A ceramic package base and a method for manufacturing the same

Abstract

The application belongs to the technical field of electronic components, and particularly relates to a ceramic packaging base and a preparation method thereof. Through control of inorganic components of ceramic slurry and content thereof, the application realizes accurate control of types of crystal phase precipitation at grain boundaries of alumina grains and content of precipitated phases, so that the mechanical strength of the prepared ceramic base is greatly improved, and excellent mechanical properties can still be maintained under the conditions of miniaturization and thin layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic components, and in particular relates to a ceramic packaging base and a preparation method thereof. Background Art

[0002] In recent years, with the continuous miniaturization and multifunctionality of electronic equipment products such as mobile phones and laptops, the precision electronic components such as wafers or chips used in their internal structures also need to be gradually miniaturized, and the requirements for the ceramic packaging base that protects them have also increased accordingly.

[0003] For ceramic package bases, the mechanical strength of the package deteriorates after the design of small specifications and thin layers. Therefore, how to improve the mechanical strength of the ceramic base itself while maintaining thin layers and small specifications has become a research hotspot. Summary of the Invention

[0004] In response to the problems of poor mechanical strength of the ceramic package base in the above-mentioned prior art, the present invention provides a ceramic package base and a preparation method thereof.

[0005] To achieve the above objectives, the following technical solutions are specifically included:

[0006] A ceramic package base includes a ceramic substrate and a conductive layer, wherein the ceramic substrate includes a main crystalline phase, a secondary crystalline phase and a glass phase of aluminum oxide; the secondary crystalline phase includes MgAl2O4, Al2TiO5, LaAl 11 O 18 Three precipitated phases are present, and the mass ratio of Mg, Ti and La in the secondary crystalline phase and the glassy phase is Mg:Ti:La=(0.6-1):(0.3-0.9):(0.4-0.9).

[0007] During the sintering process, Al2O3 grains will gradually grow as the temperature rises. However, excessive growth of grains will significantly reduce the mechanical strength of the ceramic base. In order to inhibit the growth of grains, additives are added to generate specific crystal phases, so that the sintered ceramic substrate has a main crystal phase of alumina and MgAl2O4, Al2TiO5 and LaAl2O4 precipitated at the grain boundaries of the alumina grains. 11 O 18 The crystal structure of the secondary phase is controlled by MgAl2O4, Al2TiO5 and LaAl 11 O 18 The precipitation of the three subcrystalline phases and the mass ratio of the specific elements Mg, Ti, and La in the subcrystalline phases and the glass phase enable the three subcrystalline phases to precipitate simultaneously and assist each other in enhancing the mechanical strength of the ceramic substrate.

[0008] Preferably, the ceramic substrate includes 92-94 wt% Al calculated as Al2O3, 2.5-3.5% Si calculated as SiO2, 0.5-1.5% Ca calculated as CaCO3, 1-1.5% Mg calculated as MgO, 0.5-1.5% Ti calculated as TiO2, and 0.5-1% La calculated as La2O3.

[0009] Preferably, the mass ratio of the total mass of Al in the ceramic substrate to the mass of Mg in the secondary crystalline phase and the glass phase is (48.5-49.5):(0.6-1).

[0010] Preferably, the secondary crystalline phase contains MgAl2O4, Al2TiO5, LaAl 11 O 18 The mass ratio of the three precipitated phases is (2-3): (1-3): (1-2). Under the above mass ratio of the three subcrystalline phases, the ceramic substrate has better mechanical strength.

[0011] A method for preparing the ceramic package base comprises the following steps:

[0012] (1) subjecting the ceramic slurry to tape casting, printing a conductive layer, and lamination in sequence to obtain a ceramic package base green body;

[0013] Taking the mass percentage of the ceramic slurry as 100%, the ceramic slurry includes the following components in mass percentage: 45-55% of inorganic component, 30-40% of organic solvent, 5-10% of organic resin, 2-5% of plasticizer, and 0.5-1% of dispersant;

[0014] Taking the mass percentage of the inorganic components as 100%, the inorganic components include the following mass percentages: Al2O3 92-94%, SiO2 2.5-3.5%, CaCO3 0.5-1.5%, MgO 1-1.5%, TiO2 0.5-1.5%, and La2O3 0.5-1%;

[0015] (2) The ceramic package base green body is sequentially subjected to debinding, sintering, and metal coating to obtain the ceramic package base.

