WO2020105013A1

WO2020105013A1 - Structural panels for electronic devices

Info

Publication number: WO2020105013A1
Application number: PCT/IB2019/060088
Authority: WO
Inventors: Jong-Min Choi; Somasekhar BOBBA; Remesh KUZHIKKALI; Jong Woo Lee; Bongjun Park; Rajkumar KARTHIKEYAN
Original assignee: Sabic Global Technologies B.V.
Priority date: 2018-11-22
Filing date: 2019-11-22
Publication date: 2020-05-28

Abstract

A structural panel for an electronic device having an electromagnetic energy at a wavelength comprises first and second metal layers each independently having a plurality of apertures; and a core layer disposed between and in direct physical contact with the first and second metal layers, the core layer comprising a polymeric material which at least partially fills the apertures of the first and second metal layers to mechanically connect the first and second metal layers to the core layer, wherein the apertures have a pitch of less than 0.25 λ, and λ is the wavelength of the electromagnetic energy, and optionally λ is 2 centimeters to 200 centimeters.

Description

STRUCTURAL PANELS FOR ELECTRONIC DEVICES

BACKGROUND

[0001] The disclosure relates to structural panels, and in particular structural panels for electronic devices and their methods of manufacture.

[0002] Electronic devices such as electronic displays often have a structural panel that provides damage resistance, structural integrity and environmental protection to these devices. The structural panel can also dissipate heat generated by various components of the electronic devices.

[0003] The current electronic displays can have a size of over 100 inches. With the advance of technology, the size of the electronic displays is expected to increase further. Certain electronic displays use glass based laminates as the structural panel. While the glass panel provides adequate structural support and protection to the displays, the panel itself can be very heavy, which raises concerns in the assembly line and product transportation. Accordingly, there is a need in the art for a structural panel having reduced weight as compared to the existing glass based structural panels.

It would be a further advantage if the lightweight structural panel has comparable mechanical and heat dissipation properties as the conventional glass panels.

SUMMARY

[0004] A structural panel for an electronic device having an electromagnetic energy at a wavelength is disclosed. The structural panel comprises: first and second metal layers each independently having a plurality of apertures; and a core layer disposed between and in direct physical contact with the first and second metal layers, the core layer comprising a polymeric material which at least partially fills the apertures of the first and second metal layers to

mechanically connect the first and second metal layers to the core layer, the polymeric material comprising at least one of a low density polyethylene and a polycarbonate, wherein the apertures have a pitch of less than 0.25 l, and l is the wavelength of the electromagnetic energy, and optionally l is 2 centimeters to 200 centimeters.

[0005] A method of forming a structural panel for an electronic device comprises: disposing a core layer between first and second metal layers to form an assembly, the core layer comprising a polymeric material having a glass transition temperature, the polymeric material comprising at least one of a low density polyethylene and a polycarbonate, and the first and second metal layers each independently having a plurality of apertures; and pressing and heating the assembly to a temperature that is above the glass transition temperature of the polymeric material such that the polymeric material at least partially fills the apertures of the first and second metal layers to mechanically lock the first and second metal layers to the core layer to form the structural panel.

[0006] A display device comprising the structural panel is also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A description of the figures, which are meant to be exemplary and not limiting, is provided in which:

[0008] FIG. 1 is a top view of a portion of an example of a structural panel having a core layer sandwiched between two metal layers that have symmetrical apertures;

[0009] FIG. 2 is a cross-sectional view of a portion of the structural panel shown in FIG. 1;

[0010] FIG. 3 is a top view of a portion of an example of a structural panel having a core layer sandwiched between two metal layers that have unsymmetrical apertures with the same shape;

[0011] FIG. 4 is a cross-sectional view of a portion of the structural panel shown in FIG. 3 along the dashed line;

[0012] FIG. 5 is a side view of an example of an aperture on a metal layer of a structural panel;

[0013] FIG. 6 is a cross-sectional view of a portion of the structural panel having a core layer sandwiched between two metal layers that have symmetrical apertures as illustrated in FIG. 5;

[0014] FIG. 7 is a top view of a portion of an example of a structural panel having a core layer sandwiched between two metal layers that have unsymmetrical apertures;

[0015] FIG. 8 is a cross-sectional view of a portion of the structural panel shown in FIG. 7 along the dashed line;

[0016] FIG. 9 is a flow chart showing an example of a process of making structural panels having a core layer sandwiched between two metal layers that have apertures;

[0017] FIG. 10 shows the setup of an example of a pressure load finite element (FE) model;

[0018] FIG. 11 compares the displacement of a control panel and panels of examples 1-4 under difference forces;

[0019] FIG. 12 shows the setup of a temperature load FE model;

[0020] FIG. 13 is a top view of the structural panel of Example 6;

[0021] FIG. 14 is top view of a section of the structural panel shown in FIG. 13;

[0022] FIG. 15 is a side view of the structural panel shown in FIG. 13;

[0023] FIG. 16 is a cross-sectional view of a section of the structural panel shown in FIG.

