WO2022050948A1

WO2022050948A1 - Housings for electronic devices

Info

Publication number: WO2022050948A1
Application number: PCT/US2020/049311
Authority: WO
Inventors: Yong-jun LI; Ya Cheng Chuang; Kuan-Ting Wu
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-09-04
Filing date: 2020-09-04
Publication date: 2022-03-10

Abstract

An anti-corrosive metal housing for an electronic device can include a metal substrate, a passivation layer, and a sealing layer. The passivation layer can include an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof. The sealing layer can include sodium silicate, aluminum powder, zinc powder, graphene powder, clay powder, or a combination thereof.

Description

HOUSINGS FOR ELECTRONIC DEVICES

BACKGROUND

[0001 ] The use of electronic devices of all types continues to increase. Cellular phones (including smart phones), tablet computers, desktop computers, and laptop computers are used by many for personal, entertainment, and/or business purposes. Electronic devices have become a staple product of modern life. Electronic devices typically include some type of housing. As the use of electronic devices continues to rise, so does the demand for the development of housings for electronic devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] FIG. 1 graphically illustrates an example anti-corrosive metal housing for an electronic device in accordance with the present disclosure;

[0003] FIG. 2 graphically illustrates an example anti-corrosive metal housing for an electronic device in accordance with the present disclosure;

[0004] FIG. 3 graphically illustrates an example electronic device in accordance with the present disclosure; and

[0005] FIG. 4 is a flow diagram illustrating an example method of applying an anti-corrosion treatment to a metal substrate in accordance with the present disclosure.

DETAILED DESCRIPTION

[0006] Electronic devices incorporate housings to encase and protect the electronic components of the electronic device. These housings can be manufactured from various materials and can include decorative finishes to increase aesthetic appeal. In some examples, an after-market decorative finish, such as paint, can be applied over an exterior surface of the substrate; however, application of after-market finishes can be difficult to apply evenly or neatly in some instances because the device is already assembled and may need to be masked or otherwise prepared for a typically more complicated finishing process. Furthermore, some substrates may have poor color stability, may be susceptible to corrosion, and may be resistant to some finishes.

[0007] In accordance with examples of the present disclosure, an anti-corrosive metal housing for an electronic device is presented. The anti-corrosive metal housing for an electronic device can include a metal substrate; a passivation layer that can include an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof; and a sealing layer that can include sodium silicate, aluminum powder, zinc powder, graphene powder, clay powder, or a combination thereof. In an example, the metal substrate can further include a paint coating. The paint coating can include a primer layer, a basecoat layer, a topcoat layer, an anti-fingerprint layer, or a combination thereof. In another example, the metal substrate can have a density ranging from about 0.5 g/cm³ to about 9 g/cm³ and the metal substrate can be selected from aluminum, magnesium, lithium, titanium, zinc, niobium, mixtures, or alloys thereof. In yet another example, a thickness of the passivation layer can be from about 1 pm to about 5 pm and a thickness of the sealing layer can be from about 0.5 pm to about 5 pm. In a further example, the metal substrate can further include an inner surface and the inner surface can have an inner passivation layer and an inner sealing layer formed thereon. The inner passivation layer can include an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof, and the inner sealing layer can include sodium silicate, aluminum, zinc, graphene, clay or a combination thereof.

[0008] Also presented herein is an electronic device. The electronic device can include an electronic component of the electronic device and an anti-corrosive metal housing to support the electronic components. The anti-corrosive metal housing can include a metal substrate, a passivation layer, and a sealing layer. The passivation layer can include an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof. The sealing layer can include sodium silicate, aluminum powder, zinc powder, graphene powder, clay powder, or a combination thereof. In an example, the metal housing can be shaped as a housing of a laptop, a desktop computer, a smartphone, a tablet, a printer, a monitor, a keyboard, a pair of headphones, a television, a speaker, a docking station, a webcam, a smart watch, a calculator, or a combination thereof. In another example, the metal substrate can have an average thickness from about 0.3 mm to about 2 mm, the passivation layer can have an average thickness from about 1 pm to about 5 pm, and the sealing layer can have an average thickness from about 0.5 pm to about 3 pm. In yet another example, the metal housing can further include a paint coating. The paint coating can include a primer layer, a basecoat layer, a topcoat layer, an anti-fingerprint layer, or a combination thereof.

