Aluminum-based composite material and preparation method therefor, and electronic device

Abstract

The present application belongs to the field of electrical materials. Disclosed are an aluminum-based composite material and a preparation method therefor, and an electronic device. The preparation method comprises: purifying an aluminum-based base material, so as to obtain a purified aluminum-based base material; forming a metal protective layer on the surface of the purified aluminum-based base material, so as to obtain a first composite material intermediate; subjecting the first composite material intermediate to a first electroplating treatment, so as to corrode the metal protective layer and form a first metal coating on the surface of the aluminum-based base material, thereby obtaining a second composite material intermediate; and subjecting the second composite material intermediate to a second electroplating treatment, so as to form a second metal coating on the surface of the first metal coating, thereby obtaining an aluminum-based composite material. The preparation method can improve the compactness and flatness of the coating, does not require the introduction of other inert noble metals during the preparation process, and also has the advantages of a short operation process, convenience, high efficiency, high reliability, low costs, etc.

Description

Aluminum-based composite material, preparation method thereof, and electronic device

[0001] This application claims priority to Chinese patent application No. 202311021148.9 filed on August 11, 2023, entitled “Aluminum-based composite materials, preparation methods thereof, and electronic devices,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to the field of electrical materials, and in particular to aluminum-based composite materials, preparation methods thereof, and electronic devices. Background Art

[0003] Aluminum-based materials have advantages such as high thermal conductivity, adjustable thermal expansion coefficient, low density, strong dimensional stability, and excellent electrical properties, making them widely used in the manufacture of printed circuit boards and circuit packaging structures. To enhance the solderability of aluminum-based materials and improve their physical and chemical properties (such as reducing porosity and enhancing corrosion resistance), electroless nickel immersion gold (ENIG) is currently commonly used to form nickel and gold coatings on the aluminum-based material surface.

[0004] Electroless nickel-gold (ENG) currently suffers from the following issues: the electroless nickel layer easily dissolves and corrodes the electroless gold layer, resulting in "black pad syndrome" and reducing the surface wettability of the electroless gold layer, making it impossible to form electrical interconnect structures through bonding processes. Related technologies have either improved the corrosion resistance of the nickel layer by doping it with heteroatoms such as P and Cu, or by placing an inert Pd layer between the nickel and gold layers.

[0005] However, the chemical plating layer prepared by the related technology has poor flatness and density, which makes the corrosion resistance and oxidation resistance of the coating not stable in the long term.

[0006] Public content

[0007] In view of this, the present disclosure provides an aluminum-based composite material and a preparation method thereof, and an electronic device, which can solve the technical problems in the related art.

[0008] In one aspect, a method for preparing an aluminum-based composite material is provided, the method comprising:

[0009] Purifying the aluminum-based substrate to obtain a purified aluminum-based substrate;

[0010] forming a metal protective layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate;

[0011] performing a first electroplating treatment on the first composite material intermediate so that the metal protective layer is corroded to form a first metal plating layer on the surface of the aluminum-based substrate, thereby obtaining a second composite material intermediate;

[0012] The second composite material intermediate is subjected to a second electroplating treatment, so that a second metal coating is formed on the surface of the first metal coating, thereby obtaining the aluminum-based composite material.

[0013] The preparation method of the aluminum-based composite material provided by the embodiment of the present disclosure forms a metal protective layer on the surface of the aluminum-based substrate. The metal protective layer can protect the aluminum-based substrate from forming an oxide film on its surface. When the first electroplating treatment is performed, the metal protective layer can be corroded as a sacrificial layer, and the first metal coating replaces the metal protective layer and adheres to the surface of the aluminum-based substrate, which not only helps to improve the bonding strength between the first metal coating and the aluminum-based substrate, but also can prevent the aluminum-based substrate from being oxidized and corroded by the electroplating solution during the electroplating process. Because the aluminum-based substrate is relatively active, it is very easy to be corroded in the electroplating solution, and the provision of the metal protective layer effectively solves this problem. Furthermore, the second composite material intermediate having the first metal coating is subjected to a second electroplating treatment, so that the second metal coating is formed on the surface of the first metal coating to obtain an aluminum-based composite material. In the aluminum-based composite material, the aluminum-based substrate, the first metal coating, and the second metal coating are stacked in sequence, and the first metal coating and the second metal coating are formed by an electroplating process, which not only makes the first metal coating and the second metal coating uniform and dense, so as to avoid element diffusion between the two, which is beneficial to improving the stability of the coating, but also makes the surface of the first metal coating and the second metal coating smooth. In summary, the preparation method of the aluminum-based composite material provided by the embodiment of the present disclosure can not only improve the density and flatness of the coating, thereby improving the corrosion resistance and oxidation resistance of the coating, but also does not require the introduction of other inert precious metals during the preparation process, and also has the advantages of a short, convenient, efficient, reliable, and low-cost operation process.

[0014] In some possible implementations, the metal protective layer includes a zinc layer. The zinc layer can not only effectively protect the aluminum-based substrate, but also has a simple and reliable preparation process and will not damage the aluminum-based substrate.

[0015] In some possible implementations, forming a metal protective layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate includes:

[0016] placing the purified aluminum-based substrate in a zinc plating solution for zinc plating, forming a zinc layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate;

[0017] The zinc plating solution comprises the following components:

[0018] 50g / L-200g / L of sodium hydroxide, 5g / L-50g / L of potassium sodium tartrate, 1g / L-10g / L of zinc oxide, 0.2g / L-2g / L of iron and ferrous compounds, and water as the balance so that the pH value of the zinc plating solution is 12-14.

[0019] Electroless plating of zinc on the surface of an aluminum substrate is simple and easy, and the thickness of the zinc layer can be controlled. Using the zinc plating solution to treat the aluminum substrate removes and suppresses the Al2O3 film, exposing the aluminum substrate's surface to an ideal pre-plating state. This allows the first metal coating to grow on the aluminum substrate after the zinc layer is sacrificed.

[0020] In some possible implementations, the thickness of the metal protection layer is 1 nm-100 nm.

[0021] In some possible implementations, the first metal plating layer includes a nickel plating layer or a nickel-phosphorus alloy plating layer;

[0022] The second metal plating layer includes a gold plating layer.

[0023] In this way, an aluminum-based composite material with a nickel-plated layer and a gold-plated layer can be prepared. The nickel-plated layer and the gold-plated layer are formed by an electroplating process, so that the two are uniform, dense and flat. The dense nickel-plated layer and the gold-plated layer avoid the mutual diffusion of nickel and gold elements, and both are pure phases without any other miscellaneous elements, thereby avoiding the Galvani effect and eliminating the black pad problem. This not only improves the stability of the nickel-plated layer and the gold-plated layer, making their corrosion resistance and oxidation resistance more stable, but also the surface flatness and uniform texture of the coating are conducive to welding and gold wire bonding.

[0024] In some possible implementations, the first metal coating is a nickel coating, and the first electroplating treatment utilizes a nickel plating solution comprising the following components in the following proportions: 1g / L-50g / L nickel sulfate, 1g / L-50g / L nickel chloride, 1g / L-50g / L nickel methanesulfonate, 1g / L-50g / L hydrochloric acid, 1g / L-10g / L primary brightener, 0.1g / L-1g / L auxiliary brightener, and the balance being water. A nickel plating solution employing this formulation has the advantages of stable chemical properties and a long lifespan.

