WO2021177977A1

WO2021177977A1 - Covers or enclosures for an electronic device

Info

Publication number: WO2021177977A1
Application number: PCT/US2020/021579
Authority: WO
Inventors: Kuan-Ting Wu; Ya-Ting Yeh; Te-Shun LEE
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2021-09-10

Abstract

Examples of metal composite cover/enclosure for an electronic device have been described. In an example, the cover includes a metal frame comprising a first metal alloy substrate and an injection-molded second metal alloy substrate adjacent to the first metal alloy substrate; an electrophoretic deposition layer on the metal frame; and an anodic layer on at least a chamfered portion of the first metal alloy substrate

Description

COVERS OR ENCLOSURES FOR AN ELECTRONIC DEVICE

BACKGROUND

[0001] Mass reduction of electronic devices, such as keyboards, tablets, laptops, and the like, has generally been carried out by material substitution, for example, by use of light metals, such as magnesium alloys and aluminum alloys instead of heavier metals and alloys. In addition to mass reduction, the light metals also provide excellent mechanical properties, low density, and high strength-to-weight characteristics. Hence, covers or enclosures for electronic devices may be manufactured from suitable light metals resulting in the reduction of weight without compromising on the aesthetic appearance and mechanical strength. For aesthetic appearance, the outer surface of the covers or enclosures may be suitably treated.

BRIEF DESCRIPTION OF DRAWINGS

[0002] The following detailed description references the drawings, wherein: [0003] Fig. 1 illustrates a sectional view of the metal composite cover for an electronic device, according to an example of the present disclosure;

[0004] Fig. 2 shows a sectional view of the metal composite cover for an electronic device with a passivation layer, according to an example of the present disclosure;

[0005] Fig. 3 illustrates a sectional view of the enclosure for an electronic device, according to an example of the present disclosure:

[0006] Fig. 4 shows a sectional view of the enclosure for an electronic device comprising at least one decorative layer, according to an example of the present disclosure;

[0007] Fig. 5 is a flow chart illustrating a method for forming an enclosure for an electronic device, according to an example of the present disclosure; DETAILED DESCRIPTION

Definitions

[0008] 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 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.

[0009] The articles "a," “an," and “the" are used to refer to one or more than one (i.e., to at least one) of the grammatical object of the article.

[0010] 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 plus or minus 5 to 10 percent of the stated numerical value.

[0011] Composite covers/enclosures of electronic devices are made of metal frames that have high strength and resistance towards corrosion. Examples of this disclosure pertain to suitable materials for such composite covers/enclosures that have aesthetic appeal, are light in weight, and at the same time, impart adequate mechanical strength. The examples herein pertain to composite covers/enclosures including an injection-molded magnesium alloy substrate adjacent to the aluminum alloy substrate. As used herein, the terms "enclosure" may be used interchangeably with "metal composite covers," "housing ” and "cover or protective cover," Such enclosures may form a back surface of an electronic device, front cover, and/or any of the edges of the electronic device. [0012] 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, AL1060, AL1100, AL1199, AL2014, AL2024, AL2219, AL3004, AL4041, AL5005, AL5010, AL5019, AL5024, AL5026, AL5050, AL5052, AL5056, AL5059, AL5083, AL5086, AL5154, AL5182, AL5252, AL5254, AL53S6, AL5454, AL54S6, AL5457, AL5557, AL5652, AL5657, AL5754, AL6005, AL6005A, AL6060, AL6061, AL6063, AL6066, AL6070, AL6082, AL6105, AL6151, AL6182, AL6205, AL6262, AL6351 , AL6463, AL7005, AL7022, AL 7088, AL7072, AL7075, AL7079, AL7116, AL7129, AL717S, AL7475, AL7178 or combinations thereof. The magnesium alloy in the present disclosure is selected from AZ83, AZ81 , AZ91, AM50, AM60, AZ31, AZ61, AZ80, AE44, AJ62A, ALZ391 , AMCa602, LZ91 , magnox, or combinations thereof.

[0013] The term “molded” and variations, such as “molding” “Injecting,” used herein refer to injection-molding of an alloy, i.e., magnesium alloy.

[0014] The term “injection-molding,” or “injecting” used herein refers to a technique for manufacturing parts by injecting molten material into a mold, or a cavity of the frame made up of one another material, injection-molding may he carried out by a process, such as thixo-moidlng or die-casting, at a temperature of from about 200 °C to about 500 °C. An insert of an aluminum alloy may be pre- formed to form a part and may be placed in a mold. Magnesium alloy maybe then injection-molded at least partially around the insert of aluminum alloy. For instance, molten magnesium alloy can be injected into the mold to become a composite part of the frame, so as to obtain a metal frame. Upon cooling, the metal frame may be removed and obtained in the desired shape.

[0015] The term “substrate,” used herein, refers to a frame containing aluminum alloy, magnesium alloy, or aluminum alloy adjacent to the magnesium alloy that is used to obtain the metal composite cover/enclosure for an electronic device of the present disclosure. The substrate can be obtained by injection- molding techniques, such as thixo-moidlng or die-casting,

[0018] The term “mechanically stable,” used herein, refers to substrates having high tensile strength, high resistance to breakage, and/or high corrosion resistance.

[0017] The term “high gloss edges," used herein, refers to chamfered surfaces (in particular, the edges) of the substrate that reveal shiny edges.

[0018] The term “pre-forming" used herein refers to forming a part by a process selected from stamping, forging, computer numerical control (CNC), or combinations thereof.

[0019] The term “putty agents" refers to polyurethane, polyester, epoxy putty containing 12-60 wt% clay, talc, titanium dioxide, glass beads, and calcium carbonate. [0020] Reduction in weight of the enclosures may be achieved by the usage of dissimilar lightweight metal alloys, i.e., joining (Junction) of aluminum alloys and magnesium alloys. In portions of the metal frame where stress is expected to he low, the magnesium alloy may he substituted with aluminum alloy to achieve weight reduction without compromising on mechanical strength. Substitution of magnesium alloys for aluminum alloys would achieve weight reduction. Various junction methods are known, such as fusion welding, solid-state welding, diffusion-welding, among others. These welding techniques were found to be unsuitable because of the presence of intermetallic compounds formed in the weld, which adversely affects the performance of the material, rendering it brittle. The resultant junctions achieved by welding lacked sufficient structural integrity. Moreover, gaps or void formation occurs at the junction interface area between the aluminum alloy region and the magnesium alloy region.

[0021] Despite the above welding processes, there exists a need for efficient molding technique compatible with dissimilar metal alloys to increase the aesthetic and visual effects of the composite covers/enclosures without causing cracking, voids, or gap formation during the manufacturing of such composite covers/enclosures. This need is evident in the electronic industry, wherein the aesthetic appeal and visual effects, including the size/thickness of an electronic device, may be just as significant to the consumer as the practical working of the electronic device. Moreover, to achieve aesthetic appeal in the metal composite covers/enclosures, 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.

[0022] The present subject matter describes a metal composite cover/enclosure and a method for faming an enclosure. Such a composite cover/enclosure may be used for housing the structural parts, mechanical parts in electronic equipment of an electronic device.