15; [0024] FIG. 17 is a side view of a portion of a display device according to an embodiment of the disclosure;

[0025] FIG. 18 is a top view of the display device shown in FIG. 17; and

[0026] FIG. 19 is a cross-sectional view of a portion of the display device shown in FIG. 18 along the A-A direction.

DETAILED DESCRIPTION

[0027] Lightweight structural panels having good structural integrity and heat dissipation properties are provided. The structural panels have perforated metal layers and a polymeric core layer disposed between and in direct physical contact with the metal layers. Advantageously, no adhesives are needed, and the polymeric material of the core layer can at least partially fill the perforated holes in the metal layers through a hot pressing process to mechanically lock the metal layers to the polymeric core layer. In addition, the perforation on the metal layers can be carefully selected so that the lightweight structural panels can have enhanced electromagnetic shielding capacity and improved visible light transparency. These lightweight structural panels can also have one or more of high modulus, enhanced durability, good electrostatic discharge performance, or more efficient CTE (coefficient of thermal extension) control by eliminating adhesives between layers.

[0028] The metal layers comprise at least one of aluminum, an aluminum alloy, a carbide alloy, copper, a copper alloy, iron, an iron alloy such as steel, a titanium alloy, magnesium, a magnesium alloy, beryllium, a beryllium alloy, lead, a lead alloy, zinc, and a zinc alloy. Examples of copper alloys include bronze, brass, Kelmet alloy (i.e., a Cu-Pb system or a Cu-Sn-Pb system). As used herein, a carbide alloy means an alloy that contains a carbide. Examples of carbide alloys include tungsten and vanadium carbide alloys, tungsten carbide cobalt alloys, tungsten carbide copper alloys, titanium carbide tungsten alloys, and the like. Preferably, the metal layers comprise an aluminum alloy. The metal layers can have a thickness of 0.1 millimeter to 10 millimeters, 0.1 millimeter to 5 millimeters, 0.1 millimeter to 1 millimeter, 0.5 millimeter to 1 millimeter, or 1 millimeter to 10 millimeters. Different metal layers can have the same thickness. Alternatively, different metal layers in the same structural panel can have a different thickness.

[0029] The apertures on the metal layers can be symmetric or asymmetric. The shapes of the apertures include circles, polygons, coness, and the like. As used herein, conical apertures refer to apertures that taper smoothly from a surface of a metal layer to the opposing surface of the same metal layer. Preferably the conical apertures taper smoothly from an outer surface of a metal layer that is opposite to the core layer to an opposing inner surface of the same metal layer that is in direct physical contact with the core layer.

[0030] The apertures can be uniformly spaced or can be non-uniformly spaced. In an embodiment, the apertures distribute uniformly over the entire surface of a metal layer. The density of the apertures on the metal layers can vary. At least one of the metal layers can have 2 to 4 apertures per square centimeter or per square decimeter surface area of the metal layers.

[0031] The distance or pitch between the apertures on a metal layer can be less than 0.25 l, where l is the wavelength of an electromagnetic energy that the electronic device may generate. Such structural panels can provide shielding effects to the electromagnetic energy having a wavelength of l. For TVs, the electromagnetic energy to be shielded can have a frequency of 640 megahertz (MHz) and a wavelength of 46.843 centimeters (cm). When the distance or pitch between the apertures is less than 117 millimeters (0.25 l), the structural panels as disclosed herein can provide have an electromagnetic shielding efficiency of 32 decibel (dB) or greater at 640 MHz as determined by ASTM D4935. Such structural panels are particularly useful as TV back panels. The distance or pitch between the apertures on a metal layer can be 0.5 millimeter to 50

millimeters, 0.5 millimeter to 5 millimeters, 5 millimeters to 50 millimeters, 10 millimeters to 40 millimeters, or 15 millimeters to 35 millimeters. As used herein, the distance (“d”) is measured from the center of an aperture to the center of an adjacent aperture as shown in FIG. 1.

[0032] The open areas of the apertures can be tuned to achieve the desired transparency as well as desired bonding strength between the metal layers and the core layer. As used herein, an open area of the apertures refers to a size of individual apertures at each surface of the metal layers.

