A method of screen printing a metalized paste

Abstract

The application discloses a method for screen printing a metalized paste, comprising the following steps: step S1: homogenizing and defoaming activation of the metalized paste in sequence to obtain the activated metalized paste; step S2: screen printing the activated metalized paste in step S1 on a surface to be sealed of a ceramic material, controlling the thickness of each screen printing to be not more than 50 microns, and screen printing to the set thickness through multiple times to obtain the ceramic material containing the metalized paste layer; and step S3: sintering the ceramic material containing the metalized paste layer in step S2 to obtain the ceramic material containing the metalized layer. In the method, the thickness of screen printing is controlled, so that the surface of the metalized paste layer after screen printing is prevented from being prone to defects such as grooves and cracks, and thus the quality of metal-ceramic sealing is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic metallization, and particularly relates to a method for screen printing a metallization paste. BACKGROUND

[0002] Metal-ceramic seals are widely used in many fields such as electronics, electric power, aerospace, automobile manufacturing, medical devices, and new energy. Effective sealing between metal and ceramic is crucial for improving the performance and reliability of products, especially in some special application scenarios such as fuel cells, aerospace engines, ion beam sources, and vacuum heating furnaces. These sealing components need to maintain stable performance at high temperatures and withstand temperature shocks from high temperatures to room temperatures. Therefore, higher requirements are placed on the quality of the metallization layer of the sealing component. Due to the large difference in the thermal expansion coefficients of ceramic and metal, in order to reduce the impact of high temperature and temperature changes on the performance of the sealing component, the thickness of the metallization layer of the sealing component is usually increased (generally between 25-50 μm). However, the increase in the thickness of the metallization layer leads to an increase in the screen printing thickness, which makes the metallization paste layer prone to defects. Especially when the size of the ceramic surface to be printed in a certain direction is less than 5 mm and the screen printing thickness exceeds 50 μm, the surface of the metallization paste layer is prone to defects such as grooves and pits, which reduces the quality and reliability of the metal-ceramic seal. SUMMARY

[0003] The purpose of the present application is to provide a method for screen printing a metallization paste, which can effectively improve the surface condition of the metallization paste layer and improve the quality of the metal-ceramic seal.

[0004] In a first aspect, the present application provides a method for screen printing a metallization paste, which adopts the following technical solution:

[0005] A method for screen printing a metallization paste, comprising the following steps:

[0006] Step S1: homogenizing and defoaming and activating the metallization paste in sequence to obtain an activated metallization paste;

[0007] Step S2: screen printing the activated metallization paste in step S1 on the surface of the ceramic material to be sealed, controlling the thickness of each screen printing to be not more than 50 μm, and screen printing multiple times to reach the set thickness; obtaining a ceramic material containing a metallization paste layer;

[0008] Step S3: sintering the ceramic material containing the metallization paste layer in step S2 to obtain a ceramic material containing a metallization layer.

[0009] Preferably, in step S1, the homogenization is carried out under vacuum conditions, and the vacuum degree is-120~-90 KPa.

[0010] Preferably, in the step S1, the rotating speed of the homogenizer is 1200-1600 r / min, and the homogenizing time is 10-15 min.

[0011] Preferably, in the step (1), the defoaming is performed by ultrasonic defoaming.

[0012] Further preferably, the frequency of the ultrasonic defoaming is 40-80 KHz, and the ultrasonic defoaming time is 10-15 min.

[0013] Preferably, in the step S2, the process parameters of the screen printing include: a screen mesh of 80-350 meshes, a wire diameter of 20-45 μm, and a screen distance of 2-4 mm.

[0014] Preferably, in the step S2, the process parameters of the screen printing include: a squeegee angle of 45-85°, a downstroke of 28-35 μm, and a printing speed of 30-100 mm / s.

[0015] Preferably, in the step S2, the thickness of each screen printing is controlled to be 25-50 μm.

[0016] Preferably, in the step S2, after each screen printing, drying is performed; and the drying temperature is 100-130 °C.

