Gradient alloy skeleton reinforced composite solder and preparation method and application thereof

Abstract

The invention discloses a gradient alloy skeleton reinforced composite solder and a preparation method and application thereof. The gradient alloy skeleton reinforced composite solder is formed by compounding a component gradient alloy skeleton with a core-shell structure and a solder, wherein the component gradient alloy skeleton with the core-shell structure is filled with the solder; wherein the component gradient alloy framework with the core-shell structure comprises a metal framework and a Cu-Ni alloy coating layer. According to the gradient alloy skeleton reinforced composite solder, the high-melting-point metal skeleton on the inner layer serves as a slow reaction phase to keep a complete skeleton structure in the welding process, the good double-interpenetration reinforcing effect can be achieved, and the effect of supporting a weld joint can also be achieved; and the Cu-Ni alloy coating layer on the outer layer quickly reacts with the welding flux to form fine and dispersed metallurgical reaction particles, so that a good dispersion strengthening effect on a welding seam is achieved, and the reliability of a joint is improved through the combined action.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding materials, in particular to a gradient alloy framework reinforced composite solder as well as a preparation method and application thereof. BACKGROUND

[0002] In recent years, electronic devices such as satellites and radars are developing rapidly in the direction of integrated functions and miniaturization, which puts forward higher requirements for the welding stability and reliability of electronic device joints. In order to ensure the long-term service of the device under high frequency and high current density, and meet the application requirements of low-temperature connection and high-temperature service of the joint, it is urgent to develop new composite solders to realize the precision control of device welding and obtain high welding rate and high strength joints.

[0003] One of the effective methods to solve the above problems is to introduce a framework reinforcing phase into the solder. Chinese patent CN116493804A discloses a composite formed whole metal mesh reinforced solder and a preparation method thereof. The method deposits a metal layer on the surface of the metal mesh and performs alloying under vacuum, obtains a laminated structure in the order of solder sheet, alloy mesh and solder sheet, and embeds the solder cladding by rolling. However, the method mainly has the following problems: after high-temperature alloying, the whole alloy mesh is in a uniform alloy state, and during the brazing process and after the brazing process, the whole alloy mesh is easy to be dissolved and broken, which reduces the reliability of the joint.

[0004] Therefore, it is urgent to propose a new metal mesh reinforced solder and a preparation method thereof to solve the above problems. SUMMARY

[0005] The present application aims to overcome the above technical deficiencies and proposes a gradient alloy framework reinforced composite solder as well as a preparation method and application thereof, which solves the technical problem in the prior art that after high-temperature alloying, the whole metal mesh is in a uniform alloy state, and during the brazing process and after the brazing process, the whole alloy mesh is easy to be dissolved and broken, which reduces the reliability of the joint.

[0006] In a first aspect, the present application provides a gradient alloy framework reinforced composite solder, which is composed of a composition gradient alloy framework with a core-shell structure and a solder, and the solder is filled in the composition gradient alloy framework with a core-shell structure; wherein the composition gradient alloy framework with a core-shell structure comprises a metal framework and a Cu-Ni alloy cladding layer.

[0007] In a second aspect, the present application provides a preparation method of a gradient alloy framework reinforced composite solder, which comprises the following steps: providing a metal mesh with a Cu and / or Ni metal layer on the surface; sintering the metal mesh with a Cu and / or Ni metal layer on the surface at high temperature to obtain an alloy mesh with a Cu-Ni alloy cladding layer on the surface; The gradient alloy framework reinforced composite solder is prepared by the following steps: filling molten solder into an alloy mesh with a Cu-Ni alloy cladding layer on the surface by an impregnation process, and then pressing.

[0008] In a third aspect, the present application provides application of the above-mentioned gradient alloy framework reinforced composite solder in precision device connection.

