A solder for welding ceramics and metals and a preparation method thereof

Abstract

The present invention relates to a solder for welding ceramics and metals and a preparation method thereof. The solder comprises the following raw materials in mass percentage: Ti 20‑45%, Cu 8‑25% and Ag 20‑55%, and comprises at least one of the following raw materials in mass percentage: Al3‑15%, Zr 20‑45%, Ni 25‑40%. The preparation method of the solder for welding ceramics and metals comprises the following steps: mixing, smelting, blank forming, and rolling. The present invention improves the wettability of the alloy solder and ceramics, and improves the strength of the ceramic-metal bonding and the product life by optimizing the component composition of the solder for welding ceramics and metals; the welding strength is high during use and has excellent resistance to high and low temperature impacts, the preparation method is simple in process, easy to control in operation, and is conducive to industrial production, and the obtained solder has good welding effect when used for welding ceramics and metals.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor ceramics, and in particular to a solder for welding ceramics and metals and a preparation method thereof. Background Art

[0002] At present, electronic integration and packaging technology and semiconductor technology are developing towards high integration, multifunctionality and high reliability, which puts forward higher requirements on the reliability of electronic components. Ceramics, especially electronic ceramics, belong to the category of advanced ceramics. They are functional ceramics used in the field of electronic information technology. They are the basic materials for building various electronic ceramic components and occupy an important position in the national economy and national defense construction. Generally, they have the advantages of high melting point, good corrosion resistance and high hardness. Some electronic ceramics have more significant advantages in some aspects, such as high thermal conductivity, large volume resistance, small high-frequency loss, small thermal expansion coefficient and high mechanical strength. They are widely used in the field of electronic packaging and semiconductors. In recent years, due to the miniaturization and high power density of power semiconductor components, the current flow of each component has increased, the heat generation has increased, and the temperature of some special components that need to be heated has also increased, which puts forward higher requirements on the interface between ceramics and metals. Not only does the welding at the interface need to withstand higher temperatures, but it also needs to have better thermal conductivity.

[0003] The commonly used ceramic and metal connection technologies now mainly include mechanical connection, organic adhesive bonding, and low-temperature welding. Among them, mechanical connection is a more traditional connection method, which is mainly through structural design, constructing a snap-on mechanism or using bolts for connection. This method has a large thermal resistance in heat conduction because the ceramic and metal interface is not tightly fitted, but there is an air interlayer, and this method cannot be applied to precision structural components. The use of organic adhesive bonding is a new type of ceramic and metal connection method, which is widely used in the production of electronic components. Its obvious advantage over mechanical connection is that the air interlayer disappears and is replaced by a thermally conductive adhesive, which improves the thermal conductivity to a certain extent, but this type of bonding cannot be applied to working environments above 200°C. Low-temperature welding, as a mature welding process, is also widely used in the preparation of electronic components. Common materials include low-temperature welding materials composed of three or more materials such as Sb, Cu, Sn, Co, Fe, and Bi. This type of solder can be used in the use environment of 200-300°C. If the working temperature of the component is further increased, low-temperature welding cannot meet the requirements. If the components are bonded with organic adhesives or soldered at low temperatures for a long time and are close to the critical temperature or exceed the applicable temperature, the ceramic-metal interface will crack or debond, causing damage to the equipment or components. On the other hand, due to the large difference in thermal expansion coefficients between ceramics and metals, connection failures often occur in the above connections due to poor interface wettability and mismatch between solder and the connected materials. For higher reliability and higher temperature scenarios, solders with matching thermal expansion coefficients, good ductility, high melting points, and good wettability with ceramics and metals are usually required. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies of the prior art, one of the objects of the present invention is to provide a solder for welding ceramics to metals, which has the characteristics of high interface wettability and high melting point. When used, the welding strength between ceramics and metals is high and has excellent resistance to high and low temperature impact.

[0005] Another object of the present invention is to provide a method for preparing solder for welding ceramics to metals. The preparation method has a simple process, easy operation and control, and is conducive to industrial production. When the prepared solder is used for welding ceramics to metals, it has excellent welding strength and good welding effect.