[0009] Further presented herein, in an example, is a method of applying an anti-corrosion treatment to a metal substrate of a housing for an electronic device. The method can include treating a metal substrate in an aqueous oxyanion passivation bath to form a passivated metal substrate, where the oxyanion passivation bath can include from about 3 wt% to about 15 wt% molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof; and treating the passivated metal substrate with an aqueous sealing dispersion to form the metal substrate with the anti-corrosion treatment thereon, where the sealing dispersion can include from about 5 wt% to about 30 wt% sodium silicate, aluminum powder, zinc powder, or a combination thereof and from about 0.1 wt% to about 3 wt% graphene powder, clay powder, or a combination thereof. In one example, the sealing dispersion can include the sodium silicate at from about 20 wt% to about 25 wt%, and the aluminum powder, the zinc powder, or a combination thereof at from about 2 wt% to about 5 wt%. In another example, the graphene powder, the clay powder, or the combination thereof can have an average particle size ranging from about 0.1 pm to about 10 pm. In yet another example, the method can further include degreasing the metal substrate in a degreasing solution prior to the treating of the metal substrate in the oxyanion passivation bath. The degreasing solution can include from about 0.3 wt% to about 2 wt% sodium caseinate, sodium polyacrylate, sodium polyoxyethylene alkyl ether carboxylate, sodium dodecyl sulfate, or a combination thereof. In a further example, the method can include spray coating the metal substrate following treatment with the sealing dispersion with a primer formulation, a basecoat formulation, a topcoat formulation, an anti-fingerprint layer, or a combination thereof, and UV curing the primer formulation, the basecoat formulation, the topcoat formulation, the anti-fingerprint layer, or the combination thereof with a UV light source at from about 700 mJ/cm² to about 1 ,200 mJ/cm² to polymerize polymers in the primer formulation, the basecoat formulation, the topcoat formulation, the anti-fingerprint layer, or the combination thereof. In one example, the method can include coating with the topcoat formulation. The topcoat formulation can include a first topcoat and a second topcoat. The first topcoat can include from about 30 wt% to about 65 wt% polyester, acrylic, polyurethane, copolymers, or admixtures thereof, and the second topcoat can include from about 50 wt% to about 80 wt% polyacrylic, polyurethane, urethane acrylates, acrylic acrylates, epoxy acrylates, copolymers, or admixtures thereof.

[0010] It is noted that when discussing the anti-corrosive metal housing for an electronic device, the electronic device, and/or the method of applying an anti-corrosion treatment to a metal substrate of a housing for an electronic device herein, these discussions can be considered applicable to one another whether or not they are explicitly discussed in the context of that example. Thus, for example, when discussing a substrate related to an anti-corrosive metal housing for an electronic device, such disclosure is also relevant to and directly supported in the context of the electronic device, the method of applying an anti-corrosion treatment to a metal substrate of a housing for an electronic device, and vice versa.

[0011 ] It is also understood that terms used herein will take on the ordinary meaning in the relevant technical field unless specified otherwise. In some instances, there are terms defined more specifically throughout the specification or included at the end of the present specification, and thus, these terms can have a meaning as described herein.

Anti-Corrosive Metal Housings for Electronic Devices [0012] Anti-corrosive metal housings for electronic devices, also referred to herein as “housing(s),” can have a variety of configurations which can be determined in part by the electronic device and the electric component that may be associated with the housing. For example, the housing can be a laptop housing, a desktop computer housing, a smartphone housing, a tablet housing, a printer housing, a monitor housing, a keyboard housing, a headphones housing, a television housing, a speaker housing, a docking station housing, a webcam housing, a smart watch housing, or a calculator housing, and can thus be shaped accordingly to efficiently (in some instances) provide a protective cover to the underlying electronics.

[0013] In examples herein, the anti-corrosive metal housing can include a metal substrate that can be covered in a passivation layer and a sealing layer. An example anti-corrosive metal housing 100 for an electronic device is shown in FIG. 1 , and can include a metal substrate 102 and a passivation layer 110 on the substrate. The passivation layer can include an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof. The housing can further include a sealing layer 120 on the passivation layer, and can include sodium silicate, aluminum powder, zinc powder, graphene powder, clay powder, or a combination thereof.

[0014] In further detail, a substrate 102 of the housing 100 can be shaped in the form of a housing for an electronic device (not shown, but shown in FIG. 3 by way of example). The substrate can include a metal, such as a metal selected from aluminum, magnesium, lithium, zinc, titanium, niobium, or mixtures or alloys thereof. In another example, the substrate can include a metal and the metal can include aluminum, magnesium, or alloys thereof. A density of the substrate can range from about 0.5 g/cm³ to about 9 g/cm³, about 2 g/cm³ to about 8 g/cm³, or about 3 g/cm³ to about 9 g/cm³.

[0015] A thickness of the substrate 102 can vary depending on the intended housing type. For example, a thickness of a substrate that is designed for portable use such as a housing for a tablet or a cell phone may be thinner than a thickness of a housing for a product that is designed to be stationary such as a housing for a desktop computer or a printer. In some examples, the substrate can have a thickness from about 0.3 m to about 2 mm. In yet other examples, the substrate can have a thickness that can range from about 100 pm to about 500 pm, about 500 pm to about 1 ,500 pm, about 1 mm to about 2 mm, about 200 pm to about 1 ,200 pm, or about 0.5 pm to about 250 pm.