[0009] Compared with the prior art, the present application has the following beneficial effects: In the gradient alloy framework reinforced composite solder of the present application, the high-melting-point metal framework in the inner layer remains an intact framework structure as a slow reaction phase during the welding process, which not only plays a good "double interpenetration" strengthening role, but also plays a supporting role for the weld; the Cu-Ni alloy cladding layer in the outer layer rapidly reacts with the solder to form fine and dispersed metallurgical reaction particles, which play a good dispersion strengthening role for the weld, and together improve the reliability of the joint. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 The figure shows the component structure of an embodiment of the gradient alloy framework reinforced composite solder provided by the present application; Figure 2 The figure shows the cross-sectional micrograph of the gradient alloy framework reinforced composite solder prepared in Example 1 of the present application; Figure 3 The figure shows the stress-strain curve of the gradient alloy framework reinforced composite solder prepared in Example 1 of the present application; Figure 4 The figure shows the cross-sectional micrograph and element line scanning result of the gradient alloy framework reinforced composite solder prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0012] In a first aspect, referring to Figure 1 The present application provides a gradient alloy framework reinforced composite solder, which is composed of a component gradient alloy framework with a core-shell structure and solder, and the solder is filled in the component gradient alloy framework with a core-shell structure; wherein the component gradient alloy framework with a core-shell structure comprises a metal framework and a Cu-Ni alloy cladding layer.

[0013] In the present application, the gradient alloy framework reinforced composite solder is a composition gradient alloy framework reinforced composite solder with a core-shell structure. The high-melting-point metal framework in the inner layer acts as a slow reaction phase to maintain the integrity of the framework structure during the welding process, enhance the strength and toughness of the composite solder and its brazed joint, and control the precision of the weld; the Cu-Ni alloy cladding layer in the outer layer rapidly reacts with the low-melting-point solder to form fine and dispersed metallurgical reaction particles, which have a good dispersion strengthening effect on the weld, and together improve the reliability of the joint (compared with the same specification alloy mesh reinforced composite solder brazed joint, the strength is significantly improved).

[0014] In the present embodiment, the material of the metal framework is at least one of Ni, Cu, Fe, Cr, Ti, and stainless steel.

[0015] In the present embodiment, the solder is at least one of Sn-based alloy, In-based alloy, and Ga-based alloy.

[0016] In a second aspect, the present application provides a preparation method of a gradient alloy framework reinforced composite solder, comprising the following steps: S1, providing a metal mesh with a Cu and / or Ni metal layer on the surface; S2, sintering the metal mesh with a Cu and / or Ni metal layer on the surface at high temperature to obtain an alloy mesh with a Cu-Ni alloy cladding layer on the surface; S3, filling the molten solder into the alloy mesh with the Cu-Ni alloy cladding layer on the surface by infiltration process, and then pressing to obtain a gradient alloy framework reinforced composite solder.

[0017] In the present application, the molten low-melting-point solder is filled into the alloy mesh by the infiltration process, and the high-activity Cu-Ni alloy cladding layer is metallurgically combined with the molten solder, thereby enhancing the bonding strength between the reinforcing framework and the solder; the composite solder is pressed to a predetermined thickness by pressing, so as to realize the controllable thickness of the solder and make the surface of the solder flat, thereby improving the welding rate. In the prior art, a metal foil and a metal mesh are used to form a sandwich structure, and the initial thickness of the solder sheet is large, which requires higher rolling pressure and larger pressing amount, which may cause deformation or even breakage of the alloy mesh; in the present application, the molten solder can control the initial thickness of the solder sheet to be close to the target thickness of rolling, which not only avoids deformation or even breakage of the alloy mesh when the rolling pressure is too high, but also avoids low bonding strength between the solder and the alloy mesh when the rolling pressure or temperature is too low.

[0018] In the present embodiment, the metal mesh with a Cu and / or Ni metal layer on the surface is obtained by the following steps: Cu and / or Ni metal layer is deposited on the surface of the metal mesh to obtain a metal mesh with a Cu and / or Ni metal layer on the surface.

[0019] Further, the metal mesh is pretreated before use, and the pretreatment method comprises: cleaning the metal mesh by dilute hydrochloric acid, ethanol and water.

[0020] Further, the metal mesh is made of one of Ni, Cu, Fe, Cr, Ti and stainless steel. Those skilled in the art can understand that, if the metal mesh is made of Ni or Cu, the metal mesh surface at least corresponds to one of a Cu metal layer or a Ni metal layer; if the metal mesh is made of Fe, Cr, Ti or stainless steel, the metal mesh surface simultaneously has a Cu metal layer and a Ni metal layer.

