A method for preparing copper / molybdenum / copper multilayer composite material

Abstract

The present invention provides a method for preparing a copper / molybdenum / copper multilayer composite material, comprising: pre-treating copper and molybdenum plates for standby use; infiltration sintering the copper and molybdenum plates to obtain a multilayer copper / molybdenum / copper infiltration ingot; subjecting the obtained multilayer copper / molybdenum / copper infiltration ingot to direct current-assisted hot pressing sintering, applying an electric current vertically above the multilayer copper / molybdenum / copper infiltration ingot and allowing the current to completely pass through the interfaces of each layer of the multilayer copper / molybdenum / copper infiltration ingot to obtain a copper / molybdenum / copper multilayer composite material with good interface bonding; and rolling the multilayer copper / molybdenum / copper composite material after direct current-assisted hot pressing sintering, wherein the rolling process parameters are: temperature of 550°C to 630°C, holding time of 10 min to 20 min, total rolling deformation of 60% to 80%, and reduction per pass of 30% to 40%. The present invention makes it possible to produce a molybdenum-copper composite material with high thermal conductivity and low thermal expansion coefficient, and no oxides or interface inclusions are generated between the molybdenum and copper plates, thereby increasing the interface bonding strength.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of preparing layered composite materials, and in particular, to a method for preparing a copper / molybdenum / copper multilayer composite material. Background Art

[0002] With the continuous advancement of microelectronic packaging technology, high-density three-dimensional integration technology is increasingly used in various fields. The resulting high heat flux density environment poses greater challenges to the thermal management of microelectronic packaging. Therefore, in order to enhance the heat dissipation capacity of electronic devices, the selection of thermal management materials with excellent performance has become a hot topic in current research.

[0003] Copper / molybdenum / copper composite (CMC) is a layered structure consisting of a composite plate with copper layers of equal thickness on both sides and a molybdenum layer in the middle. Its coefficient of thermal expansion is similar to that of ceramic silicon wafers, enabling reliable connections with materials like silicon chips and avoiding connection failures caused by thermal expansion mismatches. As a third-generation electronic packaging material, CMC is widely used in packaging substrates, particularly in high-density, high-power electronic devices. Due to its excellent thermal conductivity, CMC is also used in thermal management applications such as heat sinks and cooling modules to ensure effective heat dissipation in high-heat flux environments.

[0004] Common preparation methods for CMC composite materials mainly include: hot pressing, rolling composite method, melt infiltration combined with rolling method, diffusion welding method, etc. However, there are disadvantages in the preparation process, such as molybdenum and copper do not dissolve in each other and the physical properties are very different. The laminated composite of molybdenum and copper mainly relies on mechanical meshing between atoms, and there is a large difference in plasticity between the two during the rolling process, and the deformation between the layers is not coordinated, resulting in defects such as interface cracking and delamination.

[0005] Traditional molybdenum-copper layered composite materials are generally prepared using complex processes, which are costly and cannot effectively solve the interface bonding problem. Therefore, it is necessary to propose a more suitable molybdenum-copper layered composite material preparation technology so that these two metals can play their respective advantages, thereby achieving the best use of them and expanding their engineering applications. Summary of the Invention

[0006] The embodiments described herein address the technical problems existing in the above-mentioned background technology and propose a method for preparing a copper / molybdenum / copper multilayer composite material.

[0007] The present invention prepares a Cu / Mo / Cu layered composite material (CMC layered composite material) by vertical integral melt infiltration combined with DC-assisted hot pressing sintering and rolling technology, which solves the problems of low interface bonding strength, uncoordinated interlayer deformation, and easy delamination of Cu / Mo / Cu layered composite materials prepared by existing methods. It has a high yield, few plate defects, and high thermal conductivity.