[0006] The object of the present invention is achieved through the following technical solution: a solder for welding ceramics to metals, comprising the following raw materials in mass percentage: Ti 20-45%, Cu 8-25% and Ag 20-55%, and at least one of the following raw materials in mass percentage: Al 3-15%, Zr 20-45%, Ni 25-40%.

[0007] The present invention creatively compounds raw materials such as Ti, Cu, and Ag and carefully designs their dosage ratios to produce solder for welding ceramics and metals. In the process of welding ceramics and metal structural parts, the liquidus line of the welding solder is lower than the solidus line of the metal structural parts, ensuring a good welding effect between the solder and the metal and the structural integrity and accurate size of the metal structural parts. The Ti introduced into the solder of the present invention is in the transition interval of the periodic table and can chemically bond with oxygen, carbon or silicon on the surface of the ceramic, for example, it can react with oxide ceramics to generate TiO, Cu 2 Ti 4 O solid solution, thereby realizing chemical bonding with the ceramic surface to form an active transition layer, which has good wettability to the metal structure, enabling it to effectively wet and diffuse, and finally achieving a good welding effect. The solder has the characteristics of low surface tension, high interface wettability, high melting point and high reliability, high welding strength and excellent resistance to high and low temperature impact.

[0008] Further, the solder for welding ceramics to metals comprises the following raw materials in mass percentage: Ti 25-40%, Cu 10-22%, Ag 25-50%, Al 5-12%. Further, the solder for welding ceramics to metals comprises the following raw materials in mass percentage: Ti 25-38%, Cu 10-23%, Ag 40-48%, Al 7-12%.

[0009] Further, the solder for welding ceramics to metals comprises the following raw materials in mass percentage: Ti 20-40%, Cu 10-22%, Ag 25-50%, Zr 20-45%. Further, the solder for welding ceramics to metals comprises the following raw materials in mass percentage: Ti 25-30%, Cu 10-15%, Ag 25-40%, Zr 25-40%.

[0010] Further, the solder for welding ceramics to metals comprises the following raw materials in mass percentage: Ti 20-40%, Cu 10-22%, Ag 25-50%, Ni 20-45%. Further, the solder for welding ceramics to metals comprises the following raw materials in mass percentage: Ti 20-30%, Cu 10-20%, Ag 25-45%, Ni 20-30%.

[0011] Another object of the present invention is achieved by the following technical solution: A method for preparing the above-mentioned solder for welding ceramics to metals, comprising the following steps:

[0012] (1) Mixing: taking ceramic and metal raw material powders for metal welding solder, mixing them according to a certain proportion to obtain a mixed metal powder;

[0013] (2) Smelting: heating the mixed metal powder obtained in step (1) to 900-1100° C. and smelting it into metal slurry;

[0014] (3) Billet forming: taking out the metal slurry melted in step (2) and pouring it into a water-cooled copper mold, and after cooling, forming an alloy billet;

[0015] (4) Rolling: The alloy blank is heated to 600-800°C and rolled for the first time to obtain an alloy strip; then the oxide layer on the surface of the alloy strip is removed by pickling; the alloy strip with the oxide layer removed is rolled for the second time to obtain a solder strip for welding ceramics to metals.

[0016] In the further step (1), the metal raw material powder for solder for welding ceramics and metals is added into a ball mill according to a proportion, and processed at a speed of 30-50 r / min for 3-8 hours to obtain a mixed metal powder.

[0017] Furthermore, in step (1), the particle size of the metal raw material powder is 20-100 μm.

[0018] Furthermore, in step (2), the mixed metal powder is loaded into a graphite crucible, and placed in a medium frequency induction furnace and heated to 900-1100° C. to melt the mixed metal powder into a metal slurry.

[0019] Furthermore, in the step (2), the medium frequency induction furnace is heated to gradually increase the temperature to 900-1100° C. at a rate of 5-7° C. / min, and the temperature is kept at 900-1100° C. for 0.5-2 h.

[0020] Furthermore, in the step (3), the metal slurry is taken out from the medium frequency induction furnace and poured into a water-cooled copper mold, and after cooling for 15-30 minutes, an alloy blank is formed.