[0021] Further, the thickness of the metal mesh is 0.05-0.2 mm, and the mesh number is 100-400.

[0022] Further, the deposition method is at least one of chemical plating, electrochemical deposition, physical vapor deposition and chemical vapor deposition.

[0023] In the embodiment, the weight percentage of the Cu and / or Ni metal layer in the metal mesh with the Cu and / or Ni metal layer on the surface is 5%-90%, including but not limited to 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and the like.

[0024] In the embodiment, the step of high-temperature sintering the metal mesh with the Cu and / or Ni metal layer on the surface comprises: placing the metal mesh with the Cu and / or Ni metal layer on the surface between pressing plates and performing high-temperature sintering. In the present application, the metal mesh is uniformly heated by being placed between the pressing plates, and finally a composite solder with uniform transverse composition distribution is obtained, thereby improving the soldering rate.

[0025] Further, the pressing plate is a plate material on the surface of which molten solder is poorly wetted. The present application does not limit the material of the pressing plate, and those skilled in the art can select according to the actual situation, as long as the above requirements can be met. For example, the pressing plate can be a quartz plate and the like.

[0026] Further, the number of the pressing plates is ≥2.

[0027] In the embodiment, the temperature of high-temperature sintering is 400-600℃, and the time of high-temperature sintering is 5-20 min. By controlling the weight percentage of the metal layer, the temperature and time of high-temperature sintering, the Cu-Ni alloy cladding layer is formed, and the original metal mesh is partially retained, so that the composition gradient alloy framework with core-shell structure is obtained, and the composite solder is prepared on this basis. If the time and temperature of high-temperature sintering are too high, the alloying will be excessive, the inner layer of the alloy framework will be alloyed, and will be quickly consumed in the welding process, losing the skeleton strengthening effect and reducing the joint strength. If the time and temperature of high-temperature sintering are too low, the alloying will be insufficient, and the outer layer of the alloy framework will not form an alloy layer, so that the composite solder strength is reduced, the metallurgical reaction rate is low in the welding process, the welding time is prolonged, and defects such as voids and cracks are easily formed, thereby reducing the joint strength and the welding rate.

[0028] In the embodiment, the process of high-temperature sintering is carried out in a protective atmosphere. In the present application, by directly carrying out high-temperature sintering in a protective atmosphere, the oxidation of the alloy mesh or the introduction of impurities is avoided, the vacuum time is saved, and the production efficiency is improved. At the same time, the alloy mesh is avoided to be switched in different devices, and the pollution risk is reduced.

[0029] Specifically, the protective atmosphere is at least one of a reducing gas, nitrogen or an inert gas. The present application does not limit the type of protective atmosphere, and those skilled in the art can select according to the actual situation.

[0030] The present application does not limit the temperature of the molten solder, and those skilled in the art can select according to the actual situation (such as the type of solder). In some specific embodiments of the present application, the temperature of the molten solder is 240-260℃.

[0031] In the embodiment, the infiltration process is at least one of pressure infiltration, vacuum infiltration, vacuum pressure infiltration and capillary infiltration.

[0032] In the embodiment, the step of filling the molten solder into the alloy mesh with a Cu-Ni alloy cladding layer on the surface by the infiltration process, and then pressing to obtain the gradient alloy framework reinforced composite solder includes: placing the alloy mesh with a Cu-Ni alloy cladding layer on the surface into a mold and immersing it into the molten solder, applying pressure to the mold to make the molten solder infiltrate into the grid gap, maintaining the pressure during the process of taking out the mold until the solder solidifies, and pressing after cooling to room temperature.

[0033] The present application does not limit the type of mold, and those skilled in the art can select according to the actual situation. In some specific embodiments of the present application, a spring press rod and a positioning groove are arranged on the mold to apply pressure to the mold, and further control the thickness of the composite solder after solidification.

[0034] wherein a pressure of 8-15 MPa is applied to the mold.

[0035] wherein the thickness of the composite solder after solidification is increased by 5-15 µm relative to the thickness of the alloy mesh having a Cu-Ni alloy cladding layer on the surface.

