权利要求：
1. An integrated functional multilayer structure comprising:
a flexible substrate film comprising at least a number of electrical conductors;
a lighting module provided upon the flexible substrate film, said lighting module comprising:
a circuit board for hosting electronics; and
circuitry arranged on the circuit board, the circuitry comprising at least one light source and/or at least one other electronic component;
a 3D-shaped sheet comprising thermally conductive sheet material at least thermally connecting to the circuit board, wherein the 3D-shaped sheet extends by its 3D-shape through the substrate film via a hole in the flexible substrate film;
a thermoplastic layer comprising one or more thermoplastic materials molded upon the flexible substrate film and at least laterally surrounding the lighting module;
wherein the circuitry on the circuit board of the lighting module is configured to electrically and thermally connect to a number of locations of the remaining multilayer structure beside or underneath the circuit board utilizing at least one connection material.
2. The structure of claim 1, wherein the at least one connection material comprises at least one material selected from the group consisting of:
electrically and thermally conductive material;
thermally conductive electrically insulating material; and
electrically conductive thermally insulating material.
3. The structure of claim 1, wherein the 3D-shaped sheet comprises electrically insulating material.
4. The structure of claim 1, wherein the 3D-shaped sheet comprises graphene.
5. The structure of claim 1, wherein the connection material, circuit board and/or the 3D-shaped sheet connected to the circuit board at least locally has a thermal conductance of at least about 1 W/mK.
6. The structure of claim 1, wherein the thermoplastic layer comprises optically at least translucent material.
7. The structure of claim 1, wherein the circuit board defines a tilted surface relative to the plane of the underlying substrate film for hosting at least part of the circuitry.
8. The structure of claim 1, comprising a carrier element for the circuit board disposed between the circuit board and the flexible substrate film, said carrier element comprising a beveled carrier surface for the circuit board aligning the circuit board in a tilted position relative to the plane of the underlying flexible substrate film.
9. The structure of claim 8, wherein the carrier beveled surface of the carrier element comprises a holder element matching with a compatible counterpart of the circuit board.
10. The structure of claim 8, wherein the carrier element comprises electrically and/or thermally conductive material.
11. The structure of claim 10, wherein the top of the carrier element facing away from the flexible substrate film defines an electrically conductive sensing electrode.
12. The structure of claim 1, comprising a side wall structure internally defining a cavity around the at least one light source and being laterally surrounded by the thermoplastic layer, said cavity comprising air, other fluid, or solid material, which is optically at least translucent to the selected emission wavelengths of the at least one light source.
13. The structure of claim 12, wherein the side wall structure is substantially opaque to at least selected wavelengths of the light emitted by the at least one light source.
14. The structure of claim 12, wherein the side wall structure substantially extends between the circuit board and the opposite surface of the thermoplastic layer.
15. The structure of claim 1, comprising at least one cover element on a side of the thermoplastic layer opposite to the side facing the circuit board.
16. The structure of claim 15, comprising:
a side wall structure internally defining a cavity around the at least one light source and being surrounded by the thermoplastic layer, said cavity comprising air, other fluid, or solid material, which is optically at least translucent to the selected emission wavelengths of the at least one light source; and
an adhesive layer between the side wall structure and the at least one cover element.
17. The structure of claim 1, comprising a lens structure including one or more lenses disposed along an optical path of the at least one light source.
18. The structure of claim 1, comprising a diffuser associated with at least one of the lighting module or the thermoplastic layer.
19. The structure of claim 1, comprising an electromagnetic interference shielding structure of electrically conductive material at least partially surrounding one or more elements of the circuitry.
20. The structure of claim 1, comprising at least one other element selected from the group consisting of: series resistor, thermistor, white solder mask, capacitor, inductor, trace, antenna, sensor, electrode, contact pad, integrated circuit, controller, processor, memory, transceiver, driver circuit, and via.
21. The structure of claim 1, wherein the circuit board comprises a number of castellations.
22. The structure of claim 1, where the at least one connection material defines an angular or curved element directed over an edge of the circuit board.
23. The structure of claim 1, wherein the flexible substrate film at least locally exhibits an essentially non-planar 3D shape.
24. The structure of claim 1, comprising structural adhesive between the substrate film and the circuit board.
25. The structure of claim 1, wherein the at least one light source comprises a packaged semiconductor type or a chip-on-board semiconductor type light source.
26. The structure of claim 1, wherein the circuit board comprises at least one element selected from the group consisting of: flexible film or sheet, rigid sheet, rectangular sheet or film, rounded or essentially circular sheet or film, FR4 based circuit board, metal core circuit board, plastic substrate, molded plastic substrate, metal substrate, and ceramic circuit board.
27. The structure of claim 1, wherein the flexible substrate film comprises at least one material selected from the group consisting of: polymer, thermoplastic material, electrically insulating material, PMMA (Polymethyl methacrylate), Poly Carbonate (PC), copolyester, copolyester resin, polyimide, a copolymer of Methyl Methacrylate and Styrene (MS resin), glass, Polyethylene Terephthalate (PET), carbon fiber, organic material, biomaterial, leather, wood, textile, fabric, metal, organic natural material, solid wood, veneer, plywood, bark, tree bark, birch bark, cork, natural leather, natural textile or fabric material, naturally grown material, cotton, wool, linen, silk, and any combination of the above.