[0021] Furthermore, in the step (4), the alloy blank is heated to 600-800°C and placed in a rolling mill for a first rolling to obtain an alloy strip with a thickness of 2-6 mm; then the oxide layer on the surface of the alloy strip is removed by pickling; the alloy strip with the oxide layer removed is then placed in a rolling mill and rolled for a second time at a temperature of 20-35°C to obtain a solder strip with a thickness of 20-300 μm for welding ceramics to metals.

[0022] Furthermore, in step (4), HF-HNO 3 The alloy strip is cleaned with mixed acid at a temperature of 35-55°C for 10-20 min. 3 In the mixed acid, the concentration of HF is 3-8wt%, HNO 3 The concentration is 10-35wt%.

[0023] Furthermore, in step (4), the HF-HNO 3 In the mixed acid, the concentration of HF is 5-8wt%, HNO 3 The concentration is 15-30wt%.

[0024] In the present invention, welding is used to weld ceramics and metals. The ceramics are preferably but not limited to at least one of aluminum oxide, zirconium oxide, aluminum nitride or silicon nitride. The metal is a metal structural part. The metal structural part is preferably but not limited to copper, nickel, stainless steel or Kovar alloy. The stainless steel can be 310 stainless steel or other stainless steel. The purity of Al, Ti, Ni, Cu, Zr and Ag used in the present invention is 99%-99.99%.

[0025] The beneficial effects of the present invention are as follows: the present invention optimizes the composition of the solder for welding ceramics to metals, thereby improving the wettability of the alloy solder to ceramics, and improving the strength of the bonding between ceramics and metals and the product life, effectively solving the problem that the prior art is difficult to achieve direct welding of ceramics to metal structural parts, and has high requirements for the use environment, poor uniformity, poor quality consistency, and high welding difficulty; the solder has the characteristics of high interface wettability and high melting point, and when used, the welding strength of the ceramics and the metal is high and the weld has excellent resistance to high and low temperature impact, the preparation method is simple in process, easy to control in operation, and is conducive to industrial production, and the obtained solder has good welding effect when used for welding ceramics to metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the operation of using solder for welding metal and ceramic in the present invention.

[0027] Figure 2 The microstructure of the solder No. 6 of Example 2 after being used for welding Kovar metal and aluminum nitride ceramics

[0028] The reference numerals in the drawings are: 100, experimental sample; 110, ceramic sheet; 120, solder; 130, welded metal part; 210, isolation gasket; 220, counterweight. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0030] In a typical embodiment of the present invention, a solder for welding ceramics to metals includes the following raw materials in percentage by mass: Ti 20-40%, Cu 10-22%, Ag 20-50%, Al 5-12%.

[0031] In another embodiment of the present invention, a solder for welding ceramics to metals includes the following raw materials in percentage by mass: Ti 20-40%, Cu 10-22%, Ag 20-50%, and Zr 25-40%.

[0032] In another embodiment of the present invention, a solder for welding ceramics to metals includes the following raw materials in percentage by mass: Ti 20-40%, Cu 10-22%, Ag 20-50%, Ni 25-40%.

[0033] Furthermore, a method for preparing the above-mentioned solder for welding ceramics to metals comprises the following steps:

[0034] (1) Mixing: Take the metal raw material powder for solder for ceramic and metal welding, add it into a ball mill according to the proportion, and process it at a speed of 30-50 r / min for 3-8 hours to obtain a mixed metal powder; the particle size of the metal raw material powder is 20-100 μm;

[0035] (2) Melting: The mixture obtained in step (1) is placed in a graphite crucible and heated to 900-1100° C. in a medium frequency induction furnace to melt the mixed metal powder into a metal slurry.

[0036] (3) Billet forming: The metal slurry melted in step (2) is taken out from the medium frequency induction furnace and poured into a water-cooled copper mold, and after cooling for 15-30 minutes, an alloy billet is formed;

[0037] (4) Rolling: The alloy blank is heated to 600-800°C and placed in a rolling mill for the first rolling to obtain an alloy strip with a thickness of 2-6 mm; then the oxide layer on the surface of the alloy strip is removed by pickling; the alloy strip with the oxide layer removed is then placed in a rolling mill and rolled for a second time at a temperature of 20-35°C to obtain a solder strip with a thickness of 20-300 μm for welding ceramics to metals.