[0016] The passivation layer 110 can include an oxyanion deposited on a surface of the metal substrate 102. The oxyanion can be selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof. These oxyanions can form an ionic bond with a metal of the surface of the substrate. In an example, the passivation layer can have a thickness that can range from about 1 pm to about 5 pm, from about 2 pm to about 4 pm, from about 1 pm to about 3 pm, or about 3 pm to about 5 pm. In some examples, the passivation layer can be located on one surface or two surfaces of the metal substrate. For example, an outer passivation layer can be located on an outer surface of the metal substrate and an inner passivation layer can be located on an inner surface of the metal substrate.

[0017] The sealing layer 120 can be located on the passivation layer 110. The sealing layer can interact and bond with the passivation layer. A sealing layer can include sodium silicate, aluminum powder, zinc powder, graphene powder, clay powder, or a combination thereof. In some examples, a sealing layer can include sodium silicate. In other examples, a sealing layer can include sodium silicate, aluminum powder, zinc powder, or a combination thereof. In an example, the sealing layer can have a thickness that can range from about 0.5 pm to about 5 pm, from about 2 pm to about 4 pm, from about 1 pm to about 3 pm, from about 0.5 pm to about 2.5 pm, or from about 2.5 pm to about 5 pm.

[0018] As illustrated in FIG. 2, an anti-corrosive metal housing 105 can likewise include a metal substrate 102, with passivation layers 110A, 110B and sealing layers 120A, 120B applied on both sides of the metal substrate. For example, the sealing layers may be located over a passivation layer on the metal substrate. In this example, the sealing layer may include an outer sealing layer 120A and an inner sealing layer 120B. For example, an outer sealing layer may be located on an outer passivation 110A layer which may be located on an outer surface 106 of the metal substrate and an inner sealing layer may be positioned on an inner passivation layer which may be located on an inner surface 104 of the metal substrate. The terms “outer” and “inner” are relative terms to one another, but can be used for convenience to describe the surfaces closer to the electronic components to be housed (inner) or the surfaces closer to the exterior of the electronics device housing more distal to the electronics device to be housed (outer).

[0019] In some examples, the housing can further include a paint coating 130. The paint coating may be positioned over the sealing layer 120A. However it is noted that there may be a paint coating on both sides in some examples, and furthermore, the example shown at FIG. 1 may also similarly include a paint coating applied on the sealing layer. The paint coating can be a single coating or can include multiple coatings. The paint coating may include a primer layer, a basecoat layer, a topcoat layer, an anti-fingerprint layer, or a combination thereof. The paint coating may include multiple applications of a primer formulation, a basecoat formulation, a topcoat formulation, an anti-fingerprint formulation, or a combination thereof. The paint coating may also include multiple alternating layers of these formulations.

[0020] An amount of paint coating formulation(s) applied on the sealing layer can determine a thickness of the paint coating. In some examples, the paint coating can have a thickness from about 5 pm to about 65 pm, from about 5 pm to about 20 pm, from about 5 pm to about 40 pm, from about 20 pm to about 45 pm, or from about 50 pm to 65 pm. When present, the primer layer can have a thickness of from about 5 pm to about 20 pm; the basecoat layer can have a thickness of from about 10 pm to about 20 pm; the topcoat layer can have a thickness of from about 10 pm to about 25 pm; and an anti-fingerprint layer can have a thickness of from about 30 nm to about 1 pm. Further details on the paint coating formulations that may be applied to form the paint coating are described in further detail below.

[0021 ] The housing can be durable and corrosion resistant. In some examples, the corrosion resistance at a location of the sealing layer or a paint coating can pass an about 96 hour salt fog test, an about 100 hour salt fog test, an about 110 hour salt fog test, or an about 120 hour salt fog test. A metal substrate with a passivation layer thereon and excluding a sealing layer may pass 12 hour salt fog test, but in many instances, not salt fog tests of longer lengths, for example.

[0022] A salt fog test can involve exposing the substrate to an about 5 wt% salt solution for a period of time established by the test, e.g., about 12 hours, about 96 hours, about 100 hours, about 110 hours, or about 120 hours. The salt solution can be heated to from about 30 °C to about 40 °C and the test may be conducted according to the procedure specified in MIL-STD-81 OF. A housing may be considered as passing the salt fog test when there is no corrosion or failure of the anti-corrosion coating thereon. A housing may be considered as failing the salt fog test when there is suspected corrosion or failure of the coating thereon. The housings presented herein, in some examples, may have a metallic luster appearance or can have good color stability.

Electronic Devices

[0023] In examples herein, the anti-corrosive metal housing can include a substrate that is coated by the layers described in FIGS. 1 and 2, for example. For example, an electronic device 200 as shown in FIG. 3 can include the anti-corrosive metal housing 100 and an electronic component 205. The housing can include a metal substrate 102 that can have an interior surface 104 and an exterior surface 106. The exterior surface can include a passivation layer 110 and a sealing layer 120. An interior surface of the metal substrate can be adjacent to the electronic component of the electronic device. In some examples, a paint layer (not shown, but shown in FIG. 2) can be positioned on the sealing layer. An interior surface may also include a passivation layer, a sealing layer, and/or a paint layer (not shown, but shown in FIG. 2).

