[0001] Electronic devices, such as keyboards, tablets, laptops, and the like are housed within device covers/casings that have to be aesthetically appealing, while at the same time imparting acceptable mechanical strength, as well as being light in weight. Such device covers may be made of lightweight metal alloys. The outer surface of the casing or device cover, maybe suitably treated to provide a various visual appearances or cosmetic effects.

BRIEF DESCRIPTION OF DRAWINGS

[0002] The following detailed description references the drawings, wherein: [0003] Fig. 1 is a flow chart illustrating a method for forming a glossy casing for an electronic device, according to an example of the present disclosure; [0004] Fig. 2 is a flow chart illustrating a method for forming an enclosure for an electronic device, according to an example of the present disclosure;

[0005] Fig. 3 is a flow chart illustrating a method for forming an enclosure for an electronic device comprising sealing and baking, according to an example of the present disclosure;

[0006] Fig, 4 illustrates a sectional view of an electronic device cover, wherein (a) illustrates a sectional view of an electronic device comprising an injection molded metal casing; (b) illustrates a sectional view of an electronic device cover comprising a injection-molded metal casing and a portion on which chamfering may be done; (c) illustrates a sectional view of an electronic device cover comprising an injection-molded metal casing and anodic layer on the chamfered edge, according to another example of the present disclosure.

DETAILED DESCRIPTION

Definitions

[0007] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are described here. These definitions should be read in the light of the remainder of the present disclosure. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.

[0008] The articles “a", “an”, and “the” are used to refer to one or to more than one (l.e., to at least one) of the grammatical object of the article.

[0009] The term “about" when referring to a numerical value is intended to encompass the values resulting from variations that can occur during the normal course of performing a method. Such variations are usually within pius or minus 5 to 10 percent of the stated numerical value.

[0010] Enclosures, or body of electronic devices, are made of metal casing/frames that have strength, resistance towards corrosion. Examples of this disclosure pertain to suitable materials for such e n clos u res/ca sings, that have aesthetic appeal, are light in weight and at the same time impart acceptable mechanical strength. The examples herein pertain to enclosures/casing/device covers including a thixo-moided magnesium-based alloy into an aluminum alloy casing/frame. As used herein the terms "enclosure” may be used interchangeably with “housing" and "cover or protective cover". Such enciosures may form a back surface of an electronic device and/or any of the edges of the electronic device. [0011] The term "alloy” refers to the class of materials that may be referred to as a solid solution of metals. The aluminum alloy in the present disclosure is selected from AL575, AL1050, All 060, AL1100, AL1199, AL2014, AL2024, AL2219, AL3Q04, AL4041 , AL5GG5, AL5010, AL5019, AL5024, AL5026, AL5050, AL5052, AL5G56, AL5059, AL5083, AL5086, ALS154, AL5182, AL5252, AL5254, AL5356, AL5454, AL5456, AL5457, AL5557, AL5652, ALS657, AL5754, AL6005, AL8005A, AL6060, AL6061, AL8083, AL6066, AL6070, AL6082, AL6105, AL6151 , AL6162, AL6205, AL8282, AL6351 , AL6463, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079, AL7116, AL7129, AL7175, AL7475, AL7178 or combinations thereof. The magnesium-based alloy in the present disclosure is selected from AZ63, AZ81, AZ91, AM50, AM60, AZ31, AZ61, AZ80, AE44, AJ82A, ALZ391 , AMCa602, LZ9, or combinations thereof.

[0012] The term “molded”, and variations, such as “molding”, injecting" used herein refer to injection-molding of alloy. [0013] The term "injection-molding”, or “injecting” used herein refers to the technique for manufacturing parts by injecting molten materia! into a mold or a cavity of another metal. Injection molding may be carried out by a process, such as thixo-moiding or die-casting at a temperature of from about 200 *C to about 500 °C.

[0014] The term "substrate", used herein refers to a frame containing aluminum a!ioy that is used to obtain the device cover of the present disclosure. The substrate can be obtained by Injection-molding techniques, such as thixo- moiding or die-casting.

[0015] The term “chemico-mechanicaliy stable", used herein refers to substrates having high tensile strength and/or high resistance to breakage and/or high corrosion resistance.

[0018] The term “high gloss edges", used herein refers to chamfered surfaces (in particular, the edges) of the substrate that reveal shiny edges.

[0017] Device covers, or body of electronic devices, are made of metal enclosures that have strength, resistance towards corrosion, in particular at chamfered portions, and aesthetic appeal. Metallic device covers or metallic casings or metallic enclosures or metal alloy enclosures are usually regarded as the most premium. Metai alloys, such as aluminum alloy and magnesium-based alloy and the substrates made up of them are soft, prone to corrosion, lack in tensile strength. Therefore, further support treatments are needed.

[0018] In general, the device covers are to be seen as an elegant casing for various electronic devices, such as mobiles, laptops, computers tablets, which would improve the structural integrity and durability of an electronic device without increasing its weight or its manufacturing costs. The employment of magnesium- based substrates, such as magnesium-based alloys, yield poorer finish and durability, and the incorporation of aluminum alloy in the casings might increase the overall weight of the casing. Hence, a balance is to be maintained between the durability and overall weight of the casing. Cases and frames for electronic devices are to have a certain ieve! of durability per unit weight, such that the frame provides adequate protection, but remains suitably light In weight. [0019] Enclosures/casing of electronic devices are chamfered for aesthetic and/or tactile purposes. Chamfering is carried out on portions of the metal substrate, for example, to create rounded edges of keyboards, electronic notebook, laptops, tablets, smartphones, and the like. Surface corrosion tends to occur on chamfered portions of aluminum alloy materials leading to defects on the surface thereby decreasing the edge strength. Although aluminum alloys can offer better durability against corrosion resistance, for example, upon passivation, a purely aluminum alloy-based casing could result in an increase in weight and also aluminum alloys offer relatively poor compatibility with known processing techniques.

[0020] The present subject matter describes a method of forming casing/enclosure for an electronic device wherein anodizing process is carried out at the chamfered edges that forms an anodized layer on the surface of the metal by increasing the natural oxide layer of the metal. The resultant anodic layer may be harder than the underlying metal, providing a coating that provides structural integrity, durability, apart from providing aesthetic appeal at the edges of the electronic device without increasing its weight or its manufacturing costs. [0021] The present subject matter describes examples of injection-molding a magnesium-based alloy into an aluminum alloy casing. The aluminum alloy may be selected from At 575, AL1050, AL1060, All 100, AH 199, AL2014, AL2024, A12219, AL30O4, A14041 , AL50G5, AL5010, AI5019, AL5024, AL5026, A15050, A15052, AL5058, AL5059, A15G83, AL5086, AI5154, AL5182, AL5252, A15254, AL5356, AL5454, AL5456, AL5457, AL5557, AL5652, AL5657, A15754, AL6005, AL6005A, AL6O60, AL6061, A16083, AL6066, AL6070, AL6082, AL6105, AL6151 , AI8162, A16205, AL8262, AL6351 , AL6463, AL7005, AL7022, AL7G68, AL7072, AL7075, A17079, AL7116, AL7129, AL7175, AL7475, AL7178. or combinations thereof. The injection-molded metal substrate results In an overall high tensile strength and an improved corrosion resistance at the chamfered portion and as a consequence, enhanced durability. In an example, the tensiie strength of the alloy, Le,, magnesium-based alloy injection-molded into the aluminum aiSoy casing may be in a range of from about 200 MPa to about 700 MPa as measured by American Society for Testing and Materials (ASTM) D790. This is found to be an enhancement from the magnesium-based alloy having a tensile strength of from about 30 to about 400 MPa. The magnesium-based alloy may be selected from AZ63, AZ81, AZ91 , AM50, AM60, AZ31 , AZ81, AZ80. AE44, AJ62A, ALZ391, AMCa602, LZ91, or combinations thereof. The Injecfion- moiding may be carried out by thixo-molding or die-casiing at a temperature of from about 200 X to about 500 °C. The aluminum alloy substrate may be prefabricated into a suitable format or casing by known processes. The injection- molding of magnesium-based alloy is carried out into the aluminum alloy casing. The injection-molded magnesium-based alloy in the aluminum alloy casing may have a thickness of from about 0.3 mm to about 2.0 mm. Incase the magnesium- based alloy layer has a thickness beyond 2.0 mm, it may lead to substrates that are unsuitable for forming enclosures of electronic devices owing to excess weight. On the other hand, an injection-molded magnesium-based alloy layer having a thickness lower than 0.3 mm may be weak and chemico-mechanicalSy unstable.

