Composite filler for brazing between alumina ceramic substrate and copper substrate, method

Abstract

The application discloses a composite brazing filler metal for brazing an alumina ceramic substrate and a copper substrate and a brazing method. The composite brazing filler metal comprises the following components in percentage by mass: 20-60% of a palladium-copper-vanadium-cobalt-manganese alloy powder and 40-80% of elemental powder; wherein the elemental powder comprises one or more than one of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder; in the palladium-copper-vanadium-cobalt-manganese alloy powder, the mass percentage content of palladium is 20.5-21.5%, the mass percentage content of vanadium is 0.5-1%, the mass percentage content of cobalt is 11.5-12.5%, the mass percentage content of manganese is 18.5-19.5%, and the balance is copper. The application increases the elemental powder of palladium-copper-vanadium-cobalt-manganese to enhance the brazing connection of the palladium-copper-vanadium-cobalt-manganese alloy powder brazing filler metal, thereby not only relieving residual stress but also reducing the thermal expansion coefficient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of brazing, more particularly to a composite filler for brazing an alumina ceramic substrate and a copper substrate and a method. BACKGROUND

[0002] With the rapid development of economy and the overall progress of society, China's energy supply and environmental problems are increasingly concerned. But thanks to the demand for new energy vehicles, new energy power generation and other needs, power electronics technology and its application have made great strides, effectively easing the energy crisis and the continuous deterioration of the ecological environment. Electronic power devices represented by IGBT (Insulated Gate Bipolar Transistor) have grown rapidly, and the production capacity cannot meet the demand, gradually becoming one of the core devices of electronic power devices. At present, the threshold of the IGBT device industry is very high, in addition to the design and production of chips, the development and production of IGBT module packaging testing also have very high technical requirements and process requirements.

[0003] Under the background of rapid growth of IGBT in industrial control field, power industry, home appliance industry, new energy vehicles and photovoltaic, high-performance alumina ceramic substrate has been used as the preferred heat dissipation substrate for high-density and high-power electronic packaging due to its low dielectric constant, high thermal conductivity and matching with chips.

[0004] In recent years, ceramic substrates and traditional metal materials are combined to form ceramic substrate-metal composite materials, which not only retain the advantages of ceramic substrates, but also overcome or avoid their disadvantages. For example, to meet the high current requirement of IGBT module, researchers ingeniously connected alumina ceramic substrate with oxygen-free copper plate, thereby forming an alumina-oxygen-free copper composite substrate with good performance. The composite substrate not only realizes the basic circuit topology interconnection structure, but also guarantees the high power density and good heat dissipation performance of the device.

[0005] However, there is a problem of large difference in thermal expansion coefficient between the alumina ceramic substrate and the copper substrate, which often produces a large residual stress during brazing cooling. The presence of residual stress directly leads to a significant reduction in the strength of the brazing structure (joint part), which greatly affects the stability of the device. Therefore, relieving the residual stress in the brazing joint is one of the key prerequisites for preparing an alumina-copper composite substrate with good performance and high reliability. SUMMARY

[0006] The present application aims to overcome the above-mentioned defects in the prior art, and provides a composite filler for brazing an alumina ceramic substrate and a copper substrate and a method, which is used to solve the problem of unstable brazing between the alumina ceramic substrate and the copper substrate.

[0007] To achieve the above-mentioned purpose, the technical solutions of the present application are as follows:

[0008] A composite filler for brazing an alumina ceramic substrate and a copper substrate, characterized in that it comprises the following components by mass percentage:

[0009] 20-60% of palladium-copper-vanadium-cobalt-manganese alloy powder and 40-80% of elemental powder;

[0010] The elemental powder comprises one or more of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder.

[0011] In the palladium-copper-vanadium-cobalt-manganese alloy powder, the mass percentage of palladium is 20.5-21.5%, the mass percentage of vanadium is 0.5-1%, the mass percentage of cobalt is 11.5-12.5%, the mass percentage of manganese is 18.5-19.5%, and the balance is copper.

[0012] A method for brazing an alumina ceramic substrate and a copper substrate, comprising the following processes:

[0013] Providing palladium-copper-vanadium-cobalt-manganese alloy powder, the mass percentage of each element in the palladium-copper-vanadium-cobalt-manganese alloy powder being as described above.

[0014] Providing elemental powder, the elemental powder comprising one or more of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder.

[0015] Mixing the palladium-copper-vanadium-cobalt-manganese alloy powder and the elemental powder in the above-mentioned proportions to obtain a mixed powder;

[0016] Pressing the mixed powder into a filler foil;

[0017] Placing the filler foil at the brazing joint of the alumina ceramic substrate and the copper substrate to obtain a brazed assembly;

[0018] Vacuum brazing the brazed assembly to obtain a brazed assembly.

[0019] Implementing the embodiments of the present application will have the following beneficial effects:

[0020] The embodiments of the present application increase the elemental powder of palladium-copper-vanadium-cobalt-manganese to enhance the brazing connection of the palladium-copper-vanadium-cobalt-manganese alloy powder filler to the alumina ceramic substrate and the copper substrate, utilize the principle of refining the microstructure of the brazing seam with elemental powder, not only relieve the residual stress of the joint during brazing cooling, but also reduce the thermal expansion coefficient of the joint, effectively improve the mechanical stability of the joint. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0022] The present application discloses a kind of composite filler for brazing alumina ceramic substrate and copper substrate, comprising the following mass percentage components:

[0023] 20%~60% palladium copper vanadium cobalt manganese alloy powder and 40%~80% elemental powder;Wherein, elemental powder includes one or more than two of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder;In palladium copper vanadium cobalt manganese alloy powder, the mass percentage content of palladium is 20.5~21.5%, the mass percentage content of vanadium is 0.5~1%, the mass percentage content of cobalt is 11.5~12.5%, the mass percentage content of manganese is 18.5~19.5%, and the balance is copper.

[0024] In the above technical solution, by increasing the elemental powder of palladium copper vanadium cobalt manganese, the brazing connection of palladium copper vanadium cobalt manganese alloy powder filler to alumina ceramic substrate and copper substrate is enhanced, using the principle of refining the microstructure of the filler seam with elemental powder, not only relieving the residual stress of the joint during brazing cooling, but also reducing the thermal expansion coefficient of the joint, effectively improving the mechanical stability of the joint. By increasing the same elemental powder as the palladium copper vanadium cobalt manganese alloy element, the alloy lattice defects are minimized to enhance the mechanical properties of the joint.

[0025] In a more preferred embodiment, the average particle size of the elemental powder is smaller than the average particle size of the palladium copper vanadium cobalt manganese alloy powder, which facilitates the elemental powder to enter the microstructure of the filler seam.

[0026] Specifically, in a specific embodiment, the average particle size of the palladium copper vanadium cobalt manganese alloy powder is 100 mesh~300 mesh;The average particle size of palladium powder is 50 μm~100 μm;The average particle size of copper powder is 20 μm~60 μm;The average particle size of vanadium powder is 10 μm~40 μm;The average particle size of cobalt powder is 40 μm~100 μm;The average particle size of manganese powder is 40 μm~100 μm.

