Aluminum alloy surface treatment method for imparting electrical conductivity

Abstract

An aluminum alloy surface treatment method for imparting electrical conductivity is provided. According to this, an anodized surface has excellent electrical conductivity and durability thereof while having corrosion resistance, high hardness, and wear resistance properties upon anodizing, and thus can be applied to all industrial applications in which an aluminum alloy can be used. In particular, the anodized surface has corrosion resistance, wear resistance, and high hardness properties, and can also be used in components or devices related to antistatic and electromagnetic shielding requiring electrical conductivity. The anodized surface with improved electrical conductivity also exhibits improved heat conduction and heat radiation properties, and thus can be widely used in components of heat exchangers requiring heat dissipation properties, various vehicle components such as engines and wheels, and electronic product components, such as external cases of smartphones and laptop computers.

Description

Aluminum alloy surface treatment method for imparting electrical conductivity

[0001] The present invention relates to a method for treating the surface of an aluminum alloy, and more specifically, to a method for treating the surface of an aluminum alloy to impart electrical conductivity.

[0002] Anodizing is a compound word of anode and oxidizing (Ano-dizing). The oxide film formed by the anodizing process is known to prevent rust on the metal surface and improve wear resistance, heat resistance, adhesion, and aesthetics. In general, metals such as aluminum alloys, titanium alloys, and magnesium alloys naturally form a thin oxide film with high corrosion resistance due to their high reactivity with air in the atmosphere. However, the naturally formed oxide film has limitations in uniformity and corrosion resistance. Therefore, the anodizing surface treatment method is widely used to artificially form an oxide film with uniformity and high corrosion resistance.

[0003]

[0004] Anodized surface-treated aluminum alloys have excellent wear resistance, heat resistance, high strength, and corrosion resistance, and are therefore frequently used as materials for components in various devices.

[0005] However, the anodized aluminum alloy surface has a very high insulating surface resistance, which limits its use in components requiring electrical conductivity on the surface. In addition, the high insulating property makes the surface vulnerable to static electricity prevention, which may cause static electricity-induced damage to electronic components that use the component or electronic components manufactured using the component. For example, the work stage used in semiconductor manufacturing equipment is where the wafer substrate is mounted and is usually made of metal or ceramic materials. When the wafer substrate is placed on the work stage, frictional static electricity is generated between the work stage and the wafer substrate. In addition, the work stage used in a dispenser for an FPD (Flat Panel Display) is usually used to adsorb the display substrate using a vacuum method, and the work stage of the device is also usually made of a metallic material. Therefore, when the display substrate is adsorbed on the work stage or when the adsorbed and fixed display substrate is peeled off from the work stage, there is a problem in that the work stage is charged, which in turn charges the display substrate.

[0006] Accordingly, there is an urgent need for research on a method to provide electrical conductivity to an anodized aluminum alloy surface while ensuring extended durability.

[0007] The present invention has been devised in consideration of the above points, and its purpose is to provide a method for surface treatment of an aluminum alloy capable of forming an anodic oxidation layer having excellent electrical conductivity and durability against electrical conductivity.

[0008] In order to solve the above-described problem, the present invention provides a method for surface treatment of an aluminum alloy to impart electrical conductivity, comprising the steps of (1) pretreating an aluminum alloy, (2) performing a first anodization on the pretreated aluminum alloy to form a first porous layer on the surface of the aluminum alloy, (3) removing the first porous layer, (4) performing a second anodization on the surface of the aluminum alloy from which the first porous layer has been removed to form a second porous layer, and (5) arranging a conductive material within the pores of the second porous layer.

[0009] According to one embodiment of the present invention, the pretreatment may include alkaline degreasing, alkaline etching, and smut removal processes for the aluminum alloy surface.

[0010] In addition, the first anodic oxidation can be performed at a voltage of 40 to 60 V in an aqueous solution electrolytic cell having a temperature of 27 to 35° C., and the second anodic oxidation can be performed at a voltage of 40 to 60 V in an aqueous solution electrolytic cell having a temperature of 27 to 35° C.

