Copper-aluminum composite honeycomb panel and preparation method

Abstract

The present invention belongs to the field of metal sheet manufacturing technology and discloses a copper-aluminum composite honeycomb panel and a method for preparing the panel. The copper-aluminum composite honeycomb panel comprises a first aluminum alloy panel, a honeycomb core layer, and a second pure copper panel, stacked in sequence. The honeycomb core layer is made of an aluminum alloy; a first brazing layer is provided between the honeycomb core layer and the first aluminum alloy panel; and a second brazing layer is provided between the second pure copper panel and the honeycomb core layer. The copper-aluminum composite honeycomb panel produced by the present invention has high peel strength and reliability, meeting the requirements of aesthetics, practicality, and economy. The production method is simple and quick, and has good economic value.

Description

Technical Field

[0001] The present invention relates to the technical field of metal plate manufacturing, and in particular to a copper-aluminum composite honeycomb panel and a preparation method thereof. Background Art

[0002] The structure of a honeycomb panel generally includes two layers of panels, an upper layer and an lower layer, and a honeycomb core layer sandwiched between the two layers of panels. The panels are thinner and flat, while the honeycomb core layer is thicker and in the shape of multiple hexagonal hollow prism array modules. Due to the special three-dimensional structure of the honeycomb core layer, the honeycomb panel has the characteristics of light weight and strong pressure resistance, and is widely used in building interior and exterior wall materials, ceilings of airports, subway and high-speed rail stations, rail transit interiors, aerospace and other fields. The aluminum honeycomb panels used in related technologies are generally manufactured by gluing. The strength and life of the obtained aluminum honeycomb panels are restricted by the performance of the adhesive, and the adhesive is prone to aging and falling off in extreme environments such as high temperature and high humidity, resulting in a significant reduction in the reliability of the honeycomb panel. Compared with the gluing method, the aluminum honeycomb panels made by the brazing method ensure the bonding strength between the panel and the honeycomb core material, but brazing is prone to oxidation or embrittlement. In particular, when brazing is used to bond heterogeneous metal materials, the reliability will be further reduced. Summary of the Invention

[0003] The main purpose of the present invention is to develop a copper-aluminum composite honeycomb panel and a preparation method thereof, so as to further improve the service life of the copper-aluminum composite honeycomb panel and the peeling strength between the panels while simplifying the preparation process.

[0004] To achieve the above-mentioned objectives, the present invention proposes a copper-aluminum composite honeycomb panel, which includes a first aluminum alloy panel, a honeycomb core layer, and a second copper panel stacked in sequence, wherein the honeycomb core layer is made of aluminum alloy; a first brazing layer is provided between the honeycomb core layer and the first aluminum alloy panel; and a second brazing layer is provided between the second copper panel and the honeycomb core layer.

[0005] In one embodiment, the first solder layer is made of a first solder paste, which includes an aluminum-based solder, a flux, and a binder in a weight ratio of (15~25): (8~16): (30~40); the aluminum-based solder includes: copper: 10wt%~15wt%; magnesium: 6wt%~11wt%; Si: 3wt%~5wt%; and aluminum and inevitable impurities; the flux is KF-AlF3; the binder includes the following raw materials in parts by weight: modified polyimide resin: 15 parts~30 parts; chromium trioxide fine powder: 1 part~3 parts; rosin resin: 12 parts~20 parts; and organic solvent: 30 parts~50 parts.

[0006] In one embodiment, the preparation method of the modified polyimide resin comprises the following steps:

[0007] A diamine monomer, a catalyst, and a solvent are added to a reaction container and mixed, followed by adding dicarboxylic anhydride and carrying out a prepolymerization reaction at 0°C to 20°C for 3h to 5h, followed by an imidization reaction at 150°C to 220°C for 2h to 3h to obtain a first mixed liquid; perfluoroalkyl acrylate is added and reacted at 80°C to 100°C for 2h to 3h to obtain a modified polyimide resin; wherein the molar ratio of the diamine monomer to the dicarboxylic anhydride is (1.2-2):(0.8-1.5); and the molar ratio of the perfluoroalkyl acrylate to the diamine monomer is (0.2-0.5):1.

[0008] In one embodiment, the dicarboxylic anhydride includes at least one of cyclopentane-1,2-dicarboxylic anhydride, cyclohexane-1,2-dicarboxylic anhydride, norbornane-2,3-dicarboxylic anhydride, and cyclooctatetraene-1,8-dicarboxylic anhydride.

[0009] In one embodiment, the second solder layer is made of a second solder paste, which includes an alloy solder, a flux and a binder in a weight ratio of (10~20): (12~16): (30~40); the alloy solder includes: copper: 15wt%~30wt%; nickel: 40wt%~55wt%; aluminum: 30wt%~40wt%; Si: 3wt%~5wt%; Mn: 0.5wt%~1.5wt%; and inevitable impurities.

