Light generating system and method for manufacturing the same

Abstract

An arrangement (1) comprising an electrical arrangement (4), a housing (3), and a potting material (2), the housing (3) comprising an inner surface (31) oriented to provide an inner cavity (30), the inner cavity (30) enclosing the electrical arrangement (4) and the potting material (2), the electrical arrangement (4) comprising a top surface (41) having a three-dimensional topology created by one or more electrical components (42) comprised by the electrical arrangement (4), the potting material (2) being thermally conductive, electrically insulating, and comprising a cross-linked polymer (20). The potting material (2) is arranged on at least a part of the top surface (41) of the electrical arrangement (4) such that it follows the contours of the three-dimensional topology of the top surface (41). The potting material (2) is in thermal contact with the one or more electrical components (42). The potting material is a brittle material. The cross-linked polymer (20) comprises a cross-link density of at least 0.0005 mol / cm3.

Description

[0001] LIGHT GENERATING SYSTEM AND METHOD FOR MANUFACTURING THE SAME

[0002] FIELD OF THE INVENTION

[0003] The invention relates to an arrangement comprising an electrical arrangement, a housing, and a potting material. The invention further relates to a light generating system comprising a light generating device and such an arrangement. The invention further relates to a method for encapsulating or potting an electrical arrangement and to an electrical arrangement encapsulated or potted using such a method. The invention still further relates to a method for separating from the potting material an electrical arrangement encapsulated or potted using a method for encapsulating or potting an electrical arrangement.

[0004] Generally, a monomer is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.

[0005] As used herein, functionality is intended to refer to the presence of functional groups in a molecule. A monofunctional molecule possesses one functional group, a difunctional two, a trifunctional three, and so forth. In relation to monomers, functionality is intended to refer to the monomer’s number of polymerizable groups and affects the formation and the degree of crosslinking of polymers. The functionality of a monomer may be defined as the number of bonds that a monomer's repeating unit forms in a polymer with other monomers.

[0006] As used herein, a link is intended to refer to one or more groups of atoms linking functional groups of a molecule.

[0007] As used herein, a cross-link is intended to refer to chains or segments that connect two infinite parts of a polymer network.

[0008] The cross-link density of a polymer is defined as the number of cross-links per unit volume in a polymer network, normally stated by the unit mol / cm3. The cross-link density can be determined by several different methods. For instance, one may use ASTM standard number D2765 as a method guideline. This method determines the gel content and swell ratio for a known mass of polymer extracted in an appropriate solvent at a specific temperature for a specific amount of time. Another feasible method is to use rheological tests. As used herein, the term “room temperature”, denoted TR, is intended to refer to a temperature of 25 degrees Celsius.

[0009] BACKGROUND OF THE INVENTION

[0010] For outdoor applications potting materials are used for encapsulating or potting electrical components such as to protect the electrical components as well as providing good thermal connection between the components which, during use, become hot and produce hotspots.

[0011] For instance, US 2007 / 0142528 Al discloses providing a curable resin composition which is curable at room temperature TR, has fluidity, is excellent in workability and provides a cured product having high thermal conductivity and being excellent in flexibility as a potting material. US 2007 / 0142528 Al suggests a curable resin composition comprising a (meth)acrylate monomer, an organic peroxide, a decomposition accelerator for the organic peroxide, and an inorganic filler, wherein the inorganic filler has a predetermined particle size distribution and serves to improve the thermal conductivity of the potting material. The resin composition is cure by air-curing using a drying oil.

[0012] Circularity and sustainability are currently at the top of the agenda of almost all companies not only to present themselves as green companies but also due to legislations which force them to make recycling of their products possible.

[0013] However, currently used potting materials get stuck within the components and it becomes impossible to separate them from the potting material. Therefore, recycling of current potted electronics components is not readily possible.

[0014] SUMMARY OF THE INVENTION

[0015] It is an object of the present invention to overcome this problem, and to provide an arrangement comprising an electrical arrangement, a housing, and a potting material as well as a method for encapsulating or potting an electrical arrangement, which enables the provision of a potting material which properly encapsulates or pots the electrical arrangement, but at the same time does not get stuck, or only to a limited degree get stuck, within the electrical arrangement, and with which it becomes possible to easily separate the electrical arrangement from the potting material such as to readily allow recycling.

[0016] According to a first aspect of the invention, this and other objects are achieved by means of an arrangement comprising an electrical arrangement, a housing, and a potting material, where the housing comprises an inner surface oriented to provide an inner cavity, where the inner cavity is enclosing the electrical arrangement and the potting material, where the electrical arrangement comprises a top surface having a three-dimensional topology created by one or more electrical components comprised by the electrical arrangement, where the potting material is thermally conductive, electrically insulating, and where the potting material comprises a cross-linked polymer, where the potting material is arranged on at least a part of the top surface of the electrical arrangement such that it follows the contours of the three-dimensional topology of the top surface, where the potting material is in thermal contact with the one or more electrical components, and where the potting material is a brittle material.

[0017] Thereby, and especially by providing that the potting material is in thermal contact with the one or more electrical components, and that the potting material is a brittle material, an arrangement is provided which comprises a potting material which properly encapsulates or pots the electrical arrangement, but at the same time does not get stuck, or only to a limited degree get stuck, within the electrical arrangement.

[0018] Further, especially by providing that the potting material is a brittle material, an arrangement is provided which comprises a potting material with which it becomes possible to easily separate the electrical arrangement from the potting material such as to readily allow recycling.

[0019] The arrangement may form part of a light generating system comprising a light generating device, where the light generating device comprises a solid state light source, where the arrangement is functionally coupled to the light generating device, and where the arrangement may be configured as a driver or a controller for the light generating device.

[0020] The cross-linked polymer may comprise a cross-link density of at least 0.0005 mol / cm3, or at least 0.001 mol / cm3, or at least 0.008 mol / cm3, or even at least 0.010 mol / cm3.

