WO2016020782A1

WO2016020782A1 - A support structure for lighting devices, corresponding device and method

Info

Publication number: WO2016020782A1
Application number: PCT/IB2015/055490
Authority: WO
Inventors: Andreas Lovich; Klaus Eckert; Alessio Griffoni; Ilario MARONESE; Franco Zanon; Markus Hofmann; Steffen Tegethoff
Original assignee: Osram Gmbh; Osram S.P.A. - Societa' Riunite Osram Edison Clerici
Priority date: 2014-08-05
Filing date: 2015-07-20
Publication date: 2016-02-11

Abstract

A support structure for lighting devices, e.g. LED lighting devices, includes: - a non-flat substrate (10a, 10b) made of a flat laminar member (10) subjected to bending, and - an electrical power supply circuit (12) formed on said substrate. The non-flat substrate (10a, 10b) includes first portions exhibiting bending-induced strain and second portions (10a) exempt from bending-induced strain. The electrical power supply circuit (12) is formed at locations of the non-flat substrate (10a, 10b) which are included in the portions which are exempt from bending-induced strain.

Description

"A support structure for lighting devices, corresponding device and method"

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Technical Field

The present description refers to lighting devices .

One or more embodiments may refer to lighting devices which employ, as light radiation sources, electrically powered light radiation sources; they may be for example solid-state radiation sources, such as LED sources.

Technological Background

In designing LED lighting devices (lamps, "luminaires", LED modules etc.) a cooling surface may be provided to enable the operation of the LED junction at high temperatures.

LEDs of medium/high power may be provided with heatsinks, which are adapted to spread a point-shaped temperature load over a larger surface which may be cooled for example through air ventilation, through diatermic fluids or by conveying the heat towards housings or other structures of the lighting device. In order to be assembled to LED modules, such a heatsink may also be coated directly with an Insulated Metal Substrate (IMS) .

In order to achieve a compact assembly, LED modules may be provided with a heatsink having a non- flat shape (i.e. a 3D shape), for example of a metal material as aluminium, which may lead to the achievement of both a compact assembly and a good heat diffusion. The possibility is moreover offered to enable the mounting on a luminaire, and/or the mechanical and thermal coupling with other elements such as a thermally conductive plastic housing, a diffuser and/or a reflector (e.g. a PMMA reflector with a reflective coating) . In some implementations, the shape of the heatsink may enable the mounting on the heatsink of the so-called Printed Board Assembly (PBA) .

Some LED modules may be provided with an Electronic Control Gear (ECG) which may be arranged e.g. in the same lamp wherein the LED module is mounted. In some embodiments, the ECG circuit may be located immediately below the heatsink and, in order to prevent the system (e.g. the LED module and the ECG circuit) from undergoing temperature-induced failures, the heatsink may be designed based on a tradeoff between the dissipation of the heat generated by the LEDs and an increase of temperature caused in the ECG circuit by the thermal dissipation of the LEDs.

Another possible factor to be taken into consideration is the overall cost of the LED module; this may lead to use, for example, moulded heatsinks or heatsinks made of metal sheet in two or more parts, which affects both the Bill Of Materials (BOM) and the costs of the manufacturing process.

Implementations aiming at dealing with the above- mentioned aspects may involve the use of a standard PBA assembly, with the LEDs, the connectors and the other electronic components being arranged on a flat Printed Circuit Board (PCB) , for example of the Insulated Metal Substrate (IMS) kind. The PBA assembly thus formed may be mounted via conductive adhesives, bi-adhesive Thermal Interface Materials (TIMs) or screws, on a flat surface adapted to receive the PBA on a non-flat heatsink. The heatsink may therefore have the desired 3D shape, which may be obtained by molding, punching (cutting) or extrusion.

Such implementations may however prove rather costly and have constraints for example as regards the thermal performances of the LEDs: actually, without the use of specific TIM materials, the thermal interface between PCB and heatsink may be reduced. Moreover, the cost of the material and of the mounting of the PBA assembly on the heatsink, as well as the logistic costs for handling the various components (heatsink, TIMs, glues, screws, PCBs, LEDs, connectors, electronic components etc.) may adversely affect the final cost of the product .