[0027] More preferably, in a specific embodiment, the elemental powder comprises the following components by mass fraction:

[0028] 16 parts~24 parts of palladium powder, 40 parts~56 parts of copper powder, 0.8 parts~1.2 parts of vanadium powder, 10 parts~14 parts of cobalt powder and 15 parts~23 parts of manganese powder.

[0029] In the technical solution, the multi-element single-element powder and the alloy powder can be arranged more densely in the microstructure, so as to reduce the expansion coefficient and reduce the residual stress.

[0030] In the above embodiments, the purity of the palladium-copper-vanadium-cobalt-manganese alloy powder and the single-element powder is greater than 99.5%.

[0031] The application further discloses a method for brazing an alumina ceramic substrate and a copper substrate, which comprises the following steps:

[0032] 1. A palladium-copper-vanadium-cobalt-manganese alloy powder is provided, and the mass percentage content of each element in the palladium-copper-vanadium-cobalt-manganese alloy powder is as described above.

[0033] In an embodiment, the preparation method of the palladium-copper-vanadium-cobalt-manganese alloy powder comprises the following steps:

[0034] 1.1. According to the mass percentage content of each element in the palladium-copper-vanadium-cobalt-manganese alloy powder, a mixture including palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is configured.

[0035] 1.2. The mixture is melted to obtain an alloy melt.

[0036] In this step, the high-melting-point single-element can be melted first, and then the low-melting-point single-element is added after complete melting, until all components are melted to obtain the alloy melt.

[0037] In an embodiment, the temperature of melting can be set to 1600-1900 DEG C, and overheat melting is adopted, which is beneficial to obtain fine powder.

[0038] 1.3. The alloy melt is atomized and granulated to obtain alloy droplets.

[0039] In an embodiment, the alloy melt is placed in a leaky bag, and the alloy melt is atomized and granulated by using a high-pressure atomization medium.

[0040] Preferably, the pressure of atomization and granulation is 5-10 MPa, so as to scatter and crush the droplets into fine particles.

[0041] Preferably, the leaky bag is preheated to above 850 DEG C, so as to prevent the temperature of the alloy melt from being too low in the atomization process and thus affecting the atomization effect.

[0042] 1.4. The alloy droplets are cooled in a cooling liquid to obtain alloy particles.

[0043] The alloy droplets falling from the leaky bag are scattered and crushed into fine alloy droplets by the high-pressure atomization medium, and then fall into the cooling liquid and are rapidly cooled and solidified to obtain alloy particles.

[0044] 1.5, dry, grind, sieve the alloy particles to obtain the palladium copper vanadium cobalt manganese alloy powder.

[0045] The palladium copper vanadium cobalt manganese alloy powder is preferably stored in a vacuum box to prevent oxidation.

[0046] 2, provide elemental powder, the elemental powder includes one or more than two of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder.

[0047] 3, the palladium copper vanadium cobalt manganese alloy powder and the elemental powder are mixed according to the aforementioned proportions to obtain a mixed powder.

[0048] Specifically, the palladium copper vanadium cobalt manganese alloy powder and the elemental powder can be ground and mixed, and the obtained mixed powder

[0049] 4, the mixed powder is pressed into a solder foil.

[0050] In this step, the mixed powder is placed in a mold, the mold is first placed in an ultrasonic vibrator for oscillation for 5-10 min to make the powder evenly distributed in the mold cavity, then a manual powder tablet press is used to load pressure for pressing, the pressure holding time is 2 min, then the pressure is released and demolded to obtain a solder foil with a corresponding thickness.

[0051] Preferably, the inner wall of the mold and the loading surface of the upper and lower mold punches are smeared with zinc stearate alcohol solution, which can ensure the quality of the pressed blank and avoid difficulty in demolding later.

[0052] In a specific embodiment, the thickness of the solder foil is 0.2-1.0 mm.

[0053] 5, place the solder foil at the brazing connection between the alumina ceramic substrate and the copper substrate to obtain a brazed assembly.

[0054] In a specific embodiment, the solder foil is placed on the alumina ceramic substrate, then the copper substrate is placed on the solder foil, and then a tungsten block with a pressure of 1-2 MPa is placed above the copper substrate to ensure close contact between the assembly layers during brazing. Then send it into a vacuum tube furnace and start heating according to the set program.

[0055] 6, vacuum brazing of the brazed assembly to obtain a brazed assembly.

[0056] In a specific embodiment, the vacuum brazing includes the following processes:

[0057] Place the brazed assembly in a vacuum environment (vacuum degree is 4x10 -3The brazing method comprises the following processes:

[0058] In the above scheme, the first temperature rising is to melt the brazing filler metal and to make the brazing filler metal fully wet the two substrates to be bonded, the second temperature rising is to make the brazing filler metal and the two substrates to be bonded diffuse with each other, and the vacuum brazing is to prevent the brazing filler metal from being oxidized.

[0059] The following are specific examples.

[0060] Example 1

[0061] The composite brazing filler metal comprises the following components by mass percentage:

[0062] 40% of palladium-copper-vanadium-cobalt-manganese alloy powder and 60% of elemental powder; wherein the elemental powder comprises palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder, and the ratio of the palladium powder, the copper powder, the vanadium powder, the cobalt powder and the manganese powder is 20:48:1:12:19, and the particle size of the palladium powder, the copper powder, the vanadium powder, the cobalt powder and the manganese powder is 80 μm, 40 μm, 30 μm, 80 μm and 80 μm respectively.

[0063] The palladium-copper-vanadium-cobalt-manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese and the balance of copper.

[0064] The brazing method comprises the following processes:

[0065] 1) Palladium-copper-vanadium-cobalt-manganese alloy powder is prepared. The palladium-copper-vanadium-cobalt-manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800°C, appropriate stirring is performed during the smelting process, the spout is preheated to above 850°C, the alloy melt is placed in the spout, 8 MPa high-pressure argon gas is applied to the alloy melt for atomization, the alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and are rapidly cooled and solidified, and finally the alloy powder is collected by the powder collecting barrel, the alloy powder is placed in an electric vacuum drying oven (temperature is 80°C) for drying, and the dried alloy powder is obtained; then the dried alloy powder is ground and sieved to prevent powder agglomeration; finally, the ground and sieved alloy brazing filler metal powder is transferred into a vacuum box for storage to prevent oxidation.

[0066] 2) The alloy powder and each elemental powder are placed in a mortar and ground for 20 min to obtain a mixed powder.

[0067] 3) Before pressing, the inner wall of the mold and the upper and lower mold punch loading surface need to be coated with zinc stearate alcohol solution, then the mixed powder is put into the mold, placed in the ultrasonic vibration instrument for 10 min, so that the powder is evenly distributed in the mold cavity, the inner cavity diameter of the mold is 10 mm, the manual powder tablet press is used to load pressure, the pressure maintaining time is 2 min, then the pressure is released and the mold is demolded, the thickness of the brazing foil is 0.6 mm.