[0008] According to the present disclosure, a method for preparing a copper / molybdenum / copper multilayer composite material is provided, comprising the following steps:

[0009] Step 1: Pre-treat the copper plate and molybdenum plate for later use;

[0010] Step 2: Infiltration and sintering the pretreated copper plate and molybdenum plate to obtain a multi-layer copper / molybdenum / copper infiltration ingot;

[0011] Step 3: subjecting the multilayer copper / molybdenum / copper infiltration ingot obtained in Step 2 to direct current-assisted hot pressing sintering, applying a current vertically directly above the multilayer copper / molybdenum / copper infiltration ingot, and allowing the current to completely pass through the interfaces of each layer of the multilayer copper / molybdenum / copper infiltration ingot to obtain a copper / molybdenum / copper multilayer composite material with good interface bonding;

[0012] Step 4: The multilayer copper / molybdenum / copper composite material after DC-assisted hot pressing sintering is rolled, wherein the rolling process parameters are: temperature 550°C to 630°C, holding time 10 min to 20 min, total rolling deformation 60% to 80%, and reduction per pass 30% to 40%.

[0013] As a further illustration of the present disclosure, the pretreatment process in step 1 includes surface cleaning, sandblasting and pickling processes.

[0014] As a further illustration of the present disclosure, the sandblasting process uses quartz sand of 40# to 80#, a sandblasting pressure of 0.4 MPa to 0.6 MPa, a sandblasting angle of 45°, and a sandblasting time of 1 min to 2 min.

[0015] As a further illustration of the present disclosure, the pickling process is as follows: the copper plate and the molybdenum plate are immersed in a mixed pickling solution consisting of 10% to 13% nitric acid and 87% to 90% deionized water for 20 seconds to 40 seconds.

[0016] As a further illustration of the present disclosure, the process parameters of the infiltration sintering are: temperature 1200° C. to 1500° C., holding time 3 h to 5 h, and finally cooling to room temperature, with a protective atmosphere of hydrogen.

[0017] As a further illustration of the present disclosure, the process parameters of the DC-assisted hot pressing sintering are: temperature 500° C. to 900° C., pressure 20 MPa to 40 MPa, and holding time 10 min to 60 min.

[0018] Compared with the prior art, the technical solution disclosed in this disclosure has the following beneficial technical effects:

[0019] The present invention provides a process for preparing a multilayer copper / molybdenum / copper composite material. Molybdenum and copper do not dissolve in each other and have significantly different physical properties. This process effectively improves the interfacial bonding strength between the two, overcoming the current limitations of molybdenum-copper composite material preparation, including the difficulty in coordinated deformation between molybdenum-copper layers and the susceptibility to interface cracking. This enables the production of molybdenum-copper composite materials with high thermal conductivity and low thermal expansion coefficient. Furthermore, no oxides or interface inclusions are generated between the molybdenum and copper plates, thereby increasing the interfacial bonding strength.

[0020] The above description is only an overview of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical means of the embodiments of the present application, they can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It should be noted that the drawings described below only relate to some embodiments of the present disclosure and are not intended to limit the present disclosure.

[0022] Figure 1 A process flow chart of the preparation method of the multilayer copper / molybdenum / copper composite material provided by the present invention;

[0023] Figure 2 The micromorphology and EDS spectrum analysis diagram of the molybdenum-copper bonding interface in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0025] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] like Figure 1 As shown, the present disclosure proposes a method for preparing a copper / molybdenum / copper multilayer composite material, comprising the following steps:

[0027] Step 1, surface cleaning: The copper plate and the molybdenum plate were mechanically polished using 80#, 280#, 400#, 600#, 800#, 1000#, 1200#, 1500#, and 2000# sandpaper in sequence, and then immersed in acetone solution for ultrasonic cleaning, and then ultrasonically cleaned in deionized water and anhydrous ethanol;

[0028] In step 1, the copper and molybdenum plates were 30 mm × 40 mm in size and 1 mm thick. The specific cleaning process in an ultrasonic cleaner was as follows: ultrasonic cleaning with acetone solution for 1 to 5 minutes, ultrasonic cleaning with deionized water for 10 to 20 minutes, and ultrasonic cleaning with anhydrous ethanol for 10 to 20 minutes.