Other implementations may counter the previously outlined drawbacks by employing, instead of a flat PCB fixed on a non-flat (3d) heatsink, a printed circuit board with a bendable metal core, as available from various manufacturers (DuPont, Taconic, Kronach, Al Technology or FELA) . Such implementations may envisage the arrangement of the electrical circuit (with all the related steps of design, formation of exposed conductors, coating and application of a solder resist, etc.) on a flat board of the IMS kind, provided with a dielectric layer on the whole surface of the initial sheet. It is then possible to mount the LEDs, the connectors and the other electronic components on the board, e.g. by using a standard SMT process and solder pastes, or electrically conductive adhesives for the connections. Then the PBA is bent, e.g. via a punching operation, so as to achieve the desired non-flat (3D) structure .

Such solutions may be used in the presence of low thermal dissipation levels and may involve various advantages (a separate heatsink may be omitted and the fixing of the PCB board on the heatsink is easier) as regards both the necessary materials and the soldering process, while moreover achieving a lower logistic effort thanks to the reduction of involved materials.

However, the 3D (non-flat) shape that can be obtained by bending is limited by the imposed voltage induced in the dielectric material on the basis of the curvature radiuses and angles. Moreover, the strain induced by the bending in the dielectric of the IMS structure, which covers the whole surface of the metal substrate, may drastically reduce the electrical isolation of the light radiation sources (e.g. LED radiation sources), especially when the conductive lines or tracks are near the areas of the metal material which undergo bending-induced strain.

Object and Summary

One or more embodiments aim at overcoming the previously outlined drawbacks.

According to one or more embodiments, said object is achieved thanks to a support structure for lighting devices having the features specifically set forth in the claims that follow.

One or more embodiments may also refer to a corresponding device as well as to a corresponding method .

The claims are an integral part of the technical teaching provided herein with reference to the embodiments .

One or more embodiments may employ a substrate which acts as a heatsink, adapted to distribute heat and to lower the temperature of the light radiation source ( s ) .

One or more embodiments may employ a substrate acting as an effective heatsink and having a low cost, which may be used in the place of a heatsink made for example of molded aluminium.

Moreover, there is the possibility of having a substrate of a laminar metal sheet, to which it is possible to couple a light radiation source such as a LED module.

In one or more embodiments, this result may be achieved by designing a LED lighting module on a base of non-flat (3D) isolated aluminium without having to use an additional PCB board, and while avoiding traditional aspects typical of LED modules, LED lamps and LED lighting devices.

In one or more embodiments, a heatsink made of a bent metal sheet member may join:

functional aspects such as for example the distribution of the point-shaped thermal load, the continuous heat transfer towards a housing thanks to a large surface and a good internal conductivity, and/or through ventilation (always thanks to a large surface) , - an aesthetically pleasing aspect of the visible parts, obtained for example by bending a metal sheet so as to form a non-flat geometry.

One or more embodiments may be based on the idea of arranging the power supply circuit of the light radiation sources, including the dielectric layer, in positions of the substrate (e.g. of a metal material such as aluminium) located within portions of that substrate which are exempt from bending-induced strain.

In the present description and in the claims that follow, such portions exempt from bending-induced strain are meant to include portions of the substrate wherein such strain, although virtually present, is of a negligible amount. As a consequence, in one or several embodiments, said electrical circuit may be located, at least marginally, also in portions of the substrate which have been subjected to bending, while leaving a residual induced strain of a negligible amount .

One or several embodiments may employ, in order to implement said electrical circuit, thick-film processes which may be performed on metal substrates (e.g. aluminium substrates) as available from various manufacturers such as ESL Electroscience, DuPont, Heraeus and FERRO.

In one or more embodiments, the electrical circuit may be located directly on the substrate (e.g. of a metal material such as aluminium) which acts as a heatsink, while avoiding damages of the dielectric material which may be attributed to bending strains.

In one or more embodiments a substrate may be given a number of possible 3D (non-flat) shapes which may be much higher than the number achievable with bendable IMS boards, while keeping the thermal insulation and thermal resistance features.

