Copper-aluminum composite cellular board and preparation method thereof

Abstract

The invention belongs to the technical field of metal plate manufacturing, and discloses a copper-aluminum composite cellular board and a preparation method. The copper-aluminum composite honeycomb panel comprises a first aluminum alloy panel, a honeycomb core layer and a second pure copper panel which are sequentially stacked, wherein the honeycomb core layer is made of aluminum alloy; a first brazing layer is arranged between the honeycomb core layer and the first aluminum alloy panel; and a second brazing layer is arranged between the second pure copper panel and the honeycomb core layer. The prepared copper-aluminum composite cellular board has high peel strength and reliability, can meet the use requirements of attractiveness, practicability and economy at the same time, is simple and rapid in preparation method and has good economic value.

Description

Technical Field

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

[0002] The structure of a honeycomb panel generally includes upper and lower face panels and a honeycomb core layer sandwiched between the two face panels. The face panels are relatively thin and flat, while the honeycomb core layer is relatively thick and in the shape of an array module of multiple hexagonal hollow prisms. Due to the special three-dimensional structure of the honeycomb core layer, the honeycomb panel has the characteristics of light weight and strong compressive strength, and is widely used in fields such as building interior and exterior wall materials, airport, subway and high-speed railway station ceilings, rail transit interiors, aerospace, etc. In the related art, the aluminum honeycomb panels used are generally manufactured by the adhesive method. The strength and service life of the obtained aluminum honeycomb panels are restricted by the performance of the adhesive, and the adhesive is prone to aging and peeling 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 adhesive method, although the aluminum honeycomb panel obtained by the brazing method ensures the bonding strength between the plate and the honeycomb core material, oxidation or embrittlement is likely to occur at the brazing joints. Especially when bonding heterogeneous metal materials by the brazing method, the reliability will be further reduced. Summary of the Invention

[0003] The main object of the present invention is to develop a copper-aluminum composite honeycomb panel and a preparation method thereof, which can further improve the service life of the copper-aluminum composite honeycomb panel and the peel strength between the plates on the premise of simplifying the preparation process.

[0004] To achieve the above object, the present invention provides a copper-aluminum composite honeycomb panel, which includes a first aluminum alloy face panel, a honeycomb core layer, and a second copper face panel that are sequentially stacked. The material of the honeycomb core layer is aluminum alloy; a first brazing layer is provided between the honeycomb core layer and the first aluminum alloy face panel; a second brazing layer is provided between the second copper face panel and the honeycomb core layer.

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

[0006] In one embodiment, the preparation method of the modified polyimide resin includes the following steps: Add diamine monomers, catalysts and solvents into a reaction vessel and mix them. Then add dicarboxylic anhydride and carry out a prepolymerization reaction at 0 °C to 20 °C for 3 h to 5 h. After that, carry out an imidization reaction at 150 °C to 220 °C for 2 to 3 h to obtain a first mixed solution; add perfluoroalkyl acrylate and react at 80 °C to 100 °C for 2 h to 3 h to obtain a modified polyimide resin; wherein, the molar ratio of the diamine monomer to the dicarboxylic anhydride is (1.2 to 2):(0.8 to 1.5); the molar ratio of the perfluoroalkyl acrylate to the diamine monomer is (0.2 to 0.5):1.

[0007] 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.

[0008] In one embodiment, the second brazing layer is made of a second brazing paste, and the second brazing paste includes an alloy brazing filler metal, a brazing flux, and a binder in a weight ratio of (10 to 20):(12 to 16):(30 to 40); the second brazing filler metal includes: copper: 15 wt% to 30 wt%; nickel: 40 wt% to 55 wt%; aluminum: 30 wt to 40 wt%; Si: 3 wt% to 5 wt%; Mn: 0.5 wt% to 1.5 wt%; and inevitable impurities.

[0009] In one embodiment, a plating layer is further provided between the second brazing layer and the second copper panel; the preparation method of the plating layer includes the following steps: degrease, dry, and polish the brazing surface of the second copper panel, and then carry out electroless plating, controlling the temperature at 75 °C to 95 °C and the time at 3 h to 5 h; the solution used in the electroless plating process includes the following components: nickel sulfate 30 - 60 g / L, sodium hypophosphite 20 - 30 g / L, buffer 10 - 20 g / L, complexing agent 20 - 30 g / L, and the balance distilled water.

