An Isostatic Pressing Method for Alumina Ceramic Substrate

Abstract

This invention relates to the field of alumina ceramic substrate technology, specifically to an isostatic pressing method for alumina ceramic substrate materials. The invention involves coating copper powder with paraffin wax on the inner wall of an isostatic pressing mold. During the forming process of the alumina ceramic substrate material, the high temperature generated during isostatic pressing melts the paraffin wax, allowing the copper powder to be stably and uniformly adhered to the surface of the alumina under pressure. This achieves simultaneous isostatic pressing and copper plating of the alumina ceramic substrate material. Furthermore, during the subsequent heating process, the high temperature hardens the alumina ceramic substrate material and allows copper metal to oxidize and diffuse into the interior of the alumina ceramic substrate, forming a eutectic melt, thus improving the performance of the alumina ceramic substrate material and effectively increasing the production efficiency of alumina ceramic substrate materials.

Description

Technical Field

[0001] This invention relates to an isostatic pressing method, specifically an isostatic pressing method for alumina ceramic substrate materials. Background Technology

[0002] Ceramic substrates, also known as ceramic base plates, are sheet-like materials based on electronic ceramics, forming a supporting base for film circuit components and externally mounted components. Ceramic substrates possess major advantages such as high temperature resistance, high electrical insulation, low dielectric constant and dielectric loss, high thermal conductivity, good chemical stability, and a coefficient of thermal expansion similar to that of the components. However, ceramic substrates are relatively brittle, resulting in smaller substrate areas and higher costs. Among them, alumina ceramic substrates are the most widely used ceramic substrates due to their relatively simple manufacturing process, lower cost, and lower price.

[0003] In the production of alumina ceramic substrates, there are various forming methods for alumina ceramic products, including dry stamping, slurry injection, stamping, cold isostatic pressing, injection molding, tape casting, hot pressing, and hot isostatic pressing. The principle of alumina isostatic pressing is to use high pressure to fully compact alumina powder, forming a dense bond between the particles, thereby increasing the density and strength of the ceramic product. In the isostatic pressing process, alumina powder is placed in a mold, and then high pressure is applied to shape it into the desired form. Subsequently, through a sintering process, the alumina powder is sintered into a hard ceramic product.

[0004] However, alumina ceramic substrates require metal plating on their surface for practical use to achieve better properties. The existing isostatic pressing method necessitates multiple sintering operations to meet the required performance, significantly increasing manufacturing time and reducing efficiency. Therefore, this invention proposes an isostatic pressing method for alumina ceramic substrates to address these issues. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an isostatic pressing method for alumina ceramic substrate materials.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for isostatic pressing of alumina ceramic substrate material includes the following steps:

[0008] S1: Preparation of raw materials: Select alumina powder with a purity of 99.99% as the substrate material and metallic copper powder;

[0009] S2: Design and fabrication of isostatic pressing molds for alumina ceramic substrates;

[0010] S3: Apply adhesive to the inner wall of the completed isostatic pressing mold, and apply metallic copper powder to the inner wall of the isostatic pressing mold, ensuring that the metallic copper powder is completely covered with the inner wall of the isostatic pressing mold;

[0011] S4: After the copper powder and the isostatic pressing mold are firmly bonded, add the specified amount of alumina powder into the inner cavity of the isostatic pressing mold and then seal the isostatic pressing mold.

[0012] S5: Place the isostatic pressing mold containing the raw material into the isostatic pressing equipment to perform isostatic pressing molding operation on alumina.

[0013] S6: After the alumina powder is formed, the isostatic pressing mold is removed from the isostatic pressing equipment, and the formed alumina ceramic substrate material is removed from the isostatic pressing mold. At this time, the alumina ceramic substrate is covered with a layer of metallic copper powder.

[0014] S7: Perform a high-temperature treatment on the alumina ceramic substrate to allow the copper powder to diffuse into the interior of the alumina ceramic substrate and harden the alumina ceramic substrate, thus completing the processing operation of the alumina ceramic substrate.