[0025] In some possible implementations, during the first electroplating process, the current density is 0.1ASD-5ASD, and the electroplating temperature is 45° C.-65° C. By defining the electroplating nickel operating parameters as above, it has the advantages of increasing the plating rate and making the coating thickness uniform.

[0026] In some possible implementations, the second metal coating is a gold coating, and the second electroplating treatment utilizes a gold plating solution comprising the following components in the following ratios: 10-20 g / L gold trichloride, 50-130 g / L sodium sulfite, 30-50 g / L ethylenediaminetetraacetic acid, 30-50 g / L citric acid, 50-80 g / L potassium chloride, and the balance being water. The gold plating solution employing this formulation has the advantages of increasing the plating rate and achieving a uniform coating thickness.

[0027] In some possible implementations, during the second electroplating process, the current density is 0.1ASD-5ASD, and the electroplating temperature is 30° C.-45° C. By limiting the electroplating parameters as above, it has the advantages of increasing the plating rate and making the plated film thickness uniform.

[0028] In some possible implementations, the method for preparing the aluminum-based composite material further includes: before the purified aluminum-based substrate is subjected to galvanizing, performing a surface etching treatment on the purified aluminum-based substrate, so that a rough structure is formed on the surface of the purified aluminum-based substrate;

[0029] The rough structure is used to enhance the bonding force between the aluminum-based substrate and the first metal coating.

[0030] In some possible implementations, the surface etching treatment is performed by placing the cleaned aluminum-based substrate in an etching solution;

[0031] The etching solution comprises the following components:

[0032] 10g / L-50g / L tetramethylammonium hydroxide, 10g / L-50g / L disodium ethylenediaminetetraacetic acid, 5g / L-20g / L zinc oxide, 5g / L-20g / L barbituric acid, 0.1g / L-1g / L soluble silver salt, and water as the balance so that the pH value of the etching solution is 10-13.

[0033] In another aspect, an aluminum-based composite material is provided, comprising an aluminum-based substrate, a first metal coating, and a second metal coating arranged in sequence;

[0034] The unit cell diameter of the first metal coating is less than or equal to 100 nm;

[0035] The unit cell diameter of the second metal coating layer is less than or equal to 100 nm.

[0036] In some possible implementations, a surface of the aluminum-based substrate that is combined with the first metal coating has a rough structure, and the rough structure is used to enhance the bonding force between the aluminum-based substrate and the first metal coating.

[0037] On the other hand, an electronic device is provided, comprising a device body and a pad structure connected to the device body, wherein the pad structure is prepared using any of the above-mentioned aluminum-based composite materials.

[0038] The aluminum-based composite material provided by the embodiments of the present disclosure has a unit cell diameter of the nickel plating layer less than or equal to 100 nm, and the lattice in the nickel plating layer is dense, making the nickel plating layer uniform and dense. The unit cell diameter of the gold plating layer is less than or equal to 100 nm, and the lattice in the gold plating layer is dense, making the gold plating layer uniform and dense, and having an excellent covering effect on the nickel plating layer. The dense nickel plating layer and the gold plating layer avoid the mutual diffusion of nickel and gold elements, thereby avoiding the Galvani effect and the black pad problem. This not only improves the stability of the nickel plating layer and the gold plating layer, making their corrosion resistance and oxidation resistance more stable, but also the gold plating layer with a smooth surface and uniform texture is also conducive to welding and gold wire bonding.

[0039] In some possible implementations, the electronic device includes: a chip and a printed circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a flow chart of a preparation process of an exemplary aluminum-based composite material provided by an embodiment of the present disclosure;

[0041] FIG2 is a flow chart of another exemplary preparation of an aluminum-based composite material provided in an embodiment of the present disclosure;

[0042] FIG3 is a SEM image of the nickel coating of the aluminum-based composite material provided in Example 1 at different magnifications;

[0043] FIG4 is a SEM image of the nickel coating of the aluminum-based composite material provided in Comparative Example 1 at different magnifications;

[0044] FIG5 is a SEM image of the gold-plated layer of the aluminum-based composite material provided in Example 1 at different magnifications;

[0045] FIG6 is a SEM image of the gold-plated layer of the aluminum-based composite material provided in Comparative Example 1 at different magnifications. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present disclosure in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0047] At present, chemical nickel gold is also known as chemical nickel-plated gold. A nickel coating and a gold coating are formed on the surface of an aluminum-based material in sequence by chemical plating. However, the grains of the nickel coating and the gold coating formed by chemical plating are relatively loose, which makes it easy for nickel and gold elements to diffuse with each other, and then the two undergo electrochemical reactions to produce "black pad syndrome". It can be seen that the stability of the nickel coating and the gold coating is poor, and this also makes the coating surface uneven and uneven, and the surface wettability of the gold coating decreases. Not only can solder paste and the like not be naturally spread on it, which is not conducive to welding, but the gold wire cannot be electrically interconnected with the gold coating surface through the bonding process.

[0048] In order to solve the technical problems existing in the related art, the present disclosure provides a method for preparing an aluminum-based composite material. As shown in FIG1 , the method for preparing the aluminum-based composite material includes:

[0049] Step S11: purify the aluminum-based substrate to obtain a purified aluminum-based substrate.

[0050] Step S12: forming a metal protective layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate.

[0051] Step S13: performing a first electroplating treatment on the first composite material intermediate, so that the metal protective layer is corroded to form a first metal plating layer on the surface of the aluminum-based substrate, thereby obtaining a second composite material intermediate.

[0052] Step S14: performing a second electroplating treatment on the second composite material intermediate, so that a second metal coating is formed on the surface of the first metal coating, thereby obtaining an aluminum-based composite material.

[0053] The preparation method of the aluminum-based composite material provided by the embodiment of the present disclosure forms a metal protective layer on the surface of the aluminum-based substrate. The metal protective layer can protect the aluminum-based substrate from forming an oxide film on its surface. When the first electroplating treatment is performed, the metal protective layer can be corroded as a sacrificial layer, and the first metal coating replaces the metal protective layer and adheres to the surface of the aluminum-based substrate, which not only helps to improve the bonding strength between the first metal coating and the aluminum-based substrate, but also can prevent the aluminum-based substrate from being oxidized and corroded by the electroplating solution during the electroplating process. Because the aluminum-based substrate is relatively active, it is very easy to be corroded in the electroplating solution, and the provision of the metal protective layer effectively solves this problem. Furthermore, the second composite material intermediate having the first metal coating is subjected to a second electroplating treatment, so that the second metal coating is formed on the surface of the first metal coating to obtain an aluminum-based composite material. In this aluminum-based composite material, the aluminum-based substrate, the first metal coating, and the second metal coating are stacked in sequence. The first metal coating and the second metal coating are formed using an electroplating process. This not only makes the first metal coating and the second metal coating uniform and dense, thereby avoiding element diffusion between the two and improving the stability of the coating, but also makes the surfaces of the first metal coating and the second metal coating smooth.