[0010] In one embodiment, the thickness of the honeycomb core layer is 10 mm to 100 mm.

[0011] In one embodiment, the thickness of the first brazing layer is 0.1 mm to 0.6 mm.

[0012] In one embodiment, the thickness of the second brazing layer is 0.1 mm to 0.4 mm.

[0013] 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.

[0014] 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.

[0015] The present invention also provides a method for preparing the copper-aluminum composite honeycomb panel, comprising the following steps: S1. Mix the raw materials at room temperature to prepare the first brazing paste and the second brazing paste respectively, and set aside; S2. Perform electroless plating on the second copper panel to form a coating; S3. Obtain the honeycomb core layer, coat the second brazing paste on the surface of the coating formed after the chemical plating treatment of the second copper panel, assemble the honeycomb core layer with the second copper panel, and perform the first brazing after the second brazing paste is adhesively fixed to obtain an intermediate; S4. Coat the first brazing paste on the brazing surface of the first aluminum alloy panel, assemble the intermediate obtained in step S3 and the first aluminum alloy panel, and perform the second brazing after the first brazing paste is adhesively fixed to obtain the copper-aluminum composite honeycomb panel.

[0016] In one embodiment, in step S2, during the first brazing process, vacuum brazing is used, the brazing temperature is 650°C to 750°C, and the brazing time is 60 min to 90 min.

[0017] In one embodiment, in step S4, during the second brazing process, vacuum brazing is used, the brazing temperature is 530°C to 600°C, and the brazing time is 40 min to 120 min.

[0018] In one embodiment, the temperature of the second brazing is lower than the temperature of the first brazing.

[0019] The technical solution in the present invention designs a copper-aluminum composite honeycomb panel, which tightly combines the copper plate, the aluminum honeycomb core layer and the aluminum plate by brazing. By using different brazing fillers, different brazing processes and step-by-step brazing methods, the copper plate, the honeycomb core layer are combined with the aluminum plate and the honeycomb core layer respectively; by using a binder with specific components and ratios in the brazing paste, it has good bonding and anti-displacement effects after assembly and curing, and the binder has good activation effects on the brazing filler during brazing, further promoting the bonding between metal plates; by setting a nickel-based coating between the copper plate and the aluminum honeycomb core layer, the formation of brittle intermetallic compounds is prevented, and the peel strength and reliability of the copper-aluminum composite honeycomb panel are further improved. The copper-aluminum composite honeycomb panel prepared by the present invention meets the requirements of beauty, practicality and economy, and the preparation process adopted is simple and fast, with good economic value. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0021] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0022] In addition, if there are descriptions such as "first" and "second" involved 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 implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, scenario B, or the scenario where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] The technical problem solved by this application is that in the related art, the aluminum honeycomb panels used generally adopt the gluing method for manufacturing. The strength and service life of the obtained aluminum honeycomb panels are restricted by the performance of the adhesive, and in extreme environments such as high temperature and high humidity, the adhesive is prone to aging and falling off, resulting in a significant reduction in the reliability of the honeycomb panel. Compared with the gluing method, although the aluminum honeycomb panel obtained by the brazing method ensures the bonding strength between the plate and the honeycomb core material, brazing is prone to oxidation or embrittlement. Especially when using the brazing method to bond heterogeneous metal materials, mutual diffusion occurs between the metals, accelerating catalysis, thereby significantly reducing the reliability.

[0024] In order to solve the above technical problems, a method based on powder extrusion printing for preparing pure copper workpieces is developed, which can significantly reduce the preparation cost of high-precision pure copper workpieces and improve the precision of the workpieces.

[0025] The present invention provides a copper-aluminum composite honeycomb panel, which comprises a first aluminum alloy panel, a honeycomb core layer, and a second copper panel that are stacked in sequence. The material of the honeycomb core layer is 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.

[0026] It should be noted that among the existing metal honeycomb panels, the metal honeycomb panel is usually an aluminum alloy honeycomb panel, that is, the materials of the honeycomb core layer and the panels on both sides thereof are made of the same kind of aluminum or aluminum alloy material. While providing excellent rigidity and stability, it can maintain a low weight. 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, due to requirements, the inventor of the present invention replaced one of the panels of the aluminum honeycomb panel with a copper plate. Correspondingly, a first brazing paste was designed for the brazing of 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 the brazing of 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 strengthening during the manufacturing process of the honeycomb panel.