[0023] The present disclosure illustrates examples of metal composite cover/enclosure for an electronic device formed by injection-molding a magnesium alloy substrate adjacent to the aluminum alloy substrate to form a metal frame. The injection-molding of the magnesium alloy substrate adjacent to the aluminum alloy substrate provides an enhanced design flexibility, reliability, a low porosity, a uniform microstructure for the metal composite cover/enclosure with enhanced mechanical and surface finish properties. As every part is tightly secured in the metal frame, part loosening, misalignment, improper terminations, and other problems do not occur thereby enhancing the reliability. Injection- molding helps in joining dissimilar metal alloys in a single stage, which may reduce assembly and labor-related costs. Moreover, reduction in size and weight may be achieved by combining the physical strength of the injection-molded second metal alloy substrate (magnesium alloy substrate) with the first metal alloy substrate (aluminum alloy substrate). The metal frame may be passivated by depositing a passivation layer to obtain a passivated metal frame. The passivation may be carried out by a process selected from chemical passivation treatment, electro-chemical passivation treatment, or combinations thereof.

[0024] Further to the deposition of the passivation layer, an electrophoretic deposition layer may be coated. The electrophoretic deposition layer coated on to the metal frame or the passivated metal frame may provide decorative effects (decorative finish), corrosion protection (form a protective barrier against environment exposure), and bonding enhancement in the junction area. The electrophoretic deposition layer may also fill and seal small surface pits and interconnected subsurface porosity. To obtain high gloss finish at the edges of the metal composite cover/enclosure, the aluminum alloy region of the metal frame may be chamfered. Chamfering may be carried out on at least a portion of the aluminum alloy region by a CMC diamond cutting machine. The chamfering may be carried out at portions of the composite cover/enclosure where a different aesthetic appeal is to be provided as compared to the rest of the cover/enclosure, such as cover edge, touchpad, click-pad, fingerprint scanner, edge, or sidewall, area where the logo is to be provided, and the like.

[0025] Further, an anodic layer may be deposited at the chamfered portions, which may provide high gloss finish at those areas. The anodic layer on the chamfered portions may enhance the natural corrosion resistance of the aluminum alloy substrate apart from delivering high gloss finish. The anodic layer may be deposited on the chamfered portions by an electrochemical process that converts aluminum Into aluminum oxide. The thickness of the anodic layer may be increased to develop a wear-resistant hard coat. The resultant anodic layer may be harder than the underlying metal, providing a coating that provides structural integrity and durability, apart from providing aesthetic appeal at the edges of the electronic device without increasing its weight. The aesthetic appeal of thus obtained metal composite cover/enclosure may be quantified by measuring the gloss value. The gloss value of the metal composite cover/enclosure for an electronic device may be from about 80 units to about 100 units as measured by the American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 60°.

[0026] Overall, the metal composite cover/ enclosure for an electronic device, according to the present subject matter, is aesthetically appealing, light in weight, while also being mechanically stable. Moreover, the method for forming an enclosure is simple, less time consuming, less resource consuming, and cost- efficient.

[0027] The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the foiiowing 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.

[0028] Fig. 1 illustrates a sectional view of the metal composite cover for an electronic device 100, according to an example of the present disclosure. The metal composite cover comprises a metal frame comprising a first metal alloy substrate 102, and an injection-molded second metal alloy substrate 104, adjacent to the first metal alloy substrate 102, an electrophoretic deposition layer 106 on the metal frame, and an anodic layer 108 on at least a chamfered portion of the first metal alloy substrate 102. [0029] The metal frame of Fig. 1 comprises a first metal alloy substrate 102. adjacent to the injection-molded second metal alloy substrate 104, in an example, the first metal alloy substrate 102, is an aluminum alloy, The aluminum alloy may be selected from AL575, AL1050, AL1060, AL1100, AL1139, 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, AL6005, AL6005A, AL6060, AL6061, AL6063, AL6066, AL6070, AL6082, AL6105, AL6151, AL6162, AL6205, AL6262, AL6351, AL6463, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079, AL7116, AL7129, AL7175, AL7475, AL7178, or combinations thereof. In an example, injection-molded second metal alloy substrate 104, is magnesium alloy and may be selected from AZ63, AZ81 , AZ91, AM50, AM60, AZ31, AZ61, AZ80, AE44, AJ62A, ALZ391, AMCa602, 1291, magnox, or combinations thereof .

[0030] In an example, the metal frame of the present disclosure may have a thickness of from about 0.3 mm to about 2,0 mm. In another example, the metal frame may have a thickness of from about 0.5 to 1.8 mm. In yet another example, the metal frame may have a thickness of 0.7 mm.

[0031] In an example, the metal frame comprising a first metal alloy substrate and an injection-molded second metal alloy substrate adjacent to the first metal alloy substrate may have a tensile strength of from about 200 MPa to about 700 MPa as measured by the American Society for Testing and Materials (ASTM) D790. In another example, the metal frame of the present disclosure may have 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, the metal tame of the present disclosure may have a tensile strength of from about 350 MPa to about 600 MPa as measured by American Society for Testing and Materials (ASTM) 0799.

[0032] In an example, the metal composite cover 100 comprises an electrophoretic deposition layer 106 on the metal frame. The electrophoretic deposition layer 106 may seal the junction gap or voids, i.e., fills and seals small surface pits and interconnected subsurface porosity, between the first metal alloy substrate 102 and the injection-molded second metal alloy substrate 104. In an example, the electrophoretic deposition layer extends over both the first metal alloy substrate 102 and the injection-molded second metal alloy substrate 104. The electrophoretic deposition layer may prevent the penetration of putty agents, primer paint, and/or anodizing chemicals, which may cause reliability issues and delamination between the first metal alloy substrate and the injection-molded second metal alloy substrate. The electrophoretic deposition layer 108, present on the metal frame, may provide decorative effects (decorative finish), corrosion protection (form a protective barrier against environment exposure), or bonding enhancement in the junction area. In an example, the electrophoretic deposition layer 106 may be transparent. Various kinds of copolymers may be employed while coating the electrophoretic deposition layer. The copolymers may be selected from polyacryiate copolymer, polyacrylic, epoxy, polyacrylamide-acrylic, and combinations thereof. In an example, the electrophoretic deposition layer 106 may comprise copolymers of polyacryiate, in another example, the electrophoretic deposition layer 106 may comprise copolymers of polyacrylamide- acrylic. The acrylic type electrophoretic deposition layer may be transparent and may also fill and seal small surface pits and interconnected subsurface porosity at the interface regions of the first metal alloy substrate and the injection-molded second metal alloy substrate.

[0033] In an example, the electrophoretic deposition layer 106 may have a thickness of from about 5.0 μm to about 30.0 μm, in another example, the electrophoretic deposition layer 106 may have a thickness of from about 6.0 μm to about 25.0 μm. In yet another example, the electrophoretic deposition layer 106 may have a thickness of from about 10.0 μm to about 25.0 μm. In some examples, the electrophoretic deposition layer 106 may have a thickness of from about 15.0 μm to about 20.0 μm. In another example, the electrophoretic deposition layer 106 may have a thickness of about 15.0 μm.