[0017] Preferably, in the step S2, the thickness is set to be 55-110 μm.

[0018] Preferably, in the step S3, the sintering temperature is 1400-1600 °C, and the sintering holding time is 0.5-1.5 h.

[0019] The beneficial effects of the present application are as follows:

[0020] (1) In the method of the present application, the thickness of the screen printing is controlled to avoid the defects such as grooves and cracks on the surface of the metallized layer after the screen printing, thereby improving the quality and reliability of the metal-ceramic sealing.

[0021] (2) The method of the present application performs homogenization, defoaming and activation on the metallized paste, which can effectively improve the quality of the metallized paste and improve the quality and reliability of the metal-ceramic sealing. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 An enlarged physical diagram of the ceramic material containing the metallized paste layer prepared in Example 1.

[0023] Figure 2 An enlarged physical diagram of the ceramic material containing the metallized paste layer prepared in Comparative Example 1.

[0024] Figure 3An enlarged photograph of the ceramic material containing the metallized paste layer prepared for Comparative Example 2. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present application, the following will make a more comprehensive and detailed description of the present application in combination with the drawings of the specification and the preferred embodiments, but the protection scope of the present application is not limited to the following specific embodiments.

[0026] Unless otherwise defined, all the professional terms used in the following have the same meaning as that generally understood by the person skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the present application.

[0027] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by the existing method.

[0028] The metallized paste used in the embodiments of the present application is purchased from WINNER TECHNOLOGY Co., Ltd. and the model is WT-MMSM.

[0029] Example 1

[0030] (1) The metallized paste is homogenized by a homogenizer under vacuum conditions, wherein the homogenization rotation speed is 1300 r / min, the homogenization time is 10 min, and the vacuum degree is controlled to be -100 KPa during homogenization, to obtain the homogenized metallized paste. The homogenized metallized paste is placed in an ultrasonic defoaming machine for defoaming, wherein the ultrasonic frequency is 80 KHz and the defoaming time is 10 min, to obtain the activated metallized paste.

[0031] (2) The activated metallization paste is printed on the ceramic surface to be sealed by 2 times of screen printing (the width of the ceramic surface to be sealed is 3 mm). The process parameters of the first time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 200 mesh, the wire diameter is 30 μm, the mesh distance is 2 mm, the doctor blade angle is 60°, the downstroke is 32 μm, the printing speed is 40 mm / s, and the screen printing thickness is 28 μm. After the first time of screen printing, the printed ceramic is placed in an oven and dried at 110°C for 30 min. Then, the second time of screen printing is performed, and the process parameters of the second time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 200 mesh, the wire diameter is 30 μm, the mesh distance is 2 mm, the doctor blade angle is 60°, the downstroke is 32 μm, the printing speed is 40 mm / s, and the screen printing thickness is 31 μm. After the second time of screen printing, the second printed ceramic is placed in an oven and dried at 110°C for 30 min. After drying, the ceramic material containing a metallization paste layer is obtained. The total thickness of the metallization paste layer is 59 μm.

[0032] (3) The ceramic material containing a metallization paste layer obtained in step (2) is placed in a metallization furnace and subjected to metallization sintering at 1500°C for 1 h to obtain a ceramic material containing a metallization layer. The thickness of the metallization layer is about 25 μm.

[0033] The actual photograph of the ceramic material containing a metallization paste layer obtained in step (2) of the example is shown in Figure 1 It can be seen that the metallization paste layer is free of cracks, grooves, and pits.

[0034] Comparative Example 1

[0035] The example is basically the same as example 1, except that the process of screen printing in step 2 is different, and the details are as follows:

[0036] (2) The activated metallization paste is printed on the ceramic surface to be sealed by 1 time of screen printing (the width of the ceramic surface to be sealed is 3 mm). The process parameters of the first time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 100 mesh, the wire diameter is 40 μm, the mesh distance is 3 mm, the doctor blade angle is 60°, the downstroke is 32 μm, the printing speed is 40 mm / s, and the screen printing thickness is 59 μm. After the first time of screen printing, the printed ceramic is placed in an oven and dried at 110°C for 30 min. The ceramic material containing a metallization paste layer is obtained. The total thickness of the metallization paste layer is 59 μm.