[0010] In one embodiment, a plating layer is further provided between the second brazing layer and the second copper panel; a method for preparing the plating layer comprises the following steps: degreasing, drying, and polishing the surface of the second copper panel to be brazed, and then performing chemical plating at a controlled temperature of 75°C to 95°C for 3 hours to 5 hours; a solution used in the chemical plating process comprises the following components: 30-60 g / L nickel sulfate, 20-30 g / L sodium hypophosphite, 10-20 g / L buffer, 20-30 g / L chelating agent, and the remainder distilled water.

[0011] In one embodiment, the thickness of the honeycomb core layer is 10 mm to 100 mm.

[0012] In one embodiment, the thickness of the first solder layer is 0.1 mm to 0.6 mm.

[0013] In one embodiment, the thickness of the second solder layer is 0.1 mm to 0.4 mm.

[0014] In one embodiment, the material of the honeycomb core layer is selected from any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy.

[0015] In one embodiment, the material of the first aluminum alloy panel is selected from any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy.

[0016] The present invention also provides a method for preparing the copper-aluminum composite honeycomb panel, comprising the following steps:

[0017] S1. Mixing raw materials at room temperature to prepare a first soldering paste and a second soldering paste, respectively, for later use;

[0018] S2, performing chemical plating on the second copper panel to form a plating layer;

[0019] S3, obtaining a honeycomb core layer, coating the second brazing paste on the surface of the coating formed after the second copper panel is subjected to chemical plating, assembling the honeycomb core layer and the second copper panel, and performing a first brazing after the second brazing paste is bonded and fixed to obtain an intermediate;

[0020] S4. Apply the first brazing paste on the surface to be brazed of the first aluminum alloy panel, assemble the intermediate prepared in step S3 and the first aluminum alloy panel, and after the first brazing paste is bonded and fixed, perform a second brazing to obtain the copper-aluminum composite honeycomb panel.

[0021] In one embodiment, in step S3, during the first brazing process, vacuum brazing is adopted, the brazing temperature is 650° C. to 750° C., and the brazing time is 60 min to 90 min.

[0022] In one embodiment, in step S4, during the second brazing process, vacuum brazing is adopted, the brazing temperature is 530° C. to 600° C., and the brazing time is 40 min to 120 min.

[0023] In one embodiment, the temperature of the second brazing is lower than the temperature of the first brazing.

[0024] The technical solution of the present invention designs a copper-aluminum composite honeycomb panel, which tightly combines a copper plate, an aluminum honeycomb core layer, and an aluminum plate by brazing. The copper plate and honeycomb core layer are respectively combined with the aluminum plate and honeycomb core layer by using different brazing materials, different brazing processes, and a step-by-step brazing method. By using a binder with specific components and proportions in the brazing paste, it has good bonding and anti-shifting effects after assembly and curing. During brazing, the binder has a good activation effect on the brazing material, further promoting adhesion between the metal plates. By providing a nickel-based coating between the copper plate and the aluminum honeycomb core layer, the formation of brittle intermetallic compounds is prevented, further improving the peel strength and reliability of the copper-aluminum composite honeycomb panel. The copper-aluminum composite honeycomb panel produced by the present invention meets the requirements of aesthetics, practicality, and economy, and the preparation process adopted is simple and fast, with good economic value. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0027] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0028] The technical problem addressed by this application is that aluminum honeycomb panels commonly used in related technologies are manufactured using gluing methods. The strength and lifespan of the resulting panels are limited by the performance of the adhesive, and in extreme environments such as high temperature and high humidity, the adhesive is susceptible to aging and detachment, significantly reducing the panels' reliability. While brazing ensures the bond strength between the panels and the honeycomb core, brazing is susceptible to oxidation or embrittlement. In particular, when brazing is used to bond dissimilar metal materials, interdiffusion occurs between the metals, accelerating catalysis and significantly reducing reliability.

[0029] In order to solve the above technical problems, a powder extrusion printing method for preparing pure copper workpieces has been developed, which can significantly reduce the preparation cost of high-precision pure copper workpieces and improve the precision of the workpieces.

[0030] The present invention proposes a copper-aluminum composite honeycomb panel, which includes a first aluminum alloy panel, a honeycomb core layer and a second copper panel stacked in sequence, wherein the honeycomb core layer is made of aluminum alloy; a first brazing layer is provided between the honeycomb core layer and the first aluminum alloy panel; and a second brazing layer is provided between the second copper panel and the honeycomb core layer.

[0031] It should be noted that the metal honeycomb panels in existing metals are usually aluminum alloy honeycomb panels, that is, the materials of the honeycomb core layer and the panels on both sides are made of the same aluminum or aluminum alloy material, which can maintain a low weight while providing excellent rigidity and stability. At the same time, the aluminum alloy plate has the characteristics of easy processing and easy recycling, making it widely used in honeycomb panel materials. However, the inventors of the present invention replaced one of the panels of the aluminum honeycomb panel from an aluminum plate to a copper plate due to demand. Accordingly, a first brazing paste was designed for brazing the first aluminum alloy panel and the aluminum alloy honeycomb core layer to obtain a first brazing layer, and a second brazing paste was designed for brazing the second copper panel and the aluminum alloy honeycomb core layer to obtain a second brazing layer. The brazing paste plays a role in connecting and reinforcing the honeycomb panel during its manufacturing process.

