An electronic device having improved electromagnetic interference, EMI, shielding, as well as an associated light emitting diode, led, based lighting device

Abstract

An electronic device, comprising a housing, a substrate, provided in said housing, and having a top side and a bottom side, wherein said substrate comprises at least one electronic component provided at said top side of said substrate, and an Electromagnetic Interference, EMI, foam, wherein said EMI foam is provided such that said at least one electronic component is fully enclosed by said EMI foam in combination with said substrate.

Description

[0001] An electronic device having improved Electromagnetic Interference, EMI, shielding, as well as an associated Light Emitting Diode, LED, based lighting device

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to the field of electronic devices and, more specifically, to electronic devices that comprise an Electromagnetic Interference, EMI, foam for counteracting EMI.

[0004] BACKGROUND

[0005] Modem electronic devices often utilize substrates like printed circuit boards, PCBs, to house and interconnect a multitude of electronic components. As electronic systems become increasingly compact and interconnected, the need to address challenges such as Electromagnetic Interference, EMI, becomes more of importance. EMI refers to the undesired electromagnetic emissions or susceptibility that can adversely affect the performance of electronic components and nearby systems.

[0006] In the context of a printed circuit board assembly, the proximity and density of electronic components can increase any EMI-related issues. EMI may manifest in the form of radio frequency interference, electrical noise, and other electromagnetic disturbances, compromising the reliability and functionality of electronic devices surrounding the printed circuit board assembly.

[0007] Traditional approaches to mitigate EMI typically involve the use of shielding materials, grounded enclosures, and filtering components. However, these solutions may have limitations in terms of effectiveness, space utilization, heat conduction or cooling of critical components and cost. As the demand for high-performance and compact electronic devices continues to rise, there is a need for innovative solutions that address EMI challenges while minimizing the impact on overall system design, and increasing lifetime of electronic device.

[0008] The present disclosure aims to provide an electronic device having a substrate, wherein the electronic device incorporates novel and effective techniques for mitigating EMI, as well as for conducting heat from electronic components.

[0009] By enhancing the design and structure of the electronic device and its associated components, the present disclosure seeks to reduce electromagnetic emissions and / or susceptibility, thereby improving the overall electromagnetic interference of the electronic device, as well improving the electronic device lifetime.

[0010] SUMMARY

[0011] It would be advantageous to achieve an electronic device that has better Electromagnetic Interference, EMI, properties. It would further be advantageous to achieve a Light Emitting Diode, LED, based lighting device comprising such an electronic device.

[0012] In a first aspect of the present disclosure, there is provided an electronic device, comprising: a housing; a substrate, provided in said housing, and having a top side and a bottom side, wherein said substrate comprises at least one electronic component provided at said top side of said substrate; an Electromagnetic Interference, EMI, foam, wherein said EMI foam is provided such that said at least one electronic component is fully enclosed by said EMI foam in combination with said substrate.

[0013] The at least one electronic component at the top side of the substrate is fully enclosed by the EMI foam in combination with the substrate. This means that the electronic component is surrounded by a foam material. This is done for EMI shielding purposes. The foam serves as a EMI protective barrier and may operate as a heat conductive barrier around the electronic component, and the combination with the PCB indicates that it's integrated into the overall structure or assembly.

[0014] The electronic device may have one or more clock signals, frequency signals, control signals, or the like. These signals may have a frequency component. When electronic components on a substrate switch or transition between states, it can lead to the creation of harmonic frequencies that extend beyond the fundamental frequency of the signal. These harmonics can then radiate electromagnetic energy, potentially causing interference with other components or external devices.

[0015] Harmonics are multiples of the fundamental frequency of a signal, and their presence can result from non-linearities in electronic circuits. In the context of EMI, these harmonic frequencies can contribute to unwanted electromagnetic emissions, leading to interference issues. The present disclosure is directed to combatting EMI by utilizing an EMI foam such that the at least one electronic component is fully enclosed by the EMI foam in combination with the substrate.

[0016] The electronic component may be any type of electronic component, for example a transistor like a Field Effect Transistors, MOSFETs, an inductor, a capacitor, a resistor, diodes or anything alike.

[0017] In an example, said substrate further comprises at least one further electronic component provided at said bottom side of said substrate.

[0018] Wherein said EMI foam is provided such that said further at least one further electronic component provided at said bottom side of said substrate is also fully enclosed by said EMI foam in combination with said substrate.

[0019] The inventors have found that the bottom side of the substrate may also be occupied by one or more electronic components. The EMI foam may then also enclose those electronic components.

[0020] In an example, the housing is provided such that said housing in combination with said substrate fully encloses said at least one electronic component, wherein said EMI foam is provided at an inner side of said housing.

[0021] The EMI foam may be provided as a layer mounted to the inner side of the housing. The EMI foam may be sprayed to the housing, or an adhesive may be used to mount the EMI foam to the housing. The EMI foam may, or may not, contact the at least one electronic component.

[0022] In another example, the electronic device further comprises: a Thermal Interface Material, TIM, layer, provided at said at least one electronic component.

