A method for preparing a ceramic copper-clad plate by direct writing 3D printing copper paste

Abstract

The application relates to a method for preparing a ceramic copper-clad plate by direct writing 3D printing of copper paste, and relates to a method for preparing a ceramic copper-clad plate. The application aims to solve the problems that traditional ceramic substrate copper-clad technology cannot simultaneously consider low cost, high precision, controllable thickness and simple process, and solve the problem that existing 3D printing copper paste technology cannot simultaneously consider thick copper and precision. The method comprises the following steps: 1, preparation of 3D printing conductive copper paste; 2, direct writing 3D printing of the copper paste; and 3, sintering. The application is used for preparing a ceramic copper-clad plate by direct writing 3D printing of copper paste.

Description

Technical Field

[0001] This invention relates to a method for preparing ceramic copper-clad laminates. Background Technology

[0002] Ceramic-clad copper laminates (CCLs) possess high thermal conductivity, low expansion, excellent mechanical properties, and resistance to chemical corrosion. They are fundamental materials for interconnect and structural technologies in high-power power electronic circuits, improving the efficiency and lifespan of semiconductor chips. Benefiting from their excellent stability, CCLs are widely used in electronic fields requiring high power, high frequency, and high reliability. Major applications include: power semiconductor modules (such as IGBTs and automotive electronics), high-power LED lighting (especially COB packaging), microwave RF devices (base stations, radar), new energy vehicle electronic control systems, aerospace electronic equipment, and semiconductor lasers, providing crucial support for stable heat dissipation and efficient operation of electronic equipment in harsh environments.

[0003] Currently, copper-clad laminate (CCL) technologies for various types of ceramic substrates (TPC / DBC / AMB / DPC, etc.) are limited by issues such as low precision in copper circuit forming, excessively thin forming thickness, high cost, complex fabrication methods, and environmental concerns. TPC substrates have a simple fabrication process, low requirements for processing equipment and environment, and advantages such as high production efficiency and low manufacturing cost; however, due to limitations in screen printing, the thickness of the metal circuit layer fabricated on TPC substrates is generally 10μm~20μm, making it impossible to obtain high-precision circuits (minimum linewidth / spacing is generally greater than 100μm). DBC substrates require strict control of eutectic temperature and oxygen content during fabrication, placing high demands on equipment and process control, resulting in high production costs; furthermore, limitations in thick copper etching prevent the fabrication of high-precision circuit layers. AMB substrates rely on a chemical reaction between active solder and ceramic to achieve bonding, resulting in high bonding strength and good reliability; however, this method is costly, and due to limitations in thick copper etching, it is impossible to fabricate high-precision circuit layers. The metal circuit layer of DPC substrate is prepared by electroplating, which causes serious environmental pollution. In addition, the electroplating growth rate is low and the thickness of the circuit layer is limited (generally controlled at 10μm~100μm), which makes it difficult to meet the packaging requirements of high current power devices.

[0004] Applying 3D printing copper paste technology to the fabrication of ceramic copper-clad laminates (CCLs) enables additive manufacturing of a ceramic substrate and copper circuitry in three-dimensional space, achieving "structural-functional integration." This surpasses the limitations of traditional etching or thick-film printing, which are confined to planar layouts, and offers significant advantages in size, precision, material structure, and process cost. Traditional ceramic copper-clad laminates (such as DPC, DBC, and AMB) involve attaching a copper layer to a pre-fabricated planar ceramic sheet through processes like plating and brazing. The 3D printing approach aims to simultaneously or sequentially manufacture the ceramic substrate and three-dimensional copper circuitry / structures, enabling embedded circuits, three-dimensional heat dissipation channels, and irregularly shaped packaging shells. However, the success of 3D printing copper paste for ceramic copper-clad laminate fabrication heavily relies on the close synergy and optimization of materials (paste), processes (printing), and post-processing (debinding and sintering). A paradoxical relationship exists between copper film thickness and precision: thicker films result in lower precision, while thinner films offer higher precision. Summary of the Invention

[0005] This invention aims to address the problems of traditional ceramic substrate copper cladding technology being unable to simultaneously achieve low cost, high precision, controllable thickness, and simple process, as well as the problem of existing 3D printing copper paste technology being unable to achieve both thick copper and high precision. Therefore, it provides a method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste.