[0034] Chamfering may be performed, for example, to remove defects or provide high gloss finishes, at the edges/sides of the metal composite cover/ enclosure. The first metal substrate 102, may be chamfered. The chamfering may be carried out at portions of the composite cover/enclosure where a different aesthetic appeal Is to be provided as compared to the rest of the cover/enclosure, such as cover edge, touchpad, click-pad, fingerprint scanner, edge, sidewall, hinge cap, area where the logo is to be provided, and the like. Chamfering may involve abrasive removal of edge material and eventually may provide even surface at the edges with the desired finish and enhanced strength.

[0035] In an example, an anodic layer 108 may be deposited on at least a chamfered portion of the first metal alloy substrate, which may help to provide high gloss finish at chamfered portions. The anodic layer on the chamfered portions may enhance the natural corrosion resistance of the first metal alloy substrate. The anodic layer may be deposited on the chamfered portions by an electrochemical process that converts aluminum into aluminum oxide. The thickness of the anodic layer may be increased to develop a wear-resistant hard coat. 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.

[0036] In an example, the anodic layer 108 may have a thickness of from about 7.0 μm to about 15.0 μm. In another example, the anodic layer 108 may have a thickness of from about 8.0 μm to about 12.0 μm, in yet another example, the anodic layer 108 may have a thickness of from about 8.0 μm to about 10.0 μm. In some examples, the anodic layer 108 may have a thickness of about 9.0 μm.

[0037] The aesthetic quality of thus obtained cover/enclosure 100, may be quantified by measuring a gloss value. The gloss value of the metal composite cover/enclosure for an electronic device may be from about 80 units to about 100 units as measured by the American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 60°. In another example, the cover/enclosure 100, may reveal a gloss value of from about 85 to about 95 units. In yet another example, the cover/enclosure 100, may reveal a gloss value of about 92 units. In an example, the cover/enclosure 100 of the present disclosure may have a tensile strength of from about 200 MPa to about 700 MPa as measured by the American Society for Testing and Materials (ASTM) D790. In another example, the cover/enclosure 100 of the present disclosure may have a tensile strength of from about 250 MPa to about 600 MPa as measured by the American Society for Testing and Materials (ASTM) D790. In yet another example, the cover/enclosure 100 of the present disclosure may have a tensile strength of from about 350 MPa to about 600 MPa as measured by the American Society for Testing and Materials (ASTM) D790-

[0038] Another example of the metal composite cover for an electronic device is shown In Fig. 2. Fig. 2 illustrates a sectional view of the metal composite cover 200, comprising a metal frame comprising a first metal alloy substrate 202, and an injection-molded second metal alloy substrate 204, adjacent to the first metal alloy substrate; at least one passivation layer 210; an electrophoretic deposition layer 206 on the passivated metal frame; and an anodic layer 208, on at least a chamfered portion of the first metal alloy substrate 202.

[0039] The metal frame comprises a first metal alloy substrate 202, adjacent to the injection-molded second metal alloy substrate 204. In an example, the first metal alloy substrate 202, is an aluminum alloy. The aluminum alloy may be selected from AL575, AL1050, 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, AL6005, AL6005A, AL6060, AL6061, AL6063, AL6066, AL6070, AL6082, AL6105, AL6151, AL6162, AL6205, AL6262, AL6351, AL6463, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079, AL7116, AL7129, AL7175, AL7475, AL7178, or combinations thereof. In an example, injection-molded second metal alloy substrate 204, is magnesium alloy and may be selected from AZ63, AZ81 , AZ91 AM50, AM60, AZ31 , AZ61, AZ80, AE44, AJ62A, ALZ391, AMCa602, LZ91, magnox, or combinations thereof,

[0040] In an example, the metal frame may have a thickness of from about 0.3 mm to about 2.0 mm. in another example, the metal frame may have a thickness of from about 0.5 to 1.8 mm. In yet another example, the metal frame may have a thickness of 0.7 mm. [0041] In an example, the metal frame of the present disclosure may have 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, the metal frame of the present disclosure may have 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, the metal frame of the present disclosure may have a tensile strength of from about 350 MPa to about 600 MPa as measured by American Society for Testing and Materials (ASTM) D790.

[0042] The metal composite cover 200 may comprise at least one passivation layer 210. In an example, at least one passivation layer may be deposited on the metal frame to obtain a passivated metal frame. In an example, at least one passivation layer 210 may be deposited by electro-chemical passivation treatment, in another example, at least one passivation layer 210 may be deposited by a process of dip coating. The method of deposition may result in varied thickness ranges of the at least one passivation layer.

[0043] In an example, the at least one passivation layer formed by micro-arc oxidation may have a thickness of from about 2.0 μm to about 15.0 μm. In another example, the at least one passivation layer formed by micro-arc oxidation may have a thickness of from about 3.0 μm to about 12.0 μm. In yet another example, the at least one passivation layer formed by micro-arc oxidation may have a thickness of from about 3.0 μm to about 7.0 μm.

[0044] In an example, the at least one passivation layer obtained by the process of dip coating may have a thickness of from about 1.0 μm to about 5,0 μm. in another example, the at least one passivation layer obtained by the process of dip coating may have a thickness of from about 1,5 μm to about 3.0 μm.

[0045] In an example, electrophoretic deposition layer 206, may be coated on the passivated metal frame. The electrophoretic deposition layer 206 may sea! the junction gap or voids (fill and seal small surface pits and interconnected subsurface porosity) on the passivated metal frame. The electrophoretic deposition layer may prevent the penetration of putty agents, primer paint, and/or anodizing chemicals, which may cause reliability issues and delamination on the passivated metal frame. The electrophoretic deposition layer 206, coated on to the passivated metal frame, may provide decorative effects (decorative finish), corrosion protection (form a protective barrier against environment exposure), or bonding enhancement in the junction area. In an example, the electrophoretic deposition layer 206, may be transparent. Various kinds of copolymers may be employed while mating the electrophoretic deposition layer. The copolymers may be selected from polyacrylate copolymer, polyacrylic, epoxy, polyacrylamide- acrylic, and combinations thereof, in an example, the electrophoretic deposition layer 206 may comprise copolymers of polyacrylate. In another example, the electrophoretic deposition layer 206 may comprise copolymers of polyacrylamide- acrylic. The acrylic type electrophoretic deposition layer may be transparent and may also fill and seal small surface pits and interconnected subsurface porosity at the passivated metal frame.

[0046] In an example, the electrophoretic deposition layer 206 may have a thickness of from about 5.0 μm to about 30.0 μm, In another example, the electrophoretic deposition layer 206 may have a thickness of from about 8.0 μm to about 25.0 μm. In yet another example, the electrophoretic deposition layer 206 may have a thickness of from about 10.0 μm to about 25.0 μm, in some examples, the electrophoretic deposition layer 206 may have a thickness of from about 15.0 μm to about 20.0 μm. In other examples, the electrophoretic deposition layer 206 may have a thickness of about 15.0 μm.