[0068] 4) Select the size specification of 10mm x 10mm x 2mm of alumina ceramic substrate and oxygen-free copper substrate, polish the alumina ceramic surface to be welded with 800# and 1000# metallographic sandpaper in turn, after polishing, immerse in acetone solution for ultrasonic cleaning, finally rinse with alcohol and blow dry, get the alumina ceramic substrate to be welded. The brazing foil is placed on the alumina ceramic, and the oxygen-free copper substrate is placed on the brazing foil, forming the brazing assembly of alumina ceramic substrate-brazing foil-oxygen-free copper substrate. Place a tungsten block with a pressure of 2MPa on the brazing assembly to ensure close contact between the assembly layers during brazing. Then send it into the vacuum tube furnace.

[0069] 5) The vacuum tube furnace is evacuated to 4x10 -3 Pa below, first heated to 300℃ at a rate of 10℃ / min and kept for 15min; then heated to 1260℃ at a rate of 10℃ / min and kept for 25min; finally, the temperature is decreased to 300℃ at a rate of 10℃ / min, and the product is taken out after natural cooling to room temperature, to get the bonded alumina ceramic copper-clad product.

[0070] Example 2

[0071] The difference between this embodiment and example 1 is that the mass of multi-element Pd, Cu, V, Co, Mn elemental powder is 40.0% of the total mass of the composite filler powder. The other steps are the same as example 1.

[0072] The composite filler comprises the following components by mass percentage:

[0073] 60% of palladium copper vanadium cobalt manganese alloy powder and 40% of elemental powder; wherein the elemental powder comprises palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder, and the ratio of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 20:48:1:12:19, and the particle size of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 80μm, 40μm, 30μm, 80μm and 80μm respectively.

[0074] The palladium copper vanadium cobalt manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese, and the balance of copper.

[0075] The brazing method comprises the following processes:

[0076] 1) Preparation of palladium copper vanadium cobalt manganese alloy powder. The palladium copper vanadium cobalt manganese is placed in a graphite crucible and heated in a smelting furnace, the furnace temperature is set to 1800℃, appropriate stirring during smelting, the ladle is preheated to above 850℃, the alloy melt is placed in the ladle, and the alloy melt is atomized by applying 8MPa high pressure argon gas, the alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and is rapidly cooled and solidified, and finally the alloy powder is collected in the powder collecting barrel, the alloy powder is placed in an electric vacuum drying oven (temperature is 80℃) to obtain dried alloy powder; then the dried alloy powder is ground and sieved to prevent powder agglomeration; finally, the ground and sieved alloy filler powder is transferred into a vacuum box for storage to prevent oxidation.

[0077] 2) The alloy powder and each single element powder are ground in a mortar for 20min to obtain a mixed powder.

[0078] 3) Before pressing, zinc stearate alcohol solution is applied to the inner wall of the mold and the upper and lower mold punch loading surface, then the mixed powder is placed in the mold and placed in an ultrasonic vibration instrument for 10min to make the powder evenly distributed in the mold cavity, the inner cavity diameter of the mold used is 10mm, a manual powder tablet press is used to load pressure, the pressure maintaining time is 2min, then the pressure is released and the mold is demolded to obtain a brazing foil with a thickness of 0.6mm.

[0079] 4) Alumina ceramic substrates and oxygen-free copper substrates with size specifications of 10mm x 10mm x 2mm are selected, the brazing surface of the alumina ceramic is polished with 800# and 1000# metallographic sandpaper in turn, then immersed in acetone solution for ultrasonic cleaning, finally washed with alcohol and blown dry to obtain the brazing surface of the alumina ceramic substrate. The brazing foil is placed on the alumina ceramic, and the oxygen-free copper substrate is placed on the brazing foil to form an alumina ceramic substrate-brazing foil-oxygen-free copper substrate brazing assembly. A tungsten block with a pressure of 2MPa is placed on the brazing assembly to ensure close contact between the assembly layers during brazing. Then it is sent into a vacuum tube furnace.

[0080] 5) The vacuum tube furnace is evacuated to below 4x10 -3 pa, first heated to 300℃ at a rate of 10℃ / min and held for 15min; then heated to 1260℃ at a rate of 10℃ / min and held for 25min; finally, the temperature is decreased to 300℃ at a rate of 10℃ / min, and the product is taken out after natural cooling to room temperature to obtain the bonded alumina ceramic copper clad product.

[0081] Example 3

[0082] The embodiment is different from embodiment 1 in that the mass of the multi-element Pd, Cu, V, Co, Mn elemental powder is 80.0wt.% of the total mass of the composite filler metal powder. The other steps are the same as in embodiment 1.

[0083] The composite filler metal comprises the following components by mass percentage:

[0084] 20% of the palladium copper vanadium cobalt manganese alloy powder and 80% of the elemental powder; wherein the elemental powder comprises palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder, and the ratio of the palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 20:48:1:12:19, and the particle size of the palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 80μm, 40μm, 30μm, 80μm and 80μm respectively.

[0085] The palladium copper vanadium cobalt manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese and the balance of copper.

[0086] The brazing method comprises the following processes:

[0087] 1) Palladium copper vanadium cobalt manganese alloy powder is prepared. The palladium copper vanadium cobalt manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800℃, appropriate stirring is performed during the smelting process, the alloy liquid is placed in a tundish which is preheated to above 850℃, high-pressure argon gas of 8MPa is applied to atomize the alloy liquid, the alloy liquid drops into the cooling water at the bottom of the atomization barrel and is rapidly cooled and solidified, and finally the alloy powder is collected in a powder collecting barrel, the alloy powder is placed in an electric vacuum drying oven (temperature is 80℃) for drying, and the dried alloy powder is obtained; then the dried alloy powder is ground and sieved to prevent powder agglomeration; finally, the ground and sieved alloy filler metal powder is transferred into a vacuum box for storage to prevent oxidation.

[0088] 2) The alloy powder and each elemental powder are placed in a mortar and ground for 20min to obtain a mixed powder.

[0089] 3) Before pressing, zinc stearate alcohol solution is applied to the inner wall of the mold and the upper and lower mold punch loading surfaces, then the mixed powder is placed in the mold, placed in an ultrasonic vibrator for 10min to make the powder evenly distributed in the mold cavity, the inner cavity diameter of the mold used is 10mm, a manual powder tablet press is used to load pressure, the pressure maintaining time is 2min, then the pressure is released and the mold is demolded, and a filler metal foil with a thickness of 0.6mm is prepared.