[0011] In addition, step (3) can remove the first porous layer by applying an acidic aqueous solution containing 5 to 8 wt% phosphoric acid and 1.5 to 2.5 wt% chromic acid at a temperature of 25 to 35°C for 40 to 70 minutes on the first porous layer.

[0012] Additionally, the first anodization can be performed for 20 to 40 minutes, and the second anodization can be performed for 3 to 7 minutes.

[0013] In addition, step (5) may be performed including step 5-1) processing conductive ink on the second porous layer; and step 5-2) sintering conductive ink.

[0014] In addition, step (5) can process conductive ink having a dynamic surface tension of 25 to 50 mN / m at a bubble life of 1 s of the maximum pressure method at 23°C, thereby disposing the conductive material inside the pores.

[0015] Additionally, a pore expansion process may be further performed between steps (4) and (5) to expand the pores of the second porous layer.

[0016] In addition, the present invention provides an aluminum alloy manufactured by a manufacturing method according to the present invention and having an anodic oxidation layer imparted with electrical conductivity on its surface.

[0017] The aluminum alloy surface treatment method according to the present invention utilizes an anodizing treatment that imparts corrosion resistance, wear resistance, and high hardness characteristics to the aluminum alloy surface, while also imparting electrical conductivity to the aluminum alloy surface. Therefore, it can be utilized in applications where electrical conductivity is essential and thus the use of anodized aluminum alloys was previously limited. In addition, the added electrical conductivity is excellent and uniform, and the durability thereof is excellent. Accordingly, the aluminum alloy surface-treated according to the present invention can be applied to all applications in all industries where aluminum alloys can be used, except for applications where electrical insulation imparted through anodizing is essential, and in particular, it can be applied to parts or devices related to antistatic and electromagnetic shielding that require electrical conductivity while having corrosion resistance, wear resistance, and high hardness characteristics. Furthermore, while thermal conductivity may decrease during simple anodizing, the electrical conductivity provided improves the thermal conductivity and heat radiation characteristics of the anodized surface, and thus can be widely used in various electronic product parts such as heat exchanger parts requiring heat dissipation characteristics, various automobile parts such as engines and wheels, and external cases for smartphones and laptops.

[0018] FIG. 1 is a schematic cross-sectional view of an aluminum alloy manufactured according to one embodiment of the present invention, and is a schematic drawing showing a conductive material arranged in pores within a second porous layer.

[0019] FIG. 2 is a schematic cross-sectional view of each step in a manufacturing process according to one embodiment of the present invention, wherein (a) is a schematic cross-sectional view after the first anodization, (b) is a schematic cross-sectional view of an aluminum alloy surface from which the first porous layer has been removed, and (c) is a schematic cross-sectional view after the second anodization.

[0020] FIG. 3 is an optical microscope photograph formed during a manufacturing process according to one embodiment of the present invention, showing the state of a first porous layer formed during a manufacturing process (left), the state after removing the first porous layer, forming a second porous layer, and performing a pore expansion process (middle), and the state after performing a pore expansion process and performing a conductive ink treatment (right).

[0021] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0022]

[0023] A method for surface treatment of an aluminum alloy according to one embodiment of the present invention may be performed by including (1) a step of pretreating an aluminum alloy, (2) a step of performing a first anodization on the pretreated aluminum alloy to form a first porous layer on the surface of the aluminum alloy, (3) a step of removing the first porous layer, (4) a step of performing a second anodization on the surface of the aluminum alloy from which the first porous layer has been removed to form a second porous layer, and (5) a step of arranging a conductive material within the pores of the second porous layer.

[0024]

[0025] As step (1) of the present invention, a step of pretreating an aluminum alloy is performed.

[0026] The above aluminum alloy may be used without limitation in the case of a known aluminum alloy. For example, the aluminum alloy may be a 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, or 6000 series aluminum alloy, and a specific description regarding a specific alloy belonging to each series is omitted.