[0047] The metal composite cover may have defects at the edges. To eliminate the defects and to obtain high gloss finish at the edges/sides of the metal composite cover/ enclosure, the first metal substrate 202, may be chamfered. The chamfering may be carried out at portions of the composite cover/enclosure where a different aesthetic appeal is to be provided as compared to the rest of the cover/enclosure, such as cover edge, touchpad, click-pad, fingerprint scanner, edge, sidewall, hinge cap, area where the logo is to be provided, and the like. Chamfering may Involve abrasive removal of edge material and eventually may provide even surface at the edges with the desired finish and enhanced strength. [0048] In an example, an anodic layer 208 may be deposited on at least a chamfered portion of the first metal alloy substrate, which may provide high gloss finish at chamfered portions. The anodic layer 208 on the chamfered: portions may enhance the natural corrosion resistance of the first metal alloy substrate. The anodic layer may be deposited on the chamfered portions by an electrochemical process that converts aluminum into aluminum oxide. The thickness of the anodic layer may be increased to develop a wear-resistant hard coat 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.

[0049] In an example, the anodic layer 208 may have a thickness of from about 7.0 μm to about 16.0 μm. In another example, the anodic layer 208 may have a thickness of from about 8.0 μm to about 12.0 μm. In yet another example, the anodic layer 208 may have a thickness of from about 8.0 μm to about 10.0 μm. In some examples, the anodic layer 208 may have a thickness of about 9.0 μm. In an example, the anodic layer described herein, may in addition to protection, also cosmetically enhance the look and feel of chamfered edges of the metal composite covers for 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.

[0050] The aesthetic quality of thus obtained cover/enclosure 200, may be quantified by measuring a gloss value. The gloss value of the metal composite cover/enclosure for an electronic device may be from about 80 units to about 100 units as measured by the American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 601 in another example, the cover/enclosure 200, may reveal a gloss value of from about 85 to about 95 units. In yet another example, the cover/enclosure 200, may reveal a gloss value of about 92 units. In an example, the cover/enclosure 200, of the present disclosure may have 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, the cover/enclosure 200 of the present disclosure may have a tensile strength of from about 250 MPa to about 800 MPa as measured by the American Society for Testing and Materials (ASTM) D790. In yet another example, the cover/enclosure 200, of the present disclosure may have a tensile strength of from about 350 MPa to about 800 MPa as measured by American Society for Testing and Materials (ASTM) D790.

[0051] The present disclosure also describes an enclosure for an electronic device and a sectional view of the enclosure for an electronic device 300, according to an example of the present disclosure is illustrated in Fig. 3. The enclosure may have various areas wherein dissimilar metal alloys are present. When dissimilar metal alloys, such as aluminum alloys and/or magnesium alloys are joined, for example, by injection molding, to obtain lightweight enclosures, a junction interface 312 may be visible at the at least one aluminum alloy region and the at least one magnesium alloy region. After passivation the junction becomes a passivated junction interface. These Junction interfaces may be suitably treated to obtain stabilized high-gloss enclosures with enhanced mechanical strength,

[0052] In Fig. 3, a metal frame Is shown which comprises at least one aluminum alloy region 302, and at least one magnesium alloy region 304. The sectional view of the enclosure 300, includes a passivation layer 310, which is present on the at ieast one aluminum alioy region 302, the at least one magnesium alioy region 304, and at least a junction interface 312, of the at Ieast one aluminum alloy region and the at least one magnesium alloy region, in an example, the passivation layer 310, on the at least one aluminum alloy region results in the formation of passivated aluminum alloy region. The enclosure also comprises an electrophoretic deposition layer 308, on at least a passivated junction interface of the at least one aluminum alloy region and the at Ieast one magnesium alloy region; and an anodic layer on at Ieast a chamfered portion of the aluminum alloy region. In an example, the electrophoretic deposition layer 308, may also be present on the at least one passivated aluminum alloy region. In another example, the electrophoretic deposition layer 308, may also be present on the at least one passivated magnesium alloy region. The enclosure may have an anodic layer 308, on at least a chamfered portion of the aluminum alloy region. [0053] In an example, the enclosure for an electronic device comprises a metal frame comprising at least one aluminum alloy region 302, and at least one magnesium alloy region 394; at least one passivation layer 310, an electrophoretic deposition layer 306, on at least a passivated Junction interface 312, of the at least one aluminum alloy region and the at least one magnesium alloy region; and an anodic layer, 308 on at least a chamfered portion of the aluminum alloy region.

[0054] In an example, the aluminum alloy region 302, is made up of an aluminum alloy selected from AL575, AL1050, AL1060, AL1100, AL1199, AL2014. AL2024, AL2219, AL3004, AL4041 , AL5005, AL5010, AL5019, AL5024, AL5026, AL5050. AL5052, AL5058, AL5059, AL5083, AL5086, AL5154, AL5182, AL5252, AL5254, AL5356, AL5454, AL5456, AL5457, AL5557, AL5652, AL5657, AL5754, AL6005, AL6005A, AL6060, AL6061, AL6063, AL6066, AL6070, AL6082, AL6105, AL6151 , AL6162, AL6205, AL6262, AL6351, AL6463, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079, AL7116, AL7129, AL7175, AL7475, AL7178, or combinations thereof, in an example, magnesium alloy region may be made up of magnesium alloy selected from AZ83, AZ81 , AZ91, AM50, AM60, AZ31, AZ61, AZ80, AE44, AJ62A, ALZ391, AMCa602, 1291 magnox, or combinations thereof.

[0055] In an example, the enclosure comprises a metal frame having a thickness of from about 0.3 mm to about 2.0 mm. In another example, the enclosure comprises a metal frame having a thickness of from about 0.5 to 18 mm. In yet another example, the enclosure comprises a metal frame having a thickness of 0.7 mm.

[0056] In an example, the enclosure comprises a junction interface, which may be passivated by deposition of a passivation layer to obtain a passivated junction interface. The junction interface may be interface wherein dissimilar metal alloys join, i.e., the junction between the at least one aluminum alloy region and the at least one magnesium alloy region.

[0057] In an example, the enclosure comprises at least one passivation layer

310. The passivation layer may be deposited on the metal frame to obtain a passivated metal frame. In some examples, the passivation layer may be deposited on the aluminum alloy region or the magnesium alloy region or both. In another example, the passivation layer may be deposited on the junction interface of the aluminum alloy region and the magnesium alloy region to obtain the passivated junction interface 312. In an example, the passivated junction interface may be obtained by depositing the passivation layer by electro-chemical passivation treatment. The electrochemical passivation treatment may be a micro-arc oxidation process. In another example, the passivated junction interface may be obtained by depositing the passivation layer by a process of dip coating. The method of deposition may result in varied thickness ranges of the passivated junction interface. In an example, the passivated junction Interface may have a thickness of from about 1.0 μm to about 15.0 μm.

[0058] In an example, the passivated junction interface formed by electro- chemical passivation treatment may have a thickness of from about 2.0 μm to about 15.0 μm. In another example, the passivated junction interface formed by electro-chemical passivation treatment may have a thickness of from about 3,0 μm to about 12.0 μm. In yet another example, the passivated junction Interface formed by electro-chemical passivation treatment may have a thickness of from about 3.0 μm to about 7.0 μm.

[0059] In an example, the passivated junction interface formed by the process of dip coating may have a thickness of from about 1.0 μm to about 5.0 μm. In another example, the passivated junction interface formed by the process of dip coating may have a thickness of from about 15 μm to about 3.0 μm. The passivation layer on the metal frame may prohibit oxidation at the surface of the metal alloys.

