Self-healing solder joints in LED applications

Abstract

The invention provides a light generating system (1000) comprising (i) a light generating device (100) comprising a support (800), an electrically conductive track part (810), a solid-state light source (10), a solder joint (820), and (ii) a control system (300); wherein: - the electrically conductive track part (810) is supported by the support (800); wherein the solid-state light source (10) is supported by the support (800) and electrically connected to the electrically conductive track part (810) via the solder joint (820); wherein the solid-state light source (10) is configured to provide light source light (11); and wherein the solid-state light source (10) has a rated peak forward current (IPR); - the control system (300) is configured (i) to operate in a lighting mode of the light generating system (1000) of the solid-state light source (10), and (ii) to execute in a repair mode of the light generating system (1000) an improve action comprising: providing a current pulse to the solid-state light source (10) via the solder joint (820) with an electrical current (IP) larger than the rated peak forward current (IPR) and with a total pulse time (tPT) of at maximum 10 seconds, wherein IP ≥ 1.2*IPR.

Description

[0001] Self-healing solder joints in LED applications

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a light generating system. The invention further relates to a lighting device comprising the light generating system as well as to a method of operating such light generating device.

[0004] BACKGROUND OF THE INVENTION

[0005] There appears to be a desire to improve printed circuits boards or the manufacture thereof. GB2067845, for instance, describes a process for the manufacture of a printed circuit board assembly which includes the steps of: forming on a sheet of insulating material a conductive layer comprising at least one conductive path; testing the conductive path to detect the presence of a defect denoting an imperfection in its conductivity; repairing the conductive path to remedy any detected defect by securing a conductive bridge-piece across the defect by a reflow soldering operation; and encapsulating that area of the conductive path including the repair with a protective layer: prior to continuing the manufacturing process in which subsequent manufacturing steps include the application of heat to the sheet of insulating material and conductive path in the vicinity of the repair.

[0006] US 2018 / 1381761 Al discloses a multi-LED device comprising a transparent substrate, a plurality of light emitting diodes, LEDs, arranged for emitting light of a plurality of colors and disposed on the transparent substrate, an integrated control circuit in connection with the LEDs and comprising a plurality of photo sensors optically connected to the LEDs.

[0007] US2019 / 323666A1 discloses a light emitting diode (LED) module having an elongated flat support with a first long end, a second long end opposite the first long end, and electrically conductive regions.

[0008] WO2021 / 009380 Al discloses a luminaire system including a plurality of LEDs interconnected via connections, a voltage measurement unit, and a gauging means.

[0009] SUMMARY OF THE INVENTION

[0010] As indicated above, there appears to be a desire to improve printed circuits boards or the manufacture thereof. It appears that solder joints may deteriorate during production or during lifetime, leading to failure and reduced lifetime. Hence, it is an aspect of the invention to provide an alternative light generating system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0011] According to a first aspect, the invention provides a light generating system (’’system”) comprising (i) a light generating device, wherein the light generating device comprising a support, an electrically conductive track part, a solid-state light source, a solder joint. Further, the light generating system may comprise a control system. In embodiments, the electrically conductive track part may be supported by the support. Further, the solid-state light source may be supported by the support and electrically connected to the electrically conductive track part via the solder joint. Especially, the solid-state light source may be configured to provide light source light (during operation of the solid-state light source). Further, the solid-state light source may have a rated peak forward current (IPR). In embodiments, the control system may be configured to operate in a lighting mode (or “lighting operation”) of the light generating system the solid-state light source. Further, in embodiments the control system may be configured to execute in a repair mode of the light generating system a (solder) improve action. In specific embodiments, the (solder) improve action may comprise providing a current pulse to the solid-state light source via the solder joint with an electrical (forward) current (Ip) larger than the rated peak forward current (IPR). Further, the total pulse time (tp-r) may in embodiments be at maximum 10 seconds (though longer times are herein not excluded). Yet, in specific embodiments, Ip > 1.2*IPR. Hence, amongst others the invention provides in embodiments a light generating system comprising (i) a light generating device comprising a support, an electrically conductive track part, a solid-state light source, a solder joint, and (ii) a control system; wherein: (A) the electrically conductive track part is supported by the support; wherein the solid-state light source is supported by the support and electrically connected to the electrically conductive track part via the solder joint; wherein the solid-state light source is configured to provide light source light; and wherein the solid-state light source has a rated peak forward current (IPR); and (B) the control system is configured (i) to operate in a lighting mode of the light generating system the solid-state light source, and (ii) to execute in a repair mode of the light generating system a (solder)improve action comprising: providing a current pulse to the solid-state light source via the solder joint with an electrical (forward) current (Ip) larger than the rated peak forward current (IPR) and with a total pulse time (tp ) of at maximum 10 seconds, wherein Ip > 1.2*IPR.