One or more embodiments may offer one or more of the following advantages:

- ease of achieving a non-flat (3D) shape of the metal substrate, so as to replace, cheaply and effectively, a moulded heatsink having an IMS structure acting as a mounting structure for LED modules,

- possibility to keep the electrical insulation even after bending the metal substrate,

- desired thermal resistance, achievable with a single element or part, with the possibility of varying the thickness of the dielectric and/or by using so called thermally conductive "vias",

- improved internal thermal conductivity and heat transmission towards the other structures of the mounting assembly,

- easier integration of the module structure, by integrating interfacing structures for the orientation and the fixation both for outer and for inner components ,

- simpler bending process,

- lower costs for the mounting process, and

lower logistic costs, thanks to the less extensive BOM. Brief Description of the Figures

One or more embodiments will now be described, by way of non-limiting example only, with reference to the enclosed Figures, wherein:

- Figure 1, comprising four portions denoted with a) , b) , c) and d) , shows a method according to one or more embodiments,

- Figure 2, also comprising four portions denoted with a) , b) , c) and d) , shows a method according to one or more embodiments,

Figures 3 and 4 show possible details of embodiments ,

Figures 5 to 7 show various possible applications of embodiments, and

- Figures 8 to 11, wherein Figure 9 is a section along line IX-IX of Figure 8, show further possible details of embodiments.

It will be appreciated that, for a better clarity of illustration, the parts visible in the Figures are not to be considered necessarily drawn to scale.

Detailed Description

In the following description, numerous specific details are given to provide a thorough understanding of one or more exemplary embodiments. The embodiments may be practiced without one or several specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the embodiments. Reference throughout this specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the possible appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments, so that for instance a feature exemplified with reference to a solution shown in one of the Figures may be applied to a solution shown in another Figure: as an example of such a possibility, we may refer to connector lOe of Figure 8 and to the possibility of its application to the solution exemplified in Figure 5.

The headings provided herein are for convenience only, and therefore do not interpret the scope or meaning of the embodiments.

Figures 1 and 2, each comprising four portions denoted by a) , b) , c) and d) , show two possible embodiments of a support structure wherein a bending operation of the substrate follows (Figure 1) or precedes (Figure 2) the provision of an electrical circuit on the same substrate.

Identical or functionally equivalent parts or elements appearing both in Figure 1 and in Figure 2 are denoted with the same references, without repeating the description thereof. It will moreover be appreciated that the various features exemplified with reference to the following Figures 3 to 11 are in general equally applicable to both embodiments of Figures 1 and 2.

Both embodiments exemplified in Figures 1 and 2 may envisage a laminar member of a flat metal material (e.g. an aluminium sheet) e.g. obtained by punching (cutting) .

In one or more embodiments, the laminar member 10 - see Figures la) and 2a) - is adapted to have e.g. a shape at least approximately resembling a star, with a central or web portion 10a from which radial extensions ("fingers") branch off.

The shape and distribution of extensions 10b exemplified in the presently considered Figures is however merely exemplary.

Indeed, extensions 10b may all have the same shape, or they may have different geometric features. For example, in one or more embodiments extensions 10b may either have all the same length, or else two or more different lengths.

In one or more embodiments, radial extensions 10b may be provided alternatively, wherein for example a "short" finger is interposed between two pairs of "long" fingers.

In one or more embodiments, radial extensions 10b may have either a regular or an irregular angular distribution .

Moreover, the angular distribution of extensions 10a may be irregular, e.g. with separation angles between neighbouring extensions 10b varying along the periphery of member 10.

In the embodiment exemplified in the Figures, extensions 10b may be bent with regard to the central part or web 10a, so as to give member 10 a general cup^¬ like (or "tulip") shape, visible for instance in Figure Id) or in Figures 2b, 2c) and 2d) .

The possible different lengths of extensions 10b may cause the presence, in the array of radial extensions surrounding the central part 10a, of gaps or notches in the positions corresponding to the shorter radial extensions 10b. In one or more embodiments, this is achieved while keeping the separation between neighbouring extensions irrespective of their length.

