Alumina ceramic substrate material, method of manufacture and use

Abstract

This invention relates to the field of electronic packaging substrates, and particularly to an alumina ceramic substrate material, its preparation method, and its application. The alumina ceramic substrate comprises 90-99 wt% alumina and 1-10 wt% sintering aids. The sintering aids have the following composition: xB₂O₃·zSiO₂·yBi₂O₃, where 15≦x≦25, 50≦y≦70, 15≦z≦25, and x+y+z=100, where x:y:z is the mass ratio. The density of the alumina ceramic substrate is ≥3.8 g / cm³. 3 The alumina ceramic substrate of this invention has the following characteristics: surface roughness ≤ 0.35 μm, breakdown strength ≥ 35 kV / mm, bending angle ≥ 350 MPa, and thermal conductivity ≥ 25 W / m·K. It also features high density, uniform microstructure, good surface flatness, high mechanical strength, high breakdown strength, low dielectric loss, and high thermal conductivity.

Description

Technical Field

[0001] This invention relates to the field of electronic packaging substrates, and in particular to an alumina ceramic substrate material, its preparation method, and its application. Background Technology

[0002] With the rapid development of new energy technologies, power electronics technology has received increasing attention. Due to the continuous increase in operating voltage and device power, power electronic devices / components generate more and more heat during operation. If this heat cannot be transferred or dissipated in a timely manner, it will cause localized overheating, thereby affecting the device's efficiency and, in severe cases, leading to device failure.

[0003] However, traditional polymer PCBs cannot meet the aforementioned heat dissipation requirements due to their low thermal conductivity. Furthermore, traditional PCBs have weak mechanical properties, making them unsuitable for operation in certain high-intensity environments. Therefore, the need for ceramic substrates has increased dramatically. Among numerous candidate materials, alumina has attracted significant attention due to its wide availability, stable physical / chemical properties, strong mechanical properties, good electrical properties, ease of processing, and relatively low cost.

[0004] However, alumina generally has low sintering activity and requires high sintering temperatures. Sintering at excessively high temperatures can lead to excessive grain growth, resulting in weakened mechanical properties. In addition, excessively high sintering temperatures increase energy consumption, leading to increased costs. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of low sintering activity, high sintering temperature, and weak mechanical properties of current alumina ceramic substrates as described in the background art. Here, a new alumina ceramic substrate material, preparation method, and application are proposed. The preparation process of this alumina ceramic substrate is simple and time-saving, and it reduces the sintering temperature, improves production efficiency, and reduces production costs.

[0006] The technical solution adopted by the present invention to solve its technical problem is: an alumina ceramic substrate material, wherein the alumina ceramic substrate material comprises 90-99 wt% alumina and 1-10 wt% sintering aid, wherein the sintering aid is xB2O3·zSiO2·yBi2O3, 15≦x≦25, 50≦y≦70, 15≦z≦25, x+y+z=100, wherein x:y:z is the mass ratio.

[0007] Preferably, the alumina ceramic substrate material comprises 93-97 wt% alumina and 3-7 wt% sintering aids.

[0008] Preferably, the sintering aid is xB2O3·zSiO2·yBi2O3, 15≦x≦20, 60≦y≦70, 15≦z≦20, x+y+z=100, where x:y:z is the mass ratio.

[0009] In this invention, the alumina ceramic substrate material uses alumina as the base material and adds appropriate sintering aids. The green body is prepared by tape casting process and finally sintered to form an alumina ceramic substrate. The alumina ceramic substrate preferably comprises 90-99 wt% alumina and 1-10 wt% sintering aids, more preferably 93-97 wt% alumina and 3-7 wt% sintering aids, and even more preferably 95 wt% alumina and 5 wt% sintering aids. The sintering aids preferably have the following composition: xB2O3·zSiO2·yBi2O3, 15≦x≦25, 50≦y≦70, 15≦z≦25, x+y+z=100, where x:y:z is the mass ratio. More preferably, it is 15≦x≦20, 60≦y≦70, 15≦z≦20, and even more preferably x=20, z=60, y=20.