[0012] As indicated above, the light generating system may comprise a light generating device comprising a support, an electrically conductive track part, a solid-state light source, and a solder joint. For instance, the light generating system may comprise a lighting device comprising a printed circuit board and a solid-state light source functionally coupled thereto. The solid-state light source may comprise a light emitting diode, a superluminescent diode, a laser diode, a vertical cavity surface emitting laser (VCSEL), a chips on board (COB) device, a (stacked) multi -junction LED, etc. etc.

[0013] In general, such solid-state light source may be electrically (and physically) coupled to a support, especially a printed circuit board via at least two solder joints. A first solder joint may provide a first electrical connection between a first electrically conductive track part and the solid-state light source and a second solder join may provide a second electrical connection between a second electrically conductive track part and the solid-state light source. A printed circuit board (PCB) may comprise a plurality of electrically conductive track parts. Via the electrically conductive track parts, the solid-state light source may be provided with electrical power.

[0014] Herein, the invention is especially explained in relation to a (first) electrically conductive track part and a (first) solder joint, but the invention may also apply to a (second) electrically conductive track part and a (second) solder joint, directly electrically coupled to the same solid-state light source. Further, the light generating system may comprise a support, such as a PCB, configured to support a plurality of solid-state light sources, each functionally coupled to electrically conductive track parts (comprised by the support, such as a PCB) via solder joints. Of course, the invention may essentially apply to any solder joint electrically connecting a solid-state light source with an electrically conductive track part. Hence, especially the electrically conductive track part may be supported by the support, wherein the solid-state light source may be supported by the support and electrically connected to the electrically conductive track part via the solder joint.

[0015] Especially, the solid-state light source may be configured to provide light source light (i.e. light from the light source). This light may be escape from the light generating system as such. Hence, in embodiments the system light generated by the light generating system (during operation thereof) may comprise (solid state) light source light. However, it may also be possible that at least part of the light source light is converted by a luminescent material into luminescent material light. Hence, in (other) embodiments, the system light generated by the light generating system (during operation thereof) may comprise luminescent material light (and optionally (solid state) light source light). The light source light may especially be visible light, such as blue light. The system light may especially be visible light, and in specific embodiments the system light may be white light, though other embodiments may also be possible.

[0016] A solid-state light source may have a rated forward current (IR). This may be the current where the solid-state light source may be most efficient. However, the solid-state light source may also have a rated peak forward current (IPR). This may be the highest current at which the solid-state light source may be driven, and which should not be exceeded, as otherwise the life-time may substantially be reduced, including early failure. In the present invention, however, it appears that a short current pulse substantially above the rated peak forward current (IPR) may be used to cure solder failure due to e.g. cracks. A too long time exceeding the rated peak forward current (IPR) may be undesirable, and a too high value of the current over the rated peak forward current (IPR) may also be undesirable, but with a deliberate, relatively short pulse, it appears that the solder may temporarily (and locally) melt, leading to (possible) repair of the solder. Hence, such peak, e.g. after a substantial operation time, may increase to total possible operation time, and thus the lifetime.

[0017] Further, the light generating system may comprise a control system. The control system may be configured to operate the solid-state light source (such that light source light may be provided). Hene, light source light may be provided when the solid-state light source is operated during a lighting mode of the light generating system. Such control system may e.g. comprise a driver. However, the control system may also be configured to execute a (solder) improve action, i.e. an action wherein possible deteriorated solder may at least partly be repaired (see also above). Hence, in embodiments the control system may be configured (i) to operate in a lighting mode of the light generating system the solid-state light source, and (ii) to execute in a repair mode of the light generating system a (solder) improve action. Especially, the (solder) improve action may comprise: providing a current pulse to the solid-state light source via the solder joint with an electrical (forward) current (Ip) larger than the rated peak forward current (IPR) and with a total pulse time (tp ) of (especially) at maximum 10 seconds, wherein in specific embodiments Ip > 1.2*IPR. The (solder) improve action may also be indicated as “repair action”.

[0018] Hence, during the total lifetime, in embodiments only during in total 10 seconds or less, one or more pules may be provided wherein Ip > 1.2*IPR applies. The (solder) improve action may be executed once, with a single pulse. In other embodiments, the (solder) improve action may be executed once, though with a plurality of consecutive pulse, which in total may not last more than the total pulse time (tpr) of especially at maximum 10 seconds. Note that the (solder) improve action may in embodiments overlap in time with the lighting mode and may in other embodiments not overlap in time with the lighting mode. Hence, in specific embodiments, the (solder) improve action may at least partly overlap with a lighting mode, and in other embodiments may directly follow on a lighting mode, or be (fully) separated in time from a lighting mode. Some embodiments will be provided below.