[0027] In an embodiment, the first brazing layer is made from a first brazing paste, and the first brazing paste comprises an aluminum-based filler metal, a brazing flux, and a binder with a weight ratio of (15~25):(8~16):(30~40); the aluminum-based filler metal comprises: copper: 10wt%~15wt%; magnesium: 6wt%~11wt%; Si: 3wt%~5wt%; and aluminum and inevitable impurities; the brazing flux is KF-AlF3; the binder comprises the following raw materials in parts by weight: modified polyimide resin: 15 parts~30 parts; chromium sesquioxide micropowder: 1 part~3 parts; rosin resin: 12 parts~20 parts; organic solvent: 30 parts~50 parts.

[0028] It should be noted that the aluminum-based filler metal has aluminum as the main component and adds other alloy elements to adjust the melting point, strength, and wettability, and is a brazing material for welding aluminum and aluminum alloys. The brazing flux is a chemical material used to assist the filler metal in welding. Through its strong Lewis acidity, it is used to remove the oxide film on the surface of the base metal, promote the wetting and flow of the filler metal, and relieve the re-oxidation process during brazing.

[0029] It should also be noted that a modified polyimide resin is added to the binder. In the present invention, the modified polyimide resin is obtained by polymerizing a diamine monomer and a dicarboxylic anhydride under the action of a catalyst to obtain a polyimide resin, and then generating a modified polyimide resin under the action of a perfluoroalkyl acrylate. It has strong heat resistance and chemical stability. At the same time, the prepared modified polyimide resin has a fast curing speed and high strength after curing, which can ensure that the honeycomb core layer will not shift after being assembled and bonded with the copper plate or the aluminum plate, thus ensuring the dimensional accuracy of the prepared honeycomb panel.

[0030] On the one hand, active groups such as amino groups or carboxyl groups in the modified polyimide resin can graft with the hydroxyl groups on the surface of the filler metal, promoting the dispersion of the filler metal in the solder paste and improving the interfacial bonding force of the filler metal; on the other hand, after the modified polyimide resin and the rosin resin are mixed and grafted with the filler metal, the fluidity of the whole solder paste is improved, and it is easy to penetrate into the tiny pores of the board, thereby improving the strength of the solder layer.

[0031] In addition, adding chromium trioxide fine powder with a high melting point to the binder can promote the slow and uniform decomposition of the binder in the solder paste during soldering, and is also beneficial to preventing problems such as flowing of the solder paste due to excessive temperature in the initial stage of soldering; using chromium trioxide fine powder as a filler, when the solder paste is welded and cured on the surface of the board, the chromium trioxide fine powder will overflow on the surfaces of the first solder layer and the second solder layer, which can effectively inhibit the erosion of the metal in the solder layer by water and oxygen.

[0032] In a preferred embodiment, the particle size of the aluminum-based filler metal is 140 mesh to 220 mesh.

[0033] In a preferred embodiment, the particle size of the soldering flux is 170 mesh to 200 mesh.

[0034] In a preferred embodiment, the particle size of the chromium trioxide fine powder is 200 mesh to 280 mesh.

[0035] In an embodiment, the preparation method of the modified polyimide resin comprises the following steps: adding a diamine monomer, a catalyst and a solvent into a reaction vessel and mixing them, then adding a dicarboxylic anhydride and carrying out a prepolymerization reaction at 0°C to 20°C for 3h to 5h, and then carrying out an imidization reaction at 150°C to 220°C for 2 to 3h to obtain a first mixed solution; adding a perfluoroalkyl acrylate and reacting at 80°C to 100°C for 2h to 3h to obtain the modified polyimide resin; wherein, the molar ratio of the diamine monomer to the dicarboxylic anhydride is (1.2 to 2):(0.8 to 1.5); the molar ratio of the perfluoroalkyl acrylate to the diamine monomer is (0.2 to 0.5):1.

[0036] It should be noted that in the present invention, the diamine monomer reacts with the dicarboxylic anhydride to form a polyimide resin. Since the diamine monomer is in excess, the formed polyimide molecular chain has amino groups as active sites; under a heating state, the perfluoroalkyl acrylate can directly carry out an addition reaction with the polyimide molecular chain to graft the perfluoroalkyl group onto the polyimide molecular chain.