[0021] Thereby, an arrangement is provided which comprises a potting material which properly encapsulates or pots the electrical arrangement, but at the same time does not get stuck, or only to a limited degree get stuck, within the electrical arrangement.

[0022] Further, an arrangement is provided which comprises a potting material with which it becomes possible to easily separate the electrical arrangement from the potting material such as to readily allow recycling.

[0023] The degree of reaction of reactive groups forming the cross-linked polymer may be at least 70 %, at least 75 %, at least 80 %, at least 85 % or at least 90 %. Thereby, an arrangement is provided which comprises a potting material with which it becomes possible to separate the electrical arrangement even more easily from the potting material such as to readily allow recycling.

[0024] The cross-linked polymer may exhibit a strain at break being less than 4% Thereby, an arrangement is provided which comprises a potting material with a sufficiently low strain at break to allow particularly easy separation of the electrical arrangement from the potting material such as to readily allow recycling.

[0025] The brittleness of the cross-linked polymer may be higher than l*10'8(%Pa)-1. One way of describing the brittleness, B is by the equation B =l / (sbE’), where 8b is the tensile strain at break (in %) and E’ is the storage modulus as determined by dynamic mechanical analysis (DMA). Thereby, an arrangement is provided which comprises a potting material with a sufficiently high brittleness to allow particularly easy separation of the electrical arrangement from the potting material, for instance by subjecting the arrangement to a mechanical shock, such as to readily allow recycling.

[0026] The cross-linked polymer may comprise a loss modulus being less than 1 GPa at room temperature TR.

[0027] Thereby, an arrangement is provided which comprises a potting material with a sufficiently low loss modulus to allow particularly easy separation of the electrical arrangement from the potting material such as to readily allow recycling.

[0028] The cross-linked polymer may comprise a notched Izod impact strength at room temperature TR being less than 1 kJ / m2, or less than 0.5 kJ / m2.

[0029] The notched Izod impact strength may be determined by the test described in the ASTM International standard no. ASTM D256 also known as “Notched Izod Impact Strength.” The test determines if a material complies with certain impact requirements or to determine the toughness of the material. The toughness of a material is a factor of its ability to absorb energy during plastic deformation. Brittle materials, for example, have low toughness as a result of the minimal amount of deformation they can endure. Impact toughness of a given material can also be impacted by temperature changes - in general, impact toughness decreases the lower the temperature gets. The Notched Izod Impact test is a single point test that measures a materials resistance to impact from a swinging pendulum. Izod impact is defined as the kinetic energy needed to initiate fracture and continue the fracture until the specimen is broken. The test specimen used in the Notched Izod Impact test are notched to prevent deformation of the specimen upon impact. Thereby, an arrangement is provided which comprises a potting material with a sufficiently low impact strength at room temperature TR to allow particularly easy separation of the electrical arrangement from the potting material such as to readily allow recycling.

[0030] In embodiments, the cross-linked polymer may comprise a notched Izod impact strength at room temperature TR being at least 0.05 kJ / m2or at least 0.1 kJ / m2. The obtained effect is improved reliability of the arrangement i.e. the driver or the controller. The reason is that the cross-linked polymer is not too brittle. If the cross-linked polymer is too brittle and thus too prone to cracking and breaking when slightly impacted e.g. falling on / punching to a surface e.g. a table or ceiling.

[0031] The cross-linked polymer may comprise a loss tangent peak at a temperature T which is above 80 degrees Celsius.

[0032] Thereby, an arrangement is provided which comprises a potting material with a loss tangent peak appearing at a sufficiently high temperature to allow particularly easy separation of the electrical arrangement from the potting material such as to readily allow recycling.

[0033] In embodiments, the housing may be resilient, or the housing may comprise a housing layer being resilient. The housing layer may be a coating applied on the inner surface or outer surface of the housing. The housing or the housing layer may be (made of) a rubber or (flexible) foam material. The housing or housing layer may be flexible. The housing or housing layer may be soft. The housing may have a housing wall having a thickness of at least 3 mm. The obtained effect is improved reliability of the arrangement i.e. the driver or the controller. The reason is that the brittle potting material is protected by a resilient / soft / flexible part / material such that when the arrangement is slightly impacted e.g. falling on / punching to a surface e.g. a table or ceiling, the brittle polymer does not crack. It may only crack when the potting material is impacted directly.

[0034] The minimum distance, defined by the length of the cross-links Dx between main polymer chains of the cross-linked polymer, may be less than or equal to 30 angstrom (A), less than or or equal to 40 A, less than or or equal to 30 A, or less than or or equal to 25 A.

[0035] By providing the potting material with such a cross-linked polymer, it becomes possible to separate the electrical arrangement even more easily from the potting material such as to readily allow recycling. The cross-linked polymer may be a brittle cross-linked polymer being a rigid, inflexible material that is prone to cracking and breaking when impacted.

[0036] Thereby, an arrangement is provided which comprises a potting material with which it becomes possible to separate the electrical arrangement even more easily from the potting material such as to readily allow recycling.

[0037] The potting material is a monomer with multiple functional groups, and the potting material may be a monomer chosen from the group comprising Epoxy-systems, multifunctional acrylates, urethane systems, thiolene systems and siloxanes.

[0038] Such potting materials have been proven experimentally by the inventors to be particularly suitable for obtaining one or more of the above features related to the crosslinked polymer of the potting material upon polymerization of such a monomer.

[0039] The cross-linked polymer may be obtained by thermally induced polymerization of the potting material at a polymerization initiation temperature, TP, of at least 30, at least 60 or at least 120 degrees Celsius followed by cooling to room temperature, TR.

[0040] The polymerization initiation temperature, TP, of at least 30, at least 60 or at least 120 degrees Celsius may be maintained for at least 30 minutes, at least 60 minutes or at least 120 minutes.