[0032] In one embodiment, the first solder layer is made of a first solder paste, which includes an aluminum-based solder, a flux and a binder in a weight ratio of (15~25): (8~16): (30~40); the aluminum-based solder includes: copper: 10wt%~15wt%; magnesium: 6wt%~11wt%; Si: 3wt%~5wt%; and aluminum and inevitable impurities; the flux is KF-AlF3; the binder includes the following raw materials in parts by weight: modified polyimide resin: 15 parts~30 parts; chromium trioxide powder: 1 part~3 parts; rosin resin: 12 parts~20 parts; organic solvent: 30 parts~50 parts.

[0033] It should be noted that aluminum-based brazing filler metals are primarily composed of aluminum, with other alloying elements added to adjust their melting point, strength, and wettability. These filler metals are used for brazing aluminum and its alloys. Fluxes are chemical materials used to assist in brazing. Their strong Lewis acidity removes oxide films from the base metal surface, promotes brazing filler metal wetting and flow, and mitigates reoxidation during brazing.

[0034] It should also be noted that a modified polyimide resin is added to the binder. The modified polyimide resin in the present invention is obtained by a polymerization reaction of a diamine monomer and a dicarboxylic anhydride under the action of a catalyst to obtain a polyimide resin, which is then generated under the action of a perfluoroalkyl acrylate. The modified polyimide resin has strong temperature resistance and chemical stability. At the same time, the obtained modified polyimide resin has a fast curing speed and high strength after curing, which can ensure that the honeycomb core layer and the copper plate or aluminum plate will not shift after assembly and bonding, thereby ensuring the dimensional accuracy of the obtained honeycomb panel.

[0035] On the one hand, the active groups such as amino or carboxyl groups in the modified polyimide resin can be grafted with the hydroxyl groups on the surface of the solder, promoting the dispersion of the solder in the solder paste and improving the interfacial bonding strength of the solder; on the other hand, after the modified polyimide resin and rosin resin are mixed and grafted with the solder, the overall fluidity of the solder paste is improved, and it is easy to penetrate into the tiny pores of the plate, thereby improving the strength of the solder layer.

[0036] In addition, adding high-melting-point chromium oxide powder to the binder can promote the slow and uniform decomposition of the binder in the brazing paste during brazing, and is also beneficial to prevent the brazing paste from flowing due to excessively high temperature in the initial stage of brazing. When chromium oxide powder is used as a filler, the chromium oxide powder will overflow onto the surface of the first brazing layer and the second brazing layer when the brazing paste is welded to the surface of the plate and solidified, which can effectively inhibit the metal of the brazing layer from being corroded by water and oxygen.

[0037] In a preferred embodiment, the particle size of the aluminum-based solder is 140 mesh to 220 mesh.

[0038] In a preferred embodiment, the particle size of the flux is 170 mesh to 200 mesh.

[0039] In a preferred embodiment, the particle size of the chromium oxide powder is 200 mesh to 280 mesh.

[0040] In one embodiment, the preparation method of the modified polyimide resin includes the following steps: adding a diamine monomer, a catalyst, and a solvent into a reaction vessel and mixing them, then adding dicarboxylic anhydride and performing a prepolymerization reaction at 0°C to 20°C for 3h to 5h, then performing an imidization reaction at 150°C to 220°C for 2h to 3h to obtain a first mixed liquid; adding perfluoroalkyl acrylate and reacting at 80°C to 100°C for 2h to 3h to obtain a modified polyimide resin; wherein the molar ratio of the diamine monomer to the dicarboxylic anhydride is (1.2~2):(0.8~1.5); and the molar ratio of the perfluoroalkyl acrylate to the diamine monomer is (0.2~0.5):1.

[0041] It should be noted that in the present invention, the diamine monomer reacts with the dicarboxylic anhydride to form the polyimide resin. Due to the excess diamine monomer, the formed polyimide molecular chain has amino groups as active sites. Under heating conditions, the perfluoroalkyl acrylate can directly react with the polyimide molecular chain to graft the perfluoroalkyl group onto the polyimide molecular chain.

[0042] In a preferred embodiment, the perfluoroalkyl acrylate needs to be pretreated, comprising the following steps:

[0043] The perfluoroalkyl acrylate is dissolved in anhydrous ethanol, 100 mL to 200 mL of a 0.1 M to 5 M NaOH solution is added, and the mixture is stirred at 80° C. for 1 h to 2 h. Then, dilute hydrochloric acid is added dropwise to a pH of 3 to 4, and the organic layer is separated to obtain the pretreated perfluoroalkyl acrylate.