[0015] As a preferred embodiment of the present invention, the pretreatment operation of the alumina powder raw material in step 1 includes the following steps:

[0016] S11: Add 99.99% pure alumina powder into the mixing equipment;

[0017] S12: Add lubricant stearic acid and binder polyvinyl alcohol into the mixing equipment, with the lubricant stearic acid and binder polyvinyl alcohol accounting for 2% of the total weight;

[0018] S13: The alumina powder is stirred by a stirring device to ensure that the lubricant stearic acid and the binder polyvinyl alcohol are fully mixed into the alumina powder.

[0019] S14: Pour out the fully mixed alumina powder and grind it using a grinding device to make the particle size of the alumina powder less than 1 micrometer, thus completing the pretreatment operation of the alumina powder.

[0020] As a preferred technical solution of the present invention, the adhesive used in step 3 is paraffin wax. The paraffin wax adhesive can be directly applied to the inner wall of the isostatic pressing mold or a thin film can be laid on the inner wall of the isostatic pressing mold, and then the paraffin wax adhesive can be applied on the film.

[0021] As a preferred embodiment of the present invention, in step 4, the thickness of the copper powder on the inner wall of the isostatic pressing mold is in the range of 0.35 micrometers to 0.7 micrometers, and it is necessary to ensure that the copper powder and the isostatic pressing mold are completely and uniformly coated.

[0022] As a preferred embodiment of the present invention, the isostatic pressing medium used in step 5 is water, and the pressure range during the isostatic pressing operation on alumina powder is 100-600 MPa.

[0023] As a preferred embodiment of the present invention, step 7, which involves performing a high-temperature treatment on the alumina ceramic substrate, includes the following steps:

[0024] S71: Place the formed alumina ceramic substrate into the heating equipment and add nitrogen gas into the heating equipment;

[0025] S72: Temperature is increased by heating equipment. When the internal temperature of the heating equipment reaches 1300-1350 degrees Celsius, heating is stopped and the internal pressure of the heating equipment is maintained at 30 MPa for 10 minutes.

[0026] S73: Cool the heating equipment to maintain the internal temperature at 1090-1100 degrees Celsius for 30 minutes;

[0027] S74: Turn off the heating equipment and remove the alumina ceramic substrate material. At this time, the copper metal diffuses into the interior of the alumina ceramic substrate due to high temperature oxidation to form a eutectic melt, completing the copper coating and hardening process of the alumina ceramic substrate material.

[0028] This invention provides an isostatic pressing method for alumina ceramic substrate materials, which has the following beneficial effects:

[0029] 1. This invention uses isostatic pressing to process alumina ceramic substrate materials, which can produce alumina ceramic substrate materials with high density and uniformity, and which are not easily deformed. This effectively improves the consolidation degree of alumina ceramic substrate materials, increases the mechanical properties of alumina ceramic substrate materials, and is convenient and quick to operate, thus improving the efficiency of molding and processing.

[0030] 2. This invention involves coating copper powder with paraffin wax on the inner wall of an isostatic pressing mold. During the molding process of the alumina ceramic substrate, the high temperature generated during isostatic pressing melts the paraffin wax, allowing the copper powder to be stably and uniformly adhered to the surface of the alumina under pressure. This achieves simultaneous isostatic pressing and copper plating of the alumina ceramic substrate. Furthermore, during the subsequent heating process, the high temperature hardens the alumina ceramic substrate and allows copper metal to oxidize and diffuse into the interior of the alumina ceramic substrate, forming a eutectic melt, thus improving the performance of the alumina ceramic substrate and effectively increasing the production efficiency of alumina ceramic substrates. Attached Figure Description

[0031] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0032] Figure 1 This is a flowchart of an isostatic pressing method for alumina ceramic substrate material according to the present invention;

[0033] Figure 2 This is a flowchart of the pretreatment operation of alumina powder raw material in the isostatic pressing method of alumina ceramic substrate material of the present invention.