[0037] In a preferred embodiment, the perfluoroalkyl acrylate needs to be pretreated, including the following steps: Dissolve perfluoroalkyl acrylate in absolute ethanol, add 100 mL to 200 mL of NaOH solution with a concentration of 0.1 M to 5 M, stir and react at 80 °C for 1 h to 2 h, then add dilute hydrochloric acid until the pH is 3 to 4, and separate the organic layer to obtain the pretreated perfluoroalkyl acrylate.

[0038] It should be noted that the catalysts used in the prepolymerization reaction in this example include organotin compounds and organic ammonium compounds, such as dibutyltin dilaurate, trimethylamine, etc., and the dosage is about 0.1 wt% to 0.5 wt% of the monomer dosage; the catalysts used in the imidization reaction in this example include p-hydroxybenzoic acid, quinoline, acetic anhydride, and pyridine, etc., and the dosage is about 0.5 wt% to 2 wt% of the monomer dosage.

[0039] In a preferred embodiment, the diamine monomer is selected from any one of 1,6-hexanediamine, 1,4-butanediamine, 4,4'-diaminocyclohexylmethane, 1,3-cyclohexanedimethanamine, and m-phenylenediamine. It should be noted that by selecting the above diamine monomers with higher molecular chain flexibility, the rigidity of the synthesized polyimide can be significantly reduced. At the same time, by greatly shortening the imidization reaction time, the prepared polyimide resin is in a liquid state.

[0040] In a preferred embodiment, the perfluoroalkyl acrylate includes any one of perfluorooctyl acrylate and perfluorododecyl acrylate.

[0041] It should be noted that by using perfluorinated long-chain alkyl acrylate to modify the polyimide resin, the water resistance and antioxidant properties of the binder are enhanced. The first solder paste and the second solder paste prepared with this binder have a long storage time and are not prone to deterioration, can be prepared once and used for a long time, reducing the production and storage costs; moreover, the fluorine content of the modified polyimide is greatly increased, and the fluorides generated by decomposition during high-temperature soldering have high chemical activity, which together with the soldering flux is beneficial to promoting the removal of the oxide layer on the surface to be soldered of the substrate and the surface of the solder, thereby improving the soldering effect.

[0042] 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.

[0043] It should be noted that the molecular chains of the above dicarboxylic anhydrides also have relatively high flexibility, so that the prepared polyimide has relatively high fluidity; in addition, the polyimide resin synthesized using the above dicarboxylic anhydrides with a cyclic aliphatic structure has stronger anti-aging ability and stability, and the cured resin also has higher mechanical strength and higher thermal decomposition temperature.

[0044] In one embodiment, the second brazing layer is made of a second brazing paste, and the second brazing paste includes an alloy filler metal, a flux, and a binder with a weight ratio of (10 - 20):(12 - 16):(30 - 40); the second filler metal includes: copper: 15wt% - 30wt%; nickel: 40wt% - 55wt%; aluminum: 30wt - 40wt%; Si: 3wt% - 5wt%; Mn: 0.5wt% - 1.5wt%; and inevitable impurities.

[0045] It should be noted that the second brazing layer of the present invention is made of a second brazing paste, where the flux and the binder are the same as those of the first brazing paste, and the second brazing layer is adjusted according to the material of the surface to be brazed; the main components of the alloy filler metal in the second brazing paste are nickel and aluminum. The technical effects of using a nickel-plated layer and a second brazing layer mainly composed of nickel and aluminum to connect a copper plate and an aluminum alloy honeycomb core layer are as follows: First, the mutual diffusion rate between nickel and copper and aluminum is relatively slow, and the formed intermetallic compound is more stable, which will not significantly affect the peel strength between the plates; Second, the oxide film of nickel is denser, and the antioxidant ability after forming the brazing layer is stronger.

[0046] In one embodiment, a plating layer is further provided between the second brazing layer and the second copper panel; the preparation method of the plating layer includes the following steps: After degreasing, drying, and polishing the surface to be brazed of the second copper panel, electroless plating is carried out, controlling the temperature at 75°C - 95°C and the time at 3h - 5h; the solution used in the electroless plating process includes the following components: nickel sulfate 30 - 60g / L, sodium hypophosphite 20 - 30g / L, buffer 10 - 20g / L, complexing agent 20 - 30g / L, and the balance distilled water.