[0023] A Thermal Interface Material, TIM, is a type of material used to enhance the thermal conductivity between two surfaces, i.e. between the electronic component and the EMI foam. The primary purpose of a thermal interface material is to facilitate the efficient transfer of heat from one surface to another, ensuring effective thermal management and preventing overheating of electronic components.

[0024] Thermal interface materials are commonly applied between a heat-generating component, such as a microprocessor or power transistor, and a heat sink or another cooling device, via the EMI foam. The goal is to minimize the thermal resistance at the interface, allowing heat to be conducted away from the component and dissipated into the surrounding environment. Various types of thermal interface materials exist, including thermal greases, thermal pads, phase change materials, and thermal adhesives. Each type has its own characteristics and is chosen based on factors such as the specific application, thermal performance requirements, and ease of application.

[0025] In an example of the present disclosure, the TIM layer comprises cotton textiles.

[0026] The EMI foam may further comprise any of MXene, Graphene, MXene / Graphene Oxide, Carbon Nano Tube(NT), AgNT, CNTs, SiOC-ZrB2 Cellulose / chitosan / polyaniline, SiC, ITO, Cement / Ceramics, Boron Nitride (BN) foam.

[0027] In a further example, the EMI foam is a shape-memory foam.

[0028] A Shape-memory foam is a type of material that has the ability to "remember" and return to its original shape after being deformed. This unique property is a result of the material's composition, typically a viscoelastic polyurethane foam. The shape-memory foam could be also compressible foam or film or fiber with shape-memory coating. The term "shape-memory" refers to the material's capacity to undergo a reversible change in shape in response to external stimuli, such as heat or pressure.

[0029] The shape-memory foam can, for example, be deformed or compressed under certain conditions, such as through mechanical pressure or temperature changes. The shapememory foam can “remember” this deformation and stay in the deformed or compressed shape.

[0030] This ability to be shaped makes shape-memory foam useful in the electronic device in accordance with the present disclosure. The shape-memory foam can, for example, be provided all around, and against, the electronic component assuring an improved EMI shielding effect.

[0031] In a further example, the shape-memory foam is pressed against said at least one electronic component.

[0032] In another example, the at least one electronic component is one of a through- hole component and a surface mount device.

[0033] The distinction between through-hole components and Surface Mount Devices, SMD, lies in their mounting mechanisms on a substrate, for example a PCB. Through-hole components feature leads that are inserted through holes in the PCB, with soldering typically conducted on the opposite side of the board, creating a connection.

[0034] These components tend to be larger, requiring more space on the PCB, and their assembly often involves manual insertion followed by soldering. Conversely, SMDs are mounted directly onto the surface of the PCB without leads passing through holes. Solder joints are made on the same side as the components, and the smaller size of SMDs allows for higher component density on the PCB. The assembly of SMDs is often automated through processes like pick-and-place machines, which precisely position components for soldering.

[0035] In a further example, the device further comprises: a layer of electrical insulator provided to said at least one electronic component.

[0036] An insulator may be provided to said at least one electronic component to prevent any electrical connection between the at least one electronic component and the EMI foam.

[0037] In yet another example, the substrate further comprises: at least one further electronic component provided at a back side of said substrate.

[0038] The housing may be electrically non-conductive.

[0039] The EMI foam may be electrically floating, i.e. not electrically connected to ground.

[0040] In an example, the electronic device is a driver.

[0041] In yet another example, the driver is a driver for driving an Light Emitting Diode, LED, based lighting device.

[0042] In a second aspect of the present disclosure, there is provided a Light Emitting Diode, LED, based lighting device comprising an electronic device in accordance with any of the previous examples.

[0043] In the appended figures, similar components and / or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0044] The above and other aspects of the disclosure will be apparent from and elucidated with reference to the examples described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Fig. 1 discloses an example of an electronic device in accordance with the present disclosure;

[0046] Fig. 2 discloses another example of an electronic device in accordance with the present disclosure.

[0047] DETAILED DESCRIPTION

[0048] It is noted that in the description of the figures, same reference numerals refer to the same or similar components performing a same or essentially similar function.

[0049] A more detailed description is made with reference to particular examples, some of which are illustrated in the appended drawings, such that the manner in which the features of the present disclosure may be understood in more detail. It is noted that the drawings only illustrate typical examples and are therefore not to be considered to limit the scope of the subject matter of the claims. The drawings are incorporated for facilitating an understanding of the disclosure and are thus not necessarily drawn to scale. Advantages of the subject matter as claimed will become apparent to those skilled in the art upon reading the description in conjunction with the accompanying drawings.

[0050] The ensuing description above and below provides preferred exemplary embodiment s) only, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the preferred exemplary embodiment(s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment of the disclosure, it being understood that various changes may be made in the function and arrangement of elements, including combinations of features from different embodiments, without departing from the scope of the disclosure.

[0051] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, electromagnetic, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0052] Figure 1 discloses an example of an electronic device 1 in accordance with the present disclosure.

[0053] A shape-memory foam material 9 may be used to cover the driver compartment. The driver compartment is bounded by the housing 3 and the substrate 5. The EMI foam 9 can be used as adjustable EMI shielding thought self-fixable mechanical deformation.

