LED lighting device

Abstract

To provide an LED lighting device that effectively releases heat emitted from an LED single unit.SOLUTION: An LED lighting device includes: an LED single unit for emitting light; a printed circuit board which includes a base plate having first and second surfaces opposite to each other and in which the LED single unit is mounted to the first surface; and a heat radiation plate installed on the second surface to radiate heat that is emitted from the LED single unit, where the printed circuit board and the heat radiation plate are welded and joined to each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an LED lighting device, and more particularly to an LED lighting device that effectively dissipates heat generated from a single LED. [Background technology]

[0002] Light emitting diodes (LEDs) are extremely energy efficient compared to other lighting devices such as fluorescent lamps and incandescent lamps, and other light sources for display devices, and can be used semi-permanently, so that lighting devices using light emitting diodes (LEDs) have been attracting much attention recently. LED lighting devices used in such lighting devices consume less power and have a longer lifespan than existing lamps, and are being considered as a new lighting source that can replace existing lamps.

[0003] In particular, vision inspection systems for factory automation, street lights that illuminate equipment in large plants, and lighthouses that transmit light to long-distance ferries are forced to use very bright lights, requiring multiple high-brightness (watt-class) LEDs.

[0004] In the case of high-brightness LED lighting devices that mount multiple high-brightness LEDs in a small area, there is a risk that the lamp's lifespan will be shortened due to the heat energy emitted when the lamp is turned on. Generally, light-emitting diodes (LEDs) convert 20% of their power consumption into light and 80% into heat, so in order to extend the lifespan of LEDs, it is necessary to dissipate the heat generated inside the LED lighting device to the outside and keep the LED temperature low.

[0005] In general, attempts have been made to improve heat dissipation efficiency by sandwiching thermal pads, thermal grease, thermal tape, etc. between the printed circuit board on which the LEDs are mounted and the heat sink to transfer heat, and pressing them with fastening members such as bolts to increase the thermal contact area. However, thermal pads, etc. have different heat transfer coefficients depending on the manufacturer, and the heat transfer characteristics differ depending on the sandwiching state or assembly state, which makes it difficult to effectively lower the temperature of the LED lighting device and cool it down. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Publication No. 10-2010-0120992 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides an LED lighting device that can effectively dissipate heat generated from a single LED. [Means for solving the problem]

[0008] An LED lighting device according to an embodiment of the present invention comprises an LED element that emits light, and a base plate having opposing first and second surfaces, a printed circuit board on which the LED element is mounted on the first surface, and a heat sink provided on the second surface for dissipating heat generated by the LED element, and the printed circuit board and the heat sink may be joined to each other by welding.

[0009] Here, the LED unit may include a heat transfer pad provided on a lower surface thereof opposite to the first surface of the printed circuit board.

[0010] In addition, the LED unit may include an LED element, and a first electrode pad and a second electrode pad provided on the lower surface for supplying power to the LED element, and the heat transfer pad may be provided away from the first electrode pad and the second electrode pad and made of metal.

[0011] Furthermore, the LED unit may further include a ceramic substrate on which the LED element is mounted, and a first via hole and a second via hole penetrating the ceramic substrate so as to electrically connect the first electrode pad and the second electrode pad to the LED element.

[0012] The printed circuit board may further include a first intermediate pad provided on the first surface and connected to the heat transfer pad, a second intermediate pad provided on the second surface corresponding to the first intermediate pad, and a heat transfer via hole penetrating the base plate to thermally connect the first intermediate pad and the second intermediate pad.

[0013] Here, the first intermediate pad may include a central portion joined to the heat transfer pad, and extension portions connected to both ends of the central portion and extending to both sides.

[0014] Also, the heat transfer pad and the first intermediate pad may be welded to each other by a first solder pattern layer provided between the heat transfer pad and the first intermediate pad.

[0015] Furthermore, the second intermediate pad and the heat sink may be welded to each other by a second solder pattern layer provided between the second intermediate pad and the heat sink and having a planar area even larger than that of the first solder pattern layer.

[0016] Furthermore, the LED lighting device may further include a temperature sensor portion at least partially disposed on the first intermediate pad for measuring a temperature.

[0017] Furthermore, the LED lighting device may further include an air flow generating section that is controlled based on the temperature measured by the temperature sensor section and that generates an air flow toward the heat sink.