28. The structure of claim 1, wherein the thermoplastic layer comprises at least one thermoplastic material selected from the group consisting of: polymer, organic material, biomaterial, composite material, thermoplastic material, thermosetting material, elastomeric resin, PC, PMMA, ABS, PET, copolyester, copolyester resin, nylon (PA, polyamide), PP (polypropylene), TPU (thermoplastic polyurethane), polystyrene (GPPS), TPSiV (thermoplastic silicone vulcanizate), and MS resin.
29. The structure of claim 1, wherein the at least one light source is a high-power component having a wattage of 1 W or more of electric power during use thereof.
30. A method for manufacturing an integrated functional multilayer structure, comprising:
providing a flexible substrate film with a circuit design comprising at least a number of electrical conductors;
arranging a lighting module upon the flexible substrate film, said lighting module comprising:
a circuit board for hosting electronics; and
circuitry on the circuit board and comprising at least one light source and/or at least one other high-power electronic component;
wherein the circuitry is configured to electrically and thermally connect to a number of locations of the remaining structure beside or underneath the circuit board utilizing at least one connection material;
arranging a 3D-shaped sheet comprising thermally conductive sheet material to at least thermally connect to the circuit board, wherein the 3D-shaped sheet extends by its 3D-shape through the flexible substrate film via a hole in the substrate film; and
producing a thermoplastic layer on the flexible substrate film to at least laterally surround the lighting module.
发明内容：
[0014]The objective of the present invention is to at least alleviate one or more of the drawbacks associated with the known solutions in the context of optically functional integrated structures and related methods of manufacture.
[0015]The objective is achieved with various embodiments of an integrated, functional multilayer structure and a related method of manufacture for providing the multilayer structure.
[0016]According to one aspect, an integrated functional multilayer structure comprises:
[0017]a flexible, preferably 3D-formable and thermoplastic, substrate film advantageously provided with a circuit design comprising at least a number of electrical conductors, such as traces and/or contact pads, further preferably at least partially if not fully additively printed thereon;
[0018]a lighting module provided upon the substrate film and preferably electrically connected to the circuit design thereon, said lighting module comprising:[0019]a circuit board for hosting electronics; and[0020]circuitry arranged on the circuit board comprising at least one light source, optionally comprising at least one LED or other optoelectronic light source and further optionally a compatible driver circuit such as a LED driver;
[0021]a thermoplastic layer comprising one or more thermoplastic materials molded upon the substrate film and at least laterally surrounding, optionally also at least partially covering, the lighting module;
[0022]wherein the circuitry on the circuit board of the lighting module including the at least one light source is configured to electrically and thermally connect to a number of locations of the remaining structure beside or underneath the circuit board, optionally including electrical traces and/or thermal conductors provided on the substrate film, utilizing at least one connection material positioned in between, preferably at least at the periphery of the circuit board.
[0023]In a further aspect, a method for manufacturing an integrated functional multilayer structure, comprises:
[0024]obtaining a flexible, preferably 3D-formable and thermoplastic, substrate film and preferably providing it, optionally at least partially by printed electronics technology such as screen printing or ink jetting, with a circuit design comprising at least a number of electrical conductors, such as traces and/or contact pads;
[0025]arranging, optionally as at least partially if not essentially fully pre-fabricated subassembly, a lighting module upon the substrate film, said lighting module comprising:[0026]a circuit board, such as a rigid fiberglass-reinforced epoxy-laminated circuit board or a metal core circuit board, for hosting electronics; and[0027]circuitry on the circuit board comprising at least one light source, optionally comprising at least one LED;[0028]wherein the circuitry is configured to electrically and thermally connect to a number of locations of the remaining structure beside or underneath the circuit board, optionally including electrical traces and/or thermal conductors provided on or adjacent the substrate film, utilizing at least one connection material positioned in between;[0029]and
[0030]producing, preferably through molding such as injection molding, a thermoplastic layer on the substrate film so as to at least laterally surround, optionally also at least partially cover, the lighting module.
[0031]The present invention provides different advantages over a great variety of previously applied solutions, naturally depending on each particular embodiment thereof.
[0032]For instance, thermal management such as thermal dissipation, or heat dissipation, between heat generating circuitry such as high-power LEDs included in the structure and the remaining structure potentially including particular thermal conductors and heat transfer elements may be considerably improved by the use of a circuit board-containing lighting module for hosting the circuitry and arranged thermal connections, for which there are many options deliberated hereinafter in more detail, between the circuitry and a number of locations of the remaining structure. Heat can be transferred and distributed effectively away from their generation points to avoid excessive hot spots that might damage besides adjacent elements such as the underlying substrate film also the heat sources such as LEDs or other circuitry themselves. Optimum heat transfer mechanisms naturally depend on the particular embodiment in question but generally include especially conduction and in some embodiments also e.g., convection or radiation.
[0033]Yet, by the suggested proper configuration such as feasible dimensions, shape, materials and element positioning of the circuit board of the lighting module, many previously annoying assembly, installation, reliability and interconnection issues regarding the related circuitry, potential other elements such as optical elements and the remaining (external) structure may be overcome or at least reduced.