[0036] In the present embodiment, rolling process is adopted for pressing.

[0037] In the present embodiment, after pressing, the pressing ratio of the gradient alloy framework reinforced composite solder is 1%-30%, including but not limited to 1%, 3%, 5%, 7%, 10%, 15%, 20%, 25%, 30%, etc., wherein the pressing ratio is the ratio of the pressing amount to the initial thickness before pressing (the thickness of the composite solder after solidification).

[0038] In a third aspect, the present application provides the use of the above-mentioned gradient alloy framework reinforced composite solder in the connection of precision devices (such as microwave high-frequency components, etc.).

[0039] To avoid redundancy, in the following examples and comparative examples of the present application, the performance test methods involved are as follows: Micro-morphology test: field emission scanning electron microscope (SEM, JSM7500F) is used to test the micro-morphology of the cross section of the composite solder.

[0040] Component analysis test: cut 3 mm x 3 mm samples at three random points on the composite solder and place them in a beaker, add 25 mL of water, 1 mL of hydrochloric acid, and 5 mL of nitric acid, heat to dissolve completely at low temperature, cool to room temperature, then add various element standard storage solutions, and use ICP-OES for component analysis.

[0041] Tensile test: according to GB / T 228.1-2021, 5 samples of the composite solder are taken for tensile test.

[0042] Joint bonding rate test: according to GB / T 19943-2005, X-ray detection system is used to test the joint bonding rate, the bonding area in the X-Ray scanning micrograph is calculated, the composite solder is used to braze 10 mm x 10 mm surface modified aluminum alloy joints at 250℃, 0.03 MPa for 5 min, and the number of joints is 5.

[0043] Shear strength test: according to GB / T 11363-2008, shear test is performed on the above-mentioned 5 joints.

[0044] Example 1 A preparation method of a gradient alloy framework reinforced composite solder, the steps are as follows: In this embodiment, 250 mesh plain nickel mesh was selected as the metal skeleton, the mesh wire diameter was 0.045 mm, the mesh hole spacing was 0.0566 mm, and the surface was plated with a Cu plating layer with a mass fraction of 10%; the solder was Sn-3Ag-0.5Cu (SAC305) alloy solder produced by Alpha Company, and the specific preparation steps were as follows: (1) Put the 250 mesh plain nickel mesh with a size of 100 mm x 200 mm x 0.09 mm into a dilute hydrochloric acid with a molar concentration of 10%, clean it with anhydrous ethanol and deionized water by using an ultrasonic machine for 5 min, then put it into an electroplating solution with a constant temperature of 45°C for electroplating, the electroplating solution is a pyrophosphate system electroplating solution, the main salt is copper pyrophosphate (75 g / L), the complexing agent is potassium pyrophosphate (310 g / L), the buffer is ammonium citrate (40 g / L), the solvent is water, and the pH value of the electroplating solution is controlled between 8-9. The metal mesh is the cathode, the copper rod is the anode, the current density is 4 A / dm 2 , and the electroplating time is 17 min 20 s.

[0045] (2) After cleaning the plain nickel mesh with a Cu plating layer on the surface, place it between two quartz plates and put it into a vacuum tube furnace for alloying in a protective gas Ar, the alloying temperature is 500°C, and the time is 10 min.

[0046] (3) Put the alloy mesh into the mold and immerse it into the molten tin pool, the temperature in the pool is 250°C, apply a pressure of 10 MPa to the mold to make the molten solder penetrate into the mesh gap, maintain the pressure during the process of the mold leaving the molten tin pool until the solder solidifies, and the thickness of the composite solder after solidification is 0.104 mm, which increases by about 0.01 mm compared with the thickness of the alloy mesh. After cooling to room temperature, use a double-roller tablet press to roll the composite solder to 0.1 mm.