[0029] Step 2, sandblasting: sandblasting with a sandblasting machine;

[0030] In step 2, quartz sand of 40# to 80# is used in the sandblasting process, the sandblasting pressure is 0.4 MPa to 0.6 MPa, the sandblasting angle is 45°, and the sandblasting time is 1 min to 2 min.

[0031] Step 3, pickling: The sandblasted plate is immersed in a mixed pickling solution of nitric acid and deionized water at room temperature for 20 seconds to 40 seconds, and then ultrasonically cleaned again with anhydrous ethanol for 10 minutes to 20 minutes to obtain the pretreated copper and molybdenum plates;

[0032] In step 3, the components and contents of the pickling solution are: 10% to 13% nitric acid and 87% to 90% deionized water.

[0033] Step 4, infiltration: infiltration and sintering the plate after pickling and activation to obtain a multi-layer copper / molybdenum / copper infiltration ingot, which is then stored;

[0034] In step 4, the infiltration sintering process parameters are: temperature 1200°C to 1500°C, holding time 3 h to 5 h, and protective atmosphere of hydrogen.

[0035] Step 5, DC-assisted hot pressing sintering: DC-assisted hot pressing sintering is performed on the multilayer copper / molybdenum / copper composite material to obtain a composite material with good interface bonding under the coupling effect of "thermal-mechanical-electrical";

[0036] The process parameters of DC-assisted hot pressing sintering are: temperature 500℃ ~ 900℃, pressure 20 MPa ~ 40 MPa, and holding time 10 min ~ 60 min.

[0037] Step 6, rolling: rolling the multilayer copper / molybdenum / copper composite material after DC assisted hot pressing sintering;

[0038] The specific process of rolling treatment is: temperature 550℃ ~ 630℃, holding time 10 min ~ 20 min, total rolling deformation of 60% ~ 80%, and the reduction of each pass varies with the total thickness of the sample, which is 30% ~ 40%.

[0039] Step 7, post-processing: performing surface finishing on the rolled multi-layer copper / molybdenum / copper composite material, removing surface oxide scale and cleaning.

[0040] The infiltration method has the advantages of near-net shape and controllable process. In addition, the infiltration is carried out in a reducing atmosphere, which can avoid problems such as interface oxidation and inclusions, thereby obtaining a well-bonded interface with low thermal resistance. The microstructure of the material can be controlled by adjusting the infiltration parameters, such as the infiltration temperature and the holding time. During the infiltration process, liquid copper is injected into the surface of the solid molybdenum layer material in a molten state. The liquid copper forms a thin layer on the surface of the molybdenum layer, and due to the effect of surface tension, the liquid copper will expand on the surface of the molybdenum plate, filling the tiny pores on the surface. This surface tension-driven expansion helps to evenly distribute the liquid copper on the surface of the molybdenum plate.

[0041] DC-assisted hot pressing sintering can promote charge migration and thermal motion between materials and improve the density and crystal structure integrity of materials by introducing a DC electric field perpendicular to the sample, so that the current completely passes through the interfaces of each layer of the layered specimen. The action of the electric field helps to evenly distribute the grains, thereby improving the uniformity and consistency of the material. By adjusting the parameters of the DC electric field, the microstructure of the material, including grain size, crystal orientation, etc., can be precisely controlled to optimize the performance of the material, providing an efficient, energy-saving and controllable way to prepare high-performance materials. Due to the thermal stress generated by the temperature gradient between the surface and the interior of the metal, dislocation movement can be driven. The current can not only reduce the flow stress of the metal and improve the plastic forming ability, but also promote dynamic recrystallization and improve the cast microstructure after infiltration.