[0041] Alternatively, the cross-linked polymer may be obtained by thermally induced polymerization of the potting material at a polymerization initiation temperature, TP, of at least 30, at least 60 or at least 120 degrees Celsius followed thermally induced polymerization at an elevated temperature, TE, compared to the polymerization initiation temperature, TP, followed by cooling to room temperature, TR.

[0042] The polymerization initiation temperature, TP, may be maintained for at least 5 minutes, at least 10 minutes or at least 30 minutes, and the elevated temperature, TE, may be maintained for between at least 10 minutes, at least 20 minutes or at least 30 minutes.

[0043] Such a polymerization have been proven experimentally by the inventors to be particularly suitable for obtaining a cross-linked polymer comprising one or more of the above features.

[0044] The cross-linked polymer may comprise a particulate filling material, wherein the particulate filling material comprises a thermally conductive material having a thermal conductivity of at least IW / mK. The obtained effect is improved separability of the electrical arrangement from the potting material because it increase the brittleness of the potting material, while also improved the thermal management e.g. reliability of the electrical components.

[0045] The particles of the particulate filling material may have an average particle size in a range from 0.1 mm to 1 mm (or 0.2 mm to 0.8 mm). The obtained effect is improved separability of the electrical arrangement from the potting material. The reason is that the electrical components used in drivers or controller have dimensions being a bit larger than a few millimeters e.g. in a range from 3 to 10 mm.

[0046] The concentration of the particulate filling material may have a gradient over the potting material, wherein the highest concentration of particulate filling material close to the one or more electrical components. The obtained effect is improved reliability and separability. The reason is that the potting material easily separates from the electrical components but is less brittle at locations more remote from the components providing protect against situations of unwanted cracking.

[0047] The cross-link density may have a gradient over the potting material, wherein the highest cross-link density is close to the one or more electrical components. The obtained effect is improved reliability and separability. The reason is that the potting material easily separates from the electrical components but is less brittle at locations more remote from the components providing protect against situations of unwanted cracking.

[0048] The invention further relates to a light generating system comprising (i) a light generating device and (ii) an arrangement according to the invention, wherein the light generating device comprises a solid state light source, wherein the arrangement is functionally coupled to the light generating device, and wherein the arrangement is configured as a driver or a controller for the light generating device.

[0049] The invention further relates to a method for manufacturing an arrangement, such as an arrangement of a light generating system according to the invention, the arrangement comprising an electrical arrangement, a housing, and a potting material, the housing comprising an inner surface oriented to provide an inner cavity, the inner cavity enclosing the electrical arrangement and the potting material, and the electrical arrangement comprising a top surface having a three-dimensional topology created by one or more electrical components comprised by the electrical arrangement, wherein the method comprises:

[0050] - providing the potting material in the form of a thermally conductive, electrically insulating potting material comprising a cross-linkable monomer, - depositing the cross-linkable monomer into the housing by arranging the potting material on at least a part of the top surface of the electrical arrangement such that it follows the contours of the three-dimensional topology of the top surface, and such that it is in thermal contact with the one or more electrical components, and

[0051] - where the method further comprises, after encapsulating or potting the electrical arrangement and the housing, polymerizing the potting material such as to form a cross-linked polymer, where the potting material with the thus formed cross-linked polymer is a brittle material.

[0052] The cross-linked network thus formed may comprise a cross-link density of at least 0.0005 mol / cm3.

[0053] The manufacturing method may further comprise introducing a filler material into the cross-linked network of the polymerized potting material, the filler material being configured to improve the thermal conductivity of the potting material. The filler material may be sand, glass or aluminum oxide particles.

[0054] The manufacturing method may further comprise adding to the potting material an additive configured to increase the capability of the monomer to absorb water.

[0055] The step of polymerizing the potting material may further comprise thermally inducing the polymerization of the potting material at a polymerization initiation temperature, TP, of at least 30, at least 60 or at least 120 degrees Celsius followed by cooling to room temperature, TR.

[0056] The polymerization initiation temperature, TP, of at least 30, at least 60 or at least 120 degrees Celsius may be maintained for at least 30 minutes, at least 60 minutes or at least 120 minutes.

[0057] Alternatively, the step of polymerizing the potting material may further comprise thermally inducing the polymerization of the potting material at a polymerization initiation temperature, TP, of at least 30, at least 60 or at least 120 degrees Celsius followed thermally induced polymerization at an elevated temperature, TE, compared to the polymerization initiation temperature, TP, followed by cooling to room temperature, TR.

[0058] The polymerization initiation temperature, TP, may be maintained for at least 5 minutes, at least 10 minutes or at least 30 minutes, and the elevated temperature, TE, may be maintained for between at least 10 minutes, at least 20 minutes or at least 30 minutes.

[0059] The invention further relates to a method for separating an electrical arrangement encapsulated or potted using a method according to the invention from a potting material, the method comprising bursting the potting material by applying a mechanical shock to the potting material.

[0060] The invention further relates to a method for separating an electrical arrangement encapsulated or potted using a method according to the invention from a potting material, the method comprising one or both of (i) bursting the potting material by applying a solvent to the potting material, and (ii) bursting the potting material by applying the solvent to the polymerized monomer under enthalpic interaction. For instance, the solvent may be water.

[0061] It is noted that the invention relates to all possible combinations of features recited in the claims.

[0062] BRIEF DESCRIPTION OF THE DRAWINGS

[0063] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

[0064] Fig. 1 schematically depicts an exploded view of different elements comprised by an arrangement according to the invention.

[0065] Fig. 2 schematically depict a cross-section of the arrangement according to Fig. 1 in an assembled and potted condition and forming part of a light generating system.

[0066] Fig. 3 shows a schematic, perspective view of an arrangement according to the invention comprising an electrical arrangement and a housing encapsulated or potted in a potting material.