[0047] In a preferred embodiment, the thickness of the plating layer is 0.1mm - 0.3mm.

[0048] It should be noted that in this 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 / sodium hydrogen phosphate system; the complexing agent includes inorganic complexing agents and organic complexing agents. Inorganic complexing agents include sodium hexametaphosphate, sodium tripolyphosphate, etc., and organic complexing agents include sodium citrate, lactic acid, ethylenediaminetetraacetic acid, hydroxyethylidene diphosphonic acid, etc. In this embodiment, by using electroless plating to set a nickel-phosphorus plating layer between the second brazing layer and the second copper panel, the bonding property between the second copper panel and the second brazing layer can be significantly improved. It should be noted that during the electroless plating process, the phosphorus content in the plating layer needs to be controlled at 6wt% - 9wt%. Excessive phosphorus content will lead to an increase in the porosity of the plating layer, causing internal oxidation of the plating layer; too low phosphorus content will easily form an oxide layer on the surface of the plating layer, reducing the bonding strength between the plating layer and the brazing surface.

[0049] In one embodiment, in the copper-aluminum composite honeycomb panel, the thickness of the honeycomb core layer is 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.

[0050] In one embodiment, the thickness of the first brazing layer is 0.1 mm to 0.6 mm.

[0051] In one embodiment, the thickness of the second brazing layer is 0.1 mm to 0.4 mm.

[0052] 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.

[0053] 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.

[0054] The present invention also provides a method for preparing the copper-aluminum composite honeycomb panel, comprising the following steps: S1. Mix the raw materials at room temperature to prepare the first brazing paste and the second brazing paste respectively, and set aside; S2. Perform electroless plating on the second copper panel to form a coating; S3. Obtain the honeycomb core layer, coat the second brazing paste on the surface of the coating formed after the second copper panel is subjected to electroless plating, assemble the honeycomb core layer with the second copper panel, and perform the first brazing after the second brazing paste is bonded and fixed to obtain an intermediate; S4. Coat the first brazing paste on the brazing surface of the first aluminum alloy panel, assemble the intermediate obtained in step S3 and the first aluminum alloy panel, and perform the second brazing after the first brazing paste is bonded and fixed to obtain the copper-aluminum composite honeycomb panel.

[0055] It should be noted that in the present invention, by adopting a step-by-step brazing method, the copper plate, the honeycomb core layer, the aluminum plate, and the honeycomb core layer are respectively combined through the first brazing and the second brazing, 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.

[0056] 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.

[0057] In one embodiment, in the 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.

[0058] In one embodiment, the temperature of the second brazing is lower than that of the first brazing; and the temperature difference between the second brazing and the first brazing is not less than 160°C.

[0059] The present invention is further described below through specific embodiments: The present invention does not specifically limit the source of raw materials. The sources of raw materials in the embodiments of the present invention are as follows: The specific composition of the aluminum-based filler metal is as follows: Copper: 11.2 wt%; Magnesium: 7.7 wt%; Si: 3.5 wt%; and aluminum and inevitable impurities.

[0060] The specific composition of the alloy filler metal is as follows: Nickel: 42.1 wt%; Aluminum: 36.6 wt%; Copper: 16.3 wt%; Si: 3.8 wt%; Mn: 0.6 wt%; and inevitable impurities. Example 1

[0061] The copper-aluminum composite honeycomb panel in Example 1 includes a first aluminum alloy panel, a honeycomb core layer made of aluminum alloy, and a second copper panel which are sequentially laminated; 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.

[0062] Among them, the thickness of the honeycomb core layer is about 55 mm, the honeycomb core layer is made of an aluminum alloy foil with a thickness of about 0.15 mm, and the side length of the regular hexagonal honeycomb of the honeycomb core layer is about 6 mm; the first aluminum alloy panel uses an aluminum alloy plate with a thickness of about 2 mm, and the materials of the honeycomb core layer and the first aluminum alloy panel are both 6061 aluminum alloy; the second copper panel uses a T2 copper plate with a thickness of about 3 mm.

[0063] After cutting, a honeycomb core with a total size of 400 mm × 400 mm × 55 mm, a first aluminum alloy panel of 400 mm × 400 mm × 2 mm, and a second copper panel of 400 mm × 400 mm × 3 mm are obtained respectively.