[0019] Good results may be obtained with one or more pules wherein the current is at least 50% of the peak forward current. However, pulses larger than about 7 times the peak forward current, like larger than about 6 times the peak forward current could lead to undesired (side) effects. Hence, in embodiments 1.35*IPR < Ip < 6*IPR, more especially 1.5*IPR < IP < 5*IPR.

[0020] Especially, the (solder) improve action may be chosen such that temporarily the solder of the solder joint at least partly melts. This may be controlled by the current of the pulse, the time of a single pulse when a single pulse is applied, the total pulse time of a plurality of pulses when a plurality of pulses is provided within a (relatively short) period. Hence, in embodiments one or more of (i) the electrical (forward) current (Ip) of the current pulse and (ii) the total pulse time (tp-r) may be selected such that the solder joint (temporarily) at least partly melts. The total pulse time may be defined as tp = X tp, wherein tp is the pulse time of individual pulses. When a single pulse is provided, tpT = tp. Further, the number of pulses may be controlled, the pulse time of the individual pulses (when a plurality of pulses is provided), the frequency with which the plurality of pulses is provided (when a plurality of pulses is provided). Hence, in specific embodiments one or more of (i) the electrical (forward) current (Ip) of the current pulse, (ii) the total pulse time (tp ), (iii) a number of current pulses, a pulse time (tp) of the respective number of pulses, and a repetition frequency of the number pulses may be selected such that the solder joint (temporarily) at least partly melts.

[0021] In embodiments, the total pulse time (tp ) may be selected from the range of at maximum 20 seconds, such as at maximum 10 seconds, like selected from the range of about 0.5 ps -5 seconds, like selected from the range of 0.5 ps -1 second, such as up to about 500 ms, more especially I ps - 200 ms. As will be further described below, the (solder) improve action may be executed once or a limited number of times during the lifetime of the solid- state light source. Hence, a ratio of a total time ti the solid-state light source is subjected to Ip > 1.2*IPR, more especially to Ip > 1.5*IPR, to a rated lifetime tp (of the solid-state light source) is R= ti / tL < l*10'6, like R= ti / IL < 3*10'7, more especially R= ti / IL < 3*10'8, like R= ti / IL < l*10'8.

[0022] The control system may be configured to execute the (solder) improve action on the bases of operational parameters of the solid-state light source, like resistance over the solid state light source or intensity of the light escaping from the solid state light source, but may also be con configured to execute the (solder) improve action in dependence of a time parameter like time since first switch on or total operation time. Hence, in embodiments the control system is configured to execute the (solder) improve action in dependence of one or more of (i) a predefined operation condition of the solid-state light source, (ii) a timer, (iii) an optical sensor signal of an optical sensor configured to sense light emanating from the solid-state light source, (iv) an electrical sensor signal of an electrical sensor configured to sense an electrical parameter of at least part of an electrical circuit comprising the electrically conductive track part, the solid-state light source, and the solder joint, and (v) a user input device.

[0023] The predefined operation condition may e.g. be that the solid-state light source is switched on, and that only then the (solder) improve action may be executed. The predefined operation condition may e.g. also be that the solid-state light source receives the instruction to switch off, and that before effectively switching off, the (solder) improve action may be executed. The timer may e.g. imply executing the (solder) improve action after a predetermined total operation time or a predetermined time after a first switch on, like after 10,000 hours total operation time, or like 10,000 hours after a first switch on. The optical sensor may sense a change in the radiant flux over time (e.g. flickering), which may be a signal for the control system to execute the (solder) improve action. The electrical sensor signal may be generated by a separate electronic device, but may also be a control system control of operation of the solid-state light source (e.g. a software routine). For instance, when a resistance changes, this may be measured with a separate device but may also be observed by the control system. Further, in embodiments a user may give instructions to execute the (solder) improve action. For instance, when no light is emanating from the light source, a user may decide to have the (solder) improve action executed, in embodiments wherein the user input device is available and the control system is configured to receive via the user input device such instruction.

[0024] In embodiments, the electrical sensor signal may be selected from the group comprising: a voltage change (especially drop) across the solid state light source, a current through the solid state light source, a temperature of the solid state light source, etc. For instance, the sensor signal may be evaluated relative to earlier sensor signals. When a deviation occurs, this may be indicative of a solder problem, and the (solder) improve action may be executed.

[0025] Hence, in specific embodiments the control system may be configured to execute a (solder) improve action upon a first operation of the solid-state light source.

[0026] Alternatively or additionally, in specific embodiments the control system may be configured to execute the (solder) improve action upon termination of a period of operation (in the lighting mode) of the solid-state light source. Hence, a switching off action may delayed with about the pulse time as the (solder) improve action is executed before actually switching the solid state light source off.