In one or more embodiments, as exemplified in the Figures, radial extensions 10b may have distal portions 10c that are at least slightly bent outwards, through a bending operation which may be carried out before, after and/or during the bending operation of radial extensions 10b with respect to the central portion or web 10a.

In one or more embodiments, laminar member 10 may be made of aluminium or whatever material which may be cut with a shape as shown, e.g. through punching or cutting, and be then subjected to bending.

Such materials may have a controlled roughness and may be made of a material, aluminium, which is capable of being bent.

In one or more embodiments, as exemplified in Figure lb) , when member 10 is still in a flat shape, it is possible to form an electrical circuit 12 thereon, on which it is possible to mount electrically powered light radiation sources such as LEDs .

In one or more embodiments, electrical circuit 12 may include pads 12a for mounting light radiation sources L, and lines 12b for the connection of pads to terminals 12c, for the possible connection to an electronic drive circuit (see for example reference 40 in Figures 5 to 7) .

In one or more embodiments, electrical circuit 12 may comprise:

- a dielectric layer (see reference 120 in Figures

3 and 4) which is destined to ensure the electrical insulation towards substrate 10, if the latter is made of an electrically conductive material, such as a metal like aluminium,

- electrically conductive pads/lines/terminals

12a, 12b, 12c, and optionally

a solder mask for the connection with light radiation sources (e.g. LEDs L) .

In one or more embodiments, such an electrical circuit 12 may be implemented directly on substrate 10 by using a thick-film process.

In one or more embodiments it is possible to use thick-film processes with ceramic- or glass-based pastes (for example with firing temperatures higher than 510°C), polyimide-based pastes (with reticulation temperatures between 200°C and 350°C) or epoxy-based pastes (with a reticulation temperature of about 150°C) .

The reference to such technological options, and to the corresponding parameters, is obviously merely exemplary and non-limiting of the embodiments.

In one or more embodiments it is possible to resort to thick-film processes with lower firing or reticulation temperatures, taking into account the possibility of using thin laminar materials for the bendable substrate 10, for example aluminium sheets with thicknesses up to 0,5 mm. The use of thin substrates offers the possibility of obtaining the desired shape (web part 10a and extensions 10b) via a punching or cutting process, achieving a structure which can be bent easily.

After the provision of the electrical circuit (Figure lb) the light radiation sources L may be mounted on pads 12a as exemplified in Figure lc) , while lines 12b ensure the power supply to terminals 12c and, optionally, the connection to electronic drive circuits of the LEDs, e.g. in order to achieve a thermal control thereof .

In one or more embodiments, the mounting of the LEDs (and possibly of other electronic components) on circuit 12 may take place through a standard SMT process, with a solder paste or an adhesive.

Subsequently, as schematically shown in Figure Id) , the initial laminar member 10 may be bent so as to give it a non-flat (3D) shape. It may be for example an inverted cup shape, as shown in Figure Id, the web part 10a accommodating the electrical circuit 12 (on which LEDs L are mounted) and the extensions 10b surrounding the face of web 10a opposed to the face mounting the LEDs.

One or more embodiments, as exemplified in Figure 1, may have the advantage of permitting a simple structure of electrical circuit 12, also as regards the mounting of components such as LEDs L, while optionally working on large flat panels.

One or more embodiments as exemplified in Figure 1 may in some cases suffer from limitations as regards the area of web portion 10a which is available for circuit 12, if one wishes to avoid the use of the connection areas between web part 10a and extensions 10b which are subjected to strain during the bending operation .

What has been previously stated with reference to the embodiments exemplified in Figure 1, e.g. as regards the possibility of using a flat bendable metal such as aluminium, formed e.g. by punching, and as regards the thickness and the film processes which can often be used to form circuit 12, can be applied in the same way to the embodiments exemplified in Figure 2.

In this case the bending operation of substrate 10

(exemplified in Figure 2b) , which gives substrate 10a, 10b the non-flat/3D shape, precedes (instead of following) the formation of electrical circuit 12 (Figure 2c) and the application of the light radiation sources (Figure 2d) .

Embodiments as exemplified in Figure 2 may require the use of supporting tools, which are adapted to hold substrate 10 once it has been bent into the non-flat shape (e.g., the shape of an inverted cup), both during the formation of electrical circuit 12 and during the application of LEDs L or other components onto the circuit itself.