[0054] In summary, the preparation method of the aluminum-based composite material provided in the embodiment of the present disclosure can not only improve the density and flatness of the coating, thereby improving the corrosion resistance and oxidation resistance of the coating, but also does not require the introduction of other inert precious metals during the preparation process. It also has the advantages of a short, convenient, efficient, reliable and low-cost operation process.

[0055] In some examples, the first metal plating layer includes a nickel plating layer or a nickel-phosphorus alloy plating layer; the second metal plating layer includes a gold plating layer. For example, the first metal plating layer is a nickel plating layer, and the second metal plating layer is a gold plating layer, thereby achieving a combination of the aluminum-based substrate with the nickel and gold to obtain an electroplated Ni-Au structure. In this way, the formed aluminum-based composite material includes the aluminum-based substrate, the nickel plating layer, and the gold plating layer stacked in sequence, making it suitable for use in a pad structure.

[0056] As can be seen, in the method for preparing the aluminum-based composite material provided by the embodiments of the present disclosure, during the first electroplating process, the metal protective layer can be etched away as a sacrificial layer, and a dense and smooth nickel plating layer can be attached to the surface of the aluminum-based substrate in place of the metal protective layer. Electroplating gold is then performed on the second composite material intermediate having the nickel plating layer, so that a dense and smooth gold plating layer is further formed on the surface of the dense and smooth nickel plating layer, thereby obtaining the aluminum-based composite material.

[0057] In this aluminum-based composite material, the nickel plating layer and the gold plating layer are formed using an electroplating process, making them uniform, dense and flat. The dense nickel plating layer and the gold plating layer avoid mutual diffusion of nickel and gold elements, and both are pure phases without any other miscellaneous elements, thereby avoiding the Galvani effect and eliminating the black pad problem. This not only improves the stability of the nickel plating layer and the gold plating layer, making their corrosion resistance and oxidation resistance more stable, but also the surface flatness and uniform texture of the plating layer are conducive to welding and gold wire bonding.

[0058] The following is a more detailed description of each step involved in the aluminum-based composite material and its function.

[0059] In step S11, the aluminum-based substrate is purified to obtain a purified aluminum-based substrate to ensure that impurities on the surface of the aluminum-based substrate are removed. The impurities include inorganic impurities and organic impurities, and the organic impurities include oily substances.

[0060] In some examples, the aluminum-based substrate is purified, including: placing the aluminum-based substrate in a decontamination solution, soaking it at 40°C-70°C for 3min-10min, using the decontamination solution to decompose organic impurities such as grease and dirt on the aluminum-based substrate, and separating them from the surface of the aluminum-based substrate along with inorganic impurities and entering the decontamination solution.

[0061] Illustratively, the soaking temperature during purification treatment includes but is not limited to: 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, etc., and the soaking time includes but is not limited to: 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min, etc.

[0062] In some examples, the impurity removal solution includes the following components in the following proportions: 3g / L-30g / L sodium hydroxide, 5g / L-50g / L carbonate, 5g / L-20g / L phosphate, 1g / L-20g / L boron compound, 1g / L-10g / L surfactant, and water as the balance so that the pH value of the impurity removal solution is 8-10.

[0063] The concentration of sodium hydroxide includes but is not limited to: 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, etc.

[0064] The carbonate can be at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. The concentration of the carbonate includes but is not limited to: 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, etc.

[0065] The phosphate can be at least one of sodium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, potassium monohydrogen phosphate, and potassium dihydrogen phosphate. The concentration of the phosphate includes but is not limited to: 5g / L, 10g / L, 12g / L, 15g / L, 18g / L, 20g / L, etc.

[0066] The boron compound can be at least one of dimethylamine borane, trimethylammonium borane, diethylammonium borane, triethylammonium borane, and dicyclohexylammonium borane. The concentration of the boron compound includes but is not limited to: 5 g / L, 10 g / L, 12 g / L, 15 g / L, 18 g / L, 20 g / L, etc.

[0067] The surfactant can be an anionic surfactant or a nonionic surfactant, for example, at least one of alkylphenol polyoxyethylene ether and polyoxyethylene alkylolamide. The concentration of the surfactant includes but is not limited to: 1g / L, 2g / L, 3g / L, 4g / L, 5g / L, 6g / L, 7g / L, 8g / L, 9g / L, 10g / L, etc.

[0068] In the embodiment of the present disclosure, the material of the aluminum-based substrate can be pure aluminum or an aluminum alloy. Examples of some aluminum alloys include but are not limited to the following: Al-Si alloy (Si content is 0.5wt%-1wt%), Al-Cu alloy (Cu content is 0.5wt%-1wt%), Al-Si-Cu alloy (Si and Cu are in any proportion, but the total content of the two is less than or equal to 1wt%).

[0069] In step S12, a metal protective layer is formed on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate. It can be seen that the first composite material intermediate includes the aluminum-based substrate and the metal protective layer located on the surface of the aluminum-based substrate.

[0070] In some examples, the metal protective layer can cover all surfaces of the aluminum-based substrate to achieve all-round protection of the aluminum-based substrate. Of course, the metal protective layer can also be arranged on only one surface of the aluminum-based substrate.

[0071] Under the premise of not damaging the aluminum-based substrate, the metal protective layer can be formed on the surface of the aluminum-based substrate in various ways, for example, chemical plating and the like.

[0072] In the embodiments of the present disclosure, metals that can serve as sacrificial layers during nickel electroplating without damaging the aluminum-based substrate can be used to prepare metal protective layers. For example, the metal protective layer includes but is not limited to a zinc layer. The zinc layer can not only effectively protect the aluminum-based substrate, but also its preparation process is relatively simple and reliable and will not cause damage to the aluminum-based substrate.

[0073] When the metal protective layer is a zinc layer, the embodiment of the present disclosure forms a metal protective layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate, including: placing the purified aluminum-based substrate in a zinc plating solution for zinc plating, forming a zinc layer on the surface of the purified aluminum-based substrate, and obtaining a first composite material intermediate.

[0074] The zinc layer is plated on the surface of the aluminum-based substrate by chemical plating. The operation is simple and the thickness of the zinc layer can be controlled. For example, the thickness of the zinc layer can be adjusted by adjusting at least one of the following parameters: the concentration of zinc oxide in the zinc plating solution and the time of the zinc plating treatment.

[0075] In some examples, the zinc plating solution includes the following components in the following proportions: 50 g / L-200 g / L of sodium hydroxide, 5 g / L-50 g / L of potassium sodium tartrate, 1 g / L-10 g / L of zinc oxide, 0.2 g / L-2 g / L of iron and ferrous compounds, and water as the balance such that the pH value of the zinc plating solution is 12-14.

[0076] The concentration of sodium hydroxide includes but is not limited to: 50g / L, 60g / L, 70g / L, 80g / L, 90g / L, 100g / L, 110g / L, 120g / L, 130g / L, 140g / L, 150g / L, 160g / L, 170g / L, 180g / L, 190g / L, 200g / L, etc.

[0077] The concentration of potassium sodium tartrate includes but is not limited to: 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, etc.