[0044] It should be noted that the catalysts used in the prepolymerization reaction in this embodiment include organic tin and organic ammonium, such as dibutyltin dilaurate, trimethylamine, etc., and the amount used is about 0.1wt%~0.5wt% of the monomer amount; the catalysts used in the imidization reaction in this embodiment include p-hydroxybenzoic acid, quinoline, acetic anhydride and pyridine, etc., and the amount used is about 0.5wt%~2wt% of the monomer amount.

[0045] In a preferred embodiment, the diamine monomer is selected from any one of 1,6-hexanediamine, 1,4-butanediamine, 4,4'-diaminocyclohexylmethane, 1,3-cyclohexanedimethyleneamine, and m-phenylenediamine. It should be noted that by selecting these diamine monomers with higher molecular chain flexibility, the rigidity of the synthesized polyimide can be significantly reduced. Simultaneously, by significantly shortening the imidization reaction time, the resulting polyimide resin is rendered liquid.

[0046] In a preferred embodiment, the perfluoroalkyl acrylate includes any one of perfluorooctyl acrylate and perfluorododecyl acrylate.

[0047] It should be noted that by modifying the polyimide resin with perfluoro long-chain alkyl acrylate, the water resistance and oxidation resistance of the binder are enhanced. The first solder paste and the second solder paste prepared using the binder have a long storage time and are not easy to deteriorate. They can be prepared once and then used for a long time, reducing production and storage costs; and the fluorine content of the modified polyimide is greatly increased. The fluoride produced by decomposition during high-temperature brazing has high chemical activity, and the interaction with the brazing flux is beneficial to promoting the removal of the oxide layer on the surface of the substrate to be brazed and the surface of the brazing material, thereby improving the brazing effect.

[0048] In a preferred embodiment, the dicarboxylic anhydride includes at least one of cyclopentane-1,2-dicarboxylic anhydride, cyclohexane-1,2-dicarboxylic anhydride, norbornane-2,3-dicarboxylic anhydride, and cyclooctatetraene-1,8-dicarboxylic anhydride.

[0049] It should be noted that the molecular chain of the above-mentioned dicarboxylic anhydride is also highly flexible, thereby making the obtained polyimide have higher fluidity; in addition, the polyimide resin synthesized using the above-mentioned dicarboxylic anhydride with a cyclic aliphatic structure has stronger aging resistance and stability, and the cured resin also has higher mechanical strength and higher thermal decomposition temperature resistance.

[0050] In one embodiment, the second solder layer is made of a second solder paste, which includes an alloy solder, a flux and a binder in a weight ratio of (10~20): (12~16): (30~40); the alloy solder includes: copper: 15wt%~30wt%; nickel: 40wt%~55wt%; aluminum: 30wt%~40wt%; Si: 3wt%~5wt%; Mn: 0.5wt%~1.5wt%; and inevitable impurities.

[0051] It should be noted that the second brazing layer of the present invention is made of a second brazing paste, in which the brazing agent and adhesive are the same as those of the first brazing paste, and the second brazing layer is adjusted in combination with the material of the surface to be brazed; the main components of the alloy brazing material in the second brazing paste are nickel and aluminum, and the technical effects of using a nickel-plated layer and a second brazing layer with nickel and aluminum as the main components to connect the copper plate and the aluminum alloy honeycomb core layer are: first, the mutual diffusion rate of nickel with copper and aluminum is slow, and the intermetallic compounds formed are more stable, which will not significantly affect the peel strength between the plates; second, the nickel oxide film is denser, and the antioxidant ability after the brazing layer is formed is stronger.

[0052] In one embodiment, a plating layer is further provided between the second brazing layer and the second copper panel; a method for preparing the plating layer comprises the following steps: degreasing, drying, and polishing the surface of the second copper panel to be brazed, and then performing chemical plating at a controlled temperature of 75°C to 95°C for 3 hours to 5 hours; a solution used in the chemical plating process comprises the following components: 30-60 g / L nickel sulfate, 20-30 g / L sodium hypophosphite, 10-20 g / L buffer, 20-30 g / L chelating agent, and the remainder distilled water.

[0053] In a preferred embodiment, the thickness of the coating is 0.1 mm to 0.3 mm.

[0054] It should be noted that, in the present embodiment, the buffer is used to form a weak acid environment, including boric acid / sodium borate system, acetic acid / sodium acetate system, citric acid / sodium citrate system, sodium dihydrogen phosphate / disodium hydrogen phosphate system; the complexing agent includes an inorganic complexing agent and an organic complexing agent, the inorganic complexing agent includes sodium hexametaphosphate, sodium tripolyphosphate, etc., and the organic complexing agent includes sodium citrate, lactic acid, ethylenediaminetetraacetic acid, hydroxyethyl diphosphonic acid, etc. In the present embodiment, a nickel-phosphorus coating is provided between the second brazing layer and the second copper panel by chemical plating, which can significantly improve the bonding of the second copper panel and the second brazing layer. It should be noted that the phosphorus content in the coating needs to be controlled to be 6wt% ~ 9wt% during the chemical plating process. Too high a phosphorus content will lead to an increase in the porosity of the coating and induce oxidation inside the coating; too low a phosphorus content will easily form an oxide layer on the surface of the coating, which will reduce the bonding strength between the coating and the brazing surface.