[0064] The preparation method of the modified polyimide resin in Example 1 includes the following steps: Dissolve 255 g of 1,3 - cyclohexanedimethanamine and 1.4 g of dibutyltin dilaurate in 500 g of DMF solution. Control the temperature at 5 °C and slowly add 199 g of norbornane - 2,3 - dicarboxylic anhydride in total. React for 5 h while stirring. Then add 2.3 g of quinoline to the reaction system, raise the temperature to 160 °C, and react for 2 h to obtain the first mixed solution. In another reaction vessel, add 287 g of perfluorooctyl acrylate and 500 mL of absolute ethanol. Add 100 mL of a 0.5 M NaOH solution and stir and react at 80 °C for 2 h. Then dropwise add a 1 M hydrochloric acid solution until the pH is 3 - 4, separate and take the organic layer to obtain the pretreated product. Add the pretreated product to the first mixed solution and stir and react at 90 °C for 2 h to obtain the modified polyimide resin.

[0065] The preparation method of the binder in Example 1 includes the following steps: Mix 250 g of modified polyimide resin, 10 g of chromium sesquioxide fine powder, 150 g of rosin resin and 400 g of acetone solution, and stir at 80 °C for 10 min to obtain the binder. Among them, the particle size of the chromium sesquioxide fine powder is controlled to be 200 - 220 mesh.

[0066] The first soldering paste in Example 1 includes an aluminum - based filler metal, a flux and a binder with a weight ratio of 25:10:30. Mix the above raw materials evenly to obtain the first soldering paste.

[0067] The second soldering paste in Example 1 includes an alloy filler metal, a flux and a binder with a weight ratio of 20:14:30. Mix the above raw materials evenly to obtain the second soldering paste.

[0068] The preparation method of the copper - aluminum composite honeycomb panel in Example 1 includes the following steps: S1. At room temperature, mix the raw materials to obtain the first soldering paste and the second soldering paste respectively, and set aside; S2. Perform electroless plating treatment on the second copper panel. The solution formula used for electroless plating is: nickel sulfate 50 g / L, sodium hypophosphite 20 g / L, boric acid 16 g / L, EDTA 20 g / L and the balance of distilled water; control the reaction temperature at 80 °C and the reaction time at 3 h to form a coating with a thickness of about 0.1 mm; S3. Obtain the honeycomb core layer. Coat the second soldering paste on the coating of the second copper panel after electroless plating treatment, assemble it with one side of the honeycomb core layer, make the second soldering paste bond and fix the second copper panel and the honeycomb core layer, and then send it into a vacuum brazing furnace for brazing treatment at 720 °C for 60 min to form a second brazing layer with a thickness of about 0.3 mm to obtain the intermediate product; S4. Coat the brazing surface of the first aluminum alloy panel with the first brazing paste, assemble it with the other side of the honeycomb core layer of the intermediate body, so that the first brazing paste adhesively fixes the honeycomb core layer and the first aluminum alloy panel, and then send it into a vacuum brazing furnace for brazing treatment at 540 °C for 100 min to form a first brazing layer with a thickness of about 0.5 mm, thus obtaining a copper-aluminum composite honeycomb panel. Example 2

[0069] Example 2 is based on Example 1, and the differences are as follows: In Example 2, the first aluminum alloy panel uses an aluminum alloy plate with a thickness of about 3 mm, and the second copper panel uses a T2 copper plate with a thickness of about 2 mm; at the same time, the thickness of the second brazing layer is about 0.5 mm, and the thickness of the first brazing layer is about 0.3 mm. Example 3

[0070] Example 3 is based on Example 1, and the differences are as follows: In Example 3, the modified polyimide resin is not added to the binders in the first brazing paste and the second brazing paste. Example 4

[0071] Example 4 is based on Example 1, and the differences are as follows: In Example 4, the polyimide resin added to the binders in the first brazing paste and the second brazing paste is not subjected to modification treatment.

[0072] That is, the preparation method of the polyimide resin added to the binders in the first brazing paste and the second brazing paste in Example 4 includes the following steps: Dissolve 255 g of 1,3-cyclohexanediamine and 1.4 g of dibutyltin dilaurate in 500 g of DMF solution, control the temperature at 5 °C, slowly add a total of 199 g of norbornane-2,3-dicarboxylic anhydride, react for 5 h while stirring, then add 2.3 g of quinoline to the reaction system, raise the temperature to 160 °C, and react for 2 h to obtain a liquid polyimide resin. Comparative Example 1

[0073] Comparative Example 1 is based on Example 1, and the differences are as follows: In Comparative Example 1, it is a pure aluminum alloy honeycomb panel, and the parameters of the aluminum alloy panel and the honeycomb core layer are set with reference to Example 1. When brazing in Comparative Example 1, only the first brazing paste in Example 1 is used for welding.