[0010] An alumina ceramic substrate made from the alumina ceramic substrate material as described above, wherein the alumina ceramic substrate is prepared by the following method:

[0011] S1. Take the prescribed amounts of B2O3, SiO2, and Bi2O3 raw materials, and prepare a sintering aid by first-stage ball milling, drying, calcination, and second-stage ball milling.

[0012] S2. The sintering aid, alumina and mixing aid in the formula are mixed and ball-milled in three stages to obtain a slurry;

[0013] S3. The slurry is defoamed and cast to obtain a green ceramic tape;

[0014] S4. The green ceramic strip is cut, degreased, and sintered under normal pressure to obtain an alumina ceramic substrate;

[0015] The atmospheric pressure sintering temperature is 1500-1650℃, the time is 2-12h, the heating rate is 0.5-10℃ / min, and the furnace is allowed to cool down naturally after sintering.

[0016] The first, second, and third stage ball milling processes all use deionized water as the medium for wet ball milling; the mixing aids include solvents, dispersants, binders, and plasticizers.

[0017] Preferably, the first, second, and third stage ball mills all use stainless steel grinding jars and zirconium dioxide grinding balls. The diameter of the zirconium dioxide grinding balls is 1-5 mm, the ball-to-material ratio is (1-3):1, the ball milling speed is 100-300 rpm, the ball milling time is 2-24 h, and the solid content is 50-70 wt%.

[0018] Preferably, the calcination in step S1 is carried out at a temperature of 600-900℃ for 2-12 hours, with a heating rate of 0.5-10℃ / min, and the furnace is allowed to cool down naturally after calcination.

[0019] Preferably, the solvent is a mixture of ethanol and xylene; the dispersant is one or more of castor oil, trioleic acid glyceride, and Span 80; the binder is polyvinyl butyral; and the plasticizer is one or more of dibutyl phthalate, diethyl phthalate, and polyethylene glycol.

[0020] Preferably, based on the total mass of sintering aid and alumina, the amount of solvent added is 40-80 wt%; the amount of dispersant added is 1-4 wt%; the amount of binder added is 2-14 wt%; and the amount of plasticizer added is 2-14 wt%.

[0021] Preferably, the density of the alumina ceramic substrate is ≥3.8 g / cm³. 3 Surface roughness ≤0.35μm.

[0022] Preferably, based on the total mass of sintering aid and alumina, the mass fraction of the sintering aid is 5 wt%, and the composition of the sintering aid is xB2O3·zSiO2·yBi2O3, where x = 20, z = 60, and y = 20, and x:y:z is the mass ratio.

[0023] In this invention, the primary, secondary, and tertiary ball mills preferably use stainless steel grinding jars and zirconium dioxide grinding balls. The diameter of the zirconium dioxide grinding balls is preferably 1-5 mm, more preferably 1 mm. The ball-to-material ratio (the mass ratio of grinding balls to raw materials; in primary and secondary ball milling, it is the mass ratio of grinding balls to the total mass of B2O3, SiO2, and Bi2O3; in tertiary ball milling, it is the mass ratio of grinding balls to the total mass of sintering aids and alumina) is preferably (1-3):1, more preferably 2:1 in primary and secondary ball milling, and more preferably (2-3):1 in tertiary ball milling. The ball milling speed is preferably 100-300 rpm. The ball milling process is preferably 200 rpm for the first and second stages and 250 rpm for the third stage. The ball milling time is preferably 2-24 h, preferably 4 h for the first and second stages and 6 h for the third stage. The solid content (the percentage of the mass of B2O3, SiO2, and Bi2O3 raw materials to the total mass of raw materials and media in the first and second stages and the percentage of the total mass of sintering aids and alumina to the mass of slurry in the third stage) is preferably 50-70 wt%, preferably 65 wt% for the first and second stages and 50 wt% for the third stage.

[0024] In this invention, the calcination in step S1 is preferably carried out at a temperature of 600-900℃, more preferably at 700℃; the calcination time is preferably 2-12h, more preferably 4h.