[0033] The open areas of an aperture on the opposing surfaces of a particular metal layer can be the same or different. In the structural panel, the surface of the metal layer that contacts the core layer is referred to as the inner surface, and the surface of the metal layer that is opposite to the core layer is referred to as the outer layer. In an embodiment, at least a portion of the apertures have a greater open area on the outer surface of a metal layer than on the inner surface of the same metal layer. For example, the sum of the open areas on the outer surface of a particular metal layer relative to the sum of the open areas on the inner surface of the same particular metal layer can be greater than 1:1 to 5:1, 1.5:1 to 4:1, or 2:1 to 4:1. An illustrative example of such apertures is shown in FIGS. 2 and 4.

[0034] For the structural panels, at the inner surface of a metal layer, each aperture can have an open area of 7 square millimeters (mm²) to 113 square millimeters, 7 square millimeters to 28 square millimeters or 28 square millimeters to 113 square millimeters. At the outer surface of a metal layer, each aperture can have an open area of 28 square millimeters to 200 square millimeters, 28 square millimeters to 78 square millimeters or 78 square millimeters to 200 square millimeters. The sum of the open areas on a given surface of a metal layer can be 30% to 70%, based on the total area of the given surface.

[0035] The apertures on one metal layer can be symmetrical to the apertures on the other metal layer. In other words, for each aperture on a first metal layer disposed on one side of the core layer, there is a corresponding aperture with the same size and shape on the second meal layer located on the other side of the core layer. Alternatively, the apertures on one of the metal layers can be asymmetrical to the apertures on the other metal layer. In an embodiment, greater than or equal to 75%, preferably greater than or equal to 90%, of the apertures on a first metal layer are asymmetrical to the apertures on a second metal layer.

[0036] The metal layers can be directly disposed on a surface of the core layer, i.e., in physical contact with the surface of the core layer. The core layer can be a single polymeric layer or include multiple polymeric layers where each layer can be the same or different in terms of the material and the thickness.

[0037] The core layer can comprise a polymeric material such as a thermoplastic polymer, a thermoset polymer, or a combination comprising at least one of the foregoing. In the structural panels, the polymeric material fills at least a portion of the apertures in the metal layers. For example, the polymeric material fills greater than 80 vol%, greater than 90 vol%, or great than 99 vol% of the voids created by the apertures in the metal layers. Such filling effectively integrates or locks the metal layers with the polymeric core layer without using any additives between the layers. In other words, the layers of the structural panel can consist of a core layer located between two metal layers. The structural panel can be free of a binder layer, an adhesive layer, or the like.

[0038] Polymeric materials are chosen based upon requirements for the core layer such as transparency level, modulus, glass transition temperature, density, flame retardant properties, coefficient of thermal extension, and thermal conductivity. Possible polymeric materials include, but are not limited to, oligomers, polymers, ionomers, dendrimers, and copolymers such as graft copolymers, block copolymers (e.g., star block copolymers, random copolymers, and the like) or a combination comprising at least one of the foregoing. Examples of such polymeric materials include, but are not limited to, polyesters (e.g., polybutylene terephthalate (PBT), polyester elastomers), polycarbonates, polystyrenes (e.g., copolymers of polycarbonate and styrene, polyphenylene ether-polystyrene blends), polyimides (e.g., polyetherimides (PEI)), acrylonitrile- styrene-butadiene (ABS), polyarylates, polyalkylmethacrylates (e.g., polymethylmethacrylates (PMMA)), polyolefins (e.g., polypropylenes (PP) and polyethylenes, (such as high density polyethylenes (HDPE), low density polyethylenes (LDPE), linear low density polyethylenes (LLDPE))), polyamides (e.g., polyamideimides), polyarylates, polysulfones (e.g., polyarylsulfones such as polyphenylsufones (PPS), polysulfonamides), polyphenylene sulfides,

polytetrafluoroethylenes, polyethers (e.g., polyether ketones (PEK), polyether etherketones (PEEK), polyethersulfones (PES)), polyacrylics, polyacetals (also known as polyoxymethylene (POM)), polybenzoxazoles (e.g., polybenzothiazinophenothiazines, polybenzothiazoles), poly(p- phenylene oxide) (PPO), polyoxadiazoles, polypyrazinoquinoxalines, polypyromellitimides, polyquinoxalines, polybenzimidazoles, polyoxindoles, polyoxoisoindolines (e.g.,

polydioxoisoindolines), polytriazines, polypyridazines, polypiperazines, polypyridines,

polypiperidines, polytriazoles, polypyrazoles, polypyrrolidones, polycarboranes,

polyoxabicyclononanes, polydibenzofurans, polyphthalamide (PPA), polyacetals, polyanhydrides, polyvinyls (e.g., polyvinyl ethers, polyvinyl thioethers, polyvinyl alcohols, polyvinyl ketones, polyvinyl halides, polyvinyl nitriles, polyvinyl esters, polyvinylchlorides), polysulfonates, polysulfides, polyureas (e.g. thermoplastic polyurethanes (TPU)), polyphosphazenes, polysilazanes, polysiloxanes, fluoropolymers (e.g., polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), fluorinated ethylene-propylene (FEP), polyethylene tetrafluoroethylene (ETFE)), liquid crystal polymers (LCP), or a combination comprising at least one of the foregoing. Polyethylenes such as low density polyethylenes and polycarbonates including polycarbonate homopolymers, copolycarbonates and polycarbonate copolymers are especially preferred. In an embodiment, the polymeric material comprises a polycarbonate copolymer or polycarbonate blend.

