Breakthrough-resistant multilayer ceramic substrate and preparation method thereof

Abstract

The invention relates to the technical field of ceramic substrates, and provides an anti-breakdown multilayer ceramic substrate and a preparation method thereof. The breakdown-resistant multilayer ceramic substrate comprises the following raw materials in parts by weight: 85-95 parts of aluminum oxide, 4-6 parts of a first sintering aid, 2-3 parts of a second sintering aid, 2-4 parts of a dispersing agent, 7-9 parts of a binder, 2-3 parts of a plasticizer and 60-70 parts of water, the preparation method of the first sintering aid comprises the following steps: uniformly mixing silicon dioxide and strontium oxide, melting, quenching, cooling, and carrying out ball milling to obtain the first sintering aid; the second sintering aid is a rare earth oxide. According to the technical scheme, the problem of insufficient breakdown resistance of the multilayer ceramic substrate in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic substrate, in particular, it relates to anti-breakdown multilayer ceramic substrate and its preparation method. BACKGROUND

[0002] As the core packaging material in the field of electronic information and power electronics, multilayer ceramic substrate is widely used in key scenarios such as high-power IGBT modules, 5G base station radio frequency components and new energy vehicle power control systems, due to its excellent insulation performance, thermal conductivity and structural integration. The core performance of this kind of substrate includes mechanical strength, thermal stability and dielectric properties, among which the anti-breakdown strength as a key indicator to measure its insulation reliability directly determines the voltage level and operation safety of electronic devices.

[0003] If the anti-breakdown strength of multilayer ceramic substrate is insufficient, it will cause a series of chain adverse consequences: light causes the device voltage resistance to decline, limiting its application in high-voltage scenarios; heavy causes insulation breakdown under high electric field, causing circuit short circuit, chip burning and other sudden failures, and even endangering life and property safety. Improving the anti-breakdown strength of multilayer ceramic substrate is the core demand to ensure the safe and stable operation of electronic equipment and promote the progress of high-end electronic packaging technology. Therefore, it is necessary to propose an anti-breakdown multilayer ceramic substrate and its preparation method. SUMMARY

[0004] The present application proposes an anti-breakdown multilayer ceramic substrate and its preparation method, which solves the problem of insufficient anti-breakdown capacity of multilayer ceramic substrate in the prior art.

[0005] The technical scheme of the present application is as follows: The present application proposes an anti-breakdown multilayer ceramic substrate, which comprises the following components by weight: 85-95 parts of alumina, 4-6 parts of first sintering aid, 2-3 parts of second sintering aid, 2-4 parts of dispersant, 7-9 parts of binder, 2-3 parts of plasticizer and 60-70 parts of water; the preparation method of the first sintering aid comprises the following steps: uniformly mixing strontium oxide and silicon dioxide and ball milling for 3-5h, melting the ball-milled mixture and directly quenching, obtaining glassy first sintering aid fragments after cooling, wet ball milling the first sintering aid glass fragments for 24h, using ethanol as the medium in the wet ball milling process, and obtaining the first sintering aid after ball milling, the particle size of the first sintering aid is 3μm; the second sintering aid is rare earth oxide.

[0006] As a further technical scheme, the mass ratio of strontium oxide and silicon dioxide in the first sintering aid is 1-4:4, for example, it can be 1:4, 1:2, 3:4, 1:1, preferably 3:4.

[0007] When the mass ratio of strontium oxide and silicon dioxide is less than 1:4, the amount of the glass phase formed is insufficient and the viscosity is high, which reduces the wetting and filling effect on the alumina particles, weakens the sintering driving force, and causes the substrate to have a high porosity and insufficient density, thereby affecting the anti-breakdown performance and structural stability of the anti-breakdown multilayer ceramic substrate; when the mass ratio of the two is greater than 1:1, excessive strontium oxide makes the glass phase too fluid, and excessive melting occurs during the sintering process, which easily causes the substrate to deform; when the mass ratio of strontium oxide and silicon dioxide is 1-4:4, the appropriate low-melting-point glass phase can be formed during the sintering process, which provides sufficient liquid phase for the sintering of the alumina particles and promotes the formation of a dense structure during the sintering process, thereby further improving the anti-breakdown performance of the anti-breakdown multilayer ceramic substrate.

[0008] As a further technical solution, the second sintering aid is samarium oxide.

[0009] In the raw material of the anti-breakdown multilayer ceramic substrate, the second sintering aid is samarium oxide, which is easy to accumulate at the grain boundaries of the alumina during the ceramic sintering process, thereby hindering the ion migration path and inhibiting abnormal grain growth caused by excessive ion migration, avoiding the formation of coarse grains, and ultimately promoting the ceramic matrix to form a more uniform and fine grain structure, significantly reducing the porosity and improving the overall density, thereby further enhancing the anti-breakdown performance of the multilayer ceramic substrate.