[0038] Furthermore, in the step (2), the medium frequency induction furnace is heated to gradually increase the temperature to 900-1100° C. at a rate of 5-7° C. / min, and the temperature is kept at 900-1100° C. for 0.5-2 h.

[0039] Furthermore, in step (4), HF-HNO 3 The alloy strip is cleaned with mixed acid at a temperature of 35-55°C for 10-20 min. 3 In the mixed acid, the concentration of HF is 3-8wt%, HNO 3 The concentration is 10-35wt%.

[0040] Example 1

[0041] A solder for welding ceramics and metals comprises the following raw materials in percentage by mass: 20-40% Ti, 10-22% Cu, 20-50% Ag and 5-12% Al.

[0042] The method for preparing the above-mentioned solder for welding ceramics to metals comprises the following steps:

[0043] (1) Mixing: Take the metal raw material powder for solder for ceramic and metal welding, add it into a ball mill according to the proportion, and process it at a speed of 50 r / min for 5 hours to obtain a mixed metal powder; the particle size of the metal raw material powder is 40-50 μm;

[0044] (2) Melting: The mixture obtained in step (1) is placed in a graphite crucible and heated to 950° C. in a medium frequency induction furnace to melt the mixed metal powder into a metal slurry.

[0045] (3) Billet forming: The metal slurry melted in step (2) is taken out from the medium frequency induction furnace and poured into a water-cooled copper mold, and after cooling for 20 minutes, an alloy billet is formed;

[0046] (4) Rolling: The alloy blank is heated to 700°C and placed in a rolling mill for the first rolling to obtain an alloy strip with a thickness of 3 mm. The oxide layer on the surface of the alloy strip is then removed by pickling. The alloy strip with the oxide layer removed is then placed in a rolling mill and rolled for a second time at 25°C to obtain a solder strip with a thickness of 100 μm for welding ceramics to metals.

[0047] Furthermore, in step (2), the medium frequency induction furnace is heated to 950° C. at a rate of 7° C. / min, and the temperature is maintained at the highest temperature for 1.5 hours.

[0048] Furthermore, in step (4), HF-HNO 3 The alloy strip was cleaned with mixed acid at a temperature of 45°C for 15 min. 3 In the mixed acid, the concentration of HF is 5wt%, HNO 3 The concentration is 20wt%.

[0049] The solder strip obtained in this embodiment is analyzed by DSC differential scanning calorimeter, and its melting point is measured to be 650-850°C. In the process of welding ceramics and metal structural parts, the inventor designs the liquidus line of the welding solder to be lower than the solidus line of the metal structural parts, so as to ensure the good welding effect between the solder and the metal and the structural integrity and accurate size of the metal structural parts. In addition, the Ti introduced into the solder formula is in the transition interval of the periodic table and can chemically bond with oxygen, carbon or silicon on the surface of the ceramic, for example, it can react with oxide ceramics to generate TiO, Cu 2 Ti 4 O solid solution, thereby achieving chemical bonding with the ceramic surface to form an active transition layer, which has good wettability for metal structural parts, enabling them to effectively wet and diffuse, ultimately achieving a good welding effect.

[0050] In this embodiment, solder is used to conduct welding experiments of alumina ceramic and Kovar metal, and the final welding effect is measured by a thrust meter. The raw material ratios and performance parameters of the solder for welding ceramic and metal are shown in Table 1 below.

[0051] Experiments on welding alumina ceramics and Kovar metal and measuring welding effects. The sample conditions are as follows: Figure 1 As shown, the experimental sample 100 includes a ceramic sheet 110, a solder 120 and a welded metal piece 130. The ceramic sheet 110 is a surface-treated alumina ceramic sheet 110 with a roughness Ra less than 0.2 μm; the solder strip 120 is a solder strip made of different raw material ratios in this embodiment; the welded metal piece 130 is Kovar metal, and the dimensions of the Kovar metal are as follows: a diameter of 20 mm and a thickness of 10 mm; the material of the isolation gasket 210 can be alumina, zirconium oxide or aluminum nitride ceramic; the isolation gasket 210 in this embodiment is an alumina ceramic gasket; the material of the counterweight 220 is tungsten, molybdenum or stainless steel, with a weight of 300-500 g, and the counterweight 220 in this embodiment is tungsten, with a weight of 400 g.

