Preparation process of a metallized ceramic substrate

Abstract

The present invention relates to the technical field of ceramic metallization, and specifically to a preparation process of a metallized ceramic substrate. First, a ceramic substrate containing transition metal oxides is prepared, then a metallized slurry containing ethylene-vinyl alcohol copolymer modified phenolic resin is prepared, and finally, the metallized slurry is printed or coated on the surface of the ceramic substrate, and then dried and sintered. The tensile strength of the metallized layer of the metallized ceramic substrate prepared by the present invention reaches more than 40 MPa, and it has broad application prospects in the fields of LED heat dissipation substrates, ceramic packaging, electronic circuit substrates, semiconductor packaging, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic metallization, and specifically to a preparation process of a metallized ceramic substrate. Background Art

[0002] Ceramic substrates have a series of excellent properties such as high temperature resistance, wear resistance, and good insulation. In actual production, ceramics and metals cannot be directly welded. A metallized layer that is firmly bonded to the ceramics must be prepared on the ceramic surface to achieve welding with other metal devices. This process is the metallization of ceramics, and the metallized layer will directly affect the final performance of the welded body. How to improve the bonding strength between the metallized layer and the ceramic substrate has become the current research focus. Summary of the Invention

[0003] Object of the Invention: Aiming at the above technical problems, the present invention proposes a preparation process of a metallized ceramic substrate.

[0004] The technical solution adopted is as follows:

[0005] A preparation process of a metallized ceramic substrate is as follows:

[0006] S1: Prepare a ceramic substrate containing transition metal oxides;

[0007] S2: Prepare a metallization paste containing ethylene-vinyl alcohol copolymer modified phenolic resin;

[0008] S3: Print or coat the metallization paste on the surface of the ceramic substrate, and then dry and sinter it.

[0009] Further, the ceramic substrate is also subjected to rare earth ion implantation.

[0010] Further, the rare earth ions are lanthanum ions and / or cerium ions.

[0011] Further, in S1, the transition metal oxide is any one or a combination of nickel oxide, cobalt oxide, iron oxide, or zinc oxide.

[0012] Further, the preparation method of the ethylene-vinyl alcohol copolymer modified phenolic resin in S2 is as follows:

[0013] Dissolve the ethylene-vinyl alcohol copolymer in an aqueous phenol solution, then add formaldehyde and sodium hydroxide, stir and react for 1-5 h, and then distill off small molecules under reduced pressure.

[0014] Further, the reaction temperature is 50-70 °C.

[0015] Further, S1 is specifically as follows:

[0016] Mix alumina and transition metal oxide with a mass ratio of 80 - 100:1 - 5, ball - mill them, and then dry to obtain a mixed powder. Use the tape - casting method to obtain a green body, degrease and sinter the green body to obtain a ceramic substrate, and finally perform rare - earth ion implantation on the ceramic substrate.

[0017] Further, in terms of mass percentage, the metallization paste comprises the following components:

[0018] Ethylene - vinyl alcohol copolymer - modified phenolic resin 5 - 10%, ethyl cellulose 1 - 3%, molybdenum powder 35 - 45%, manganese powder 8 - 12%, active agent 10 - 15%, and the balance is terpineol.

[0019] Further, the active agent includes calcium oxide, lanthanum oxide, silicon dioxide, and titanium dioxide;

[0020] The mass ratio of calcium oxide, lanthanum oxide, silicon dioxide, and titanium dioxide is 1 - 5:1 - 5:1 - 5:1 - 5.

[0021] Further, the sintering temperature in S3 is ≥1200 °C.