[0010] As a further technical solution, it also includes the following raw materials in weight parts: 5-7 parts of modified sericite; the modified sericite is obtained by modifying sericite with phenyl carbamate.

[0011] In the raw material of the anti-breakdown multilayer ceramic substrate, sericite has a unique sheet structure and excellent properties such as high anti-breakdown voltage, and is often used as a filler to improve the anti-breakdown capability of the material. However, sericite has the problem of easy agglomeration, which makes it difficult to achieve the effect of improving the anti-breakdown voltage. The present application improves the dispersibility of sericite by surface modification with phenyl carbamate, which can further improve the anti-breakdown performance of the anti-breakdown multilayer ceramic substrate.

[0012] As a further technical solution, the mass ratio of phenyl carbamate to sericite in the modified sericite is 5-9:90, for example, it can be 1:18, 1:15, 7:90, 4:45, 1:10, and preferably 7:90.

[0013] As a further technical solution, the preparation method of the modified sericite includes the following steps: dispersing phenyl carbamate in anhydrous ethanol, then adding sericite, mixing for 3h, drying, and obtaining modified sericite; the mass-volume ratio of the sericite to anhydrous ethanol is 1g:10mL.

[0014] As a further technical solution, the dispersing agent comprises one or more of sodium tripolyphosphate, polyacrylamide, and sodium citrate.

[0015] As a further technical solution, the plasticizer comprises one or both of polyethylene glycol and glycerol.

[0016] As a further technical solution, the binder comprises one or both of polyvinyl alcohol and sodium carboxymethyl cellulose.

[0017] The present application also provides a preparation method of the anti-breakdown multilayer ceramic substrate, comprising the following steps: S1, mixing alumina, a first sintering aid, a second sintering aid, a dispersing agent, and water to obtain a mixture; S2, adding the remaining raw materials of the anti-breakdown multilayer ceramic substrate to the mixture, and performing casting, drying to obtain a green ceramic sheet; S3, after punching the green ceramic sheet, performing surface printing, lamination, up-down conduction, cutting, sintering, and cooling to obtain the anti-breakdown multilayer ceramic substrate.

[0018] As a further technical solution, in step S3, the shape of the punching is circular, and the diameter of the circular shape is 60-90 μm, for example, 60 μm, 70 μm, 80 μm, or 90 μm.

[0019] As a further technical solution, in step S3, the sintering temperature is 1200-1400℃, for example, 1200℃, 1300℃, or 1400℃, the sintering time is 30-60 min, for example, 30 min, 40 min, 45 min, or 60 min, and the sintering atmosphere is nitrogen.

[0020] The working principle and beneficial effects of the present application are as follows: The anti-breakdown multilayer ceramic substrate prepared by the application takes alumina as the main body, and the anti-breakdown performance of the substrate is significantly improved by adding a first sintering aid prepared from silicon dioxide and strontium oxide and rare earth oxides as a second sintering aid. In the prior art, the sintering aid combines with part of the alumina to form a co-sintering phase in the liquid phase sintering process, which destroys the original composition structure of the ceramic and further affects the performance. In contrast, the first sintering aid prepared from silicon dioxide and strontium oxide can generate a lower-melting-point glass phase when sintering forms a liquid phase. This low-melting-point glass phase not only can effectively fill the gaps between alumina particles, promote particle diffusion and densification, but also can inhibit the excessive growth of alumina grains, avoid the generation of structural defects due to the coarse grains, and reduce the porosity, thereby improving the anti-breakdown capability of the multilayer ceramic substrate. In addition, the rare earth oxides as the second sintering aid can further inhibit the grain growth by hindering the migration of other ions and reducing the grain boundary migration rate, helping to form a more dense ceramic structure, and further enhancing the anti-breakdown performance of the multilayer ceramic substrate. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0022] In the following examples and comparative examples, the particle size of the alumina is 20 μm; the particle size of the strontium oxide is 180 μm; the particle size of the silicon dioxide is 5 μm; the particle size of the samarium oxide is 1 μm; the carboxymethyl cellulose sodium is a product with the model number LT-011, which is purchased from the Renqiu Litian Chemical Co., Ltd.; the polyacrylamide has a weight average molecular weight of 12 million; the polyvinyl alcohol has a model number PVA-1788; the polyethylene glycol has a model number PEG200; and the sericite has a particle size of 44 μm.