[0027] Alternatively or additionally, in specific embodiments the control system may be configured to execute the (solder) improve action during a period of operation (in the lighting mode) of the solid-state light source. For instance, as indicated above, after 10,000 hours total operation time.

[0028] Alternatively or additionally, in specific embodiments the control system may be configured to execute the (solder) improve action after a predetermined total operation time (in the lighting mode) of the solid-state light source (and to repeat this after each subsequent operation during the (same) predetermined total operation time of the solid-state light source). For instance, as indicated above, after 10,000 hours total operation time, but also after the next 10,000 hours total operation time. In embodiments, the predetermined total operation time (in the lighting mode) of the solid-state light source may be at least 80% of the rated lifetime of the solid-state light source. Of course, it cannot be excluded that after 80% of the rated lifetime of the solid-state light source, the solid-state light source lives (again) longer than 80% of the rated lifetime of the solid-state light source, which may in specific embodiments allow a second (solder) improve action.

[0029] As indicated above, the light generating system may comprise an optical sensor. Hence, in embodiments, the light generating system may comprise the optical sensor, especially configured to sense light emanating from the solid-state light source (in the lighting mode), wherein the light (emanating from the solid-state light source) may be selected from light source light and optional luminescent material light from a (optional) luminescent material configured to convert at least part of the light source light, and wherein the control system may be configured to control the (solder) improve action in dependence of (at least) the optical sensor signal. Alternatively or additionally, the light generating system may comprise the electrical sensor as described above, wherein the electrical sensor may be configured to monitor electrical conductance of the solder joints, wherein the electrical sensor may be selected from a physical electrical sensor and a software routine executed by the control system, and wherein the control system may be configured to control the (solder) improve action in dependence of (at least) the electrical sensor signal.

[0030] Hence, as can be derived from the above, in embodiments only a single, or a limited number of (solder) improve action may be executed during the total lifetime of the solid-state light source. In embodiments, the control system may be configured to execute the (solder) improve action n times during the rated lifetime of the solid-state light source, wherein l<n<5, like l<n<3, more especially l<n<2.

[0031] In embodiments, the light generating system may comprise a lighting device (see also below) comprising the light generating device and the control system. Such lighting device may e.g. be a lamp or a luminaire. Such lighting device may comprise the control system. However, it is also possible that such lighting device may be controlled via a remote control system, e.g. a central lighting control system in an office. However, such lighting device may still comprise control means, like a driver. Hence, in embodiments the control system may comprise a master control system and a slave control system, wherein: the slave control system may be configured (i) to operate the solid-state light source, and (ii) upon instruction of the master control system to execute the (solder) improve action. The slave control system may be comprised by the lighting device.

[0032] In specific embodiments, the light generating system may comprise a flip-chip LED package comprising the electrically conductive track part, the solid-state light source, and the solder joint.

[0033] Of course, in embodiments the light generating system may comprise a plurality of light generating devices, wherein the control system may be configured to control each of the plurality of light generating devices. In embodiments, the (solder) improve action for each solid-state light source may be executed at the same time. However, in other embodiments, the (solder) improve action the solid-state light sources may be executed individually (or sets of solid-state light sources may be subjected to the (solder) improve action individually (i.e. per set)).

[0034] The light generating system may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, (outdoor) road lighting systems, urban lighting systems, green house lighting systems, horticulture lighting, digital projection, or LCD backlighting. The light generating system (or luminaire) may be part of or may be applied in e.g. optical communication systems or disinfection systems.

[0035] The term “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system, which may also be indicated as “controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and / or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface.

[0036] The control system may also be configured to receive and execute instructions from a remote control. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or I-phone, a tablet, etc.. The device is thus not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system.

[0037] Hence, in embodiments the control system may (also) be configured to be controlled by an App on a remote device. In such embodiments the control system of the lighting system may be a slave control system or control in a slave mode. For instance, the lighting system may be identifiable with a code, especially a unique code for the respective lighting system. The control system of the lighting system may be configured to be controlled by an external control system which has access to the lighting system on the basis of knowledge (input by a user interface of with an optical sensor (e.g. QR code reader) of the (unique) code. The lighting system may also comprise means for communicating with other systems or devices, such as on the basis of Bluetooth, Thread, WIFI, LiFi, ZigBee, BLE or WiMAX, or another wireless technology.

[0038] The system, or apparatus, or device may execute an action in a “mode” or “operation mode” or “mode of operation” or “operational mode”. The term “operational mode may also be indicated as “controlling mode”. Likewise, in a method an action or stage, or step may be executed in a “mode” or “operation mode” or “mode of operation” or “operational mode”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another controlling mode, or a plurality of other controlling modes. Likewise, this may not exclude that before executing the mode and / or after executing the mode one or more other modes may be executed.