[0090] 4) Selecting the size specification of 10mm x 10mm x 2mm alumina ceramic substrate and oxygen-free copper substrate, the alumina ceramic to be welded surface is polished with 800# and 1000# metallographic sandpaper in turn, after polishing, it is immersed in acetone solution for ultrasonic cleaning, finally it is washed with alcohol and dried, to obtain the alumina ceramic substrate to be welded. The brazing filler metal foil is placed on the alumina ceramic, and then the oxygen-free copper substrate is placed on the brazing filler metal foil, forming the brazing assembly of alumina ceramic substrate-brazing filler metal foil-oxygen-free copper substrate. A tungsten block with a pressure of 2MPa is placed on the brazing assembly to ensure the close contact between the assembly layers during brazing. Then it is sent into the vacuum tube furnace.

[0091] 5) The vacuum tube furnace is evacuated to 4x10 -3 Pa below, first heated to 300℃ at a rate of 10℃ / min, then heated to 1260℃ at a rate of 10℃ / min for 25min, finally cooled to 300℃ at a rate of 10℃ / min, and taken out after natural cooling to room temperature, to obtain the bonded alumina ceramic copper clad product.

[0092] Example 4

[0093] The difference between this example and example 1 is that in step 5), first heated to 300℃ at a rate of 5℃ / min for 5min, then heated to 1140℃ at a rate of 5℃ / min for 5min, and other proportions and steps are the same as example 1.

[0094] The composite brazing filler metal comprises the following components by mass percentage:

[0095] 40% of palladium copper vanadium cobalt manganese alloy powder and 60% of elemental powder; wherein the elemental powder comprises palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder, and the ratio of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 20:48:1:12:19, and the particle size of palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 80μm, 40μm, 30μm, 80μm and 80μm respectively.

[0096] The palladium copper vanadium cobalt manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese, and the balance of copper.

[0097] The brazing method comprises the following processes:

[0098] 1) Preparation of palladium copper vanadium cobalt manganese alloy powder. The palladium copper vanadium cobalt manganese is placed in a graphite crucible and heated in a smelting furnace, with the furnace temperature set to 1800℃, and appropriate stirring during the smelting process. The pouring ladle is preheated to above 850℃, the alloy melt is placed in the pouring ladle, and high-pressure argon gas of 8MPa is applied to atomize the alloy melt. The alloy liquid drops into the cooling water at the bottom of the atomization barrel and is rapidly cooled and solidified. Finally, the alloy powder is collected in the powder collecting barrel, and the alloy powder is placed in an electric vacuum drying oven (temperature 80℃) to obtain dried alloy powder. The dried alloy powder is then ground and sieved to prevent powder agglomeration. Finally, the ground and sieved alloy filler powder is transferred into a vacuum box for storage to prevent oxidation.

[0099] 2) The alloy powder and each single element powder are ground in a mortar for 20min to obtain a mixed powder.

[0100] 3) Before pressing, zinc stearate alcohol solution is applied to the inner wall of the mold and the upper and lower mold punch loading surface. Then the mixed powder is placed in the mold and placed in an ultrasonic vibration instrument for 10min to make the powder evenly distributed in the mold cavity. The inner cavity diameter of the mold used is 10mm, and the manual powder tablet press is used for loading pressure. The pressure maintaining time is 2min, then the pressure is released and the mold is demolded to obtain a brazing foil with a thickness of 0.6mm.

[0101] 4) Alumina ceramic substrates and oxygen-free copper substrates with size specifications of 10mm x 10mm x 2mm are selected. The welding surface of the alumina ceramic is polished with 800# and 1000# metallographic sandpaper in turn, then immersed in acetone solution for ultrasonic cleaning, and finally washed with alcohol and blown dry to obtain the alumina ceramic substrate to be welded. The brazing foil is placed on the alumina ceramic, and the oxygen-free copper substrate is placed on the brazing foil to form an alumina ceramic substrate-brazing foil-oxygen-free copper substrate brazing assembly. A tungsten block with a pressure of 2MPa is placed on the brazing assembly to ensure close contact between the assembly layers during brazing. Then it is sent into a vacuum tube furnace.

[0102] 5) The vacuum tube furnace is evacuated to below 4x10 -3 pa, first heated to 300℃ at a rate of 5℃ / min and held for 5min, then heated to 1140℃ at a rate of 5℃ / min and held for 5min, and finally cooled to 300℃ at a rate of 10℃ / min, and naturally cooled to room temperature. The bonded alumina ceramic copper-clad product is obtained.

[0103] Example 5

[0104] The difference between this example and Example 1 is that the palladium copper vanadium cobalt manganese alloy powder contains 21.5% palladium, 1% vanadium, 12.5% cobalt, 19.5% manganese, and the balance copper.

[0105] Composite filler, comprising the following components by mass percentage:

[0106] 40% of palladium copper vanadium cobalt manganese alloy powder and 60% of elemental powder; wherein the elemental powder comprises palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder, and the ratio of the palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 20:48:1:12:19, and the particle size of the palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 80 μm, 40 μm, 30 μm, 80 μm and 80 μm respectively.

[0107] The palladium copper vanadium cobalt manganese alloy powder contains 21.5% of palladium, 1% of vanadium, 12.5% of cobalt, 19.5% of manganese, and the balance of copper.

[0108] The brazing method comprises the following processes:

[0109] 1) Palladium copper vanadium cobalt manganese alloy powder is prepared. The palladium copper vanadium cobalt manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800℃, appropriate stirring is performed during the smelting process, the spout is preheated to above 850℃, the alloy melt is placed in the spout, 8 MPa high-pressure argon gas is applied to atomize the alloy melt, the alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and is rapidly cooled and solidified, and finally the alloy powder is collected by the powder collecting barrel, the alloy powder is placed in an electric vacuum drying oven (temperature is 80℃) for drying, and the dried alloy powder is obtained; then the dried alloy powder is ground and sieved to prevent powder agglomeration; finally, the ground and sieved alloy filler powder is transferred into a vacuum box for storage to prevent oxidation.

[0110] 2) The alloy powder and each elemental powder are placed in a mortar and ground for 20 min to obtain a mixed powder.

[0111] 3) Before pressing, zinc stearate alcohol solution is applied to the inner wall of the mold and the upper and lower mold punch loading surfaces, then the mixed powder is placed in the mold, placed in an ultrasonic vibrator for 10 min to make the powder evenly distributed in the mold cavity, the inner cavity diameter of the mold used is 10 mm, a manual powder tablet press is used to load pressure, the pressure maintaining time is 2 min, then the pressure is released and the mold is demolded, and a brazing foil with a thickness of 0.6 mm is prepared.

[0112] 4) Selecting the size specification of 10 mm x 10 mm x 2 mm alumina ceramic substrate and oxygen-free copper substrate, the alumina ceramic to be welded surface is polished with 800# and 1000# metallographic sandpaper in turn, after polishing, it is immersed in acetone solution for ultrasonic cleaning, finally it is rinsed with alcohol and dried, obtaining the alumina ceramic substrate to be welded. The brazing filler metal foil is placed on the alumina ceramic, and then the oxygen-free copper substrate is placed on the brazing filler metal foil, forming the brazing assembly of alumina ceramic substrate-brazing filler metal foil-oxygen-free copper substrate. A tungsten block with a pressure of 2 MPa is placed on the brazing assembly to ensure the close contact between the assembly layers during brazing. Then it is sent into the vacuum tube furnace.

