KR100824009B1 - Plating method for cellular phone frame - Google Patents

Abstract

A plating method for a cellular phone frame die-casting molded from an aluminum-magnesium alloy is provided to substantially lower the defective proportion of a product by preventing distortion after demolding and removing burrs during a sprue cutting, punching and post-treatment easily and neatly, and improve productivity by preventing distortion phenomena from generating even when heating the die-casting molded frame after adding acids and bases to a die-casting molded frame in the coating processes. A plating method for a cellular phone frame die-casting molded from an aluminum-magnesium alloy comprises: a step of injecting an alloy melt comprising 8.940 to 9.940 wt.% of Mg, 0.400 to 0.460 wt.% of Fe, 0.400 to 0.460 wt.% of Mn, 0.100 to 0.200 wt.% of Si, 0.060 to 0.100 wt.% of Cu, 0.020 to 0.040 wt.% of Zn, 0.008 to 0.012 wt.% of Cr, 0.008 to 0.010 wt.% of Sn, 0.008 to 0.010 wt.% of Ti, 0.007 to 0.009 wt.% of Ni, 0.005 to 0.007 wt.% of Pb, and the balance of Al and other inevitable impurities into a mold cavity to die-casting mold a frame; and a step(CP) of coating chromium on the die-casting molded frame. The plating method further comprises a nickel coating step(NP) in prior to the chromium coating step. The plating method further comprises a corrosion resistance reinforcement layer-forming step between the nickel coating step and the chromium coating step. The plating method further comprises a color coating step(CC) which consists of a process(CC1) of forming a masking layer on the die-casting molded frame through printing, a process(CC2) of coating a color on the masking layer-formed frame, and a process(CC3) of washing the masking layer between the nickel coating step and the chromium coating step.

Description

Plating method of mobile phone frame die cast with aluminum-magnesium alloy {PLATING METHOD FOR CELLULAR PHONE FRAME}

The present invention relates to a plating method of a mobile phone frame die cast with an aluminum-magnesium alloy,

More specifically, as an alloy for multicasting, Mn, Si, Cu, Zn, Cr, Sn, Ti, Ni, and Pb are mixed in a predetermined amount in an aluminum-magnesium alloy known to be excellent in corrosion resistance, strength, and stretchability. Due to the component properties, it satisfies characteristics such as corrosion resistance, abrasion resistance, impact resistance, and yield strength, which are essential for mobile phones, and the addition of tin and lead increases moldability and machinability,

As a result, warping is prevented after demolding and burrs can be easily and neatly removed during cutting, punching and post-treatment, which can significantly reduce the product defect rate for the frame for the mobile phone or the bracket for the LCD.

In particular, in the case of plating on the die cast frame using such an alloy, even if an acidic group is added and heated in the plating process, there is no distortion phenomenon, thereby improving productivity.

The aluminum alloy applied to diecast should meet the requirements of good fluidity during melting, low hot brittleness, good melt spreadability for solidification shrinkage and no sticking to the mold.

In particular, Al-Mg-based alloys are known to be excellent in corrosion resistance, strength, elongation, low specific gravity and good machinability.

Registered Patent of Daewon Alloy Co., Ltd. No. 0711660 (2007.07.16) `` Aluminum-Magnesium Alloy for Mobile Phone and Electronic Product Interior and Exterior ''

By weight% Mg 11-14%, Fe 0.5% or less, Si 0.01-0.5%, Mn 0.1-0.5%, Ti 0.01-0.3%, Co 0.01-0.2%, Be 0.003-0.02%, balance Al and other unavoidable The aluminum-magnesium alloy has a tensile strength of 250 N / mm 2 or more, a hardness of 60 HBW or more, and a Charpy absorption energy of 1.0 J or more, thereby providing an alloy having excellent hardness and impact resistance. ,

In particular, the present invention proposes an alloy composition suitable for die casting of an electronics case such as a mobile phone or a notebook, which tends to be light and small.

However, the inventor of the present invention, which has been engaged in die casting industry related to mobile phone parts for many years,

During the process of cutting the ball through die casting and removing the bur during punching and post-treatment, the bur can not be removed neatly, causing defects, and finding distortion during additional plating, painting, and other post-processing of the frame. It became.

In particular, the disadvantages of the above-mentioned patent is that in the case of heat or physical impact applied in the post-processing process such as plating process or cutting to the thin-thin product in accordance with the tendency of light and short, the productivity and cost competitiveness, even completed The quality of the phone will also be seriously affected.

