A surface metallization process of alumina ceramic substrate

Abstract

The invention relates to the technical field of ceramic metallization, and in particular to a surface metallization process of an alumina ceramic substrate. The alumina ceramic substrate is firstly cleaned, and then a metallization slurry is prepared. The metallization slurry is prepared from the following raw materials in parts by weight: 80-100 parts of metal powder, 5-10 parts of glass powder, 1-2 parts of metal fluoride, and 15-30 parts of an organic carrier. The metallization slurry is screen-printed on the alumina ceramic substrate and dried, and then sintered in a nitrogen atmosphere. A test piece prepared by the process of the invention has high tensile strength, and can be used to make packaging, heat dissipation and conductive materials for electronic components.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic metallization, in particular to a surface metallization process of an alumina ceramic substrate. Background Art

[0002] Ceramic surface metallization can connect ceramics and metals to form a composite substrate, combining the excellent mechanical properties of ceramic materials with the excellent thermal and electrical conductivity of metal materials. The metallized ceramic substrate is mainly used as an electrical conductor for interconnecting devices and a thermal conductor for transferring heat from the device. At present, the main methods for ceramic surface metallization are: sintered metal powder method, direct copper coating method, active metallization method, thick film method, magnetron sputtering method, etc.

[0003] The thick film method is to apply metal slurry to the surface of the ceramic substrate by screen printing, and sinter it in a special gas environment to form a metallization layer on the ceramic substrate. Subsequently, the metal with a lower melting point than the base material is electroplated or sintered to finally achieve the interconnection between the ceramic substrate and the metal. However, the low bonding strength of the metallization layer will have an adverse effect on the subsequent interconnection between the ceramic substrate and the metal. How to improve the strength of the metallization layer has become a current research hotspot. Summary of the invention

[0004] Purpose of the invention: In view of the above technical problems, the present invention proposes a surface metallization process for an alumina ceramic substrate.

[0005] The technical solutions adopted are as follows:

[0006] A surface metallization process of an alumina ceramic substrate is as follows:

[0007] S1: cleaning the alumina ceramic substrate;

[0008] S2: Prepare metallization slurry, which is made of the following raw materials in parts by weight:

[0009] 80-100 parts of metal powder, 5-10 parts of glass powder, 1-2 parts of metal fluoride, and 15-30 parts of organic carrier;

[0010] S3: Screen printing the metallization slurry onto the alumina ceramic substrate and drying it, and then sintering it in a nitrogen atmosphere.

[0011] Furthermore, the metal powder includes molybdenum powder, manganese powder and aluminum powder.

[0012] Furthermore, the mass ratio of the molybdenum powder, manganese powder and aluminum powder is 70-90:5-10:1-5.

[0013] Furthermore, the glass powder includes Bi2O3, B2O3 and ZnO.

[0014] Furthermore, the preparation method of the glass powder is as follows:

[0015] Using anhydrous ethanol as a ball-milling medium, Bi2O3, B2O3 and ZnO are mixed and ball-milled, then dried, and then heated to 1300-1400°C in a crucible for smelting for 30-60 minutes. The obtained molten liquid is added to deionized water for quenching to obtain initial glass particles, which are then ball-milled again and dried.

[0016] Furthermore, the mass ratio of Bi2O3, B2O3 and ZnO is 10-15:2-4:1.

[0017] Furthermore, the metal fluoride is calcium fluoride and / or yttrium fluoride.

[0018] Furthermore, the organic carrier includes ethyl cellulose, terpineol, glycerol and melamine.

[0019] Furthermore, the mass ratio of the ethyl cellulose, terpineol, glycerol and melamine is 0.5-1:8-10:1-3:0.1-0.5.

[0020] Furthermore, the sintering temperature is 1350-1550°C.

[0021] Beneficial effects of the present invention:

[0022] The invention provides a surface metallization process for an alumina ceramic substrate. The bonding strength between a metallization layer and an alumina ceramic substrate is effectively enhanced by in-situ generated aluminum nitride nanowires, and the mechanical strength of the metallization layer itself is effectively improved. Melamine in an organic carrier is decomposed into highly active ammonia at high temperature, which can promote the nitridation reaction, increase the reaction rate, and generate more aluminum nitride nanowires. Metal fluorides can react with an oxide layer on the surface of aluminum powder to further promote the nitridation reaction. Moreover, the reaction products can diffuse into the pores generated by sintering to fill the pores, thereby improving the compactness of the metallization layer. In addition, metal fluorides can also react with the surface of the alumina ceramic substrate to form anchor points for bonding the metallization layer, thereby further improving the bonding strength between the metallization layer and the alumina ceramic substrate. After testing, the test piece prepared by the process of the invention has a higher tensile strength and can be used to make packaging, heat dissipation and conductive materials for electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a cross-sectional morphology diagram of the test piece prepared in Example 1, where the presence of aluminum nitride nanowires can be observed. DETAILED DESCRIPTION

[0024] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. The techniques not mentioned in the present invention are all referenced to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0025] Embodiment 1:

[0026] A surface metallization process of an alumina ceramic substrate:

[0027] First, the alumina ceramic substrate was placed in deionized water for ultrasonic cleaning for 5 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 5 minutes. After taking it out, the surface was blown dry with hot nitrogen.