[0078] The concentration of zinc oxide includes but is not limited to: 1g / L, 2g / L, 3g / L, 4g / L, 5g / L, 6g / L, 7g / L, 8g / L, 9g / L, 10g / L, etc.

[0079] The iron compound may be at least one of ferric chloride, ferric sulfate, ferric nitrate, and ferrocene, and the ferrous compound may be at least one of ferrous sulfate and ferrous gluconate. The concentration of the iron compound or ferrous compound includes, but is not limited to, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.7 g / L, 1.8 g / L, 1.9 g / L, 2 g / L, and the like.

[0080] The zinc plating solution is an alkaline solution, and zinc oxide ZnO dissolves in the alkaline solution to form Zn(OH)4 2-, so that the aluminum-based substrate undergoes the following replacement reaction in the above-mentioned zinc plating solution:

[0081] Al+Zn(OH)4 2- →AlO 2- +Zn+H2O+OH - +1 / 2H2, it can be seen that during the galvanizing process, the Al2O3 film is removed and contained, and the Zn element is replaced, so that a zinc layer is formed on the surface of the aluminum-based substrate to prevent the regeneration of the Al2O3 film on the aluminum-based substrate.

[0082] By using the above-mentioned zinc plating solution to treat the aluminum-based substrate, the Al2O3 film can be removed and contained, thereby exposing the aluminum-based surface of the aluminum-based substrate and making it present an ideal surface state before plating. In this way, after the zinc layer is sacrificed, the surface of the aluminum-based substrate can grow the first metal plating layer.

[0083] In some examples, the temperature of the galvanizing treatment is 20°C-30°C, and the time of the galvanizing treatment is 5s-20s. For example, the temperature of the galvanizing treatment includes but is not limited to: 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, etc., and the time of the galvanizing treatment includes but is not limited to: 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, 20s, etc.

[0084] By setting the operating parameters of the galvanizing treatment within the above ranges, there are advantages in that the surface of the aluminum-based substrate can be leveled and the formation of an oxide film can be prevented.

[0085] In some examples, the purified aluminum-based substrate is placed in a zinc plating solution for zinc plating to form a zinc layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate, including:

[0086] The purified aluminum-based substrate is placed in a zinc plating solution for a first zinc plating treatment, and a zinc layer to be removed is formed on the surface of the purified aluminum-based substrate.

[0087] The aluminum-based substrate with the zinc layer to be removed on the surface is pickled to remove the zinc layer to obtain the aluminum-based substrate with a bare surface.

[0088] The aluminum-based substrate with the exposed surface is subjected to a second zinc plating treatment to form a target zinc layer on the exposed surface of the aluminum-based substrate to obtain a first composite material intermediate.

[0089] The first zinc layer formed is stripped and removed by acid, which helps to make the exposed surface of the aluminum-based substrate present a better plating state, and further the exposed surface of the aluminum-based substrate is zinc-plated again, thereby obtaining a zinc layer with a stronger activation effect, a denser and smoother surface.

[0090] For example, the first galvanizing treatment is performed at a temperature of 20° C. to 30° C. for a time of 8 to 20 seconds. The second galvanizing treatment is performed at a temperature of 20° C. to 30° C. for a time of 5 to 20 seconds.

[0091] For example, the pickling is performed using a nitric acid solution with a mass concentration of 20% to 40%, for example, a nitric acid solution with a mass concentration of 30%. The pickling temperature can be 20° C. to 30° C., including but not limited to 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C., 30° C., etc. The pickling time can be 1 second to 5 seconds, including but not limited to 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, etc.

[0092] In some examples, the thickness of the metal protective layer, such as the zinc layer, is 1 nm-100 nm, and further, the thickness is 1 nm-50 nm, which includes but is not limited to 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc.

[0093] The metal protective layer may be continuous or discontinuous. For example, when the thickness of the metal protective layer is less than 20 nm, the metal protective layer may be discontinuous and distributed in dispersed islands.

[0094] In step S13 , the first composite material intermediate is subjected to a first electroplating treatment, so that the metal protective layer is corroded, thereby forming a first metal plating layer on the surface of the aluminum-based substrate, thereby obtaining a second composite material intermediate.

[0095] Exemplarily, the first metal coating is a nickel coating, and the first electroplating treatment uses a nickel plating solution. During the nickel electroplating process, the nickel plating solution corrodes the metal protective layer, such as the zinc layer, and the formed nickel coating is formed on the surface of the exposed aluminum-based substrate. Since the nickel coating obtained by electroplating has fine grain growth, a dense and uniform nickel coating is obtained by electroplating on the surface of the aluminum-based substrate, which can effectively resist oxidation and corrosion.

[0096] In some examples, the nickel plating solution provided by the embodiments of the present disclosure includes components in the following proportions: 1g / L-50g / L of nickel sulfate, 1g / L-50g / L of nickel chloride, 1g / L-50g / L of nickel methanesulfonate, 1g / L-50g / L of hydrochloric acid, 1g / L-10g / L of main brightener, 0.1g / L-1g / L of auxiliary brightener, and the balance is water.

[0097] The nickel plating solution of the above formula has the advantages of stable chemical properties, long service life, stable and controllable nickel plating process, dense and smooth nickel plating layer, etc. The mass concentration of hydrochloric acid can be 30%-40%, for example, hydrochloric acid with a mass concentration of 36% is used.

[0098] The concentration of nickel sulfate includes but is not limited to: 2g / L, 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, etc.

[0099] The concentration of nickel chloride includes but is not limited to: 1g / L, 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, etc.

[0100] The concentration of nickel methanesulfonate includes but is not limited to: 2 g / L, 6 g / L, 10 g / L, 17 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, etc.

[0101] The concentration of hydrochloric acid includes but is not limited to: 2g / L, 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, etc.

[0102] The concentration of the main brightener includes but is not limited to: 1g / L, 2g / L, 3g / L, 4g / L, 5g / L, 6g / L, 7g / L, 8g / L, 9g / L, 10g / L, etc.

[0103] The main brightener includes but is not limited to: at least one of sodium o-sulfonylbenzamide, diphenylsulfinic acid, coumarin (oxazinone), 1,4-butynediol, pyridine propanesulfonic acid inner salt, N,N-diethylpropargylamine, and ethoxylated propargyl alcohol.

[0104] The concentration of the auxiliary brightener includes but is not limited to: 0.2g / L, 0.3g / L, 0.4g / L, 0.5g / L, 0.6g / L, 0.7g / L, 0.8g / L, 0.9g / L, 1g / L, etc.

[0105] The auxiliary brightener includes, but is not limited to, at least one of sodium ethylene sulfonate, sodium styrene sulfonate, sodium allyl sulfonate, allyl sulfonamide, and sodium propyne sulfonate.

[0106] In some examples, during the first electroplating process, the current density is 0.1ASD-5ASD, and the electroplating temperature is 45° C.-65° C. By limiting the electroplating nickel operating parameters as described above, it has the advantages of increasing the plating rate, making the plated film thickness uniform, and making the film layer dense and smooth.