[0074] Correspondingly, the preparation method of the aluminum alloy honeycomb panel in Comparative Example 1 includes the following steps: P1. Mix the raw materials at room temperature to obtain the first brazing paste for standby; P2. Obtain a honeycomb core layer and two aluminum alloy panels. Coat the first brazing paste on one side of each of the two aluminum alloy panels respectively, and assemble them with one side of the honeycomb core layer respectively, so that the brazing paste bonds and fixes the two aluminum alloy panels and the honeycomb core layer. Then send them into a vacuum brazing furnace and perform brazing treatment at 540 °C for 50 min to form a brazing layer with a thickness of about 0.5 mm, thus obtaining an aluminum alloy honeycomb panel. Comparative Example 2

[0075] Based on Example 1, the difference in Comparative Example 2 is that: in the preparation process of the copper-aluminum composite honeycomb panel in Comparative Example 2, in step S3, when performing the first brazing treatment, the brazing treatment is carried out at 650 °C for 60 min; and in step S4, when performing the second brazing treatment, the brazing treatment is carried out at 580 °C for 100 min. Comparative Example 3

[0076] Based on Example 1, the difference in Comparative Example 3 is that: only one brazing treatment is carried out in the preparation process of the copper-aluminum composite honeycomb panel in Comparative Example 3; Correspondingly, the preparation method of the copper-aluminum composite honeycomb panel in Comparative Example 3 includes the following steps: S1. Mix the raw materials at room temperature to prepare the first brazing paste and the second brazing paste respectively, and set aside; S2. Perform electroless plating on the second copper panel. The solution formula used for electroless plating is: nickel sulfate 50 g / L, sodium hypophosphite 20 g / L, boric acid 16 g / L, EDTA 20 g / L and the balance of distilled water; control the reaction temperature at 80 °C and the reaction time at 3 h to form a coating with a thickness of about 0.1 mm; S3. Obtain a honeycomb core layer. Coat the second brazing paste on the coating of the second copper panel after electroless plating treatment, and assemble it with one side of the honeycomb core layer, so that the second brazing paste bonds and fixes the second copper panel and the honeycomb core layer; coat the first brazing paste on the brazing surface to be brazed of the first aluminum alloy panel, and assemble it with the other side of the honeycomb core layer of the intermediate body, so that the first brazing paste bonds and fixes the honeycomb core layer and the first aluminum alloy panel. Then send them into a vacuum brazing furnace and perform brazing treatment at 600 °C for 60 min 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, thus obtaining a copper-aluminum composite honeycomb panel. Comparative Example 4

[0077] Based on Example 1, the difference is that: the preparation methods are different. The preparation method of the copper-aluminum composite honeycomb panel in Comparative Example 4 includes the following steps: S1. Mix the raw materials at room temperature to prepare the first brazing paste and the second brazing paste respectively, and set aside; S2. Coat the surface to be brazed of the first aluminum alloy panel with the first brazing paste, assemble it with one side of the honeycomb core layer, so that the first brazing paste bonds and fixes the honeycomb core layer and the first aluminum alloy panel, and then send it into a vacuum brazing furnace for brazing treatment at 540 °C for 100 min to form a first brazing layer with a thickness of about 0.5 mm, thus obtaining an intermediate product; S3. Conduct electroless plating on the second copper panel. The solution formula used for electroless plating is: nickel sulfate 50 g / L, sodium hypophosphite 20 g / L, boric acid 16 g / L, EDTA 20 g / L, and the balance is distilled water; control the reaction temperature at 80 °C and the reaction time at 3 h to form a coating with a thickness of about 0.1 mm; S4. Coat the coating of the second copper panel after electroless plating with the second brazing paste, assemble it with the other side of the honeycomb core layer of the intermediate product, so that the second brazing paste bonds and fixes the second copper panel and the honeycomb core layer, and then send it into a vacuum brazing furnace for brazing treatment at 720 °C for 60 min to form a second brazing layer with a thickness of about 0.3 mm, thus obtaining a copper-aluminum composite honeycomb panel.

