mixing time is 2 h.

[0019] As a further technical solution, the plasticizer includes one or two of dibutyl phthalate and dioctyl phthalate.

[0020] In the present invention, a plasticizer is added. The plasticizer imparts a certain flexibility to the green body, making it not easily broken due to external forces during the forming process. In the preparation of multi-layer ceramic substrates, the green body may need to undergo process operations such as laminating and cutting. If the green body lacks flexibility, cracks are likely to occur during these operations. However, the addition of the plasticizer enables it to withstand a certain degree of bending and deformation, ensuring the smooth progress of the forming process.

[0021] As a further technical solution, the sintering aid includes one or more of calcium oxide, yttrium oxide, and cerium oxide.

[0022] In the present invention, sintering aids such as calcium oxide, yttrium oxide, and cerium oxide can reduce the sintering temperature, promote the densification of the ceramic and the refinement of grains. The dense structure and uniformly fine grains can improve the ability of the material to resist external forces, reduce the generation and propagation of cracks. In the preparation of multi-layer ceramic substrates, good mechanical properties can ensure that the substrate is not easily damaged during processing and use, improving the reliability of the product.

[0023] As a further technical solution, the binder includes one or more of acrylate, polyvinyl alcohol, and polyvinyl butyral, preferably acrylate.

[0024] In the present invention, a binder is added. The main function of the binder is to form a connecting bridge between ceramic powder particles, enhance the binding force between them, and firmly bond the dispersed particles together. During the preparation process of the multi-layer ceramic substrate, this strong binding force ensures that the green body can maintain a specific shape during the forming process and prevents the separation and movement of particles.

[0025] As a further technical solution, the dispersant includes one or two of sodium polyacrylate and triethyl phosphate.

[0026] In the present invention, a dispersant is added, which effectively prevents the agglomeration of each particle and makes them uniformly dispersed in the slurry. This uniformly dispersed state can ensure that each raw material is fully contacted during the mixing process, laying a foundation for the subsequent formation of a uniform microstructure.

[0027] The present invention also provides a method for preparing a low dielectric loss multi-layer ceramic substrate, which includes the following steps:

[0028] S1. Mix alumina, a plasticizer, a sintering aid, a dispersant, and water to obtain a mixture;

[0029] S2. Add a binder to the mixture to obtain a slurry, and the slurry is formed by tape casting to obtain a green ceramic sheet;

[0030] S3. After punching the green ceramic sheet, perform surface printing, lamination, through-hole conduction, cutting, and sintering, and then cool to obtain a multi-layer ceramic substrate.

[0031] As a further technical solution, the number of laminated layers is 30 to 60 layers.

[0032] As a further technical solution, the shape of the punching in S3 is circular, and the diameter of the circle is 100 to 150 μm.

[0033] As a further technical solution, the raw material for the surface printing in S3 is tungsten paste, and the thickness of the surface printing is 15 to 20 μm.

[0034] In the present invention, using tungsten paste as the printing raw material, tungsten has a high electrical conductivity. Using tungsten paste for surface printing can form a conductive circuit on the surface of the multi-layer ceramic substrate, and the conductive layer formed by tungsten paste has a low resistance, which can effectively reduce the heat loss of electric energy during transmission and avoid performance degradation caused by overheating.

[0035] As a further technical solution, the sintering temperature in S3 is 800 - 900 °C, the sintering time is 30 - 60 min, and the sintering atmosphere is air.

[0036] The working principle and beneficial effects of the present invention are as follows:

[0037] In the present invention, alumina is used as the raw material, and by reasonably matching plasticizers, binders, sintering aids, dispersants, etc., a multi-layer ceramic substrate is prepared. The plasticizer imparts a certain flexibility to the substrate, effectively improving its brittleness, enabling the substrate to better resist external forces during processing and use, and reducing the risk of cracking; the binder enhances the bonding force between the components, greatly improving the overall structural strength and stability of the substrate, ensuring that it can still maintain good physical forms and properties in complex environments; the sintering aid can reduce the sintering temperature, promote densification, and optimize the microstructure of the ceramic substrate; the dispersant can improve the fluidity of the slurry, ensure that the thickness of the formed substrate is uniform, the surface is flat, and reduce internal defects; by simultaneously using the first alumina and the second alumina with different morphologies, the synergistic effect of the two is exerted, making the microstructure of the ceramic substrate more dense, reducing the pores and defects inside the ceramic substrate, and thereby reducing the dielectric loss of the multi-layer ceramic substrate. Specific embodiments

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of the present invention.

[0039] In the following examples and comparative examples:

[0040] The first alumina: spherical alumina, with an average particle size of 3 - 5 μm;

[0041] The second alumina: flaky alumina, with an average particle size of 3 nm;

[0042] Calcium oxide: with a fineness of 325 mesh;

[0043] Yttrium oxide: with an average particle size of 1 μm;

[0044] Cerium oxide: with an average particle size of 1 μm;

[0045] Stacking layers: 30 layers;

[0046] Surface printing thickness: 15 μm.