[0107] According to tests, the plating rate of the embodiment of the present disclosure during nickel plating can reach 1.5 μm / min, compared with the plating rate of chemical plating of 0.15 μm / min, which shortens the process time of the embodiment of the present disclosure by 5 to 10 times.

[0108] Illustratively, the current density includes, but is not limited to, 0.5ASD, 1ASD, 1.1ASD, 1.2ASD, 1.3ASD, 1.4ASD, 1.5ASD, 1.6ASD, 1.7ASD, 1.8ASD, 1.9ASD, 2ASD, 2.1ASD, 2.2ASD, 2.3ASD, 2.4ASD, 2.5ASD, 2.6ASD, 2.7ASD, 2.8ASD, 2.9ASD, 3ASD, 3.1ASD, 3.2ASD, 3.3ASD, 3.4ASD, 3.5ASD, 4ASD, 4.5ASD, 5ASD, and the like.

[0109] Electroplating temperatures include but are not limited to: 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, etc.

[0110] In some examples, the nickel plating time may be 1 minute to 5 minutes, and the thickness of the nickel plating layer may be controlled by controlling at least one of the current density and the plating time. For example, the thickness of the nickel plating layer may be 0.5 μm to 5 μm.

[0111] The nickel coating is 99.9% pure nickel with no impurities and is capable of completely covering the aluminum substrate. In some examples, the nickel coating covers all surfaces of the aluminum substrate.

[0112] Scanning electron microscope (SEM) or transmission electron microscope (TEM) observation shows that the nickel coating prepared by the first electroplating treatment described above in the embodiment of the present disclosure has a unit cell diameter of less than or equal to 100 nm, and the nickel coating has a dense lattice, making the nickel coating uniform and dense.

[0113] In step S14, a second electroplating treatment is performed on the second composite material intermediate, so that a second metal coating layer is formed on the surface of the first metal coating layer, thereby obtaining an aluminum-based composite material.

[0114] Exemplarily, the first metal plating layer is a nickel plating layer, the second metal plating layer is a nickel plating layer, and the second electroplating treatment uses a gold plating solution. Since the gold plating layer obtained by electroplating has fine grain growth, a dense and uniform gold plating layer is electroplated on the surface of the nickel plating layer, which can effectively resist oxidation and corrosion.

[0115] In some examples, the gold plating solution provided by the present disclosure includes the following components in the following ratios: 10g / L-20g / L gold trichloride, 50g / L-130g / L sodium sulfite, 30g / L-50g / L ethylenediaminetetraacetic acid, 30g / L-50g / L citric acid, 50g / L-80g / L potassium chloride, and the balance water. The gold plating solution using this formula has the advantages of increasing the plating rate, ensuring uniform coating thickness, a stable and controllable gold plating process, and a dense and smooth gold coating.

[0116] The concentration of gold trichloride includes but is not limited to: 10g / L, 11g / L, 12g / L, 13g / L, 14g / L, 15g / L, 16g / L, 17g / L, 18g / L, 19g / L, 20g / L, etc.

[0117] The concentration of sodium sulfite includes but is not limited to: 50g / L, 55g / L, 60g / L, 65g / L, 70g / L, 75g / L, 80g / L, 85g / L, 90g / L, 95g / L, 100g / L, 105g / L, 110g / L, 115g / L, 120g / L, 125g / L, 130g / L, etc.

[0118] The concentration of EDTA includes but is not limited to: 30 g / L, 33 g / L, 35 g / L, 37 g / L, 40 g / L, 42 g / L, 43 g / L, 44 g / L, 45 g / L, 46 g / L, 47 g / L, 48 g / L, 49 g / L, 50 g / L, etc.

[0119] The concentration of citric acid includes but is not limited to: 30g / L, 32g / L, 35g / L, 38g / L, 39g / L, 40g / L, 42g / L, 43g / L, 44g / L, 45g / L, 46g / L, 47g / L, 48g / L, 49g / L, 50g / L, etc.

[0120] The concentration of potassium chloride includes but is not limited to: 50g / L, 52g / L, 55g / L, 57g / L, 60g / L, 63g / L, 65g / L, 68g / L, 70g / L, 72g / L, 75g / L, 76g / L, 79g / L, 80g / L, etc.

[0121] In some examples, during the gold electroplating process, the current density is 0.1ASD-5ASD, and the electroplating temperature is 30°C-45°C. By limiting the gold electroplating operating parameters as described above, it has the advantages of increasing the plating rate, making the plated film thickness uniform, stabilizing and controlling the gold plating process, and achieving a dense and smooth gold plating layer.

[0122] According to tests, the gold plating rate of the embodiment of the present disclosure can reach 1.5 μm / min, compared with the electroless plating rate of 0.15 μm / min, which shortens the process time of the embodiment of the present disclosure by 5 to 10 times.

[0123] Illustratively, the current density includes, but is not limited to, 0.2ASD, 0.21ASD, 0.22ASD, 0.23ASD, 0.24ASD, 0.25ASD, 0.26ASD, 0.27ASD, 0.28ASD, 0.29ASD, 0.3ASD, 0.31ASD, 0.32ASD, 0.33ASD, 0.34ASD, 0.35ASD, 0.36ASD, 0.37ASD, 0.38ASD, 0.39ASD, 0.4ASD, 0.45ASD, 0.47ASD, 0.5ASD, 0.6ASD, 0.7ASD, 0.8ASD, 0.9ASD, 1ASD, 2ASD, 3ASD, 4ASD, 5ASD, and the like.

[0124] Electroplating temperatures include but are not limited to: 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, etc.

[0125] In some examples, the gold plating time may be 1 minute to 5 minutes, and the thickness of the gold plating layer may be controlled by controlling at least one of the current density and the plating time. For example, the thickness of the gold plating layer may be 0.1 μm to 2 μm.

[0126] The gold coating has a purity of up to 99.9%, being pure gold without any impurity atoms, and is capable of completely covering the nickel coating. In some examples, the gold coating covers all surfaces of the nickel coating. Post-processing may be performed, depending on actual needs, to remove the gold and nickel coatings from one or more surfaces, thereby exposing the aluminum substrate to one or more surfaces of the aluminum-based composite material. Of course, at least one surface of the aluminum-based composite material may have both the gold and nickel coatings.

[0127] SEM or TEM observations show that the gold plating layer prepared by the second electroplating treatment according to the embodiment of the present disclosure has a unit cell diameter of less than or equal to 100 nm and a dense lattice in the gold plating layer, making the gold plating layer uniform and dense.

[0128] In some possible implementations, the method for preparing the aluminum-based composite material provided in the embodiment of the present disclosure also includes: before the purified aluminum-based substrate is galvanized, the surface of the purified aluminum-based substrate is etched to form a rough structure on the surface of the purified aluminum-based substrate, and the rough structure is used to enhance the bonding force between the aluminum-based substrate and the nickel plating layer.

[0129] Referring to FIG. 2 , the method for preparing the aluminum-based composite material provided by the embodiment of the present disclosure includes:

[0130] Step S21 : purifying the aluminum-based substrate to obtain a purified aluminum-based substrate.

[0131] Step S22: performing surface etching treatment on the cleaned aluminum-based substrate to form a rough structure on the surface of the cleaned aluminum-based substrate.