[0027] The prepared aluminum alloy undergoes a pretreatment process, and the pretreatment may be performed without limitation as long as it is a known pretreatment performed before anodizing the aluminum alloy. For example, the pretreatment may include alkaline degreasing, alkaline etching, and smut removal processes, and further washing may be included between each process. In addition, since each process belonging to the pretreatment may be performed using known solutions and conditions, the present invention is not particularly limited thereto, and a detailed description thereof will be omitted.

[0028]

[0029] Next, as step (2) of the present invention, a step of performing first anodization on the pretreated aluminum alloy to form a first porous layer on the surface of the aluminum alloy is performed.

[0030] The first anodic oxidation can be performed using a known anodic oxidation method, such as a sulfuric acid method, an oxalic acid method, or a sulfuric acid-oxalic acid mixed acid method. Preferably, the first anodic oxidation can be performed using a sulfuric acid method, which can be advantageous in achieving the purpose of the present invention.

[0031] Specifically, the first anodic oxidation by the hydroxide method can be performed at a constant voltage of 40 to 60 V for 20 to 40 minutes in an hydroxide aqueous solution electrolytic cell at a temperature of 27 to 35°C, and more preferably, it can be performed at a voltage of 45 to 50 V for 20 to 40 minutes in an hydroxide aqueous solution electrolytic cell at a temperature of 27 to 32°C, and the first porous layer formed under these conditions can increase the porosity of the second porous layer performed in step (4) described below while making the pore distribution more uniform, thereby providing more uniform antistatic performance on the aluminum alloy surface. If the temperature of the hydroxide aqueous solution applied in step (2) is less than 27°C, it may be difficult to increase the porosity and / or the uniformity of the pore distribution of the second porous layer created in step (4) described below. In addition, when the temperature of the aqueous solution of oxalic acid exceeds 35℃, the formation of the first porous layer may be uneven, which may significantly reduce the pore uniformity of the second porous layer. In addition, when the voltage is less than 40V, the first porous layer may not grow normally, and if the voltage exceeds 60V, the first porous layer may grow quickly and the layer may not be formed stably. In addition, when the execution time is less than 20 minutes, there is a concern that the pore sites for the growth of the second anodized layer may not be properly arranged, and when it exceeds 40 minutes, there is a concern that the thickness of the first porous layer may become too thick, which may take too long to remove the first porous layer.

[0032] In addition, the aqueous oxalic acid solution may preferably have a concentration of 0.2 to 0.4 mol, which may be advantageous in achieving the purpose of the present invention. If the concentration of the aqueous oxalic acid solution is less than 0.2 mol, the time required to form the first porous layer is prolonged, and it may be difficult to implement a second porous layer having the desired porosity and pore distribution with the first porous layer formed. In addition, if the concentration of the aqueous oxalic acid solution exceeds 0.4 mol, the growth rate of the first porous layer is fast, so in this case as well, it may be difficult to implement a second porous layer having the desired porosity and pore distribution with the first porous layer formed.

[0033]

[0034] Next, as step (3) according to the present invention, a step of removing the first porous layer is performed.

[0035] (3) Step is a step for removing the first porous layer to expose an aluminum surface having a surface morphology that matches the shape of the lower surface of the first porous layer on the aluminum surface from which the first porous layer has been removed, and the surface morphology that matches the shape of the lower surface of the first porous layer acts as a guide surface for pore growth of the second porous layer formed in step (4) described below, thereby further increasing the porosity and implementing a porous layer having a more uniform pore distribution and also having a uniform pore size.