[0022] The magnesium-based alloy may be injection-molded into the aluminum alloy casing, such that a portion or the whole of the surface of the magnesium-based alloy layer may be in contact with the aluminum alloy casing/frame.

[0023] Further, the aluminum alloy casing/frame comprising injection- molded magnesium-based alloy Is readily adaptable to techniques, such as passivation, spray coating with a protective layer. Applying the passivation technique allows relatively easy formation of a passivation layer that can provide corrosion resistance to the thus obtained electronic device covers. The passivation layer may have a thickness of from about 1.0 μm to about 15.0 μm. Additionally, spray coating helps in the relatively easy deposition of a protective layer that can provide enhancement of aesthetic appeal of the thus obtained electronic device covers. The protective layer may have a thickness of from about 5.0 μm to about 70.0 μm.

[0024] Chamfering of the injection-molded substrate may provide high gloss finish at the edges. Chamfering may be carried out by a CNG diamond cutting machine. In an example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 5000 to about 90000 rμm for a period in a range of from about 3 to about 8 minutes, in another example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 6000 to about 80000 rμm. Chamfering resuits in an etching that reveals the underlying shiny/pristine aluminum alloy casing/frame, which is then anodized in presence of 150-200 g/L of at least one acid at a potential of from about 5 to about 20 V for a period of from about 20 to about 50 minutes at a temperature of from about 10 X to about 50°C.

[0025] In some examples, chamfering may be carried out on a portion of the casing/frame. The chamfering may be carried out at portions of the casing where a different aesthetic appeal is to be provided as compared to the rest of the casing, such as cover edge, touchpad, cfickpad, fingerprint scanner, edge, or sidewall, area where the logo is to be provided, and the like.

[0026] Further, anodizing at the chamfered areas may provide high gloss finish at those areas. The aesthetic quality of thus obtained device covers may be quantified by measuring a gloss value. In an example, the gloss value of the chamfered portion may be in a range of from about 80 to about 95 units as measured by American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 60". This is found to be an enhancement from the unchamfered portion that may result in a gloss value in the range of from about 60 to about 75 units as measured by American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 60°. In another example, the gloss value of the chamfered portion may be in a range of from about 67 to about 95 units as measured by ASTM D523 at a viewing angie of about 60".

[0027] Overall, the methodology of injection-molding a magnesium-based alloy into an aluminum alloy casing and the further forming and deposition of passivation and protective layers, respectively on the injection-moided metal casing, followed by chamfering, anodizing, and sealing the anodic layer according to the present subject matter, is simple, less time consuming and less resource consuming, and cost efficient. Further, the device covers thus obtained are aesthetically appealing, light in weight, while also being chemico-mecbanically stable. [0028] The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the following description to refer to the same or similar parts. While several examples are described in the description, modifications, adaptations, and other implementations are possible. Accordingly, the following detailed description does not limit the disclosed examples, instead, the proper scope of the disclosed examples may be defined by the appended claims.

[0029] Fig . 1 illustrates a method for forming a glossy casing for an electronic device 100, according to an example of the present disclosure. The at least one magnesium-based alloy may be injection-molded into an aluminum alloy casing, injection molding 102 may be carried out at a temperature of from about 200 X to about 500 X. in an example, the injection-molding may be carried out at a temperature of from about 250 X to about 450 X. in another example, the injection-molding may be carried out at a temperature of from about 250 X to about 400 X. in yet another example, the injection-molding may be carried out at a temperature of from about 300 X to about 400 X.

[0030] in an example, the at least one magnesium-based alloy may be thixo- moided into the aluminum alloy casing. In another example, the magnesium- based alloy may be die-casted into the aluminum alioy casing.

[0031] The injection-molding 102 may be carried out on a section or the whole surface of the aluminum alloy casing. In an example, the injection molding may be carried out an injection pressure of from about 50 MPa to about 150 MPa. The injection speed may be of from about 40 rμm to about 200 rμm and the mold temperature may be of from about 200 X to about 500 X,

[0032] In an example, at least one magnesium-based alloy may be injection- molded into two surfaces of the aluminum alloy casing. In another example, the at least one magnesium-based alloy may be injection-molded wholly on within the cavity in the aluminum alloy casing, wherein the magnesium-based alloy is in contact with the first surface or with the second surface within the aluminum alioy casing, in case of the magnesium-based alioy being injection-molded into a section of the surface, the at least one magnesium-based alloy may be injection- molded into at least 10% of a cavity in the aluminum alloy casing, in another example, the at least one magnesium-based alloy may be injection-molded into at least 20% of a cavity in the aluminum alloy casing. In yet another example, the at least one magnesium-based alloy may be injection-molded into at least 65% of a cavity in the aluminum alloy substrate casing.

[0033] I n an example, the injection-molding may be carried out by combining the magnesium-based alloys, such as AZ63, AZ81, AZ91, AM50, AM6Q, AZ31, AZ61 , AZ80, AE44, AJ62A, ALZ391 , AMCa802, LZ91. The mixture obtained from the aforementioned combination may be poured into the aluminum alloy casing at a temperature of from about 200 °C to about 500 X, The molten mixture of magnesium-based alloy in the mold may be allowed to cool and solidify. The casing comprising the injectionmolded magnesium-based alloy may be cleaned, dried, washed, polished, degreased, and activated. The cleaning and washing may be performed using a buffer solution, which may help in removing foreign particles, if any, present on the surface of the casing. Further, the casing may be chemically polished using abrasives to remove irregularities that may be present on the surface of the casing. The casing may also be degreased through ultrasonic degreasing methods to remove impurities, such as fat, grease, or oil from the surface of the casing. Further, the casing may also be activated through acid treatment for removing the natural oxide layer, if any, present on the surface of the casing.

[0034] The casing may be of a thickness of from about 0.3 mm to about 2,0 mm. In an example, the casing may have a thickness of from about 0,4 mm to about 1.9 mm. in another example, the casing may have a thickness of from about 0.5 mm to about 1.8 mm. In yet another example, the casing may have a thickness of about 0.7 mm.

[0035] As can be seen from Fig. 1, the at least one portion of the casing is then chamfered. The method for forming a glossy casing for an electronic device 100, comprises chamfering at feast a portion of the aluminum alloy casing 104, In an example, the chamfering 104 may be carried out at portions, such as cover edge, touch pad, fingerprint scanner, click pad, side wall, logo, among others. The chamfered portions of the casing as mentioned may have defects, and in order to eliminate the defects and give the edges of the portions a more even surface with improved strength, they may be chamfered. The chamfering involves abrasive removal of edge material that can give it the desired finishing and also shape its form, in an example, chamfering may be carried out by a CNC diamond cutting machine, in another example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 5000 to about 90000 rμm for a period in a range of from about 3 to about 8 minutes. In yet another example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 6000 to about 80000 rμm .

[0036] The chamfered casing may be cleaned, degreased, washed and dried, prior to anodizing, 106. in an example, the cleaning may be carried out in the presence of at least one aqueous alkaline compound, such as sodium hydroxide. The degreasing may be carried out by ultrasonic degreasing methods to remove impurities, such as fat, grease, or oil from the surface of the chamfered casing.