[0034] Figure 3 This is a flowchart of the high-temperature treatment operation of the alumina ceramic substrate in the isostatic pressing method of the alumina ceramic substrate material of the present invention. Detailed Implementation

[0035] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0036] Example: Figure 1-3 As shown, an isostatic pressing method for alumina ceramic substrate material includes the following steps:

[0037] S1: Preparation of raw materials: Select alumina powder with a purity of 99.99% as the substrate material and metallic copper powder;

[0038] The pretreatment of alumina powder raw materials includes the following steps:

[0039] S11: Add 99.99% pure alumina powder into the mixing equipment;

[0040] S12: Add lubricant stearic acid and binder polyvinyl alcohol into the mixing equipment, with the lubricant stearic acid and binder polyvinyl alcohol accounting for 2% of the total weight;

[0041] S13: The alumina powder is stirred by a stirring device to ensure that the lubricant stearic acid and the binder polyvinyl alcohol are fully mixed into the alumina powder.

[0042] S14: Pour out the fully mixed alumina powder and grind it using a grinding device to make the particle size of the alumina powder less than 1 micrometer, thus completing the pretreatment operation of the alumina powder.

[0043] S2: Design and fabrication of isostatic pressing molds for alumina ceramic substrates;

[0044] S3: Apply adhesive to the inner wall of the completed isostatic pressing mold, and then apply metallic copper powder to the inner wall of the isostatic pressing mold, ensuring complete coverage between the metallic copper powder and the inner wall of the isostatic pressing mold. Paraffin wax is used as the adhesive because the internal temperature of the isostatic pressing mold will rise to 90 degrees Celsius during the isostatic pressing process. At this time, the paraffin wax will melt under the high temperature, reducing the impact on the isostatic pressing of alumina. The paraffin wax adhesive can be applied directly to the inner wall of the isostatic pressing mold or a thin film can be laid on the inner wall of the isostatic pressing mold, and then the paraffin wax adhesive can be applied on the film to avoid the paraffin wax affecting the isostatic pressing mold.

[0045] S4: After the copper powder is firmly bonded to the isostatic pressing mold, add the specified amount of alumina powder into the inner cavity of the isostatic pressing mold. The thickness of the copper powder on the inner wall of the isostatic pressing mold should be in the range of 0.35 micrometers to 0.7 micrometers. It is necessary to ensure that the copper powder is completely and evenly coated with the isostatic pressing mold, and to ensure that the thickness of the copper powder has a certain margin to avoid the influence of external factors on the subsequent copper plating. Then, seal the isostatic pressing mold.

[0046] S5: Place the isostatic pressing mold containing the raw material into the isostatic pressing equipment to perform isostatic pressing molding operation on alumina. The isostatic pressing medium used is water, and the pressure range during the isostatic pressing operation on alumina powder is 500MPa.

[0047] S6: After the alumina powder is formed, the isostatic pressing mold is removed from the isostatic pressing equipment, and the formed alumina ceramic substrate material is removed from the isostatic pressing mold. At this time, the alumina ceramic substrate is covered with a layer of metallic copper powder.

[0048] S7: Perform high-temperature treatment on the alumina ceramic substrate to allow the copper powder to diffuse into the interior of the alumina ceramic substrate and harden the alumina ceramic substrate, thus completing the processing operation of the alumina ceramic substrate.

[0049] The high-temperature treatment of alumina ceramic substrates includes the following steps:

[0050] S71: Place the formed alumina ceramic substrate into the heating equipment and add nitrogen gas into the heating equipment;

[0051] S72: Temperature is increased by heating equipment. When the internal temperature of the heating equipment reaches 1350 degrees Celsius, heating is stopped and the internal pressure of the heating equipment is maintained at 30 MPa for 10 minutes.