[0024] The electronic component can include any electric component of any electrical device. In some examples, the electronic component can include electronic components for a laptop, a desktop, a smartphone, a tablet, a printer, a monitor, a keyboard, a pair of headphones, a television, a speaker, a docking station, a webcam, a smart watch, a calculator, or the like. In some examples, the electronic device can be a laptop, a desktop, a smartphone, a tablet, a printer, a monitor, a keyboard, a pair of headphones, a television, a speaker, a docking station, a webcam, a smart watch, or a calculator. Thus, the housing can be a laptop housing, a desktop computer housing, a smartphone housing, a tablet housing, a printer housing, a monitor housing, a keyboard housing, a headphones housing, a television housing, a speaker housing, a docking station housing, a webcam housing, a smart watch housing, or a calculator housing, for example.

Methods of Applying an Anti-Corrosion Treatment Housings for Electronic Devices [0025] A flow diagram of an example method 300 of applying an anti-corrosion treatment to a metal substrate of a housing for an electronic device is shown in FIG. 4. The method can include treating 310 a metal substrate in an aqueous oxyanion passivation bath to form a passivated metal substrate. The oxyanion passivation bath can include from about 3 wt% to about 15 wt% molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof. The method can further include treating 320 the passivated metal substrate with an aqueous sealing dispersion to form the metal substrate with the anti-corrosion treatment thereon. The sealing dispersion can include from about 5 wt% to about 30 wt% sodium silicate, aluminum powder, zinc powder, or a combination thereof and from about 0.1 wt% to about 3 wt% graphene powder, clay powder, or a combination thereof dispersed therein.

[0026] In some examples, the method can further include degreasing a substrate in preparation for applying the anti-corrosion treatment. In yet other examples, the method can further include spray coating the metal substrate following treatment with the sealing dispersion with a primer formulation, a basecoat formulation, a topcoat formulation, an anti-finger print coating, or a combination thereof, and UV curing the primer formulation, the basecoat formulation, the topcoat formulation, the anti-fingerprint coating, or the combination thereof with a UV light source at from about 700 mJ/cm² to about 1 ,200 mJ/cm² to polymerize polymers in the primer formulation, the basecoat formulation, the topcoat formulation, the anti-finger print coating, or the combination thereof.

[0027] In further detail, the method may include degreasing the substrate. Degreasing can include submerging the substrate in a degreasing solution, rinsing the substrate, and allowing the substrate to dry after rinsing. The degreasing solution can include a sodium compound and water. The sodium compound can include sodium caseinate, sodium polyacrylate, sodium polyoxyethylene alkyl ether carboxylate, sodium dodecyl sulfate, or a combination thereof. The sodium compound can be present in the degreasing solution at from about 0.3 wt% to about 2 wt% or from about 0.5 wt% to about 1 .5 wt%. The degreasing solution can further include water. The water may be deionized. A pH of the degreasing solution may be adjusted with potassium hydroxide or sodium hydroxide to a pH ranging from about 9 to about 13.

[0028] The degreasing solution may be warmed to a temperature ranging from about 20 °C to about 60 °C. In other examples, the degreasing solution can be warmed to a temperature ranging from about 20 °C to about 25 °C, from about 20 °C to about 40 °C, from about 40 °C to about 60 °C, or from about 25 °C to about 50 °C. The substrate can be dipped in the degreasing solution for a period of time ranging from about 30 seconds to about 180 seconds, from about 30 seconds to about 60 seconds, from about 60 seconds to about 180 seconds, or from about 60 seconds to about 120 seconds. In some examples, the degreasing solution can be sonicated and from about 15 kHz to about 400 kHz, from about 200 kHz to about 400 kHz, or from about 15 kHz to about 250 kHz can be applied. Following submerging the substrate in the degreasing solution, the substrate can be rinsed with water or deionized water to remove the degreasing solution. In some examples, the submerging and/or rinsing can be repeated. The substrate may then be allowed to air dry before additional treatment.

[0029] The metal substrate may be treated in an oxyanion chemical bath to form a passivation layer on the metal substrate. The oxyanion chemical bath can include an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof. In one example, the oxyanion can include a manganese salt and the manganese salt can be selected from manganese sulfate, manganese chloride, manganese acetate, manganese carbonate, or a combination thereof. The oxyanion may be present in the oxyanion chemical bath at from about 3 wt% to about 15 wt%, from about 3 wt% to about 12 wt%, from about 5 wt% to about 15 wt%, from about 6 wt% to about 12 wt%, or from about 5 wt% to about 10 wt%. The oxyanion chemical bath can further include water. The water may be deionized.