[0067] Fig. 4 shows the electrical arrangement of the arrangement according to Fig. 3 separated from the potting material after an external influence has been exerted on the potting material.

[0068] Fig. 5 shows chemical formulae for an exemplary potting material in the form of an Epoxy system.

[0069] Fig. 6 shows chemical formulae for exemplary potting materials in the form of three different acrylates, and more particularly A) the bifunctional acrylate hexandiol diacrylate, B) the tetrafunctional acrylate pentaerythritol tetraacrylate (PETA), and C) the trifunctional acrylate Trimethylolpropane triacrylate (TMPTA).

[0070] Fig. 7 shows chemical formulae for an exemplary potting material in the form of a urethane network.

[0071] Fig. 8A shows a flow diagram illustrating a method according to the invention. Fig. 8B shows a flow diagram illustrating exemplary steps of a polymerization step of a method according to Fig. 8A.

[0072] Fig. 9 shows chemical formulae for an exemplary potting material comprising a cross-linked acrylate.

[0073] Fig. 10 shows a chemical reaction scheme and chemical formulae for an exemplary potting material comprising a cross-linked epoxy system.

[0074] Figs. 11 A shows a chemical reaction scheme and chemical formulae for a first exemplary potting material comprising a cross-linked epoxy-amine system.

[0075] Figs. 1 IB shows a chemical reaction scheme and chemical formulae for a second exemplary potting material comprising a cross-linked epoxy-amine system.

[0076] Fig. 12 shows a chemical reaction scheme and chemical formulae for an exemplary liner chain type cross-linked polymer formed by reacting a diol and an isocyanide.

[0077] Fig. 13 shows a chemical reaction scheme and chemical formulae for an exemplary liner chain type cross-linked polymer formed by reacting a reagent and a monomer having at least three reactive groups.

[0078] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

[0079] DETAILED DESCRIPTION

[0080] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0081] The electrical arrangement may comprise a printed circuit board (PCB). The electrical components may be electrically coupled to the PCB. As known in the art, a PCB may mechanically support and electrically connect electronic components or electrical components using electrically conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and / or between sheet layers of a non-conductive substrate (shortly indicated as “track” or “conductive track”); though other options may also be possible. A PCB may comprise one or more electrically conductive tracks, which may, e.g., comprise copper. When there are two or more electrically conductive tracks, two or more tracks may be electrically isolated from each other. Two or more electrically conductive tracks may be electrically isolated from each other but be (temporarily) electrically connected to each other via one or more electrical components. The electrical connection may be temporary, when, e.g., during operation a switch opens or closes an electrical connection. An electrical connection may, e.g., be permanent, when, e.g., an electrical component is configured electrically connected to two electrically conductive tracks. Hence, a PCB may comprise an insulating layer arranged between a substrate and a conductive layer.

[0082] Note that herein the term “electrical component” may also be referred to as “component” and “electronic component”. An (electronic) component, such as a solid state light source, may generally be soldered onto the PCB to both electrically connect and mechanically fasten it to the PCB. For instance, a basic PCB may consist of a flat sheet of insulating material and a layer of copper foil, laminated to the substrate. Chemical etching divides the copper into separate conducting lines called tracks or circuit traces, pads for connections, vias to pass connections between layers of copper, and features such as solid conductive areas for EM shielding or other purposes. The tracks function as wires fixed in place and are insulated from each other by air and the board substrate material. The surface of a PCB may have a coating that protects the copper from corrosion and reduces the chances of solder shorts between traces or undesired electrical contact with stray bare wires. For its function in helping to prevent solder shorts, the coating is called solder resist.

[0083] Hence, the shape of a PCB may in general be plate-like. Especially, the PCB may have a length and a width and a height, wherein an aspect ratio of the length and the height is at least 5, like in the range of 5 - 5000, like 10 - 2500, and wherein an aspect ratio of the width and the height is at least 2, such as an aspect ratio of at least 5, like in the range of 5 - 5000, like 10 - 2500. The terms “length”, “width”, and “height” may also refer to “largest length”, “largest width”, and “largest height”, respectively. The PCB may especially have a rectangular cross-section (such as a square cross-section). The height (or thickness) of the PCB may be selected from the range of 0.2 - 10 mm, such as 0.5 - 5 mm, like 1 - 2 mm.

[0084] The width of the PCB may be selected from the range of 5 - 200 mm, such as 5 - 50 mm. The length of a single printed circuit board area may, e.g., be selected from the range of 10 - 50 mm, such as 15 - 40 mm. The length of the PCB, including a plurality of connected) PCB areas, may, e.g., be selected from the range of 20 - 2000 mm, such as 20 - 1500 mm. Other dimensions may be possible as well. The printed circuit board may comprise a rigid board or a semi-rigid board, or the printed circuit board may be flexible. Note that the term electrical component may especially refer to an electronic component. The electronic component may include an active or a passive electronic component. An active electronic component may be any type of circuit component with the ability to electrically control electron flow (electricity controlling electricity). Examples thereof are diodes, power sources, such as a battery, a piezo-electric device, an integrated circuit (IC), a transistor, and a driver. The electronic component may include a passive electronic component. Components incapable of controlling current by means of another electrical signal are called passive devices. Resistors, capacitors, inductors, transformers, etc. can be considered passive devices. The electronic component may include an RFID radiofrequency identification) chip. A RFID chip may be passive or active. The term “electric component” may also refer to a plurality of alike or a plurality of different electronic components. The electrical arrangement may comprise at least three, such as at least four, such as at least 10 electrical components. The electrical components may at least comprise one or more ICs and one or more resistors. Such electrical component may be an electrical component that during operation generates heat, such as, e.g., a capacitor, an inductor, a voltage regulator, an amplifier circuit, an integrated circuit, a central processing unit, a microprocessor unit, a power transistor, a field-effect transistor (“FET”, especially a metal- oxide semiconductor field-effect transistor (“MOS-FET”)), a transformer, a resistor, or a diode (especially a LED).