[0037] Further, the chamfered portions may be anodized to obtain an anodized substrate, s.e, comprising an anodic iayer over the chamfered portion. Forming anodic layers protects and cosmetically enhances metal surfaces. Anodizing on a chamfered portion of the casing aiso permits an underlying metal surface to be viewable. For instance, chamfering the metal casing may form features in the casing for employing patterns and logos on the metal casing. Electronic devices after chamfering tend to have sharp corners and edges that make it difficult to form a consistent and cosmetically appealing anodization film thereon. The method of anodization as described herein may in addition to protection, aiso cosmetically enhance the look and feel of metal surfaces of electronic devices. The anodic layer may be transparent in order to reveal features of the underlying metal surface. The underlying metal surface may have a reflective shine or ornamental features which would be viewable through the transparent anodic layer.

[0038] At block 106, of Fig. 1 , anodizing a chamfered portion of the casing may be carried out in presence of 150-200 g/L of at feast one acid at a potential of from about 5 to about 20 V for a period of from about 20 to about 50 minutes at a temperature of from about 10 X to about 50°C. in an example, anodizing a chamfered! portion of the casing 106 may be carried out in presence of 150-200 g/L of at Seast one acid at a potential of from about 10 to about 20 V for a period of from about 22 to about 40 minutes at a temperature of from about 15 °C to about 50*0. In another example, anodizing a chamfered portion of the casing 106 may be carried out in presence of 150-200 g/L of at Seast one acid at a potential of from about 10 to about 18 V for a period of from about 25 to about 40 minutes at a bath temperature of from about 15 °C to about 45°C. The at feast one acid may be seiected from hydrochioric acid, nitric acid, sulfuric acid, phosphoric acid, or combinations thereof,

[0039] f n an example, the anodizing on a chamfered portion, 106, may result in the deposition of the anodic layer having a thickness of from about 3.0 μm to about 12.0 μm, in another example, the anodic layer may have a thickness of from about 5,0 μm to about 12,0 μm. in yet another example, the anodic layer may have a thickness of from about 7.0 μm to about 12.0 μm, in another example, the anodic layer may have a thickness of about 10 μm. The thickness of the anodic layer achieved may be directly related to the potential applied and time employed in the process of anodization.

[0040] Fig. 1 shows that depositing a seating layer 108 may be done on the anodized substrate to obtain a casing for an electronic device. Subsequent to sealing it may be baked, in an example, the seaiing may be carried out in the presence of a compound selected from aluminum fluoride, nickel fluoride, cerium fluoride, cerium acetate, aluminum acetate, nickel acetate, or combinations thereof. In another example, the sealing may be carried out in the presence of aluminum fluoride, in yet another example, the seaiing may be carried out in the presence of nickei fluoride. In an example, the compound may be utilized in the form of an aqueous dispersion further comprising a surfactant having a strength of about 0.1 % to about 2.0 % with respect to the dispersion. The process of baking post seaiing may be carried out at a temperature in the range of from about 60 ^º C to about 90º C for a period in the range of about 15 seconds to about 180 seconds, in an example, the baking may be carried out at a temperature in the range of from about 62 °C to about 88 °C for a period in the range of about 30 seconds to about 60 seconds. In another example, the baking may be carried out at a temperature of 70 °€ for a period of 45 seconds, !n an example, the sealing layer thus obtained may have a thickness of about 1.0 μm to about 3.0 μm. in another example, the seating layer may have a thickness of about 1.2 μm to about 2.8 μm.

[0041] In an example, the method for forming casing 100 may reveal an enhanced gloss value of from about 80 to about 95 units as measured by American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 80°. in another example, the method 100 may reveal a gloss value of from about 82 to about 93 units, in yet another example, the method 100, may reveal to a gloss value of about 92 units.

[0042] A method for forming an enclosure for an electronic device is aiso discussed. Fig. 2 shows a flow chart Illustrating details of a method for forming an enclosure for an electronic device 200, according to an example of the present disclosure. The method for forming an enclosure for an electronic device comprises injecting at least one metal alloy into a cavity in a metal frame, 202. The at least one metal alloy is a magnesium-based alloy and may be selected from AZ63, AZ81, AZ91 , AM 50, AIVS80, AZ31, AZ61, AZS0, AE44, AJ62A, ALZ391, AMCa602, LZ91, or combinations thereof. The metal frame Is an aluminum alloy frame which may be selected from AL575, AL1050, AL1G80, AL1100, All 199, AL2014, AL2024, AL2219, AL3004, AL4041, AL5005, AL5010, ALS019, AL5Q24, AL5026, AL5C50, AL5052, AL5056, AL5059, AL5083, AL5086, AL5154, AL5182, ALS252, AL5254, AL5356, A L 5454, AL5456, AL5457, AL5557, AL5852, AL5657, AL5754, AL6005, AL6005A, AL6060, AL6061, AL6063, AL6066, AL6D7Q, AL8082, AL6105, AL6151, AL8162, ALS205, AL6282, AL6351, AL6463, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079, AL7116, AL7129, AL7175, AL7475, AL7178, or combinations thereof.

[0043] In an example, the injecting the at least one metal alloy into a cavity in a metal frame, i.e., injecting magnesium-based alloy into an aluminum alloy based frame may be carried out by Injection molding the magnesium-based alloy into a cavity of an aluminum alloy frame or the magnesium-based alloy may be die-casted into a cavity of an aluminum alloy frame. In an example, the injection molding may be carried out at an Injection pressure of from about 50 MPa to about 150 MPa. The injection speed may be of from about 40 rμm to about 200 rμm and the mold temperature may be from about 200 X to about 500 X. in an example, the Injection-moidsng may be carried out at a temperature of from about 250 X to about 450 °C. In another example, the injection-molding may be carried out at a temperature of from about 250 X to about 400 °C. In yet another example, the injection-molding may be carried out at a temperature of from about 300 X to about 400 X.

[0044] in an example, magnesium-based alloy may be injection-molded Into at least 10% of a cavity in the aluminum alloy frame. In another example, the at least one magnesium-based ailoy may be injection-molded into at least 20% of a cavity in the aluminum alloy frame, in yet another example, the at least one magnesium-based alloy may be injection-molded into at least 85% of a cavity in the aluminum alloy frame, in an example, injecting at least one metal alloy into a cavity in a metal frame provides a frame having a tensile strength of from about 200 MPa to about 700 MPa as measured by American Society for Testing and Materials (ASTM) D790. In another example, injecting at least one metal alloy into a cavity in a metai frame provides a frame having a tensile strength of from about 250 MPa to about 600 MPa as measured by American Society for Testing and Materials (ASTM) D790. in yet another example, injecting at least one metal alloy into a cavity in a metai frame provides a frame having a tensile strength of from about 350 MPa to about 800 MPa as measured by American Society for Testing and Materials (ASTM) D790.

[0045] In an example, the aluminum alloy-based frame may be prefabricated into a suitable format, i.e., with a cavity, by known processes. The injection-molding of magnesium-based alloy may be carried out into a cavity of the aluminum alloy-based frame. Injecting magnesium-based alloy into the aiuminum alloy-based frame may result in a frame having a thickness of from about 0,3 mm to about 2,0 mm.

[0046] Fig, 2 additionally includes the deposition of a passivation layer on to at least one side of the metal frame to obtain a passivated metal frame. The passivated metal frame may be obtained by depositing a passivation iayer on to at least one side of the metal frame 204 by a process selected from degreasing, cleaning, polishing, neutralizing, chemical passivation treatment, electrochemical passivation treatment or combinations thereof.

[0047] In an example, depositing the passivation layer may be carried out by electro-chemical passivation treatment. The electro-chemical passivation treatment is a micro-arc oxidation process which may be carried out at a voltage of from about 150 V to about 550 V at a temperature of from about 10 °C to about 45 ^' C for a period of from about 2 minutes to about 25 minutes. In another example, the deposition of the passivation layer may be carried out by micro-arc oxidation carried out at a voitage of from about 250 V to about 450 V at a temperature of from about 12 °C to about 42 C for a period of from about 5 minutes to about 22 minutes. In an example, the passivation layer formed by micro-arc oxidation may have a thickness of from about 1 μm to about 15 μm. In another example, the passivation layer formed by micro-arc oxidation may have a thickness of from about 3 μm to about 12 μm. In yet another example, the passivation layer formed by micro-arc oxidation may have a thickness of from about 3 μm to about 7 μm.