[0006] A method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste, comprising the following steps:

[0007] I. Preparation of 3D Printing Conductive Copper Paste:

[0008] Weigh 15 to 20 parts of organic carrier, 4 to 8 parts of glass powder and 75 to 80 parts of copper powder according to the mass fraction, then stir evenly and remove bubbles by vacuum to obtain conductive copper paste.

[0009] The glass powder is a mixture of Bi2O3, B2O3, SiO2, ZnO and CaO;

[0010] The copper powder is composed of copper powder with a D50 particle size of 0.2μm~0.4μm and copper powder with a D50 particle size of 0.6μm~0.8μm;

[0011] II. Direct Writing 3D Printing with Copper Paste:

[0012] The conductive copper paste is loaded into a dispensing syringe and then used to perform single-layer direct-write 3D printing on a ceramic substrate using a direct-write printer to obtain the printed ceramic copper-clad board.

[0013] III. Sintering:

[0014] The printed ceramic copper-clad board is placed in a vacuum atmosphere sintering furnace for sintering to obtain a direct-write 3D printed ceramic copper-clad board, which completes the method of preparing ceramic copper-clad board from direct-write 3D printed copper paste.

[0015] The surface copper plate pattern of the direct-write 3D printed ceramic copper-clad laminate has a line width of ≥50μm and a thickness of 50μm~300μm.

[0016] The beneficial effects of this invention are:

[0017] 1. Addressing the challenge of achieving a balance between thick copper and high precision in existing 3D printing copper paste technologies, this invention achieves a harmonious coexistence of pattern linewidth, precision, and thick copper. Through synergistic optimization of the rheological properties, shrinkage deformation control, and post-sintering treatment of copper paste for direct-write 3D printing, combined with motion parameters and precision control of 3D printing equipment, the linewidth (≥50μm) and thickness (50μm~300μm) of the pattern on the ceramic copper-clad substrate can be freely adjusted within a given range. This results in a wide range of linewidth, precision, and copper film thickness dimensions, significantly shortening the product production cycle and reducing production costs.

[0018] 2. Compared to traditional ceramic copper-clad laminate (CCL) technology, its advantages are: 1) Simple process. The preparation of CCL substrates using direct-write 3D printing copper paste technology requires only three steps: copper paste preparation, printing, and sintering. It eliminates the need for screen printing, photolithography, development, acid etching, and photoresist stripping, greatly simplifying the process, avoiding environmental pollution, and effectively shortening the preparation time of CCLs by more than two-thirds compared to existing technologies. 2) Low cost. The main cost of using 3D printing technology to prepare CCLs lies in the copper powder. Traditional copper cladding technology wastes most of the copper material after etching, making it a traditional subtractive manufacturing technology. 3D printing, however, is an additive manufacturing technology, effectively saving copper raw materials and reducing material costs. Furthermore, after copper cladding is completed, sintering completes the manufacturing process. This effectively saves on the material and equipment costs associated with custom screen printing and subsequent photolithography, development, etching, or electroplating processes in traditional copper cladding. Therefore, the cost reduction of CCLs prepared using 3D printing technology is significant. 3) Excellent overall performance. The core performance indicators such as pattern accuracy, bonding strength, reliability and heat resistance are equal to or better than those of traditional ceramic copper-clad substrates. The overall performance surpasses that of traditional ceramic copper-clad substrates, demonstrating excellent overall performance. Attached Figure Description

[0019] Figure 1 Viscosity test of the conductive copper paste prepared in step one of Example 1;

[0020] Figure 2 Viscosity test of the conductive copper paste prepared in step one of Example 2;

[0021] Figure 3 Optical microscopy test of the circuit linewidth of the direct-write 3D printed ceramic copper-clad board prepared in Example 1;

[0022] Figure 4 Optical microscope test of the circuit linewidth of the direct-write 3D printed ceramic copper-clad board prepared in Example 2. Detailed Implementation

[0023] Specific Implementation Method 1: This implementation method is a method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste, which is carried out according to the following steps:

[0024] I. Preparation of 3D Printing Conductive Copper Paste:

[0025] Weigh 15 to 20 parts of organic carrier, 4 to 8 parts of glass powder and 75 to 80 parts of copper powder according to the mass fraction, then stir evenly and remove bubbles by vacuum to obtain conductive copper paste.