[0060] In an example, the enclosure comprises electrophoretic deposition layer 306, on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region. The electrophoretic deposition layer 306 may seal the junction gap or voids (fill and seal small surface pits and interconnected subsurface porosity) on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region. The electrophoretic deposition layer may prevent the penetration of putty agents, primer paint, and/or anodizing chemicals, which may cause reliability issues and delamination on at least a passivated Junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region. The electrophoretic deposition layer 306, coated on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region may provide decorative effects (decorative finish), corrosion protection (form a protective barrier against environment exposure), bonding enhancement in the junction area. In an example, the electrophoretic deposition layer 306 may be transparent Various kinds of copolymers may be employed while coating the electrophoretic deposition layer. The copolymers may be selected from polyacrylate copolymer,polyacrylic, epoxy, polyacrylamide-acrylic, and combinations thereof. In an example, the electrophoretic deposition layer 306 may comprise copolymers of polyacrylate. In another example, the electrophoretic deposition layer 306 may comprise copolymers of polyacrylamide-acrylic. The acrylic type electrophoretic deposition layer may be transparent and may also fill and seal small surface pits and interconnected subsurface porosity on at least a passivated junction Interface of the at least one aluminum alloy region and the at least one magnesium alloy region.

[0061] In an example, the electrophoretic deposition layer 306 on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region, may have a thickness of from about 5.0 μm to about 30.0 μm. In another example, the electrophoretic deposition layer 306 may have a thickness of from about 6.0 μm to about 25.0 μm, in yet another example, fhe electrophoretic deposition layer 306 may have a thickness of from about 10.0 μm to about 25.0 μm. In some examples, the electrophoretic deposition layer 306 may have a thickness of from about 15,0 μm to about 20.0 μm. In another example, the electrophoretic deposition layer 306 may have a thickness of about 15.0 μm.

[0062] The enclosure for an electronic device may have defects at the edges. To eliminate the defects and to obtain high gloss finish at the edges/sides of the enclosure, the first metal substrate 302, may be chamfered. The chamfering may be carried out at portions of the enclosure where a different aesthetic appeal is to be provided as compared to the rest of the enclosure, such as cover edge, touchpad, click-pad, fingerprint scanner, edge, sidewall, hinge cap, area where the logo is to be provided, and the like. Chamfering may involve abrasive removal of edge material and eventually may provide even surface at the edges with the desired finish and enhanced strength,

[0063] In an example, the enclosure comprises an anodic layer 308, on at least a chamfered portion of the aluminum alloy region 302. The anodic layer 308 may provide high gloss finish at chamfered portions and may enhance the natural corrosion resistance of the aluminum alloy region 302. The anodic layer may be deposited on the chamfered portions by an electrochemical process that converts aluminum alloy into Its oxide form, 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. The thickness of the anodic layer may be increased to develop a wear-resistant hard coat.

[0064] In an example, the anodic layer 308 may have a thickness of from about 7.0 μm to about 15.0 μm. In another example, the anodic layer 308 may have a thickness of from about 8.0 μm to about 12.0 μm. In yet another example, the anodic layer 308 may have a thickness of from about 8.0 μm to about 10.0 μm. In some examples, the anodic layer 308 may have a thickness of about 9.0 μm. In an example, the anodic layer described herein, may in addition to protection, also cosmetically enhance the look and feel of chamfered edges of the enclosure for 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.

[0065] The aesthetic quality of thus obtained enclosure 300, may be quantified by measuring a gloss value, The gloss value of the enclosure for an electronic device may be of from about 80 units to about 100 units as measured by the American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 60°. In another example, the enclosure 300, may reveal a gloss value of from about 85 to about 95 units. In yet another example, the enclosure 300, may reveal a gloss value of about 92 units. In an example, the enclosure 300, of the present disclosure may have a tensile strength of from about 290 MPa to about 700 MPa as measured by American Society for Testing and Materials (ASTM) D790. In another example, the enclosure 300 of the present disclosure may have a tensile strength of from about 250 MPa to about 600 MPa as measured by the American Society for Testing and Materials (ASTM) D790. In yet another example, the enclosure 300, of the present disclosure may have a tensile strength of from about 350 MPa to about 600 MPa as measured by American Society for Testing and Materials (ASTM) D790.

[0966] Fig. 4 Illustrates a sectional view of an enclosure 400, for an electronic device comprising at least one decorative layer on the electrophoretic deposition layer 406, according to an example of the present disclosure.

[0067] Referring to Fig. 4, an enclosure comprises a metal frame comprising at least one aluminum alloy region 492, and at least one magnesium alloy region 404; at least one passivation layer 410, an electrophoretic deposition layer 406, on at least a passivated junction interface 414, of the at least one aluminum alloy region and the at least one magnesium alloy region; at least one decorative layer 412 on the electrophoretic deposition layer; and an anodic layer 408, on at least a chamfered portion of the aluminum alloy region.

[0068] The sectional view of the enclosure 400, comprises at least one passivation layer 410, which is present on the at least one aluminum alloy region 402, and the at least one magnesium alloy region 404, and at least a junction interface 414, of the at least one aluminum alloy region and the at least one magnesium alloy region. In an example, the passivation layer 419, on the at least one aluminum alloy region results in the formation of passivated aluminum alloy region. The enclosure also comprises an electrophoretic deposition layer 406, on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region; and an anodic layer on at least a chamfered portion of the aluminum alloy region, in an example, the electrophoretic deposition layer 496, may be present on the at least one passivated aluminum alloy region. In another example, the electrophoretic deposition layer 408, may be present on the at least one passivated magnesium alloy region. The enclosure may have an anodic layer 408, on at least a chamfered portion of the aluminum alloy region.

[0069] In an example, file enclosure for an electronic device comprises a metal frame comprising at least one aluminum alloy region 402, and at least one magnesium alloy region 404; at least one passivation layer 410, an electrophoretic deposition layer 406, on at least a passivated Junction interface 414, of the at least one aluminum alloy region and the at least one magnesium alloy region; at: least one decorative layer 412 on the electrophoretic deposition layer and an anodic layer, 408 on at least a chamfered portion of the aluminum alloy region.

[0070] In an example, the aluminum alloy region 402, may be made up of an aluminum alloy selected torn AL575, AL1050, 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, AL5857, AL5754, AL6005, AL6005A, A16060, AL6061, AL6063, AL6066, AL6070, AL6082, AL6105, AL8151, AL8162, AL8205, AL8262, AL6351, AL6463, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079, AL7116, AL7129, AL7175, AL7475, AL7178, or combinations thereof. In an example, magnesium alloy region 404, may he made up of magnesium alloy selected from AZ63, AZ81, AZ91, AM50, AM60, AZ31, AZ61, AZ80, AE44, AJ62A, ALZ391 , AMCa602, LZ91, magnox, or combinations thereof.

[8071] In an example, the enclosure comprises a metal frame having a thickness of from about 0.3 mm to about 2.0 mm. In another example, the enclosure comprises a metal frame having a thickness of from about 0.5 to 1.8 mm. In yet another example, the enclosure comprises a metal frame having a thickness of 0.7 mm.