[0025] In this invention, the mixed additives include a solvent, a dispersant, a binder, and a plasticizer. The solvent is preferably a mixture of ethanol and xylene. The dispersant is preferably one or more of castor oil, trioleic acid glyceride, and Span 80, more preferably trioleic acid glyceride. The binder is preferably polyvinyl butyral. The plasticizer is preferably one or more of dibutyl phthalate, diethyl phthalate, and polyethylene glycol, more preferably a mixture of dibutyl phthalate, diethyl phthalate, and polyethylene glycol.

[0026] In this invention, based on the total mass of sintering aid and alumina as 100%, the amount of solvent added is preferably 40-80 wt%, more preferably 37.5 wt% ethanol and 37.5 wt% xylene; the amount of dispersant added is preferably 1-4 wt%, more preferably 1 wt% trioleic acid glyceride; the amount of binder added is preferably 2-14 wt%, more preferably 12 wt% polyvinyl butyral; the amount of plasticizer added is preferably 2-14 wt%, more preferably 12 wt% of a mixture of dibutyl phthalate, diethyl phthalate, and polyethylene glycol, wherein the mass ratio of dibutyl phthalate, diethyl phthalate, and polyethylene glycol is 1:1:1.

[0027] An application of an alumina ceramic substrate as described above in electronic device packaging.

[0028] The beneficial effects of this invention are: the sintering aid provided by this invention can effectively reduce the sintering temperature of alumina, and result in alumina ceramic plates with high density (≥3.89 g / cm³). 3 Uniform microstructure, good surface smoothness, high mechanical strength (≥560MPa), high breakdown strength (≥16kV / mm), and low dielectric loss (≤10). -4 Features include high thermal conductivity (≥30W / m·K) and high thermal conductivity (@1MHz). Attached Figure Description

[0029] Figure 1 The X-ray diffraction (XRD) pattern of the alumina ceramic substrate prepared in Example 5;

[0030] Figure 2 This is a scanning electron microscope (SEM) image of the alumina ceramic substrate prepared in Example 5. Detailed Implementation

[0031] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] The present invention will now be further illustrated with specific examples. The following embodiments are only for explaining the present invention and do not constitute a limitation thereof. The test samples and test procedures used in the following embodiments include the following (if the specific experimental conditions are not specified in the embodiments, they are usually performed according to conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following embodiments can be obtained commercially unless otherwise specified).

[0034] Example 1

[0035] An alumina ceramic substrate has the following raw material ratio: 95 wt% Al2O3 and 5 wt% sintering aid; the chemical composition of the sintering aid is a mixture of xB2O3·zSiO2·yBi2O3, wherein x=15, y=70, z=15, and x:y:z is the weight ratio.

[0036] The preparation method of this alumina ceramic substrate is as follows:

[0037] (1) According to the chemical composition of the sintering aid, the amount of B2O3, SiO2 and Bi2O3 raw materials in the formula are put into a stainless steel grinding jar with zirconium dioxide grinding balls. The mass ratio of zirconium dioxide grinding balls to B2O3, SiO2 and Bi2O3 raw materials is controlled to be 2:1. Deionized water is added as the ball milling medium and the solid content is controlled to be 65wt%. Then, the ball milling is carried out in the stainless steel grinding jar at a rate of 200rpm for 4h. After the ball milling is completed, the dry powder is obtained. The dry powder is calcined and heated to 700℃ at a heating rate of 1℃ / min. The temperature is held for 4h and then cooled with the furnace to obtain calcined powder. The calcined powder is repeated in the first-stage ball milling step to obtain the sintering aid.

[0038] (2) Weigh out the sintering aid and alumina of the formula amount, mix them, add the mixing aid and mix again, and add it to the stainless steel grinding jar. Control the mass ratio of zirconium dioxide grinding balls to B2O3, SiO2 and Bi2O3 raw materials to be 2:1. Add deionized water as the ball milling medium and control the solid content to be 50wt%. Then, ball mill in the stainless steel grinding jar at a speed of 250rpm for 6h to obtain a slurry. The mixing aid is a solvent (a mixture of ethanol and xylene), a dispersant (trioleyl glycerol), a binder (polyvinyl butyral) and a plasticizer (a mixture of dibutyl phthalate, diethyl phthalate and polyethylene glycol). Based on the total mass of sintering aid and alumina as 100%, the amount of ethanol added is 37.5wt%, xylene is 37.5wt%, trioleyl glycerol is 1wt%, polyvinyl butyral is 12wt%, and phthalic acid, dibutyl phthalate and polyethylene glycol are mixed in a mass ratio of 1:1:1 to 12wt%.