[0036] The removal of the first porous layer can be performed by physical and / or chemical methods, but in order to expose the aluminum alloy surface with a morphology corresponding to the lower surface morphology of the first porous layer, it can be removed through chemical etching, and specifically, the first porous layer can be removed by applying an acidic aqueous solution containing 5 to 8 wt% phosphoric acid and 1.5 to 2.5 wt% chromic acid at a temperature of 25 to 35°C for 40 to 70 minutes on the first porous layer. If the temperature of the acidic solution applied when removing the first porous layer is lower than 25°C, the removal time may be extended or the removal may not be performed properly. In addition, if the temperature of the acid solution exceeds 35°C, not only the first porous layer may be removed, but also the exposed aluminum alloy surface may be partially etched, so that the surface morphology of the aluminum alloy that matches the morphology of the lower surface of the first porous layer may be damaged, and thus it may be difficult to implement the second porous layer having the desired porosity, pore distribution, and pore uniformity.

[0037]

[0038] Next, as step (4) of the present invention, a step of performing a second anodization on the aluminum alloy surface from which the first porous layer has been removed to form a second porous layer is performed.

[0039] (4) Step is an anodic oxidation step, which can be performed using a known anodic oxidation method as in step (2). However, preferably, anodic oxidation can be performed using a sulfuric acid method, and specifically, a second anodic oxidation treatment can be performed for 3 to 7 minutes at a constant voltage of 40 to 60 V in a sulfuric acid aqueous solution electrolytic cell at a temperature of 27 to 35°C, and through this, it can be advantageous to realize a second porous layer having a large porosity and uniform pores and pore distribution as desired by the present invention.

[0040] In addition, the second anodizing treatment time may be shorter than the first anodizing treatment time, and may preferably be performed for 3 to 7 minutes. However, if the second anodizing treatment time is less than 3 minutes, it may be difficult to smoothly implement the second porous layer, and if it exceeds 7 minutes, the depth of the pores may become deeper, and there is a concern that the second porous layer may not grow smoothly according to the pore arrangement derived from the first porous layer, and thus it may be difficult to achieve the purpose of the present invention.

[0041]

[0042] (4) After the second anodic oxidation treatment in step (4) and before performing step (5) described below, a pore expansion process may be further performed to widen the pores of the second porous layer.

[0043] The above pore expansion process can be performed by treating the second porous layer with 2 to 10 wt% of an acidic solution, for example, an aqueous solution of sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid, at 10 to 20°C for 5 to 10 minutes, thereby increasing the filling property of the conductive ink into the pores of the second porous layer, which can be advantageous in further improving the electrical conductivity.

[0044]

[0045] Next, as step (5) of the present invention, a step of arranging a conductive material inside the pores of the second porous layer is performed.

[0046] The conductive material placed inside the above pores imparts electrical conductivity to the surface of the aluminum alloy, and the conductive material may be used without limitation as long as it is a known material having electrical conductivity.

[0047] Specifically, the conductive material in step (5) can be produced by including a step of processing conductive ink on the second porous layer as step 5-1), and a step of sintering the conductive ink as step 5-2).

[0048] Specifically, in step 5-1), the conductive ink contains a conductive component that is the origin of the conductive material, and may include, for example, metal particles such as silver, gold, copper, aluminum, and platinum, or a precursor material that can form metal particles through oxidation-reduction. For example, the conductive ink may be an ink that forms a silver conductive material, and may contain a silver salt as a precursor. The silver salt may preferably have an oxidation state of +1 and may include a ligand, and the conjugate acid of the ligand preferably has a boiling point of 120°C or lower so that it can be removed under mild conditions during processing of the conductive ink. For example, the silver salt can be silver acetate, silver formate, silver carbonate, silver fluoride, silver nitrate, silver nitrite, silver chloride, silver bromide, silver iodide, silver phosphate, silver trifluoroacetate, silver acetylacetonate, silver sulfate, or silver oxide. Preferably, the silver salt is silver acetate. The conjugate acid of the acetate ligand is acetic acid, and the boiling point is about 117 to 118°C.