[0047] The cross-sectional micrograph of the gradient alloy skeleton reinforced composite solder prepared in this embodiment is shown in Figure 2 , and the metal skeleton and the solder are tightly combined. The composition analysis results show that the composition deviation is not more than 4%, which proves that the composite solder prepared in this embodiment has good composition uniformity. The stress-strain curve obtained by tensile test is shown in Figure 3 , and the average tensile strength reaches 88.02 MPa. The composite solder prepared in this embodiment is used to braze 10 mm x 10 mm surface modified aluminum alloy joints, and the average bonding rate of 5 joints is 99.94%, and the average shear strength of 5 joints reaches 67.69 MPa.

[0048] Example 2 A method for preparing a gradient alloy skeleton reinforced composite solder, the steps are as follows: In this embodiment, 250 mesh plain nickel mesh was selected as the metal skeleton, the mesh wire diameter was 0.045 mm, the mesh spacing was 0.0566 mm, and the surface was plated with a 30 wt.% Cu plating layer; the solder was Sn-3Ag-0.5Cu (SAC305) alloy solder produced by Alpha Company, and the specific preparation steps were as follows: (1) Put the 250 mesh plain nickel mesh with a size of 100 mm x 200 mm x 0.09 mm into a 10% molar concentration dilute hydrochloric acid, clean it with ultrasonic machine for 5 min, and then clean it with anhydrous ethanol and deionized water, and then put it into an electroplating solution with a constant temperature of 45°C for electroplating. The electroplating solution is a pyrophosphate system electroplating solution, the main salt is copper pyrophosphate (75 g / L), the complexing agent is potassium pyrophosphate (310 g / L), the buffer is ammonium citrate (40 g / L), and the solvent is water. The pH value of the electroplating solution is controlled between 8-9. The metal mesh is the cathode, the copper rod is the anode, the current density is 4 A / dm 2 , and the electroplating time is 20 min 50 s.

[0049] (2) After cleaning the plain nickel mesh with a Cu plating layer on the surface, place it between two quartz plates and put it into a vacuum tube furnace for alloying in a protective gas Ar, the alloying temperature is 600°C, and the time is 10 min.

[0050] (3) Put the alloy mesh into the mold and immerse it into the molten tin pool, the temperature in the pool is 250°C, apply a pressure of 10 MPa to the mold to make the molten solder penetrate into the mesh gap, maintain the pressure during the process of the mold leaving the molten tin pool until the solder solidifies, and the thickness of the composite solder after solidification is 0.108 mm, which increases by about 0.01 mm compared with the thickness of the alloy mesh. After cooling to room temperature, use a double-roller tablet press to roll the composite solder to 0.1 mm.

[0051] The cross-sectional micrograph and line scan results of the gradient alloy skeleton reinforced composite solder prepared in this embodiment are shown in Figure 4 , and the alloy mesh forms a gradient distribution of components. The component analysis results show that the component deviation is not more than 4%, which proves that the composite solder prepared in this embodiment has good component uniformity. The tensile test results show that the average tensile strength of 5 samples reaches 90.4 MPa. The 10 mm x 10 mm surface modified aluminum alloy joints are brazed using the composite solder prepared in this embodiment, and the average brazing rate of 5 joints is 99.87%, and the average shear strength of 5 joints reaches 67.95 MPa.

[0052] Example 3 A method for preparing a gradient alloy skeleton reinforced composite solder, the steps are as follows: In this embodiment, 180 mesh plain copper net is selected as the metal skeleton, the grid wire diameter is 0.05 mm, the mesh spacing is 0.09 mm, the surface is plated with 10 wt.% Ni coating, and the solder is Sn-3Ag-0.5Cu (SAC305) alloy solder produced by Alpha Company. The specific preparation steps are as follows: (1) Put the 180 mesh plain copper net with a size of 100 mm x 200 mm x 0.1 mm into 10% dilute hydrochloric acid, clean it with ultrasonic machine for 5 min, and then clean it with anhydrous ethanol and deionized water, respectively. Then put it into an electroplating solution with a constant temperature of 45°C for electroplating. The composition of the electroplating solution is nickel sulfate hexahydrate (240 g / L), nickel chloride hexahydrate (40 g / L) and boric acid (30 g / L), and the solvent is water. The metal net is the cathode, and the nickel rod is the anode. The current density is 4 A / dm 2 , and the electroplating time is 17 min 23 s.