[0030] The oxyanion chemical bath may be warmed to a temperature ranging from about 20 °C to about 50 °C. In other examples, the oxyanion chemical bath may be warmed to a temperature ranging from about 22 °C to about 45 °C, from about 25 °C to about 40 °C, or from about 30 °C to about 35 °C. The substrate can be submerged in the oxyanion chemical bath for a period of time ranging from about 20 seconds to about 120 seconds, from about 20 seconds to about 80 seconds, from about 60 seconds to about 120 seconds, or from about 40 seconds to about 100 seconds. The longer the substrate is submerged, the thicker the passivation layer formed thereon will be. The substrate may be allowed to air dry before additional treatment.

[0031 ] The passivated metal substrate may be treated with an aqueous sealing dispersion to form a sealing layer thereon. The aqueous sealing dispersion can include from about 5 wt% to about 30 wt% sodium silicate, aluminum powder, zinc powder, or a combination thereof. In yet other examples, the aqueous sealing dispersion can include from about 20 wt% to about 30 wt%, from about 5 wt% to about 25 wt%, from about 15 wt% to about 30 wt%, or from about 10 wt% to about 30 wt% sodium silicate, aluminum powder, zinc powder, or a combination thereof. In some examples, the aqueous sealing dispersion can include sodium silicate at from about 20 wt% to about 25 wt%, and the aluminum powder, the zinc powder, or a combination thereof at from about 2 wt% to about 5 wt%. In some examples, the sealing dispersion can further include graphene powder, clay powder, or a combination thereof at from about 0.1 wt% to about 3 wt%, from about 1 wt% to about 3 wt%, from about 0.5 wt% to about 1 .5 wt%, or from about 0.1 wt% to about 2 wt%.

[0032] Particles of the zinc powder, graphene powder, or clay powder in the aqueous sealing dispersion can have an average particle size ranging from about 0.1 pm to about 10 pm, from about 0.1 pm to about 4 pm, from about 5 pm to about 10 pm, or from about 2 m to about 8 pm. Average particle size can be measured using a particle analyzer such as the MASTERSIZER™ 3000 available from Malvern Panalytical (United Kingdom). The particle analyzer can measure particle size using laser diffraction. A laser beam can pass through a sample of particles and the angular variation in intensity of light scattered by the particles can be measured. Larger particles scatter light at smaller angles, while small particles scatter light at larger angles. The particle analyzer can then analyze the angular scattering data to calculate the size of the particles using the Mie theory of light scattering. The particle size can be reported as a volume equivalent sphere diameter. In further detail, particle size can be determined and/or confirmed using a scanning electron microscope (SEM). Particle size can be reported as a volume equivalent sphere diameter.

[0033] The sodium silicate, aluminum powder, zinc powder, graphene powder, clay powder, or a combination thereof can be dispersed in an aqueous liquid vehicle. The aqueous liquid vehicle can include water as the solvent. The water may be deionized. In some examples, a pH of the aqueous sealing dispersion may be adjusted. The adjustment can occur through an addition of potassium hydroxide, sodium hydroxide, or a combination thereof in an amount to adjust the pH to within the range of from about 8 to about 13.

[0034] The aqueous sealing dispersion may be warmed to a temperature ranging from about 20 °C to about 40 °C. In other examples, the aqueous sealing dispersion may be warmed to a temperature ranging from about 20 °C to about 30 °C, from about 25 °C to about 35 °C, or from about 30 °C to about 40 °C. The aqueous sealing dispersion may be circulated to prevent particles dispersed therein from settling. The substrate can be submerged in the aqueous sealing dispersion for a period of time ranging from about 60 seconds to about 120 seconds, from about 60 seconds to about 90 seconds, from about 90 seconds to about 120 seconds, from about 80 seconds to about 120 seconds, or from about 70 seconds to about 100 seconds. The longer the substrate is submerged in the aqueous sealing dispersion, the thicker the sealing layer formed on the substrate will be. In some examples, the substrate may be allowed to air dry before additional treatment. [0035] In some examples, the housing with the sealing layer thereon may be baked to remove water and impurities that may be present in the aqueous sealing dispersion and to minimize bubbling during drying. In some examples, the baking can occur in an oven at a temperature that can range from about 60 °C to about 120 °C, from about 60 °C to about 100 °C, from about 80 °C to about 120 °C, or from about 70 °C to about 90 °C. The baking can occur for a period of time ranging from about 10 minutes to about 30 minutes, from about 15 minutes to about 25 minutes, from about 10 minutes to about 20 minutes, or from about 20 minutes to about 30 minutes.

[0036] A paint coating may be spray coated over the sealing layer. The paint coating may include a primer layer, a basecoat layer, a topcoat layer, an anti-finger print layer, or a combination thereof. In some examples, the paint coating may include multiple applications of a formulation such as about 1 , about 2, about 3, or about 4 applications of the primer formulation; about 1 , about 2, about 3, or about 4 applications of the basecoat formulation; about 1 , about 2, about 3, or about 4 applications of the topcoat formulation; about 1 , about 2, about 3, or about 4 layers applications of an anti-finger print formulation or a combination thereof. The more applications, the thicker the paint coating will be.