[0018] At least one of the printed circuit board and the heat sink may include a positioning portion that determines a joining position between the printed circuit board and the heat sink.

[0019] In addition, an LED lighting device according to another embodiment of the present invention includes an LED unit that emits light, and a base plate having opposing first and second surfaces, a printed circuit board on which the LED unit is mounted on the first surface, a heat sink provided on the second surface to dissipate heat generated from the LED unit and having an upper surface smaller than a lower surface of the printed circuit board, and an intermediate plate provided between the printed circuit board and the heat sink and having a lower surface larger than an upper surface of the heat sink, and the intermediate plate and the circuit board, and the intermediate plate and the heat sink may be joined to each other by welding, respectively.

[0020] Here, the intermediate plate may be made of metal.

[0021] At least one of the upper and lower surfaces of the intermediate plate may be provided with an auxiliary positioning portion that determines the joining position between the intermediate plate and the printed circuit board, or that determines the joining position between the intermediate plate and a heat sink. Effect of the Invention

[0022] In the LED lighting device of the present invention, the printed circuit board on which the LEDs are mounted and the heat sink are joined by welding, so that the heat generated by the LEDs, of which a significant portion of the power consumption is converted into heat, can be quickly transferred to the heat sink, keeping the temperature of the LEDs low and also lengthening the lifespan of the LED lighting device.

[0023] In addition, because the printed circuit board on which the individual LEDs are mounted is joined to the heat sink by welding, there is no need for additional processes such as sandwiching a thermally conductive material such as a separate thermal pad between the printed circuit board and the heat sink, or pressing the printed circuit board and the heat sink together with fastening members. As a result, not only is the LED lighting device easier to assemble and the stability of the assembly improved, but stable heat transfer characteristics are also ensured.

[0024] In addition, a heat transfer pad is formed on the bottom surface of the LED unit mounted on the printed circuit board, and the heat generated from the LED unit can be quickly transferred to the heat sink through the intermediate pad of the printed circuit board joined to the heat transfer pad and the heat transfer via hole.

[0025] Furthermore, by providing a temperature sensor at least partially on the intermediate pad, which is the thermal path through which heat generated from the LED is transmitted to the heat sink, the temperature of the LED or the LED lighting device can be measured with high accuracy, and the temperature of the LED lighting device can be effectively controlled.

[0026] In addition, when the planar areas of the printed circuit board and the heat sink are different, an intermediate plate made of a thermally conductive material can be sandwiched between the printed circuit board and the heat sink to join the printed circuit board and the heat sink. This makes it possible to join multiple heat sinks to the printed circuit board even in the case of a heat sink that has an even smaller planar area than the printed circuit board, thereby making it possible to effectively dissipate heat generated by a single LED to the outside. [Brief description of the drawings]

[0027] [Figure 1] 1 is a perspective view of an LED lighting device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of an LED and a printed circuit board according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram showing a state in which an LED unit is joined to a printed circuit board according to an embodiment of the present invention. [Figure 4]FIG. 4 is a perspective view of an LED lighting device according to another embodiment of the present invention. [Diagram 5] FIG. 4 is a perspective view of an intermediate plate according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, the embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The following embodiments are provided merely to complete the disclosure of the present invention and to fully inform those skilled in the art of the scope of the invention. For ease of explanation, the components in the drawings may be exaggerated or reduced in size. In describing the present invention, the same reference numerals are used for the same components, and the drawings may be partially exaggerated in size to accurately explain the embodiments of the present invention, and the same numerals in the drawings indicate the same components.

[0029] FIG. 1 is a perspective view of an LED lighting device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of an LED unit and a printed circuit board according to an embodiment of the present invention, and FIG. 3 is a diagram showing the bonding state between the LED unit and the printed circuit board according to an embodiment of the present invention.

[0030] 1 to 3, an LED lighting device according to an embodiment of the present invention may include an LED unit 100 that emits light, a base plate 210 having a first surface and a second surface facing each other, a printed circuit board 200 on which the LED unit 100 is mounted on the first surface, and a heat sink 300 provided on the second surface to dissipate heat generated from the LED unit 100. The printed circuit board 200 and the heat sink 300 may be joined to each other by welding.

[0031] The LED unit 100 may include an LED element 110 that converts supplied electrical energy into light energy and emits light. In this case, the LED element 110 may be provided individually for each LED unit 100, or a plurality of LED elements 110 may be provided in an array. The LED element 110 can emit light when power is supplied, and can also emit heat in proportion to the strength of the applied current.