[0026] The glass powder is a mixture of Bi2O3, B2O3, SiO2, ZnO and CaO;

[0027] The copper powder is composed of copper powder with a D50 particle size of 0.2μm~0.4μm and copper powder with a D50 particle size of 0.6μm~0.8μm;

[0028] II. Direct Writing 3D Printing with Copper Paste:

[0029] The conductive copper paste is loaded into a dispensing syringe and then used to perform single-layer direct-write 3D printing on a ceramic substrate using a direct-write printer to obtain the printed ceramic copper-clad board.

[0030] III. Sintering:

[0031] The printed ceramic copper-clad board is placed in a vacuum atmosphere sintering furnace for sintering to obtain a direct-write 3D printed ceramic copper-clad board, which completes the method of preparing ceramic copper-clad board from direct-write 3D printed copper paste.

[0032] The surface copper plate pattern of the direct-write 3D printed ceramic copper-clad laminate has a line width of ≥50μm and a thickness of 50μm~300μm.

[0033] The beneficial effects of this embodiment are:

[0034] 1. Addressing the issue that existing 3D printing copper paste technology cannot achieve a balance between thick copper and high precision, this implementation method achieves a balance between linewidth, precision, and thick copper in the pattern. Through synergistic optimization of the rheological properties, shrinkage deformation control, and post-sintering treatment of the copper paste used in direct-write 3D printing, combined with the motion parameters and precision control of the 3D printing equipment, the linewidth (≥50μm) and thickness (50μm~300μm) of the pattern on the ceramic copper-clad substrate can be freely adjusted within a given range. This results in a wide range of linewidth, precision, and copper film thickness dimensions, significantly shortening the product production cycle and reducing production costs.

[0035] 2. Compared to traditional ceramic copper-clad laminate (CCL) technology, its advantages are: 1) Simple process. The preparation of CCL substrates using direct-write 3D printing copper paste technology requires only three steps: copper paste preparation, printing, and sintering. It eliminates the need for screen printing, photolithography, development, acid etching, and photoresist stripping, greatly simplifying the process, avoiding environmental pollution, and effectively shortening the preparation time of CCLs by more than two-thirds compared to existing technologies. 2) Low cost. The main cost of using 3D printing technology to prepare CCLs lies in the copper powder. Traditional copper cladding technology wastes most of the copper material after etching, making it a traditional subtractive manufacturing technology. 3D printing, however, is an additive manufacturing technology, effectively saving copper raw materials and reducing material costs. Furthermore, after copper cladding is completed, sintering completes the manufacturing process. This effectively saves on the material and equipment costs associated with custom screen printing and subsequent photolithography, development, etching, or electroplating processes in traditional copper cladding. Therefore, the cost reduction of CCLs prepared using 3D printing technology is significant. 3) Excellent overall performance. The core performance indicators such as pattern accuracy, bonding strength, reliability and heat resistance are equal to or better than those of traditional ceramic copper-clad substrates. The overall performance surpasses that of traditional ceramic copper-clad substrates, demonstrating excellent overall performance.

[0036] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the organic carrier mentioned in step one is obtained by uniformly stirring and vacuum defoaming 80-85 parts by weight of terpineol, 4-8 parts by weight of polyvinyl butyral, 2-4 parts by weight of ethyl cellulose, and 5-10 parts by weight of sodium dodecyl sulfonate. Everything else is the same as in Specific Implementation Method One.

[0037] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the uniform stirring and vacuum degassing are specifically performed according to the following steps: Using a vacuum stirring degassing machine, first, under conditions where the rotational speed ratio is 1:(0.7~1), the rotational speed is 500 r / min~800 r / min, and the vacuum degree is 101 kPa, the process is carried out for 30 s~60 s; then, under conditions where the rotational speed ratio is 1:(0.7~1), the rotational speed is 2200 r / min~2500 r / min, and the vacuum degree is 60 kPa~80 kPa, the process is carried out for 70 s~100 s; finally, under conditions where the rotational speed ratio is 1:(0.7~1), the rotational speed is 1300 r / min~1600 r / min, and the vacuum degree is 30 kPa~50 kPa, the process is carried out for 30 s~60 s. Everything else is the same as in Specific Implementation Method One or Two.

[0038] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: in step one, the mass ratio of Bi₂O₃ to B₂O₃ in the glass powder is 1:(0.3~0.5), the mass ratio of Bi₂O₃ to SiO₂ is 1:(0.3~0.4), the mass ratio of Bi₂O₃ to ZnO is 1:(0.1~0.2), and the mass ratio of Bi₂O₃ to CaO is 1:(0.05~0.1); the D50 particle size of the glass powder in step one is 1μm~2μm, and the purity is ≥99.9%. Everything else is the same as in Specific Implementation Methods One to Three.