[0113] 5) The vacuum tube furnace is evacuated to 4 x 10 -3 Pa below, first heated to 300℃ at a rate of 10℃ / min for 15 min, then heated to 1260℃ at a rate of 10℃ / min for 25 min, finally cooled to 300℃ at a rate of 10℃ / min, and taken out after natural cooling to room temperature, obtaining the bonded alumina ceramic copper-clad product.

[0114] Example 6

[0115] The difference between this example and Example 1 is that the elemental powder only includes copper powder.

[0116] The composite brazing filler metal includes the following components by mass percentage:

[0117] 40% of palladium-copper-vanadium-cobalt-manganese alloy powder and 60% of elemental powder; wherein the elemental powder is only copper powder, and the particle size of the copper powder is 40μm.

[0118] The palladium-copper-vanadium-cobalt-manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese, and the balance of copper.

[0119] The brazing method includes the following processes:

[0120] 1) Preparation of palladium-copper-vanadium-cobalt-manganese alloy powder. The palladium-copper-vanadium-cobalt-manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800℃, and appropriate stirring is performed during the smelting process. The alloy melt is placed in a tundish preheated to above 850℃, and high-pressure argon gas of 8 MPa is applied to atomize the alloy melt. The alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and are rapidly cooled and solidified. Finally, the alloy powder is collected in a powder collection barrel, and the alloy powder is dried in an electric vacuum drying oven (temperature 80℃) to obtain dried alloy powder. Then the dried alloy powder is ground and sieved to prevent powder agglomeration. Finally, the ground and sieved alloy brazing filler metal powder is transferred into a vacuum box for storage to prevent oxidation.

[0121] 2) Put the alloy powder and copper powder in a mortar and grind for 20 min to obtain a mixed powder.

[0122] 3) Before pressing, the inner wall of the mold and the loading surface of the upper and lower dies are coated with a zinc stearate alcohol solution, then the mixed powder is placed in the mold and oscillated in an ultrasonic vibrator for 10 min to make the powder evenly distributed in the mold cavity. The mold cavity diameter is 10 mm, and a manual powder tablet press is used to load the pressure, and the pressure maintaining time is 2 min. Then, the pressure is released and the mold is demolded to obtain a brazing foil with a thickness of 0.6 mm.

[0123] 4) Select an alumina ceramic substrate and an oxygen-free copper substrate with a size of 10 mm x 10 mm x 2 mm. The welding surface of the alumina ceramic is polished with 800# and 1000# metallographic sandpaper, respectively, and then immersed in an acetone solution for ultrasonic cleaning. Finally, it is washed with alcohol and dried to obtain the alumina ceramic substrate to be welded. The brazing foil is placed on the alumina ceramic, and the oxygen-free copper substrate is placed on the brazing foil to form an alumina ceramic substrate-brazing foil-oxygen-free copper substrate brazing assembly. A tungsten block with a pressure of 2 MPa is placed on the brazing assembly to ensure close contact between the assembly layers during brazing. Then it is sent to a vacuum tube furnace.

[0124] 5) The vacuum tube furnace is evacuated to below 4 x 10 -3 pa, first heated to 300℃ at a rate of 10℃ / min and held for 15 min, then heated to 1260℃ at a rate of 10℃ / min and held for 25 min, and finally cooled to 300℃ at a rate of 10℃ / min, and naturally cooled to room temperature. The alumina ceramic copper-clad product is obtained.

[0125] Example 7

[0126] The difference between this example and Example 1 is that the elemental powder only includes palladium powder.

[0127] The composite brazing filler metal includes the following components by mass percentage:

[0128] 40% of palladium-copper-vanadium-cobalt-manganese alloy powder and 60% of elemental powder; wherein the elemental powder is only palladium powder, and the particle size of the palladium powder is 80 μm.

[0129] The palladium-copper-vanadium-cobalt-manganese alloy powder contains 20.5% palladium, 0.5% vanadium, 11.5% cobalt, 18.5% manganese, and the balance is palladium.

[0130] The brazing method includes the following processes:

[0131] 1) Preparation of palladium copper vanadium cobalt manganese alloy powder. The palladium copper vanadium cobalt manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800℃, appropriate stirring is applied during the smelting process, the pouring ladle is preheated to above 850℃, the alloy melt is placed in the pouring ladle, high pressure argon gas of 8MPa is applied to atomize the alloy melt, the alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and are rapidly cooled and solidified, finally the alloy powder is collected in the powder collecting barrel, the alloy powder is placed in an electric vacuum drying oven (temperature is 80℃) for drying, and the dried alloy powder is obtained; then the dried alloy powder is ground and sieved to prevent powder agglomeration; finally, the ground and sieved alloy filler powder is transferred into a vacuum box for storage to prevent oxidation.

[0132] 2) The alloy powder and palladium powder are ground in a mortar for 20 minutes to obtain a mixed powder.

[0133] 3) Before pressing, zinc stearate alcohol solution is applied to the inner wall of the mold and the upper and lower mold punch loading surface, then the mixed powder is placed in the mold, placed in an ultrasonic vibrator for 10 minutes to make the powder evenly distributed in the mold cavity, the inner cavity diameter of the mold used is 10mm, a manual powder tablet press is used for loading pressure, the pressure maintaining time is 2 minutes, then the pressure is released and the mold is demolded, and a brazing filler metal foil with a thickness of 0.6mm is prepared.

[0134] 4) Select the size specification of the alumina ceramic substrate and oxygen-free copper substrate as 10mmx10mmx2mm, polish the welding surface of the alumina ceramic in turn with 800# and 1000# metallographic sandpaper, after polishing, immerse in acetone solution for ultrasonic cleaning, finally rinse with alcohol and blow dry, and obtain the alumina ceramic substrate to be welded. Place the brazing filler metal foil on the alumina ceramic, then place the oxygen-free copper substrate on the brazing filler metal foil, forming an alumina ceramic substrate-brazing filler metal foil-oxygen-free copper substrate brazing assembly. Place a tungsten block with a pressure of 2MPa on the brazing assembly to ensure close contact between the assembly layers during brazing. Then send it into a vacuum tube furnace.

[0135] 5) The vacuum tube furnace is evacuated to below 4x10 -3 Pa, first heated to 300℃ at a rate of 10℃ / min and kept for 15min, then heated to 1260℃ at a rate of 10℃ / min and kept for 25min, finally cooled to 300℃ at a rate of 10℃ / min, and taken out after natural cooling to room temperature, to obtain the bonded alumina ceramic copper-clad product.

[0136] Example 8

[0137] The difference between this example and example 1 is that the elemental powder only includes vanadium powder.

[0138] The composite filler metal comprises the following components by mass percentage:

[0139] 40% of palladium copper vanadium cobalt manganese alloy powder and 60% of elemental powder; wherein the elemental powder is only vanadium powder, and the particle size of the vanadium powder is 30 μm.