[0022] Advantages of the present invention:

[0023] The present invention provides a preparation process of a metallized ceramic substrate. Performing rare - earth ion implantation on the ceramic substrate can cause changes in the microstructure of the near - surface region of the ceramic substrate, thereby improving the bonding strength between the ceramic substrate and the metallization layer;

[0024] Ethylene - vinyl alcohol copolymer - modified phenolic resin as an organic binder phase can make the metallization paste reach a suitable viscosity range, so as to adhere well to the surface of the ceramic substrate. In addition, it pyrolyzes during high - temperature sintering and in - situ generates carbon nanotubes at the interface between the ceramic substrate and the metallization layer. The carbon nanotubes can improve the physical bonding effect between the interfaces by forming a multi - scale branched structure, thereby enhancing the bonding strength. Compared with other organic binders, ethylene - vinyl alcohol copolymer - modified phenolic resin has a higher char residue rate. During high - temperature sintering, it can provide more carbon - based structures and generate more carbon nanotubes. The inventor further found that adding transition metal oxide or rare - earth ion implantation to the ceramic substrate can improve the bonding strength between the ceramic substrate and the metallization layer. The reason may be that the transition metal oxide has a certain catalytic effect, promoting the generation of carbon nanotubes during the high - temperature pyrolysis of ethylene - vinyl alcohol copolymer - modified phenolic resin, and the implanted rare - earth ions act as catalytic promoters, further promoting the generation quantity of carbon nanotubes and improving the generation efficiency;

[0025] The active agent in the metallization paste flows and migrates between the interface of the ceramic substrate and the metallization layer during the sintering process, which plays a role in improving wetting, increasing density, reducing the firing temperature, and accelerating the sintering process, and also plays a positive role in improving the bonding strength between the ceramic substrate and the metallization layer;

[0026] The tensile strength of the metallization layer of the metallized ceramic substrate prepared by the present invention reaches more than 40 MPa, and it has broad application prospects in the fields of LED heat dissipation substrates, ceramic packaging, electronic circuit substrates, semiconductor packaging, etc. Description of the Drawings

[0027] Figure 1 It is the SEN diagram of the cross-section when the metallization layer of the sample in Example 1 is pulled off. Detailed Description of the Invention

[0028] For those not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained by purchasing on the market. The technologies not mentioned in the present invention refer to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel tests and adopt the same treatment steps and parameters.

[0029] Example 1:

[0030] A preparation process of a metallized ceramic substrate:

[0031] S1: Alumina and cobalt oxide with a mass ratio of 95:5 are added to a ball milling tank, and anhydrous ethanol is used as the ball milling medium. After mixing and ball milling on a planetary ball mill for 10 h, it is dried to obtain a mixed powder. The raw materials are weighed according to the following weight parts: 56 parts of the mixed powder, 1 part of the dispersant glyceryl trioleate, 16 parts of ethanol, 16 parts of methyl ethyl ketone, 5 parts of polyvinyl butyral, and 6 parts of the plasticizer DBP. First, the mixed powder, the dispersant glyceryl trioleate, ethanol, and methyl ethyl ketone are added to the ball milling tank, and anhydrous ethanol is used as the ball milling medium. After mixing and ball milling on a planetary ball mill for 10 h, polyvinyl butyral and the plasticizer DBP are added, and the mixing and ball milling are continued for 10 h to obtain a casting slurry. The casting slurry is degassed in vacuum for 10 min and then cast and formed on a casting machine. The wet blank with the required thickness is formed by controlling the doctor blade, and then the green blank is obtained after drying. The green blank is heated to 550 °C at a rate of 1 °C / min for debinding for 2 h, and then heated to 1550 °C at a rate of 10 °C / min for sintering for 4 h to obtain a ceramic substrate. Finally, the obtained ceramic substrate is fixed on an ion implanter, and lanthanum ions are uniformly implanted on its surface. The implantation dose is 5×10 17 ions / cm 2 and the vacuum chamber of the ion implanter is maintained at 10 -3 -10 -4Before ion implantation, the ceramic substrate needs to be carefully cleaned with acetone and absolute ethanol and dried between Pa;