[0047] Example 1

[0048] A preparation method of a low dielectric loss multi-layer ceramic substrate, comprising the following steps:

[0049] S1. Weigh 90 parts of alumina, 1 part of dibutyl phthalate, 3 parts of calcium oxide, 1 part of triethyl phosphate, and 50 parts of water, and stir to obtain a mixture, wherein the alumina is composed of a first alumina and a second alumina with a mass ratio of 2:1;

[0050] S2. Add 6 parts of acrylate to the mixture, stir to obtain a slurry, and the slurry is formed by tape casting to obtain a green ceramic sheet;

[0051] S3. After punching the green ceramic sheet to form a through hole with a diameter of 100 μm, after surface printing tungsten paste with a thickness of 20 μm, stack 30 green ceramic sheets together, the stacking pressure is 10 MPa, cut after conduction up and down, sinter at a temperature of 800 °C for 60 min, the sintering atmosphere is air, and a multi-layer ceramic substrate is obtained after cooling.

[0052] Example 2

[0053] A preparation method of a low dielectric loss multi-layer ceramic substrate, comprising the following steps:

[0054] S1. Weigh 95 parts of alumina, 2 parts of dioctyl phthalate, 4 parts of yttrium oxide, 2 parts of triethyl phosphate, and 55 parts of water, and stir to obtain a mixture, wherein the alumina is composed of a first alumina and a second alumina with a mass ratio of 2:1;

[0055] S2. Add 8 parts of acrylate to the mixture, stir to obtain a slurry, and the slurry is formed by tape casting to obtain a green ceramic sheet;

[0056] S3. After punching the green ceramic sheet to form a through hole with a diameter of 120 μm, after surface printing tungsten paste with a thickness of 15 μm, stack 30 green ceramic sheets together, the stacking pressure is 10 MPa, cut after conduction up and down, sinter at a temperature of 850 °C for 45 min, the sintering atmosphere is air, and a multi-layer ceramic substrate is obtained after cooling.

[0057] Example 3

[0058] A preparation method of a low dielectric loss multi-layer ceramic substrate, comprising the following steps:

[0059] S1. Weigh 100 parts of alumina, 3 parts of dioctyl phthalate, 5 parts of cerium oxide, 3 parts of triethyl phosphate, and 60 parts of water, and stir to obtain a mixture, wherein the alumina is composed of a first alumina and a second alumina with a mass ratio of 2:1;

[0060] S2. Add 10 parts of acrylate to the mixture, stir to obtain a slurry, and the slurry is formed by tape casting to obtain a green ceramic sheet;

[0061] S3. After drilling holes in the green ceramic chips to form through-holes with a diameter of 150 μm, after printing tungsten paste with a thickness of 20 μm on the surface, stack 30 green ceramic chips together, with a stacking pressure of 10 MPa. After achieving upper and lower conduction, cut the stack, and sinter it at a temperature of 900 °C for 30 min. The sintering atmosphere is air. After cooling, a multilayer ceramic substrate is obtained.

[0062] Example 4

[0063] Compared with Example 3, the difference in Example 4 is that the alumina consists of a first alumina and a second alumina with a mass ratio of 3:1.

[0064] Example 5

[0065] The preparation method of the hydroxy-methoxybenzaldehyde compound composite with the second alumina includes the following steps: Disperse 5 parts of 4-hydroxy-2-methoxybenzaldehyde in 500 parts of absolute ethanol, add 50 parts of the second alumina, mix for 2 h, and then filter and dry to obtain the hydroxy-methoxybenzaldehyde compound composite with the second alumina.

[0066] Compared with Example 3, the difference in Example 5 is that the second alumina is replaced with an equal amount of the hydroxy-methoxybenzaldehyde compound composite with the second alumina obtained by the above preparation method.

[0067] Example 6

[0068] Compared with Example 5, the difference in Example 6 is that 4-hydroxy-2-methoxybenzaldehyde is replaced with an equal amount of 2-hydroxy-4,5-dimethoxybenzaldehyde.

[0069] Example 7

[0070] Compared with Example 5, the difference in Example 7 is that 4-hydroxy-2-methoxybenzaldehyde is replaced with an equal amount of 4-hydroxy-2,6-dimethoxybenzaldehyde.

[0071] Example 8

[0072] Compared with Example 6, the difference in Example 8 is that the addition amount of 2-hydroxy-4,5-dimethoxybenzaldehyde is 7.5 parts.

[0073] Example 9

[0074] Compared with Example 5, the difference in Example 9 is that 4-hydroxy-2-methoxybenzaldehyde is replaced with an equal amount of p-hydroxybenzaldehyde.

[0075] Comparative Example 1

[0076] Compared with Example 3, the difference in Comparative Example 1 is that the alumina is the first alumina.