[0049] In addition, the conductive ink may further include a solvent, a binder resin, and an additive in addition to the conductive component. The binder resin, solvent, and additive may be any of those contained in conventional conductive inks, and the present invention is not particularly limited thereto. For example, the binder resin may contain an epoxy resin, and the solvent may contain at least one selected from the group consisting of butyl carbitol, ethanol, isopropyl alcohol, and ethyl acetate.

[0050] In addition, the additive may be a complexing agent, for example, when the conductive component is a metal salt, and may be specifically an alkylamine. The alkylamine is an amino group substituted with at least one alkyl group having 1 to 8 carbon atoms, and the alkyl group means a hydrocarbon group having a designated carbon number and may be linear, cyclic, branched, or a combination thereof. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, pentyl, isopentyl, cyclohexyl, cyclopentyl, and the like. The alkylamine may be a primary, secondary, or tertiary amine, preferably a primary amine.

[0051] Meanwhile, a weakly basic alkylamine can act as a solvent and stabilizer for the silver salt. The alkylamine may preferably contain at least one selected from the group consisting of propylamine, n-butylamine, amylamine, s-butylamine, diethylamine, triethylamine, iso-butylamine, isopentylamine, 1-methylbutylamine, 1-amino-2-methylbutane, and N-methyldiethylamine.

[0052]

[0053] According to one embodiment of the present invention, the conductive ink can be configured to have a dynamic surface tension of 25 to 50 mN / m, more preferably 25 to 40 mN / m, at a bubble life of 1 s of the maximum pressure method at 23°C, through which the filling property of the conductive ink into the pores in the second porous layer can be significantly improved, and if the dynamic surface tension is outside the above-described range, the filling property of the conductive ink into the pores of the second porous layer can be reduced, and as a result, the electrical conductivity performance can be reduced or the electrical conductivity performance can be implemented to be uneven in each region.

[0054] Meanwhile, for measuring dynamic surface tension using the maximum pressure method, it is possible to use commercially available devices such as the following, but the present invention is not limited thereto. For example, measurement can be made using bubble pressure dynamic surface tension meters BP100 or BP50, dynamic surface tension meters t60, t15, etc. In addition, it is preferable to measure the dynamic surface tension at a bubble life of 1 s, but it is noted that an approximation is also possible from measurements at bubble lives before and after that.

[0055] The above-mentioned conductive ink may be treated by a conventional coating method, and for example, a known coating method such as a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, or spray coater may be used, and the present invention is not particularly limited thereto.

[0056] In addition, drying may be performed after conductive ink treatment. The drying may be performed by natural drying or hot air drying using a known drying device. The specific drying temperature is not particularly limited, but may be performed at 120 to 150°C for 5 to 30 minutes in an IR or circulation oven.

[0057]

[0058] Next, a step of sintering the conductive ink can be performed as step 5-2). The specific conditions for the sintering can be determined depending on the composition of the conductive ink used, and for example, it can be performed at a temperature of 300 to 450°C for 5 to 20 minutes. The sintering can be performed in a conventional furnace, and the present invention is not particularly limited thereto.

[0059]

[0060] An aluminum alloy manufactured according to one embodiment of the present invention described above has an anodized layer having electrical conductivity on its surface, and specifically, the anodized layer may include a conductive material disposed in internal pores.

[0061]

[0062] The present invention will be described in more detail through the following examples, but the following examples do not limit the scope of the present invention, and should be interpreted as helping to understand the present invention.

[0063]

[0064] <Example 1>

[0065] Al1050 aluminum alloy specimens to be anodized were prepared. The pretreatment process of alkaline degreasing, washing, alkaline etching, washing, smut removal, and washing was performed on the Al1050 aluminum alloy specimens. The alkaline degreasing was performed by immersing the specimens in an alkaline degreasing solution containing 7 wt% of an alkaline degreasing component (METEX PS MINCO) at 40°C for about 2 minutes, and then washing. The alkaline-degreasing specimens were then immersed in a 5 wt% sodium hydroxide solution at 60°C for 35 seconds, and then washed, and alkaline etching was performed. The alkali-etched specimens were then immersed in a 20 wt% nitric acid solution at 25°C for 2 minutes, and then washed, and the smut removal process was performed.