[0048] 1 n an example, depositing the passivation layer on to at least one side of the metal frame carried out by electro-chemical passivation treatment may be carried out in the presence of at least one chemical selected from sodium silicate, metal phosphates, potassium fluoride, potassium hydroxide, sodium hydroxide, fiuoro-zirconates, sodium hexametaphosphate, sodium fluoride, ferric ammonium oxalate, phosphoric acid salt, graphite powder, silicon dioxide powder, a!uminum oxide powder, and combinations thereof. In an example, the chemical may be employed at a dosage of from about 0.05% to about 15% in the presence of water at a pH of from about 9.0 to about 13. In another example, the chemical may be employed at a dosage of from about 0,1% to about 12% in the presence of water at a pH of from about 9.0 to about 12.0. In an example, the passivated metal frame may have a first surface and second surface. The first surface may be towards the outer side of the passivated metal frame or maybe towards the inner side of the passivated metal frame. Similarly, the second surface may be towards the outer side of the passivated metal frame or maybe towards the Inner side of the passivated metal frame. [0049] In an example, depositing a passivation layer on to at least one side of the metal frame, 204 may be carried out by a process of dip coating for a period of from about 20 seconds to about 120 seconds. In an example, depositing a passivation layer on to at least one side of the metal frame, 204 may be carried out by a process of dip coating for a period of from about 30 seconds to about 120 seconds. In an example, the passivation layer obtained by the process of dip coating may have a thickness of from about 1 μm to about 5 μm. In another example, the passivation layer obtained by the process of dip coating may have a thickness of from about 1,5 μm to about 3.0 μm,

[0050] in an example, the dip coating may be carried out in the presence of at least one salt of manganese, molybdates, vanadate, phosphate, chromate, stannate, and combinations thereof. In an example, the at least one salt may be manganese. In an example, the salt may be dispersed in the form of an aqueous solution having a concentration of from about 3% to about 15% based on total weight of the aqueous solution. In another example, the salt may be dispersed in the form of an aqueous solution having a concentration of from about 5% to about 12% based on total weight of the aqueous solution,

[0051] The passivated metal frame may be coated with at least one protective layer to obtain a coated metal frame, Fig. 2 shows the method for forming an enclosure for an electronic device. The method comprises coating at least one protective layer on to the passivated metal frame, 206. The protective layer may be coated on to the passivation layer to obtain a coated metal frame. In an example, the coating of the protective layer may be carried out by spray coating.

[0052] In an example, the protective layer may have a thickness in a range of from about 5.0 μm to about 70.0 μm. In another example, the protective layer may have a thickness in a range of from about 10.0 μm to about 68,0 μm. In yet another example, the protective layer may have a thickness In a range of from about 10.0 μm to about 65.0 μm.

[0053] The coating of at least one protective layer on to the passi vated metal frame, 206, carried out by spray coating may be carried out in a manner, whereby the protective layer thus formed may comprise multiple layers, such as primer, base coat, and top coat, in an example, the spray-coated protective layer comprises sequentially deposited coats of primer coat having a thickness of from about 5.0 μm to about 20.0 μm, followed by base coat having a thickness of from about 10.0 μm to about 20.0 μm, followed by top coat having a thickness of from about 10.0 μm to about 25.0 μm.

[0054] The passivation layer may be cleaned, dried, degreased and washed prior to the coating of the protective layer. The protective layer may comprise primer, either alone or in combination with additional layers. The primer may also be applied as single or multiple coats to achieve the desired thickness and finish. In an example, the primer may have a thickness of from about 5.0 μm to about 20.0 μm. In another example, the primer may have a thickness of from about 8.0 μm to about 18,0 μm. In yet another example, the primer may have a thickness of about 12.0 μm.

[0055] In an example, the primer may be coated on the metai frame or the passivated metai frame by spray coating polyurethanes followed by heat treatment at a temperature of from about 60 X to about 80 °c for a period in a range of from about 15 to about 40 minutes, in another example, the primer may be coated by spray coating polyurethane followed by heat treatment at a temperature of from about 82 X to about 78 °C for a period in a range of from about 18 to about 38 minutes. In yet another example, the primer may be coated by spray coating thermoplastics, such as polyurethanes followed by heat treatment at a temperature of about 70 °C for a period of about 25 minutes. [0056] The protective layer may comprise a base coat, in combination with additional Sayers. The base coat may also be applied as single or multiple coats to achieve the desired thickness and finish. In an exampie, the base coat may have a thickness of from about 10.0 μm to about 20.0 μm, in another example, the base coat may have a thickness of from about 12.0 μm to about 18.0 μm. In yet another exampie, the base coat may have a thickness of about 15.0 μm. In an example, the base coat may be a polyurethane containing pigments selected from carbon black, titanium dioxide, clay, mica, talc, barium sulfate, calcium carbonate, aluminum powder, plastic bead, dyes, and combinations thereof, in an exampie, the spray-coated base coat comprises polyurethane containing carbon black. In another example, the spray-coated base coat comprises polyurethane containing titanium dioxide, in yet another example, the spray- coated base coat comprises polyurethane containing day.

[0057] In another example, the base coat coated by spray coating may be followed by heat treatment at a temperature of from about 60 °C to about 80 °C for a period in a range of from about 15 to about 40 minutes, in another example, the base coat coated by spray coating may be followed by heat treatment at a temperature of from about 62 °C to about 78 °C for a period in a range of from about 18 to about 38 minutes. In yet another example, the base coat coated by spray coating may be followed by heat treatment at a temperature of about 70 °C for a period of about 25 minutes.

[0058] The protective layer may comprise top coat, in combination with additions! layers. The top coat may also be applied as single or multiple coats to achieve the desired thickness and finish, in an example, the top coat may be coated on the first surface of the passivated metal frame, in another example, the top coat may be coated on the second surface of the passivated metal frame. [0059] In an example, the top coat may have a thickness of from about 10.0 μm to about 25.0 μm. In another example, the top coat may have a thickness of from about 12,0 μm to about 22,0 μm. In yet another example, the top coat may have a thickness of about 17.0 μm.

[0080] In an example, the top coat may be made of poSyacrylic acid, polyurethane, urethane acrylates, acrylic acrylates, epoxy acrylates, or combinations thereof. In another example, the top coat may be made of polyacryiic acid. In yet another example, the top coat may be made of polyurethane. In some examples, the top coat may be made of urethane acrylates.

[0061] In an example, the top coat coated by spray coating may be followed by UV treatment in a range of from about 700 mJ/cm ² to about 1200 mJ/cm ² for a period in a range of from about 10 seconds to about 30 seconds. In another example, the top coat coated by spray coating may be followed by UV treatment in a range of from about 800 mJ/cm ² to about 1100 mJ/cm ² for a period in a range of from about 15 seconds to about 25 seconds, in yet another example, the top coat coated by spray coating may be followed by UV treatment of about 950 rnJ/cm ² for a period of about 20 seconds.

[0062] In some examples, the top coat coated by spray coating a polyurethane may be followed by heat treatment at a temperature of from about 60 °C to about 80 X for period in a range of from about 15 to about 40 minutes, !n another example, the top coat coated by spray coating may be followed by heat treatment at a temperature of from about 62º C to about 78 ºC for a period in a range of from about 18 to about 38 minutes, in yet another example, the top coat coated by spray coating may be followed by heat treatment at a temperature of about 70 °C for a period of about 25 minutes.

[0063] In an example, coating the protective layer may be carried out subsequent to depositing a passivation layer to introduce colors and to provide aesthetically improved finish prior to chamfering. The method for forming an enclosure for an electronic device 200, comprises chamfering at least a portion of coated metal frame, 208 to obtain a glossy chamfered metal frame.