[0052] The experimental method includes the following steps: (S1) placing an alumina ceramic sheet 110, and then placing a solder 120 having a diameter consistent with that of a metal part 130 to be welded on the upper end surface of the alumina ceramic sheet 110; then stacking the metal part 130 to be welded on the solder 120 so that the two are aligned and not offset; (S2) placing an isolation gasket 210 on the upper end surface of the metal part 130 to be welded, the size of the isolation gasket 210 being slightly larger than the metal part 130 to be welded, and then placing a counterweight 220 on the upper end surface of the isolation gasket 210 to form a test assembly; (S3) transferring the test assembly to a brazing furnace, setting a welding process curve according to the melting temperature of the solder, and carrying out the welding process in an argon gas protective atmosphere. After welding is completed, a high and low temperature impact aging test is carried out, and 100 impact tests are carried out in a high and low temperature test box ranging from -20°C to 300°C, and the welding status before and after the experiment is compared.

[0053] Table 1 Solder welding strength of different raw material compositions

[0054] Solder No. Al Cu Ti Ag Melting temperature / ℃ Welding strength / MPa 1 7 15 30 48 761 163 2 7 20 25 48 711 185 3 7 23 30 40 719 158 4 7 15 38 40 824 213 5 12 10 30 48 675 104 6 12 15 30 43 694 137

[0055] It can be seen from Table 1 that when the Ti content is higher, it is more conducive to the formation of active transition layers TiO and Cu on the ceramic surface. 2 Ti 4 O, realizes chemical bond combination with the ceramic surface to form an active transition layer, and it can effectively wet and diffuse on the ceramic and Kovar metal surfaces, and finally achieves a good welding effect. As can be seen from the above table, the solder numbered 4 in Example 1 has the best welding effect, and the corresponding mass percentage content of each raw material of the solder is as follows: Al is 7%, Cu is 15%, Ti is 38%, Ag is 40%, and the welding strength obtained by the thrust gauge test is 213MPa. After passing the high and low temperature impact test, there is no change in the welding position combination. The weld between the ceramic and the metal has excellent welding strength and resistance to high and low temperature impact.

[0056] Example 2

[0057] A solder for welding ceramics and metals comprises the following raw materials in percentage by mass: 20-40% Ti, 10-22% Cu, 20-50% Ag and 25-40% Zr.

[0058] A method for preparing the above-mentioned solder for welding ceramics to metals comprises the following steps:

[0059] (1) Mixing: Take the metal raw material powder for solder for ceramic and metal welding, add it into a ball mill according to the proportion, and process it at a speed of 50 r / min for 8 hours to obtain a mixed metal powder;

[0060] (2) Melting: The mixture obtained in step (1) is placed in a graphite crucible and heated to 1080° C. in a medium frequency induction furnace to melt the mixed metal powder into a metal slurry.

[0061] (3) Billet forming: The metal slurry melted in step (2) is taken out from the medium frequency induction furnace and poured into a water-cooled copper mold, and after cooling for 25 minutes, an alloy billet is formed;

[0062] (4) Rolling: The alloy blank is heated to 750°C and placed in a rolling mill for the first rolling to obtain an alloy strip with a thickness of 5 mm. The oxide layer on the surface of the alloy strip is then removed by pickling. The alloy strip with the oxide layer removed is then placed in a rolling mill and rolled for a second time at 25°C to obtain a solder strip with a thickness of 150 μm for welding ceramics to metals.

[0063] Furthermore, in the step (2), the medium frequency induction furnace is heated to 1080° C. at a rate of 6° C. / min, and the temperature is maintained at 1080° C. for 1.5 hours.

[0064] Furthermore, in step (4), HF-HNO 3 The alloy strip was cleaned with mixed acid at a temperature of 40°C for 15 min. 3 In the mixed acid, the concentration of HF is 5wt%, HNO 3 The concentration is 20wt%.