[0052] S73: Cool the heating equipment to maintain the internal temperature at 1100 degrees Celsius for 30 minutes;

[0053] S74: Turn off the heating equipment and remove the alumina ceramic substrate material. At this time, the copper metal diffuses into the interior of the alumina ceramic substrate due to high temperature oxidation to form a eutectic melt, completing the copper coating and hardening process of the alumina ceramic substrate material.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for isostatic pressing of alumina ceramic substrate material, comprising the following steps, characterized in that: S1: Preparation of raw materials: Select alumina powder with a purity of 99.99% as the substrate material and metallic copper powder; S2: Design and fabrication of isostatic pressing molds for alumina ceramic substrates; S3: Apply adhesive to the inner wall of the completed isostatic pressing mold, and apply metallic copper powder to the inner wall of the isostatic pressing mold, ensuring that the metallic copper powder is completely covered with the inner wall of the isostatic pressing mold. The adhesive used is paraffin wax. S4: After the copper powder is firmly bonded to the isostatic pressing mold, add the specified amount of alumina powder into the inner cavity of the isostatic pressing mold and seal the isostatic pressing mold. The thickness of the copper powder on the inner wall of the isostatic pressing mold should be in the range of 0.35 micrometers to 0.7 micrometers, and it is necessary to ensure that the copper powder is completely and evenly coated with the isostatic pressing mold. S5: Place the isostatic pressing mold containing the raw material into the isostatic pressing equipment to perform isostatic pressing molding operation on alumina. S6: After the alumina powder is formed, the isostatic pressing mold is removed from the isostatic pressing equipment, and the formed alumina ceramic substrate material is removed from the isostatic pressing mold. At this time, the alumina ceramic substrate is covered with a layer of metallic copper powder. S7: Perform high-temperature treatment on the alumina ceramic substrate to allow the copper powder to diffuse into the interior of the alumina ceramic substrate and harden the alumina ceramic substrate, thus completing the processing operation of the alumina ceramic substrate. The high-temperature treatment of alumina ceramic substrates includes the following steps: S71: Place the formed alumina ceramic substrate into the heating equipment and add nitrogen gas into the heating equipment; S72: Temperature is increased by heating equipment. When the internal temperature of the heating equipment reaches 1300-1350 degrees Celsius, heating is stopped and the internal pressure of the heating equipment is maintained at 30 MPa for 10 minutes. S73: Cool the heating equipment to maintain the internal temperature at 1090-1100 degrees Celsius for 30 minutes; S74: Turn off the heating equipment and remove the alumina ceramic substrate material. At this time, the copper metal diffuses into the interior of the alumina ceramic substrate due to high temperature oxidation to form a eutectic melt, completing the copper coating and hardening process of the alumina ceramic substrate material.

2. The isostatic pressing method for alumina ceramic substrate material according to claim 1, characterized in that, The pretreatment of alumina powder raw materials in step 1 includes the following steps: S11: Add 99.99% pure alumina powder into the mixing equipment; S12: Add stearic acid lubricant and polyvinyl alcohol binder into the mixing equipment, with the stearic acid lubricant and polyvinyl alcohol binder accounting for 2% of the total weight; S13: The alumina powder is stirred by a stirring device to ensure that the lubricant stearic acid and the binder polyvinyl alcohol are fully mixed into the alumina powder. S14: Pour out the fully mixed alumina powder and grind it using a grinding device to make the particle size of the alumina powder less than 1 micrometer, thus completing the pretreatment operation of the alumina powder.

3. The isostatic pressing method for alumina ceramic substrate material according to claim 1, characterized in that, In step 3, the paraffin adhesive can be directly applied to the inner wall of the isostatic pressing mold or a thin film can be laid on the inner wall of the isostatic pressing mold, and then the paraffin adhesive can be applied to the film.

4. The isostatic pressing method for alumina ceramic substrate material according to claim 1, characterized in that, The isostatic pressing medium used in step 5 is water, and the pressure range during the isostatic pressing operation on alumina powder is 100-600 MPa.

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