[0037] A primer formulation can include a polymeric resin selected from an epoxy, epoxy-polyester, polyester, polyurethane, a polyurethane and polyurethane copolymer, epoxy-polyamide, or a combination thereof. The polymeric resin can be present at from about 20 wt% to about 60 wt%, from about 25 wt% to about 55 wt%, from about 28 wt% to about 50 wt%, or from about 30 wt% to about 45 wt%. The primer formulation may include water as the solvent. The primer formulation may further include biocide, thickener, defoamer, or a combination thereof.

[0038] A basecoat formulation can include a polymer selected from polyester, polyacrylic, polyurethane, polyurethane copolymer, polyester-imide, epoxy-polyamide, or a combination thereof. The polymer can be present at from about 20 wt% to about 60 wt%, from about 25 wt% to about 55 wt%, from about 28 wt% to about 50 wt%, or from about 30 wt% to about 45 wt%. The basecoat formulation can further include a colorant. The colorant can include a pigment, a dye, or both a pigment and a dye. The colorant may include any colorant combination to achieve the desired coloration. For example, the colorant can include a single pigment, multiple pigments, a single dye, multiple dyes, a single pigment and a single dye, multiple pigments and a single dye, a single pigment and multiple dyes, or multiple pigments and multiple dyes. In an example, the colorant may include a pigment and the pigment may be selected from azo pigments including diazo pigments and monoazo pigments; polycyclic pigments (e.g., phthalocyanine pigments such as phthalocyanine blues and phthalocyanine greens, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, pyranthrone pigments, and quinophthalone pigments); nitro pigments; nitroso pigments; anthanthrone pigments; or a combination thereof. In an example, the pigment may be selected from carbon black, titanium dioxide, clay, mica, talc, barium sulfate, calcium carbonate, a synthetic pigment, metallic powder, aluminum oxide, or a combination thereof. In another example, the colorant may include a dye and the dye may be selected from Alexa Fluor 594 dye, Texas Red, Pacific Blue dye, Pacific Orange, Quinoline Yellow WS, or a combination thereof. In some examples, no colorant may be present. When a colorant is present, the colorant may be present at from about 0.1 wt% to about 15 wt%, from about 0.3 wt% to about 10 wt%, or from about 0.5 wt% to about 8 wt%. The basecoat formulation may include water as the solvent. The basecoat formulation may in some examples further include biocide, thickener, defoamer, or a combination thereof.

[0039] A topcoat layer can be applied as a single formulation or as multiple formulations. In one example a topcoat layer may include a first topcoat and a second topcoat. The first topcoat can include a polymer selected from a polyester, acrylic, polyurethane, copolymers, or admixtures thereof. The polymer can be present at from about 30 wt% to 65 about wt%, from about 40 wt% to about 60 wt%, from about 30 wt% to about 45 wt%, or from about 45 wt% to about 55 wt%. The second topcoat can include a polymer selected from polyacrylic, polyurethane, urethane acrylates, acrylic acrylates, epoxy acrylates, copolymers, or admixtures thereof. The polymer can be present at from about 50 wt% to about 80 wt%, from about 50 wt% to about 75 wt%, from about 60 wt% to about 80 wt%, or from about 70 wt% to about 80 wt%. The topcoat formulations can include water as the solvent. The topcoat formulations may in some examples further include biocide, rheology modifier, matting agent, or a combination thereof.

[0040] An anti-finger print formulation may include from about 0.1 wt% to about 5 wt%, from about 0.1 wt% to about 3 wt%, or from about 2 wt% to about 4 wt% fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorourethanes, perfluoropolyethers, perfluoropolyoxetanes, fluorotelomers, polytetrafluoroethylenes (PTFE), polyvinylidenefluourides (PVDF), fluorosiloxanes, octyltrimethoxysilanes, dodecyldimethylchlorosilanes, long chain (C6 or more) silane polymers, or a combination thereof, dispersed in an aqueous liquid vehicle.

[0041 ] The paint coating formulations may be applied as a spray coating at a temperature ranging from about 60 °C to about 80 °C, from about 60 °C to about 70 °C, from about 70 °C to about 80 °C, or from about 65 °C to about 75 °C. A layer of the paint coating may be allowed to dry to the touch prior to successive applications. For example, a paint coating formulation may be allowed to air dry for about 10 minutes to about 40 minutes, about 15 minutes to about 30 minutes, about 10 minutes to about 25 minutes, or about 30 minutes to about 30 minutes.