[0042] Hot rolling deformation treatment improves the interface bonding, reduces interface porosity and inclusions, and enhances the interlayer coordinated deformation capability of the composite material. Due to its lower flow stress and lower strain rate, thermal deformation has the effect of repairing unclosed pores and increasing relative density, thereby improving processing performance. At the same time, it significantly improves the hardness and strength of the material, and by forming a dense crystal structure, the material possesses superior mechanical properties. Accurate dimensional control is easier to achieve at high temperatures, allowing the final product to meet engineering requirements. Hot rolling helps to improve the uniformity of metal materials and eliminate the inhomogeneity of the internal structure and chemical composition of the material. Hot rolling can break up coarse grains, reduce defects such as voids that occur during infiltration, refine the grains, thereby improving its ability to resist deformation and enhancing the toughness of the material.

[0043] This invention uses vertical monolithic infiltration combined with DC-assisted hot pressing and rolling to produce a multilayer copper / molybdenum / copper composite material. The integration of these three key steps results in superior interfacial bonding and a higher yield. More importantly, the infiltrated ingot, after DC-assisted hot pressing and sintering, can be hot-rolled using a lower-temperature hot rolling process than conventional hot rolling temperatures, reducing the number of rolling passes and thus preventing excessive oxidation of the copper layer while minimizing uncoordinated deformation between the molybdenum and copper layers.

[0044] The present invention adopts the above-mentioned process method, firstly, the laminated component materials are melt-infiltrated to achieve liquid-solid bonding, so that the contact surfaces of the copper and molybdenum components are tightly bonded over the entire area, achieving a relatively ideal bonding strength; then the tightly bonded copper-molybdenum-copper composite plate is subjected to DC-assisted hot pressing sintering. Since the interface bonding strength between the laminates is high and a plane constraint is generated, the flow of metal during the hot pressing sintering process is restricted, causing the components to deform synchronously, thereby ensuring that the layer thickness ratio does not change with changes in sintering pressure. At the same time, the bonding area ratio between molybdenum and copper is further increased, resulting in good parallelism between the material laminates; through rolling deformation, the final thickness of the copper-molybdenum-copper composite plate can be accurately controlled, and the axial pressure and shear tensile effect generated during the rolling process further improve the interface bonding strength between molybdenum and copper.

[0045] The following describes the specific embodiments: Example

[0046] The surfaces of the three-layer copper plates and the two-layer molybdenum plates were mechanically polished and ultrasonically cleaned in the order of acetone, deionized water, and anhydrous ethanol. Subsequently, the surfaces were sandblasted at a pressure of 0.4 MPa and a distance of 10 mm at a 45° angle for 2 min. Subsequently, they were pickled in a mixed solution of 10% nitric acid and 90% deionized water for 40 s and then washed with anhydrous ethanol for 10 min to obtain the pretreated plates.

[0047] The pretreated plates were stacked and then infiltrated and sintered. The specific process parameters were: temperature 1200℃, holding time 5 h, and protective atmosphere of hydrogen. Then, they were subjected to DC assisted hot pressing sintering. The specific process parameters were: temperature 900℃, holding time 10 min, and pressure 20 MPa. After that, they were hot rolled. The specific process parameters were: temperature 550℃, holding time 20 min, 30% reduction per pass, two rolling passes, and a total rolling deformation of 60%. Then, they were post-treated to remove the oxide scale and perform surface finishing to obtain a five-layer copper / molybdenum / copper composite material. The interface of the obtained five-layer copper / molybdenum / copper composite material was observed and EDS energy spectrum analysis was performed on the interface, as shown in the following figure. Figure 2 As shown in the figure, the molybdenum grains are finer and the interface inclusions are reduced. The content of elements Mo and Cu in the interface is the highest, and the transition layer is thinner. Example

[0048] The surfaces of the four-layer copper plate and the three-layer molybdenum plate were mechanically polished and ultrasonically cleaned in the order of acetone, deionized water, and anhydrous ethanol. Subsequently, the surfaces were sandblasted at a pressure of 0.6 MPa and a distance of 10 mm at a 45° angle for 1 min. Subsequently, they were immersed in a mixed solution of 13% nitric acid and 87% deionized water for 20 s, and then washed with anhydrous ethanol for 20 min to obtain the pretreated plates.