[0039] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the copper powder mentioned in step one is composed of 35 to 64 parts by mass of copper powder with a D50 particle size of 0.2 μm to 0.4 μm and 15 to 40 parts by mass of copper powder with a D50 particle size of 0.6 μm to 0.8 μm; the purity of the copper powder mentioned in step one is ≥99.9%. Everything else is the same as in Specific Implementation Methods One to Four.

[0040] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the viscosity of the conductive copper paste described in step one is 200 Pa·s to 300 Pa·s. Everything else is the same as in Specific Implementation Methods One to Five.

[0041] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the ceramic substrate mentioned in step two is an Al2O3 ceramic substrate, a zirconia-toughened alumina ceramic substrate, or a Si3N4 ceramic substrate. Everything else is the same as in Specific Implementation Methods One to Six.

[0042] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the single-layer direct-write 3D printing described in step two is carried out under the following conditions: the inner diameter of the printing needle is 50μm~200μm, the extrusion pressure is 0.2MPa~0.6MPa, the printing speed is 10mm / s~30mm / s, and the printing height of the needle is 10μm~1000μm. Everything else is the same as in Specific Implementation Methods One to Seven.

[0043] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the trajectory movement path during the printing process is a rectangle, an S-path, or a rectangular loop. Everything else is the same as Specific Implementation Methods One to Eight.

[0044] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the sintering described in step three is carried out as follows: Under a vacuum of 30 kPa to 50 kPa, nitrogen protective gas is introduced at a flow rate of 1 L / min to 2 L / min. First, the temperature is increased to 220°C to 250°C at a rate of 1°C / min to 1.5°C / min and held for 2 to 4 hours. Then, the temperature is increased to 400°C to 450°C at a rate of 1°C / min to 1.5°C / min and held for 2 to 4 hours. Next, the temperature is increased to 750°C to 800°C at a rate of 4°C / min to 5°C / min. Finally, the temperature is increased to 850°C to 880°C at a rate of 2°C / min to 3°C / min and held for 15 to 30 minutes. The rest is the same as in Specific Implementation Methods One to Nine.

[0045] The beneficial effects of the present invention are verified using the following embodiments:

[0046] Example 1:

[0047] A method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste, comprising the following steps:

[0048] I. Preparation of 3D Printing Conductive Copper Paste:

[0049] ① Weigh out 82 parts of terpineol, 6 parts of polyvinyl butyral, 2 parts of ethyl cellulose and 10 parts of sodium dodecyl sulfonate according to the mass fractions, then stir evenly and remove bubbles under vacuum to obtain an organic carrier.

[0050] The uniform stirring and vacuum degassing are carried out in the following steps: using a vacuum stirring degassing machine, first, under the conditions of a revolution-to-rotation speed ratio of 1:1, a revolution speed of 500 r / min and a vacuum degree of 101 kPa, the mixture is processed for 60 seconds; then, under the conditions of a revolution-to-rotation speed ratio of 1:1, a revolution speed of 2200 r / min and a vacuum degree of 60 kPa, the mixture is processed for 100 seconds; finally, under the conditions of a revolution-to-rotation speed ratio of 1:1, a revolution speed of 1300 r / min and a vacuum degree of 50 kPa, the mixture is processed for 60 seconds.

[0051] ②Weigh out 19 parts organic carrier, 6 parts glass powder and 75 parts copper powder by mass, then stir evenly and remove bubbles by vacuum to obtain conductive copper paste.

[0052] The uniform stirring and vacuum degassing are carried out in the following steps: using a vacuum stirring degassing machine, first, under the conditions of a revolution-to-rotation speed ratio of 1:1, a revolution speed of 500 r / min and a vacuum degree of 101 kPa, the mixture is processed for 60 seconds; then, under the conditions of a revolution-to-rotation speed ratio of 1:1, a revolution speed of 2200 r / min and a vacuum degree of 60 kPa, the mixture is processed for 100 seconds; finally, under the conditions of a revolution-to-rotation speed ratio of 1:1, a revolution speed of 1300 r / min and a vacuum degree of 50 kPa, the mixture is processed for 60 seconds.