[0072] In an example, the enclosure comprises a Junction interface, which may be passivated by deposition of a passivation layer to obtain a passivated junction interface. The junction interface may be Interface wherein dissimilar metal alloys join, i.e., the junction between the at least one aluminum alloy region and the at least one magnesium alloy region. [0073] In an example, the enclosure comprises at least one passivation layer 410. The passivation layer may Pa deposited on the metal frame to obtain a passivated metal frame. In some examples, the passivation layer may be deposited on the aluminum alloy region or the magnesium alloy region or both. In another example, the passivation layer may be deposited on the junction interface of the aluminum alloy region and the magnesium alloy region to obtain the passivated junction interface 414. In an example, the passivated junction interface may be obtained by depositing the passivation layer by electro-chemical passivation treatment. The electrochemical passivation treatment may be a micro-arc oxidation process. In another example, the passivated junction interface may be obtained by depositing the passivation layer by a process of dip coating. The method of deposition may result in varied thickness ranges of the passivated junction interfac. In an example, the passivated junction interface may have a thickness of from about 1.0 μm to about 15.0 μm.

[0074] In an example, the passivated junction interface formed by electro- chemical passivation treatment may have a thickness of from about 2.0 μm to about 15.0 μm. In another example, the passivated junction interface formed by electro-chemical passivation treatment may have a thickness of from about 3,0 μm to about 12.0 μm. In yet another example, the passivated function interface formed by electro-chemical passivation treatment may have a thickness of from about 3.0 μm to about 7.0 μm.

[0075] In an example, the passivated junction interface formed by the process of dip coating may have a thickness of from about 1.0 μm to about 5.0 μm. In another example, the passivated junction Interface formed by the process of dip coating may have a thickness of from about 1.5 μm to about 3.0 μm. The passivation layer on the metal frame may prohibit oxidation at the surface of the metal alloys.

[0076] In an example, the enclosure comprises electrophoretic deposition layer 406, on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region. The electrophoretic deposition layer 406 may seal the junction gap or voids (fill and seal small surface pits and interconnected subsurface porosity) on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region. The electrophoretic deposition layer may prevent the penetration of putty agents, primer paint, and/or anodizing chemicals, which may cause reliability issues and delamination on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region. The electrophoretic deposition layer 406, coated on at least a passivated Junction Interface of the at least one aluminum alloy region and the at least one magnesium alloy region may provide decorative effects (decorative finish), corrosion protection (form a protective barrier against environment exposure), bonding enhancement in the Junction area. In an example, the electrophoretic deposition layer 406 may be transparent. Various kinds of copolymers may be employed while coating the electrophoretic deposition layer. The copolymers may be selected from polyacryiate copolymer, polyacrylic, epoxy, polyacrylamide-acrylic, and combinations thereof, in an example, the electrophoretic deposition layer 406 may comprise copolymers of polyacryiate. In another example, the electrophoretic deposition layer 406 may comprise copolymers of polyacrylamide-acrylic. The acrylic type electrophoretic deposition layer may be transparent and may also fill and seal small surface pits and interconnected subsurface porosity on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region.

[0077] In an example, the electrophoretic deposition iayer 406 on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region, may have a thickness of from about 5.0 μm to about 30.0 μm. In another example, the electrophoretic deposition layer 406 may have a thickness of from about 6.0 μm to about 25.0 μm. In yet another example, the electrophoretic deposition layer 406 may have a thickness of from about 10.0 μm to about 25.0 μm. In some examples, the electrophoretic deposition layer 406 may have a thickness of from about 15.0 μm to about 20.0 μm. In another example, the electrophoretic deposition layer 406 may have a thickness of about 15.0 μm. POTS] The at least one decorative layer 412 may have a thickness of from about 5.0 μm to about 70.0 μm. In another example, the at least one decorative layer 412, may have a thickness of from about 10.0 μm to about 68.0 μm. In yet another example, the at least one decorative layer 412, may have a thickness of from about 10.0 μm to about 65.0 μm.

[0079] In another example, the at least one decorative layer may be a single layer or may comprise multiple layers, such as primer coat, base coat, and top coat.

[0080] In an example, the at least one decorative layer comprises sequentially 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, [0081] In an example, the at least one decorative 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.

[0082] The at least one decorative layer may comprise a base coat, in combination with additional layers. The base coat may 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, tie 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 includes polyurethane containing clay.

[0083] In an example, the base ccat may be coated on a primer coat of the at least one decorative layer.

[0084] The at least one decorative layer may comprise a 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 electrophoretic deposition layer. In another example, the top coat may be coated on the base coat of the at least one decorative layer. In yet another example, the top coat may be coated on the primer coat of the at least am decorative layer.

[0086] 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.

[0086] In an example, the top coat may be made of polyacrylic, polyurethane, urethane acrylates, acrylic acrylates, epoxy acrylates, or combinations thereof. In another example, the top coat may be made of polyacrylic. In yet another example, the top coat may be made of polyurethane. In some examples, the top coat may be made of urethane acrylates.

[0087] In an example, the at least one decorative layer may comprise primer coat, in combination with additional layers. The primer coat may be applied as single or multiple coats to achieve the desired thickness and finish, in an example, the primer coat may have a thickness of from about 5.0 μm to about 20.0 μm. In another example, the primer coat may have a thickness of from about 8.0 μm to about 18.0 μm. In yet another example, the primer coat may have a thickness of about 12.0 μm. In an example, the primer coat may be coated on the electrophoretic deposition layer.

[0088] The enclosure for an electronic device may have defects at the edges. To eliminate the defects and to obtain high gloss finish at the edges/sides of the enclosure, the first metal substrate 402, may be chamfered. The chamfering may be carried out at portions of the enclosure where a different aesthetic appeal is to be provided as compared to the rest of the enclosure, such as cover edge, touchpad, dick-pad, fingerprint scanner, edge, sidewall, hinge cap, area where the logo is to be provided, and the like. Chamfering may involve abrasive removal of edge material and eventually may provide even surface at the edges with the desired finish and enhanced strength. [0089] In an example, the enclosure comprises an anodic layer 408, on at least a chamfered portion of trie aluminum alloy region 402. The anodic layer 408 may provide high gloss finish at chamfered portions and may enhance the natural corrosion resistance of the aluminum alloy region 402. The anodic layer may be deposited on the chamfered portions by an electrochemical process that converts aluminum alloy into Its oxide form. 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. The thickness of the anodic layer may be increased to develop a wear-resistant hard coat.

[0090] In an example, the anodic layer 408 may have a thickness of from about 7.0 μm to about 15.0 μm. In another example, the anodic layer 408 may have a thickness of from about 8,0 μm to about 12.0 μm. In yet another example, the anodic layer 408 may have a thickness of from about 8.0 μm to about 10.0 μm. In some examples, the anodic layer 408 may have a thickness of about 9.0 μm. In an example, the anodic layer described herein, may in addition to protection, also cosmetically enhance the look and feel of chamfered edges of the enclosure for 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.