[0065] The solder strip obtained in this embodiment is analyzed by DSC differential scanning calorimeter, and its melting point is measured to be 750-950°C. In the process of welding ceramics and metal structural parts, the inventor designs the liquidus line of the welding solder to be lower than the solidus line of the metal structural parts, so as to ensure the good welding effect between the solder and the metal and the structural integrity and accurate size of the metal structural parts. In addition, the Ti and Zr introduced into the solder formula are in the transition interval of the periodic table and can chemically bond with oxygen, carbon or silicon on the surface of the ceramic. For example, they can react with the oxides on the surface of the nitride ceramic to generate TiO, Cu 2 Ti 4 O and ZrTiO 4 Solid solution, thereby achieving chemical bond combination with the ceramic surface to form an active transition layer, which has good wettability to metal structural parts, enabling them to effectively wet and diffuse, ultimately achieving a good welding effect.

[0066] In this embodiment, solder is used to conduct welding experiments between aluminum nitride ceramic and Kovar metal, and the final welding effect is measured by a thrust meter. The raw material ratios and performance parameters of the solder for welding ceramic and metal are shown in Table 2 below.

[0067] Table 2 Solder welding strength of different raw material compositions

[0068] Solder No. Cu Ti Zr Ag Melting temperature / ℃ Welding strength / MPa 1 10 25 25 40 781 107 2 10 30 25 35 824 124 3 10 25 30 35 835 143 4 15 25 30 30 847 162 5 15 30 30 25 885 187 6 10 25 40 25 917 226

[0069] It can be seen from Table 2 that when the content of Ti and Zr is high, it is more conducive to the formation of active transition layer TiO and Cu on the surface of aluminum nitride ceramics. 2 Ti 4 O、ZrTiO 4 , achieving chemical bond combination with the ceramic surface to form an active transition layer, and it can effectively wet and diffuse on the surface of aluminum nitride ceramics and Kovar metal, and finally achieve a good welding effect. As can be seen from the above table, the solder numbered 6 in Example 2 has the best welding effect, and the corresponding mass percentage content of each raw material of the solder is as follows: Cu is 10%, Ti is 25%, Zr is 40%, Ag is 25%, and the welding strength obtained by thrust gauge test is 226MPa. After passing the high and low temperature impact test, there is no change in the welding position combination. The weld between ceramic and metal has excellent welding strength and resistance to high and low temperature impact.

[0070] The rest of the content of this embodiment is the same as that of Embodiment 1 and will not be repeated here.

[0071] Example 3

[0072] A solder for welding ceramics and metals comprises the following raw materials in percentage by mass: 20-40% Ti, 10-22% Cu, 20-50% Ag and 25-40% Ni.

[0073] A method for preparing the above-mentioned solder for welding ceramics to metals comprises the following steps:

[0074] (1) Mixing: Take the metal raw material powder for solder for ceramic and metal welding, add it into a ball mill according to the proportion, and process it at a speed of 50 r / min for 8 hours to obtain a mixed metal powder;

[0075] (2) Melting: The mixture obtained in step (1) is placed in a graphite crucible and heated to 900° C. in a medium frequency induction furnace to melt the mixed metal powder into a metal slurry.

[0076] (3) Billet forming: The metal slurry melted in step (2) is taken out from the medium frequency induction furnace and poured into a water-cooled copper mold, and after cooling for 25 minutes, an alloy billet is formed;

[0077] (4) Rolling: The alloy blank is heated to 700°C and placed in a rolling mill for the first rolling to obtain an alloy strip with a thickness of 5 mm. The oxide layer on the surface of the alloy strip is then removed by pickling. The alloy strip with the oxide layer removed is then placed in a rolling mill and rolled for a second time at 25°C to obtain a solder strip with a thickness of 150 μm for welding ceramics to metals.

[0078] Furthermore, in step (2), the medium frequency induction furnace is heated to 900° C. at a rate of 5° C. / min, and the temperature is maintained at 900° C. for 1.5 hours.

[0079] Furthermore, in step (4), HF-HNO 3 The alloy strip was cleaned with mixed acid at a temperature of 45°C for 15 min. 3 In the mixed acid, the concentration of HF is 5wt%, HNO 3 The concentration is 15wt%.

[0080] The solder strip obtained in this embodiment was analyzed using a DSC differential scanning calorimeter, and its melting point was measured to be 550-750°C. The solder was used to conduct a welding experiment of aluminum nitride ceramic and metal copper, and the final welding effect was measured by a thrust meter. The raw material ratios and performance parameters of the solder for welding ceramics to metals are shown in Table 2 below.