One or more embodiments as exemplified in Figure 2 may enable the provision of electrical circuit 12 on an area of web portion 10a which is larger than in embodiments as exemplified in Figure 1.

In one or more embodiments as exemplified in Figure 2, electrical circuit 12 may be located (also) in positions within the portions of substrate 10 which undergo bending (for example the peripheral portions of web part 10a which connect to extensions 10b) , because in such positions the residual bending-induced strain is negligible, so that they may actually be considered exempt from such induced strain.

Moreover, it will be appreciated that Figures 1 and 2 are not exhaustive of the possible variations of one or more embodiments.

As a non-limiting example, in one or more embodiments circuit 12 may be formed on a flat substrate 10 before this is subjected to punching or cutting, in order to obtain member 10 exemplified in Figure la. Actually, it is possible to obtain a plurality of circuits 12 on a flat sheet (e.g. of a metal material as aluminium) and only then to cut out single members 10 as shown in Figure la on which, before cutting out the single member, circuit 12 has been formed (with the application of the LEDs L and of other components, which may as well optionally precede the cutting out of the single member 10) .

In the same way, always referring as an example to

Figure 1, the mounting operation of LEDs L or other components on circuit 12, which is formed on the flat member 10, may be performed after substrate 10 has been bent into the non-flat (3D) shape, in a similar way to what takes place in the embodiments exemplified in Figure 2.

One or more embodiments may achieve optimal features as regards the BOM and the cost of performing the bending process, e.g. by resorting to thin substrates 10 and/or by reducing the area subjected to bending-induced strain.

In one or more embodiments, the reduction of the thickness of layer 10 may cause an increase of thermal resistance in the module as a whole. This effect may be compensated for example by reducing the dielectric thickness, while bearing in mind that the latter does no longer have to resist strain, which allows for the use of thinner dielectrics (e.g. through a thick-film process) .

Figures 3 and 4 show in an enlarged scale a portion of circuit 12, wherein reference 120 denotes a dielectric layer (for example an epoxy-based or a polyimide-based dielectric) which may achieve the electrical insulation towards a substrate 10 of metal material, both for pads 12a for the mounting of LEDs (not visible in Figures 3 and 4) and for conductive lines 12b.

In one or more embodiments, the electrically conductive part of circuit 12 may be made of silver or a silver-based material.

In both Figures 3 and 4, reference 120a exemplifies a pad having a heatsink function, which may be achieved for example via a silver-based metal material, having the function of dissipating the heat generated by the overlying LED during the operation thereof .

Specifically, Figure 4 exemplifies the possibility of implementing, at pad 120a, a so-called path or "via" 120b of a thermally (and electrically) conductive material, such as a silver-based material, so as to promote heat dissipation from the LED towards substrate 10.

In one or more embodiments, pad 120a and via 120b may also be formed through thick-film technology.

The general inverted-cup shape shown in Figures 1 and 2 is merely exemplary, and must not be considered limitative of the embodiments.

In one or more embodiments, extensions 10b may be oriented in any direction from web portion 10a, so as to achieve a cooling effect, for example through simple air ventilation.

For example, in one or more embodiments, extensions 10b, which are presently shown as directed outwards from web part 10a, may at least marginally extend towards the interior of a web part 10a having generally a ring shape.

In one or more embodiments, the profile of extensions 10b and/or their bending shape may be chosen on the basis of the mounting requirements of lighting device (substrate 10a, 10b, electrical circuit 12, LEDs L and other circuits mounted thereon) within a housing.

For example, the lighting device according to one or more embodiments may be mounted within the truncated-cone-shaped body 30 of a housing which (according to a solution currently adopted for LED lighting devices) reproduces on the whole the appearance of a light bulb.

In one or more embodiments, a lighting device as previously exemplified may be arranged at the distal end of body 30 (i.e. the end which will be covered by a transparent bulb cap, not visible in the Figures), the extensions 10b being adapted to hold, within body 30, substrate 10 with circuit 12 and radiation sources L mounted on the web portion 10a. The body portion 30 between web part 10a and the proximal end of body 30 itself (which is destined to be turned towards the screw base of the bulb lamp) may therefore accommodate an electronic drive circuit 40 of light sources L.