[0053] (2) After cleaning the plain copper net with Ni coating on the surface, place it between two quartz plates and put it into a vacuum tube furnace for alloying in the protective gas Ar. The alloying temperature is 600°C, and the time is 10 min.

[0054] (3) Put the alloyed net into a mold and immerse it in a molten tin pool with a temperature of 250°C. Apply a pressure of 10 MPa to the mold to allow the molten solder to penetrate into the grid gap. Maintain the pressure during the process of the mold leaving the molten tin pool until the solder solidifies. The thickness of the composite solder after solidification is 0.114 mm, which increases by about 0.01 mm compared to the thickness of the alloyed net. After cooling to room temperature, use a double roller sheeting machine to roll the composite solder to 0.11 mm.

[0055] The composition analysis results show that the composition deviation is not more than 4%, which proves that the gradient alloy skeleton reinforced composite solder prepared in this embodiment has good composition uniformity. The tensile test results show that the average tensile strength of the 5 samples reaches 88.12 MPa. The composite solder prepared in this embodiment is used to solder 10 mm x 10 mm surface modified aluminum alloy joints, and the average bonding rate of the 5 joints is 99.54%, and the average shear strength of the 5 joints reaches 67.39 MPa.

[0056] Comparative Example 1 Compared with Example 1, the only difference is that in step (2), no quartz plate is used, and step (2) is as follows: (2) Clean the plain copper net with Cu coating on the surface, and directly put it into a vacuum tube furnace for alloying in the protective gas Ar. The alloying temperature is 500°C, and the time is 10 min.

[0057] The component analysis result shows that the component deviation reaches 4.32%, which indicates that the quartz plate has a good promoting effect on the component uniformity of the gradient alloy framework. The tensile test result shows that the average tensile strength of the 5 samples reaches 85.49 MPa. The average bonding rate of the 5 joints of the 10 mm x 10 mm surface modified aluminum alloy joint brazed by the composite solder prepared by the present comparative example is 95.32%, which indicates that the quartz plate is beneficial to uniformly heat the alloy net and obtain the composite solder with uniform transverse component distribution, thereby improving the average bonding rate of the joint.

[0058] Comparative Example 2 Compared with Example 1, the only difference is that the sintering temperature in step (2) is too low and the time is too short, and step (2) is as follows: (2) After cleaning the plain nickel net with Cu plating layer on the surface, the net is placed between two quartz plates, and is put into a vacuum tube furnace to perform alloying in a protective gas Ar, the alloying temperature is 300℃, and the time is 5 min.

[0059] The tensile test result shows that the average tensile strength of the 5 samples is 70.5 MPa. The 10 mm x 10 mm surface modified aluminum alloy joint brazed by the composite solder prepared by the present comparative example has an average bonding rate of 87.65% for the 5 joints, and an average shear strength of 60.15 MPa for the 5 joints. The above results show that the low alloying time and temperature are not conducive to improving the strength and bonding rate of the composite solder, and the reason may be that the low alloying time and temperature will lead to insufficient alloying, no alloy layer is formed on the outer layer of the framework, the metallurgical reaction rate is low, the welding time is prolonged, and defects such as void cracks are easily formed, thereby reducing the joint strength and bonding rate.

[0060] Comparative Example 3 Compared with Example 1, the only difference is that the sintering temperature and time in step (2) are too high, and step (2) is as follows: (2) After cleaning the plain nickel net with Cu plating layer on the surface, the net is placed between two quartz plates, and is put into a vacuum tube furnace to perform alloying in a protective gas Ar, the alloying temperature is 850℃, and the time is 30 min.

[0061] The tensile test results show that the average tensile strength of the 5 samples is 76.42 MPa. The composite solder prepared by the present comparative example is used to solder the 10 mm x 10 mm surface modified aluminum alloy joints, and the average welding rate of the 5 joints is 88.89%, and the average shear strength of the 5 joints is 58.34 MPa. The above results show that the alloying time and temperature that are too high are not conducive to improving the strength and welding rate of the composite solder, and the reason may be that if the alloying time and temperature are too high, the alloying will be excessive, the inner layer of the alloy skeleton will be alloyed, and will be consumed quickly during the welding process, losing the skeleton strengthening effect, and the joint strength will decrease; at the same time, the skeleton is completely alloyed, and is consumed by reaction during the welding process, forming a cavity, resulting in a decrease in the welding rate.