[0078] Performance testing (1) Refer to the standard GB / T1457-2005 "Test Method for Drum Peel Strength of Sandwich Structures" to measure the drum peel performance (N·mm / mm) of the honeycomb panels obtained in Examples 1-4 and Comparative Examples 1-4 respectively.

[0079] (2) Refer to the standard GB / T1455-2005 "Test Method for Shear of Sandwich or Core Structures" to measure the shear strength (MPa) of the honeycomb panels obtained in Examples 1-4 and Comparative Examples 1-4 respectively.

[0080] The measurement results are shown in Table 1.

[0081] Table 1 Peeling strength (N·mm / mm) Shearing 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 The above are only exemplary embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the content of the specification of the present invention 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 includes a first aluminum alloy panel, a honeycomb core layer, and a second copper panel that are sequentially stacked, and the material of the honeycomb core layer is 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.

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

3. The copper-aluminum composite honeycomb panel according to claim 2, wherein The preparation method of the modified polyimide resin includes the following steps: Add diamine monomer, catalyst and solvent into a reaction vessel and mix, then add dicarboxylic anhydride and carry out a prepolymerization reaction at 0°C - 20°C for 3h - 5h, and then carry out an imidization reaction at 150°C - 220°C for 2 - 3h to obtain a first mixed solution; add perfluoroalkyl acrylate and react at 80°C - 100°C for 2h - 3h to obtain the modified polyimide resin; Among them, the molar ratio of the diamine monomer to the dicarboxylic anhydride is (1.2 - 2):(0.8 - 1.5); The molar ratio of the perfluoroalkyl acrylate to the diamine monomer is (0.2 - 0.5):

1.

4. The copper-aluminum composite honeycomb panel according to claim 3, 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.

5. The copper-aluminum composite honeycomb panel according to claim 2, wherein, The second brazing layer is prepared from a second brazing paste, and the second brazing paste includes an alloy filler metal, a brazing flux, and a binder with a weight ratio of (10 - 20):(12 - 16):(30 - 40); The second filler metal includes: copper: 15wt% - 30wt%; nickel: 40wt% - 55wt%; aluminum: 30wt - 40wt%; Si: 3wt% - 5wt%; Mn: 0.5wt% - 1.5wt%; and unavoidable impurities.

6. 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 preparation method of the plating layer includes the following steps: After degreasing, drying and polishing the brazing surface of the second copper panel, carry out electroless plating, control the temperature at 75°C - 95°C and the time at 3h - 5h; The solution used in the electroless plating process includes the following components: nickel sulfate 30 - 60g / L, sodium hypophosphite 20 - 30g / L, buffer 10 - 20g / L, complexing agent 20 - 30g / L, and the balance distilled water.

7. The copper-aluminum composite honeycomb panel according to claim 2, characterized in that, In the copper-aluminum composite honeycomb panel, The thickness of the honeycomb core layer is 10mm - 100mm; And / or, the thickness of the first brazing layer is 0.1mm - 0.6mm; 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.

8. A method for preparing the copper-aluminum composite honeycomb panel according to any one of claims 1 to 7, characterized in that, Comprising the following steps: S1. Mix the raw materials at room temperature to respectively prepare a first brazing paste and a second brazing paste, and set aside; S2. Perform electroless plating treatment on the second copper panel to form a coating; S3. Obtain the honeycomb core layer, coat the second brazing paste on the surface of the coating formed after the electroless plating treatment of the second copper panel, assemble the honeycomb core layer with the second copper panel, and perform the first brazing after the second brazing paste is bonded and fixed to obtain an intermediate; S4. Coat the first brazing paste on the brazing surface of the first aluminum alloy panel, assemble the intermediate obtained in step S3 and the first aluminum alloy panel, and perform the second brazing after the first brazing paste is bonded and fixed to obtain the copper-aluminum composite honeycomb panel.

9. The method for preparing a copper-aluminum composite honeycomb panel according to claim 8, wherein In step S2, during the first brazing process, vacuum brazing is used, 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 used, the brazing temperature is 530 °C to 600 °C, and the brazing time is 40 min to 120 min.

10. The preparation method of the copper-aluminum composite honeycomb board according to claim 8, characterized in that, The temperature of the second brazing is lower than the temperature of the first brazing.