[0064] As can be seen from Fig. 2, the at least a portion of the coated metal frame is chamfered, in an example, the chamfering 208 may be carried out at portions such as cover edge, touch pad, fingerprint scanner, click pad, side wail, logo, among others to obtain glossy chamfered metai frame. The chamfering involves abrasive removal of edge material that can give it the desired finishing and also shape its form, in an example, chamfering may be carried out by a CMC diamond cutting machine. In another example, the chamfering may be carried out with a CMC diamond cutting machine at speed of from about 5000 to about 90000 rμm for a period in a range of from about 3 to about 8 minutes, in yet another example, the chamfering may be carried out with a CMC diamond cutting machine at speed of from about 6000 to about 80000 rμm,

[0065] The chamfered metai frame may be cleaned, degreased, washed and dried, prior to anodizing, 210, to obtain anodized substrate, in an example, the cleaning may be carried out in the presence of at least one aqueous alkaline compound such as sodium hydroxide. In another example, the degreasing may be carried out by ultrasonic degreasing methods to remove impurities, such as fat, grease, or oil from the surface of the chamfered metai frame. [0088] Further, the chamfered portions of the coated metal frame may be anodized to obtain an anodized substrate, i.e, comprising an anodic layer over the chamfered portion. Forming anodic layers protect and cosmetically enhance metal surfaces are described. Anodizing on a chamfered portion of the glossy chamfered metal frame, 210, permits an underlying metal surface to be viewable. For Instance, the coated metal frame after chamfering may form features in the metal and design operations to form paterns and logos on the metal surfaces. Electronic devices tend to have sharp comers and edges that make it difficult to form a consistent and cosmetically appealing anodization film thereon. The method of anodization as described herein may in addition to protection .also cosmetically enhance the look and feel of metai surfaces of electronic devices. The anodic layer formed after the anodizing of the giossy chamfered metal frame may be transparent in order to reveal features of the underlying metai surface. The underlying metai surface may have a reflective shine or ornamental features which would be viewable through the transparent anodic layer.

[0067] Fig. 2 shows that anodizing a portion of the glossy chamfered metal frame 210 may be carried out in presence of 150-200 g/L of at least one acid at a potential of from about 5 to about 20 V for a period of from about 20 to about 50 minutes at a temperature of from about 10 X to about 50“C. In an example, anodizing a chamfered portion of the metal frame 210 may be carried out in presence of 150-200 g/L of at least one acid at a potential of from about 10 to about 20 V for a period of from about 22 to about 40 minutes at a temperature of from about 15 °C to about 50°C. In another example, anodizing a chamfered portion of the metal frame 210 may be carried out in presence of 150-200 g/L of at least one acid at a potential of from about 10 to about 18 V for a period of from about 25 to about 40 minutes at a bath temperature of from about 15 *C to about 45°c. The at least one acid may be selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, or combinations thereof.

[0088] In an example, the anodizing on a chamfered portion, 210, may result in the deposition of the anodic layer having a thickness of from about 3.0 μm to about 12.0 μm. In another example, the anodic layer may have a thickness of from about 5.0 μm to about 12.0 μm. In yet another example, the anodic layer may have a thickness of from about 7.0 μm to about 12.0 μm. in another example, the anodic layer may have a thickness of about 10 μm. The thickness of the anodic layer achieved may be directly related to the potential applied and time employed in the process of anodization.

[0069] Fig. 3 illustrates a method of forming an enclosure 300 for an electronic device, according to another example of the present disclosure. The flow chart shown in Fig. 3, shows a method for forming an enclosure that comprises injecting at least one metal alloy into a cavity in a metal frame, 302, followed by depositing a passivation iayer on to at ieast one side of the metal frame, 304, to obtain a passivated metal frame. The passivated metal frame is then coated with at Ieast one protective layer, 306, to obtain a coated metal frame, it further includes chamfering at Ieast a portion of the coated metal frame, 306, to obtain a glossy chamfered metal frame followed by anodizing a portion of the glossy chamfered metal frame, 310, prior to sealing and baking the anodized portion, 312, to form an enclosure for an electronic device.

[0070] The method for forming an enclosure for an electronic device comprises injecting at least one metal alloy into a cavity in a metal frame, 302. The at ieast one metal alloy is a magnesium-based alloy and may be selected from AZ63, AZ81, AZ91 , AM50, AM80, AZ31, AZ61, AZ80, AE44, AJ62A, ALZ391, AMCaS02, LZ91, or combinations thereof. The metal frame is an aluminum alloy frame which may be selected from AL575, All 050, AL1060, AL1100, AL1199, AL2014, AL2024, AL2219, AL3004, AL4041, AL5005, AL5010, AL5019, AL5024, AL5026, AL5050, AL5052, AL5056, AL5059, AL5083, AL5086, AL5154, AL5182, AL5252, AL5254, AL5356, AL5454, AL5456, AL5457, AL5557, AL5652, AL5657, AL5754, AL60Q5, AL6005A, AL6060, AL6061, AL6083, AL6066, AL6070, AL6082, AL6105, AL6151, AL6162, AL6205, AL6262, AL6351, AL6463, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079, AL7116, AL7129, AL7175, AL7475, AL7178, or combinations thereof.

[0071] In an example, the injecting the at Ieast one metal alloy into a cavity in a metal frame 302, i.e, injecting magnesium-based ai!oy into an aluminum alloy based frame may be carried out by injection molding the magnesium-based alloy into a cavity of an aluminum alloy frame or the magnesium-based alloy may be die-casted into a cavity of an aluminum alloy frame. In an example, the injection molding may he carried out an injection pressure of from: about 50 MPa to about 150 MPa. The injection speed may be from about 40 rμm to about 200 rμm and the mold temperature may be from about 200 X to about 500 X, In an example, the injection-molding may be carried out at a temperature of from about 250 X to about 450 X, In another example, the injection-molding may be carried out at a temperature of from about 250 X to about 400 X. In yet another example, the injection-molding may be carried out at a temperature of from about 300 X to about 400 X.

[0072] In an example, magnesium-based alloy may be injection -moided into at least 10% of a surface of the aluminum alloy frame. In another example, the at feast one magnesium-based alloy may be injection-molded into at least 20% of a surface of the aluminum alloy frame. In yet another example, the at least one magnesium-based alloy may be injection-molded into at least 65% of a surface of the aluminum alloy frame, in an example, injecting at least one metal alloy info a cavity in a metal frame provides a frame having a tensile strength of from about 200 MPa to about 700 MPa as measured by American Society for Testing and Materials (ASTM) D790. in another example, injecting at least one metal alloy into a cavity in a metal frame provides a frame having a tensile strength of from about 250 MPa to about 800 MPa as measured by American Society for Testing and Materials (ASTM) D790. in yet another example, injecting at least one metal alloy into a cavity in a metal frame provides a frame having a tensile strength of from about 350 MPa to about 600 MPa as measured by American Society for Testing and Materials (ASTM) D790.

[0073] In an example, the aluminum ai!oy-based frame may be prefabricated into a suitable format, i.e, with a cavity, by known processes. The injection-molding of magnesium-based alloy may be carried out into a cavity of the aluminum alioy-based frame. Injecting magnesium-based alloy into the aluminum alioy-based frame may result in a frame having a thickness of from about 0.3 mm to about 2.0 mm,

[0074] Fig. 3, additionally includes the deposition of a passivation layer on to at least one side of the metal frame to obtain a passivated metal frame. The passivated meta! frame may be obtained by depositing a passivation layer on to at least one side of the metai frame 304 by a process selected from degreasing, cleaning, polishing, neutralizing, chemical passivation treatment, electrochemical passivation treatment or combinations thereof.