[0053] The glass powder is a mixture of Bi2O3, B2O3, SiO2, ZnO, and CaO; the mass ratio of Bi2O3 to B2O3 in the glass powder is 50:20, the mass ratio of Bi2O3 to SiO2 is 50:20, the mass ratio of Bi2O3 to ZnO is 50:7, and the mass ratio of Bi2O3 to CaO is 50:3; the D50 particle size of the glass powder is 1.5 μm, and the purity is ≥99.9%.

[0054] The copper powder is composed of 60 parts by weight of copper powder with a D50 particle size of 0.3 μm and 15 parts by weight of copper powder with a D50 particle size of 0.8 μm; the purity of the copper powder is ≥99.9%; the viscosity of the conductive copper paste is 286 Pa·s.

[0055] II. Direct Writing 3D Printing with Copper Paste:

[0056] Conductive copper paste was loaded into a dispensing syringe. Using a direct-write printer, single-layer direct-write 3D printing was performed on a ceramic substrate under the conditions of a printing needle inner diameter of 50μm, an extrusion pressure of 0.5MPa, a printing speed of 20mm / s, and a printing needle height of 100μm to obtain the printed ceramic copper-clad laminate.

[0057] The ceramic substrate is an Al2O3 ceramic substrate;

[0058] The trajectory of the movement during the printing process is an S-shaped path;

[0059] III. Sintering:

[0060] The printed ceramic copper-clad board is placed in a vacuum atmosphere sintering furnace for sintering to obtain a direct-write 3D printed ceramic copper-clad board.

[0061] The sintering process is carried out in the following steps: under a vacuum of 30 kPa, nitrogen protective gas is introduced at a flow rate of 1 L / min. The temperature is first increased to 250°C at a rate of 1°C / min and held for 2 hours. Then, the temperature is increased to 450°C at a rate of 1.5°C / min and held for 2 hours. Next, the temperature is increased to 750°C at a rate of 4°C / min. Finally, the temperature is increased to 850°C at a rate of 2°C / min and held for 30 minutes.

[0062] The direct-write 3D printed ceramic copper-clad laminate has a surface copper pattern linewidth of 50μm and a surface copper pattern thickness of 70μm.

[0063] Example 2:

[0064] A method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste, comprising the following steps:

[0065] I. Preparation of 3D Printing Conductive Copper Paste:

[0066] ① Weigh out 84 parts of terpineol, 4 parts of polyvinyl butyral, 4 parts of ethyl cellulose and 8 parts of sodium dodecyl sulfonate according to the mass fraction, then stir evenly and remove bubbles under vacuum to obtain an organic carrier.

[0067] The uniform stirring and vacuum degassing are carried out in the following steps: using a vacuum stirring degassing machine, first, under the conditions of a revolution-to-rotation speed ratio of 1:0.7, a revolution speed of 800 r / min and a vacuum degree of 101 kPa, the mixture is processed for 30 seconds; then, under the conditions of a revolution-to-rotation speed ratio of 1:0.7, a revolution speed of 2500 r / min and a vacuum degree of 60 kPa, the mixture is processed for 70 seconds; finally, under the conditions of a revolution-to-rotation speed ratio of 1:0.7, a revolution speed of 1600 r / min and a vacuum degree of 30 kPa, the mixture is processed for 60 seconds.

[0068] ② Weigh 16 parts organic carrier, 4 parts glass powder and 80 parts copper powder according to the mass fraction, then stir evenly and remove bubbles by vacuum to obtain conductive copper paste;

[0069] The uniform stirring and vacuum degassing are carried out in the following steps: using a vacuum stirring degassing machine, first, under the conditions of a revolution-to-rotation speed ratio of 1:0.7, a revolution speed of 800 r / min and a vacuum degree of 101 kPa, the mixture is processed for 30 seconds; then, under the conditions of a revolution-to-rotation speed ratio of 1:0.7, a revolution speed of 2500 r / min and a vacuum degree of 60 kPa, the mixture is processed for 70 seconds; finally, under the conditions of a revolution-to-rotation speed ratio of 1:0.7, a revolution speed of 1600 r / min and a vacuum degree of 30 kPa, the mixture is processed for 60 seconds.

[0070] The glass powder is a mixture of Bi2O3, B2O3, SiO2, ZnO, and CaO; the mass ratio of Bi2O3 to B2O3 in the glass powder is 50:20, the mass ratio of Bi2O3 to SiO2 is 50:20, the mass ratio of Bi2O3 to ZnO is 50:7, and the mass ratio of Bi2O3 to CaO is 50:3; the D50 particle size of the glass powder is 1 μm, and the purity is ≥99.9%.