[0037] The actual photograph of the ceramic material containing a metallization paste layer obtained in step (2) of the comparative example is shown in Figure 2As shown in FIG. 2, it can be seen that there is an obvious groove in the middle of the metallized paste layer.

[0038] Comparative Example 2

[0039] The same as Example 1, except that the activation process in step (1) is different, as follows:

[0040] (1) The metallized paste was stirred at 25°C using a slurry stirrer at a speed of 300 r / min for 1 h to obtain an activated metallized paste.

[0041] The ceramic material containing the metallized paste layer obtained in step (2) of the present comparative example is shown in FIG. 3. Figure 3 As shown in FIG. 3, it can be seen that there are obvious pits on the surface of the metallized paste layer.

[0042] Comparative Example 3

[0043] The same as Example 1, except that the screen printing process in step 2 is different, as follows:

[0044] (2) The activated metallized paste was printed on the ceramic surface to be sealed (the width of the ceramic surface to be sealed was 3 mm) by one-time screen printing. The process parameters of one-time screen printing were as follows: the ambient temperature was 22-26°C, the humidity was 30-50%, the screen mesh was 200 mesh, the wire diameter was 30 μm, the screen distance was 2 mm, the doctor blade angle was 60°, the downstroke travel was 32 μm, the printing speed was 40 mm / s, and the screen printing thickness was 28 μm. The surface of the metallized paste layer had no cracks, grooves, pits and other defects.

[0045] The metallized layer of the ceramic material containing the metallized layer prepared in the present comparative example had a thickness of about 12 μm.

[0046] Example 2

[0047] (1) The metallized paste was homogenized by a homogenizer under vacuum conditions, wherein the homogenization speed was 1600 r / min, the homogenization time was 10 min, and the vacuum degree was controlled at -90 KPa during homogenization to obtain a homogenized metallized paste. The homogenized metallized paste was placed in an ultrasonic debubbling machine for debubbling, wherein the ultrasonic frequency was 80 KHz, and the debubbling time was 10 min to obtain an activated metallized paste.

[0048] (2) The activated metallized paste is printed on the ceramic surface to be sealed by two times of screen printing. The process parameters of the first time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 165 mesh, the wire diameter is 25 μm, the screen distance is 4 mm, the doctor blade angle is 45°, the downstroke is 35 μm, the printing speed is 50 mm / s, and the screen printing thickness is 32 μm. After the first time of screen printing, the printed ceramic is placed in an oven and dried at 110°C for 30 min. Then, the second time of screen printing is performed. The process parameters of the second time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 165 mesh, the wire diameter is 25 μm, the screen distance is 4 mm, the doctor blade angle is 45°, the downstroke is 35 μm, the printing speed is 50 mm / s, and the screen printing thickness is 38 μm. After the second time of screen printing, the second printed ceramic is placed in an oven and dried at 110°C for 30 min. After drying, the ceramic material containing a metallized paste layer is obtained. The total thickness of the metallized paste layer is 70 μm, and the surface of the metallized paste layer is free of cracks, grooves, and pits.

[0049] (3) The ceramic material containing the metallized paste layer is placed in a metallization furnace and subjected to metallization sintering at 1400°C for 1.5 h to obtain a ceramic material containing a metallized layer. The thickness of the metallized layer is about 29 μm.

[0050] Example 3

[0051] (1) The metallized paste is homogenized by a homogenizer under vacuum conditions. The homogenization speed is 1200 r / min, the homogenization time is 12 min, and the vacuum degree is controlled at -90 KPa during homogenization. The homogenized metallized paste is placed in an ultrasonic debubbling machine for debubbling. The ultrasonic frequency is 40 KHz, and the debubbling time is 15 min. The activated metallized paste is obtained.