[0032] The printed circuit board 200 is a component that provides a position for mounting the LED unit 100, and may include a base plate 210 having a first surface and a second surface facing each other, and a circuit wiring for supplying power to the LED unit 100. The base plate 210 may be made of FR-4 (Flame Retardant Type 4) made of multiple layers of woven glass fabric (glass fiber woven into a cloth) impregnated with multifunctional epoxy resin to improve light weight and flatness, or may be made of a metal plate with excellent thermal conductivity. The circuit wiring is provided inside or on the surface of the base plate 210, and receives power from an external power supply and supplies it to the LED unit 100.

[0033] The heat sink 300 is provided on the second surface of the base plate 210 opposite to the first surface on which the LED unit 100 is mounted, and can dissipate heat generated from the LED unit 100. The heat sink 300 may be made of a metal material having excellent thermal conductivity, specifically, any one of copper, silver, aluminum, iron, nickel, and tungsten, or an alloy material containing at least one of these. The outer surface of the heat sink 300 may be plated with any one of nickel, silver, and gold, or an alloy material containing at least one of these. The heat sink 300 may have heat dissipation fins of various shapes so that it can be frequently in contact with the outside air to dissipate heat.

[0034] In conventional LED lighting devices, in order to improve heat transfer, thermal pads, thermal grease, thermal tape, etc. are sandwiched between the printed circuit board on which the LEDs are mounted and the heat sink, and the thermal contact area is increased by pressing with fastening members such as bolts. However, thermal pads and the like have limited heat transfer characteristics, and there is a problem that the heat transfer characteristics vary depending on how they are sandwiched between the printed circuit board and the heat sink, and how they are assembled using fastening members, etc.

[0035] In the present invention, the printed circuit board 200 on which the LED unit 100 is mounted and the heat sink 300 are welded together so that the heat generated from the LED unit 100 can be quickly released to the outside. Welding is a method of directly joining the solids by applying heat and pressure to the same or different metal materials, and since the welded printed circuit board 200 and the heat sink 300 are completely thermally and mechanically joined together, the heat generated from the LED unit 100 can be quickly released to the outside through the heat sink 300, and the welded printed circuit board 200 and the heat sink 300 can prevent problems with thermal contact or assembly state even without a separate fastening member.

[0036] The LED unit 100 may include a first electrode pad 121 and a second electrode pad 122 that are provided on a lower surface of the LED unit mounted on the printed circuit board 200 and supply power for emitting light to the LED element 110. The first electrode pad 121 and the second electrode pad 122 are electrically connected to a first wiring part 211 and a second wiring part 212 provided on a base plate 210 of the printed circuit board 200, and can receive power from a power supply part.

[0037] The LED unit 100 may further include a heat transfer pad 130 provided on a lower surface facing the first surface so as to be mounted on the printed circuit board 200. The heat transfer pad 130 may be provided away from the first electrode pad 121 and the second electrode pad 122 so as to be electrically insulated from the first electrode pad 121 and the second electrode pad 122, and may be formed of a thermally conductive metal so as to be capable of rapid heat transfer. The thermally conductive metal may be any one of metal materials selected from the group consisting of copper, silver, aluminum, iron, nickel, and tungsten, or an alloy material containing at least one of these metal materials. A first insulating protection layer may be further formed in the space between the heat transfer pad 130 and the first and second electrode pads 121 and 122.

[0038] In order for the heat generated from the LED unit 100 to be rapidly dissipated through the heat sink 300, a sufficient heat path is required from the LED unit 100, where the heat is mainly generated, to the printed circuit board 200 and the heat sink 300. Therefore, a heat transfer pad 130 is provided on the lower surface of the LED unit, which is the surface where the LED unit 100 is mounted on the printed circuit board 200, to provide a heat path for the heat generated from the LED element 110 to escape to the outside of the LED unit 100. When the heat escapes from the heat transfer pad 130 to the lower printed circuit board 200 and / or the heat sink 300, the heat inside the LED unit 100 is transferred to the heat transfer pad 130, and rapid heat dissipation is possible.

[0039] The LED unit 100 may further include a ceramic substrate 140 on which the LED element 110 is mounted, and a first via hole 141 and a second via hole 142 penetrating the ceramic substrate 140 so as to electrically connect the first electrode pad 121 and the second electrode pad 122 to the LED element 110.