In addition, when exposed and heated to acidic acid during plating, painting, and drying process, high corrosion resistance and heat resistance can be used to reduce defects. In the case of alloys applied to frames of mobile phones, LCD brackets, and other electronic products, such hot brittleness It lacks corrosion resistance and heat resistance.

The present invention has been proposed to solve the problems of die-casting aluminum-magnesium alloy, in particular Patent No. 0741660.

Accordingly, the present invention is to prevent the occurrence of wear and breakage due to friction in the process of casting and finishing and stability of post-processing, and the nature of the mobile phone opening and closing (folder type) or sliding process (slide type)

Compared with the registered patent component, additionally, Cu for reducing adhesion and strengthening of solid solution, Zn for improving corrosion resistance and strength, Cr for improving wear resistance, Sn and Pb for improving moldability and machinability, and Ni for improving heat resistance are further introduced. So,

Mechanical properties (impact resistance, etc.) as well as increased die casting quality (Cu) and stable post-treatment processes such as burr removal after demolding (Sn and Pb), warping or damage in plating and other post-processing processes It is an object of the present invention to provide a die-casting alloy for a mobile phone frame and a method of manufacturing a mobile phone frame using the same, in order not to generate (Ni and Zn) and to maintain strength and shape even in a finished mobile phone (Cr).

In the present invention, a mobile phone frame manufactured based on such an alloy additionally incorporates a post-processing process such as plating or black plating, and in particular, an object of the present invention is to provide a product having a gorgeous and stable plating quality through various plating methods.

In order to achieve the above object, the die-casting aluminum-magnesium alloy for a mobile phone frame according to the present invention is

8.940 ~ 9.940 wt% Mg for improving corrosion resistance and tensile strength,

0.400 ~ 0.460 wt% Fe for improved demolding performance by reducing tack

0.400 to 0.460 wt.% Mn to enhance corrosion resistance and to aid in the addition of Fe,

0.100 to 0.200% by weight of Si for improved flowability, reduced shrinkage, and improved heat resistance of the melt,

0.060 ~ 0.100 wt% Cu for reduced tack and strengthen solid solution,

Zn of 0.020 ~ 0.040 wt% for corrosion resistance and strength improvement,

0.008 ~ 0.012 wt% Cr, for improved wear resistance

0.008% to 0.010% by weight of Sn for improved formability and machinability,

0.008 ~ 0.010 wt% Ti for corrosion resistance and strength improvement

0.007% to 0.009% by weight of Ni for improved heat resistance

0.005 to 0.007 wt% Pb for improved machinability,

It contains residual amount of Al and unavoidable impurities.

In addition, the method of manufacturing a mobile phone frame according to the present invention comprises the steps of molding by injecting a molten molten aluminum-magnesium alloy heated to 700 ~ 750 ℃ molten metal into a mold cavity; And chrome-plating the die casted frame.

In addition, the present invention is preferably further subjected to the nickel plating step before the chromium plating step,

Furthermore, it is preferable that a corrosion resistance reinforcing layer forming step is further performed between the nickel plating step and the chromium plating step.

In addition, between the nickel plating step and the chromium plating step, a masking layer is formed by printing on a die casted frame, color plating the frame that has passed through the masking layer formation, and then the color of washing the masking layer. It is preferable that the coating step be further performed.

The die-casting aluminum-magnesium alloy according to the present invention, together with Al as the main component, Mg for improving corrosion resistance and tensile strength, Fe for improving demolding performance by reducing adhesion, Mn for improving corrosion resistance and assisting Fe addition effect, and fluidity of melt As well as using Si for improving heat resistance and Ti for improving corrosion resistance and strength,

In addition, by introducing Cu to reduce adhesion and strengthening of solid solution, Zn to improve corrosion resistance and strength, Cr to improve wear resistance, Sn and Pb to improve moldability and machinability, and Ni to improve heat resistance,

Mechanical properties (impact resistance, etc.) as well as increased die casting quality (Cu) and stable post-treatment processes such as burr removal after demolding (Sn and Pb), warping or damage in plating and other post-processing processes Is not generated (Ni and Zn), and strength and shape can be maintained even in a completed mobile phone (Cr).

When the alloy is cut (peeled) to reveal specific patterns and characters using plating, color coating, and diamond cutter on die-cast frames.