[0081] Table 3 Solder welding strength of different raw material compositions

[0082]

[0083] It can be seen from Table 3 that when the content of Ti and Ni is high, it is more conducive to the formation of active transition layer TiO and Cu on the ceramic surface. 2 Ti 4 O, realizes chemical bond combination with the ceramic surface to form an active transition layer, and it can effectively wet and diffuse on the ceramic and metal copper surfaces, and finally achieves a good welding effect. As can be seen from the above table, the solder numbered 5 in Example 3 has the best welding effect, and the corresponding mass percentage content of each raw material of the solder is as follows: Cu is 15%, Ti is 30%, Ni is 30%, Ag is 25%, and the welding strength obtained by the thrust gauge test is 197MPa. After passing the high and low temperature impact test, there is no change in the welding position combination. The weld between the ceramic and the metal has excellent welding strength and resistance to high and low temperature impact.

[0084] The rest of the content of this embodiment is the same as that of Embodiment 1 and will not be repeated here.

[0085] The above specific embodiments are further explanations of the technical solutions and beneficial effects of the present invention, and are not limitations of the implementation methods. For those skilled in the art, any obvious replacements that do not depart from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A solder for welding ceramics to metals, characterized in that: It is composed of the following raw materials in mass percentage: Ti 25-40%, Cu 10-22%, Ag 25-50%, Al 5-12%; or it is composed of the following raw materials in mass percentage: Ti 20-40%, Cu 10-22%, Ag 25-50%, Zr 20-45%; or it is composed of the following raw materials in mass percentage: Ti 25-40%, Cu 10-22%, Ag 20-50%, Ni 25-40%.

2. A method for preparing a solder for welding ceramics to metals as claimed in claim 1, characterized in that: The steps include: (1) Mixing: Take ceramic and metal raw material powders for metal welding solder, mix them according to the proportion, and obtain mixed metal powder; (2) Melting: heating the mixed metal powder obtained in step (1) to 900-1100° C. and melting it into metal slurry; (3) Billet forming: The metal slurry melted in step (2) is taken out and poured into a water-cooled copper mold, and after cooling, an alloy billet is formed; (4) Rolling: The alloy blank is heated to 600-800°C and rolled for the first time to obtain an alloy strip; then the oxide layer on the surface of the alloy strip is removed by pickling; The alloy strip with the oxide layer removed is then rolled for a second time to obtain a solder strip for welding ceramics to metals.

3. The method for preparing a solder for welding ceramics to metals according to claim 2, characterized in that: In the step (2), the mixed metal powder is loaded into a graphite crucible, and placed in a medium frequency induction furnace and heated to 900-1100° C. to melt the mixed metal powder into a metal slurry.

4. The method for preparing a solder for welding ceramics to metals according to claim 2, characterized in that: In the step (2), the medium frequency induction furnace is heated to gradually increase the temperature to 900-1100°C at a rate of 5-7°C / min, and the temperature is kept at 900-1100°C for 0.5-2h.

5. The method for preparing a solder for welding ceramics to metals according to claim 2, characterized in that: In the step (3), the metal slurry is taken out from the medium frequency induction furnace and poured into a water-cooled copper mold, and after cooling for 15-30 minutes, an alloy blank is formed.

6. The method for preparing a solder for welding ceramics to metals according to claim 2, characterized in that: In the step (4), the alloy blank is heated to 600-800°C and placed in a rolling mill for a first rolling to obtain an alloy strip with a thickness of 2-6 mm; then the oxide layer on the surface of the alloy strip is removed by pickling; and the alloy strip with the oxide layer removed is placed in a rolling mill for a second rolling to obtain a solder strip with a thickness of 20-300 μm for welding ceramics to metals.

7. The method for preparing a solder for welding ceramics to metals according to claim 2, characterized in that: In the step (4), the alloy strip is cleaned with HF-HNO3 mixed acid at a cleaning temperature of 35-55°C for a cleaning time of 10-20 min; in the HF-HNO3 mixed acid, the concentration of HF is 3-8wt%, and the concentration of HNO3 is 10-35wt%.

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