[0016] The present invention controls the composition and content of inorganic components in the preparation of ceramic packaging base, so that the ceramic substrate can form a main crystal phase of aluminum oxide and precipitate specific components of MgAl2O4, Al2TiO5 and LaAl at the grain boundaries of aluminum oxide grains. 11 O 18The crystalline phase structure and the amorphous glass phase are simultaneously precipitated at the Al2O3 grain boundaries, which play a pinning role to inhibit abnormal grain growth, promote grain refinement, reduce sintering temperature and increase density. The glass phase further promotes sintering to achieve the purpose of improving the mechanical strength of the ceramic package base.

[0017] In the technical solution of the present invention, it is necessary to control the composition and content of the inorganic components to achieve precise control of the type of crystalline phase and the precipitation content at the grain boundaries of the alumina grains. The reasons are as follows:

[0018] Part of the added MgO forms glass with SiO2 / CaCO3, promoting the sintering process, while the excess MgO reacts with Al2O3 to form MgAl2O4. The small grains of MgAl2O4 act as pins on the Al2O3 grain boundaries, inhibiting grain growth. At the same time, the MgAl2O4 grains fill the gaps between the Al2O3 grains, effectively dispersing the force transmitted to the gaps and avoiding the degradation effect of the pores. Although the generation of MgAl2O4 inhibits the growth of Al2O3 grains, the MgAl2O4 grains generated in the system are limited and cannot pin the grain boundaries of all Al2O3 grains. Therefore, the pinned alumina grains grow slowly, while the grains that are not pinned can grow normally, thereby improving the mechanical properties of the ceramic package base.

[0019] When the amount of MgO added is too low, MgO and Al2O3 are completely dissolved in solid, and there is no residual MgO to react with Al2O3 to form MgAl2O4, which has no pinning effect on the grain boundaries; when the amount of MgO added is too high, the amount of MgO added exceeds the amount required for the reaction, and excessive MgAl2O4 grains are generated, which pin the grain boundaries of excessive Al2O3 grains, affecting the normal growth of Al2O3 grains, making it difficult to sinter the ceramic base and having poor performance;

[0020] TiO2 and Al2O3 have different valences and ionic radii, so the added TiO2 will react with Al2O3 to produce defects, resulting in main lattice distortion and cation vacancies. These defects promote the diffusion rate of Al2O3 in the system, reduce the sintering temperature of the ceramic substrate, and promote the grain refinement of the Al2O3 ceramic. In addition, TiO2 and Al2O3 form Al2TiO5 phase, which fills the gaps in the crystals, removes pores, reduces porosity, increases material density, and further improves the mechanical properties of the ceramic base.

[0021] TiO2 is added in too small amount, which can not generate specific Al2TiO5 phase, so that the density of the ceramic system is reduced; too much TiO2 is added, which can cause too much Al2TiO5 phase in the system, and the sintering temperature of the ceramic is increased, which can cause rapid growth of Al2O3 grains at high temperature, and affect the material performance;

[0022] By introducing rare earth oxide La2O3 into the ceramic substrate, the rare earth cation radius is much larger than the aluminum ion, and the difference in ion radius makes the solid solution degree of La element in Al small, and it is difficult to form a solid solution, so the added La2O3 mainly exists in the Al2O3 grain boundary, at this time, the La2O3 with glass network structure has large volume, and the migration resistance of itself in the structure is large, and can hinder the migration of other ions, reduce the grain boundary migration rate, and inhibit the growth of Al2O3 grains, and improve the strength of the ceramic base;

[0023] When La2O3 is too little, La element exists in Al2O3 grains in the form of solid solution, which cannot realize the effect of fixing Al2O3 grains, and cannot inhibit the abnormal growth of Al2O3 grains; when La2O3 is added in too much amount, it can cause the appearance of more coarse rod-like LaAl 11 O 18 phase in the system, and can cause the appearance of coarse Al2O3 grains, which can reduce the density of the ceramic and cause the reduction of the mechanical properties of the ceramic.

[0024] Preferably, the heating rate of the sintering is 120-200℃ / min, and the cooling rate of the sintering is 60-110℃ / min.

[0025] Further preferably, the heating rate of the sintering is 120-180℃ / min, and the cooling rate of the sintering is 80-110℃ / min.

[0026] Preferably, the temperature of the degassing is 350-550℃, and the time of the degassing is 2-4h.

[0027] Preferably, the temperature of the sintering is 1250-1450℃, and the time of the sintering is 1-5h.

[0028] The sintering process has an effect on the growth of the grains, and further has an effect on the mechanical properties of the ceramic base, and under the above-mentioned heating rate or cooling rate, the mechanical strength of the ceramic base is better.