[0040] Watt-class high-brightness LED elements are essential for LED lighting devices that require high brightness, such as lighting for vision inspection systems in factory automation, street lights that illuminate equipment in large plants, and lighthouses that transmit light to long-distance ferries. Since high-brightness LED elements generate very high heat, the LED element 110 may be mounted and supported on a ceramic substrate 140 that can maintain stable mechanical strength even at high temperatures. The ceramic substrate 140 may be made of a material selected from ceramic materials such as alumina, aluminum nitride, and silicon carbide, which are materials that have high strength and excellent thermal conductivity. Since the ceramic substrate 140 has electrical insulation properties, the first electrode pad 121 and the second electrode pad 122, which are the destinations of power supply, can be electrically connected to the LED element 110 using the first via hole 141 and the second via hole 142 formed by filling a through hole penetrating the ceramic substrate 140 with an electrically conductive material (e.g., Cu metal).

[0041] On the other hand, in the present invention, the thicker the ceramic substrate 140, the better its mechanical strength will be. However, in order to minimize the heat transfer path and for the sake of processability in forming through holes such as the first via hole 141 and the second via hole 142, the ceramic substrate 140 cannot be made unnecessarily thick, and may have a thickness of several tens to several hundreds of μm.

[0042] Since the direction in which the heat generated from the LED element 110 is transferred to dissipate is the thickness direction of the ceramic substrate 140, the heat transfer distance through the ceramic substrate 140 having a thickness of several tens to several hundreds of μm is shortened, and as a result, it is possible to achieve rapid heat transfer. Therefore, even without a separate structure that penetrates the ceramic substrate 140 and connects to the heat transfer pad 130, the heat inside the LED unit 100 can be rapidly dissipated through the heat transfer pad 130 provided on the lower surface of the LED unit 100.

[0043] The LED unit 100 may further include a molding member that seals the LED element 110 to protect it, or a lens unit 150 that controls the optical path, such as by concentrating the path of light emitted from the LED element 110. The n-electrode and p-electrode arranged on the LED element 110 can be connected to the first via hole 141 and the second via hole 142 by the first connection electrode 111 and the second connection electrode 112, respectively. In the case of a high-luminance LED element 110, a high current must be passed to show high luminance, so the first connection electrode 111 and the second connection electrode 112 can be connected to the n-electrode and the p-electrode by a ball gate array (BGA) method, respectively.

[0044] The printed circuit board 200 may further include a first intermediate pad 221 provided on the first surface and joined to the heat transfer pad 130, a second intermediate pad 222 provided on the second surface corresponding to the first intermediate pad 221, and a heat transfer via hole 230 penetrating the base plate 210 to thermally connect the first intermediate pad 221 and the second intermediate pad 222.

[0045] Even if the heat transfer pad 130 is provided to provide a path for quickly transferring heat inside the LED unit 100, the heat transfer from the heat transfer pad 130 must escape to the outside before the LED lighting device can smoothly dissipate heat. Therefore, a heat transfer path must be secured to transfer heat quickly to the heat sink 300 via the printed circuit board 200 on which the LED unit 100 is mounted. If the first intermediate pad 221 provided on the first surface of the base plate 210 is joined to the heat transfer pad 130, the heat transferred through the heat transfer pad 130 is quickly transferred to the first intermediate pad 221, and the heat can be very quickly transferred to the bottom of the printed circuit board 200 via the heat transfer via hole 230 and the second intermediate pad 222 connected to the first intermediate pad 221. In this case, the first intermediate pad 221, the heat transfer via hole 230, and the second intermediate pad 222 may be made of a metal such as copper that has excellent thermal conductivity.

[0046] In the printed circuit board 200, the first wiring section 211 and the second wiring section 212, which transmit and receive electrical signals, need to be electrically insulated from each other in order to transmit independent electrical signals without interference, and therefore have a multi-layer structure that extends not only in the thickness (vertical) direction, which is the direction of heat transfer, but also in the horizontal direction. Even in the case of the first wiring section 211 and the second wiring section 212, since they are made of copper metal, which is an electrically conductive material, they have excellent thermal conductivity, but due to their three-dimensional structure for transmitting electrical signals, they may not be suitable for heat transfer toward the heat sink 300. In contrast, the heat transfer via hole 230 is a hole that penetrates the base plate 210 in the thickness (vertical) direction, and a heat conductive material is filled in the hole, which penetrates the base plate 210 in the thickness (vertical) direction, to connect the first intermediate pad 221 and the second intermediate pad 222 formed on the first surface and the second surface of the base plate 210, thereby forming a heat transfer path with the shortest distance, and it is possible to perform rapid heat transfer.