[0032] S2: Dissolve 12.2 g of ethylene-vinyl alcohol copolymer in 188 g of 50% aqueous phenol solution, then add 122 g of 37% formaldehyde solution and 0.01 g of sodium hydroxide. After mixing evenly, raise the temperature to 60 °C and stir for 5 h. After the reaction, remove small molecules by vacuum distillation to obtain ethylene-vinyl alcohol copolymer modified phenolic resin. To prepare the metallization paste, by mass percentage, the metallization paste includes the following components: 8% of ethylene-vinyl alcohol copolymer modified phenolic resin, 2% of ethyl cellulose, 40% of molybdenum powder, 8% of manganese powder, 3% of calcium oxide, 3% of lanthanum oxide, 3% of silicon dioxide, 3% of titanium dioxide, and the balance is terpineol. Add molybdenum powder, manganese powder, calcium oxide, lanthanum oxide, silicon dioxide, and titanium dioxide into the ball milling tank, and perform dry ball milling on a planetary ball mill for 36 h. Mix and stir the obtained mixture with ethylene-vinyl alcohol copolymer modified phenolic resin, ethyl cellulose, and terpineol for 1 h. After completion, put it into a vibratory mill and vibrate for 4 h. Finally, filter it through a 400-mesh nylon sieve to obtain the metallization paste;

[0033] S3: Print the metallization paste on the surface of the ceramic substrate through a screen printing machine and dry it at 100 °C. Control the thickness of the metallized layer after drying to be 10 ± 0.5 μm. Then, raise the temperature to 600 °C at a rate of 1 °C / min and hold for 5 h. Finally, raise the temperature to 1350 °C at a rate of 10 °C / min and sinter for 2 h.

[0034] Brazing a 4J33 kovar rod (rod body φ5 mm, welding end φ3 mm) vertically to the center of the metallized layer prepared in this example to obtain a specimen. The solder is an Ag72Cu28 solder sheet. Use a WP500 type tensile testing machine to perform tensile testing on the specimen at a tensile rate of 5 mm / min. Convert the pull-off force when the specimen is pulled off into the bonding strength. The tensile strength of the metallized layer is 57 MPa. See Figure 1 to see the carbon nanotubes in the pull-off section of the metallized layer.

[0035] Example 2:

[0036] It is basically the same as Example 1, except that, by mass percentage, the metallization paste includes the following components: 10% of ethylene-vinyl alcohol copolymer modified phenolic resin, 1% of ethyl cellulose, 45% of molybdenum powder, 8% of manganese powder, 3% of calcium oxide, 3% of lanthanum oxide, 3% of silicon dioxide, 3% of titanium dioxide, and the balance is terpineol.

[0037] A 4J33 Kovar rod (rod body φ5mm, welding end φ3mm) was vertically brazed to the center of the metallization layer prepared in this example to obtain a specimen. The solder was an Ag72Cu28 solder sheet. A WP500 type tensile testing machine was used to stretch the specimen at a stretching rate of 5mm / min. The pull-off force when the specimen was pulled off was converted into the bonding strength, and the tensile strength of the metallization layer was 54MPa.

[0038] Example 3:

[0039] Basically the same as Example 1, the difference is that, by mass percentage, the metallization paste includes the following components: ethylene-vinyl alcohol copolymer modified phenolic resin 5%, ethyl cellulose 3%, molybdenum powder 35%, manganese powder 12%, calcium oxide 3%, lanthanum oxide 3%, silicon dioxide 3%, titanium dioxide 3%, and the balance is terpineol.

[0040] A 4J33 Kovar rod (rod body φ5mm, welding end φ3mm) was vertically brazed to the center of the metallization layer prepared in this example to obtain a specimen. The solder was an Ag72Cu28 solder sheet. A WP500 type tensile testing machine was used to stretch the specimen at a stretching rate of 5mm / min. The pull-off force when the specimen was pulled off was converted into the bonding strength, and the tensile strength of the metallization layer was 49MPa.

[0041] Example 4:

[0042] Basically the same as Example 1, the difference is that cerium ion implantation treatment was used instead of lanthanum ion implantation treatment.

[0043] A 4J33 Kovar rod (rod body φ5mm, welding end φ3mm) was vertically brazed to the center of the metallization layer prepared in this example to obtain a specimen. The solder was an Ag72Cu28 solder sheet. A WP500 type tensile testing machine was used to stretch the specimen at a stretching rate of 5mm / min. The pull-off force when the specimen was pulled off was converted into the bonding strength, and the tensile strength of the metallization layer was 44MPa.