[0034]The circuit board may generally have a rounded or essentially circular planar shape with castellated edges enabling convenient pad connection at the edges with the substrate film and elements thereon. Round shapes work well with overmolding while reducing also related need for e.g. mold flow simulations, and there are no requirements to assemble the part in or to some specific orientation. However, angular shapes such as rectangular shapes could be still alternatively used. As there does not have to be e.g., pads underneath the module, the module can be assembled or provided directly onto the film and often there is no need for underfill or extra protective layers, e.g. against heat or mechanical damage, such as ink layers between the substrate film and the module. Accordingly, as the circuit board may be firmly adhered directly to the substrate film, the board may be kept thin when desired (e.g. 0.2-0.6 mm thickness may be applicable). Thermal path to the remaining structure is minimized. Different cross-overs and passives may be done within the module. The module may be assembled without using e.g., any trench in a mold therefor. Achievable bonding is still strong, which may allow placing the circuit board and the whole module even directly under an injection molding gate or on or adjacent areas that are 3D shaped optionally by thermoforming. Resulting from all this, the number of necessary manufacturing phases is kept low, process speed high, and the resulting structure somewhat simple while effective and versatile when needed.
[0035]Having regard to electromagnetic disturbances commonly caused by e.g. electronic components such as LEDs, various embodiments of the present invention provide a solution by enclosing such EMI-causing components at least partially within an electrically conductive shield structure for blocking the associated electromagnetic fields. The structure may also be called as a Faraday cage. The shield structure may be cleverly implemented as integral or jointly with the lighting module. Separated ground, power and signal layers add to the EMI avoidance. The associated ground plane may be arranged to the circuit board and there may be connected, electrically conductive and preferably also optically reflective transverse walls on the sides. The used material may advantageously thus be both electrically conductive and optically reflective. The suggested type of an enclosure may be additionally or alternatively utilized to protect various EMI sensitive components such capacitive sensing elements such as drivers or different radio parts, for instance.
[0036]In various embodiments also light outcoupling from the structure may be improved in terms of accuracy, uniformity and intensity, for example, while undesired light leakage outside the structure or desired internal optical path is reduced. Besides through the usage of a suitable lightguide material such as translucent resin e.g. as the thermoplastic overmolding material, by the introduction of a sidewall structure in the lighting module, related internal cavity, lens or (micro)lens array, reflector, diffuser and tilted surface optionally arranged by a specific carrier element, light emitted by the included light sources may be effectively, reliably and accurately controlled and overall optical performance of the solution enhanced e.g., in the aforementioned respects. Yield of the associated manufacturing processes remains good or is elevated. The options listed above have clear synergetic effects while they may also be used selectively in each embodiment depending on the details of each particular use scenario and related constraints and requirements. Different embodiments of the present invention suit a great variety of illumination solutions including e.g. high intensity spotlight applications, surface or graphics illumination applications, backlighting, UI (user interface) lighting, ambient lighting, interior such as vehicle or specifically car interior lighting, etc.
[0037]With reference to the above, the used light sources may indeed be provided with carrier elements that enable orientating the sources as desired, thus offering a possibility to adjust their emission directions and resulting outcoupling areas in terms of their position and size, for example, rather flexibly. For instance, a top-shooting (top-emitting) light source may be tilted such that its beam is laterally shifted from directly above the light source towards the side(s). As many of feasible thermoplastic materials, such as materials used for lightguides, have a lowish injection molding temperature, use of e.g., IMSE technology may be made more reliable and yield improved in contrast to materials requiring high molding temperatures easily negatively affecting the functionality and condition of features already existing on substrate films or other elements subjected to such temperatures.
[0038]The selected thermoplastic overmolding material and/or other material(s) included in the structure, optionally specifically in the module, and used e.g., as lightguides may be selected essentially transparent or translucent (i.e. scattering/diffusive as multiple scattering can be deemed diffusion) so that the illumination effect obtained by an embedded light source e.g., on a selected target surface of the structure, e.g. exterior surface, which may contain e.g. an icon or other graphical element to be illuminated by the outcoupled light, is uniform without obvious hot spots or dark areas, while still avoiding noticeable or at least excessive light leakage to adjacent areas, which may be optionally associated with different light source(s) and target features such as icons to be illuminated separately.
[0039]Generally, in various embodiments a selected optically attenuating (scattering (diffusive) and/or absorbing) translucent and potentially tinted or more strongly colored material such as thermoplastic resin, may be utilized as the light carrier, or “lightguide”, material to control light propagation and limit it to desired areas and distances while avoiding substantial leakage to non-desired areas called light leakage prohibition regions. Accordingly, different surfaces, icons, symbols, shapes, other features and structures may be effectively and controllably illuminated while not exposing non-target areas, even close or adjacent ones, to similar lighting. This facilitates providing highly integrated smaller size structures wherein different features can be located close to each other without causing mutual issues such as light leakage or electromagnetic disturbance due to their shortish distance.
[0040]The color, translucency, diffusion and generally optical attenuation properties of the used material(s), such as the thermoplastic material(s), may be configured by mixing additives such as a selected masterbatch or pigment based color additive therein, for instance. Yet, the material(s) of the thermoplastic layer or further layer(s) may locally vary even within the very same integral or even monolithic layer or piece in terms of associated characteristics such as attenuation or particularly diffusion, obtained by varying the material properties such as a mixing ratio during manufacturing or application thereof.
[0041]Various embodiments of the present invention may further enable providing, by clever joint configuration of the used materials, light sources, and e.g. their mutual positioning, orientation as well as dimensions, a so-called “hidden until lit” effect e.g., in the IMSE structures. Graphical symbols provided in the structure, various components, or e.g., conductive traces can be obscured from external visual perception until a light source intended and targeted to illuminate them is activated. With such embodiments of the present invention, it is possible to have decorative surface prints on the outcoupling areas and e.g. on associated film(s) (not just openings), and by embedding features to be normally masked from easy external visual perception e.g., several millimeters deep in the lightguide material, related optical aspects are much more convenient to control than with very shallow layers. The suggested solution is also time and cost saving process-wise.