[0085] Moreover, such electrical components may be electrical components that are sensitive to heat (i.e., affected in terms of lifespan and / or performance by high temperatures), such as, e.g., a capacitor, a resistor, a diode (such as a crystal diode), a sensor, or a transformer.

[0086] The term “enclose” may relate to an arrangement of elements, wherein a first element may enclose a second element such that the second element is surrounded by the first element and wherein the second element may not be accessible unless via an opening in the first element.

[0087] The electrical arrangement comprises a top surface. The top surface may be especially defined by the support and the one or more electrical components mounted on the support. The electrical arrangement may also comprise a bottom surface. The bottom surface is on the opposite side of the top surface and may also be referred to as the solder side of the electrical arrangement. Typically, most components are mounted on the top surface and little to no components are mounted on the bottom surface. The one or more electrical components protrude from the support. How much each electrical component protrudes depends on the dimensions of the respective electrical component. Different components have different dimensions, such as different width, length and especially height.

[0088] The three-dimensional topology of the top surface is defined by the dimensions of the support, which create a two-dimensional plane having one or more widths and one or more lengths. It is further defined by the locations and dimensions of the one or more electrical components on the support. In areas where no electrical components are mounted, the three-dimensional topology is defined by the support and is flat. Where electrical components are mounted, the three-dimensional topology is defined by the dimensions of the respective components. In other words, the support together with the one or more electrical components create the three-dimensional top surface of the electrical arrangement.

[0089] The housing encloses the potting material. The potting material is positioned such that it is in contact with the top surface of the electrical arrangement, so that heat can be conducted away from the electrical components to the potting material. The potting material and its implementations will be further described in detail below.

[0090] Generally, a monomer is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.

[0091] As used herein, functionality is intended to refer to the presence of functional groups in a molecule. A monofunctional molecule possesses one functional group, a difunctional two, a trifunctional three, and so forth. In relation to monomers, functionality is intended to refer to the monomer’s number of polymerizable groups and affects the formation and the degree of crosslinking of polymers. The functionality of a monomer be defined as the number of bonds that a monomer's repeating unit forms in a polymer with other monomers.

[0092] Referring now to Fig. 1, different elements comprised by an arrangement 1 according to the invention are schematically depicted. The arrangement 1 comprises an electrical arrangement 4, a housing 3, and a potting material 2.

[0093] The arrangement 1 may by way of example and as shown in Fig. 2 form part of a light generating system 1000 comprising a light generating device 100. The light generating device 100 comprises a solid state light source 101. The arrangement 1 is functionally coupled to the light generating device 100. The arrangement 1 may be configured as a driver or a controller for the light generating device 100.

[0094] The housing 3 has an inner surface 31 oriented to provide an inner cavity 30. The inner cavity 30 is enclosing the electrical arrangement 4 and the potting material 2. The housing 3 may comprise one or more housing walls 32, 33. It is apparent to the skilled person that the housing 3 may be selected from a plurality of geometries, for instance a cuboid, a tetrahedron, a pyramid and a prism. Note that the housing wall 32 may refer to all bounding surfaces of the housing except the bottom wall 33, meaning the bottom wall and the top wall of the housing 3 are referred to as housing walls 32. The one or more housing walls 32, 33 may be curved, for example the housing 3 may have a stadium shape. In some embodiments the bottom wall 33 and / or the top wall 32 may be omitted.

[0095] The housing 3 comprises an inner surface 31 to provide an inner cavity 30. Especially, the inner surface 31 may comprise the interior surface of the one or more housing walls 32, 33.

[0096] The electrical arrangement 4 has a top surface 41 having a three-dimensional topology created by one or more electrical components 42 comprised by the electrical arrangement 4. Especially, as depicted in the figure, the electrical components 42 may have different (and unique) dimensions, having different heights, widths, and lengths.

[0097] The electrical arrangement 4 may comprise a support 43 and one or more electrical components 42. Especially, the support 43 may be a structure upon which other elements may be coupled to or configured on. The support 43 may be a printed circuit board (PCB). Furthermore, the electrical arrangement 4 may comprise a plurality of electrical components 42 functionally coupled to the support 43. The electrical components 42 may comprise electrodes or nodes which may be functionally coupled to the support 43. Here, functionally coupled may refer to securing the electrical components 42 to the support 43 such that the electrical components 42 are secured in place with substantially no relative motion between the support 43 and the electrical components 42. The electrical components 42 may be electrically coupled to the support 43. That is, the electrical components 42 may especially be connected to other electrical components 42 via the support. Hence, alternatively or additionally, functionally coupled may refer to electrical contact of the electrical component 42 with one or more electrically conductive tracks comprised by the support 43. Further, the electrical components 42 may especially be connected to a power source via the support 43. The power source may be configured on the support 43. However, alternatively the power source may also be configured external to the support 43.

[0098] The arrangement 1 may comprise non-electrical components (for example struts) to secure the electrical arrangement 4 in place within the housing 3. The electrical arrangement 4 may be configured on the one or more housing walls 32, 33. Alternatively, the electrical arrangement 4 may be a part of the housing wall 32, 33. However, the electrical arrangement 4 may also be configured away from the housing wall 32, 33. For instance, the electrical arrangement 4 may be arranged (by means of struts or standoffs) away from the housing wall 32, 33.

[0099] The potting material 2 is thermally conductive, electrically insulating, and comprises a cross-linked polymer 20. As indicated in the figure, the basic steps of the assembly of the arrangement 1 comprise providing a housing 3 having the electrical arrangement 4 positioned inside its inner cavity 30. To position the potting material 2 it is arranged on at least a part of the top surface 41 of the electrical arrangement 4. By doing so, the potting material 2 is non-elastically compacted so as to follow the contours of the three- dimensional topology of the top surface 41. Hence, the potting material is in thermal contact with the one or more electrical components 42.