[0042] In some examples, the housing with the paint coating thereon may be flash baked to assist in the evaporation of water and removal of residual chemicals that may be present in the paint formulations. In some examples, the baking can occur in an oven at a temperature that can range from about 50 °C to about 60 °C, from about 50 °C to about 55 °C, or from about 55 °C to about 60 °C. The baking can occur for a period of time ranging from about 3 minutes to about 15 minutes, about 4 minutes to about 13 minutes, about 5 minutes to about 12 minutes, or from about 7 minutes to about 10 minutes.

[0043] The paint coating can be cured using a UV light source that can emit energy in a range from about 700 mJ/cm² to about 1 ,200 mJ/cm², from about 800 mJ/cm²to about 1 ,200 mJ/cm², from about 700 mJ/cm² to about 900 mJ/cm², or from about 1 ,000 mJ/cm² to about 1 ,200 mJ/cm² UV light curing can polymerize polymers in the primer formulation, basecoat formulation, the topcoat formulation, the anti-fingerprint formulation, or a combination thereof. The UV light curing can occur for a time period ranging from about 10 seconds to about 30 seconds, about 15 seconds to about 30 seconds, about 10 seconds to about 20 seconds, or from about 20 seconds to about 30 seconds. In some examples, UV light curing can cross polymerize polymers in the paint coating.

Definitions

[0044] It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise.

[0045] The term "about" as used herein, when referring to a numerical value or range, allows for a degree of variability in the value or range, for example, within 10%, or, in one aspect within 5%, of a stated value or of a stated limit of a range. The term “about” when modifying a numerical range is also understood to include as one numerical subrange a range defined by the exact numerical value indicated, e.g., the range of about 1 wt% to about 5 wt% includes 1 wt% to 5 wt% as an explicitly supported sub-range.

[0046] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though the individual member of the list is identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list based on presentation in a common group without indications to the contrary.

[0047] Concentrations, dimensions, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include the numerical values explicitly recited as the limits of the range, as well as to include all the individual numerical values or sub-ranges encompassed within that range as the individual numerical value and/or sub-range is explicitly recited. For example, a weight ratio range of about 1 wt% to about 20 wt% should be interpreted to include the explicitly recited limits of 1 wt% and 20 wt% and to include individual weights such as about 2 wt%, about 11 wt%, about 14 wt%, and sub-ranges such as about 10 wt% to about 20 wt%, about 5 wt% to about 15 wt%, etc.

EXAMPLES

[0048] The following examples illustrate the technology of the present disclosure. However, it is to be understood that the following is merely illustrative of the housings, electronic devices, and methods herein. Numerous modifications and alternative methods and systems may be devised without departing from the present disclosure. Thus, while the technology has been described above with particularity, the following provides further detail in connection with what are presently deemed to be the acceptable examples.

Example 1 - Electronic Device Housing

[0049] An example electronic device housing is prepared as follows. A magnesium alloy substrate having a thickness in the range of about 0.3 mm to about 2 mm and in the shape of a housing for an electronic device is cleaned by submerging the substrate in a degreasing solution for about 30 seconds to about 180 seconds. The degreasing solution includes from about 0.3 wt% to about 2 wt% of a sodium compound and water. The sodium compound includes sodium caseinate, sodium polyacrylate, sodium polyoxyethylene alkyl ether carboxylate, sodium dodecyl sulfate, or a combination thereof. The magnesium alloy substrate is rinsed with deionized water and allowed to air dry. A passivation layer may be applied on the cleaned magnesium alloy substrate. The passivation layer includes from about 3 w% to about 15 wt% of an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof with a balance of water. Following application of the passivation layer, the substrate with the passivation layer thereon was baked at a temperature ranging from about 60 °C to about 120 °C for a time period ranging from about 10 minutes to about 30 minutes. A sealer layer is then applied over the passivation layer by submerging the substrate with the passivation layer thereon in an aqueous sealing dispersion for a time period ranging from about 60 seconds to about 120 seconds. The aqueous sealing dispersion includes from about 5 wt% to about 30 wt% sodium silicate, aluminum powder, zinc powder, or a combination thereof and can include from about 0.1 wt% to about 3 wt% graphene powder, clay powder or a combination thereof dispersed in water. Following application of the sealer layer, the housing is baked at a temperature ranging from about 60 °C to about 120 °C for a time period ranging from about 10 minutes to about 30 minutes to remove water and minimize or prevent surface corrosion of the sealing layer as it dried. The housing formed using the methodology above includes an anti-corrosive coating that can be capable of passing a 96 hour salt fog test conducted in accordance with the procedure specified in MIL-STD-81 OF.

Example 2 - Assembly of Electronic Device

[0050] An anti-corrosive metal housing for an electronic device as described above in Example 1 is placed to partially surround an electronics circuit board of a smart phone or tablet computer. The housing is placed such that a metal surface containing waterborne paint coating and the fluoropolymer layer is on an exterior surface of the substrate to which they are applied relative to the positioning of the electronic component. The electronic device has an aesthetically pleasing colored appearance and exhibits corrosion resistance.