[0042]Various other advantages different embodiments of the present invention may offer will become clear to a skilled person based on the following more detailed description.
[0043]The expression “a number of” may herein refer to any positive integer starting from one (1).
[0044]The expression “a plurality of” may refer to any positive integer starting from two (2), respectively.
[0045]The terms “first” and “second” are herein used to distinguish one element from other element(s), and not to specially prioritize or order them, if not otherwise explicitly stated.
[0046]The exemplary embodiments of the present invention presented herein are not to be interpreted to pose limitations to the applicability of the appended claims. The verb “to comprise” is used herein as an open limitation that does not exclude the existence of also un-recited features. The features recited in various embodiments and e.g. dependent claims are mutually freely combinable unless otherwise explicitly stated.
[0047]The novel features that are considered as characteristic of the present invention are set forth in particular in the appended claims. The present invention itself, however, both as to its construction and its method of operation, together with additional objectives and advantages thereof, will be best understood from the following description of a number of specific embodiments when read in connection with the accompanying drawings.
具体实施方式：
[0064]FIG. 1 illustrates, at 100, an embodiment of a multilayer structure in accordance with the present invention.
[0065]The multilayer structure includes at least one substrate film 102, which is preferably of flexible and 3D-formable (3D-shapeable) material, such as thermoformable (plastic) material. As being easily comprehended by a person skilled in the art, instead of a single, optionally monolithic film 102, the substrate film 102 could be of a multilayer and/or multi-section construction with mutually different layers at least in places, for instance.
[0066]Item 108 refers to at least one thermoplastic, functionally lightguide establishing, layer preferably provided by molding it upon the substrate film 102 and optionally essentially between the substrate film 102 and element 120, which may be another (substrate) film either different from or similar to the film 102, for example.
[0067]The lightguide layer 108 comprises a first side and a related first surface 108A that is advantageously targeted towards the use environment of the structure and e.g., a user of the structure, or a device containing the structure, therein. Yet, the substrate film 102 comprises an opposite second side and associated second surface 108B essentially facing the structure internals or a host device, for instance.
[0068]As alluded to hereinbefore, item 120 may refer to at least one further film, coating, or other functional element. In many embodiments, there may be multiple of such at least locally stacked upon the surface 108A.
[0069]The substrate film 102 and/or further film(s) 120 or generally material layer(s) included in the multilayer structure may comprise at least one material selected from the group consisting of: polymer, thermoplastic material, electrically insulating material, PMMA (Polymethyl methacrylate), Poly Carbonate (PC), flame retardant (FR) PC film, FR700 type PC, copolyester, copolyester resin, polyimide, a copolymer of Methyl Methacrylate and Styrene (MS resin), glass, Polyethylene Terephthalate (PET), carbon fiber, organic material, biomaterial, leather, wood, textile, fabric, metal, organic natural material, solid wood, veneer, plywood, bark, tree bark, birch bark, cork, natural leather, natural textile or fabric material, naturally grown material, cotton, wool, linen, silk, and any combination of the above.
[0070]The thickness of the film 102 and optionally of further film(s) or layer(s) 120 may vary depending on the embodiment; it may only be of few tens or hundreds of a millimeter, or considerably thicker, in the magnitude of one or few millimeter(s), for example.
[0071]The thickness of the thermoplastic layer 108 may also be selected case-specifically but thicknesses of few millimeters, such as about 3-5 millimeters, may be applied. In some embodiments, only about 2 millimeter thickness could be sufficient if not optimum, while in some other embodiments the thickness could be considerably more as well, e.g. about 1 cm or more at least in places. The thickness may indeed locally vary. The thermoplastic layer 108 may optionally comprise recesses or internal cavities for light guiding, processing, and/or thermal management purposes, for instance, in addition to accommodating various elements such as electronic or optical elements.
[0072]Item 110 refers to a lighting module provided upon the substrate film 102 and preferably electrically connected to the circuit design thereon. The lighting module 110 comprises at least a circuit board 112 for hosting electronics and circuitry 114 arranged on the circuit board comprising at least one light source, optionally comprising at least one LED such as a high-power LED. The circuitry 114 on the board 112 will preferably also include a circuit design with e.g. conductive traces or pads for connecting components such as light sources with other components or elements, e.g. control or communication circuit, in a desired fashion at least locally on the board 112.
[0073]The wattage of one or more light sources of the at least one light source and/or of some other high-power component included may be about 1 W or more, even significantly more, for example. Optionally, there may be a plurality of light sources of mutually similar or different characteristics (wavelength/color, power, emission direction, beam width, technology, etc.) on the board 112. An included light source such as a LED may be preferably independently adjusted e.g., in terms of its emission intensity via compatible control and driver circuit preferably at least partially included in the same multilayer structure and more preferably in the same module 110, utilizing e.g. PWM (pulse width modulation) or current control for the purpose.
[0074]Item 103 refers to the circuit design in the form of a number of electrical, optionally additively printed such as screen printed, conductors such as traces, which may optionally further act as thermal conductors. They 103 may be used for power and data transfer purposes, for example, between the elements of the structure 100 and/or with external elements. Item 104 refers to a number of thermal conductors such as thermal traces. Preferably, they may be at least partially provided as the electrical conductors, with reference to printing and other applicable methods. Likewise, the thermal conductors 104 may optionally be also electrically conductive.