[0028] Prepare metallization slurry, which is made of the following raw materials in parts by weight:

[0029] 80 parts of molybdenum powder, 6 parts of manganese powder, 4 parts of aluminum powder, 8 parts of Bi2O3-B2O3-ZnO glass powder, 2 parts of yttrium fluoride, 1 part of ethyl cellulose, 18 parts of pinene alcohol, 3 parts of glycerol, and 0.5 parts of melamine;

[0030] Using anhydrous ethanol as a ball-milling medium, a mixture of Bi2O3, B2O3 and ZnO in a mass ratio of 13.5:3:1 is ball-milled and dried, and then heated to 1350° C. in a crucible for 30 min. The obtained molten liquid is added to deionized water for quenching to obtain initial glass particles, and the initial glass particles are ball-milled again and dried to obtain Bi2O3-B2O3-ZnO glass powder;

[0031] Molybdenum powder, manganese powder, aluminum powder, Bi2O3-B2O3-ZnO glass powder and yttrium fluoride are ball-milled in a ball mill for 5 hours. The obtained mixed powder is mixed with ethyl cellulose, pine alcohol, glycerin and melamine, and then put into a vibration mill for vibration grinding for 5 hours. Finally, the metallization slurry is obtained after filtering with a nylon mesh. The metallization slurry is screen-printed onto an alumina ceramic substrate and dried, and then heated to 1450°C in a nitrogen atmosphere and sintered for 2 hours.

[0032] Embodiment 2:

[0033] A surface metallization process of an alumina ceramic substrate:

[0034] First, the alumina ceramic substrate was placed in deionized water for ultrasonic cleaning for 5 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 5 minutes. After taking it out, the surface was blown dry with hot nitrogen.

[0035] Prepare metallization slurry, which is made of the following raw materials in parts by weight:

[0036] 80 parts of molybdenum powder, 6 parts of manganese powder, 4 parts of aluminum powder, 10 parts of Bi2O3-B2O3-ZnO glass powder, 2 parts of yttrium fluoride, 1 part of ethyl cellulose, 18 parts of pinene alcohol, 3 parts of glycerol, and 0.5 parts of melamine;

[0037] Using anhydrous ethanol as a ball-milling medium, a mixture of Bi2O3, B2O3 and ZnO in a mass ratio of 13.5:3:1 is ball-milled and dried, and then heated to 1350° C. in a crucible for 30 min. The obtained molten liquid is added to deionized water for quenching to obtain initial glass particles, and the initial glass particles are ball-milled again and dried to obtain Bi2O3-B2O3-ZnO glass powder;

[0038] Molybdenum powder, manganese powder, aluminum powder, Bi2O3-B2O3-ZnO glass powder and yttrium fluoride are ball-milled in a ball mill for 5 hours. The obtained mixed powder is mixed with ethyl cellulose, pineol, glycerol and melamine, and then put into a vibration mill for 5 hours. Finally, the metallization slurry is obtained after filtering with a nylon mesh. The metallization slurry is screen-printed onto an alumina ceramic substrate and dried, and then heated to 1550°C in a nitrogen atmosphere and sintered for 4 hours.

[0039] Embodiment 3:

[0040] A surface metallization process of an alumina ceramic substrate:

[0041] First, the alumina ceramic substrate was placed in deionized water for ultrasonic cleaning for 5 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 5 minutes. After taking it out, the surface was blown dry with hot nitrogen.

[0042] Prepare metallization slurry, which is made of the following raw materials in parts by weight:

[0043] 80 parts of molybdenum powder, 6 parts of manganese powder, 4 parts of aluminum powder, 5 parts of Bi2O3-B2O3-ZnO glass powder, 1 part of yttrium fluoride, 1 part of ethyl cellulose, 18 parts of pinene alcohol, 3 parts of glycerol, and 0.5 parts of melamine;

[0044] Using anhydrous ethanol as a ball-milling medium, a mixture of Bi2O3, B2O3 and ZnO in a mass ratio of 13.5:3:1 is ball-milled and dried, and then heated to 1350° C. in a crucible for 30 min. The obtained molten liquid is added to deionized water for quenching to obtain initial glass particles, and the initial glass particles are ball-milled again and dried to obtain Bi2O3-B2O3-ZnO glass powder;

[0045] Molybdenum powder, manganese powder, aluminum powder, Bi2O3-B2O3-ZnO glass powder and yttrium fluoride are ball-milled in a ball mill for 5 hours. The obtained mixed powder is mixed with ethyl cellulose, pineol, glycerol and melamine, and then put into a vibration mill for vibration grinding for 5 hours. Finally, the metallization slurry is obtained after filtering with a nylon mesh. The metallization slurry is screen-printed onto an alumina ceramic substrate and dried, and then heated to 1400°C in a nitrogen atmosphere and sintered for 2 hours.