[0052] (2) The activated metallized paste is printed on the ceramic surface to be sealed by two times of screen printing. The process parameters of the first time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 300 mesh, the wire diameter is 45 μm, the screen distance is 2 mm, the doctor blade angle is 75°, the down pressure stroke is 30 μm, the printing speed is 30 mm / s, and the screen printing thickness is 42 μm. After the first time of screen printing, the printed ceramic is placed in an oven and dried at 130°C for 20 min. Then, the second time of screen printing is performed. The process parameters of the second time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 300 mesh, the wire diameter is 45 μm, the screen distance is 2 mm, the doctor blade angle is 75°, the down pressure stroke is 30 μm, the printing speed is 30 mm / s, and the screen printing thickness is 47 μm. After the second time of screen printing, the second printed ceramic is placed in an oven and dried at 130°C for 20 min. After drying, the ceramic material containing a metallized paste layer is obtained. The total thickness of the metallized paste layer is 89 μm, and the surface of the metallized paste layer is free of cracks, grooves, and pits.

[0053] (3) The ceramic material containing the metallized paste layer is placed in a metallization furnace and subjected to metallization sintering at 1500°C for 1 h to obtain a ceramic material containing a metallized layer. The thickness of the metallized layer is about 35 μm.

[0054] Example 4

[0055] (1) The metallized paste is homogenized by a homogenizer under vacuum conditions. The homogenization speed is 1500 r / min, the homogenization time is 10 min, and the vacuum degree is controlled at -120 KPa during homogenization to obtain the homogenized metallized paste. The homogenized metallized paste is placed in an ultrasonic debubbling machine for debubbling. The ultrasonic frequency is 60 KHz, and the debubbling time is 12 min to obtain the activated metallized paste.

[0056] (2) The activated metalized paste is printed on the ceramic sealing surface by two times of screen printing (the width of the ceramic sealing surface is 4 mm). The process parameters of the first time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 165 mesh, the wire diameter is 35 μm, the screen distance is 2 mm, the doctor blade angle is 45°, the downstroke is 30 μm, the printing speed is 80 mm / s, and the screen printing thickness is 30 μm. After the first time of screen printing, the printed ceramic is placed in an oven and dried at 100°C for 40 min. Then, the second time of screen printing is performed, and the process parameters of the second time of screen printing are as follows: the ambient temperature is 22-26°C, the humidity is 30-50%, the screen printing mesh is 165 mesh, the wire diameter is 35 μm, the screen distance is 2 mm, the doctor blade angle is 45°, the downstroke is 30 μm, the printing speed is 80 mm / s, and the screen printing thickness is 32 μm. After the second time of screen printing, the second time of printed ceramic is placed in an oven and dried at 100°C for 40 min. Then, the third time of screen printing is performed according to the process parameters of the second time of screen printing. After printing, the sample is dried at 100°C for 40 min to obtain a ceramic material containing a metalized paste layer. The total thickness of the metalized paste layer is 104 μm, and the metalized paste layer is free of defects such as cracks, grooves, and pits.

[0057] (3) The ceramic material containing the metalized paste layer is placed in a metalizing furnace and subjected to metalizing sintering at 1600°C for 1 h to obtain a ceramic material containing a metalized layer. The thickness of the metalized layer is about 44 μm.

[0058] Performance test:

[0059] 1. Hermeticity detection and tensile test sample detection:

[0060] The metalized layer of the ceramic material containing the metalized layer prepared in Examples 1-4 and Comparative Examples 1-3 is respectively electroplated with nickel, and the thickness of the nickel layer is 6 μm. Then, the sample is placed in a hydrogen furnace and subjected to nickelization at 750°C for 1 h to obtain a ceramic material containing a nickel metal layer. The ceramic material containing the nickel metal layer and a 4J33 alloy gasket are brazed with oxygen-free copper at a brazing temperature of 1090°C for 15 min to obtain a detection sample. The detection sample is subjected to hermeticity detection and tensile test according to industry standards SJ / T3326-2016 and SJ / T11583-2016. The hermeticity is ≤ 1×10 -11 Pa·m 3 ·s -1 , and the tensile strength is ≥ 90 MPa. The test data are shown in Table 1.