[0039] However, in embodiments a control system may be available, that is adapted to provide at least the controlling mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to a system, or apparatus, or device, that can only operate in a single operation mode (i.e. “on”, without further tunability).

[0040] Hence, in embodiments, the control system may control in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. The term “timer” may refer to a clock and / or a predetermined time scheme.

[0041] In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc. etc... The lamp or luminaire may further comprise a housing enclosing the light generating system. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. In yet a further aspect, the invention also provides a projection device comprising the light generating system as defined herein. Especially, a projection device or “projector” or “image projector” may be an optical device that projects an image (or moving images) onto a surface, such as e.g. a projection screen. The projection device may include one or more light generating systems such as described herein. Hence, in an aspect the invention also provides a lighting device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system. For instance, in embodiments the lighting device may comprise a housing or a carrier, configured to house or support the herein described support and / or the control system.

[0042] Hence, as can be derived from the above, in yet a further aspect, the invention provides a lighting device selected from the group of a lamp and a luminaire, comprising the light generating system (as described herein). In yet another aspect, the invention provides a lighting device selected from the group of a lamp and a luminaire, comprising the lighting device and the slave control system (as described herein).

[0043] In yet a further aspect, the invention also provides a method of operating a light generating device comprising the support, the electrically conductive track part, the solid-state light source, and the solder joint, as described herein, wherein the method may comprise: (a) providing device light by operating the solid-state light source; and (separated or overlapping in time) (b) executing a (solder) improve action comprising: providing a current pulse to the solid-state light source via the solder joint with an electrical (forward) current (Ip) larger than the rated peak forward current (IPR) and with a total pulse time (tpf) of at maximum 10 seconds; wherein Ip > 1.2*IPR. Embodiments in relation to the light generating system may also apply to the method (and the lighting device, see also above).

[0044] The terms “visible”, “visible light” or “visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm. Herein, UV may especially refer to a wavelength selected from the range of 190-380 nm, such as 200-380 nm. The terms “light” and “radiation” are herein interchangeably used, unless clear from the context that the term “light” only refers to visible light. The terms “light” and “radiation” may thus refer to UV radiation, visible light, and IR radiation. In specific embodiments, especially for lighting applications, the terms “light” and “radiation” refer to (at least) visible light.

[0045] BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0047] Figs, la-ld schematically depict some embodiments, and

[0048] Fig. 2 schematically depict some application embodiments.

[0049] The schematic drawings are not necessarily to scale. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] Figs, la-lb schematically depict some embodiments of a light generating system 1000 comprising a light generating device 100. The light generating device 100 may comprise a support 800, an electrically conductive track part 810, a solid-state light source

[0051] 10, and a solder joint 820. In Fig. la, this is indicated in more detail; Fig. lb schematically depicts the light generating device 100. Further, the light generating system 1000 may comprise a control system 300.

[0052] As schematically depicted, the electrically conductive track part 810 may be supported by the support 800. In Fig. la, schematically two electrically conductive track part 810 are depicted. Further, the solid-state light source 10 may be supported by the support 800 and electrically connected to the electrically conductive track part 810 via the solder joint 820. Especially, the solid-state light source 10 may be configured to provide light source light

[0053] 11. Hence, the device light 101 may comprise in embodiments the light source light 11 (and / or luminescent material light 201 generated by at least partial conversion of the light source light 11, see further also below). The system light 1001 may essentially consist of the device light 101 (which may comprise one or more of first light source light 11 and luminescent material light 201.

[0054] The solid-state light source 10 may have a rated peak forward current IPR.

[0055] The control system 300 may be configured to operate in a lighting mode of the light generating system 1000 the solid-state light source 10. Further, the control system 300 may be configured to execute in a repair mode of the light generating system 1000 a (solder) improve action. See further also Figs. Ic-ld.

[0056] In embodiments, the control system 300 may be configured to execute the (solder) improve action in dependence of a predefined operation condition of the solid-state light source 10. Alternatively or additionally, the control system 300 may be configured to execute the (solder) improve action in dependence of a timer. Alternatively or additionally, the control system 300 may be configured to execute the (solder) improve action in dependence of an optical sensor signal of an optical sensor 310 (see Fig. la) configured to sense light emanating from the solid-state light source 10. Alternatively or additionally, the control system 300 may be configured to execute the (solder) improve action in dependence of an electrical sensor signal of an electrical sensor configured to sense an electrical parameter of at least part of an electrical circuit comprising the electrically conductive track part 810, the solid-state light source 10, and the solder joint 820. Alternatively or additionally, the control system 300 may be configured to execute the (solder) improve action in dependence of a user input device (see Fig. 2, reference 301).