[0039] (3) After the slurry is defoamed, it is cast into green ceramic tape using a casting machine;

[0040] (4) The green ceramic strip is cut according to the required size requirements. After degreasing, the cut sample is sintered at a temperature of 1570℃, a holding time of 8h, and a heating rate of 1℃ / min to finally obtain an alumina ceramic substrate.

[0041] Example 2

[0042] An alumina ceramic substrate is provided, wherein the raw material ratio is 95 wt% Al2O3 and 5 wt% sintering aid; the chemical composition of the sintering aid is a mixture of xB2O3·zSiO2·yBi2O3, wherein x = 20, y = 60, z = 20, and x:y:z is the weight ratio; the preparation method of the alumina ceramic substrate is the same as that in Example 1.

[0043] Example 3

[0044] An alumina ceramic substrate is provided, wherein the raw material ratio is 95 wt% Al2O3 and 5 wt% sintering aid; the chemical composition of the sintering aid is a mixture of xB2O3·zSiO2·yBi2O3, wherein x = 25, y = 50, z = 25, and x:y:z is the weight ratio; the preparation method of the alumina ceramic substrate is the same as that in Example 1.

[0045] Example 4

[0046] An alumina ceramic substrate has a raw material ratio of 99 wt% Al2O3 and 1 wt% sintering aid; the ratio of the sintering aid and the preparation method of the alumina ceramic substrate are the same as in Example 1.

[0047] Example 5

[0048] An alumina ceramic substrate has a raw material ratio of 97 wt% Al2O3 and 3 wt% sintering aid; the ratio of sintering aid and the preparation method of the alumina ceramic substrate are the same as in Example 1.

[0049] Example 6

[0050] An alumina ceramic substrate has a raw material ratio of 93 wt% Al2O3 and 7 wt% sintering aid; the ratio of sintering aid and the preparation method of the alumina ceramic substrate are the same as in Example 1.

[0051] Example 7

[0052] An alumina ceramic substrate has a raw material ratio of 90 wt% Al2O3 and 10 wt% sintering aid; the ratio of the sintering aid and the preparation method of the alumina ceramic substrate are the same as in Example 1.

[0053] The sintering aids, calcined powders, and alumina ceramic substrates prepared in Examples 1-7 were subjected to phase analysis by XRD, particle size and morphology analysis by SEM, and mechanical and electrical property measurements. The XRD and SEM images of the alumina ceramic substrate prepared in Example 5 are shown below. Figure 1 , Figure 2 .

[0054] The density and surface roughness of the alumina ceramic substrates prepared in Examples 1-7 were tested, and the test results are shown in Table 1.

[0055] Density was determined by the water displacement method.

[0056] Surface roughness detection method: using a surface topography instrument.

[0057] Table 1

[0058]

[0059] The alumina ceramic substrates prepared in Examples 1-7 have a breakdown strength ≥35kV / mm, a bending angle ≥350MPa, and a thermal conductivity ≥25W / m·K.

[0060] As can be seen from Examples 1-3 in Table 1, in the chemical composition of the sintering aid xB2O3·zSiO2·yBi2O3, the increase in the content of B2O3 and Bi2O3 is beneficial to the increase of the density of the alumina ceramic substrate and the reduction of the surface roughness of the alumina ceramic substrate. As can be seen from Examples 1 and 4-7, as the content of alumina relative to the sintering aid increases, the density of the alumina ceramic substrate first increases and then decreases, and the surface roughness also decreases slightly first and then increases. This is because if the amount of sintering aid is too low, the desired effect will not be achieved, while if the content is too high, it will accumulate at the grain boundaries and have an adverse effect on the surface roughness.