[0075] In an example, depositing the passivation layer may be carried out by electro-chemical passivation treatment. The electro-chemical passivation treatment is a micro-arc oxidation process which may be carried out at a voltage of from about 150 V to about 550 V at a temperature of from about 10 °C to about 45°C for a period of from about 2 minutes to about 25 minutes, in another example, the deposition of the passivation layer may be carried out by micro-arc oxidation carried out at a voltage of from about 250 V to about 450 V at a temperature of from about 12 °C to about 42°C for a period of from about 5 minutes to about 22 minutes. In an example, the passivation layer formed by micro-arc oxidation may have a thickness of from about 2 μm to about 15 μm. In another example, the passivation Iayer formed by micro-arc oxidation may have a thickness of from about 3 μm to about 12 μm. In yet another example, the passivation layer formed by micro-arc oxidation may have a thickness of from about 3 μm to about 7 μm.

[0076] I n an example, depositing the passivation layer on to at least one side of the metal frame carried out by electro-chemical passivation treatment may be carried out in the presence of at least one chemical selected from sodium silicate, metal phosphates, potassium fluoride, potassium hydroxide, sodium hydroxide, fiuoro-zirconates, sodium hexametaphosphate, sodium fluoride, ferric ammonium oxalate, phosphoric acid salt, graphite powder, silicon dioxide powder, aluminum oxide powder, and combinations thereof. In an example, the chemical may be employed at a dosage of from about 0,05% to about 15% in the presence of water at a pH of from about q to about 13. In another example, the chemical may be employed at a dosage of from about 0.1% to about 12% in the presence of water at a pH of from about 9.0 to about 12.0. In an example, the passivated metal frame may have a first surface and second surface. The first surface may be towards the outer side of the passivated metal frame or maybe towards the inner side of the passivated metai frame. Similarly, the second surface may be towards the outer side of the passivated metal frame or maybe towards the inner side of the passivated metal frame.

[0077] In an example, depositing a passivation layer on to at least one side of the metal frame, 304 may be carried out by a process of dip coating for a period of from about 20 seconds to about 120 seconds. In an example, depositing a passivation layer on to at least one side of the metal frame, 304 may be carried out by a process of dip coating for a period of from about 30 seconds to about 120 seconds. In an example, the passivation layer obtained by the process of dip coating may have a thickness of from about 1 μm to about 5 μm. In another example, the passivation layer obtained by the process of dip coating may have a thickness of from about 1.5 μm to about 3.0 μm.

[0078] In an example, the dip coating may be carried out in the presence of at least one salt of manganese, molybdates, vanadate, phosphate, chromate, stannate, and combinations thereof, in an example, the at least one salt may be manganese. In an example, the salt may be dispersed in the form of an aqueous solution having a concentration of from about 3% to about 15% based on total weight of the aqueous solution. In another example, the salt may be dispersed in the form of an aqueous solution having a concentration of from about 5% to about 12% based on total weight of the aqueous solution,

[0079] The passivated metal frame may be coated with at least one protective layer to obtain a coated metal frame. Fig. 3 shows the method for forming an enclosure for an electronic device. The method comprises coating at least one protective layer on to the passivated metal frame, 306. The protective layer may be deposited on to the passivation layer to obtain a coated metal frame. In an example, the coating of the protective layer may be carried out by spray coating.

[0080] In an example, the protective layer may have a thickness in a range of from about 5.0 μm to about 70.0 μm. In another example, the protective layer may have a thickness in a range of from about 10.0 μm to about 68.0 μm. In yet another example, the protective layer may have a thickness in a range of from about 10.0 μm to about 65.0 μm. [0081] The coating at least one protective layer on to the passivated metal frame, 306, carried out by spray coating may be carried out in a manner, whereby the protective Iayer thus formed may comprise multipie Sayers, such as primer, base coat, and top coat, in an example, the spray-coated protective layer comprises sequentially deposited coats of primer coat having a thickness of from about 5,0 μm to about 20.0 μm, followed by base coat having a thickness of from about 10.0 μm to about 20,0 μm, followed by top coat having a thickness of from about 10,0 μm to about 25,0 μm,

[0082] The passivation Iayer may be cleaned, dried, degreased and washed prior to coating of the protective layer. The protective layer may comprise primer, either alone or in combination with additional layers. The primer may also be applied as single or multiple coats to achieve the desired thickness and finish. In an example, the primer may have a thickness of from about 5,0 μm to about 20.0 μm. in another example, the primer may have a thickness of from about 8.0 μm to about 18.0 μm, in yet another example, the primer may have a thickness of about 12.0 μm.

[0083] In an example, the primer may be coated on the metal frame or the passivated metai frame by spray coating polyurethanes followed by heat treatment at a temperature of from about 60 “C to about 80 X for a period in a range of from about 15 to about 40 minutes. In another example, the primer may be coated by spray coating polyurethane followed by heat treatment at a temperature of from about 62 °C to about 78 X for a period in a range of from about 18 to about 38 minutes. In yet another example, the primer may be coated by spray coating thermoplastics, such as polyurethanes followed by heat treatment at a temperature of about 70 X for a period of about 25 minutes.

[0084] The protective layer may comprise a base coat, in combination with additional layers. The base coat may also be applied as a single or multiple coats to achieve the desired thickness and finish, in an example, the base coat may have a thickness of from about 10.0 μm to about 20,0 μm. in another example, the base coat may have a thickness of from about 12,0 μm to about 18.0 μm. In yet another example, the base coat may have a thickness of about 15.0 μm. in an example, the base coat may be a polyurethane containing pigments selected from carbon black, titanium dioxide, clay, mica, talc, barium sulfate, calcium carbonate, aluminum powder, plastic bead, dyes, and combinations thereof. In an example, the spray-coated base coat comprises polyurethane containing carbon black. In another example, the spray-coated base coat comprises polyurethane containing titanium dioxide. In yet another example, the spray- coated base coat comprises polyurethane containing clay.

[0085] In another example, the base coat coated by spray coating may be followed by heat treatment at a temperature of from about 80 °Cto about 80 °C for a period in a range of from about 15 to about 40 minutes. In another example, the base coat coated by spray coating may be followed by heat treatment at a temperature of from about 62 “C to about 78 °C for a period in a range of from about 18 to about 38 minutes, in yet another example, the base coat coated by spray coating may be foilowed by heat treatment at a temperature of about 70 °C for a period of about 25 minutes.

[0088] The protective layer may comprise top coat, in combination with additional layers. The top coat may also be applied as single or multiple coats to achieve the desired thickness and finish. In an example, the top coat may be coated on the first surface of the passivated metal frame. In another example, the top coat may be coated on the second surface of the passivated metal frame. [0087] in an example, the top coat may have a thickness of from about 10.0 μm to about 25.0 μm. In another example, the top coat may have a thickness of from about 12.0 μm to about 22.0 μm. In yet another example, the top coat may have a thickness of about 17.0 μm.

[0088] In an example, the top coat may be made of poSyacrylic acid, polyurethane, urethane acrylates, acrylic acrylates, epoxy acrylates, or combinations thereof. In another example, the top coat may be made of po!yacrySic acid. In yet another example, the top coat may be made of polyurethane, in some examples, the top coat may be made of urethane acrylates.

[0089] In an example, the top coat coated by spray coating may be followed by UV treatment in a range of from about 700 mJ/cm ² to about 1200 mJ/cm ² for a period in a range of from about 10 seconds to about 30 seconds. In another example, the top coat coated by spray coating may be followed by UV treatment in a range of from about 800 mJ/cm ² to about 1100 mj/cm ² for a period in a range of from about 15 seconds to about 25 seconds. Sn yet another example, the top coat coated by spray coating may be followed by UV treatment of about 950 mj/cm ² for a period of about 20 seconds.

[0090] In some examples, the top coat coated by spray coating a polyurethane may be followed by heat treatment at a temperature of from about 80 °C to about 80 X for a period in a range of from about 15 to about 40 minutes, in another example, the top coat coated by spray coating may be followed by heat treatment at a temperature of from about 82 °C to about 78 X for a period in a range of from about 18 to about 38 minutes. In yet another example, the top coat coated by spray coating may be followed by heat treatment at a temperature of about 70 X for a period of about 25 minutes.