[0057] Hence, in embodiments the light generating system 1000 may comprise such optical sensor 310, configured to sense light emanating from the solid-state light source 10 (in the lighting mode), wherein the light (emanating from the solid-state light source 10) is selected from light source light 11 and optional luminescent material light 201 from a (optional) luminescent material 200 configured to convert at least part of the light source light 11, and wherein the control system 300 is configured to control the (solder) improve action in dependence of (at least) the optical sensor signal. The optional luminescent material 200 is schematically depicted in Fig. la. When no luminescent material 200 is available, the device light 101 may essentially consist of light source light 11. When luminescent material 200 is available, the device light 101 may comprise luminescent material light 201 and optionally light source light 11. As indicated above, the system light may essentially consist of the device light 101.

[0058] Alternatively or additionally, the light generating system 1000 may comprise the electrical sensor, wherein the electrical sensor is configured to monitor electrical conductance of the solder joints 820, wherein the electrical sensor is selected from a physical electrical sensor and a software routine executed by the control system 300, and wherein the control system 300 is configured to control the (solder) improve action in dependence of (at least) the electrical sensor signal. The electrical sensor signal may be selected from the group comprising: a voltage change (especially drop) across the solid state light source, a current through the solid state light source, a temperature of the solid state light source, etc.

[0059] As schematically depicted in Figs, la-lb, the control system 300 may comprise a master control system 1300 and a slave control system 2300, wherein: the slave control system 2300 is configured i to operate the solid-state light source 10, and ii upon instruction of the master control system 1300 to execute the (solder) improve action. Hence, assuming a lamp 1 (or a luminaire), the lighting device 1200 (see Fig. lb) may comprise the entire control system 300 (Fig. la left) or may comprise a slave control system 2300 (Fig. la right).

[0060] In embodiments, the light generating system 1000 may comprise a flip-chip LED package comprising the electrically conductive track part 810, the solid-state light source 10, and the solder joint 820.

[0061] Referring to Fig. lb, in embodiments comprise a plurality of solid state light sources 10. Hence, in embodiments the light generating device 100 may comprise a plurality of solid state light sources 10. Not depicted, but in embodiments the light generating system 1000 may comprise a plurality of light generating devices 100, and wherein the control system 300 is configured to control each of the plurality of light generating devices 100.

[0062] As schematically depicted in Fig. lb (and 2), the invention also provides a lighting device 1200 selected from the group of a lamp 1 and a luminaire 2, comprising the light generating system 1000 as described herein.

[0063] The lighting devices 1200 of Fig. lb are only examples of possible lighting devices. The invention may be applied in all kind of lighting devices (lamps, luminaires, etc.).

[0064] Referring to Figs. Ic-ld several embodiments of the (solder) improve action are schematically depicted. Herein, the (forward) current to the light sources is indicated with undashed rectangular blocks, indicating operation times of the light source. By way of example, the lamp has been switched on and off four times, with different time lengths.

[0065] Further, the (forward) current pulses provided during the (solder) improve action are schematically depicted as block pulses. However, the current pulses are not necessarily block pulses. The current pulses are dashed, and always exceed the current provided during operation. The current provided during operation of the solid state light source may e.g. be the rated forward current, though it is herein also not excluded that the current provided during operation is the rated peak forward current, or a current in between.

[0066] Further, the (forward) current provided during operation may be a constant current, though pulse-width modulation may also be applied. The current of during lighting operation is indicated with IR. During operation, device light 101 may be provided (comprising light source light 11 and / or luminescent material light 201, see also above).

[0067] Especially, the (solder) improve action may comprise: providing a current pulse to the solid-state light source 10 via the solder joint with an electrical (forward) current Ip larger than the rated peak forward current IPR and with a total pulse time tpT of at maximum 10 seconds. In embodiments, the following may apply: Ip > 1.2*IPR. In embodiments, may 1.5*IPR < Ip < 5*IPR. In the schematic drawings, Ip is about 2*IPR., would the light source be operated at the rated peak forward current IPR.

[0068] As indicated above, the control system 300 may be configured to operate in a lighting mode of the light generating system the solid-state light source 10, indicated with IR, and to execute in a repair mode of the light generating system 1000 a (solder) improve action, indicated with Ip. In embodiments or examples I-IV, the (solder) improve action overlaps in time with the lighting mode. In embodiment or example V, after the time of the lighting mode, the (solder) improve action is executed. The difference in time, indicated with At may be 0 ms, i.e. directly adjacent in time. In general, when there is no overlap in time, At< 100 ms. Would there be no overlap in time, it may be desirable to first pre-heat. Hence, referring to example or embodiment I, II, and III, where the lighting mode starts with a (solder) improve action (pulse), it may be desirable to have a (short) pre-heating. As indicated above, the (solder) improve action may lead to the solder joint (temporarily) at least partly melting. The preheating may e.g. be executed at 50-100%, such as at least 50%, but below 100%, like not more than 99%, of the forward current the light source is operated (during the lighting operation), i.e. in Fig. 1c IR. The pre-heating may be executed during a period of e.g. at least 1 second, such as up to about 100 seconds, like up to about 50 seconds.