[0066] Afterwards, in order to perform the first anodic oxidation treatment, the specimen was placed in an electrolytic cell containing a 0.3 molar concentration aqueous oxalic acid solution as an electrolyte, and anodization was performed for 30 minutes under conditions of 30°C and 50 V constant voltage to form a first porous layer, which is an anodic oxidation layer, on the surface of the specimen.

[0067] Afterwards, to remove the first porous layer, the specimen was immersed in a 30°C mixed solution containing 6 wt% phosphoric acid and 1.8 wt% chromic acid for 60 minutes and then washed with water.

[0068] Afterwards, for the second anodic oxidation treatment, the electrolyte from which the first porous layer was removed was placed in an electrolytic cell containing a 0.3 molar concentration oxalic acid solution, and anodization was performed for 7 minutes under conditions of 30°C and 50 V constant voltage to form a second porous layer, which is an anodic oxidation layer, on the surface of the specimen.

[0069] Afterwards, in order to expand the pores of the second porous layer, the specimen was immersed in a 5 wt% phosphoric acid solution at 15°C for 10 minutes and then washed with water.

[0070] After washing the specimen, a conductive ink containing 15 wt% of silver acetate salt, 2.5 wt% of epoxy binder resin, 7 wt% of propylamine additive, and butyl carbitol as a remaining solvent was spray-coated on the second porous layer, and having a dynamic surface tension of 30.0 mN / m at 23°C using a bubble pressure dynamic tensiometer BP50 and a viscosity of 20.0 cps measured under Brookfield DVII, #61, 100 rpm conditions. The ink was dried in a circulation oven at 140°C for 20 minutes and sintered at 400°C for 10 minutes to manufacture an aluminum alloy specimen having an anodized layer imparted with electrical conductivity.

[0071]

[0072] <Examples 2 to 7>

[0073] An aluminum alloy specimen having an anodized layer imparted with electrical conductivity was manufactured by performing the same process as in Example 1, but changing the temperature for performing the first anodization, the time for performing the second anodization, or the dynamic surface tension of the conductive ink as shown in Table 1 below.

[0074] At this time, Examples 4 to 7 used conductive inks in which the types of additives in the ink were changed to isopropylamine, s-butylamine, diiso-butylamine, and isopentylamine, respectively.

[0075]

[0076] <Comparative Example 1>

[0077] An aluminum alloy specimen was manufactured in the same manner as Example 1, but the removal of the first porous layer and the second anodization were omitted, and an anodized layer with electrical conductivity was provided.

[0078]

[0079] <Experimental Example>

[0080] Electrical conductivity performance was evaluated for Examples 1 to 7 and Comparative Example 1. Specifically, the measurement was performed using a surface resistor, and the measurements were taken at 10 different random points and then expressed as an average value.

[0081] In addition, the standard deviation was calculated for the surface resistance values ​​at 10 different random points, and the surface resistance uniformity was calculated according to Equation 1 below. The smaller the calculated surface resistance uniformity value, the more uniform it can be evaluated.

[0082] [Formula 1]

[0083] Surface resistance uniformity = (Standard deviation of surface resistance at 10 points) × 100 / (Average of surface resistance at 10 points)

[0084]

[0085] In addition, in order to evaluate the durability of electrical conductivity performance, the specimen was immersed in a 1.0 wt% hydrochloric acid solution at 25°C for 20 hours, and the average surface resistance value (A) was calculated using the same method. The average surface resistance value (B) before durability evaluation was used to calculate the surface resistance increase rate using Equation 2 below, and the greater the surface resistance increase rate, the worse the durability can be evaluated.