[0029] Preferably, the average particle size of the Al2O3 is 0.1-3μm.

[0030] More preferably, the average particle size of the Al2O3 is normally distributed, and even more preferably, the average particle size of the Al2O3 is 1 to 2 μm, and the proportion of aluminum oxide is 70% to 80%.

[0031] Using Al2O3 powder with a normal distribution of particle size and content, on the basis of regular filling, powders with larger particle sizes still have pores between particles under the densest packing, while powders with small particle sizes in different ranges can be filled into the gaps to obtain a higher density aggregate. Compared with the use of nano-scale small powders of uniform size, the density and sintering activity are improved, and the corresponding strength and mechanical properties are better.

[0032] Preferably, the inorganic components include the following components in percentage by mass: Al2O3 92-93%, SiO2 3%, CaCO3 1%, MgO 1.2-1.5%, TiO2 1-1.5%, La2O3 0.8-1%. Under the above component contents, the ceramic substrate has better mechanical strength.

[0033] Preferably, the organic solvent includes at least one of toluene, ethanol, xylene, butanone, and isopropyl alcohol; the organic resin includes at least one of acrylate and polyvinyl butyral (PVB); the plasticizer includes at least one of castor oil, polyethylene glycol (PEG), dibutyl phthalate (DBP), and dioctyl phthalate (DOP); and the dispersant includes at least one of stearic acid, fish oil, and acrylate.

[0034] Preferably, the debinding and sintering atmosphere is a mixed gas atmosphere of nitrogen and hydrogen; the metal plating layer is a nickel layer and a gold layer in sequence; and the conductive layer in the printed conductive layer is a tungsten layer or a molybdenum layer.

[0035] Compared with the prior art, the present invention has the following beneficial effects: the present invention controls the inorganic components and contents of the ceramic slurry to achieve precise control of the type of crystal phase and the content of the precipitated phase at the grain boundaries of the alumina grains, thereby greatly improving the mechanical strength of the prepared ceramic base, and maintaining excellent mechanical properties while meeting the requirements of miniaturization and thin-layering. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a field emission scanning electron microscope (FE-SEM) image of the ceramic substrate of Example 1. The grain 1 marked in the figure is MgAl2O4 and the grain 2 is LaAl 11 O 18 , grain 3 is Al2TiO5.

[0037] Figure 2 The MgAl2O4 grains, LaAl 11O 18 Transmission electron microscope (TEM) electron diffraction patterns of Al2TiO5 grains, the left, middle and right pictures correspond to MgAl2O4 grains, LaAl 11 O 18 Transmission electron microscopy (TEM) electron diffraction patterns of grains and Al2TiO5 grains. DETAILED DESCRIPTION

[0038] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be further described below with reference to specific examples. The experimental methods used in the examples and / or comparative examples are conventional methods unless otherwise specified; the materials and reagents used are commercially available unless otherwise specified.

[0039] The alumina particles in the following examples and comparative examples have a size range of 0.1 to 3 μm and are normally distributed, with the alumina particles having a size distribution range of 1 to 2 μm accounting for 70% to 80% by mass.

[0040] Example 1

[0041] A method for preparing a ceramic package base comprises the following steps:

[0042] (1) Based on the mass percentage of the ceramic slurry being 100 wt%, 50 wt% of an inorganic component, 40 wt% of ethanol, 5 wt% of PVB, 4 wt% of DOP, and 1 wt% of stearic acid were weighed and uniformly mixed to form a ceramic slurry, and a ceramic green body was obtained by tape casting;

[0043] Wherein, based on the mass percentage of the inorganic component being 100 wt%, the raw materials of the specific inorganic component are weighed according to Table 1, and the content of the remaining components is 3 wt% SiO2 and 1 wt% CaCO3;

[0044] (2) processing the ceramic green body into a desired structural shape according to different structural requirements and pattern requirements of the conductive layer, further printing a tungsten conductive layer, and then laminating the layers to obtain a ceramic package base green body;

[0045] (3) The ceramic package base green body is debinded and sintered in a mixed atmosphere of nitrogen and hydrogen. Specifically, the temperature is first raised to the debinding temperature to fully remove organic matter, and then the temperature is continued to be raised to the sintering temperature and kept at this temperature for sintering. After sintering, the temperature is uniformly lowered. The debinding temperature is 450°C, the debinding time is 3h, the sintering temperature is 1300°C, and the sintering time is 4h. The heating rate and cooling rate during sintering are shown in Table 1. After cooling, the nickel layer and the gold layer are plated in sequence to obtain the finished ceramic package base.