[0046] Embodiment 4:

[0047] A surface metallization process of an alumina ceramic substrate:

[0048] First, the alumina ceramic substrate was placed in deionized water for ultrasonic cleaning for 5 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 5 minutes. After taking it out, the surface was blown dry with hot nitrogen.

[0049] Prepare metallization slurry, which is made of the following raw materials in parts by weight:

[0050] 80 parts of molybdenum powder, 6 parts of manganese powder, 4 parts of aluminum powder, 8 parts of Bi2O3-B2O3-ZnO glass powder, 2 parts of calcium fluoride, 1 part of ethyl cellulose, 18 parts of pinene alcohol, 3 parts of glycerol, and 0.5 parts of melamine;

[0051] Using anhydrous ethanol as a ball-milling medium, a mixture of Bi2O3, B2O3 and ZnO in a mass ratio of 13.5:3:1 is ball-milled and dried, and then heated to 1350° C. in a crucible for 30 min. The obtained molten liquid is added to deionized water for quenching to obtain initial glass particles, and the initial glass particles are ball-milled again and dried to obtain Bi2O3-B2O3-ZnO glass powder;

[0052] Molybdenum powder, manganese powder, aluminum powder, Bi2O3-B2O3-ZnO glass powder and calcium fluoride are ball-milled in a ball mill for 5 hours. The obtained mixed powder is mixed with ethyl cellulose, pineol, glycerol and melamine, and then put into a vibration mill for vibration grinding for 5 hours. Finally, the metallization slurry is obtained after filtering with a nylon mesh. The metallization slurry is screen-printed onto an alumina ceramic substrate and dried, and then heated to 1450°C in a nitrogen atmosphere and sintered for 2 hours.

[0053] Comparative Example 1:

[0054] The method is basically the same as Example 1, except that no aluminum powder is added.

[0055] Comparative Example 2:

[0056] The method is basically the same as Example 1, except that melamine is not added.

[0057] Comparative Example 3:

[0058] It is basically the same as Example 1, except that yttrium oxide is not added.

[0059] Performance testing:

[0060] When making the test specimens, the alumina ceramic substrates in Examples 1-4 and Comparative Examples 1-3 are replaced by hot die-cast standard tensile parts with a grade of A-95, and a layer of electrodeposited nickel with a thickness of about 4±0.5 μm is electroplated on the surface of the metallized layer by electroplating. The Kovar ring uses a Φ16 mm×10 mm×δ0.5 mm ring with a grade of 4J33, and the solder uses AgCu28 solder. The tensile strength test is carried out with reference to SJ / T3326-2016 "Test Method for Tensile Strength of Ceramic-Metal Seals", and the test results are shown in Table 1 below:

[0061] Table 1:

[0062] ;

[0063] It can be seen from Table 1 above that the test piece prepared by the process of the present invention has a higher tensile strength, and through the comparison between Example 1 and Comparative Examples 1-3, it can be seen that the addition of aluminum powder, melamine and yttrium oxide plays a positive role in improving the tensile strength.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A surface metallization process for an alumina ceramic substrate, characterized in that: The details are as follows: S1: cleaning the alumina ceramic substrate; S2: Prepare metallization slurry, which is made of the following raw materials in parts by weight: 80-100 parts of metal powder, 5-10 parts of glass powder, 1-2 parts of metal fluoride, and 15-30 parts of organic carrier; S3: screen printing the metallization slurry onto the alumina ceramic substrate and drying it, and then sintering it in a nitrogen atmosphere; The metal powder includes molybdenum powder, manganese powder and aluminum powder; The mass ratio of the molybdenum powder, manganese powder and aluminum powder is 70-90:5-10:1-5; The glass powder includes Bi2O3, B2O3 and ZnO; The preparation method of the glass powder is as follows: Using anhydrous ethanol as a ball milling medium, Bi2O3, B2O3 and ZnO are mixed and ball milled, then dried, and then heated to 1300-1400°C in a crucible for 30-60 minutes, and the obtained molten liquid is added to deionized water for quenching to obtain initial glass particles, and the initial glass particles are ball milled again and dried; The mass ratio of Bi2O3, B2O3 and ZnO is 10-15:2-4:1; The metal fluoride is calcium fluoride or yttrium fluoride; The organic carrier comprises ethyl cellulose, terpineol, glycerol and melamine; The sintering temperature is 1350-1550°C.

2. The surface metallization process of the alumina ceramic substrate according to claim 1, characterized in that: The mass ratio of the ethyl cellulose, terpineol, glycerol and melamine is 1:18:3:0.5.

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