[0055] In one embodiment, in the copper-aluminum composite honeycomb panel, the honeycomb core layer has a thickness of 10 mm to 100 mm. In one embodiment, the honeycomb core layer is made of aluminum alloy foil, and the thickness of the aluminum alloy foil used to prepare the honeycomb core layer is about 0.05 mm to 0.2 mm.

[0056] In one embodiment, the thickness of the first solder layer is 0.1 mm to 0.6 mm.

[0057] In one embodiment, the thickness of the second solder layer is 0.1 mm to 0.4 mm.

[0058] In one embodiment, the material of the honeycomb core layer is selected from any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy.

[0059] In one embodiment, the material of the first aluminum alloy panel is selected from any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy.

[0060] The present invention also provides a method for preparing the copper-aluminum composite honeycomb panel, comprising the following steps:

[0061] S1. Mixing raw materials at room temperature to prepare a first soldering paste and a second soldering paste, respectively, for later use;

[0062] S2, performing chemical plating on the second copper panel to form a plating layer;

[0063] S3, obtaining a honeycomb core layer, coating the second brazing paste on the surface of the coating formed after the second copper panel is subjected to chemical plating, assembling the honeycomb core layer and the second copper panel, and performing a first brazing after the second brazing paste is bonded and fixed to obtain an intermediate;

[0064] S4. Apply the first brazing paste on the surface to be brazed of the first aluminum alloy panel, assemble the intermediate prepared in step S3 and the first aluminum alloy panel, and after the first brazing paste is bonded and fixed, perform a second brazing to obtain the copper-aluminum composite honeycomb panel.

[0065] It should be noted that in the present invention, the copper plate and the honeycomb core layer are respectively combined with the aluminum plate and the honeycomb core layer by the first brazing and the second brazing respectively by adopting a step-by-step brazing method, and the second brazing layer with a higher brazing temperature is brazed first, so that both the first brazing layer and the second brazing layer have better brazing effects.

[0066] In one embodiment, in step S3, during the first brazing process, vacuum brazing is adopted, the brazing temperature is 650° C. to 750° C., and the brazing time is 60 min to 90 min.

[0067] In one embodiment, in step S4, during the second brazing process, vacuum brazing is adopted, the brazing temperature is 530° C. to 600° C., and the brazing time is 40 min to 120 min.

[0068] In one embodiment, the temperature of the second brazing is lower than the temperature of the first brazing; and the temperature difference between the second brazing and the first brazing is not less than 160°C.

[0069] The present invention is further described below by means of specific examples:

[0070] The present invention does not impose any specific restrictions on the sources of raw materials. The sources of raw materials in the embodiments of the present invention are as follows:

[0071] The specific ratio of aluminum-based brazing filler metal is as follows:

[0072] Copper: 11.2wt%; Magnesium: 7.7wt%; Si: 3.5wt%; and aluminum and inevitable impurities.

[0073] The specific ratio of alloy solder is as follows:

[0074] Nickel: 42.1wt%; Aluminum: 36.6wt%; Copper: 16.3wt%; Si: 3.8wt%; Mn: 0.6wt%; and inevitable impurities. Example 1

[0075] The copper-aluminum composite honeycomb panel in Example 1 includes a first aluminum alloy panel, an aluminum alloy honeycomb core layer and a second copper panel stacked in sequence; a first brazing layer is provided between the honeycomb core layer and the first aluminum alloy panel; and a second brazing layer is provided between the second copper panel and the honeycomb core layer.

[0076] Among them, the thickness of the honeycomb core layer is about 55mm, the honeycomb core layer is made of aluminum alloy foil with a thickness of about 0.15mm, and the side length of the regular hexagonal honeycomb of the honeycomb core layer is about 6mm; the first aluminum alloy panel adopts an aluminum alloy plate with a thickness of about 2mm, and the material of the honeycomb core layer and the first aluminum alloy panel are both 6061 aluminum alloy; the second copper panel adopts T2 copper plate with a thickness of about 3mm.

[0077] After cutting, a honeycomb core with a total size of 400 mm × 400 mm × 55 mm, a first aluminum alloy panel with a size of 400 mm × 400 mm × 2 mm, and a second copper panel with a size of 400 mm × 400 mm × 3 mm were obtained.