[0046] Examples 2-5

[0047] The difference from Example 1 lies in the composition and content of the inorganic components, as shown in Table 1.

[0048] Examples 6-7

[0049] The difference from Example 1 lies in the heating rate and cooling rate during the sintering process, as shown in Table 1.

[0050] Example 8

[0051] The difference from Example 1 lies in the content of each component of the ceramic slurry. Specifically, 45 wt% inorganic component, 39.5 wt% ethanol, 10 wt% PVB, 5 wt% DOP, and 0.5 wt% stearic acid are weighed and uniformly mixed to form the ceramic slurry.

[0052] Example 9

[0053] The difference from Example 1 lies in the content of each component of the ceramic slurry. Specifically, 55 wt% inorganic component, 30 wt% ethanol, 9 wt% PVB, 5 wt% DOP, and 1 wt% stearic acid are weighed and uniformly mixed to form the ceramic slurry.

[0054] Example 10

[0055] The difference from Example 1 lies in the content of each component of the ceramic slurry. Specifically, 53.7 wt% inorganic component, 35.5 wt% ethanol, 7 wt% PVB, 3 wt% DOP, and 0.8 wt% stearic acid are weighed and uniformly mixed to form the ceramic slurry.

[0056] Example 11

[0057] The difference from Example 1 lies in the components of the ceramic slurry. Specifically, 50 wt% of inorganic components, 40 wt% of xylene, 5 wt% of acrylate, 4 wt% of castor oil, and 1 wt% of fish oil are weighed and uniformly mixed to form the ceramic slurry.

[0058] Example 12

[0059] The difference from Example 1 is the contents of the remaining components except the inorganic components in Table 1, specifically 2.5 wt% SiO2 and 1.5 wt% CaCO3.

[0060] Example 13

[0061] The difference from Example 1 is the contents of the remaining components except the inorganic components in Table 1, specifically 3.5 wt% SiO2 and 0.5 wt% CaCO3.

[0062] Examples 14-15

[0063] The difference from Example 1 lies in the heating rate and cooling rate during the sintering process, as shown in Table 1.

[0064] Comparative Examples 1-6

[0065] The difference from Example 1 lies in the composition and content of the inorganic components, as shown in Table 1.

[0066] Comparative Example 7

[0067] The difference from Example 1 lies in the inorganic components and content, specifically 93wt% Al2O3, 0.5wt% MgO, 1wt% BaCO3, 0.5Cr2O3, 1wt% La2O3, 3wt% SiO2, and 1wt% CaCO3.

[0068] Comparative Example 8

[0069] The difference from Example 1 lies in the inorganic components and content, specifically 93wt% Al2O3, 0.5wt% MgO, 0.5wt% BaCO3, 0.5wt% TiO2, 0.5MnO2, 1wt% La2O3, 3wt% SiO2, and 1wt% CaCO3.

[0070] Table 1

[0071]

[0072] The ceramic package base prepared above was subjected to performance testing, and the testing method is shown in Table 2.

[0073] Table 2

[0074]

[0075]

[0076] The crystal phase test results are as follows Figure 1-2 As shown, the ceramic substrate in the ceramic package base prepared in Examples 1-15 of the present invention comprises an aluminum oxide main crystalline phase, a secondary crystalline phase and a glass phase; the secondary crystalline phase comprises MgAl2O4, Al2TiO5, LaAl 11 O 18 The three precipitated phases are calculated based on the mass of Al in the ceramic substrate and the mass of Mg, Ti and La in the secondary crystalline phase and the glassy phase. The mass of MgAl2O4, Al2TiO5, LaAl2O4 in the secondary crystalline phase is calculated based on the mass of Al in the inorganic raw materials used to prepare the ceramic substrate. 11 O 18The mass ratio of the three precipitated phases was calculated by X-ray diffraction combined with the Rietveld method. The crystallinity was calculated by the peak area ratio and the quantitative data information between the three subcrystalline phases was obtained by combining the least square fitting of the measured diffraction patterns. 11 O 18 The precipitation conditions and mass ratios of the three subcrystalline phases are shown in Table 3.

[0077] Table 3 (based on 100 wt.% of ceramic substrate)

[0078]

[0079]

[0080]

[0081] Table 4

[0082]

[0083]

[0084] From Examples 1-15 and Comparative Examples 1-8, it can be seen that MgAl2O4, Al2TiO5, LaAl 11 O 18 When the three secondary crystalline phases are all precipitated at the grain boundaries of the main crystalline phase alumina and the mass ratio of Mg, Ti and La is within the range, the bending strength and density of the ceramic package base are qualified, and it is a high-strength ceramic package base.