[0075]There may be circuitry going beyond the circuit design of conductive traces or pads 103, such as various components 115, e.g. light source(s) or other electronic or specifically optoelectronic components, also outside the module 110. This circuitry could be provided upon any of film(s) 102, 120 and/or other layers, potentially still at least partially embedded in the thermoplastic layer 108. Indeed, in case the structure contains e.g. a further film 120, it 120 could be provided with circuitry including e.g., light source(s) or sensor(s) as well, and be optionally electrically or electromagnetically connected to the electronics such as traces and components on the film 102 via intermediate wiring or wirelessly through capacitive or inductive coupling, for instance.
[0076]In the shown case, the (first) light source is emissive as indicated by the dotted lines extending from the source 104 to a target outcoupling area 118 on the layer 108. It 104 may be e.g., a top-shooting LED.
[0077]Generally in various embodiments of the present invention, the used light source(s) included e.g. in circuitry 114 could be any of top-emitting, side-emitting, dual side emitting, and bottom emitting light source(s) such as LEDs, for example. Using e.g. a side-emitting light source, the outcoupling area 118 may be conveniently laterally shifted from the area right above the light source 104 on the surface 108A.
[0078]A packaged semiconductor type or a chip-on-board semiconductor type light source, preferably LED, may be used. Still packaging-wise, the light source could be optionally of flip-chip type. In some embodiments, the light source may contain multiple (two, three, four, or more) light-emission units such as LEDs packaged or at least grouped together. For example, a multi-color or specifically RGB LED of several LED emitters could be provided within a single package.
[0079]In preferred embodiments, the optical transmittance of e.g., translucent material selected for the thermoplastic layer 108 may be between about 25% and about 90%, or more, at selected wavelengths such as at least part of the visible wavelengths, considering e.g., about 2 mm or 3 mm thick sample of the material. The associated half power angle can be between about 5 and about 75 degrees (intensity based), such as about 5, 10, 20, 30, 40, 50, 60, or 70 degrees. In different use scenarios, desired transmittance and scattering characteristics may naturally still vary.
[0080]Accordingly, the thermoplastic layer 108 may comprise optically at least translucent, optionally substantially transparent, material, wherein the optical transmittance of the overall thermoplastic layer may in some use scenarios preferably be at least 50%, but the desired transmittance may indeed radically differ between all possible use scenarios. In some embodiments at least about 80% or 90% transmittance could be preferred for maximizing the light output from the structure, while in some others 10%, 20% or 30% could be quite sufficient if not even advantageous, if e.g. light leakage related issues are to be minimized. The transmittance may be measured or defined in a selected direction, e.g. main direction of light propagation and/or in a transverse direction to the surface of the substrate film at the position of the lighting module on the substrate film, having regard to selected wavelengths, optionally including visible wavelengths, of the light emitted by the at least one light source.
[0081]Suitable translucency and attenuation of the thermoplastic layer 108 may be reached by employing scattering elements in the lightguide material, for example. When the amount of scattering elements is increased, scattering/diffusion and half power angle, as one possible measurable indicator, are increased as well while luminous transmission through the layer will generally decrease. Correspondingly, increasing layer thickness generally increases scattering/diffusion properties such as the half power angle and decreases transmission.
[0082]While considering e.g. the scattering/diffusion or other optical properties as discussed above, the thermoplastic layer 108 may generally comprise, for example, at least one material selected from the group consisting of: polymer, organic material, biomaterial, composite material, thermoplastic material, thermosetting material, elastomeric resin, PC, PMMA, ABS, PET, copolyester, copolyester resin, nylon (PA, polyamide), PP (polypropylene), TPU (thermoplastic polyurethane), polystyrene (GPPS), TPSiV (thermoplastic silicone vulcanizate), and MS resin.
[0083]One example of a polycarbonate based applicable material is Makrolon™ available in a variety of grades, exhibiting different colors/tinting (e.g. white/whitish and black/blackish or dark), transparencies and scattering characteristics, for example.
[0084]As discussed above, tinted or more strongly colored resin may provide a feasible option for the thermoplastic layer 108 to limit undesired light leakage within and outside the structure 100 to close elements or generally distances, and hide the internals such as light source 104 or other circuitry from external perception. Originally optically substantially clear base material such as PC or other plastic resin may be doped with a colored masterbatch. In many use scenarios wherein the structure 100 should be only e.g., few millimeters or a centimeter thick in total, whereupon the thermoplastic layer 108 should be even thinner, using about 2-4 mm, such as 3 mm, thick layer of plastic resin provided with a selected masterbatch (e.g. white or desired selective wavelength resin, optionally also e.g. IR (infrared) resin that might find use e.g., IR remote control applications) in a desired concentration (e.g. let-down ratio of about 1%) for establishing the lightguide layer 108, may provide quite satisfying results. Generally, in many embodiments in the context of the present invention, a feasible let-down (dosing or doping) ratio is indeed about 5%, 4%, 3%, 2%, 1% or less. For example, suitable industrial grade masterbatches for the purpose are provided by Lifocolor™.