[0062] Comparative Example 4 Compared with Example 1, the only difference is that in step (3), the solder foil and the alloy mesh are combined in a laminated manner, and step (3) is as follows: (3) The SAC305 solder produced by Alpha Company is rolled into a solder foil with a thickness of 0.04 mm, and it is combined with the alloy mesh into a laminated structure of solder foil, alloy mesh, and solder foil. The press head of the heating press is used to make the solder embedded in the alloy mesh, and the solder is rolled to 0.1 mm.

[0063] The composition analysis results show that the composition deviation is not more than 4%, indicating that the composite solder prepared by the present comparative example has good composition uniformity. The tensile test results show that the average tensile strength of the 5 samples is 71.68 MPa, and the reason is that the laminated method is used, the solder and the alloy mesh are prone to peeling, the bonding strength is low, and the tensile strength of the composite solder is reduced. The composite solder prepared by the present comparative example is used to solder the 10 mm x 10 mm surface modified aluminum alloy joints, and the average welding rate of the 5 joints is 93.41%, which further indicates that the bonding strength between the skeleton and the matrix of the composite solder prepared by the laminated method is low, resulting in low tensile strength of the composite solder, and defects such as cavity cracks are prone to occur, reducing the joint welding rate.

[0064] Comparative Example 5 Compared with Example 1, the only difference is that in step (3), the infiltrated solder is not rolled after the infiltration, and a solder sheet is directly obtained, and step (3) is as follows: (3) The alloy mesh is placed in a mold and immersed in a molten tin pool with a temperature of 250℃. A pressure of 10 MPa is applied to the mold to make the molten solder infiltrate into the grid gap. The pressure is maintained during the process of the mold leaving the molten tin pool until the solder solidifies. After solidification, the thickness of the composite solder is 0.104 mm.

[0065] The component analysis result shows that the component deviation is not more than 4%, which proves that the composite solder prepared by the present comparative example has good component uniformity. The tensile test result shows that the average tensile strength of 5 samples reaches 87.04 MPa. The composite solder prepared by the present comparative example is used to braze 10 mm x 10 mm surface modified aluminum alloy joints, and the average bonding rate of 5 joints is 90.89%, which is because the composite solder is not rolled, the solder surface is uneven, and voids are easily generated during the welding process, resulting in a decrease in the joint bonding rate.

[0066] Comparative Example 6 Compared with Example 1, the only difference is that the step (3) is directly coated after rolling, and the step (3) is as follows: (3) The solder is coated on the surface of the alloy mesh, and the thickness of the composite solder after solidification is 0.105 mm. After cooling to room temperature, the composite solder is rolled to 0.1 mm by using a double roller sheeting machine.

[0067] The component analysis result shows that the component deviation is not more than 4%, which proves that the composite solder prepared by the present comparative example has good component uniformity. The tensile test result shows that the average tensile strength of 5 samples reaches 68.36 MPa, which is because the solder is directly coated on the alloy mesh, the solder cannot fully fill the mesh gap, and the solder and the mesh cannot fully metallurgical combine, thereby resulting in low solder strength. The composite solder prepared by the present comparative example is used to braze 10 mm x 10 mm surface modified aluminum alloy joints, and the average bonding rate of 5 joints is 90.55%, which shows that when the molten solder is coated on the substrate, the molten solder is difficult to penetrate into the deep pores of the skeleton due to the surface tension, and un-bonded cavities are easily generated, resulting in a decrease in the bonding rate.

[0068] The specific embodiments of the present application described above do not constitute a limitation on the scope of protection of the present application. Any various other corresponding changes and modifications made according to the technical concept of the present application shall be included in the scope of protection of the claims of the present application.

Claims

1. A gradient alloy skeleton reinforced composite solder, characterized by, The gradient alloy framework reinforced composite solder is composed of a composition gradient alloy framework with a core-shell structure and a solder, and the solder is filled in the composition gradient alloy framework with the core-shell structure. The composition gradient alloy framework with the core-shell structure comprises a metal framework and a Cu-Ni alloy coating layer.