[0023] Example 1 A preparation method of an anti-breakdown multilayer ceramic substrate, comprising the following steps: S1, 85 parts of alumina, 4 parts of a first sintering aid, 2 parts of samarium oxide, 2 parts of sodium tripolyphosphate and 60 parts of water are mixed to obtain a mixture; S2, 7 parts of polyvinyl alcohol and 2 parts of polyethylene glycol are added to the mixture and mixed to obtain a green ceramic sheet by casting and drying; S3, the green ceramic sheet is punched in the shape of a circle with a diameter of 70 μm, and then surface printing, layering (20 layers), upper and lower conduction, cutting, sintering and cooling are performed to obtain an anti-breakdown multilayer ceramic substrate; wherein the sintering temperature is 1300℃, the time is 45 min, and the atmosphere is nitrogen; The preparation method of the first sintering aid includes the following steps: uniformly mixing strontium oxide and silicon dioxide with a mass ratio of 1:4, ball-milling and dispersing for 4 hours, melting the silicon dioxide at 1720 DEG C, quenching, obtaining glassy first sintering aid fragments after cooling, wet ball-milling the first sintering aid glass fragments for 24 hours, using ethanol as the medium in the wet ball-milling process, and obtaining the first sintering aid after ball-milling, wherein the particle size of the first sintering aid is 3 microns.

[0024] Example 2 A preparation method of an anti-breakdown multilayer ceramic substrate includes the following steps: S1, 90 parts of aluminum oxide, 5 parts of the first sintering aid (the same as in Example 1), 2.5 parts of samarium oxide, 2 parts of polyacrylamide, 1 part of sodium citrate, and 65 parts of water are mixed to obtain a mixture; S2, 4 parts of polyvinyl alcohol, 4 parts of sodium carboxymethyl cellulose, 2 parts of polyethylene glycol, and 0.5 parts of glycerol are added to the mixture and mixed, cast formed, dried to obtain a green ceramic sheet; S3, the green ceramic sheet is punched in a circular shape with a diameter of 70 microns, then surface printed, laminated (20 layers), up and down conductive, cut, sintered, and cooled to obtain an anti-breakdown multilayer ceramic substrate; wherein the sintering temperature is 1300 DEG C, the time is 45 minutes, and the atmosphere is nitrogen.

[0025] Example 3 A preparation method of an anti-breakdown multilayer ceramic substrate includes the following steps: S1, 95 parts of aluminum oxide, 6 parts of the first sintering aid (the same as in Example 1), 3 parts of samarium oxide, 4 parts of sodium citrate, and 70 parts of water are mixed to obtain a mixture; S2, 9 parts of sodium carboxymethyl cellulose and 3 parts of glycerol are added to the mixture and mixed, cast formed, dried to obtain a green ceramic sheet; S3, the green ceramic sheet is punched in a circular shape with a diameter of 70 microns, then surface printed, laminated (20 layers), up and down conductive, cut, sintered, and cooled to obtain an anti-breakdown multilayer ceramic substrate; wherein the sintering temperature is 1300 DEG C, the time is 45 minutes, and the atmosphere is nitrogen.

[0026] Example 4 Compared with Example 3, the difference between Example 4 is only that the mass ratio of strontium oxide and silicon dioxide in the first sintering aid in this embodiment is 3:4.

[0027] Example 5 Compared with Example 3, the difference between Example 5 is only that the mass ratio of strontium oxide and silicon dioxide in the first sintering aid in this embodiment is 1:1.

[0028] Example 6 Compared with Example 3, the difference of Example 6 is only that, in the preparation of the anti-breakdown multilayer ceramic substrate in this embodiment, step S2 is: adding 9 parts of sodium carboxymethyl cellulose, 3 parts of glycerol, and 6 parts of modified sericite into the mixture, mixing, casting, drying, and obtaining the green ceramic sheet; The preparation method of the modified sericite comprises the following steps: dispersing phenyl carbamate in anhydrous ethanol, then adding sericite, mixing for 3 hours, and drying to obtain the modified sericite; wherein the mass ratio of phenyl carbamate to sericite is 1:18, and the mass-volume ratio of sericite to anhydrous ethanol is 1g:10mL.

[0029] Example 7 Compared with Example 6, the difference of Example 7 is only that, in the modified sericite in this embodiment, the mass ratio of phenyl carbamate to sericite is 7:90.

[0030] Example 8 Compared with Example 6, the difference of Example 8 is only that, in the modified sericite in this embodiment, the mass ratio of phenyl carbamate to sericite is 1:10.

[0031] Example 9 Compared with Example 6, the difference of Example 9 is only that, in this embodiment, the modified sericite is replaced by an equal amount of sericite.

[0032] Comparative Example 1 Compared with Example 3, the difference of Comparative Example 1 is only that, in this comparative example, the samarium oxide is replaced by an equal amount of the first sintering aid.