[0085]The afore-discussed “hidden until lit” effect may be achieved, for instance, by adding translucent, e.g. a selected color exhibiting, masterbatch in the injection molded base resin constituting the lightguide layer 108. Yet, the used substrate film 102 may be opaque, black and/or otherwise exhibitive of dark colour. Accordingly, it is possible to provide “invisible until lit icons” on the surface 108A, with reference to e.g., printed elements 122, clear or translucent film 120 with printed icons, and/or an opaque/dark/color film arranged with one or more openings among other options. Using e.g. about 3% of translucent, preferably black color masterbatch may be sufficient to visually hide underlying modules 110, components 115, traces 103, and/or other elements from external perception. The embedded underlying elements such as components and traces may be additionally prepared from dark color—providing, preferably optically highly attenuating or absorbing materials. Alternatively, transparent materials could be utilized. Different illumination effects may be achieved with different colors. The translucent material of the layer 108 may be generally or selectively matched to the color(s) used on the surface 108A, such as the color(s) exhibited by the inks or films thereat.
[0086]As mentioned above, using essentially white color exhibiting resin as the layer 108 and with a suitable configuration of multi-color light sources such as RGB-LEDs embedded, basically any color may be lit upon need on the (white) surface 108A.
[0087]Item 130 refers to optional encapsulant, glob top or other conformal coating, such as a Illumabond™ or Triggerbond™ for light shaping or other processing, protecting and/or securing purposes, for instance. The used substance may be dispensed on top of selected circuitry 114 such as the light source. It may be substantially clear (transparent), for example. Alternatively, it could be colored and/or translucent. In some embodiments, a specific optical function or feature such as a lens may be provided by the encapsulant. The lens could be diffusive, Fresnel or e.g. collimating, for example. Additionally or alternatively, a pre-made lens or generally optical component is possible to include in the structure as well. Various potential lens implementations are discussed also hereinlater.
[0088]As briefly alluded to above, item 122 may refer to at least one functional element that may have been attached and/or additively in-situ produced such as printed (e.g., screen printed, inkjetted, or 3D printed) on the first surface 108A of the thermoplastic layer 108, optionally positioned adjacent and/or upon the outcoupling area 118. In case there is also e.g., a film 120 on the surface 108A, a functional element 122 could have been provided on any side thereof, i.e. the side facing the layer 108 or the opposite side thus facing the environment. On the side facing the layer 108 it 122 would be better protected from the environment.
[0089]The functional element(s) 122 may be selected from the group consisting of: light blocking (masking) element, graphical element (e.g., icon, symbol, pattern, alphanumeric element, picture, etc., which may have an indicative nature such as status indicator of a hosting or connected device), optical diffuser, reflector, dispersive element, and collimator. Optically the functional element(s) 122 as well as e.g., film(s) 102, 120 may be transparent, translucent or opaque, with reference to e.g. color prints or layers. Yet, the item 122 may refer, for example, an electrically and/or thermally conductive trace, electrode, electrical insulator, electronic component, circuit element, or a connector.
[0090]In some embodiments, the functional element(s) 122 could be monolithic with the layer 108 as discussed hereinelsewhere.
[0091]Thus the functional element(s) 122 may have, among other options, indicative, optical, connecting, thermal, and/or electrical (conductive, insulating, sensing or other) function, for instance.
[0092]Based on the foregoing, it may be thus said that in this and various other embodiments of the multilayer structure and module 110, at least one cover element, optionally including at least one further film and/or printed element, 120, 122 on a side 108A of the thermoplastic layer opposite to the side 108B facing the circuit board, may be provided. The at least one cover element may host or define one or more target elements 118, 118B, optionally comprising symbols, icons, textures, 3D surfaces, or surface (sub-)areas, to be illuminated by the at least one light source of circuitry 114 and/or 115.
[0093]As already alluded to above, the element(s) 122 may be positioned e.g., adjacent the outcoupling area 112 or partially or fully overlapping therewith. The light source(s) included in circuitry 114 may be configured to illuminate the element(s) 122 such as graphical elements in a way that they stand out visually to a user in the environment of the structure 100. Further light sources potentially included in the structure 100 may have a similar function in terms of the outcoupling areas/functional elements associated therewith (which may differ or be the same as with the first source 104) as already discussed hereinbefore. In some embodiments, a plurality of light sources included may be configured to jointly establish an illuminated element, such as a figure, pattern, symbol, icon, or animation, optionally with one or more elements 120, 122 and/or (selected features of) thermoplastic layer 108 for external perception.
[0094]The circuitry 103, 114, 115 included in the structure 100 (e.g., in the module 110 or elsewhere), besides a number of light source(s) and e.g. related drivers, may comprise e.g., the aforementioned electrically conductive traces 103 or contact pads optionally printed on the film 102 and/or other material layers of the structure 100 using printed electronics technology. The traces may be configured for power and/or data (e.g. signaling data or other data) transfer between elements such as a light source and related driver, or generally a controller and/or power source, for example. Yet, the circuitry may comprise one or more electrodes, electrical connectors, electronic components and/or integrated circuits (IC), such as control circuits or data transfer circuits. Such circuitry may be directly produced in or for the structure 100 by selected method(s) such as a selected printed electronics technology, optionally screen printing, or using a selected coating technique, for instance. Additionally or alternatively, the circuitry may include a number of mounted components such as surface-mounted devices (SMD). Accordingly, non-conductive and/or conductive adhesive may be utilized for securing the components on the carrier. In some embodiments, mechanical securing is implemented or at least enhanced by nonconductive adhesive material whereas solder or other electrically highly conductive (but to lesser extend, adhesive type of) material is used for electrical connection.
[0095]If optionally capacitive sensing of e.g., touch or touchless gestures upon the structure 100 is to be implemented, sensing electrodes of the circuitry may be configured (dimensioned, positioned, etc.) so that their sensing area or volume defined by e.g., the associated electric or electromagnetic field is located as desired and thereby covers e.g. the area upon selected side walls and/or top of the structure, and/or other regions that should be made sensitive to touch (and/or touchless gestures in some embodiments) or other sensing target. This type of configuring may be achieved or performed through the utilization of necessary simulation or measurements, for instance.