Unlike conventional alloys, it is excellent in corrosion resistance and heat resistance, and is exposed to acidic acid groups during plating, painting, and drying process, and does not cause defects due to distortion and deformation even when heated.

As the dimensional stability of die-casting products is so large, the scattering degree is small, the uniform pattern can be formed at the same position during cutting process by automated peeling technology, so the reproducibility is increased. Beautifulness and eye focus and induction are possible, and when the transparent coating layer is formed thereafter, there is no problem in corrosion resistance at the cutting part.

The die-casting aluminum-magnesium alloy according to the present invention includes Mg, Mn, Si, Cu, Zn, Cr, Sn, Ti, Ni, Pb, and other unavoidable impurities in addition to Al, which is a main material and occupies a residual amount in addition to the remaining components.

The Mg is to improve the corrosion resistance and tensile strength, 8.940 ~ 9.940 weight% is added, if less than that the hardness is lowered and if exceeded due to excessive hardness is lowered fatigue resistance and layer resistance.

The Fe is a typical component for improving the demolding performance by reducing the adhesion, 0.400 ~ 0.460% by weight is added.

The Mn is to enhance the corrosion resistance and to assist the Fe addition effect, 0.400 to 0.460% by weight is added, and increases the softening resistance and improves the surface treatment characteristics at a certain temperature.

The Si is to improve the fluidity of the melt, to reduce the shrinkage rate, and to improve the heat resistance, and 0.100 to 0.200 wt% is added.

The Cu is for reducing the adhesion and strengthening the solid solution (particularly for Mg), and is added in an amount of 0.060 to 0.100% by weight, and gives a certain age-hardening to improve hardness and wear resistance, but exceeds the upper limit of corrosion resistance. Cause degradation.

The Zn is for improving corrosion resistance and strength, and is added in an amount of 0.020 to 0.040% by weight, and exceeds the upper limit to reduce corrosion resistance.

The Cr is for improving abrasion resistance through refinement of crystal grains, and is added in an amount of 0.008 to 0.012% by weight, and contributes to improvement of heat resistance to some extent.

The Sn and the Pb together to improve the formability and machinability, and 0.008 to 0.010% by weight and 0.005 to 0.007% by weight, respectively, and exceeds the upper limit, hot and cold workability is lowered.

The Ti is to improve the corrosion resistance and strength, it is added 0.008 ~ 0.010% by weight.

The Ni is to improve the heat resistance, 0.007 to 0.009% by weight is added, if less than that the heat resistance is lowered, in the case of excess purlin lowers the productivity.

The difference between the components of the alloy described in the above-mentioned patent registration No. 0741660 is Cu for reducing adhesion and strengthening solid solution, Zn for improving corrosion resistance and strength, Cr for improving wear resistance, Sn for improving formability and machinability, and Pb, Ni for improving heat resistance,

Due to such a component difference, damage and deformation are prevented during post-processing such as demoulding, removing burrs, plating, and the like for mobile phones, and reducing defects even if the thickness is made as thin as possible in accordance with the trend of light and short reduction.

This alloy component is molded by a die casting method at a casting temperature of 700 ~ 750 ℃, the die casting method will be omitted herein.

The present invention described above can be understood in more detail through the following examples.

[ Example  : Manufacturing of Mobile Phone Frames]

<Table 1: Composition ratio (wt%) of the alloy component>

Mg Mn Si Cu Zn Cr Sn Ti Ni Pb Al 9.740 0.430 0.180 0.080 0.030 0.010 0.009 0.009 0.008 0.006  Remaining amount

11 kinds of components having a ratio as shown in <Table 1> and a mixture containing inevitable impurities are placed in a crucible, melted and introduced into a mold according to a known method, and then shown in FIGS. 1A and 1B. 10 slide front frames (F) and LCD brackets (B) were manufactured.

The resulting frames and brackets had an average breaking strength (press breaking load) of 18 kg · f / cm2 and an average elasticity (shape strength) of 18 kg · f / cm2. There was no failure.

Frames and brackets that have undergone die casting and post-treatment can be improved in strength and appearance through plating, and can be obtained with a variety of appearance and color through coating.

2 shows various post processing processes associated with plating and painting.

For reference, in the description of this specification with reference to FIG. 2, in a non-strict sense, 'step' (D, NP, CP, CC, DC) means a comprehensive process, and 'process' means each step. Show the detailed process,

The term 'coating' is used when referring to plating and painting without distinction.