[0039] The core layer can include fillers or reinforcing agents including, for example, glass, carbon, metal, mineral, and polymers such as polytetrafluoroethylene (PTFE), silicone, aromatic polyimide (aramid), and the like. The fillers or reinforcing agents can be present in a particulate form or a fiber form. Fillers or reinforcing agents can be used in amounts of 1 to 50 parts by weight or 1 to 40, or 1 to 30 pats by weight, based on the 100 parts by weight of the polymeric materials in the core layer.

[0040] The core layer can include various additives ordinarily incorporated into the selected polymeric materials, with the proviso that the additive(s) are selected to not adversely affect the desired properties of the core layer, in particular, transparency and flexural stiffness. Such additives can be mixed at a suitable time during the mixing of the components for forming the core layer. Exemplary additives include impact modifiers, fillers, reinforcing agents, antioxidants, heat stabilizers, light stabilizers, ultraviolet (UV) light stabilizers, plasticizers, lubricants, mold release agents, antistatic agents, colorants (such as carbon black and organic dyes), surface effect additives, radiation stabilizers (e.g., infrared absorbing), flame retardants, and anti-drip agents. A

combination of additives can be used, for example, a combination of a heat stabilizer, mold release agent, and ultraviolet light stabilizer. The total amount of additives (other than any impact modifier, filler, or reinforcing agents) can be 0.001 weight percent (wt%) to 5 wt%, based on the total weight of the composition of the core layer.

[0041] The thickness of the core layer can vary depending upon the application. In an embodiment, the core layer between the metal layers but not in the apertures has a thickness that is 25% to 55% of the overall thickness of the structural panel, or 25% to 40%, or 40% to 55% of the overall thickness of the structural panel. The overall thickness of the structure panel can be 1 millimeter to 10 millimeters or 1 millimeter to 5 millimeters. Illustratively, the core layer can have a thickness of 0.8 millimeter to 1.6 millimeters, 0.8 millimeter to 1.2 millimeters, or 1.2 millimeters to 1.6 millimeters for a structural panel having an overall thickness of 3 millimeters.

[0042] The structural panels can have a total transmission of 30% to 40% of light having a wavelength in the range of 360 nanometers to 750 nanometers determined according to ASTM D- 1003-00, Procedure A, under D65 illumination, with a 10 degrees observer, at a thickness of 3 millimeters using a Haze-Gard test device.

[0043] In a preferred aspect, a structural panel for an electronic device having an

electromagnetic energy at a wavelength includes: first and second metal layers including at least one of aluminum, an aluminum ahoy, a carbide ahoy, copper, a copper ahoy, iron, an iron ahoy, a titanium ahoy, magnesium, a magnesium ahoy, beryllium, a beryllium ahoy, lead, a lead ahoy, zinc, or a zinc ahoy, still more preferably wherein each of the first and second layers including aluminum or an aluminum ahoy. In addition, a core layer is disposed between and in direct physical contact with the first and second metal layers, the core layer including least one of a low density

polyethylene and a polycarbonate, preferably a polycarbonate copolymer or polycarbonate blend, which at least partially fills the apertures of the first and second metal layers to mechanically connect the first and second metal layers to the core layer, preferably in the absence of an adhesive. Preferably the core layer between the first and second metal layers but not in the apertures has a thickness that is 25% to 55% of an overall thickness of the structural panel. In this aspect the apertures have a pitch of 0.5 millimeter to 50 millimeters, preferably 10 millimeters to 40 millimeters, more preferably 15 millimeters to 35 millimeters, and l is the wavelength of the electromagnetic energy, and optionally wherein l is 2 centimeters to 200 centimeters. Further in this aspect the apertures on the first metal layer have an open area of 7 to 113 square millimeters and 28 to 200 square millimeters respectively on the inner and outer surfaces of the first metal layer. The pane of this aspect can have a total transmission of 30% to 40% of light having a wavelength in the range of 360 nanometers to 750 nanometers determined according to ASTM D- 1003-00, Procedure A, under D65 illumination, with a 10 degrees observer, at a thickness of 3 millimeter using a Haze-Gard test device.