[0140] The palladium copper vanadium cobalt manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese, and the balance of palladium.

[0141] The brazing method comprises the following processes:

[0142] 1) Palladium copper vanadium cobalt manganese alloy powder is prepared. Palladium copper vanadium cobalt manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800℃, appropriate stirring is performed during the smelting process, the spout is preheated to above 850℃, the alloy melt is placed in the spout, high-pressure argon gas of 8 MPa is applied to atomize the alloy melt, the alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and is rapidly cooled and solidified, and finally the alloy powder is collected in the powder collecting barrel, the alloy powder is placed in an electric vacuum drying oven (temperature is 80℃) for drying, and the dried alloy powder is obtained; then the dried alloy powder is ground and sieved to prevent powder agglomeration; finally, the ground and sieved alloy filler powder is transferred into a vacuum box for storage to prevent oxidation.

[0143] 2) The alloy powder and vanadium powder are ground in a mortar for 20 min to obtain a mixed powder.

[0144] 3) Before pressing, zinc stearate alcohol solution is applied to the inner wall of the mold and the upper and lower die loading surfaces, then the mixed powder is placed in the mold, and the mold is placed in an ultrasonic vibrator for oscillation for 10 min to make the powder evenly distributed in the mold cavity, the inner cavity diameter of the mold is 10 mm, a manual powder tablet press is used for loading pressure, the pressure maintaining time is 2 min, then the pressure is released and the mold is demolded, and a brazing foil with a thickness of 0.6 mm is prepared.

[0145] 4) Alumina ceramic substrates and oxygen-free copper substrates with a size of 10 mm x 10 mm x 2 mm are selected, the welding surface of the alumina ceramic is polished with 800# and 1000# metallographic sandpaper in turn, then the polished surface is immersed in an acetone solution for ultrasonic cleaning, finally the surface is washed with alcohol and blown dry to obtain the alumina ceramic substrate to be welded. The brazing foil is placed on the alumina ceramic, and the oxygen-free copper substrate is placed on the brazing foil to form an alumina ceramic substrate-brazing foil-oxygen-free copper substrate brazing assembly. A tungsten block with a pressure of 2 MPa is placed on the brazing assembly to ensure close contact between the assembly layers during brazing. Then it is sent into a vacuum tube furnace.

[0146] 5) The vacuum tube furnace is evacuated to 4 x 10 -3PA below, first at a rate of 10 ℃ / min to 300 ℃ for 15 min; then at a rate of 10 ℃ / min to 1260 ℃ for 25 min; finally at a rate of 10 ℃ / min to 300 ℃, natural cooling to room temperature after taking out, get the bonded alumina ceramic copper product.

[0147] Example 9

[0148] The embodiment is different from example 1 that the elemental powder only includes cobalt powder.

[0149] The composite filler metal includes the following components by mass percentage:

[0150] 40% of palladium copper vanadium cobalt manganese alloy powder and 60% of elemental powder; wherein the elemental powder is only cobalt powder, and the particle size of the cobalt powder is 80 μm.

[0151] The palladium copper vanadium cobalt manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese, and the balance is palladium.

[0152] The brazing method includes the following processes:

[0153] 1) Preparation of palladium copper vanadium cobalt manganese alloy powder. The palladium copper vanadium cobalt manganese is placed in a graphite crucible in a smelting furnace, the hearth temperature is set to 1800 ℃, and the alloy melt is placed in the tundish, and the alloy melt is atomized by applying 8 MPa high pressure argon gas. The alloy liquid drops into the cooling water at the bottom of the atomization barrel and is rapidly cooled and solidified. Finally, the alloy powder is collected by the powder collecting barrel, and the alloy powder is placed in an electric vacuum drying oven (temperature is 80 ℃) to obtain the dried alloy powder. Then the dried alloy powder is ground and sieved to prevent powder agglomeration. Finally, the ground and sieved alloy filler powder is transferred into a vacuum box for storage to prevent oxidation.

[0154] 2) The alloy powder and cobalt powder are placed in a mortar and ground for 20 min to obtain a mixed powder.

[0155] 3) Before pressing, the inner wall of the mold and the upper and lower mold punch loading surface need to be coated with zinc stearate alcohol solution, then the mixed powder is placed in the mold, and the powder is evenly distributed in the mold cavity by placing it in an ultrasonic vibrator for 10 min. The inner diameter of the mold is 10 mm, and the manual powder tablet press is used to load the pressure, and the pressure maintaining time is 2 min. Then, the pressure is released and the mold is removed, and the thickness of the brazing foil is 0.6 mm.

[0156] 4) Selecting the size specification of 10 mm x 10 mm x 2 mm of alumina ceramic substrate and oxygen-free copper substrate, the alumina ceramic to be welded surface is polished with 800# and 1000# metallographic sandpaper in turn, after polishing, it is immersed in acetone solution for ultrasonic cleaning, finally it is rinsed with alcohol and dried, obtaining the alumina ceramic substrate to be welded. The brazing filler metal foil is placed on the alumina ceramic, and then the oxygen-free copper substrate is placed on the brazing filler metal foil, forming the brazing assembly of alumina ceramic substrate-brazing filler metal foil-oxygen-free copper substrate. A tungsten block with a pressure of 2 MPa is placed on the brazing assembly to ensure the close contact between the assembly layers during brazing. Then it is sent into the vacuum tube furnace.

[0157] 5) The vacuum tube furnace is evacuated to 4 x 10 -3 Pa below, first heated to 300℃ at a rate of 10℃ / min and kept for 15 min; then heated to 1260℃ at a rate of 10℃ / min and kept for 25 min; finally, the temperature is decreased to 300℃ at a rate of 10℃ / min, and after natural cooling to room temperature, the alumina ceramic copper-clad product is obtained.

[0158] Example 10

[0159] The difference between this example and Example 1 is that the elemental powder only includes manganese powder.

[0160] The composite brazing filler metal includes the following components by mass percentage:

[0161] 40% of palladium-copper-vanadium-cobalt-manganese alloy powder and 60% of elemental powder; wherein the elemental powder is only manganese powder, and the particle size of the manganese powder is 80μm.

[0162] The palladium-copper-vanadium-cobalt-manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese, and the balance is palladium.

[0163] The brazing method includes the following processes:

[0164] 1) Preparation of palladium-copper-vanadium-cobalt-manganese alloy powder. The palladium-copper-vanadium-cobalt-manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800℃, and appropriate stirring is carried out during the smelting process. The alloy melt is placed in a tundish preheated to above 850℃, and high-pressure argon gas of 8 MPa is applied to atomize the alloy melt. The alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and are rapidly cooled and solidified. Finally, the alloy powder is collected in a powder collection barrel, and the alloy powder is dried in an electric vacuum drying oven (temperature 80℃) to obtain dried alloy powder. Then the dried alloy powder is ground and sieved to prevent powder agglomeration. Finally, the ground and sieved alloy brazing filler metal powder is transferred into a vacuum box for storage to prevent oxidation.