[0069] Fig. 1c is a relatively schematic drawings. The number of pulses during the rated life time or total lifetime tL, may be limited. For instance, in embodiments the control system may be configured to execute the (solder) improve action n times during the rated lifetime of the solid-state light source 10, wherein l<n<2. Further, the number of times the (solder) improve action may be executed during a total lifetime tL, would such total lifetime exceed the rated lifetime, may still not be more than about 5. However, other values are herein not excluded. Hence, in embodiments a ratio of a total time ti the solid-state light source 10 is subjected to Ip > 1.2*IPR to a rated lifetime tL of the solid-state light source is R= ti / tL < 3*10'7. Would (during the total lifetime) only one (solder) improve action be executed, then ti=tpT.

[0070] As schematically depicted in Fig. Id, the time of a single pulse during the (solder) improve action is tp=tpT (see upper drawing). Would a single (solder) improve action include a plurality of pulses (see lower drawing), the plurality of pulse together provide the total pulse time tpT.

[0071] In Fig. 1c, the schematically depicted single pulses during each (solder) improve action may be single pulses (as depicted) or may consist of a plurality of pulses.

[0072] In embodiments, the total pulse time tpT may be selected from the range of 1 ps - 200 ms.

[0073] Referring to example or embodiment I in Fig. 1c, the control system may be configured to execute a (solder) improve action upon a first operation of the solid-state light source.

[0074] Referring to embodiment or example III, the first and the last operation time period, as well as embodiment or example V, the control system may be configured to execute the (solder) improve action upon termination of a period of operation (in the lighting mode) of the solid-state light source. As indicated above, the operation of the light source and the (solder) improve action may overlap in time, see embodiment III, or may not overlap in time, see embodiment V.

[0075] Referring to example or embodiment II, the control system 300 may be configured to execute the (solder) improve action during a period of operation (in the lighting mode) of the solid-state light source. Hence, after fixed operation times, the (solder) improve action may be executed.

[0076] However, it may also be possible to execute the (solder) improve action after a fixed time, irrespective of the operation time. Hence, referring to example or embodiment III, the control system may be configured to execute the (solder) improve action after a predetermined total operation time (in the lighting mode) of the solid-state light source (and optionally to repeat this after each subsequent operation during the (same) predetermined total operation time of the solid-state light source).

[0077] Referring to examples or embodiments IV and V, schematically a single (solder) improve action over the lifetime is shown.

[0078] In embodiments, the predetermined total operation time (in the lighting mode) of the solid-state light source may be at least 80% of the rated lifetime of the solid-state light source.

[0079] Example or embodiment IV also schematically depicts that the (solder) improve action is executed in dependence of a parameter P. This parameter increases, and after reaching a predetermined value, the (solder) improve action may be executed. This parameter may e.g. be the voltage (drop) over or current through the solid state light source. However, also the temperature of the solid state light source may be used as parameter.

[0080] Referring to Fig. la-ld , the invention thus (also) provides a method of operating a light generating device 100 comprising the support 800, the electrically conductive track part 810, the solid-state light source 10, and the solder joint 820, as described herein, wherein the method comprises: (A) providing device light 101 by operating the solid-state light source 10; and (separated or overlapping in time) (B) executing a (solder) improve action comprising: providing a current pulse to the solid-state light source 10 via the solder joint 820 with an electrical (forward) current Ip larger than the rated peak forward current IPR and with a total pulse time tpT of at maximum 10 seconds; wherein Ip > 1.2*IPR.

[0081] Fig. 2 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000 as described above. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the light generating system 1000. Fig. 2 also schematically depicts an embodiment of lamp 1 comprising the light generating system 1000. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may also comprise the light generating system 1000. Hence, Fig. 2 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system 1000 as described herein. In embodiments, such lighting device may be a lamp 1, a luminaire 2, a projector device 3, a disinfection device, or an optical wireless communication device. Lighting device light escaping from the lighting device 1200 is indicated with reference 1201. Lighting device light 1201 may essentially consist of system light 1001, and may in specific embodiments thus be system light 1001. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor and reference 1310 to a ceiling; reference 1307 refers to a wall.

[0082] The term “plurality” refers to two or more. The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’. The term “and / or” especially relates to one or more of the items mentioned before and after “and / or”. For instance, a phrase “item 1 and / or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species". Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0083] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0084] The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0085] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0086] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In yet a further aspect, the invention (thus) provides a software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein.

[0087] The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0088] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings.