[0132] Step S23: forming a metal protective layer on the surface of the aluminum-based substrate having the rough structure to obtain a first composite material intermediate.

[0133] Step S24: performing a first electroplating treatment on the first composite material intermediate, so that the metal protective layer is corroded by the first metal plating layer, thereby forming a first metal plating layer on the surface of the aluminum-based substrate, and obtaining a second composite material intermediate.

[0134] Step S25 : performing a second electroplating treatment on the second composite material intermediate, so that a second metal coating layer is formed on the surface of the first metal coating layer, thereby obtaining an aluminum-based composite material.

[0135] The etching process creates a roughened surface structure on the cleaned aluminum substrate, increasing its specific surface area. This helps strengthen the bond between the aluminum substrate and the first metal coating. The roughened surface structure is micro-nanoscale, ensuring enhanced surface adhesion without compromising surface flatness.

[0136] In some examples, to make the size (e.g., depth) of the roughness structure more controllable, the cleaned aluminum-based substrate is subjected to surface etching in an etching solution. The size of the resulting roughness structure can be controlled by controlling the etching time.

[0137] Exemplarily, the etching solution includes the following components in the following proportions, which have the advantages of low etching rate and uniform etching: 10g / L-50g / L of tetramethylammonium hydroxide, 10g / L-50g / L of disodium ethylenediaminetetraacetic acid (EDTA2Na), 5g / L-20g / L of zinc oxide, 5g / L-20g / L of barbituric acid, 0.1g / L-1g / L of soluble silver salt, and water as the balance so that the pH value of the etching solution is 10-13.

[0138] The concentration of tetramethylammonium hydroxide includes but is not limited to: 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, etc.

[0139] The concentration of disodium edetate includes but is not limited to: 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, etc.

[0140] The concentration of zinc oxide includes but is not limited to: 5g / L, 8g / L, 10g / L, 12g / L, 15g / L, 16g / L, 18g / L, 20g / L, etc.

[0141] The concentration of barbituric acid includes but is not limited to: 5g / L, 7g / L, 10g / L, 12g / L, 15g / L, 17g / L, 18g / L, 20g / L, etc.

[0142] The soluble silver salt can be silver nitrate, silver fluoride, silver chlorate, silver perchlorate, etc. The concentration of the soluble silver salt includes but is not limited to: 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, etc.

[0143] In some examples, the cleaned aluminum-based substrate can be placed in an etching solution and immersed at 20° C. to 40° C. for 1 to 5 minutes to perform surface etching treatment, thereby obtaining a micro-nano-sized rough structure on the surface of the aluminum-based substrate. For example, the immersion temperature includes, but is not limited to, 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C., 30° C., 31° C., 32° C., 33° C., 34° C., 35° C., 36° C., 37° C., 38° C., 39° C., 40° C., etc. The immersion time includes, but is not limited to, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, etc.

[0144] In summary, the preparation method of the aluminum-based composite material provided in the embodiment of the present disclosure can effectively avoid the phenomena of loose plating and nickel nodules in chemical nickel-gold, eliminate adverse factors such as black disk and Giovanni effect, and is easy to operate, low in cost, and can effectively protect the aluminum-based substrate.

[0145] On the other hand, an embodiment of the present disclosure provides an aluminum-based composite material, which includes an aluminum-based substrate, a first metal coating, and a second metal coating arranged in sequence, wherein the unit cell diameter of the first metal coating is less than or equal to 100 nm, and the unit cell diameter of the second metal coating is less than or equal to 100 nm.

[0146] The unit cell diameter of the first metal coating involved in the embodiments of the present disclosure refers to the diagonal length of a single unit cell in an SEM image of a unit cell of the first metal coating. The unit cell diameter of the second metal coating involved in the embodiments of the present disclosure refers to the diagonal length of a single unit cell in an SEM image of a unit cell of the second metal coating.

[0147] Exemplarily, the first metal coating is a nickel coating, the second metal coating is a gold coating, and the aluminum-based composite material includes an aluminum-based substrate, a nickel coating, and a gold coating arranged in sequence, wherein the unit cell diameter of the nickel coating is less than or equal to 100 nm; the unit cell diameter of the gold coating is less than or equal to 100 nm.

[0148] The unit cell diameter of the nickel plating layer and the unit cell diameter of the gold plating layer can be measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0149] The unit cell of a nickel (Ni) crystal is a face-centered cubic (FCC) close-packed structure, with one nickel atom located at each of the eight vertices and six faces of the cube. The unit cell diameter of the nickel coating described in the present disclosure refers to the diagonal length of a single unit cell in a SEM image of the unit cell of the nickel coating.

[0150] The unit cell of a gold (Au) crystal is a face-centered cubic (FCC) close-packed structure, with a gold atom located at each of the eight vertices and six face centers of the cube. The unit cell diameter of the gold coating described in the present disclosure refers to the diagonal length of a single unit cell in a SEM image of the unit cell of the gold coating.

[0151] The aluminum-based composite material provided by the embodiment of the present disclosure has a unit cell diameter of the nickel plating layer less than or equal to 100 nm, and the lattice in the nickel plating layer is dense, so that the nickel plating layer is uniform and dense. The unit cell diameter of the gold plating layer is less than or equal to 100 nm, and the lattice in the gold plating layer is dense, so that the gold plating layer is uniform and dense, and the covering effect on the nickel plating layer is excellent. The dense nickel plating layer and the gold plating layer avoid the mutual diffusion of nickel and gold elements, thereby avoiding the Galvani effect and the black pad problem, which not only improves the stability of the nickel plating layer and the gold plating layer, making their corrosion resistance and oxidation resistance more stable, but also the gold plating layer with a flat surface and uniform texture is also conducive to welding and gold wire bonding.

[0152] In some implementations, after testing, in the aluminum-based composite material provided by the embodiment of the present disclosure, the surface roughness Ra of the nickel plating layer is ≤ 20 nm.

[0153] The surface roughness of the gold plating layer is Ra≤20nm.

[0154] Based on the above parameters, it can be seen that both the nickel plating layer and the gold plating layer maintain a relatively high flatness, which is particularly beneficial for improving their density, oxidation resistance, corrosion resistance and other properties.

[0155] In some possible implementations, a rough structure is provided on the surface of the aluminum-based substrate that is bonded to the nickel-plated layer. The rough structure is used to enhance the bonding between the aluminum-based substrate and the first metal coating, such as the nickel coating, thereby ensuring stable adhesion of the first metal coating to the aluminum-based substrate. The formation method and dimensions of the rough structure are as described above.

[0156] In some examples, the aluminum-based composite material may be a pad structure.

[0157] On the other hand, an embodiment of the present disclosure further provides an electronic device, which includes a device body and a pad structure, wherein the pad structure is connected to the device body, and the pad structure is prepared from any one of the above-mentioned aluminum-based composite materials.

[0158] The manufacturing method described above can be used to directly process a device body with an aluminum-based material pad, and the aluminum-based material pad can be sequentially plated with a metal protective layer (e.g., zinc layer), a first metal plating layer (e.g., electroplated nickel), and a second metal plating layer (e.g., electroplated gold). Alternatively, a finished aluminum-based composite material can be used to directly manufacture the pad structure, and then the pad structure can be connected to the device body.