[0078] The preparation method of the modified polyimide resin in Example 1 comprises the following steps:

[0079] 255 g of 1,3-cyclohexanedimethylamine and 1.4 g of dibutyltin dilaurate were dissolved in 500 g of DMF solution, the temperature was controlled at 5° C., and a total of 199 g of norbornane-2,3-dicarboxylic anhydride was slowly added, and the mixture was stirred and reacted for 5 hours. Then, 2.3 g of quinoline was added to the reaction system, the temperature was raised to 160° C., and the mixture was reacted for 2 hours to obtain a first mixed solution. In another reaction container, 287 g of perfluorooctyl acrylate and 500 mL of anhydrous ethanol were added, and 100 mL of a 0.5 M NaOH solution was added. The mixture was stirred and reacted at 80° C. for 2 hours. Then, a 1 M hydrochloric acid solution was added dropwise until the pH was 3-4, and the organic layer was separated to obtain a pretreated product. The pretreated product was added to the first mixed solution, and the mixture was stirred and reacted at 90° C. for 2 hours to obtain a modified polyimide resin.

[0080] The preparation method of the binder in Example 1 comprises the following steps:

[0081] 250 g of modified polyimide resin, 10 g of chromium oxide powder, 150 g of rosin resin, and 400 g of acetone solution were mixed and stirred at 80° C. for 10 minutes to prepare an adhesive. The particle size of the chromium oxide powder was controlled to be 200-220 mesh.

[0082] The first solder paste in Example 1 includes aluminum-based solder, brazing agent, and adhesive in a weight ratio of 25:10:30. The first solder paste is prepared by uniformly mixing the above raw materials.

[0083] The second solder paste in Example 1 includes an alloy solder, a brazing agent, and a binder in a weight ratio of 20:14:30. The second solder paste is prepared by uniformly mixing the above raw materials.

[0084] The method for preparing the copper-aluminum composite honeycomb panel in Example 1 comprises the following steps:

[0085] S1. Mixing raw materials at room temperature to prepare a first soldering paste and a second soldering paste, respectively, for later use;

[0086] S2. Electroless plating is performed on the second copper panel, wherein the solution formula used for electroless plating is: 50 g / L nickel sulfate, 20 g / L sodium hypophosphite, 16 g / L boric acid, 20 g / L EDTA, and the balance distilled water; the reaction temperature is controlled at 80° C. and the reaction time is 3 hours to form a coating with a thickness of about 0.1 mm;

[0087] S3. Obtain a honeycomb core layer, apply a second brazing paste to the coating of the second copper panel after chemical plating, assemble it with one side of the honeycomb core layer, and bond and fix the second copper panel and the honeycomb core layer with the second brazing paste. Then, place the honeycomb core layer in a vacuum brazing furnace and braze at 720° C. for 60 minutes to form a second brazing layer with a thickness of approximately 0.3 mm, thereby obtaining an intermediate.

[0088] S4. Apply a first brazing paste on the surface to be brazed of the first aluminum alloy panel, assemble it with the other side of the honeycomb core layer of the intermediate, so that the first brazing paste adheres and fixes the honeycomb core layer and the first aluminum alloy panel, and then put it into a vacuum brazing furnace and braze it at 540°C for 100 minutes to form a first brazing layer with a thickness of about 0.5 mm, thereby obtaining a copper-aluminum composite honeycomb panel. Example 2

[0089] Example 2 is based on Example 1, with the following differences: in Example 2, the first aluminum alloy panel adopts an aluminum alloy plate with a thickness of approximately 3 mm, and the second copper panel adopts a T2 copper plate with a thickness of approximately 2 mm; at the same time, the thickness of the second brazing layer is approximately 0.5 mm, and the thickness of the first brazing layer is approximately 0.3 mm. Example 3

[0090] Example 3 is based on Example 1, with the difference being that modified polyimide resin is not added to the binder in the first solder paste and the second solder paste in Example 3. Example 4

[0091] Example 4 is based on Example 1, with the difference that the polyimide resin added to the binder in the first solder paste and the second solder paste in Example 4 is not modified.

[0092] That is, the preparation method of the polyimide resin added to the binder in the first solder paste and the second solder paste in Example 4 includes the following steps: dissolving 255g of 1,3-cyclohexanedimethylamine and 1.4g of dibutyltin dilaurate in 500g of DMF solution, controlling the temperature to 5°C, slowly adding a total of 199g of norbornane-2,3-dicarboxylic anhydride, and reacting while stirring for 5h, then adding 2.3g of quinoline to the reaction system, raising the temperature to 160°C, and reacting for 2h to obtain a liquid polyimide resin. Comparative Example 1

[0093] Comparative Example 1 is based on Example 1, with the following differences: Comparative Example 1 is a pure aluminum alloy honeycomb panel, wherein the parameters of the aluminum alloy panel and the honeycomb core layer are set with reference to Example 1, and when brazing is performed in Comparative Example 1, only the first brazing paste in Example 1 is used for welding.