[0061] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0062] The foregoing has provided a detailed description of an alumina ceramic substrate, its preparation method, and its applications. Specific examples have been used to illustrate the principles and implementation methods of the invention. These examples are merely illustrative and are intended to aid in understanding the method and core concepts of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. An alumina ceramic substrate material, characterized in that: The alumina ceramic substrate material comprises 90-99 wt% alumina and 1-10 wt% sintering aid, wherein the sintering aid is... x B2O3· z SiO2· y Bi2O3, 15≦ x ≤20, 60≦ y ≤70, 15≦ z ≤20, x + y + z =100, where, x : y : z It is the mass ratio; The alumina ceramic substrate obtained from the aforementioned alumina ceramic substrate material is prepared by the following method: S1. Take the prescribed amounts of B2O3, SiO2, and Bi2O3 raw materials, and prepare a sintering aid by first-stage ball milling, drying, calcination, and second-stage ball milling. S2. The sintering aid, alumina and mixing aid in the formula are mixed and ball-milled in three stages to obtain a slurry; S3. The slurry is defoamed and cast to obtain a green ceramic tape; S4. The green ceramic strip is cut, degreased, and sintered under normal pressure to obtain an alumina ceramic substrate; The atmospheric pressure sintering temperature is 1500-1650℃, the time is 2-12 h, the heating rate is 0.5-10ºC / min, and the furnace is allowed to cool down naturally after sintering. The primary, secondary, and tertiary ball milling processes all use deionized water as the medium for wet ball milling; the mixing aids include solvents, dispersants, binders, and plasticizers; The calcination described in step S1 is carried out at a temperature of 600-900℃ for 2-12 hours, with a heating rate of 0.5-10ºC / min. After calcination, the furnace is allowed to cool down naturally.

2. The alumina ceramic substrate material according to claim 1, characterized in that: The alumina ceramic substrate material comprises 93-97 wt% alumina and 3-7 wt% sintering aids.

3. An alumina ceramic substrate made from the alumina ceramic substrate material according to claim 1, characterized in that: The alumina ceramic substrate is prepared by the following method: S1. Take the prescribed amounts of B2O3, SiO2, and Bi2O3 raw materials, and prepare a sintering aid by first-stage ball milling, drying, calcination, and second-stage ball milling. S2. The sintering aid, alumina and mixing aid in the formula are mixed and ball-milled in three stages to obtain a slurry; S3. The slurry is defoamed and cast to obtain a green ceramic tape; S4. The green ceramic strip is cut, degreased, and sintered under normal pressure to obtain an alumina ceramic substrate; The atmospheric pressure sintering temperature is 1500-1650℃, the time is 2-12 h, the heating rate is 0.5-10ºC / min, and the furnace is allowed to cool down naturally after sintering. The first, second, and third stage ball milling processes all use deionized water as the medium for wet ball milling; the mixing aids include solvents, dispersants, binders, and plasticizers.

4. The alumina ceramic substrate according to claim 3, characterized in that: The first, second, and third stage ball mills all use stainless steel grinding jars and zirconium dioxide grinding balls. The diameter of the zirconium dioxide grinding balls is 1-5 mm, the ball-to-material ratio is (1-3):1, the ball milling speed is 100-300 rpm, the ball milling time is 2-24 h, and the solid content is 50-70 wt%.

5. The alumina ceramic substrate according to claim 3, characterized in that: The solvent is a mixture of ethanol and xylene; the dispersant is one or more of castor oil, trioleic acid glyceride, or Span 80; the binder is polyvinyl butyral; and the plasticizer is one or more of dibutyl phthalate, diethyl phthalate, or polyethylene glycol.

6. The alumina ceramic substrate according to claim 3, characterized in that: Based on the total mass of sintering aid and alumina as 100%, the amount of solvent is 40-80 wt%; the amount of dispersant is 1-4 wt%; the amount of binder is 2-14 wt%; and the amount of plasticizer is 2-14 wt%.

7. The alumina ceramic substrate according to claim 3, characterized in that: The density of the alumina ceramic substrate is ≥3.8 g / cm³. 3 Surface roughness ≤ 0.35 μm.

8. An application of the alumina ceramic substrate as described in claim 3 in electronic device packaging.

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