[0044] Examples of structural panels are illustrated in FIGS 1-4 and 6-8. Structural panels (10, 20, 30, 40) have a core layer (13, 23, 33, 43), and a first metal layer (12, 22, 32, 42) and a second metal layer (14, 24, 34, 44) disposed on the opposing sides of the core layer. The apertures on the first metal layer (11, 21, 31, 41) can be symmetrical to the apertures on the second metal layer (15, 25, 35, 45) as shown in FIGS. 2 and 6. Alternatively, the apertures on the first and second metal layers can be asymmetrical as shown in FIGS. 4 and 8. Asymmetrical apertures can be wholly unaligned. Optionally asymmetrical apertures can partially align.

[0045] As a specific example, the structural panels have first and second metal layers (such as aluminum alloy layers) and a core layer comprising at least one of a low density polyethylene and a polycarbonate disposed between and in direct physical contact with the first and second metal layers. Each metal layer has an inner surface contacting the core layer and an outer surface opposing the core layer. The first and second metal layers can have conical apertures, wherein the smallest diameter of the conical apertures is preferably adjacent the inner surface. The distance between the apertures can be 20 centimeters to 30 centimeters. The open area of the apertures on the inner surface of the metal layers can be 65 to 85 square millimeters, and the open area of the apertures on the outer surface of the metal layers can be 10 to 28 square millimeters. The metal layers can, individually, have a thickness of 0.1 millimeter to 1 millimeter and the core layer can have a thickness of 1 millimeter to 2 millimeters.

[0046] The structural panels can be manufactured by disposing a core layer between first and second metal layers to form a stack, and pressing and heating the stack to a temperature that is equal to or above the glass transition temperature of the polymeric material in the core layer such that the polymeric material at least partially fills the apertures of the first and second metal layers to mechanically lock the first and second metal layers to the core layer.

[0047] The core layer can be formed by an extrusion, calendaring, molding (e.g., injection molding), thermoforming, vacuum forming, or other desirable forming process. The metal layers can be extruded and then perforated. In an embodiment, the metal layers are perforated using a stamping process. Initially, a piercing operation is carried out using piercing punches arranged in a symmetrical or asymmetrical pattern. To make conical apertures, chamber or conical edges can be subsequently formed using piloting punches arranged in a symmetrical or asymmetrical pattern.

[0048] In an embodiment, the stack of the metal-core-metal layers is heated to a temperature that is 20 to 50°C above the glass transition temperature of the polymeric material in the core layer. Simultaneously or after the core and the metal layers are heated to the desired temperature, the stack is compressed at a pressure of 100 tonnes per square meter to 200 tonnes per square meter or 200 tonnes per square meter to 500 tonnes per square meter. The pressing can be a single stage or multi stage pressing.

[0049] An exemplary process is shown in FIG. 9. In the process, a core layer is formed from a polymeric material by extrusion, and metal layers are perforated. The core layer and the metal layers are stacked up and placed on a press platen. Then the stack is heated up to a temperature that is at least above the glass transition temperature of the polymeric core and pressed (e.g., under a predetermined pressure or following a predetermined pressure profile). The formed panel is cooled down and machined to have aesthetic side surfaces if needed.

[0050] The structural panels can be used in various display devices such as organic light emitting diode (OLED) displays, quantum dot light emitting diode (QLED) displays, liquid crystal displays (LCD), micro light emitting diode (micro LED) displays, and the like. In an embodiment, the display device has a display panel, which is coupled to the structural panel as disclosed herein. Preferably, the display panel contains a polymeric material, which encapsulates or is overmolded to the structural panel, for example along the periphery of the structural panel. The edges of the display device can be decorated, for example, with markings such as alphanumeric s, graphics, symbols, indicia, logos, aesthetic designs, multicolored regions, and a combination comprising at least one of the foregoing. The structural panel can be thinner at the edges to facilitate its coupling to the display panel. Alternatively or in addition, a double-sided adhesive tape can be used to couple the structural panel to the displayer panel. Known mechanical means can also be used to integrate the structural panel to the display panel. The display devices as disclosed herein are durable and can have minimized edge debonding.

[0051] An example of the display device is shown in FIGS. 17-19. The display device (60) includes a display panel (66) and a structural panel having a core layer (63), metal layers (62, 64) with apertures (61, 65), where the display panel is coupled to the structural panel along the periphery of the structural panel via encapsulation or overmolding with a polymeric material of the display panel. The thickness of the structural panel at the periphery (hi) can be less than the thickness of the structural panel (h2) that are not encapsulated or overmolded with a polymeric material of the display panel.

[0052] In a preferred aspect, the structural panel is a television (TV) back cover, preferably wherein the TV back cover shield electromagnetic energy has a frequency of 640 MHz and a wavelength of 46.843 cm, more preferably wherein the TV back cover has an electromagnetic shielding efficiency of 32 dB or greater at 640 megahertz as determined by ASTM D4935. [0053] The structural panels according to the disclosure are further illustrated by the following non-limiting examples.