[0077] Comparative Example 2

[0078] Compared with Example 3, the difference in Comparative Example 2 is that the alumina is the second alumina.

[0079] Experimental Example 1

[0080] For the multi-layer ceramic substrates prepared in Examples 1 to 4 and Comparative Examples 1 to 2, the dielectric loss was measured using a broadband dielectric impedance analyzer E4990A, and the test frequency was 10 6 Hz, and the dielectric loss value of the multi-layer ceramic substrate was read.

[0081] The test results are shown in Table 1:

[0082] Table 1 Performance test results of the multi-layer ceramic substrates prepared in Examples 1 to 4 and Comparative Examples 1 to 2

[0083]

[0084] As can be seen from Table 1, the dielectric losses of Examples 1 to 4 are less than those of Comparative Examples 1 and 2, indicating that the first alumina and the second alumina play a synergistic role and can reduce the dielectric loss of the multi-layer ceramic substrate.

[0085] Experimental Example 2

[0086] For the multi-layer ceramic substrates prepared in Example 3 and Examples 5 to 9, according to the test method specified in GB / T 6569-2006 "Test Method for Flexural Strength of Fine Ceramics", the flexural strength of the samples was tested, and the test method was three-point bending.

[0087] The test results are shown in Table 2:

[0088] Table 2 Performance test results of the multi-layer ceramic substrates prepared in Example 3 and Examples 5 to 9

[0089]

[0090] As can be seen from Table 2, in Examples 5 to 8, hydroxy-methoxybenzaldehyde compounds were added to compound the second alumina. As a result, the flexural strengths of Examples 5 to 7 were higher than those of Example 3 and Example 9, indicating that the addition of hydroxy-methoxybenzaldehyde compounds compounded with the second alumina can enhance the mechanical strength of the multi-layer ceramic substrate.

[0091] Among Examples 5 to 7, the flexural strength of Example 6 was higher than that of Examples 5 and 7, indicating that when the hydroxy-methoxybenzaldehyde compound was 2-hydroxy-4,5-dimethoxybenzaldehyde, the mechanical strength of the obtained multi-layer ceramic substrate was higher.

[0092] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A low dielectric loss multilayer ceramic substrate, characterized in that: The invention comprises the following raw materials in parts by weight: 90-100 parts of aluminum oxide, 1-3 parts of a plasticizer, 3-5 parts of a sintering aid, 6-10 parts of a binder, 1-3 parts of a dispersant, and 50-60 parts of water. The aluminum oxide is composed of a first aluminum oxide and a second aluminum oxide. The first aluminum oxide and the second aluminum oxide have different forms. The first alumina is spherical alumina, the second alumina is flaky alumina, and the mass ratio of the first alumina to the second alumina is 2-3:1; The second aluminum oxide is a hydroxymethoxybenzaldehyde compound composite second aluminum oxide.

2. The low dielectric loss multilayer ceramic substrate according to claim 1, characterized in that: The average particle size of the first aluminum oxide is 3-5 μm, and the average particle size of the second aluminum oxide is 3 nm.

3. The low dielectric loss multilayer ceramic substrate according to claim 1, characterized in that: The hydroxymethoxybenzaldehyde compound includes one or more of 4-hydroxy-2-methoxybenzaldehyde, 2-hydroxy-4,5-dimethoxybenzaldehyde, and 4-hydroxy-2,6-dimethoxybenzaldehyde.

4. The low dielectric loss multilayer ceramic substrate according to claim 1, characterized in that: Also includes at least one of the following technical features: The plasticizer includes one or two of dibutyl phthalate and dioctyl phthalate; The sintering aid includes one or more of calcium oxide, yttrium oxide, and cerium oxide; The binder includes one or more of acrylate, polyvinyl alcohol, and polyvinyl butyral; The dispersant includes one or both of sodium polyacrylate and triethyl phosphate.

5. The method for preparing a low dielectric loss multilayer ceramic substrate according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, mixing alumina, a plasticizer, a sintering aid, a dispersant, and water to obtain a mixture; S2, adding a binder to the mixture to obtain a slurry, and performing tape casting to obtain a green porcelain sheet; S3, after punching holes in the green ceramic sheet, surface printing, lamination, upper and lower conduction, cutting, sintering, and cooling, a multilayer ceramic substrate is obtained.

6. The method for preparing a low dielectric loss multilayer ceramic substrate according to claim 5, characterized in that: The shape of the punched hole in S3 is circular, and the diameter of the circle is 100-150 μm.

7. The method for preparing a low dielectric loss multilayer ceramic substrate according to claim 5, characterized in that: The raw material for surface printing in S3 is tungsten paste.

8. The method for preparing a low dielectric loss multilayer ceramic substrate according to claim 5, characterized in that: The sintering temperature in S3 is 800-900° C., the sintering time is 30-60 min, and the sintering atmosphere is air.

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