[0071] The copper powder is composed of 40 parts by weight of copper powder with a D50 particle size of 0.3 μm and 40 parts by weight of copper powder with a D50 particle size of 0.8 μm; the purity of the copper powder is ≥99.9%; the viscosity of the conductive copper paste is 217 Pa·s.

[0072] II. Direct Writing 3D Printing with Copper Paste:

[0073] Conductive copper paste was loaded into a dispensing syringe. Using a direct-write printer, single-layer direct-write 3D printing was performed on a ceramic substrate under the conditions of a printing needle inner diameter of 150μm, an extrusion pressure of 0.4MPa, a printing speed of 10mm / s, and a printing needle height of 400μm to obtain the printed ceramic copper-clad laminate.

[0074] The ceramic substrate is an Al2O3 ceramic substrate;

[0075] The trajectory of the movement during the printing process is an S-shaped path;

[0076] III. Sintering:

[0077] The printed ceramic copper-clad board is sintered in a vacuum atmosphere sintering furnace to obtain a direct-write 3D printed ceramic copper-clad board.

[0078] The sintering process is carried out in the following steps: under a vacuum of 30 kPa, nitrogen protective gas is introduced at a flow rate of 1 L / min. The temperature is first increased to 250°C at a rate of 1°C / min and held for 2 hours. Then, the temperature is increased to 450°C at a rate of 1°C / min and held for 2 hours. Next, the temperature is increased to 800°C at a rate of 5°C / min. Finally, the temperature is increased to 880°C at a rate of 3°C / min and held for 15 minutes.

[0079] The direct-write 3D printed ceramic copper-clad laminate has a surface copper pattern linewidth of 100μm and a surface copper pattern thickness of 300μm.

[0080] Table 1. Performance of direct-write 3D printed ceramic copper-clad laminates prepared in Examples 1-2

[0081]

[0082] Figure 1 Viscosity test of the conductive copper paste prepared in step one of Example 1; Figure 2The viscosity of the conductive copper paste prepared in step one of Example 2 was tested. As shown in the figure, with increasing shear rate, the viscosity of the copper paste gradually decreases until it stabilizes, exhibiting shear-thinning pseudoplastic fluid characteristics. This indicates that the copper paste has a higher viscosity at low shear and stronger resistance to sedimentation; while at high shear, the lower the viscosity, the easier it is to brush and the less likely brush marks will appear. This demonstrates that the prepared copper paste possesses excellent rheological properties, which is beneficial for high-resolution, high-stability copper circuit printing. During direct-write 3D printing extrusion, the paste is shear-thinned under pressure through a fine nozzle, making it easy to extrude; after extrusion and deposition onto the platform, it immediately regains its high viscosity, enabling it to support its own weight and achieve multi-layer stacking without collapse, which is helpful for manufacturing three-dimensional structures.

[0083] Figure 1 and Figure 2 middle:

[0084] τ — Shear stress, in Pa;

[0085] η — viscosity, in Pa·s;

[0086] Herschel-Bulkley — the standard flow curve model;

[0087] ý — Shear rate, unit: s -1 .

[0088] Figure 3 Optical microscopy test of the circuit linewidth of the direct-write 3D printed ceramic copper-clad board prepared in Example 1; Figure 4 Optical microscopy was used to measure the linewidth of the direct-write 3D printed ceramic copper-clad laminate prepared in Example 2. The figures show that the copper circuit linewidth in Example 1 reaches approximately 50 μm, with a dimensional accuracy deviation within ±5 μm; the copper circuit linewidth in Example 2 reaches 100 μm, with a dimensional accuracy deviation within ±5 μm. These results demonstrate the achievement of high-precision copper-clad circuit fabrication with controllable and adjustable linewidth, exhibiting a high degree of fabrication flexibility.