[0100] Fig. 2 schematically depicts a cross section of an example of an arrangement 1 according to the invention. The electrical arrangement 4 is positioned inside the inner cavity 30 of the housing 3 and is enclosed by the housing 3. The potting material 2 is positioned on the top surface 41 of the electrical arrangement 4. Fig. 2 shows the potting material 2 in its position after it has been compressed and after polymerization to obtain the cross-linked polymer 20. Suitable methods and examples of polymerization will be described further below. The shape of the potting material 2 follows the contours of the top surface 41 defined by the electrical components 42 comprised by the electrical arrangement 4. The different electrical components 42 have different shapes, different heights, and different locations on the electrical arrangement 4. The properties of the potting material 2 enable the potting material 2 to adapt to the different electrical components 42 and to follow the shape of the electrical components 42 so as to be in thermal contact with the components.

[0101] The potting material 2 may be in thermal contact with one of more surfaces of the electrical components 42. For instance, the potting material 2 may be in physical contact at one or more locations, such as the top surface of the electrical components 42, or one or more side surfaces of the electrical components 42. Electrical components 42 may be mounted with their bottom surface directly on the support 43. However, there may be air gaps 34 located below electrical components 42, in between the component 42 and the support 43. Such air gaps 34 cannot be filled by arranging a potting material 2 on the top surface 41. Hence, in such cases the bottom surface of an electrical component 42 may not be in thermal contact with the potting material 2. In the following, exemplary monomers suitable for use in a potting material 2 of an arrangement 1 according to the present invention will be described with reference to Figs. 5 to 7 and 9 to 13.

[0102] Fig. 5 shows chemical formulae for an exemplary monomer suitable for a potting material 2 in the form of an exemplary Epoxy system. Generally, epoxy systems with any multifunctional epoxy or epoxy resin may be employed. Multifunctional epoxies and epoxy resins include at least bifunctional, trifunctional and tetrafunctional epoxies and epoxy resins.

[0103] In the example shown in Fig. 5, the right hand molecule is that of a trifunctional Epoxy resin. An example of a suitable trifunctional Epoxy resin is Triglycidyl Paraaminophenol (TGPAP). The left hand molecule is Butane- 1,1, 4, 4-tetraamine (C4H14N4). A suitable epoxy system may thus be a cross-linked polymer 20 made by the reaction between these two molecules.

[0104] The cross-linked polymer 20 can also be produced using epoxy system molecules comprising epoxy and curing agents. The curing agents may be aliphatic amines, polyamides, cycloaliphatic amines, aromatic amines, anhydrides, imidazoles, Lewis acids or a combination thereof.

[0105] Fig. 10 shows chemical formulae for an exemplary potting material in the form of another exemplary epoxy system. This epoxy system comprises an anhydrite and an epoxy, which may be reacted to form a cross-linked polymer 20. In Fig. 10, R denotes a reactive or functional group 5. The groups R also form the cross-links 21 between the main polymer strands of the cross-linked polymer 20. Dx denotes the distance between two neighbouring cross-links 21 in the cross-linked polymer 20. Lx denotes the length of the cross-links 21 in the cross-linked polymer 20.

[0106] Figs. 11 A and 1 IB shows chemical formulae for two different exemplary cross-linked polymers 20 for potting materials 2 in the form of yet other exemplary epoxy systems as well as their components before polymerization. Both of these epoxy systems comprise an epoxy and an amine, which may be reacted to form a cross-linked polymer 20. In Figs. 11 A and 1 IB, R denotes a reactive or functional group 5. The groups R also form the cross-links 21 between the main polymer strands of the cross-linked polymer 20.

[0107] Fig. 6 shows chemical formulae for exemplary monomers for use in a potting material 2 in the form of three different suitable acrylates. Generally, any multifunctional acrylate may in principle be used. Molecule A in Fig. 6 illustrates the bifunctional acrylate hexandiol diacrylate. Molecule B in Fig. 6 illustrates the tetrafunctional acrylate pentaerythritol tetraacrylate (PETA). Molecule C in Fig. 6 illustrates the trifunctional acrylate Trimethylolpropane triacrylate (TMPTA).

[0108] Polymerization of multifunctional acrylates may be activated using photo induced radicals or thermally induced radicals.

[0109] Vinyl ethers can also be used for producing networks using cationic polymerization. Siloxanes can also be used.

[0110] In the case of acrylates and vinyl ethers the cross-link density can be calculated according to the equation

[0111] Cross-link density = (2x2+ 3xs+ 4X4) / (XIMI+X2M2+X3M3+X4M4), where Mi, M2, M3 and M4, respectively, are the molecular weight of molecules with one, two, three and four functional groups 5, respectively, and xi, X2, X3 and X4, respectively, are the fraction of these molecules respectively.

[0112] Fig. 9 shows chemical formulae for an exemplary potting material in the form of another exemplary acrylate system.

[0113] In Fig. 9, Ra denotes a reactive or functional group 5 which is a methyl group for methacrylate, and a Hydrogen for acrylate. Rm denotes a group which is obtained using an acrylate with a single reactive group, that is a mono-acrylate such as methyl methacrylate or isobornyl acrylate. Rd denotes a group which is obtained using an acrylate with multiple reactive groups, that is a di acrylate such as hexandiol di acrylate, tri -acrylate or trimethylolpropane triacrylate. The groups denoted Rd also form the cross-links 21 between the main polymer strands of the cross-linked polymer 20. Dx denotes the distance between two neighbouring cross-links 21 in the cross-linked polymer 20.

[0114] Fig. 7 shows chemical formulae for an exemplary potting material 2 in the form of an exemplary urethane network. Generally, urethane networks with any multifunctional urethane may be employed.