Each combination of manufacturing steps associated with FIG. 2 is, for example,

Die casting (D) -chrome plating (CP),

Die casting (D) -nickel plating (NP) -chrome plating (CP),

Die casting (D)-chrome plating (CP)-color coating (CC) (especially black coating (BC) for LCD brackets),

Die casting (D)-nickel plating (NP)-chrome plating (CP)-color coating (CC) (especially black coating (BC) for LCD brackets),

Die Casting (D) -Chrome Plating (CP) -Color Coating (CC) -Diamond Cutting (DC),

Die casting (D) -nickel plating (NP) -chrome plating (CP) -color coating (CC) -diamond cutting (DC),

Die casting (D) -nickel plating (NP) -color coating (CC) -chrome plating (CP), and

Die casting (D)-nickel plating (NP)-color coating (CC)-chrome plating (CP)-diamond cutting (DC), etc.

In consideration of the various possible combinations, arrows related to the process sequence are indicated by solid lines, dotted lines, single-dot chain lines, and double-dot chain lines, respectively.

In addition, hereinafter, the description of FIG. 2 will not describe all the combinations of these various manufacturing steps, but only specific combinations. However, the present invention is not limited by the description of the specific combination.

In the plating process to provide a variety of metal texture with the purpose of strength reinforcement, it is preferable to go through the nickel plating step (NP) and then the chrome plating step (CP) in order to reduce the gloss characteristics, strength and above all,

If a variety of patterns or lettering through the masking method, even when the color coating (CC) step is mainly performed for the chromium plating step (CP) for the purpose of improving the wear resistance is preferably carried out after the color coating.

However, in the case of the LCD bracket B, black coating is performed after chrome plating because it is necessary to prevent diffuse reflection by black coating the inner surface B1 forming the boundary of the opening B4 for the viewing window as shown in FIG. 1B. It is desirable to.

The frame or bracket of the mobile phone which has undergone the die casting step (D) is transferred to a plating facility and subjected to a receipt test to confirm that there are no defects, and then a full nickel plating step is performed (NP).

The nickel plating step (NP) first removes foreign substances and oil on the surface by using an alkaline surfactant, and then washed with running water.

Next, a chemical nickel (Ni) plating process is carried out (NP1), which is to improve the plating quality by forming a conductive film on the surface of the frame or bracket, and uses a commercial grade commercial plating solution. Proceed for 5 to 7 minutes by applying resistance values of ~ 33 ° C, pH 8.3 to 9.3, and 15 mW / cm 2 or less, and then rinse with water.

Subsequently, a copper lactic acid plating process is performed (NP2), which is to form a first electroplating layer on the surface of the frame or bracket so that the surface has ductility and adhesiveness, improves conductivity, and reduces shrinkage expansion coefficient of each plating layer. Using copper sulfate (CuSO ₄ · 5H ₂ O) 200-230g / l, sulfuric acid (H ₂ SO ₄ ) 50-60g / l, chlorine (Cl) 40-60ppm, 20-28 ℃, current 650-750A / CB , 40 ~ 50 minutes under the voltage 3 ~ 4V / CB. Subsequently, it is pickled and neutralized with sulfuric acid and washed with water.

Next, a semi-gloss nickel plating process (NP3) is performed, which is to improve the bonding force between the previous plating layer (copper copper plating layer) and the subsequent plating layer (gloss nickel layer) as a kind of primer.

This semi-gloss nickel plating process uses a mixture of NiSO ₄ 260 ~ 300g / ℓ, NiCl ₂ 30 ~ 40g / ℓ, boric acid 35 ~ 45g / ℓ, 52 ~ 58 ℃, pH 3.9 ~ 4.5, current 650 ~ 750A / CB , 15 ~ 25 minutes under voltage 5 ~ 7V / CB.

Next, the nickel nickel process (NP4) is carried out. Through this process, scratch and corrosion resistance can be improved. NiSO ₄ 250-310 g / l, NiCl ₂ 30-40 g / l, boric acid 35-45 g / L is mixed and used for 13 ~ 17 minutes under 52 ~ 58 ℃, pH 3.9 ~ 4.5, current 750 ~ 850A / CB, voltage 5 ~ 7V / CB.

The difference between the semi-gloss nickel layer and the gloss nickel layer is basically based on the strength of the current density and the kind of the varnish used, and after each process, the recovery process is performed, and after the nickel coating process, water washing is performed. Proceed.