[0049] The pretreated plates were stacked and then infiltrated and sintered. The specific process parameters were: temperature 1500℃, holding time 3 hours, and protective atmosphere of hydrogen. The infiltrated ingots were then subjected to DC-assisted hot pressing sintering. The specific process parameters were: temperature 500℃, holding time 60 minutes, and pressure 40 MPa. They were then hot rolled. The specific process parameters were: temperature 600℃, holding time 15 minutes, 35% reduction per pass, two rolling passes, and a total rolling deformation of 70%. They were then post-treated to remove oxide scale and perform surface finishing to obtain a seven-layer copper / molybdenum / copper composite material. Example

[0050] The surfaces of the 5-layer copper plate and the 4-layer molybdenum plate were mechanically polished and ultrasonically cleaned in the order of acetone, deionized water, and anhydrous ethanol. Subsequently, the surfaces were sandblasted at a pressure of 0.5 MPa and a distance of 10 mm at a 45° angle for 2 min. Subsequently, they were immersed in a mixed solution of 10% nitric acid and 90% deionized water for 30 s, and then washed with anhydrous ethanol for 10 min to obtain the pretreated plates.

[0051] The pretreated plates were stacked and then infiltrated and sintered. The specific process parameters were: temperature 1300℃, holding time 4 h, and protective atmosphere of hydrogen. The infiltrated ingots were then subjected to DC-assisted hot pressing sintering. The specific process parameters were: temperature 700℃, holding time 30 min, and pressure 30 MPa. They were then hot rolled. The specific process parameters were: temperature 630℃, holding time 10 min, 40% reduction per pass, two rolling passes, and a total rolling deformation of 80%. They were then post-treated to remove oxide scale and perform surface finishing to obtain a nine-layer copper / molybdenum / copper composite material.

[0052] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a copper / molybdenum / copper multilayer composite material, characterized in that: The steps include: Step 1: Pre-treat the copper plate and molybdenum plate for later use; Step 2: Infiltration and sintering the pretreated copper and molybdenum plates to obtain a multilayer copper / molybdenum / copper infiltration ingot. The infiltration and sintering process parameters are: temperature 1200°C to 1500°C, holding time 3 h to 5 h, and finally cooling to room temperature. The protective atmosphere is hydrogen. Step 3: subjecting the multilayer copper / molybdenum / copper infiltration ingot obtained in Step 2 to direct current-assisted hot pressing sintering, applying a current vertically directly above the multilayer copper / molybdenum / copper infiltration ingot, and allowing the current to completely pass through the interfaces of each layer of the multilayer copper / molybdenum / copper infiltration ingot to obtain a copper / molybdenum / copper multilayer composite material with good interface bonding; Step 4: The multilayer copper / molybdenum / copper composite material after DC-assisted hot pressing sintering is rolled, wherein the rolling process parameters are: temperature 550°C to 630°C, holding time 10 min to 20 min, total rolling deformation 60% to 80%, and reduction per pass 30% to 40%.

2. The method according to claim 1, characterized in that The pretreatment process in step 1 includes surface cleaning, sandblasting and pickling processes.

3. The method according to claim 2, wherein The sandblasting process uses quartz sand of 40# to 80#, the sandblasting pressure is 0.4 MPa to 0.6 MPa, the sandblasting angle is 45°, and the sandblasting time is 1 min to 2 min.

4. The method according to claim 2, wherein The pickling process is as follows: immersing the copper plate and the molybdenum plate in a mixed pickling solution consisting of 10% to 13% nitric acid and 87% to 90% deionized water for 20 seconds to 40 seconds.

5. The method according to claim 1, wherein The process parameters of the DC-assisted hot pressing sintering are: temperature 500°C to 900°C, pressure 20 MPa to 40 MPa, and holding time 10 min to 60 min.

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