[0165] 2) Put the alloy powder and manganese powder into a mortar and grind for 20 min to obtain a mixed powder.

[0166] 3) Before pressing, the inner wall of the mold and the loading surface of the upper and lower dies are coated with a zinc stearate alcohol solution, then the mixed powder is placed in the mold and oscillated in an ultrasonic vibrator for 10 min to make the powder evenly distributed in the mold cavity. The inner cavity diameter of the mold is 10 mm, and the powder is pressed using a manual powder tablet press with a loading pressure. The pressure is maintained for 2 min, then released and demolded to obtain a brazing foil with a thickness of 0.6 mm.

[0167] 4) Select an alumina ceramic substrate and an oxygen-free copper substrate with a size of 10 mm x 10 mm x 2 mm. The welding surface of the alumina ceramic is polished with 800# and 1000# metallographic sandpaper, respectively, then immersed in an acetone solution for ultrasonic cleaning, and finally washed with alcohol and dried to obtain the alumina ceramic substrate to be welded. The brazing foil is placed on the alumina ceramic, and the oxygen-free copper substrate is placed on the brazing foil to form an alumina ceramic substrate-brazing foil-oxygen-free copper substrate brazing assembly. A tungsten block with a pressure of 2 MPa is placed on the brazing assembly to ensure close contact between the assembly layers during brazing. Then it is sent into a vacuum tube furnace.

[0168] 5) The vacuum tube furnace is evacuated to below 4 x 10 -3 pa, first heated to 300℃ at a rate of 10℃ / min and held for 15 min, then heated to 1260℃ at a rate of 10℃ / min and held for 25 min, and finally cooled to 300℃ at a rate of 10℃ / min, and naturally cooled to room temperature. The alumina ceramic copper-clad product is obtained.

[0169] Example 11

[0170] The difference between this example and Example 1 is that the elemental powder includes palladium powder, copper powder and manganese powder, and the mass ratio is 25:50:25.

[0171] The composite brazing filler metal includes the following components by mass percentage:

[0172] 40% of palladium-copper-vanadium-cobalt-manganese alloy powder and 60% of elemental powder; wherein the elemental powder includes palladium powder, copper powder and manganese powder, and the ratio of palladium powder, copper powder and manganese powder is 25:50:25, and the particle size of palladium powder, copper powder and manganese powder is 80μm, 40μm and 80μm respectively.

[0173] The palladium-copper-vanadium-cobalt-manganese alloy powder contains 20.5% palladium, 0.5% vanadium, 11.5% cobalt, 18.5% manganese, and the balance is copper.

[0174] The brazing method includes the following processes:

[0175] 1) Preparation of palladium copper vanadium cobalt manganese alloy powder. The palladium copper vanadium cobalt manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800℃, appropriate stirring is applied during the smelting process, the ladle is preheated to above 850℃, the alloy melt is placed in the ladle, and high-pressure argon gas of 8MPa is applied to atomize the alloy melt, the alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and are rapidly cooled and solidified, and finally the alloy powder is collected in the powder collecting barrel, the alloy powder is placed in an electric vacuum drying oven (temperature is 80℃) for drying, and the dried alloy powder is obtained; then the dried alloy powder is ground and sieved to prevent powder agglomeration; finally, the ground and sieved alloy filler powder is transferred into a vacuum box for storage to prevent oxidation.

[0176] 2) The alloy powder and each single element powder (palladium powder, copper powder, manganese powder) are ground in a mortar for 20min to obtain a mixed powder.

[0177] 3) Before pressing, zinc stearate alcohol solution is applied to the inner wall of the mold and the upper and lower mold punch loading surface, then the mixed powder is placed in the mold, and is oscillated in the ultrasonic vibration instrument for 10min to make the powder evenly distributed in the mold cavity, the inner cavity diameter of the mold used is 10mm, the manual powder tablet press is used for loading pressure, the pressure maintaining time is 2min, then the pressure is released and the mold is demolded, and the brazing filler metal foil with a thickness of 0.6mm is prepared.

[0178] 4) The size specification of the alumina ceramic substrate and oxygen-free copper substrate is 10mm×10mm×2mm, the welding surface of the alumina ceramic is polished with 800# and 1000# metallographic sandpaper in turn, is immersed in acetone solution for ultrasonic cleaning after polishing, and is finally washed with alcohol and blown dry to obtain the alumina ceramic substrate to be welded. The brazing filler metal foil is placed on the alumina ceramic, and the oxygen-free copper substrate is placed on the brazing filler metal foil to form an alumina ceramic substrate-brazing filler metal foil-oxygen-free copper substrate brazing assembly. A tungsten block with a pressure of 2MPa is placed on the brazing assembly to ensure the close contact between the assembly layers during brazing. Then it is sent into a vacuum tube furnace.

[0179] 5) The vacuum tube furnace is evacuated to below 4×10 -3 Pa, first heated to 300℃ at a rate of 10℃ / min and kept for 15min, then heated to 1260℃ at a rate of 10℃ / min and kept for 25min, and finally cooled to 300℃ at a rate of 10℃ / min, and taken out after natural cooling to room temperature to obtain the bonded alumina ceramic copper-clad product.

[0180] Example 12

[0181] The difference between this example and example 1 is that the particle size of each single element powder is the same as that of the palladium copper vanadium cobalt manganese alloy powder.

[0182] The composite filler comprises the following components by mass percentage:

[0183] 40% of palladium copper vanadium cobalt manganese alloy powder and 60% of elemental powder; wherein the elemental powder comprises palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder, and the ratio of the palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is 20:48:1:12:19, the average particle size of the palladium powder is 50-100 μm; the average particle size of the copper powder is 20-60 μm; the average particle size of the vanadium powder is 10-40 μm; the average particle size of the cobalt powder is 40-100 μm; and the average particle size of the manganese powder is 40-100 μm.

[0184] The palladium copper vanadium cobalt manganese alloy powder contains 20.5% of palladium, 0.5% of vanadium, 11.5% of cobalt, 18.5% of manganese and the balance of copper.

[0185] The brazing method comprises the following processes:

[0186] 1) preparing the palladium copper vanadium cobalt manganese alloy powder. The palladium copper vanadium cobalt manganese is placed in a graphite crucible and heated in a smelting furnace, the hearth temperature is set to 1800℃, appropriate stirring is performed during the smelting process, the pouring ladle is preheated to above 850℃, the alloy melt is placed in the pouring ladle, 8 MPa high-pressure argon gas is applied to atomize the alloy melt, the alloy liquid drops fall into the cooling water at the bottom of the atomization barrel and are rapidly cooled and solidified, and finally the alloy powder is collected in the powder collecting barrel, the alloy powder is placed in an electric vacuum drying oven (temperature 80℃) for drying to obtain the dried alloy powder; then the dried alloy powder is ground and sieved to prevent powder agglomeration; finally, the ground and sieved alloy filler powder is transferred into a vacuum box for storage to prevent oxidation.