2. The gradient alloy skeleton reinforced composite solder of claim 1, wherein, The metal framework is made of at least one of Ni, Cu, Fe, Cr, Ti and stainless steel, and the solder is at least one of Sn-based alloy, In-based alloy and Ga-based alloy.

3. A method of producing the gradient alloy skeleton reinforced composite solder according to any one of claims 1 to 2, characterized by, The method comprises the following steps: providing a metal mesh with a Cu and / or Ni metal layer on the surface; sintering the metal mesh with the Cu and / or Ni metal layer on the surface at high temperature to obtain an alloy mesh with a Cu-Ni alloy coating layer on the surface; filling the molten solder into the alloy mesh with the Cu-Ni alloy coating layer on the surface by an infiltration process, and then pressing to obtain the gradient alloy framework reinforced composite solder.

4. The method of claim 3, wherein the gradient alloy skeleton reinforced composite solder is prepared by the steps of: preparing a gradient alloy skeleton by mixing a plurality of alloy powders having different compositions; and mixing the gradient alloy skeleton and a solder powder to prepare a composite solder. In the metal mesh with the Cu and / or Ni metal layer on the surface, the weight percentage of the Cu and / or Ni metal layer is 5% to 90%.

5. The method of claim 3, wherein the gradient alloy skeleton reinforced composite solder is prepared by the steps of: preparing a gradient alloy skeleton by mixing a plurality of alloy powders having different compositions; and mixing the gradient alloy skeleton and a solder alloy powder to prepare a composite solder. The step of sintering the metal mesh with the Cu and / or Ni metal layer on the surface at high temperature comprises placing the metal mesh with the Cu and / or Ni metal layer on the surface between pressing plates and sintering at high temperature; wherein the pressing plates are plates on the surface of which the molten solder is poorly wetted; the number of the pressing plates is greater than or equal to 2.

6. The method of claim 3, wherein the gradient alloy skeleton reinforced composite solder is prepared by the steps of: preparing a gradient alloy solder by mixing a plurality of solder powders having different compositions; and mixing the gradient alloy solder with a reinforcing material. The temperature of the high-temperature sintering is 400-600°C, the time of the high-temperature sintering is 5-20 min, and the high-temperature sintering is carried out in a protective atmosphere.

7. The method of claim 3, wherein the gradient alloy skeleton reinforced composite solder is prepared by the steps of: preparing a gradient alloy solder by mixing a plurality of solder particles having different compositions; and mixing the gradient alloy solder with a reinforcing material. The infiltration process is at least one of pressure infiltration, vacuum infiltration, vacuum pressure infiltration and capillary infiltration.

8. The method of claim 3, wherein the gradient alloy skeleton reinforced composite solder is prepared by the steps of: preparing a gradient alloy skeleton by mixing a plurality of alloy particles having different compositions; and coating the gradient alloy skeleton with a solder material. The step of filling the molten solder into the alloy mesh with the Cu-Ni alloy coating layer on the surface by the infiltration process, and then pressing to obtain the gradient alloy framework reinforced composite solder comprises: placing the alloy mesh with the Cu-Ni alloy coating layer on the surface into a mold and immersing it into the molten solder, applying pressure to the mold to make the molten solder infiltrate into the grid gap, maintaining the pressure during the process of taking out the mold until the solder solidifies, and pressing after cooling to room temperature; wherein the thickness of the solidified composite solder is increased by 5-15 µm relative to the thickness of the alloy mesh with the Cu-Ni alloy coating layer on the surface.

9. The method of claim 3, wherein the gradient alloy skeleton reinforced composite solder is prepared by the steps of: preparing a gradient alloy solder by mixing a plurality of solder particles having different compositions; and mixing the gradient alloy solder with a reinforcing material having a higher melting point than the gradient alloy solder. After the pressing, the gradient alloy framework reinforced composite solder has a reduction ratio of 1% to 30%; wherein the reduction ratio is the ratio of the reduction amount to the initial thickness before the pressing.

10. Application of the gradient alloy framework reinforced composite solder according to any one of claims 1-2 in precision device connection.

Images