[0159] The electronic device provided by the embodiment of the present disclosure has all the advantages of the aluminum-based composite material provided by the embodiment of the present disclosure.

[0160] In some examples, the electronic device includes but is not limited to: chips, printed circuit boards, etc., and a pad structure is arranged on the chip and the printed circuit board, and the pad structure includes a conductive column and a pad, wherein the conductive column is the above-mentioned aluminum-based substrate, and the pad is the above-mentioned stacked first metal plating layer and the second metal plating layer, for example, a nickel plating layer and a gold plating layer, respectively.

[0161] Electronic devices such as chips and printed circuit boards use a pad structure based on the aluminum-based composite material described in the embodiments of the present disclosure, which not only enables efficient and reliable welding operations, but can also be further used for gold wire bonding and plastic packaging.

[0162] Some specific embodiments of the present disclosure will be described in more detail below. Although preferred embodiments of the present disclosure are described below, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0163] Example 1-Example 3

[0164] Examples 1 to 3 respectively provide a method for preparing an aluminum-based composite material and an aluminum-based composite material obtained based on the preparation method. The preparation methods of the aluminum-based composite materials involved in Examples 1 to 3 are as follows, with the difference being the parameters shown in Table 1:

[0165] Step 1: Place the aluminum-based substrate in a decontamination solution and soak it at 50° C. for 5 minutes. Use the decontamination solution to decompose organic impurities such as grease and dirt on the aluminum-based substrate to obtain a purified aluminum-based substrate.

[0166] The impurity removal solution includes the following components in the following proportions: 20 g / L sodium hydroxide, 30 g / L sodium carbonate, 10 g / L sodium phosphate, 10 g / L dimethylamine borane, 50 g / L nonylphenol polyoxyethylene ether, and water as the balance so that the pH value of the impurity removal solution is 9.

[0167] Step 2: Place the cleaned aluminum-based substrate in an etching solution and soak it at 30° C. for 2 minutes to perform surface etching on the aluminum-based substrate.

[0168] The etching solution includes the following components in the following proportions: 30 g / L tetramethylammonium hydroxide, 30 g / L EDTA2Na, 10 g / L zinc oxide, 10 g / L barbituric acid, 5 g / L silver nitrate, and water as the balance so that the pH value of the etching solution is 13.

[0169] Step 3: Place the purified aluminum-based substrate in a galvanizing solution and perform galvanizing treatment at 25°C for 10 minutes. Then, place it in a nitric acid solution with a mass concentration of 30% and pickle it at 25°C for 2 minutes. Then, continue to place it in a new galvanizing solution and perform galvanizing treatment at 25°C for 8-15 minutes to form a zinc layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate.

[0170] The thickness of the formed zinc layer is determined by the time of the secondary galvanizing. The thickness of the zinc layer in each embodiment can be found in Table 1. The zinc plating solution includes the following components in the following proportions: 100 g / L sodium hydroxide, 30 g / L potassium sodium tartrate, 5 g / L zinc oxide, 1 g / L ferric chloride, and water as the balance to achieve a pH of 13.

[0171] Step 4: electroplating the first composite material intermediate with nickel so that the metal protective layer is corroded by the nickel plating solution, thereby forming a nickel plating layer on the surface of the aluminum-based substrate to obtain a second composite material intermediate.

[0172] The thickness of the nickel plating layer formed is determined according to the time of the nickel electroplating treatment. The time of the nickel electroplating treatment and the thickness of the nickel plating layer in each embodiment can be seen in Table 1.

[0173] During the nickel electroplating treatment, the current density is 1.5ASD, the electroplating temperature is 55°C, and the nickel plating solution used includes the following components: 30g / L nickel sulfate, 25g / L nickel chloride, 20g / L nickel methanesulfonate, 30g / L hydrochloric acid, 8g / L diphenylsulfonylsulfinic acid (BBI), 0.5g / L sodium styrenesulfonate, and the balance is water.

[0174] Step 5: electroplating the second composite material intermediate with gold, so that a gold plating layer is formed on the surface of the nickel plating layer, thereby obtaining an aluminum-based composite material.

[0175] The thickness of the gold plating layer formed is determined according to the time of the gold electroplating treatment. The time of the gold electroplating treatment and the thickness of the gold plating layer in each embodiment can be seen in Table 1.

[0176] During the gold electroplating treatment, the current density is 0.3ASD, the electroplating temperature is 37°C, and the gold plating solution used includes the following components: 15g / L gold trichloride, 100g / L sodium sulfite, 45g / L ethylenediaminetetraacetic acid, 30g / L citric acid, 60g / L potassium chloride, and the balance is water.

[0177] Comparative Example 1-Comparative Example 2

[0178] Comparative Examples 1 and 2 respectively provide aluminum-based composite materials obtained based on chemical plating. Before chemical nickel plating and chemical gold plating, Comparative Examples 1 and 2 sequentially perform purification, etching and galvanizing on the aluminum-based substrates. The purification, etching and galvanizing processes can refer to the purification, etching and galvanizing processes described in Examples 1 to 3.

[0179] The chemical nickel plating solution used in the chemical nickel plating was a commercial product purchased from Uyemura Company and the model was NMR-2. The chemical nickel plating temperature was 80° C. and the time was 15 min.

[0180] The chemical gold plating solution used in the chemical gold plating was a commercial product purchased from Uyemura and the models were TUF-1 (Comparative Example 1) and TUF-41 (Comparative Example 2). The chemical gold plating temperature of Comparative Example 1 was 74° C., and the chemical gold plating temperature of Comparative Example 2 was 50° C.

[0181] Some parameters that differ in the aluminum-based composite materials and preparation methods provided in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1.

[0182] Table 1

[0183] Test Example 1

[0184] According to the package wire bonding strength test performed in accordance with the standard JESD22-B116, this test example 1 performs a gold wire bonding (gold wire bonding) solder joint tensile test on the aluminum-based composite materials provided in Examples 1-3 and Comparative Examples 1-2.

[0185] The minimum tensile strength of the solder joints obtained from the tensile test of the gold wire bonding solder joints is shown in Table 2.

[0186] Table 2

[0187] As shown in Table 2, in the aluminum-based composite materials provided in Examples 1-3, after the coating is used as a pad and bonded to a gold wire, the bonding strength is stronger than that of the control example, which indicates that the obtained coating is flat and uniform, with high density, which is conducive to improving the gold wire bonding effect.

[0188] Test Example 2

[0189] In Test Example 2, SEM analysis was performed on the surface morphology of the nickel coatings in the aluminum-based composite materials provided in Example 1 and the aluminum-based composite materials provided in Comparative Example 2. The nickel coatings were exposed on the surface of the aluminum-based substrate of the second composite intermediate. In other words, SEM analysis was performed on the nickel coatings of the second composite intermediates of the corresponding aluminum-based composite materials. See Figures 3 and 4 for the test results.