[0115] In the example shown in Fig. 7, the right hand molecule is that of a bifunctional urethane exemplified by showing the urethane Methylene Diphenyl Diisocyanate (MDI). The left hand molecule is (2R,3S)-butane-l,2,3,4-tetraol. A suitable urethane network may thus be a cross-linked polymer 20 made by a polymerization reaction between these two molecules. Other useable urethane systems include polols and molecules with isocyanites. Still further, thiolene systems may also be used. Thiolene systems may be obtained by reaction of thiol with vinyl ether or allyl ether and norbornene. Their polymerization may be initiated by photo activated initiators or thermally activated initiators.

[0116] Fig. 12 shows an exemplary liner chain type cross-linked polymer 20 (right hand side of Fig. 12) formed by reacting a diol and an isocyanide (left hand side of Fig. 12). For liner chain type cross-linked polymers, one of the reactants need to have three or more reactive groups. Diamines can also be added to produce x-links.

[0117] In the case of thiolene systems and / or urethane systems with two reactant molecules A and B the cross-link density can be calculated according to the equation:

[0118] Crosslink density = Reactive molecule A and B = (lxsA3 + 2x4A4 + 3xsA5 + lxsB3 + 2X4B4 + 3xsB5) / (xiMiAl + X2M2A2 + IX3M3A3 + 2X4M4A4 + 3xsMsA5 + X1M1BI + X2M2B2 + IX3M3B3 + 2X4M4B4 + 3X5M5B5), where Mi, M2, M3, M4 and Ms, respectively, are the molecular weight of molecules with one, two, three, four and five functional groups 5, respectively, and xi, X2, X3, X4 and xs are the fraction of these molecules respectively, and where A refers to reactive or functional group A, and B refers to reactive or functional group B.

[0119] Fig. 13 shows a chemical reaction scheme and chemical formulae for another exemplary liner chain type cross-linked polymer 20 formed by reacting a reagent and a monomer having at least three reactive groups 5. The reagent is denoted in the form SH-R1- SH, where R1 is a reactive or functional group 5. An example in the form of a tris(hydroxymethyl)amino is shown in Fig. 13. The monomer may by way of the example shown in Fig. 13 be tri -isodecyl trimellitate.

[0120] Turning now to Figs. 8A and 8B, a method according to the invention and for manufacturing an arrangement 1 comprising an electrical arrangement 4, a housing 3, and a potting material 2 will be described. The housing 3 comprises an inner surface 33 oriented to provide an inner cavity 30. The inner cavity 30 encloses the electrical arrangement 4 and the potting material 2. The electrical arrangement 4 comprises a top surface 41 having a three- dimensional topology created by one or more electrical components 42 comprised by the electrical arrangement 4.

[0121] Referring first to Fig. 8A, the method generally, and irrespective of the embodiment, comprises the following steps. First, in step 100, the potting material 2 is provided. The potting material 2 is in the form of a thermally conductive, electrically insulating potting material 2 comprising a cross-linked monomer 20.

[0122] In step 200, the potting material 2 is arranged on at least a part of the top surface 41 of the electrical arrangement 4 such that it follows the contours of the three- dimensional topology of the top surface 41, and such that it is in thermal contact with the one or more electrical components 42.

[0123] In step 300, performed after encapsulating or potting the electrical arrangement 4 and the housing 3, the cross-linkable monomer (20) is polymerized such as to form a cross-linked network in the potting material 2, wherein the cross-linked network thus formed comprises a cross-link density of at least 0.0005 mol / cm3.

[0124] The manufacturing method may further comprise an optional step 400 of introducing a filler material into the cross-linked network of the polymerized potting material 2. The filler material is a material configured to improve the thermal conductivity of the potting material 2. The filler material may be sand, glass or aluminum oxide particles.

[0125] The manufacturing method may further comprise an optional step 500 of adding an additive to the potting material 2. The additive is configured to increase the capability of the monomer of the potting material 2 to absorb water.

[0126] One or both of steps 400 and 500 may be omitted. Step 400 may be performed after any one of steps 100, 200 and 300. Step 500 may be performed after any one of steps 100 and 200.

[0127] Referring now to Fig. 8B, the step 300 of polymerizing the potting material may comprise the following steps.

[0128] In a first version, step 300 may comprise two steps. First, a step 301 of thermally inducing the polymerization of the potting material 2 at a polymerization initiation temperature TP of at least 30, at least 60 or at least 120 degrees Celsius. Subsequently, a step 303 of cooling the potting material 2 to room temperature TR. The polymerization initiation temperature TP of at least 30, at least 60 or at least 120 degrees Celsius may be maintained for at least 30 minutes, at least 60 minutes or at least 120 minutes.

[0129] In a second version, step 300 may comprise three steps. First a step 301 thermally inducing the polymerization of the potting material 2 at a polymerization initiation temperature TP of at least 30, at least 60 or at least 120 degrees Celsius. Subsequently, a step 302 of thermally inducing the polymerization at an elevated temperature TE compared to the polymerization initiation temperature TP. In other words, TE is chosen such that TE > TP. Finally, a step 303 of cooling the potting material 2 to room temperature TR. The polymerization initiation temperature TP may be maintained for at least 5 minutes, at leastlO minutes or at least 30 minutes. The elevated temperature TE may be maintained for between at least 10 minutes, at least 20 minutes or at least 30 minutes.

[0130] With reference to Figs. 3 and 4, a further method according to the invention and for separating an electrical arrangement 4 encapsulated or potted using a method as described with respect to Figs. 8A and 8B above from a potting material 2 will be described.

[0131] The electrical arrangement 4 encapsulated or potted in the potting material is shown in Fig. 3. The method may in one version comprise bursting the potting material by applying a mechanical shock to the potting material 2. The method may in another version comprise bursting the potting material 2 by applying a solvent to the potting material 2. Optionally, the solvent may be applied to the potting material 2 under enthalpic interaction. For instance, the solvent may be water. The result of bursting the potting material 2 is shown in Fig. 4. As may be seen the potting material 2 is then completely separated from the electrical arrangement 4 and the housing 3, such that the potting material 2, the electrical arrangement 4 and the housing 3 may easily be separated from one another for recycling.