[0091] The aesthetic quality of thus obtained enclosure 400, may be quantified by measuring a gloss value. The gloss value of the enclosure for an electronic device may be of from about 80 units to about 100 units as measured by the American Society for Testing and Materials (ASTM) D523 at a viewing angle of about 60°, In another example, the enclosure 400, may reveal a gloss value of from about 85 to about 95 units. In yet another example, the enclosure 400, may reveal a gloss value of about 92 units. In an example, the enclosure 400, of the present disclosure may have 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, the enclosure 400, of the present disclosure may have 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, the enclosure 400, of the present disclosure may have a tensile strength of from about 350 MPa to about 600 MPa as measured by American Society for Testing and Materials (ASTM) D790,

[0092] Fig. 5 illustrates a method of forming an enclosure 500 for an electronic device, according to an example of the present disclosure. Block 502 Illustrates pre-forming an aluminum alloy part. The aluminum alloy may be selected from AL575. AL1050, AL1060, AL1100, AL1199, AL2014, AL2024, AL2218, AL3004, AL4041 , AL5005, AL5010, AL5019, AL5024, AL5026, AL5050, AL5052, AL5056, AL5059, AL5053, AL5086, AL5154, AL5182, AL5252, AL5254, AL5356, AL5454, AL5456, AL5457, AL5557, AL5652, AL5657, AL5754, AL6005, AL6005A, AL6060, AL6061, AL6063, AL6066, AL6070, AL6082, AL6105, AL6151, AL6162, AL6205, AL6262, AL6351 , AL6463, AL7005, AL7022, AL7068, AL7072, AL7075, AL7079. AL7116, AL7129, AL7175, AL7475, AL7178, or combinations thereof. The aluminum alloy may be heated to form a semi-solid slurry, and then this slurry may be forged, stamped, CNC forged, CNC stamped to pre-form the aluminum alloy to form a part. Injection-molding a magnesium alloy on to at least a portion of the part is represented by block 504 of the Fig. 5. In an example, the part may be placed in a mold followed by injection-molding a magnesium alloy on to at least a portion of the part to obtain a metal frame comprising at least one junction interface. Magnesium alloy may be injection- molded at least partially around the part formed of aluminum alloy, thereby obtaining a metal frame comprising at least one aluminum alloy region and at least one magnesium alloy region with a junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region. In an example, the injection-molding may be carried out an injection pressure of from about 56 MPa to about 150 MPa, The injection speed may be from about 40 rμm to about 200 rpm, and the mold temperature may be from about 200 °C to about 500 °C. In an example, the injection-molding may be carried out at a temperature of from about 250 °C to about 450 °C. In another example, tbe injection-molding may be carried out at a temperature of from about 250 °C to about 400 °C. In yet another example, the Injection-molding may be carr ied out at a temperature of from about 300 °C to about 400 °C.

[0093] Block 506, of Fig. 5 Illustrates depositing a passivation layer on to the metal frame. The deposition of passivation layer results in the formation of a passivated metal frame. The method for forming an enclosure comprises depositing a passivation layer on to the metal frame to obtain a passivated metal frame. The passivated metal frame may be obtained by depositing a passivation layer on to metal frame or at the Junction interface of the aluminum alloy and magnesium alloy. Deposition of the passivation layer may be carried out by a process selected from chemical passivation treatment, electro-chemical passivation treatment or combinations thereof. The metal frame may be degreased, cleaned, polished, or neutralized before depositing the passivation layer.

[0094] In an example, depositing the passivation layer may be carried out by electrochemical passivation treatment to obtain a passivated metal frame. The electrochemical 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 2.0 μm to about 15.0 μm. In another example, the passivation layer formed by micro-arc oxidation may have a thickness of from about 3.0 μm to about 12.0 μm. In yet another example, the passivation layer formed by micro-arc oxidation may have a thickness of from about 3.0 μm to about 7.0 μm.

[0095] In an example, depositing the passivation layer on to the metal frame carried out by electrochemical 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, fluoro- 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 he employed at a dosage of from about 0.05% to about 15% in the presence of water at a pH of from about 9 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.

|009b] in another example, depositing a passivation layer on to the metal frame may be carried out by chemical passivation treatment to obtain a passivated metal frame, i.e., process of dtp coating for a period of from about 20 seconds to about 120 seconds, in an example, depositing a passivation layer on to the metal frame 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 1.0 μm to about 5.0 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.

[0097] In an example, the dip coaling 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 the 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 the total weight of the aqueous solution.

[0098] As shown in Block 508 of Fig. 5 coating an electrophoretic deposition (ED) layer may be done on to the passivated metal frame to obtain a coated metal frame. The thickness of the ED layer achieved may be directly related to the potential applied and time for the electrophoretic deposition, in an example, the coating the electrophoretic deposition layer on to the passivated metal frame may be carried out by applying a potential of from about 30 to about 150 V for a period of from about 20 to about 120 seconds. In another example, coating the electrophoretic deposition layer may be carried out by applying a potential of from about 50 to about 130 V for a period of from about 20 to about 100 seconds, in yet another example, the coating the electrophoretic deposition layer may be carried out by applying a potential of about 120 V for a period of about 80 seconds. In an example, coating the electrophoretic deposition layer on to the passivated metal frame is carried out to cover the Junction interface.

[0099] In an example, the electrophoretic deposition layer may seal the Junction gap or voids (fill and seat small surface pits and interconnected subsurface porosity) on the passivated metal frame to obtain a coated metal frame. The electrophoretic deposition layer may prevent the penetration of putty agents, primer paint, and or anodizing chemicals, which may cause reliability issues and delamlnation on the passivated metal frame. The electrophoretic deposition layer coated on to the passivated metal frame may provide decorative effects (decorative finish), corrosion protection (form a protective barrier against environment exposure), or bonding enhancement in the junction area. In an example, the electrophoretic deposition layer may be transparent Various kinds of copolymers may be employed while coating the electrophoretic deposition layer. The copolymers may be selected from polyacrylate copolymer, polyacrylic, epoxy, polyacrylamide-acrylic, and combinations thereof. In an example, the electrophoretic deposition layer may comprise copolymers of polyacrylate, In another example, the electrophoretic deposition layer may comprise copolymers of polyacrylamide-acrylic. The acrylic type electrophoretic deposition layer may be transparent and may also fill and seal small surface pits and interconnected subsurface porosity at the passivated metal frame.

[00100] In an example, the electrophoretic deposition layer may have a thickness of from about 5.0 μm to about 30.0 μm. in another example, the electrophoretic deposition layer may have a thickness of from about 6.0 μm to about 25.0 μm. In yet another example, the electrophoretic deposition layer may have a thickness of from about 10.0 μm to about 25 μm. In some examples, the electrophoretic deposition layer may have a thickness of from about 15.0 μm to about 20 μm. In another example, the electrophoretic deposition layer may have a thickness of about 15.0 μm. [00101] In an example, at least one decorative layer may be deposited on to the coated metal frame to obtain a decorated metal frame. The method for forming an enclosure for an electronic device may comprise depositing at least one decorative layer on to the coated metal frame. The decorative layer may be deposited on to the electrophoretic deposition layer to obtain a decorated metal frame. In an example, the coating of at least one decorating iayer may be carried out by spray coating.