[0096]Still, the circuitry may comprise and/or the remaining multilayer structure may comprise at least one component or element selected from the group consisting of: electronic component, electromechanical component, electro-optical component, radiation-emitting component, light-emitting component, LED (light-emitting diode), OLED (organic LED), side-shooting LED or other light source, top-shooting LED or other light source, bottom-shooting LED or other light source, radiation detecting component, light-detecting or light-sensitive component, photodiode, phototransistor, photovoltaic device, sensor, micromechanical component, switch, touch switch, touch panel, proximity switch, touch sensor, atmospheric sensor, temperature sensor, pressure sensor, moisture sensor, gas sensor, proximity sensor, capacitive switch, capacitive sensor, projected capacitive sensor or switch, single-electrode capacitive switch or sensor, capacitive button, multi-electrode capacitive switch or sensor, self-capacitance sensor, mutual capacitive sensor, inductive sensor, sensor electrode, micromechanical component, UI element, user input element, vibration element, sound producing element, communication element, transmitter, receiver, transceiver, antenna, infrared (IR) receiver or transmitter, wireless communication element, wireless tag, radio tag, tag reader, data processing element, microprocessor, microcontroller, digital signal processor, signal processor, programmable logic chip, ASIC (application-specific integrated circuit), data storage element, and electronic sub-assembly.
[0097]The structure 100 may be and in many use scenarios will be connected to an external system or device such as a host device or host arrangement of the structure, wherein the connection may be implemented by a connector, e.g. electrical connector, or connector cable, which may be attached to the structure 100 and its elements such as circuitry in a selected fashion, e.g. communications and/or power supply wise. The attachment point may be on a side or bottom of the structure, provided e.g., via a through-hole in the film 102. These aspects are discussed further also hereinafter.
[0098]Item 124 refers to fixing element or material such as structural adhesive that may be disposed between the substrate film 102 and the circuit board 112 to enable securing the board 112 and therefore the module 110 containing board 110.
[0099]Item 116A refers to electrical connection material, i.e. at least electrically conductive material, which may optionally also be thermally conductive.
[0100]Item 116B refers to thermal connection material, i.e. at least thermally conductive material, which may optionally also be electrically conductive.
[0101]Electrical and thermal connection points and/or routes may be the same or mutually different at the structure 100, e.g., between the module 110 (circuit board 112, circuitry 114) and the remaining structure (e.g. traces 103 of the circuit design, thermal conductors 104, various other circuitry 115, heat transfer elements, etc.) and/or locally e.g. within the module 110, or on the film 102.
[0102]Commonly, the used material 116A, 116B may be conductive both thermally and electrically, whereupon depending on the particular use case, a person skilled in the art may determine whether e.g. a dominantly electrically conductive material with lower thermal conductivity still suffices as a thermal connection material, or vice versa, or should different materials or composite materials be used for obtaining desired conductivity in both respects.
[0103]Accordingly, one or more connection materials may be used to provide the desired electrical and thermal connections between the module 110 and the remaining structure such as circuit design/circuitry 103, 115 on the film 102 or elsewhere, thermal conductor(s) 104 and/or e.g. potential further heat transfer element(s) discussed hereinafter e.g. with reference to FIGS. 6-8.
[0104]The at least one connection material 116A, 116B thus advantageously comprises at least one material selected from the group consisting of:[0105]electrically and thermally conductive material such as ink or adhesive;[0106]thermally conductive electrically insulating material such as adhesive; and[0107]electrically conductive thermally insulating material.
[0108]At least thermally conductive connection material, circuit board and/or a heat transfer element connected to the circuit board may preferably have, still depending on the embodiment and at least locally if not generally, a thermal conductance of at least about 1 W/mK, more preferably at least about 10 W/mK, and most preferably at least about 100 W/mK.
[0109]Electrical conductivity of materials included in the structure due to their good electrical conductivity or correspondingly, low electrical resistance, considering e.g. at least electrically conductive connection material or generally various other elements to be used at least as electrical conductors such as traces, pads or electrodes, may vary depending on the embodiment. When defined in terms of sheet resistivity, the sheet resistivity of the used material may at least locally, if not generally, be e.g., about 350 mΩ/sq/mil or less, more preferably about 100 mΩ/sq/mil or less and most preferably about 35 mΩ/sq/mil or less on a substrate material such as a polycarbonate film. One practical example of industrial grade suitable material is e.g., Dupont™ ME602 or ME603 silver conductor, which is also stretchable and therefore suits applications requiring 3D shaping by thermoforming well.
[0110]The at least one connection material 116A, 116B may define an angular or curved element directed e.g., over an edge of the circuit board 112 (“edge connector”). Alternatively or additionally, the connection material 116A, 116B, or the connection element created therefrom, may in some embodiments proceed through the circuit board 112 via a through-hole therein, for example. The element may generally also be straight (e.g. bar or pipe-like) or exhibit a dome, ball, blob or other shape depending on e.g. provision method thereof, such as dispensing. For instance, shapes reminding of letters L, U, I or O are possible. In some embodiments, any of connection elements created by the connection material 116A, 116B could be formed at least partially integrally with some other element of the multilayer structure such as board 112, circuitry 114, conductor 103, 104, or castellation 212.