[0132] The degree of reaction of reactive groups, forming the cross-linked polymer is at least 70%, at least 80% or at least 90%.

[0133] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0134] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

CLAIMS:

1. A light generating system (1000) comprising (i) a light generating device (100) and (ii) a arrangement (1), wherein the light generating device (100) comprises a solid state light source (101), wherein the arrangement (1) is functionally coupled to the light generating device (100), and wherein the arrangement (1) is configured as a driver or a controller for the light generating device (100), wherein the arrangement (1) comprises an electrical arrangement (4), a housing (3), and a potting material (2), wherein the housing (3) comprises an inner surface (31) oriented to provide an inner cavity (30), wherein the inner cavity is enclosing the electrical arrangement and the potting material, wherein the electrical arrangement (4) comprises a top surface (41) having a three- dimensional topology created by one or more electrical components (42) comprised by the electrical arrangement, wherein the potting material (2) is thermally conductive, electrically insulating, and wherein the potting material comprises a cross-linked polymer (20), wherein the potting material (2) is arranged on at least a part of the top surface (41) of the electrical arrangement such that it follows the contours of the three-dimensional topology of the top surface, wherein the potting material (2) is in thermal contact with the one or more electrical components (42), and wherein the potting material is a brittle material; wherein the brittleness (B) of the cross-linked polymer is higher than l*10'8(%Pa)-1at room temperature TR and / or the cross-linked polymer (20) comprises a notched Izod impact strength at room temperature TR being less than 1 kJ / m2.

2. A light generating system according to claim 1, wherein the cross-linked polymer (20) comprises a notched Izod impact strength at room temperature TR being at least 0.05 kJ / m2.3 A light generating system according to claim 1 or 2, wherein the housing is resilient or wherein the housing comprises a housing layer being resilient.

4. A light generating system according to claim 3, wherein the housing or the housing layer comprises a foam or a rubber material.

5. A light generating system according to any one of the preceding claims, wherein one or more of the following applies: the cross-linked polymer comprises a cross-link density of at least 0.0005 mol / cm3; the degree of reaction of reactive groups, forming the cross-linked polymer (20) is at least than 70%; the minimum distance, defined by the length of the cross-links Dx between main polymer chains of the cross-linked polymer (20) is equal to or less than 50 angstrom (A).

6. A light generating system according to any one of the above claims, wherein the cross-linked polymer (20) is a brittle cross-linked polymer being a rigid, inflexible material that is prone to cracking and breaking when impacted.

7. A light generating system according to any one of the above claims, wherein the potting material (2) is a monomer with multiple functional groups, and wherein the potting material (2) is a monomer chosen from the group comprising epoxy-systems, multifunctional acrylates, urethane systems, thiolene systems and siloxanes.

8. A light generating system according to any one of the above claims, wherein the cross-linked polymer (20) is obtained by thermally induced polymerization of the potting material (2) at a polymerization initiation temperature (TP) of at least 30, at least 60 or at least 120 degrees Celsius followed by cooling to room temperature (TR).

9. A light generating system according to claim 8, wherein the polymerization initiation temperature (TP) of at least 30, at least 60 or at least 120 degrees Celsius is maintained for at least 30 minutes, at least 60 minutes or at least 120 minutes.

10. A light generating system according to 8 or 9, wherein the thermally induced polymerization of the potting material (2) at a polymerization initiation temperature (TP) is followed by thermally induced polymerization at an elevated temperature (TE) compared to the polymerization initiation temperature (TP) before cooling to room temperature (TR).

11. A light generating system according to any one of the preceding claims, wherein the cross-linked polymer (20) comprises a particulate filling material, wherein the particulate filling material comprises a thermally conductive material having a thermal conductivity of at least IW / mK.

12. A light generating system according to claim 11, wherein particles of the particulate filling material have an average particle size in a range from 0.1 mm to 1 mm.

13. A light generating system according to claim 11 or 12, wherein the concentration of particulate filling material has a gradient over the potting material, wherein the highest concentration of particulate filling material close to the one or more electrical components (42).

14. A light generating system according to any one of the claims 2 to 13, wherein the cross-link density has a gradient over the potting material, wherein the highest cross-link density is close to the one or more electrical components (42).

15. A method for manufacturing an arrangement (1) of a light generating system (1000) according to any one of the above claims, the arrangement (1) comprising an electrical arrangement (4), a housing (3), and a potting material (2), the housing (3) comprising an inner surface (31) oriented to provide an inner cavity (30), the inner cavity enclosing the electrical arrangement (4) and the potting material (2), and the electrical arrangement (4) comprising a top surface (41) having a three-dimensional topology created by one or more electrical components (42) comprised by the electrical arrangement, wherein the method comprises: providing (100) the potting material (2) in the form of a thermally conductive, electrically insulating potting material comprising a cross-linkable monomer (20), depositing the cross-linkable monomer into the housing by arranging (200) the potting material (2) on at least a part of the top surface (41) of the electrical arrangement suchthat it follows the contours of the three-dimensional topology of the top surface (41), and such that it is in thermal contact with the one or more electrical components (42), and wherein the method further comprises, after encapsulating or potting the electrical arrangement and the housing: polymerizing (300) the cross-linkable monomer (20) such as to form a crosslinked polymer (20), wherein the potting material (2) with the thus formed cross-linked polymer (20) is a brittle material; wherein the brittleness (B) of the cross-linked polymer is higher than l*10'8(%Pa)-1at room temperature TR and / or the cross-linked polymer (20) comprises a notched Izod impact strength at room temperature TR being less than 1 kJ / m2.

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