As exemplified in Figures 5 to 7 (wherein circuit 12 and radiation sources L are schematically shown with dashed lines), the connection of lighting device to body 30 may be achieved in various different ways.

For example, extensions 10b may be adapted to snap-fit engaging an inner radial edge of body 30.

Moreover, Figure 5 exemplifies one or more embodiments wherein extensions 10b of a support structure having a general cup-like shape extend in the neighbourhood of the peripheral wall of body 30, and are connected to the latter via an adhesive material 32. In one or more embodiments, it may be a thermally conductive adhesive material, so as to promote heat dissipation towards body 30 of the lamp housing.

Figures 6 and 7 exemplify, according to the same modes of Figure 5, the possibility of mounting the lighting device in the body 30 by using a mass of potting material 34 (of a kind known in itself, e.g. of a polyurethane material) adapted to occupy the internal volume included by extensions 10b which surround the web part 10a, either completely (Figure 6) or only partially, for example by leaving a portion near the web part 10a free (Figure 7) .

In one or more embodiments, as exemplified in Figures 6 and 7, potting mass 34 may also extend into the space included by extensions 10b and the wall of body 30, so as to perform an anchoring function, for example through snap-fitting, through an adhesive material 32 as exemplified in Figure 5, or through insert moulding. In one or more embodiments, it is also possible to use in combination the various solutions exemplified herein, e.g. with an adhesive material 32 on the outside of extensions 10b (i.e. between extensions 10b and the wall of body 30) and a potting mass 34 in the internal volume surrounded by extensions 10b.

In one or more embodiments as exemplified in Figures 5 to 7, the internal volume included by the extensions 10b which surround the web part 10a on the face opposite the face whereon the LEDs L are mounted is adapted to accommodate drive circuit 40.

As schematically exemplified in Figure 5, in one or more embodiments circuit 40 may be retained in position through flaps or noses lOd extending from support structure 10a, 10b. In one or more embodiments, they may be flaps or noses provided with an end notch or slot (as exemplified also in Figures 1 and 2) so as to form a sort of fork adapted to enclose circuit board 40, while keeping it in position.

As schematically exemplified in Figures 6 and 7, in one or more embodiments circuit 40 may be held in position thanks to its being embedded in the potting mass 34.

Figure 8 exemplifies the fact that extensions 10b, which are subjected to bending in order to give the support structure a non-flat (3D) shape, are adapted to the mounting for example of a light radiation source L in a central position with respect to central portion 10a with an electrical circuit. There is moreover the possibility that this portion may form the upper (or base) part of a mounting volume or chamber for source L and, possibly, of an associated optics such as for example a TIR (Total Internal Reflection) lens.

In one or more embodiments it is therefore possible to have a direct heat distribution towards the surrounding air, e.g. in the case of mounting in a ceiling W as a spotlight or a downlight.

One or more embodiments as exemplified in Figure 8 may offer the possibility to integrate an electrical connector lOe into structure 10a, 10b.

Figure 9 (corresponding to a section according to line IX-IX of Figure 8) exemplifies the fact that, in one or more embodiments, extensions 10b may be bent, i.e. twisted or turned, so as to lie in diametrical planes passing through a central axis X10A normal to web part 10a.

Figure 10 exemplifies (according to a viewpoint similar to Figure 9) the fact that, in one or more embodiments, the action of twisting/ turning extensions 10b may only be partial, so that the extensions 10b may lie on slanted planes with respect to central axis X10A.

Figure 11 exemplifies (once again according to a viewpoint similar to Figure 9) embodiments wherein structure 10a, 10b takes on a shape as exemplified in Figures Id) and 2d), i.e. with the extensions 10b being bent but not twisted, so that extensions 10b come to lie along an ideal surface shaped as a cylinder or as a truncated cone, centred about axis X10A.

Figures 9 to 11 exemplify the possibility to influence, in one or more embodiments, the orientation of extensions 10b with respect to axis X10A to enhance, with the purpose of dissipating heat, the action of radial diffusion (e.g. through radiation) and/or the convection effect on the surface of extensions 10b.