[0047] The heat transferred from the heat transfer pad 130 can be quickly transferred in the vertical direction through the first intermediate pad 221, the heat transfer via hole 230, and the second intermediate pad 222. However, if the heat is also quickly transferred in the horizontal direction through the first intermediate pad 221 provided on the first surface of the base plate 210, the heat transferred from the heat transfer pad 130 can be dissipated more effectively. For this purpose, the first intermediate pad 221 may include a central portion 221a joined to the heat transfer pad 130, and extension portions 221b connected to both ends of the central portion 221a and extending to both sides.

[0048] The central portion 221a of the first intermediate pad 221 may be directly in contact with and bonded to the heat transfer pad 130, and the heat transferred to the central portion 221a can be quickly transferred by spreading in the first direction along the central portion 221a extending in the first direction and spreading from both ends of the central portion 221a to the extension portions 221b extending on both sides in a second direction intersecting the first direction. The central portion 221a bonded to the heat transfer pad 130 provided on the lower surface of the compact-sized LED unit 100 has a narrow width, but the extension portions 221b provided on the outside of the LED unit 100 can be spread on both sides to provide a wide heat transfer area.

[0049] The second intermediate pad 222 receives heat from the first intermediate pad 221 and transmits it to the heat sink 300, so the second intermediate pad 222 may have a central portion 222a and extension portions 222b extending from both ends of the central portion to have the same shape as the first intermediate pad 221. Since there is a larger marginal space on the second surface than on the first surface of the base plate 210 including the structure for mounting the LED units 100 such as the first wiring portion 211 and the second wiring portion 212, the second intermediate pad 222 can have a larger planar area including the shape of the first intermediate pad 221.

[0050] The heat transfer via holes 230 connecting the first intermediate pad 221 and the second intermediate pad 222 may be provided in a plurality of holes for more effective heat transfer. The heat transfer via holes 230 may be formed with a uniform density over the central portion 221a and the extended portion 221b of the first intermediate pad 221, or may be formed with different densities in the central portion 221a and the extended portion 221b of the first intermediate pad 221. The central portion 221a, to which the heat of the LED unit 100 is directly transferred, may have the heat transfer via holes 230 with a relatively high density or a relatively wide average effective area per unit area so that more heat can be spread downwards quickly, and the extended portion 221b, which may have a relatively low temperature due to heat transferred in the horizontal direction, may have the heat transfer via holes 230 with a lower density or a narrower average effective area per unit area than the central portion 221a. The average effective area per unit area refers to the sum of the horizontal cross-sectional areas of the heat transfer via holes 230 per unit area. For example, when the shapes of the heat transfer via holes 230 are the same, the heat transfer via holes 230 may be provided with a higher density in the central portion 221a than in the expanded portion 221b.

[0051] The heat transfer pad 130 and the first intermediate pad 221 can be welded to each other by a first solder pattern layer 261 provided between the heat transfer pad 130 and the first intermediate pad 221. By joining the heat transfer pad 130 and the first intermediate pad 221 by welding, a mechanical and thermal connection is realized, and the heat transferred to the heat transfer pad 130 can be quickly transferred to the first intermediate pad 221.

[0052] The heat transfer pad 130 and the first intermediate pad 221 may be joined by forming a first solder paste pattern layer on the first intermediate pad 221 of the printed circuit board 200 using a lead-containing solder paste or a lead-free solder paste, and then forming a first solder pattern layer 261 by a reflow process. In order to mount the LED unit 100 on the printed circuit board 200, the first electrode pad 121 and the second electrode pad 122 of the LED unit 100 may be joined to the first wiring portion 211 and the second wiring portion 212 of the printed circuit board 100 by the first electrode solder pattern layer 251 and the second electrode solder pattern layer 252, respectively, and at the same time, the heat transfer pad 130 and the first intermediate pad 221 may be joined by the first solder pattern layer 261. Since not only the first intermediate pad 221 but also the first wiring portion 211 and the second wiring portion 212 are located on the mounting surface of the printed circuit board 200, a pattern mask can be used to print the first solder paste pattern layer on the first intermediate pad 221 without forming it on the first wiring portion 211 and the second wiring portion 212, thereby maintaining insulation between them.