Next, after the nickel plating step, it was considered to adopt a masking method in order to allow a specific pattern or lettering by finally performing a color coating step (CC) for a different color or texture from the nickel plated layer.

The color coating step (CC) first prints a pattern, a number, a logo, etc. on the portion where the previous nickel plating (NP) layer is exposed when the final washing process is performed (CC1). The printing of the masking layer (CC1) may be, for example, silk printing using a printing equipment, and then goes through a drying process.

Subsequently, the plating equipment is used to perform a different color plating process (CC2), which is different from the nickel layer such as tin or satin. It is 52 ~ 58 ℃, pH 3.9 ~ 4.5, current 700 ~ 1100A / CB. , 5 ~ 19 minutes under voltage 5 ~ 7V / CB, the treatment solution is mainly a mixture of NiSO ₄ 470 ~ 520g / ℓ, NiCl ₂ 25 ~ 35g / ℓ, boric acid 30 ~ 40g / ℓ and various metal ions or varnishes Mix a small amount.

Next, using a washing facility to remove the masking layer by ultrasonic cleaning (CC3) for 50 to 70 seconds and washed with water.

If the object is an LCD bracket (B), as shown in Figure 1b, the color coating step (CC) is a black coating step performed on the bracket after the nickel plating step (NP) or chrome plating step (CP) ( Preferably BP).

The LCD bracket (B) is formed with a receiving portion (B2) of a predetermined width for receiving and fixing the outside of the LCD to the outside of the opening (B4) serving as a display window for the LCD, the frame by a rivet or bolt Coupling portion B3 is provided with a plurality of through holes to be fixed to the.

The main object of the black coating step BC is the inner surface B1 around the opening B4, and if the inner surface is merely nickel plated (NP) or chromium plated (CP), the reflection of the LCD is caused by diffuse reflection. It interferes with the uniform brightness and degrades visibility.

Such a black coating may be formed by spraying a paint containing a black pigment, it is possible to repeat the coating and drying several times to improve the coating quality, it is preferable that the matte.

In addition, it is preferable to form fine concavities and convexities on the surface of the bracket plated with a strong alkaline (or strong acid) solution before the black coating in order to improve the bonding force.

In addition, if necessary, anodizing is used to oxidize the surface by electrolysis instead of coating to form a passivation film made of aluminum oxide on the aluminum surface (e.g. aluminum products are added to a sulfuric acid solution containing an iron compound). Dipping and applying a current to form a colored anodized film on the surface), and by forming a thin film mainly composed of chromium (Cr) on the surface of the aluminum by a chemical reaction caused by immersing an aluminum material in a solution containing chromate. The black coating layer can be formed by chemical conversion coating or chromate coating.

Patent When using the alloy and plating and painting technology according to the present invention, the thickness of the finished bracket can be manufactured up to about 0.45mm, which can greatly contribute to the trend of light and small size of the mobile phone.

Next, the chromium plating step (CP) can contribute to improved wear resistance.

First, it is desirable to proceed with the corrosion-resistant reinforcement layer plating step (CP1), which is a porous nickel coatings process in which the microporous coating method developed for the semiconductor manufacturing process or the flat panel display manufacturing process is applied to the general plating field. It is preferable.

The process is using a mixture of NiSO ₄ 220 ~ 270g / l, NiCl ₂ 60 ~ 80g / l, boric acid 35 ~ 45g / l, 55 ~ 61 ℃, pH 3.9 ~ 4.5, current 650 ~ 750A / CB, voltage 6.4 Run for 2-4 minutes under ~ 6.6V / CB, and then rinse off.

This is followed by a chromium activation process (CP2). The process can use commercially available ANKOR ^® NFDS from Enthone, Inc., a subsidiary of Cookson Electronics, UK, using NFDS 2 to 3 g / l, 20 to 30 ° C, under voltage 2 to 4 V / CB. Run for ~ 50 seconds.

Subsequently, the chromium plating process (CP3) uses a mixture of chromium oxide (CrO ₃ ) 210-260 g / l and sulfuric acid (H ₂ SO ₄ ) 0.7-1.3 g / l, 35-41 ° C., current 1600-2000 A / CB After 3 ~ 5 minutes under the voltage of 4.8 ~ 5.8V / CB, it is recovered, washed with water and washed with ion (CP4).