EXAMPLES

Examples 1-4

[0054] Various structural panels were constructed. Each of the panels has a core layer and two metal layers disposed on the opposing surfaces of the core layer. The control panel (control 1) does not have any apertures on the metal layers. Panels of Ex 1 to Ex 4 have apertures on the metal layers, and these panels are illustrated in FIGS. 2, 4, 6, and 8 respectively. The information for the panels is summarized in Table 1.

Table 1.

¹ mm: millimeter

² Avg. D: average distance between the apertures

³ Area 1 : open area of the apertures on the side of the top metal layer/bottom metal layer that contacts the core layer

⁴ Area 2: open area of the apertures on the side of the top metal layer/bottom metal layer that that is opposite the core layer

⁵ PC: polycarbonate

[0055] The displacement of the panels was studied using a pressure load finite element (FE) model. The pressure FE model setup is shown in FIG. 10, wherein A means that points of support are selected in X, Y, Z translation and rotational directions (boundary conditions), and P means pressure load. The force was 33.34 Newton, the tested area was 1,146,000 square millimeters, and the pressure was 0.0000291 Newton/square millimeters. The displacement measured at the center of the panels is shown in Table 2 and FIG. 11.

Table 2.

*Kg means kilograms; N refers to Newton, and mm means millimeter

[0056] The displacement (thermal deformations) of the panels was also studied using a temperature load FE model. The temperature model setup is shown in FIG. 12, wherein A means that points of support are selected in X, Y, Z translation and rotational directions (boundary conditions). Room temperature was 23°C. A temperature of 60°C was applied on all nodes of the outer surface of the metal and core layers. The results are summarized in Table 3.

Table 3.

*Kg means kilograms; N refers to Newton, and mm means millimeter

[0057] The results indicate that the panels according to the disclosure have reduced stiffness as compared to the control panel. Nonetheless, the panels of the disclosure can still meet the requirement for TV back covers. In addition, with the elimination of adhesives between the core and the metal layers, it is expected that the lightweight structural panels according to the disclosure can have good electrostatic discharge performance or more efficient CTE (coefficient of thermal extension) control. Father, panels according to the disclosure have a visible light transparency of 30% to 40% thus allowing a user to see through the panel if desired. It is also expected that the panels of the disclosure have improved electromagnetic shielding capacity as compared to the control panel.

Example 5

[0058] The example compares the thermal performance of a perforated panel according to the disclosure (Ex 5) and a control panel without perforation (Control 2). Each panel has a polycarbonate core layer (1.6 mm) sandwiched between two aluminum layers, where each of the aluminum layers has a thickness of 0.7 mm. Both structural panels were 1450 mm x 790 mm.

[0059] The control panel (Control 2) does not have apertures on the aluminum layers, and the aluminum layers are laminated to the core layer via adhesives. For the structural panel according to the disclosure (Ex 5), as shown in FIGS. 13-16, the aluminum layers (52, 54) have apertures (51, 55) with a diameter of 6 mm and the average distance between the apertures of 25 mm. The polycarbonate core layer (53) fills the apertures (51, 55) locking the aluminum layers (52, 54) to the core layer (53) without using an adhesive.

[0060] A temperature of 60°C was applied to one surface of the panel (“top surface”) and the temperature of the opposing surface (“bottom surface”) was measured at steady state. The results are shown in Table 4.

Table 4.

[0061] The results show that the panels according to the disclosure have similar heat dissipation performance as compared to the control panel. As described herein, with the elimination of adhesives between the aluminum layers and the core layer, together with the formation of apertures on the aluminum layers, the panels of the disclosure are expected to have enhanced magnetic shielding effects, enhanced visible light transmission, reduced weight especially when used in electronic displays having a size of over 100 inches, and more efficient CTE

(coefficient of thermal extension) control.

[0062] Set forth are various aspects of the disclosure.

[0063] Aspect 1. A structural panel for an electronic device having an electromagnetic energy at a wavelength, the structural panel comprising: first and second metal layers each independently having a plurality of apertures; and a core layer disposed between and in direct physical contact with the first and second metal layers, the core layer comprising a polymeric material comprising at least one of a low density polyethylene and a polycarbonate, preferably a polycarbonate copolymer or polycarbonate blend, and which at least partially fills the apertures of the first and second metal layers to mechanically connect the first and second metal layers to the core layer, wherein the apertures have a pitch of less than 0.25 l, the pitch being the distance between apertures, measured from the center of an aperture to the center of an adjacent aperture, and l is the wavelength of the electromagnetic energy, and optionally wherein l is 2 centimeters to 200 centimeters.