[0111]FIG. 2 illustrates at 200, via a top or plane view, an embodiment of a lighting module 110 comprising a circuit board 112 provided with circuitry 114 in accordance with the present invention.
[0112]The circuit board 112 may comprise at least one element selected from the group consisting of: a flexible film or sheet, a rigid sheet, rectangular sheet or film, rounded or essentially circular sheet or film, FR4 based circuit board, metal core circuit board, plastic substrate, molded such as injection molded plastic substrate, metal substrate such as sheet metal substrate optionally having an electrically insulated layer at least selectively provided thereon, and a ceramic circuit board.
[0113]As discussed also hereinbefore, the circuit board 112 or e.g., the substrate film 102 may host various electrical and/or other elements, such as series resistor, thermistor, white solder mask, trace, antenna, sensor, electrode such as a capacitive sensing electrode, contact pad, integrated circuit, controller, processor, memory, transceiver, driver circuit, optionally optically clear glob top or other conformal coating, and via such as electrical, fluidic and/or thermal via.
[0114]Series resistors may be used to even out undesired resistance fluctuation arising from printed electronics, for example. A thermistor may turn out useful in preventing overheating situations, which might damage different components and materials such as thermoplastic layer 108. White soldermask may be utilized to improve the reflectivity of the associated surface. Yet, exposed conductive area with immersion silver or gold surface finish may be utilized. For example, gold is excellent reflector for IR applications, whereas silver works well for visible light. Exposed copper could be used e.g., at the bottom for enhancing adhesion and thermal conductivity. Vias may be beneficial in a number of ways depending on their configuration, with reference to creating thermal bridges for thermal (heat) dissipation purposes, reducing the amount of trapped air under the concerned element during injection molding, for instance, and enhancing the adherence of the concerned element to a carrier surface such as the substrate film 102. Capacitors (or inductors) may be utilized e.g. for current control purposes such as fluctuation control.
[0115]The circuit board 112 preferably comprises a number of castellations 212. Plated half-holes or plated edges are feasible options among others. The number of desired castellations may vary case-specifically from a few to several tens, for example. A number of extra castellations may be provided for redundancy to meet e.g., safety compliance or failure rate requirements. The diameter of a castellated hole may be about 1 mm or less, for instance. The castellations 212 may be then provided with the at least one connection material 116A, 116B such as electrically/thermally conductive adhesive or ink. Accordingly, the castellations or castellated holes 212 may be configured to provide both electrical and thermal connectivity having regard to the board 112 and module 110 general vs the remaining structure.
[0116]Generally, the circuit board 112 may be planar and preferably round if not essentially circular or elliptical by its general shape. The dimensions, shapes and thickness of the circuit may vary depending on the use case. Therefore, e.g. rectangular shape is possible as well. Thickness may be a fraction or portion of a millimeter (e.g. between about 0.2 and about 0.6 mm), a millimeter, few millimeters, or more, for example. Yet, the diameter may be few millimeters, about one centimetre, or few centimeters among other options.
[0117]To avoid e.g. CTE (coefficient of thermal expansion) related issues such as cracking, it may be useful to maintain the board 112 a bit smaller or moderate in terms of its size, and increase other thermal dissipation area/volume in the structure by providing thermal elements such as prints therein, for example. Yet, a thicker board 112 may facilitate providing the hosted circuitry 114 and/or other elements, such as optics or touch sensors, closer to the surface 108A, which may improve light outcoupling among other potential benefits, while a thinner board 112 may improve at least heat dissipation to the elements underneath.
[0118]As discussed also hereinelsewhere, the circuitry 114 on the circuit board 112 may be configured to electrically and thermally connect to a number of locations of the remaining multilayer structure e.g., beside or underneath the circuit board 112, utilizing at least one connection material 116A, 116B positioned in between, preferably at least at the periphery of the circuit board 112 (if present) and optionally through it.
[0119]As already contemplated hereinbefore, the use of the circuit board 112 may facilitate besides various assembly related issues also thermal management in connection with heat generating elements such as high power light sources, optionally high power LEDs. Damaging the substrate film 102 by excessive heat build-up by the electronics may be then avoided or at least reduced among other benefits; the circuit board 112 could itself act as a heat sink among other features potentially included in the structure 100 for the same purpose.
[0120]FIG. 3 illustrates an embodiment of a carrier element usable in connection with the present invention.
[0121]However, prior to discussing the details of FIG. 3 and generally relating to available options for positioning and orienting of one or more of the light source(s) of the structure 100 as desired in terms of their illumination characteristics, for example, it shall be mentioned that a light source may be tilted, relative to a reference such as the top surface 108 of the arrangement or the original plane of the substrate film 102, by 3D shaping, optionally through thermoforming, the hosting substrate film 102 so as to establish at least a local 3D shape such as protrusion or recess at the location of the source, thus also tilting the source. Accordingly, emission direction(s) of the source may be adjusted in a desired way. For example, a top-shooting light source could be adjusted to hit or shoot further away on the surface 108A (e.g. an icon or other graphical/functional element 122 could be conveniently illuminated from side, whereas the volume directly below the illuminated feature may be optionally utilized for other purpose, e.g. electronics for sensing or other uses). A side-shooting light source could be additionally or alternatively adjusted to illuminate areas closer on top of it. Therefore, depending on the embodiment, tilting may also facilitate illumination of larger or smaller areas than otherwise being possible, and/or obtaining better uniformity to the surface illumination.
[0122]However, FIG. 3 illustrates, at 300, an alternative or supplementary solution. Here the circuit board