Embodiments as exemplified in Figures 8 to 11 may be used, for example, in order to achieve an air cooling action of the light radiation source (s) L, which are shown here with an associated reflector R. Embodiments of this kind may be used, for example, for integrated recessed lighting devices and/or for devices wherein extensions 10b are left in view, achieving a pleasant aesthetic effect.

Moreover, a connector lOe as shown in Figure 8 may be present in one or more embodiments as exemplified in Figure 5, e.g. by using one of the extensions carrying slotted noses lOd in order to achieve a contact towards circuit 40.

In one or more embodiments there is the possibility to optimize, while reducing scraps, the use of the starting material used to make support structure 10a, 10b, by starting from an approximately rectangular sheet of laminar material. Through a punching or cutting operation it is possible to form radial extensions 10b around a web portion 10a, separating the single extensions through simple straight dividing lines (as against the segment cuts separating extensions 10b in Figures la and 2a) . In one or more embodiments, thanks to the general plastic deformability of the starting material (e.g. aluminium sheet) , this way of cutting extensions does not affect the possibility of reaching for example the final shape of a cup, as shown for instance in Figures Id) and 2d) .

In one or more embodiments, the separating spaces between neighbouring extensions 10b may allow to set apart extensions 10b (even when they are already forming a cup shape with respect to the web portion 10a) in order to insert therein an electronic circuit such as circuit 40, visible in Figures 5 to 7. Irrespective of the chosen mounting solution, in one or more embodiments extensions 10b may actually be adapted to be set apart in order to enable the insertion of circuit 40 into the volume which they comprise, even when the circuit is "larger" than the opening defined by the distal ends of extensions 10b. It is moreover possible to arrange circuit 40 in the internal space defined by extensions 10b (e.g. via slotted noses lOd) and to hide it from the outside.

In one or more embodiments, circuit 40 may comprise for example a Printed Circuit Board (PCB) adapted to be firmly supported by extensions 10b even when circuit 40 is simply inserted within body 30, as exemplified in Figure 5, i.e. even without using the potting mass 34 of Figures 6 and 7.

In one or more embodiments, the surface of extensions 10b may be provided with structures of the IMS type, and/or connecting lines of circuit 40, for the purpose of a connection to LEDs L. There is moreover provided the possibility of implementing the ends of such elements as connectors, while avoiding separate plug connection elements.

In one or more embodiments, the very surface of extensions 10b may be used as a board to hold components, e.g. components of drive circuit 40.

In one or more embodiments, the inherent elasticity allows for a spring contact function.

One or more embodiments therefore lead to the implementation of electronic modules with high thermal performances, the electronic components being arranged on a substrate acting as a heatsink of a non-flat 3D shape. Such a substrate is adapted to be made e.g. of a laminar metal material such as aluminium, being therefore cheaper than moulded heatsinks and achieving at the same time a better heat transfer than can be obtained by using separate boards of the PCB kind, thermal interface materials (TIM) and/or heatsinks made of different parts.

In one or more embodiments, electrical circuit 12 may be obtained by moulding, possibly before bending substrate 10, with simplified mounting operations and with the possibility of using (e.g. in embodiments as exemplified in Figure 2) also substrate portions that are involved in the bending process.

In one or more embodiments, the intervention on heatsinks that are already bent in a non-flat surface, although requiring the use of specific supports, may lead to an improved efficiency of the mounting process thanks to the simplification of the overall process.

In embodiments which envisage potting masses (see for example Figures 6 and 7) it is possible to reduce the required mounting space for the injection needle, while the operation of injection of the potting mass may be executed in one single step instead of two, e.g. by introducing the potting mass 34 from below, as exemplified in Figure 7. In this Figure, reference 340 denotes a potting tool which is adapted to receive the proximal part (corresponding to the screw base) of body 30, in sealing conditions thanks to the presence of gaskets (e.g. o-rings) 342, so as to allow the injection of the potting mask from an injection channel 344.

The existing separation spaces between the extensions 10b allow for an easy evacuation of air during the injection of the potting mass.