Claims

1. A method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste, characterized in that... It is done in the following steps: I. Preparation of 3D Printing Conductive Copper Paste: Weigh 15 to 20 parts of organic carrier, 4 to 8 parts of glass powder and 75 to 80 parts of copper powder according to the mass fraction, then stir evenly and remove bubbles by vacuum to obtain conductive copper paste. The glass powder is a mixture of Bi2O3, B2O3, SiO2, ZnO and CaO; The copper powder is composed of copper powder with a D50 particle size of 0.2μm~0.4μm and copper powder with a D50 particle size of 0.6μm~0.8μm; II. Direct Writing 3D Printing with Copper Paste: The conductive copper paste is loaded into a dispensing syringe and then used to perform single-layer direct-write 3D printing on a ceramic substrate using a direct-write printer to obtain the printed ceramic copper-clad board. III. Sintering: The printed ceramic copper-clad board is placed in a vacuum atmosphere sintering furnace for sintering to obtain a direct-write 3D printed ceramic copper-clad board, which completes the method of preparing ceramic copper-clad board from direct-write 3D printed copper paste. The surface copper plate pattern of the direct-write 3D printed ceramic copper-clad laminate has a line width of ≥50μm and a thickness of 50μm~300μm.

2. The method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 1, characterized in that... The organic carrier mentioned in step one is obtained by uniformly stirring and vacuum defoaming 80-85 parts of terpineol, 4-8 parts of polyvinyl butyral, 2-4 parts of ethyl cellulose and 5-10 parts of sodium dodecyl sulfonate.

3. A method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 1 or 2, characterized in that... The uniform stirring and vacuum degassing are specifically carried out according to the following steps: using a vacuum stirring degassing machine, firstly, under the conditions of a revolution-to-rotation speed ratio of 1:(0.7~1), a revolution speed of 500 r / min~800 r / min and a vacuum degree of 101 kPa, the process is carried out for 30 s~60 s; then, under the conditions of a revolution-to-rotation speed ratio of 1:(0.7~1), a revolution speed of 2200 r / min~2500 r / min and a vacuum degree of 60 kPa~80 kPa, the process is carried out for 70 s~100 s; finally, under the conditions of a revolution-to-rotation speed ratio of 1:(0.7~1), a revolution speed of 1300 r / min~1600 r / min and a vacuum degree of 30 kPa~50 kPa, the process is carried out for 30 s~60 s.

4. The method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 1, characterized in that... In step one, the mass ratio of Bi2O3 to B2O3 in the glass powder is 1:(0.3~0.5), the mass ratio of Bi2O3 to SiO2 is 1:(0.3~0.4), the mass ratio of Bi2O3 to ZnO is 1:(0.1~0.2), and the mass ratio of Bi2O3 to CaO is 1:(0.05~0.1); the D50 particle size of the glass powder in step one is 1μm~2μm, and the purity is ≥99.9%.

5. The method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 1, characterized in that... The copper powder mentioned in step one is composed of 35 to 64 parts by mass of copper powder with a D50 particle size of 0.2 μm to 0.4 μm and 15 to 40 parts by mass of copper powder with a D50 particle size of 0.6 μm to 0.8 μm; the purity of the copper powder mentioned in step one is ≥99.9%.

6. The method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 1, characterized in that... The viscosity of the conductive copper paste mentioned in step one is 200 Pa·s to 300 Pa·s.

7. The method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 1, characterized in that... The ceramic substrate mentioned in step two is an Al2O3 ceramic substrate, a zirconia-toughened alumina ceramic substrate, or a Si3N4 ceramic substrate.

8. The method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 1, characterized in that... The single-layer direct-write 3D printing described in step two is specifically carried out under the following conditions: the inner diameter of the printing needle is 50μm~200μm, the extrusion pressure is 0.2MPa~0.6MPa, the printing speed is 10mm / s~30mm / s, and the printing height of the needle is 10μm~1000μm.

9. The method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 8, characterized in that... The trajectory of the movement during the printing process is a rectangle, an S-path, or a rectangular loop.

10. The method for preparing ceramic copper-clad laminates using direct-write 3D printing copper paste according to claim 1, characterized in that... The sintering described in step three is carried out in the following steps: Under a vacuum of 30 kPa to 50 kPa, nitrogen protective gas is introduced at a flow rate of 1 L / min to 2 L / min. The temperature is first increased to 220°C to 250°C at a rate of 1°C to 1.5°C / min and held for 2 to 4 hours. Then, the temperature is increased to 400°C to 450°C at a rate of 1°C to 1.5°C / min and held for 2 to 4 hours. Next, the temperature is increased to 750°C to 800°C at a rate of 4°C to 5°C / min. Finally, the temperature is increased to 850°C to 880°C at a rate of 2°C to 3°C / min and held for 15 to 30 minutes.

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