[0086] Surface resistance increase rate (%) = (A - B) ×100 / B

[0087]

[0088] 1st anodization (temperature / voltage / time) 1st porous layer removal 2nd anodization (temperature / voltage / time) Conductive ink (dynamic surface tension (mN / m) Surface resistance (Ω) Area-by-area surface resistance uniformity (%) Surface resistance increase rate (%) Comparative example 130℃ / 50V / 30 min Not performed Not performed 306.7×10 10 40.046.9 Example 130℃ / 50V / 30 minutesPerformed 30℃ / 50V / 7 minutes 301.2×10 5 3.24.5 Example 224℃ / 50V / 30 minutesPerformed 30℃ / 50V / 7 minutes 302.1×10 65.616.0 Example 330℃ / 50V / 30 minutesPerformed 30℃ / 50V / 15 minutes 301.5×10 6 24.24.4 Example 430℃ / 50V / 30 minutesPerformed 30℃ / 50V / 5 minutes 25.51.9×10 5 3.04.0 Example 530℃ / 50V / 30 minutesPerformed 30℃ / 50V / 5 minutes 20.78.8×10 5 8.64.6 Example 630℃ / 50V / 30minPerformance30℃ / 50V / 5min48.63.0×10 5 5.05.0Example 730℃ / 50V / 30minPerformance30℃ / 50V / 5min55.22.5×10 6 16.75.0

[0089] As can be seen in Table 1, compared to Comparative Example 1, which was formed by forming only the first porous layer and then treating it with conductive ink, Example 1 is superior in electrical conductivity performance and is significantly superior in the uniformity of the electrical conductivity performance by region and durability.

[0090]

[0091] Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiment presented in this specification, and a person skilled in the art who understands the spirit of the present invention will be able to easily propose other embodiments by adding, changing, deleting, or adding components within the scope of the same spirit, but this will also be considered to fall within the spirit of the present invention.

Claims

1. (1) Step of pretreating aluminum alloy; (2) A step of performing first anodization on a pretreated aluminum alloy to form a first porous layer on the surface of the aluminum alloy; (3) A step of removing the first porous layer; (4) a step of performing a second anodization on the aluminum alloy surface from which the first porous layer has been removed to form a second porous layer; and (5) A method for surface treatment of an aluminum alloy to impart electrical conductivity, comprising the step of arranging a conductive material inside the pores of the second porous layer.

2. In paragraph 1, The above first anodic oxidation is performed at a voltage of 40 to 60 V in an aqueous solution electrolytic cell at a temperature of 27 to 35°C. A method for surface treatment of an aluminum alloy to impart electrical conductivity, wherein the second anodization is performed at a voltage of 40 to 60 V in a sulfuric acid aqueous solution electrolytic cell at a temperature of 27 to 35°C.

3. In paragraph 1, (3) A method for surface treatment of an aluminum alloy to impart electrical conductivity, the method comprising applying an acidic aqueous solution containing 5 to 8 wt% phosphoric acid and 1.5 to 2.5 wt% chromic acid at a temperature of 25 to 35°C for 40 to 70 minutes to the first porous layer to remove the first porous layer.

4. In paragraph 2, A method for surface treatment of an aluminum alloy to impart electrical conductivity, characterized in that the first anodization is performed for 20 to 40 minutes and the second anodization is performed for 3 to 7 minutes.

5. In paragraph 1, (4) A method for surface treatment of an aluminum alloy, wherein a pore expansion process is further performed between steps (5) to expand the pores of the second porous layer.

6. In paragraph 1, step (5) 5-1) Step of processing conductive ink on the second porous layer; and 5-2) A method for surface treatment of an aluminum alloy to impart electrical conductivity, comprising a step of sintering conductive ink.

7. In paragraph 1, (5) A method for surface treatment of an aluminum alloy for imparting electrical conductivity, characterized in that the step comprises treating conductive ink having a dynamic surface tension of 25 to 50 mN / m at a bubble life of 1 s of the maximum pressure method at 23°C to place a conductive material inside the pores.

8. An aluminum alloy manufactured according to any one of clauses 1 to 7 and having an anodic oxide layer imparting electrical conductivity on the surface.

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