[00102] In an example, the at ieast one decorative Iayer may have a thickness of from about 5.0 μm to about 70.0 μm. In another example, the at least one decorative Iayer may have a thickness of from about 10.0 μm to about 68.0 μm. in yet another example, the at least one decorative layer may have a thickness of from about 10.0 μm to about 65.0 μm.

[00103] The coating at least one decorative layer on to the coated metal frame carried out by spray coating may be carried out in a manner, whereby the at least one decorative layer thus formed may comprise multipie layers, such as primer, base coat, and top coat. In an example, the spray-coated decorative 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.

[00104] In an example, the spray-coated decorative layer comprises sequentially deposited exists of 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.

[00105] The electrophoretic deposition Iayer may be cleaned, dried, degreased, and washed before the coating of the at least one decorative layer. The at Ieast one decorative 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 6.0 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. [00108] In an example, the primer may be coated on the metal frame or the coated metal frame by spray coating polyurethanes followed by beat treatment at a temperature of from about 60 °C to about 80 °C for a period 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 °C for a period 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.

[00107] The at least one decorative 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. 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.

[00108] In another example, the base coat coated by spray coating may be followed by heat treatment at a temperature of from about 80 °C to about 80 °C for a period 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 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. [00109] The at least one decorative 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 coated metal frame.

[00110] In an examp,le 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.

[00111] In an example, the top coat may be made of polyacrylic, polyurethane, urethane acrylates, acrylic acrylates, epoxy acrylates, or combinations thereof. In another example, the top coat may be made of polyacrylic. In yet another example, the top coat may be made of polyurethane. In some examples, the top coat may be made of urethane acrylates.

[00112] In an example, the top coat coated by spray coating may be followed by UV treatment of from about 700 mJ/cm² to about 1200 mJ/cm² for a period from about 10 seconds to about 30 seconds. In another example, the top coat coated by spray coating may be followed by UV treatment of from about 800 mJ/cm² to about 1100 mJ/cm² for a period 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 mJ/cm² for a period of about 20 seconds. [00113] 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 °C for a period 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 °C for a period 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.

[00114] Chamfering at least a portion of the part may be carried out, as shown in Block 510 of the Fig. 5. Chamfering at least one portion of the part results in the formation of a chamfered metal frame. In an example, chamfering at least the portion of the part of the enclosure includes chamfering at areas selected from the group consisting of enclosure edge, touchpad, fingerprint scanner, click-pad, sidewall, logo, hinge cap, and combinations thereof. 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 machin. In another example, the chamfering may be carried out with a CNC diamond cutting machine at speed of from about 5000 to about 90000 rpm 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 8000 to about 80000 rpm.

[0011 SJ The chamfered metal frame may be cleaned, degreased, washed and dried, prior to anodizing. 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 earned out by ultrasonic degreasing methods to remove impurities, such as fat, grease, or oil from the surface of the chamfered metal frame.

[00118] In an example, the chamfered portions of the chamfered metal frame may be anodized to form an enclosure for an electronic device, i.e., comprising an anodic layer over the chamfered portion. Forming anodic layers protect and cosmetically enhance metal surfaces is described. Anodizing the chamfered metal frame, as shown in Block 512 of the Fig. 5, permits an underlying metal surface to be viewable. For instance, the coated metal frame after chamfering may form features that may help form patterns and logos on the metal surfaces. In an example, anodizing the chamfered metal frame may be carried out in the 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 °C to about 50 °C. In another example, anodizing the chamfered metal frame may be carried out in the 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 yet another example, anodizing the chamfered metal frame may be carried out in the presence of 150-200 g/L of at feast 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 selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, or combinations thereof.

[00117] In an example, the anodizing the chamfered metal frame 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 10.0 μm. The thickness of the anodic layer achieved may be directly related to the potential applied and time employed in the process of anodizing.

[00118] The method of anodization, as described herein, may, in addition to protection, also cosmetically enhance the look and feel of chamfered metal surfaces of electronic devices. The anodic layer formed after the anodizing of the chamfered metal frame may be transparent, which reveals 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.

[00119] For instance, molten magnesium alloy can be injected info a mold to become part of the frame, to obtain a metal frame. Upon cooling, the metal frame can be removed from the mold, and a component of the desired shape may be removed.

[00120] In an example, the metal composite cover/enclosure 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 metal composite cover/enclosure may be used as a body or frame for keyboards of computers or laptops.

[00121] 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, instead, the specific features and methods are disclosed and explained as examples of the present disclosure.

Claims

We Claim: 1. A metal composite cover for an electronic device, the cover comprising; a metal frame comprising a first metal alloy substrate and an Injection- molded second metal alloy substrate adjacent to the first metal alloy substrate; an electrophoretic deposition layer on the metal frame; and an anodic layer on at least a chamfered portion of the first metal alloy substrate.

2. The metal composite cover of claim 1, wherein the first metal alloy substrate is made of aluminum alloy and the injection-molded second metal alloy substrate Is made of magnesium alloy.

3. The metal composite cover of claim 1, wherein the electrophoretic deposition layer has a thickness of from about 5.0 μm to about 30.0 μm.

4. The metal composite cover of claim 1, wherein the anodic layer has a thickness of from about 7.0 μm to about 15.0 μm.

5. The metal composite cover of claim 1 , comprising at least one passivation layer on the metal frame.

6. An enclosure for an electronic device, the enclosure comprising: a metal frame comprising at least one aluminum alloy region and at least one magnesium alloy region; an electrophoretic deposition layer on at least a passivated junction interface of the at least one aluminum alloy region and the at least one magnesium alloy region; and an anodic layer on at least a chamfered portion of the aluminum alloy region.

7. The enclosure of claim 6, wherein the metal frame has a thickness of from about 0.3 mm to about 2.0 mm.

8. The enclosure of claim 6, wherein the passivated junction interface has a thickness of from about 1.0 μm to about 15.0 μm.

9. The enclosure of claim 6, comprising at least one decorative layer on to the electrophoretic deposition layer.

10. A method for forming an enclosure for an electronic device, the method comprising: pre-forming an aluminum alloy to form a part; injection-molding a magnesium alloy on to at least a portion of the part to obtain a metal frame comprising at feast one junction Interface; depositing a passivation layer on to the metal frame to obtain a passivated metal frame; coating an electrophoretic· deposition layer on to the passivated metal frame to obtain a coated metal frame; chamfering at least one portion of the part to obtain chamfered metal frame; and anodizing the chamfered metal frame to form an enclosure for an electronic device.

11. The method of claim 10, wherein coating the electrophoretic deposition layer on to the passivated metal frame is carried out to cover the junction interface.

12. The method of claim 10, wherein injection-molding a magnesium alloy on to at least the portion of the part to obtain metal frame is carried out at a temperature of from about 200 °C to about 500 °C

13. The method of claim 10, comprises depositing at least one decorative layer on to the coated metal frame to obtain a decorated metal frame.

14. The method of claim 10, wherein anodizing the chamfered metal frame is 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 °C to about 50°C.

15. The method of claim 10, wherein chamfering at feast the portion of the part includes chamfering at areas selected from the group consisting of enclosure edge, touchpad, fingerprint scanner, click-pad , sidewall, logo, hinge cap, and combinations thereof.