[0187] 2) grinding the alloy powder and each elemental powder in a mortar for 20 min to obtain a mixed powder.

[0188] 3) before pressing, zinc stearate alcohol solution is applied to the inner wall of the mold and the upper and lower die loading surfaces, then the mixed powder is placed in the mold, placed in an ultrasonic vibrator for 10 min to make the powder evenly distributed in the mold cavity, the inner cavity diameter of the mold is 10 mm, a manual powder tablet press is used to load pressure, the pressure maintaining time is 2 min, then the pressure is released and the mold is demolded to obtain a brazing foil with a thickness of 0.6 mm.

[0189] 4) Selecting the size specification of 10 mm x 10 mm x 2 mm of alumina ceramic substrate and oxygen-free copper substrate, the alumina ceramic to be welded surface is polished with 800# and 1000# metallographic sandpaper in turn, after polishing, it is immersed in acetone solution for ultrasonic cleaning, finally it is rinsed with alcohol and dried, to obtain the alumina ceramic substrate to be welded. The brazing filler metal foil is placed on the alumina ceramic, and then the oxygen-free copper substrate is placed on the brazing filler metal foil, forming the brazing assembly of alumina ceramic substrate-brazing filler metal foil-oxygen-free copper substrate. A tungsten block with a pressure of 2 MPa is placed on the brazing assembly to ensure the close contact between the assembly layers during brazing. Then it is sent into the vacuum tube furnace.

[0190] 5) The vacuum tube furnace is evacuated to 4 x 10 -3 Pa below, first heated to 300℃ at a rate of 10℃ / min and kept for 15 min; then heated to 1260℃ at a rate of 10℃ / min and kept for 25 min; finally, the temperature is decreased to 300℃ at a rate of 10℃ / min, and after natural cooling to room temperature, it is taken out, to obtain the bonded alumina ceramic copper-clad product.

[0191] Comparative Example 1

[0192] Comparative Example 1 is different from Example 1 in that it only includes palladium-copper-vanadium-cobalt-manganese alloy powder.

[0193] Comparative Example 2

[0194] Comparative Example 1 is different from Example 1 in that it only includes elemental powder.

[0195] Comparative Example 3

[0196] Comparative Example 3 is different from Example 6 in that the elemental powder only includes aluminum powder.

[0197] Comparative Example 4

[0198] Comparative Example 4 is different from Example 1 in that the copper powder in the elemental powder is replaced by aluminum powder.

[0199] Test Example

[0200] The hardness, shear strength, elongation and thermal conductivity of the alumina ceramic copper-clad products finally prepared in each example and each comparative example are measured. The results are shown in Table 1.

[0201] Table 1: Index parameters of alumina ceramic copper-clad products prepared in each example and each comparative example

[0202]

[0203]

[0204] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A composite brazing filler metal for brazing alumina ceramic substrates and copper substrates, characterized in that, The components include the following percentages by mass: 20%~60% palladium-copper-vanadium-cobalt-manganese alloy powder and 40%~80% elemental powder; The palladium-copper-vanadium-cobalt-manganese alloy powder contains 20.5-21.5% palladium by mass, 0.5-1% vanadium by mass, 11.5-12.5% ​​cobalt by mass, 18.5-19.5% manganese by mass, and the balance is copper. The elemental powder comprises the following components in parts by mass: 16 to 24 parts palladium powder, 40 to 56 parts copper powder, 0.8 to 1.2 parts vanadium powder, 10 to 14 parts cobalt powder, and 15 to 23 parts manganese powder.

2. The composite brazing filler metal for brazing alumina ceramic substrates and copper substrates according to claim 1, characterized in that, The average particle size of the elemental powder is smaller than that of the palladium-copper-vanadium-cobalt-manganese alloy powder.

3. The composite brazing filler metal for brazing alumina ceramic substrate and copper substrate according to claim 2, characterized in that, The average particle size of the palladium-copper-vanadium-cobalt-manganese alloy powder is 100 mesh to 300 mesh. The palladium powder has an average particle size of 50 μm to 100 μm. The average particle size of the copper powder is 20 μm to 60 μm; The vanadium powder has an average particle size of 10 μm to 40 μm. The cobalt powder has an average particle size of 40 μm to 100 μm. The average particle size of the manganese powder is 40 μm to 100 μm.

4. The composite brazing filler metal for brazing alumina ceramic substrates and copper substrates according to claim 1, characterized in that, The purity of both the palladium-copper-vanadium-cobalt-manganese alloy powder and the elemental powder is greater than 99.5%.

5. A method for brazing an alumina ceramic substrate to a copper substrate, characterized in that, Includes the following processes: A palladium-copper-vanadium-cobalt-manganese alloy powder is provided, wherein the mass percentage content of each element in the palladium-copper-vanadium-cobalt-manganese alloy powder is as described in any one of claims 1 to 4; Provide an elemental powder, wherein the mass fractions of the elemental powder are as described in any one of claims 1 to 4; The palladium-copper-vanadium-cobalt-manganese alloy powder and the elemental powder are mixed in the proportions described in any one of claims 1 to 4 to obtain a mixed powder. The mixed powder is pressed into a brazing foil sheet; The brazing foil is placed at the brazing joint between the alumina ceramic substrate and the copper substrate to obtain a brazed assembly. The brazed assembly is then vacuum brazed to obtain the brazed assembly.

6. The method for brazing an alumina ceramic substrate to a copper substrate according to claim 5, characterized in that, The vacuum brazing Includes the following processes: The brazed assembly is placed in a vacuum environment and heated to 1090℃~1120℃ at a rate of 5℃ / min~10℃ / min, and held for 5min~15min. Then, it is heated to 1140℃~1260℃ at a rate of 5℃ / min~10℃ / min and held for 5min~25min. Finally, it is cooled to 300℃~320℃ at a rate of 5~10℃ / min and allowed to cool naturally to room temperature to obtain the brazed assembly.

7. The method for brazing an alumina ceramic substrate to a copper substrate according to claim 5, characterized in that, The thickness of the brazing foil is 0.2mm to 1.0mm.

8. The method for brazing an alumina ceramic substrate to a copper substrate according to claim 5, characterized in that, The method for preparing the palladium-copper-vanadium-cobalt-manganese alloy powder, Includes the following processes: Based on the mass percentage content of each element in the palladium-copper-vanadium-cobalt-manganese alloy powder, a mixture comprising palladium powder, copper powder, vanadium powder, cobalt powder and manganese powder is prepared. The mixture is melted to obtain an alloy melt; The alloy melt is atomized and granulated to obtain alloy droplets; The alloy droplets are cooled in a coolant to obtain alloy particles; The alloy particles are dried, ground, and sieved to obtain the palladium-copper-vanadium-cobalt-manganese alloy powder.

9. The method for brazing an alumina ceramic substrate to a copper substrate according to claim 8, characterized in that, The pressure for atomization granulation is 5 MPa to 10 MPa.

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