Even though the frame and bracket pursued by the present invention are thinned as much as possible, the deformation does not occur even in the heat applied in the above plating process, thereby increasing the die casting quality as well as the mechanical properties (impact resistance) of the alloy according to the present invention. (Cu), stable post-treatment processes such as removal of burrs during post-demolition work (Sn and Pb), and no distortion or breakage during plating and other post-processing processes (Ni and Zn). This is because the strength and shape can be maintained even in the telephone.

In addition, the thinning is possible because the molten alloy is excellent in fluidity.

Next, a diamond cutting (more specifically, peeling) step (DC) of the frame, which has undergone plating and color coating, may be considered in order to ensure that only a specific part of the painted frame is glossy.

As shown in Figure 1a, due to the cutting portion (F1) formed along the front outer edge of the frame it is possible to the beauty of the appearance and induction of eyes.

If the alloy quality is not satisfactory, not only the defect rate of the die-casting product itself is high, but also the dimensional uniformity is not satisfactory, and the repeating error is large. The yield will drop by that much.

However, due to the alloy performance according to the invention significantly reduced shrinkage difference during the curing process,

To eliminate burr, it is possible to trim by using press at the time of degating rather than to remove burr, which improves the work efficiency.

In addition, even in the cutting of diamonds, even a precise cutting pattern can be formed to significantly reduce defects.In order to cut the diamond of the frame, the jig of the press moves in a cylindrical manner so that the cutting by the diamond cutter while pressing the front of the frame uniformly. Work is possible.

Subsequently, the frame that has undergone the diamond cutting step may achieve perfection of the method and the rust prevention performance of the cutting surface F1 through the transparent protective layer forming step DC1.

For example, the transparent protective layer may use an alkylamine compound system, and may further apply a commercially available lacquer enamel resin to compensate for chemical resistance and weather resistance and to obtain a film maintenance gloss.

In the above description, conventionally known techniques related to each alloy, die casting, each plating step and detailed process, a diamond cutting device, etc. are omitted, but those skilled in the art can easily infer, infer, and reproduce them.

In addition, in the above description of the present invention, the present invention has been described in accordance with a specific process order with reference to the accompanying drawings. Various modifications, changes, and substitutions may be made by those skilled in the art. Such modifications, changes, and substitutions are within the scope of protection of the present invention. Should be interpreted as belonging to.

1A and 1B are perspective views of a frame and an LCD bracket for a mobile phone manufactured according to the present invention, respectively;

2 is a process block diagram of a method for manufacturing a frame for a mobile phone according to the present invention.

<Description of the symbols for the main parts of the drawings>

F: Frame F1: Diamond Cutting Part

B: Bracket B1: Black coating inner side

B2: receiving portion B3: engaging portion

Claims (4)

8.940 ~ 9.940% by weight Mg for improved corrosion resistance and tensile strength, 0.400 ~ 0.460% by weight Fe for improving demolding performance by reducing tack, 0.400 ~ 0.460% by weight Mn for improving corrosion resistance and Fe addition effect 0.100 to 0.200% by weight Si for improving fluidity, decreasing shrinkage and heat resistance, 0.060 to 0.100% by weight Cu for decreasing adhesion and strengthening solid solution, 0.020 to 0.040% by weight Zn for improving corrosion resistance and strength, wear resistance 0.008 to 0.012 wt% Cr for improvement, 0.008 to 0.010 wt% Sn for improving formability and machinability, 0.008 to 0.010 wt% Ti for corrosion resistance and strength improvement, 0.007 to 0.009 wt% for improving heat resistance Injecting a molten alloy of Ni, an alloy containing 0.005 to 0.007% by weight of Pb for improving machinability, remaining Al, and an inevitable impurity at 700 to 750 ° C., into a mold cavity; And Step of chrome-plating die cast frame Plating method of the die-cast mobile phone frame made of aluminum-magnesium alloy comprising a. The method of claim 1, wherein before the chromium plating step Plating method of the mobile phone frame die-cast with aluminum-magnesium alloy, characterized in that further through the nickel plating step. The method of claim 2, wherein the nickel plating step and the chromium plating step Plating method of the mobile phone frame die-cast with aluminum-magnesium alloy, characterized in that the step of forming a corrosion-resistant reinforcement layer further. The method of claim 2, wherein the nickel plating step and the chromium plating step The masking layer is formed by printing on the die-cast frame, Color plating the frame that has undergone the masking layer formation, The method of plating a mobile phone frame die-cast with an aluminum-magnesium alloy, characterized in that further comprising a color coating step of washing the masking layer.

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