[0089] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A light generating system (1000) comprising (i) a light generating device (100) comprising a support (800), an electrically conductive track part (810), a solid-state light source (10), a solder joint (820), and (ii) a control system (300); wherein: the electrically conductive track part (810) is supported by the support (800); wherein the solid-state light source (10) is supported by the support (800) and electrically connected to the electrically conductive track part (810) via the solder joint (820); wherein the solid-state light source (10) is configured to provide light source light (11); and wherein the solid-state light source (10) has a rated peak forward current (IPR); the control system (300) is configured (i) to operate in a lighting mode of the light generating system (1000) of the solid-state light source (10), and (ii) to execute in a repair mode of the light generating system (1000) an improve action comprising: providing a current pulse to the solid-state light source (10) via the solder joint (820) with an electrical current (Ip) larger than the rated peak forward current (IPR) and with a total pulse time (tpf) of at maximum 10 seconds, wherein Ip > 1.2*IPR, such that the solder joint (820) at least partly melts.

2. The light generating system (1000) according to claim 1, wherein 1.5*IPR < Ip < 5*IPR.

3. The light generating system (1000) according to any one of the preceding claims, wherein one or more of (i) the electrical current (Ip) of the current pulse, (ii) the total pulse time (tpf), (iii) a number of current pulses, a pulse time (tp) of the respective number of pulses, and a repetition frequency of the number pulses, are selected such that the solder joint (820) at least partly melts.

4. The light generating system (1000) according to any one of the preceding claims, wherein the total pulse time (tpf) is selected from the range of 1 ps - 200 ms; wherein a ratio of a total time ti the solid-state light source (10) is subjected to Ip > 1.2*IPR to a rated lifetime tp of the solid-state light source is R= ti / tp < 3*10'7.

5. The light generating system (1000) according to any one of the preceding claims, wherein the control system (300) is configured to execute the improve action in dependence of one or more of: (i) a predefined operation condition of the solid-state light source (10), (ii) a timer, (iii) an optical sensor signal of an optical sensor (310) configured to sense light emanating from the solid-state light source (10), (iv) an electrical sensor signal of an electrical sensor configured to sense an electrical parameter of at least part of an electrical circuit comprising the electrically conductive track part (810), the solid-state light source (10), and the solder joint (820), and (v) a user input device.

6. The light generating system (1000) according to any one of the preceding claims, wherein the control system (300) is configured to execute an improve action upon a first operation of the solid-state light source (10).

7. The light generating system (1000) according to any one of the preceding claims, wherein the control system (300) is configured to execute the improve action upon termination of a period of operation of the solid-state light source (10).

8. The light generating system (1000) according to any one of the preceding claims, wherein the control system (300) is configured to execute the improve action during a period of operation of the solid-state light source (10).

9. The light generating system (1000) according to any one of the preceding claims, wherein the control system (300) is configured to execute the improve action after a predetermined total operation time of the solid-state light source (10).

10. The light generating system (1000) according to any one of the preceding claims, wherein the control system (300) is configured to execute the improve action n times during the rated lifetime of the solid-state light source (10), wherein l<n<2.

11. The light generating system (1000) according to any one of the preceding claims, wherein one or more of the following applies: the light generating system (1000) comprises the optical sensor (310) as defined in in claim 5, configured to sense light emanating from the solid-state light source(10), wherein the light is selected from light source light (11) and optional luminescent material light (201) from a luminescent material (200) configured to convert at least part of the light source light (11), and wherein the control system (300) is configured to control the improve action in dependence of the optical sensor signal; and the light generating system (1000) comprises the electrical sensor as defined in in claim 5, wherein the electrical sensor is configured to monitor electrical conductance of the solder joints (820), wherein the electrical sensor is selected from a physical electrical sensor and a software routine executed by the control system (300), and wherein the control system (300) is configured to control the improve action in dependence of the electrical sensor signal.

12. The light generating system (1000) according to any one of the preceding claims, comprising a flip-chip LED package comprising the electrically conductive track part (810), the solid-state light source (10), and the solder joint (820).

13. The light generating system (1000) according to any one of the preceding claims, comprising a plurality of light generating devices (100), and wherein the control system (300) is configured to control each of the plurality of light generating devices (100).

14. A lighting device (1200) selected from the group of a lamp (1) and a luminaire (2), comprising the light generating system (1000) according to any one of the preceding claims.

15. A method of operating a light generating device (100) comprising the support (800), the electrically conductive track part (810), the solid-state light source (10), and the solder joint (820), according to any one of the preceding claims 1-13, wherein the method comprises: providing device light (101) by operating the solid-state light source (10); and executing an improve action comprising: providing a current pulse to the solid-state light source (10) via the solder joint (820) with an electrical current (Ip) larger than the rated peak forward current (IPR) and with a total pulse time (tp-r) of at maximum 10 seconds; wherein Ip > 1.2*IPR.

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