[0064] Aspect 2. The structural panel of Aspect 1, wherein the apertures have a pitch of 0.5 millimeter to 50 millimeters, preferably 10 millimeters to 40 millimeters, more preferably 15 millimeters to 35 millimeters. [0065] Aspect 3. The structural panel of Aspect 1 or Aspect 2, wherein the first and second metal layers each independently comprises at least one of aluminum, an aluminum alloy, a carbide alloy, copper, a copper alloy, iron, an iron alloy such as steel, a titanium alloy, magnesium, a magnesium alloy, beryllium, a beryllium alloy, lead, a lead alloy, zinc, and a zinc alloy, preferably the polymeric material comprises a polycarbonate copolymer or polycarbonate blend; and the first and second metal layers each independently comprises an aluminum alloy.

[0066] Aspect 4. The structural panel of any one of Aspects 1 to 3, wherein the structural panel is free of an adhesive.

[0067] Aspect 5. The structural panel of any one of Aspects 1 to 4, wherein each of the first and second metal layers has an inner surface contacting the core layer and an outer surface opposing the core layer; and at least a portion of the apertures on the first metal layer have a greater open area on the outer surface of the first metal layer than on the inner surface of the first metal layer.

[0068] Aspect 6. The structural panel of Aspect 5, wherein at least a portion of the apertures on the second metal layer have a greater open area on the outer surface of the second metal layer than on the inner surface of the second metal layer.

[0069] Aspect 7. The structural panel of Aspect 5 or Aspect 6, wherein the apertures on the first metal layer have an open area of 7 to 113 square millimeters and 28 to 200 square millimeters respectively on the inner and outer surfaces of the first metal layer.

[0070] Aspect 8. The structural panel of any one of Aspects 1 to 7, wherein the apertures on the first metal layer are symmetrical to the apertures on the second metal layer.

[0071] Aspect 9. The structural panel of any one of Aspects 1 to 7, wherein the apertures on the first metal layer are asymmetrical to the apertures on the second metal layer.

[0072] Aspect 10. The structural panel of any one of Aspects 1 to 9, wherein the core layer between the first and second metal layers but not in the apertures has a thickness that is 25% to 55% of an overall thickness of the structural panel.

[0073] Aspect 11. The structural panel of any one of Aspects 1 to 10, wherein the first and second metal layers each independently has a thickness of 0.1 millimeter to 1 millimeter, and the structural panel has an overall thickness of 1 millimeter to 10 millimeters.

[0074] Aspect 12. The structural panel of any one of Aspects 1 to 11, wherein the panel has a total transmission of 30% to 40% of light having a wavelength in the range of 360 nanometers to 750 nanometers determined according to ASTM D- 1003-00, Procedure A, under D65 illumination, with a 10 degrees observer, at a thickness of 3 millimeter using a Haze-Gard test device.

[0075] Aspect 13. The structural panel of any one of Aspects 1 to 12, wherein the structural panel is a TV back cover, preferably wherein the TV back cover shield electromagnetic energy having a frequency of 640 MHz and a wavelength of 46.843 cm, more preferably the TV back cover has an electromagnetic shielding efficiency of 32 dB or greater at 640 megahertz as determined by ASTM D4935.

[0076] Aspect 14. A display device comprising the structural panel of any one of Aspects 1 to 13.

[0077] Aspect 15. The display device of Aspect 14 further comprising a display panel and the display panel is coupled to the structural panel via a polymeric material overmolded to the structural panel.

[0078] Aspect 16. The electronic device of Aspect 14 or Aspect 15, wherein the display device is an organic light emitting diodes display device, a quantum dot light emitting diode display, a liquid crystal display, or a micro light emitting diode display.

[0079] Aspect 17. A method of forming a structural panel for an electronic device, the method comprising: disposing a core layer between first and second metal layers to form an assembly, the core layer comprising a polymeric material having a glass transition temperature, and the first and second metal layers each independently having a plurality of apertures; and pressing and heating the assembly to a temperature that is above the glass transition temperature of the polymeric material such that the polymeric material at least partially fills the apertures of the first and second metal layers to mechanically lock the first and second metal layers to the core layer to form the structural panel.

[0080] Aspect 18. The method of Aspect 17, further comprising forming the apertures on the first and second metal layers.

[0081] Aspect 19. The method of Aspect 17 or 18, wherein the assembly is heated to a temperature that is 20 to 50 °C above the glass transition temperature of the polymeric material.

[0082] Aspect 20. The method of any one of Aspects 17 to 19, wherein the assembly is pressed at a pressure of 100 tonnes per square meter to 500 tonnes per square meter.