[0091] In an example, coating the protective layer may be carried out subsequent to depositing a passivation layer to introduce colors and to provide aesthetically improved finish prior to chamfering. The method for forming an enclosure for an electronic device 300, comprises chamfering at least a portion of the coated metal frame, 308 to obtain a glossy chamfered metal frame.

[0092] As can be seen from Fig. 3, the at least a portion of the coated metal frame is chamfered, in an example, the chamfering 308 may be carried out at portions such as cover edge, touch pad, fingerprint scanner, click pad, side wail, logo, among others to obtain glossy chamfered metal frame. The chamfering involves abrasive remove! of edge materiaI that can give it the desired finishing and also shape its form. In an example, chamfering may be carried out by a CMC diamond cutting machine. In another example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 5000 to about 90000 rμm for a period in a range of from about 3 to about 8 minutes. In yet another example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 6000 to about 80000 rpm.

[0093] The chamfered metal frame may be cleaned, degreased, washed and dried, prior to anodizing, 310, to obtain anodized substrate. In an example, the cleaning may be carried out in the presence of at least one aqueous alkaline compound such as sodium hydroxide, in another example, the degreasing may be carried out by ultrasonic degreasing methods to remove impurities, such as fat, grease, or oil from the surface of the chamfered metal frame,

[0094] Further, the chamfered portions of the coated metal frame may be anodized to obtain an anodized substrate, i.e, comprising an anodic layer over the chamfered portion. Forming anodic layers protect and cosmetically enhance metal surfaces are described. Anodizing on a chamfered portion of the glossy chamfered metal frame, 310, permits an underlying metal surface to be viewable. For instance, the coated metal frame after chamfering may form features in the metal and design operations to form patterns and logos on the metal surfaces. Electronic devices tend to have sharp comers and edges that make it difficult to form a consistent and cosmetically appealing anodization film thereon. The method of anodization as described herein may in addition to protection, also cosmetically enhance the look and feel of metal surfaces of electronic devices. The anodic layer formed after the anodizing of the glossy chamfered mefal frame may be transparent in order to reveal features of the underlying metal surface. The underlying metal surface may have a reflective shine or ornamental features which would be viewable through the transparent anodic layer.

[0095] Fig. 3 includes anodizing a portion of the g!ossy chamfered mefal frame 310. The anodizing may be carried out in presence of 150-200 g/L of at least one acid at a potential of from about 5 to about 20 V for a period of from about 20 to about 50 minutes at a temperature of from about 10 X to about 50°C. In an example, anodizing a chamfered portion of the metal frame 310 may be carried out in presence of 150-200 g/L of at least one add at a potential of from about 10 to about 20 V for a period of from about 22 to about 40 minutes at a temperature of from about 15 X to about 50°C. In another example, anodizing a chamfered portion of the metal frame 310 may be carried out in presence of 150- 200 g/L of at least one acid at a potential of from about 10 to about 18 V for a period of from about 25 to about 40 minutes at a bath temperature of from about 15 °C to about 45°C. The at least one acid may be selected from hydrochloric acid, nitric acid, suifuric acid, phosphoric acid, or combinations thereof. [0098] In an example, the anodizing on a chamfered portion, 310, may result in the deposition of the anodic layer having a thickness of from about 3,0 μm to about 12,0 μm. in another example, the anodic layer may have a thickness of from about 5.0 μm to about 12.0 μm. In yet another example, the anodic layer may have a thickness of from about 7,0 μm to about 12.0 μm . In another example, the anodic layer may have a thickness of about 10 μm. The thickness of the anodic layer achieved may be directly related to the potential applied and time employed in the process of anodization.

[0097] The anodization process further includes sealing the anodic layer followed by baking to obtain an anodic layer, thus obtained anodic layer may have a thickness of about 3.0 μm to about 12.0 μm. Fig. 3 illustrated the sealing and baking of the anodized portion of the chamfered metal frame, 312, wherein sealing the anodized metai frame may reduce the porosity and adsorption capacity of the oxide layer and improve the corrosion resistance of the anodized metal frame. The sealed surface may then be baked at a temperature of from about 60 °C to about 90 “C for a period of about 20 seconds to about 40 seconds. In an example, baking may be carried out at a temperature of from about 62 X to about 88 X for a period of about 30 seconds to about 40 seconds. In another example, the baking may be carried out at a temperature of 70 °C for a period of 40 seconds.

[0098] Prior to sealing and baking the anodized metal frame, the anodized metal frame may be cleaned, dried, washed, polished, degreased, and activated. The cleaning anti washing may be performed using a buffer solution, which may help in removing foreign particles, If any, present on the surface of the anodized metal frame. Further, the anodized metal frame may be chemically polished using abrasives to remove irregularities that may be present on the surface of the anodized metal frame. The anodized metai frame may also be degreased through ultrasonic degreasing methods to remove impurities, such as fat, grease, or oil from the surface of the anodized metai frame. The anodized metai frame may also be activated through acid treatment for removing the natural oxide layer, if any, present on the surface of the anodized metal frame. [0099] A method for forming a glossy casing for an electronic device or the method for forming an enclosure for an electronic device as described herein results in the formation of electronic device cover. A SD-sectiona! view of the electronic device cover is illustrated in Fig. 4, wherein

(a) represents an electronic device cover comprsing an injection-molded metal substrate 404, into a metal casing 402, a passivation layer 406 deposited on to the metai casing, and a protective layer 408 deposited on the passivation layer;

(b) represents the electronic device cover of (a), with a portion, 410, wherein chamfering may be done. The portion, 410, may be any portion of the device cover, such as cover edge, touch pad, fingerprint scanner, click pad, side wali, logo, among others: and

(c) represents a sectional view of an electronic device cover comprising an injection-molded metai substrate 404, into a metal casing 402; a passivation layer 406 deposited on to the metal casing; a protective layer 408 deposited on the passivation layer; and an anodic layer 412, deposited on the chamfered edge. [00100] Fig. 4 represents the electronic device cover formed by the methods as described hereinabove. The electronic device cover may comprise: a metal casing having a thickness of from about 0.3 mm to about 2.0 mm comprising thixo-molded magnesium-based alloy; at least one passivation iayer having a thickness of from about 1 μm to about 15 μm; at least one protective layer having a thickness of from about 5 μm to about 70 μm; and an anodic layer having a thickness of from about 3 μm to about 12 μm disposed on at least one chamfered portion of the casing.

[00101] In an example, metai casing, 402, may be a light metal casing selected from the group consisting of aluminum, magnesium, lithium, titanium, zinc, stainless steel, alloys thereof, and combinations thereof. In another example, the metai casing, may be a thixo-molded magnesium-based alloy, 404, into an aluminum alloy casing, 402. The presence of thixo-moided magnesium- based alloy, 404, into an aluminum alloy casing, 402, renders the metal casing chemico-mechanicai!y stable. In an example, the thixo-moided magnesium- based alloy provides a tensile strength of about 230 MPa, whereas a die casted aluminum alloy casing provides a tensile strength of about 324 MPa. The metal casing, may as a consequence have enhanced tensile strength owing to the presence of the thixo-mo!ded magnesium-based alloy, 404, into an aluminum alloy casing, 402.

[00102] The aluminum alloy casing, 402, may be formed from a fight metal alloy selected from AL575, AL105G, All 060, AL1100, AL1199, AL2014, AL2Q24, AL2219, AL3004, AL4041 , AL50G5, AL5010, AL5019, AL5024, AL5026, AL5050, AL5052, AL5Q56, AL5059, AL50S3, AL5086, AL5154, AL5182, AL5252, AL5254, AL5356, AL5454, AL5456, AL5457, AL5557, AL5652, AL5657, A15754, AL6005, AL6005A, AL6G60, AL6081 , A16063, AL6066, AL6070, AL6082, AL6105, AL6151 , AL6162, AL62G5, AL6282, AL6351 , AL6483, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079, AL7118, AL7129, AL7175, AL7475, AL7178, or combinations thereof, and the magnesium-based alloy for thixo-mo!ding may be selected from AZ63, AZ81, AZ91, AM50, AM60, AZ31, AZ81, AZ80, AE44, AJ62A, AL2391, AMCa802, LZ91 , or combinations thereof, in an example, the casing has a an aluminum frame and a thixo-molded magnesium-based alloy in a cavity of the frame.