[0190] FIG3 illustrates the magnified morphology of the nickel plating layer of the aluminum-based composite material provided in Example 1 at different magnifications, wherein the magnifications of the scanning electron microscope are 1K, 5K, 20K, 50K, and 100K, respectively.

[0191] FIG4 illustrates the magnified morphology of the nickel plating layer of the aluminum-based composite material provided in Comparative Example 1 at different magnifications, wherein the magnifications of the scanning electron microscope are 1K, 5K, 20K, 50K, and 100K, respectively.

[0192] As shown in FIG3 , the nickel coating of the aluminum-based composite material provided in Example 1 has a flat and uniform surface, a dense lattice, no nodules and holes, and a small unit cell size (<100 nm), which makes it highly stable and can effectively resist oxidation and corrosion.

[0193] As shown in FIG4 , the nickel plating layer of the aluminum-based composite material provided in Comparative Example 1 has a nodular surface, a large unit cell size (>200 nm), poor flatness, and a small number of holes in some areas, which makes it unstable and easily accelerates corrosion.

[0194] In this Test Example 2, SEM tests were performed on the surface morphologies of the gold plating layers in the aluminum-based composite material provided in Example 1 and the aluminum-based composite material provided in Comparative Example 2. The test results are shown in FIG5 and FIG6 .

[0195] FIG5 illustrates the magnified morphology of the gold-plated layer of the aluminum-based composite material provided in Example 1 at different magnifications, wherein the magnifications of the scanning electron microscope are 1K, 5K, 20K, 50K, and 100K, respectively.

[0196] FIG6 illustrates the magnified morphology of the gold-plated layer of the aluminum-based composite material provided in Comparative Example 1 at different magnifications, wherein the magnifications of the scanning electron microscope are 1K, 5K, 20K, 50K, and 100K, respectively.

[0197] As shown in FIG5 , the gold-plated layer of the aluminum-based composite material provided in Example 1 has a flat and uniform surface, a dense lattice, no nodules and holes, and a small unit cell size (<100 nm), which makes it highly stable and can effectively resist oxidation and corrosion.

[0198] As shown in FIG6 , the gold-plated layer of the aluminum-based composite material provided in Comparative Example 1 continues the surface morphology of the nickel-plated layer, has poor film continuity, and has loose grain boundaries, resulting in poor stability and easy accelerated corrosion.

[0199] The above description is only for the purpose of facilitating those skilled in the art to understand the technical solutions of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A method for preparing an aluminum-based composite material, wherein: The preparation method of the aluminum-based composite material comprises: Purifying the aluminum-based substrate to obtain a purified aluminum-based substrate; forming a metal protective layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate; Performing a first electroplating treatment on the first composite intermediate so that the metal protective layer is corroded to form a first metal plating layer on the surface of the aluminum-based substrate to obtain a second composite intermediate; The second composite material intermediate is subjected to a second electroplating treatment to form a second metal coating layer on the surface of the first metal coating layer, thereby obtaining the aluminum-based composite material.

2. The method for preparing the aluminum-based composite material according to claim 1, wherein: The metal protective layer includes a zinc layer.

3. The method for preparing the aluminum-based composite material according to claim 2, wherein: The step of forming a metal protective layer on the surface of the purified aluminum-based substrate to obtain a first composite material intermediate comprises: Placing the purified aluminum-based substrate in a zinc plating solution for zinc plating, forming a zinc layer on the surface of the purified aluminum-based substrate, and obtaining a first composite material intermediate; The zinc plating solution comprises the following components: 50g / L-200g / L of sodium hydroxide, 5g / L-50g / L of potassium sodium tartrate, 1g / L-10g / L of zinc oxide, 0.2g / L-2g / L of iron and ferrous compounds, and water as the balance so that the pH value of the zinc plating solution is 12-14.

4. The method for preparing the aluminum-based composite material according to claim 1, wherein: The thickness of the metal protection layer is 1nm-100nm.

5. The method for preparing the aluminum-based composite material according to any one of claims 1 to 4, wherein: The first metal coating comprises a nickel coating or a nickel-phosphorus alloy coating; The second metal plating layer includes a gold plating layer.

6. The method for preparing the aluminum-based composite material according to claim 5, wherein: The first metal coating is a nickel coating, and the first electroplating treatment uses a nickel plating solution, which includes components in the following proportions: 1g / L-50g / L nickel sulfate, 1g / L-50g / L nickel chloride, 1g / L-50g / L nickel methanesulfonate, 1g / L-50g / L hydrochloric acid, 1g / L-10g / L main brightener, 0.1g / L-1g / L auxiliary brightener, and the balance is water.

7. The method for preparing the aluminum-based composite material according to claim 6, wherein: When performing the first electroplating treatment, the current density is 0.1ASD-5ASD, and the electroplating temperature is 45°C-65°C.

8. The method for preparing the aluminum-based composite material according to claim 5, wherein: The second metal plating layer is a gold plating layer, and the second electroplating treatment adopts a gold plating solution, which includes components in the following proportions: 10g / L-20g / L of gold trichloride, 50g / L-130g / L of sodium sulfite, 30g / L-50g / L of ethylenediaminetetraacetic acid, 30g / L-50g / L of citric acid, 50g / L-80g / L of potassium chloride, and the balance is water.

9. The method for preparing the aluminum-based composite material according to claim 8, wherein: When the second electroplating treatment is performed, the current density is 0.1ASD-5ASD, and the electroplating temperature is 30°C-45°C.

10. The method for preparing the aluminum-based composite material according to any one of claims 1 to 9, wherein: The method for preparing the aluminum-based composite material further comprises: before the purified aluminum-based substrate is subjected to galvanizing, the purified aluminum-based substrate is subjected to surface etching treatment, so that a rough structure is formed on the surface of the purified aluminum-based substrate; The rough structure is used to enhance the bonding force between the aluminum-based substrate and the first metal coating layer.

11. The method for preparing the aluminum-based composite material according to claim 10, wherein: The surface etching treatment is performed by placing the cleaned aluminum-based substrate in an etching solution; The etching solution comprises the following components: 10g / L-50g / L tetramethylammonium hydroxide, 10g / L-50g / L disodium ethylenediaminetetraacetate, 5g / L-20g / L zinc oxide, 5g / L-20g / L barbituric acid, 0.1g / L-1g / L soluble silver salt, and water as the balance so that the pH value of the etching solution is 10-13.

12. An aluminum-based composite material, wherein: The aluminum-based composite material comprises an aluminum-based substrate, a first metal coating and a second metal coating which are sequentially stacked; The unit cell diameter of the first metal coating is less than or equal to 100 nm; The unit cell diameter of the second metal coating layer is less than or equal to 100 nm.

13. The aluminum-based composite material according to claim 12, wherein: The aluminum-based substrate has a rough structure on its surface combined with the first metal coating layer, and the rough structure is used to enhance the bonding force between the aluminum-based substrate and the first metal coating layer.

14. An electronic device, wherein: The electronic device comprises a device body and a pad structure connected to the device body, and the pad structure is prepared using the aluminum-based composite material according to any one of claims 12-13.

15. The electronic device according to claim 14, wherein The electronic device includes: a chip and a printed circuit board.

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