[0094] Accordingly, the preparation method of the aluminum alloy honeycomb panel in Comparative Example 1 includes the following steps:

[0095] P1. Mix the raw materials at room temperature to prepare a first solder paste for later use;

[0096] P2. Obtain a honeycomb core layer and two aluminum alloy panels, apply a first brazing paste on one side of each of the two aluminum alloy panels, and assemble them with one side of the honeycomb core layer respectively, so that the second brazing paste bonds and fixes the two aluminum alloy panels and the honeycomb core layer. Then, put them into a vacuum brazing furnace and braze them at 540°C for 50 minutes to form a brazing layer with a thickness of about 0.5 mm, thereby obtaining an aluminum alloy honeycomb panel. Comparative Example 2

[0097] Comparative Example 2 is based on Example 1, except that: during the preparation process of the copper-aluminum composite honeycomb panel in Comparative Example 2, in step S3, the first brazing treatment is performed at 650°C for 60 minutes; and in step S4, the second brazing treatment is performed at 580°C for 100 minutes. Comparative Example 3

[0098] Comparative Example 3 is based on Example 1, except that: the copper-aluminum composite honeycomb panel in Comparative Example 3 is brazed only once during the preparation process;

[0099] Accordingly, the preparation method of the copper-aluminum composite honeycomb panel in Comparative Example 3 includes the following steps:

[0100] S1. Mixing raw materials at room temperature to prepare a first soldering paste and a second soldering paste, respectively, for later use;

[0101] S2. Electroless plating is performed on the second copper panel, wherein the solution formula used for electroless plating is: 50 g / L nickel sulfate, 20 g / L sodium hypophosphite, 16 g / L boric acid, 20 g / L EDTA, and the balance distilled water; the reaction temperature is controlled at 80° C. and the reaction time is 3 hours to form a coating with a thickness of about 0.1 mm;

[0102] S3. Obtain a honeycomb core layer, apply a second brazing paste on the coating of the second copper panel after chemical plating, assemble it with one side of the honeycomb core layer, and make the second brazing paste bond and fix the second copper panel and the honeycomb core layer; apply a first brazing paste on the surface to be brazed of the first aluminum alloy panel, assemble it with the other side of the honeycomb core layer of the intermediate, and make the first brazing paste bond and fix the honeycomb core layer and the first aluminum alloy panel, and then put it into a vacuum brazing furnace, and braze it at 600°C for 60 minutes to form a second brazing layer with a thickness of about 0.3 mm and a first brazing layer with a thickness of about 0.5 mm, thereby obtaining a copper-aluminum composite honeycomb panel. Comparative Example 4

[0103] Comparative Example 4 is based on Example 1, except that the preparation method is different. The preparation method of the copper-aluminum composite honeycomb panel in Comparative Example 4 includes the following steps:

[0104] S1. Mixing raw materials at room temperature to prepare a first soldering paste and a second soldering paste, respectively, for later use;

[0105] S2. Coating a first brazing paste on the surface to be brazed of the first aluminum alloy panel, assembling it with one side of the honeycomb core layer, allowing the first brazing paste to bond and fix the honeycomb core layer and the first aluminum alloy panel. Then, placing the panel in a vacuum brazing furnace, brazing the panel at 540° C. for 100 minutes to form a first brazing layer with a thickness of approximately 0.5 mm, thereby producing an intermediate.

[0106] S3. Electroless plating is performed on the second copper panel, wherein the solution formula used for electroless plating is: 50 g / L nickel sulfate, 20 g / L sodium hypophosphite, 16 g / L boric acid, 20 g / L EDTA, and the balance distilled water; the reaction temperature is controlled to 80° C., the reaction time is 3 hours, and a coating thickness of about 0.1 mm is formed;

[0107] S4. Coat the second copper panel after chemical plating with a second brazing paste, assemble it with the other side of the honeycomb core layer of the intermediate, and make the second brazing paste bond and fix the second copper panel and the honeycomb core layer. Then, put them into a vacuum brazing furnace and braze them at 720° C. for 60 minutes to form a second brazing layer with a thickness of about 0.3 mm, thereby producing a copper-aluminum composite honeycomb panel.

[0108] Performance testing

[0109] (1) The roller peeling properties (N·mm / mm) of the honeycomb panels prepared in Examples 1-4 and Comparative Examples 1-4 were measured with reference to the standard GB / T1457-2005 “Test method for roller peeling strength of sandwich structures”.

[0110] (2) The shear strength (MPa) of the honeycomb panels prepared in Examples 1-4 and Comparative Examples 1-4 was measured with reference to the standard GB / T1455-2005 “Shear test method for sandwich or core structures”.

[0111] The measurement results are shown in Table 1.

[0112] Table 1

[0113] Peel strength (N·mm / mm) Shear strength (MPa) Example 1 266.5 11.9 Example 2 264.8 11.9 Example 3 252.9 10.7 Example 4 254.5 11.1 Comparative Example 1 241.5 8.5 Comparative Example 2 248.4 10.5 Comparative Example 3 245.2 9.8 Comparative Example 4 246.1 9.6