[0054] The inventors have found that normal foam materials are not shapeable during heating up. This is not desired in sealing the EMI from electronics. Such a foam becomes compacted and takes over the topology of the components on the PCB due to thermal heating up.

[0055] The EMI foam in accordance with the present disclosure may be shapeable during heating up, such that the EMI foam can be formed around the at least one electronic component 7.

[0056] Further, optionally, a sustainable Thermal Interface Material, TIM, 11 may be utilized, which may be produced from recycled cotton textiles. The thermal conductivity of this TIM may be higher than the typical TIM or foam materials, i.e. x,y in plain 800W / mK, z through plane 5.5W / mK.

[0057] This TIM materials may be directly placed on the hottest components in the driver. At this point of time, TIM or metal heat sink, or potting and thermally conductivity pads may be used in cooling hot spots.

[0058] The TIM materials may be placed on the hottest components, then the shapememory foam may be pressed on the top of TIM and the PCB within the housing.

[0059] The EMI foam 9 can be placed all around the substrate 5 and the components

[0060] 7 mounted on the substrate. The EMI foam 9 then fully encapsulates the substrate 5 and components 7 so that electromagnetic radiation emitted from the components 7 is blocked or absorbed by the EMI foam 9 without having to provide any measured on the substrate 5 or any of the components 7. Preferably, the EMI foam 9 is a rigid foam. Such foam provides mechanical stability for the substrate 5 and components 7 against e.g. shock or vibrations.

[0061] The EMI foam 9 can be provided with a coating. The coating can be used to make the EMI foam 9 e.g. waterproof, UV resistant, dust resistant, electrical insulating, etc. Figure 2 discloses another example 21 of an electronic device in accordance with the present disclosure.

[0062] In this example, the EMI foam 9 is placed at the inside of the housing 3, covering the entire inner surface of the housing, besides any ports going out to e.g. a power source and a load. The EMI foam 9 still fully surrounds the at least one electronic component 7 and the substrate 5.

[0063] Further, optionally, a sustainable Thermal Interface Material, TIM, 11 may be utilized, which may be produced from recycled cotton textiles. The thermal conductivity of this TIM may be higher than the typical TIM or foam materials, i.e. x,y in plain 800W / mK, z through plane 5.5W / mK.

[0064] This TIM materials 11 may be directly placed on the hottest components in the driver. At this point of time, TIM or metal heat sink, or potting and thermally conductivity pads may be used in cooling hot spots.

[0065] The TIM materials 11 may extend all the way to the EMI foam 9 to provide a good thermal contact between the component 7 and the EMI foam 9.

[0066] It should be noted that the above-mentioned examples illustrate rather than limit the idea, and that those skilled in the art will be able to design many alternative examples without departing from the scope of the appended claims. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims.

[0067] Any reference signs in the claims shall not be construed so as to limit their scope.

Claims

CLAIMS:

1. An electronic device, comprising: a housing (3); a substrate (5), provided in said housing (3), and having a top side and a bottom side, wherein said substrate (5) comprises at least one electronic component (7) provided at said top side of said substrate; an Electromagnetic Interference, EMI, foam (9), wherein said EMI foam (9) is provided such that the substrate (5) and said at least one electronic component (7) are fully enclosed by said EMI foam (11).

2. The electronic device according to claim 1, wherein the EMI foam is rigid.

3. The electronic device according to claim 1, wherein the EMI foam comprises a coating.

4. An electronic device in accordance with any of the previous claims, wherein said housing is provided such that said housing in combination with said substrate fully encloses said at least one electronic component, wherein said EMI foam is provided at an inner side of said housing.

5. An electronic device in accordance with any of the previous claims, wherein said electronic device further comprises: a Thermal Interface Material, TIM, layer, provided at said at least one electronic component.

6. An electronic device in accordance with any of the previous claims, wherein said EMI foam comprises any of:MXene, Graphene, MXene / Graphene Oxide, Carbon Nano Tube, CNTs, SiOC-ZrEL Cellulose / chitosan / polyaniline, Silicon Carbide, SiC, Indium tin oxide, ITO, Cement / Ceramics, Boron Nitride, BN, foam.

7. An electronic device in accordance with any of the previous claims, wherein said EMI foam is a shape-memory foam.

8. An electronic device in accordance with any of the previous claims, wherein said device further comprises: a layer of electrical insulator provided to said at least one electronic component.

9. An electronic device in accordance with any of the previous claims, wherein said substrate further comprises: at least one further electronic component provided at a back side of said substrate.

10. An electronic device in accordance with any of the previous claims, wherein said housing is electrically non-conductive.

11. An electronic device in accordance with any of the previous claims, wherein said substrate is a Printed Circuit Board, PCB.

12. An electronic device in accordance with any of the previous claims, wherein said EMI foam is electrically floating.

13. An electronic device in accordance with any of the previous claims, wherein said electronic device is a driver.

14. An electronic device in accordance with claim 13, wherein said driver is a driver for driving an Light Emitting Diode, LED, based lighting device.

15. A Light Emitting Diode, LED, based lighting device comprising an electronic device in accordance with any of the previous claims.

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