Claims

CLAIMS What is Claimed Is:

1 . An anti-corrosive metal housing for an electronic device, comprising: a metal substrate; a passivation layer including an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or combination thereof; and a sealing layer including sodium silicate, aluminum powder, zinc powder, graphene powder, clay powder, or a combination thereof.

2. The anti-corrosive metal housing claim 1 , wherein the metal substrate further includes a paint coating, wherein the paint coating includes a primer layer, a basecoat layer, a topcoat layer, an anti-finger print layer, or a combination thereof.

3. The anti-corrosive metal housing of claim 1 , wherein the metal substrate has a density ranging from about 0.5 g/cm³ to about 9 g/cm³ and wherein the metal substrate includes aluminum, magnesium, lithium, titanium, zinc, niobium, mixtures, or alloys thereof.

4. The anti-corrosive metal housing of claim 1 , wherein a thickness of the passivation layer is from about 1 pm to about 5 pm and wherein a thickness of the sealing layer is from about 0.5 pm to about 5 pm.

5. The anti-corrosive metal housing of claim 1 , wherein the metal substrate includes an inner surface and the inner surface has an inner passivation layer and an inner sealing layer formed thereon, wherein the inner passivation layer includes an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or combination thereof, and wherein the inner sealing layer includes sodium silicate, aluminum, zinc, graphene, clay or a combination thereof.

6. An electronic device comprising: an electronic component of an electronic device; and an anti-corrosive metal housing to support the electronic components comprising: a metal substrate; a passivation layer including an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or combination thereof; and a sealing layer including sodium silicate, aluminum powder, zinc powder, graphene powder, clay powder, or a combination thereof.

7. The electronic device of claim 6, wherein the metal housing is shaped as a housing of a laptop, a desktop computer, a smartphone, a tablet, a printer, a monitor, a keyboard, a pair of headphones, a television, a speaker, a docking station, a webcam, a smart watch, a calculator, or a combination thereof.

8. The electronic device of claim 6, wherein the metal substrate has an average thickness from about 0.3 mm to about 2 mm, the passivation layer has an average thickness from about 1 pm to about 5 pm, and the sealing layer has an average thickness from about 0.5 pm to about 3 pm.

9. The electronic device of claim 6, wherein the metal housing further includes a paint coating and wherein the paint coating includes a primer layer, a basecoat layer, a topcoat layer, an anti-fingerprint layer, or a combination thereof.

10. A method of applying an anti-corrosion treatment to a metal substrate of a housing for an electronic device, comprising: treating a metal substrate in an aqueous oxyanion passivation bath to form a passivated metal substrate, wherein the oxyanion passivation bath includes from about 3 wt% to about 15 wt% molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or combination thereof; and treating the passivated metal substrate with an aqueous sealing dispersion to form the metal substrate with the anti-corrosion treatment thereon, wherein the sealing dispersion includes from about 5 wt% to about 30 wt% sodium silicate, aluminum powder, zinc powder, or a combination thereof and from about 0.1 wt% to about 3 wt% graphene powder, clay powder, or a combination thereof.

11 . The method of claim 10, wherein the sealing dispersion includes the sodium silicate at from about 20 wt% to about 25 wt%, and the aluminum powder, the zinc powder, or a combination thereof at from about 2 wt% to about 5 wt%.

12. The method of claim 10, wherein the graphene powder, the clay powder, or the combination thereof has an average particle size ranging from about 0.1 pm to about 10 pm.

13. The method of claim 10, further comprising degreasing the metal substrate in a degreasing solution prior to the treating of the metal substrate in the oxyanion passivation bath, wherein the degreasing solution includes from about 0.3 wt% to about 2 wt% sodium caseinate, sodium polyacrylate, sodium polyoxyethylene alkyl ether carboxylate, sodium dodecyl sulfate, or combination thereof.

14. The method of claim 10, further comprising: spray coating the metal substrate following treatment with the aqueous sealing dispersion with a primer formulation, a basecoat formulation, a topcoat formulation, an anti-fingerprint formulation, or a combination thereof, and

UV curing the primer formulation, the basecoat formulation, the topcoat formulation, the anti-fingerprint formulation, or the combination thereof with a UV light source at from about 700 mJ/cm² to about 1 ,200 mJ/cm² to polymerize polymers in the basecoat formulation, the topcoat formulation, the anti-fingerprint formulation, or the combination thereof.

15. The method of claim 14, wherein the method includes the spray coating with the topcoat formulation, and wherein the topcoat formulation includes a first topcoat and a second topcoat, wherein, the first topcoat includes from about 30 wt% to 65 about wt% polyester, acrylic, polyurethane, copolymers, or admixtures thereof, and wherein the second topcoat includes from about 50 wt% to about 80 wt% polyacrylic, polyurethane, urethane acrylates, acrylic acrylates, epoxy acrylates, copolymers, or admixtures thereof.