In the embodiments that comprise the use of adhesive materials (see for example Figure 5), the adhesive material may be applied by immerging the substrate into a liquid, more or less viscous adhesive, so as to wet extensions 10b. This also ensures the advantage that, once substrate 10a, 10b has been inserted into body 30, the adhesive material applied on extensions 10b may flow towards the lower portion of body 30 so as to achieve simultaneously the fixing of electronic circuit 40 within body 30. In one or more embodiments, star shapes as exemplified in Figures la and 2a may be obtained with techniques different from punching, e.g. through laser cutting or water-jet cutting.

The bending operation (see for example the sequence of Figures lc and Id or the sequence of Figures 2a and 2b) may be performed in a single step or in subsequent steps, possibly by overlaying a bending operation and a twisting operation, e.g. when extensions 10b must be given an arrangement on radial or slanted planes with respect to axis XlOa, exemplified in Figures 9 and 10.

Of course, without prejudice to the basic principles, the details and the embodiments may vary, even appreciably, with respect to what has been described herein by way of non-limiting example only, without departing from the extent of protection. The extent of protection is defined by the annexed claims.

Claims

1. A support structure for lighting devices, including :

- a non-flat substrate (10a, 10b) including a flat laminar member (10) subjected to bending, and

- an electrical power supply circuit (12) on said substrate,

wherein :

- the non-flat substrate (10a, 10b) includes first portions exhibiting bending-induced strain and second portions exempt from bending-induced strain, and

- said electrical power supply circuit (12) is at locations of said non-flat substrate (10a, 10b) included in said second portions.

2. The support structure of claim 1, wherein said non-flat substrate (10a, 10b) includes a metal material, preferably aluminium.

3 . The support structure of claim 1 or claim 2, wherein said electrical power supply circuit (12), preferably including an electrically insulating layer (120), is formed as a thick-film layer on said substrate .

4. The support structure of any of the previous claims, wherein said non-flat substrate (10a, 10b) is a cup-shaped substrate including:

- a flat web portion (10a) with said electrical power supply circuit (12), and

- a plurality of radial extensions (10b) bent to surround said flat web portion (10a) .

5. The support structure of any of claims 1 to 4, wherein said flat laminar member (10) subjected to bending is a laminar member formed by any of punching, laser cutting or water beam cutting.

6. A lighting device, including:

- a support structure according to any of claims 1 to 5 having a plurality of bent extensions (10b), at least one electrically powered light radiation source (L) coupled with said electrical power supply circuit (12) of said support structure, and

- a containment housing (30) for said support structure (10a, 10b, 12) with said bent extensions (10b) retaining the support structure within said housing (30) .

7. The device of claim 6, including:

- said non-flat substrate (10a, 10b) being cup- shaped with an inner space surrounded by said bent extensions (10b), and

- a drive circuit (40) for said at least one light radiation source (L) arranged in said inner space.

8. The device of claim 7, including bent extensions (lOd) which support said drive circuit (40) in said inner space.

9. The device of any of claims 6 to 8, including bent extensions (10b) glued (32), preferably with a thermally conductive adhesive, to said housing (30) .

10. The device of any of claims 6 to 9, including a mass of a potting material (34) in said support structure (10a, 10b) contained in said housing (30) .

11. A method of providing a support structure for lighting devices according to any of claim 1 to 5, the method including:

- providing a flat laminar member (10) of a material bendable for forming said non-flat substrate (10a, 10b) , and

- a) bending said flat laminar member (10) to form said non-flat substrate (10a, 10b) including first portions exhibiting bending-induced strain and second portions exempt from bending-induced strain, by forming said electrical power supply circuit (12) at positions of said non-flat substrate (10a, 10b) included in said second portions,

or

- b) forming said electrical power supply circuit (12) on said flat laminar member (10) and bending said flat laminar member (10) having said electrical power supply circuit (12) formed thereon to form said non- flat substrate (10a, 10b) including first portions exhibiting bending-induced strain and second portions exempt from bending-induced strain, with said electrical power supply circuit (12) at locations of said non-flat substrate (10a, 10b) included in said second portions.