[00103] In an example, the presence of the thixo-molded magnesium-based alloy, 404, into an aluminum alloy casing, 402, may lead to easy processing, lowering of the overall weight of the metal casing, thereby providing a lightweight frame. In an example, the metal casing may be of a thickness in a range of from about 0.3 to 2.0 mm. In another example, the metal casing may be of a thickness in a range of from about 0.5 to 1.8 mm. In yet another example, the metal casing may be of a thickness of 0.7 mm.

[00104] Referring to Fig. 4, in an example, at least one passivation layer, 408, may be deposited on the metal casing. The passivation layer may be deposited by a micro-arc oxidation process or may be deposited by a dip coating process, in case of micro-arc oxidation process, the passivation layer, 406, may have a thickness of from about 2 μm to about 15 μm. In another example, the passivation layer deposited by micro-arc oxidation may have a thickness of from about 3 μm to about 12 μm. in yet another example, the passivation iayer deposited by micro- arc oxidation may have a thickness of from about 3 μm to about 7 μm. [00105] In an example, when the passivation layer, 406, is deposited by a dip- coating process, the passivation layer, 406, may have a thickness of from about 1 μm to about 5 μm. In another example, the passivation layer obtained by the process of dip coating may have a thickness of from about 1.5 μm to about 3.0 μm.

[00106] The electronic device cover may comprise at least one protective layer, 408, onto the at least one passivated layer, 406. In an example, the protective layer may have a thickness in a range of from about 5.0 μm to about 70.0 μm. In another example, the protective layer may have a thickness in a range of from about 10.0 μm to about 68.0 μm. In yet another example, the protective layer may have a thickness in a range of from about 10.0 μm to about 65.0 μm. [00107] In another example, the at least one protective layer may be a single layer or may comprise multiple layers, such as primer coat base coat, and top coat.

[00108] In an example, the at least one protective layer comprises sequentially a primer coat having a thickness of from about 5.0 μm to about 20.0 μm, a base coat having a thickness of from about 10.0 μm to about 20.0 μm, and a top coat having a thickness of from about 10.0 μm to about 25.0 μm.

[00109] The protective layer may comprise primer, either alone or in combination with additional layers. The primer may also be applied as single or multiple coats to achieve the desired thickness and finish. In an example, the primer may have a thickness of from about 5.0 μm to about 20.0 μm. In another example, the primer may have a thickness of from about 8.0 μm to about 18,0 μm . In yet another example, the primer may have a thickness of about 12.0 μm. [00110] The protective layer may comprise a base coat, in combination with additional layers. The base coat may also be applied as single or multiple coats to achieve the desired thickness and finish. In an example, the base coat may have a thickness of from about 10.0 μm to about 20.0 μm. In another example, the base coat may have a thickness of from about 12.0 μm to about 18.0 μm. In yet another example, the base coat may have a thickness of about 15,0 μm. [00111] The protective layer may comprise top coat, in combination with additional layers. The top coat may also be applied as single or multiple coats to achieve the desired thickness and finish, in an example, the top coat may have a thickness of from about 10.0 μm to about 25.0 μm. in another example, the top coat may have a thickness of from about 12.0 μm to about 22.0 μm. In yet another example, the top coat may have a thickness of about 17.0 μm.

[00112] Further, the chamfering, 410, may be carried out at areas selected from the group consisting of cover edge, touch pad, fingerprint scanner, click pad, side wall, logo, and combinations thereof, followed by deposition of an anodic layer, 412. in an example, at least a portion of the metal casing Is chamfered to obtain glossy chamfered edges. The portions of the metal casing wherein chamfering may be done is selected from may be cover edge, touch pad, fingerprint scanner, click pad, side wail, logo, among others. The chamfering involves abrasive removal of edge material that can give it the desired finishing and also shape its form. In an example, chamfering may be carried out by a CNC diamond cutting machine, in another example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 5000 to about 90000 rμm for a period in a range of from about 3 to about 8 minutes, in yet another example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 6000 to about 80000 rμm.

[00113] Further, the chamfered portions may be anodized to obtain an anodic iayer over the chamfered portion. Forming anodic layers protect and cosmetically enhance metal surfaces are described. The underlying metal surface may be visible through the anodic iayer thereby enhancing the aesthetic appeal of the electronic device cover. Electronic devices tend to have sharp corners and edges that make it difficult to form a consistent and cosmetically appealing anodic layer thereon. In an example, the anodic layer may have a thickness of from about 3.0 μm to about 12.0 μm. In another example, the anodic Iayer may have a thickness of from about 5.0 μm to about 12.0 μm, in yet another example, the anodic Iayer may have a thickness of from about 7.0 μm to about 12.0 μm. In another example, the anodic Iayer may have a thickness of about 10 μm. The thickness of the anodic layer achieved may be directly related to the potential applied and time employed in the process of anodization. [00114] In an example, the anodic layer described herein, may in addition to protection, also cosmetically enhance the look and feel of metal surfaces of electronic devices. The anodic layer may be transparent in order to reveal features of the underlying metal surface. The underlying metal surface may have a reflective shine or ornamental features which would be viewable through the transparent anodic layer,

[00115] In an example, the electronic device cover, 400, may comprise at least one anti-fingerprint coating having a thickness of from about 10 nm to about 100 nm . The anti-finger print coating may comprise hydrophobic coating materials selected from fluorinated olefin-based polymers, that is, fiuoroacrytates, fluorosiiicone acrylates, fluorourethanes, periuoropolyethers, perfluoropoSyoxetanes, fluorotelomers (C ₁ -C ₆ ), polytetrafiuoroethylene (PTFE), polyvinylidenefluouride (PVDF), fluorosiloxane, fluoro UV polymers, hydrophobic polymers (C ₇ -C ₂₀ ), or combinations thereof, in an example, the anti-fingerprint coating may include features disposed on the surface that are light-scatering (transmittance). In another example, the features may be disposed directly on the surface or indirectly on the surface in a random or non-random manner. In yet another example, randomiy disposed features may provide a smooth touch- feeling when the surface is contacted or swiped with a finger or skin. In an example, the anti-fingerprint coating of the present disclosure may maintain metallic luster (gloss) with high abrasion resistance.

[00118] The electronic device cover 400, may reveal an enhanced gloss value of from about 80 to about 95 units as measured by American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 80". In another example, the electronic device cover, 400, may reveal a gloss value of from about 82 to about 93 units. In yet another example, the electronic device cover, 400, may reveal a gloss value of about 92 units,

[00117] In an example, the electronic device cover, 400, may have a tensile strength of from about 200 MPa to about 700 MPa as measured by American Society for Testing and Materials (ASTM) 0790, In another example, the electronic device cover, 400, a tensile strength of from about 250 MPa to about 600 MPa as measured by American Society for Testing and Materials (ASTM) D79G, In yet another example, the electronic device cover, 400, a tensile strength of from about 350 MPa to about 600 MPa as measured by American Society for Testing and Materials (ASTM) D790.

[00118] In an example, the device cover of the present disclosure may be employed for electronic devices, such as keyboards, tablets, mobile phones, smartwatches, laptops, and the like, in an example, the device cover, 400 may be used as a body or frame for keyboards of computers or laptops.

[00119] Although examples for the present disclosure have been described in a language specific to structural features and/or methods, it is to be understood that the appended claims are not limited to the specific features or methods described herein. Rather, the specific features and methods are disclosed and explained as examples of the present disclosure.