[0114] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention specification under the technical concept of the present invention, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A copper-aluminum composite honeycomb panel, characterized in that: The copper-aluminum composite honeycomb panel comprises a first aluminum alloy panel, a honeycomb core layer, and a second copper panel stacked in sequence, wherein the honeycomb core layer is made of aluminum alloy; A first brazing layer is provided between the honeycomb core layer and the first aluminum alloy panel; a second brazing layer is provided between the second copper panel and the honeycomb core layer; The first brazing layer is made of a first brazing paste, which includes an aluminum-based brazing filler metal, a brazing flux, and a binder; The binder includes a modified polyimide resin, and the preparation method of the modified polyimide resin includes the following steps: A diamine monomer, a catalyst, and a solvent are added to a reaction container and mixed, followed by adding dicarboxylic anhydride and carrying out a prepolymerization reaction at 0°C to 20°C for 3h to 5h, followed by an imidization reaction at 150°C to 220°C for 2h to 3h to obtain a first mixed solution; perfluoroalkyl acrylate is added and reacted at 80°C to 100°C for 2h to 3h to obtain a modified polyimide resin; wherein the molar ratio of the diamine monomer to the dicarboxylic anhydride is (1.2-2):(0.8-1.5); and the molar ratio of the perfluoroalkyl acrylate to the diamine monomer is (0.2-0.5):

1.

2. The copper-aluminum composite honeycomb panel according to claim 1, wherein: The first solder layer is made of a first solder paste, which includes an aluminum-based solder, a solder flux, and a binder in a weight ratio of (15-25): (8-16): (30-40); The aluminum-based brazing filler metal comprises: copper: 10wt%~15wt%; magnesium: 6wt%~11wt%; Si: 3wt%~5wt%; and aluminum and inevitable impurities; the brazing flux is KF-AlF3; The adhesive comprises the following raw materials in parts by weight: modified polyimide resin: 15 parts to 30 parts; Chromium trioxide powder: 1 to 3 parts; rosin resin: 12 to 20 parts; organic solvent: 30 to 50 parts.

3. The copper-aluminum composite honeycomb panel according to claim 1, wherein: The dicarboxylic anhydride includes at least one of cyclopentane-1,2-dicarboxylic anhydride, cyclohexane-1,2-dicarboxylic anhydride, norbornane-2,3-dicarboxylic anhydride, and cyclooctatetraene-1,8-dicarboxylic anhydride.

4. The copper-aluminum composite honeycomb panel according to claim 1, wherein: The second soldering layer is made of a second soldering paste, which includes an alloy solder, a solder flux and a binder in a weight ratio of (10-20): (12-16): (30-40); The alloy solder comprises: copper: 15wt%~30wt%; nickel: 40wt%~55wt%; aluminum: 30wt%~40wt%; Si: 3wt%~5wt%; Mn: 0.5wt%~1.5wt%; and inevitable impurities.

5. The copper-aluminum composite honeycomb panel according to claim 1, wherein: A plating layer is further provided between the second brazing layer and the second copper panel; The method for preparing the coating comprises the following steps: After degreasing, drying and polishing the surface to be brazed of the second copper panel, chemical plating is performed at a controlled temperature of 75° C. to 95° C. for 3 h to 5 h. The solution used in the chemical plating process includes the following components: 30-60 g / L of nickel sulfate, 20-30 g / L of sodium hypophosphite, 10-20 g / L of a buffer, 20-30 g / L of a complexing agent, and the balance of distilled water.

6. The copper-aluminum composite honeycomb panel according to claim 1, characterized in that: In the copper-aluminum composite honeycomb panel, The thickness of the honeycomb core layer is 10 mm to 100 mm; And / or, the thickness of the first brazing layer is 0.1 mm to 0.6 mm; And / or, the thickness of the second brazing layer is 0.1 mm to 0.4 mm; And / or, the material of the honeycomb core layer is selected from any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy; And / or, the material of the first aluminum alloy panel is selected from any one of 3003 aluminum alloy, 6061 aluminum alloy, and 6063 aluminum alloy.

7. A method for preparing the copper-aluminum composite honeycomb panel according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Mixing raw materials at room temperature to prepare a first soldering paste and a second soldering paste, respectively, for later use; S2, performing chemical plating on the second copper panel to form a plating layer; S3, obtaining a honeycomb core layer, coating the second brazing paste on the surface of the coating formed after the second copper panel is subjected to chemical plating, assembling the honeycomb core layer and the second copper panel, and performing a first brazing after the second brazing paste is bonded and fixed to obtain an intermediate; S4. Apply the first brazing paste on the surface to be brazed of the first aluminum alloy panel, assemble the intermediate prepared in step S3 and the first aluminum alloy panel, and after the first brazing paste is bonded and fixed, perform a second brazing to obtain the copper-aluminum composite honeycomb panel.

8. The method for preparing the copper-aluminum composite honeycomb panel according to claim 7, wherein: In step S3, during the first brazing process, vacuum brazing is adopted, the brazing temperature is 650° C. to 750° C., and the brazing time is 60 min to 90 min; And / or, in step S4, during the second brazing process, vacuum brazing is adopted, the brazing temperature is 530° C. to 600° C., and the brazing time is 40 min to 120 min.

9. The method for preparing the copper-aluminum composite honeycomb panel according to claim 7, wherein: The temperature of the second brazing is lower than the temperature of the first brazing.