[0085] It can be seen from Examples 1-4 that when the mass ratio of Al in the ceramic package base to Mg in the secondary crystalline phase and the glass phase is within the preferred range, the density and bending strength of the ceramic substrate are excellent.

[0086] It can be seen from Examples 1-2, 5 and 3-4 that MgAl2O4, Al2TiO5, LaAl 11 O 18 When the mass ratio of the three precipitated phases is within the above range, the bending resistance of the ceramic package base is better.

[0087] It can be seen from Examples 1, 6-7 and 14-15 that the heating and cooling rates of the sintering process have a certain influence on the bending strength and density of the ceramic package base. When the sintering heating rate is 120-200℃ / min and the sintering cooling rate is 60-110℃ / min, the bending strength and density of the ceramic package base are better.

[0088] From the examples 1, 8-13, it can be seen that the ceramic slurry with the component types and contents in the range provided in the application can obtain the high-strength ceramic packaging base with good bending strength and density performance.

[0089] From the examples 1-5 and 6-15, it can be seen that when the inorganic component content and the sintering temperature rising and falling rate are in the preferred range, the bending strength and density performance of the ceramic packaging base are better.

[0090] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the application and not to limit the protection scope of the application. Although the application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the application.

Claims

1. A ceramic package base, characterized in that: It includes a ceramic substrate and a conductive layer, wherein the ceramic substrate includes a main crystalline phase, a secondary crystalline phase and a glass phase of aluminum oxide; the secondary crystalline phase includes MgAl2O4, Al2TiO5, LaAl 11 O 18 Three precipitated phases are present, and the mass ratio of Mg, Ti and La in the secondary crystalline phase and the glassy phase is Mg:Ti:La=(0.6-1):(0.3-0.9):(0.4-0.9).

2. The ceramic package base according to claim 1, wherein: The mass ratio of the total mass of Al in the ceramic substrate to the mass ratio of Mg in the secondary crystalline phase and the glass phase is (48.5-49.5): (0.6-1).

3. The ceramic package base according to claim 1, wherein: The secondary crystalline phase contains MgAl2O4, Al2TiO5, LaAl 11 O 18 The mass ratio of the three precipitated phases is (2-3):(1-3):(1-2).

4. A method for preparing the ceramic package base according to any one of claims 1 to 3, characterized in that: The steps include: (1) subjecting the ceramic slurry to tape casting, printing a conductive layer, and lamination in sequence to obtain a ceramic package base green body; Taking the mass percentage of the ceramic slurry as 100%, the ceramic slurry includes the following components in mass percentage: 45-55% of inorganic component, 30-40% of organic solvent, 5-10% of organic resin, 2-5% of plasticizer, and 0.5-1% of dispersant; Taking the mass percentage of the inorganic components as 100%, the inorganic components include the following mass percentages: Al2O3 92-94%, SiO2 2.5-3.5%, CaCO3 0.5-1.5%, MgO 1-1.5%, TiO2 0.5-1.5%, and La2O3 0.5-1%; (2) The ceramic package base green body is sequentially subjected to debinding, sintering, and metal coating to obtain the ceramic package base.

5. The method for preparing a ceramic package base according to claim 4, wherein: The heating rate of the sintering is 120-200° C. / min, and the cooling rate of the sintering is 60-110° C. / min.

6. The method for preparing a ceramic package base according to claim 4, wherein: The debinding temperature is 350-550° C., and the debinding time is 2-4 hours.

7. The method for preparing a ceramic package base according to claim 4, wherein: The sintering temperature is 1250-1450° C., and the sintering time is 1-5 hours.

8. The method for preparing a ceramic package base according to claim 4, wherein: The average particle size of the Al2O3 is 0.1-3 μm.

9. The method for preparing a ceramic package base according to claim 4, wherein: The inorganic components include the following components in percentage by mass: Al2O3 92-93%, SiO2 3%, CaCO3 1%, MgO 1.2-1.5%, TiO2 1-1.5%, and La2O3 0.8-1%.

10. The method for preparing a ceramic package base according to claim 4, wherein: The organic solvent includes at least one of toluene, ethanol, xylene, butanone, and isopropyl alcohol; the organic resin includes at least one of acrylate and polyvinyl butyral; the plasticizer includes at least one of castor oil, polyethylene glycol, dibutyl phthalate, and dioctyl phthalate; and the dispersant includes at least one of stearic acid, fish oil, and acrylate.

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