[0061] 2. Thermal cycle performance test

[0062] The metallized layer of the ceramic material containing the metallized layer prepared in Examples 1-4 and Comparative Examples 1-3 was respectively electroplated with nickel, and the thickness of the nickel layer was 6 μm, and then was placed in a hydrogen furnace, and nickelized at 750 ℃ for 1 h to obtain a ceramic material containing a nickel metal layer. The ceramic material containing the nickel metal layer was brazed with BNi-9, and the brazing temperature was 1070 ℃, and the holding time was 4 min to obtain a test sample. The test sample was placed in a tube furnace, and was raised from room temperature to 900 ℃ in an air atmosphere, and was held at 900 ℃ for 1 h, and then was cooled to room temperature, and the raising and lowering rates were ≥5 ℃ / min, which was one cycle. The ceramic and metal were observed for separation according to the above procedure, and the ceramic and metal were not separated in 80 cycles, i.e., were qualified. The specific results are shown in Table 1.

[0063] Table 1

[0064]

[0065] As can be seen from the data in Table 1, the ceramic material containing the metallized layer prepared in Example 1 had good air tightness, tensile strength and thermal cycle performance after metal-ceramic sealing. The ceramic material containing the metallized layer prepared in Comparative Examples 1 and 2 had poor air tightness, tensile strength and thermal cycle performance after metal-ceramic sealing. This shows that the thickness of each screen printing and the activation process of the metallized paste have a great influence on the performance of the metallized layer.

[0066] The ceramic material containing the metallized layer prepared in Comparative Example 3 had good air tightness after metal-ceramic sealing, but had poor tensile strength and thermal cycle performance. This is mainly due to the too thin thickness of the metallized layer.

[0067] In Examples 2-4, the preparation process parameters were mainly adjusted, and the ceramic material containing the metallized layer prepared after metal-ceramic sealing had a certain degree of fluctuation in air tightness, tensile strength and thermal cycle performance, but had good air tightness, tensile strength and thermal cycle performance.

[0068] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A method of screen printing a metalizing paste, characterized in that, The method comprises the following steps: Step S1: homogenizing and defoaming activation of the metallized paste in sequence to obtain an activated metallized paste; Step S2: screen printing the activated metallized paste in step S1 on the surface to be sealed of the ceramic material, controlling the thickness of each screen printing to be not more than 50 μm, and obtaining a ceramic material containing a metallized paste layer by multiple screen printing to a set thickness; Step S3: sintering the ceramic material containing the metallized paste layer in step S2 to obtain a ceramic material containing a metallized layer; In step S1, the homogenization is carried out under vacuum condition, the vacuum degree is -120~-90 KPa, the rotation speed of the homogenization is 1200~1600 r / min, and the homogenization time is 10~15 min; the defoaming is carried out by ultrasonic defoaming; In step S2, the set thickness is 55~110 μm.

2. The method for screen printing a metallized paste according to claim 1, wherein the frequency of the ultrasonic defoaming is 40~80 KHz, and the ultrasonic defoaming time is 10~15 min.

3. The method of screen-printing a metalizing paste according to claim 1, characterized in that, In step S2, the process parameters of the screen printing include: screen mesh number is 80~350 meshes, wire diameter is 20~45 μm, screen distance is 2~4 mm, doctor blade angle is 45~85°, downstroke is 28~35 μm, and printing speed is 30~100 mm / s.

4. The method of screen-printing a metalizing paste according to claim 1, characterized in that, In step S2, the thickness of each screen printing is controlled to be 25~50 μm.

5. The method of screen-printing a metalizing paste according to claim 1, wherein, In step S2, drying is carried out after each screen printing; the drying temperature is 100~130 ℃.

6. The method of screen-printing a metalizing paste according to claim 1, wherein, In step S2, the set thickness is 55~110 μm.

7. The method of screen-printing a metalizing paste according to claim 1, wherein, In step S3, the sintering temperature is 1400~1500 ℃, and the sintering holding time is 0.5~1.5 h.

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