[0033] Comparative Example 2 Compared with Example 3, the difference of Comparative Example 2 is only that, in this comparative example, the first sintering aid is replaced by an equal amount of samarium oxide.

[0034] Comparative Example 3 Compared with Example 3, the difference of Comparative Example 3 is only that, in this comparative example, the strontium oxide in the first sintering aid is replaced by an equal amount of silicon dioxide.

[0035] Comparative Example 4 Compared with Example 3, the difference of Comparative Example 4 is only that, in this comparative example, the silicon dioxide in the first sintering aid is replaced by an equal amount of strontium oxide.

[0036] The anti-breakdown multilayer ceramic substrate is tested according to the following method: 1. Breakdown strength test: according to the test method specified in 5.13 of GB / T 5593-2015 "Electronic component structure ceramic material", the breakdown strength test is carried out under direct current condition, and the voltage rising rate is 500V / s; The measurement results are shown in Tables 1-2: Table 1 Breakdown strength test results of the breakdown-resistant multilayer ceramic substrate

[0037] From the data in Table 1, the breakdown strength of the breakdown-resistant multilayer ceramic substrate in Examples 1-5 is higher than that of Comparative Examples 1-2, indicating that the addition of the first sintering aid and the second sintering aid can reduce the sintering temperature of the breakdown-resistant multilayer ceramic substrate and improve its breakdown strength; the breakdown strength of the breakdown-resistant multilayer ceramic substrate in Examples 1-5 is higher than that of Comparative Examples 3-4, indicating that the addition of the first sintering aid composed of strontium oxide and silicon dioxide can improve the breakdown strength of the breakdown-resistant multilayer ceramic substrate.

[0038] Table 2 Breakdown strength test results of the breakdown-resistant multilayer ceramic substrate

[0039] From the data in Table 2, the breakdown strength of the breakdown-resistant multilayer ceramic substrate in Examples 6-8 is higher than that of Example 3 and Example 9, indicating that the addition of the phenyl carbamate modified sericite significantly improves the breakdown strength of the breakdown-resistant multilayer ceramic substrate.

[0040] The above is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A multilayer ceramic substrate resistant to breakdown, characterized in that, The raw material comprises the following components in parts by weight: 85-95 parts of alumina, 4-6 parts of a first sintering aid, 2-3 parts of a second sintering aid, 2-4 parts of a dispersing agent, 7-9 parts of a binder, 2-3 parts of a plasticizer, and 60-70 parts of water; the first sintering aid is prepared by the following steps: uniformly mixing silica and strontium oxide, melting, quenching, and ball milling to obtain the first sintering aid; and the second sintering aid is a rare earth oxide.

2. The anti-punch through multi-layer ceramic substrate of claim 1, wherein, The mass ratio of strontium oxide to silica in the first sintering aid is 1-4:

4.

3. The anti-punch through multilayer ceramic substrate of claim 1, wherein, The second sintering aid is samarium oxide.

4. The anti-punch through multi-layer ceramic substrate of claim 1, wherein, The raw material further comprises the following components in parts by weight: 5-7 parts of modified sericite; the modified sericite is obtained by modifying sericite with phenyl carbamate.

5. The anti-punch through multilayer ceramic substrate of claim 4, wherein, The mass ratio of phenyl carbamate to sericite in the modified sericite is 5-9:

90.

6. The anti-punch through multilayer ceramic substrate of claim 1, wherein, The dispersing agent comprises one or more of sodium tripolyphosphate, polyacrylamide, and sodium citrate.

7. The anti-punch through multilayer ceramic substrate of claim 1, wherein, The plasticizer comprises one or both of polyethylene glycol and glycerol.

8. The anti-punch through multilayer ceramic substrate of claim 1, wherein, The binder comprises one or both of polyvinyl alcohol and sodium carboxymethyl cellulose.

9. A method for producing a multilayer ceramic substrate resistant to breakdown, for producing the multilayer ceramic substrate resistant to breakdown according to any one of claims 1 to 8, characterized by, The method comprises the following steps: S1, mixing alumina, the first sintering aid, the second sintering aid, the dispersing agent, and water to obtain a mixture; S2, adding the remaining raw material for resisting breakdown of a multilayer ceramic substrate to the mixture, and performing casting, drying, to obtain a green ceramic sheet; S3, perforating the green ceramic sheet, and performing surface printing, lamination, up-and-down conduction, cutting, sintering, and cooling to obtain the multilayer ceramic substrate resisting breakdown.

10. The method for preparing a breakdown-resistant multilayer ceramic substrate according to claim 9, characterized in that, In step S3, the sintering temperature is 1200-1400℃.

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