[0044] Comparative Example 1:

[0045] Basically the same as Example 1, the difference is that the ceramic substrate was not subjected to lanthanum ion implantation treatment during preparation.

[0046] A 4J33 Kovar rod (rod body φ5mm, welding end φ3mm) was vertically brazed to the center of the metallization layer prepared in this example to obtain a specimen. The solder was an Ag72Cu28 solder sheet. A WP500 type tensile testing machine was used to stretch the specimen at a stretching rate of 5mm / min. The pull-off force when the specimen was pulled off was converted into the bonding strength, and the tensile strength of the metallization layer was 41MPa.

[0047] Comparative Example 2:

[0048] Basically the same as Example 1, except that cobalt oxide is not added during the preparation of the ceramic substrate.

[0049] A 4J33 Kovar bar (bar body φ5mm, welding end φ3mm) was vertically brazed to the center of the metallization layer prepared in this example to obtain a specimen. The solder was an Ag72Cu28 solder sheet. A WP500 type tensile testing machine was used to perform tensile tests on the specimens at a tensile rate of 5mm / min. The tensile force at the moment when the specimen was pulled off was converted into the bonding strength, and the tensile strength of the metallization layer was 34MPa.

[0050] Comparative Example 3:

[0051] Basically the same as Example 1, except that polyvinyl butyral is used to replace ethylene-vinyl alcohol copolymer modified phenolic resin.

[0052] A 4J33 Kovar bar (bar body φ5mm, welding end φ3mm) was vertically brazed to the center of the metallization layer prepared in this example to obtain a specimen. The solder was an Ag72Cu28 solder sheet. A WP500 type tensile testing machine was used to perform tensile tests on the specimens at a tensile rate of 5mm / min. The tensile force at the moment when the specimen was pulled off was converted into the bonding strength, and the tensile strength of the metallization layer was 30MPa.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing a metallized ceramic substrate, characterized in that: The details are as follows: S1: preparing a ceramic substrate containing a transition metal oxide; S2: preparing a metallization slurry containing ethylene-vinyl alcohol copolymer modified phenolic resin; S3: printing or coating the metallization slurry on the surface of the ceramic substrate, followed by drying and sintering; The ceramic substrate is also implanted with rare earth ions; The transition metal oxide in S1 is any one or more combinations of nickel oxide, cobalt oxide, iron oxide or zinc oxide; The rare earth ions are lanthanum ions and / or cerium ions; The metallization paste comprises the following components in percentage by mass: 5-10% of ethylene-vinyl alcohol copolymer modified phenolic resin, 1-3% of ethyl cellulose, 35-45% of molybdenum powder, 8-12% of manganese powder, 10-15% of active agent, and the balance is pinene alcohol; The active agents include calcium oxide, lanthanum oxide, silicon dioxide and titanium dioxide.

2. The process for preparing a metallized ceramic substrate according to claim 1, characterized in that: The preparation method of the ethylene-vinyl alcohol copolymer modified phenolic resin described in S2 is as follows: Dissolve ethylene-vinyl alcohol copolymer in phenol aqueous solution, add formaldehyde and sodium hydroxide, stir to react for 1-5 hours, and then distill under reduced pressure to remove small molecules.

3. The process for preparing the metallized ceramic substrate according to claim 2, characterized in that: The reaction temperature is 50-70°C.

4. The process for preparing a metallized ceramic substrate according to claim 1, characterized in that: S1 is as follows: Alumina and transition metal oxides in a mass ratio of 80-100:1-5 are mixed and ball-milled and then dried to obtain a mixed powder, a green body is obtained by a tape casting method, the green body is debinded and sintered to obtain a ceramic substrate, and finally the ceramic substrate is implanted with rare earth ions.

5. The process for preparing a metallized ceramic substrate according to claim 1, characterized in that: The mass ratio of the calcium oxide, lanthanum oxide, silicon dioxide and titanium dioxide is 1-5:1-5:1-5:1-5.

6. The process for preparing a metallized ceramic substrate according to claim 1, characterized in that: The sintering temperature in S3 is ≥1200°C.

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