[0083] The singular forms“a,”“an,” and“the” include plural referents unless the context clearly dictates otherwise. “Or” means“and/or” unless clearly indicated otherwise by context.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A“combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.“One or more of the foregoing” means at least one the listed material.

[0084] Unless otherwise specified herein, any reference to standards, regulations, testing methods and the like refers to the standard, regulation, guidance or method that is in force at the time of filing of the present application. [0085] As used herein, glass transition temperature is determined by differential scanning calorimetry (DSC) as per ASTM D3418 with a 20°C/min heating rate.

[0086] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0087] While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.

Claims

CLAIMS We claim:

1. A structural panel for an electronic device having an electromagnetic energy at a wavelength, the structural panel comprising:

first and second metal layers each independently having a plurality of apertures; and a core layer disposed between and in direct physical contact with the first and second metal layers,

the core layer comprising a polymeric material which at least partially fills the apertures of the first and second metal layers to mechanically connect the first and second metal layers to the core layer, the polymeric material comprising at least one of a low density polyethylene and a polycarbonate,

wherein the apertures have a pitch of less than 0.25 l, wherein the pitch is the distance between apertures, measured from the center of an aperture to the center of an adjacent aperture, and l is the wavelength of the electromagnetic energy, and optionally l is 2 centimeters to 200 centimeters.

2. The structural panel of claim 1, wherein the apertures have a pitch of 0.5 millimeter to 50 millimeters, preferably 10 millimeters to 40 millimeters, more preferably 15 millimeters to 35 millimeters.

3. The structural panel of claim 1 or claim 2, wherein

the first and second metal layers each independently comprises at least one of aluminum, an aluminum alloy, a carbide alloy, copper, a copper alloy, iron, an iron alloy, a titanium alloy, magnesium, a magnesium alloy, beryllium, a beryllium alloy, lead, a lead alloy, zinc, and a zinc alloy, preferably

the polymeric material comprises a polycarbonate copolymer or polycarbonate blend; and the first and second metal layers each independently comprises an aluminum alloy.

4. The structural panel of any one of claims 1 to 3, wherein the structural panel is free of an adhesive.

5. The structural panel of any one of claims 1 to 4, wherein each of the first and second metal layers has an inner surface contacting the core layer and an outer surface opposing the core layer; and at least a portion of the apertures on the first metal layer have a greater open area on the outer surface of the first metal layer than on the inner surface of the first metal layer.

6. The structural panel of claim 5, wherein at least a portion of the apertures on the second metal layer have a greater open area on the outer surface of the second metal layer than on the inner surface of the second metal layer.

7. The structural panel of claim 5 or claim 6, wherein the apertures on the first metal layer have an open area of 7 to 113 square millimeters and 28 to 200 square millimeters respectively on the inner and outer surfaces of the first metal layer.

8. The structural panel of any one of claims 1 to 7, wherein the apertures on the first metal layer are symmetrical to the apertures on the second metal layer.

9. The structural panel of any one of claims 1 to 7, wherein the apertures on the first metal layer are asymmetrical to the apertures on the second metal layer.

10. The structural panel of any one of claims 1 to 9, wherein the core layer between the first and second metal layers but not in the apertures has a thickness that is 25% to 55% of an overall thickness of the structural panel.

11. The structural panel of any one of claims 1 to 10, wherein the first and second metal layers each independently has a thickness of 0.1 millimeter to 1 millimeter, and the structural panel has an overall thickness of 1 millimeter to 10 millimeters.

12. The structural panel of any one of claims 1 to 11, wherein the panel has a total transmission of 30% to 40% of light having a wavelength in the range of 360 nanometers to 750 nanometers determined according to ASTM D- 1003-00, Procedure A, under D65 illumination, with a 10 degrees observer, at a thickness of 3 millimeter using a Haze-Gard test device.

13. A display device comprising the structural panel of any one of claims 1 to 12.

14. The display device of claim 13 further comprising a display panel and the display panel is coupled to the structural panel via a polymeric material overmolded to the structural panel, and wherein optionally the display device is an organic light emitting diodes display device, a quantum dot light emitting diode display, a liquid crystal display, or a micro light emitting diode display.

15. A method of forming a structural panel for an electronic device, the method comprising:

disposing a core layer between first and second metal layers to form an assembly, the core layer comprising a polymeric material having a glass transition temperature and comprising at least one of at least one of a low density polyethylene and a polycarbonate, wherein the first and second metal layers each independently have a plurality of apertures; and

pressing and heating the assembly to a temperature that is above the glass transition temperature of the polymeric material such that the polymeric material at least partially fills the apertures of the first and second metal layers to mechanically lock the first and second metal layers to the core layer to form the structural panel,

wherein optionally the assembly is heated to a temperature that is 20 to 50 °C above the glass transition temperature of the polymeric material.