[0053] The second intermediate pad 222 and the heat sink 300 may be welded to each other by a second solder pattern layer 262 provided between the second intermediate pad 222 and the heat sink 300 and having a larger planar area than the first solder pattern layer 261. After forming a second solder paste pattern layer using lead-containing solder paste or lead-free solder paste on the second intermediate pad 222 of the printed circuit board 200, the second solder pattern layer 262 may be formed by a reflow process, and the printed circuit board 200 and the heat sink 300 may be solder-welded to each other and joined to each other. Since there is no structure for mounting the LED units 100 on the second surface of the base plate 210, the surplus space is relatively large. Therefore, in order to increase the thermal contact area so that the heat transferred from the second intermediate pad 222 can be quickly transferred to the heat sink 300, the planar area of ​​the second solder pattern layer 262 may be formed to be larger than that of the first solder pattern layer 261. In order to stably maintain the mechanical and thermal bond between the printed circuit board 200 and the heat sink 300, the second solder pattern layer 262 may be formed over the entire lower surface of the printed circuit board 200, or may be formed in a pattern large enough to allow multiple second intermediate pads 222 to be commonly applied thereto.

[0054] Meanwhile, the base plate 210 and / or heat sink 300 constituting a metal PCB (printed circuit board) are generally made of aluminum or an aluminum alloy, which has excellent mechanical strength and thermal conductivity, but in the case of aluminum or an aluminum alloy, the joining may not be performed well due to lead or lead-free solder (soldering). In the case of a metal PCB (printed circuit board), the second surface of the base plate 210 may be formed of aluminum or an aluminum alloy, and in such a case, the second intermediate pad 222 may be omitted, or the second intermediate pad 222 may be further provided for more effective heat dissipation. Since the second solder pattern layer 262 is also provided on the second surface of the base plate 210 regardless of the presence or absence of the second intermediate pad 222, when the base plate 210 is made of aluminum or an aluminum alloy, a nickel coating layer may be formed on the second surface of the base plate 210 so that the printed circuit board 200 and the heat sink 300 can be stably joined together, and the nickel may form a solid during the reflow process to ensure a strong solder joint. Needless to say, in the case of the heat sink 300 made of aluminum or an aluminum alloy, a nickel coating layer may also be formed on the joint surface (or upper surface) of the heat sink 300 for a strong solder joint.

[0055] At least one of the printed circuit board 200 and the heat sink 300 may include a positioning portion 240 that determines the joining position between the printed circuit board 200 and the heat sink 300 .

[0056] If the second solder pattern layer 262 is formed to have a larger planar area than the first solder pattern layer 261 for stable bonding between the printed circuit board 200 and the heat sink 300, the printed circuit board 200 and the heat sink 300 may slip from each other and become displaced from their fixed positions while the second solder paste pattern layer is at least partially melted during the reflow process. In contrast, the first solder paste pattern layer formed between the heat transfer pad 130 and the first intermediate pad 221 has a relatively small planar area and the size of the LED unit 100 is also small, so that even if it is partially melted during the reflow process, the LED unit 100 and the printed circuit board may not slip. If the printed circuit board 200 and the heat sink 300 are displaced from their fixed positions, the heat transfer area from the LED unit 100 may be relatively reduced, which may prevent heat from being released quickly. A positioning portion 240 may be formed on at least one of the printed circuit board 200 and the heat sink 300 so that the printed circuit board 200 and the heat sink 300 can be joined at an accurate joining position without shifting from their fixed positions even during the reflow process.

[0057] The positioning portion 240 may be provided in the shape of a recess and a protrusion that fit together at the joining position between the printed circuit board 200 and the heat sink 300. For example, recesses (or protrusions) may be formed near the four corners of the printed circuit board 200, and protrusions (or recesses) may be formed at positions corresponding to the recesses on the joining surface of the heat sink 300. A through hole may be formed in the printed circuit board 200 instead of a recess, or a part of the upper side of the through hole may be filled with a filling material. Alternatively, a stepped positioning portion 240 may be formed on the joining surface of the heat sink 300 so as to correspond to the peripheral portion of the printed circuit board 200, or holes or recesses may be formed at corresponding positions of the printed circuit board 200 and the heat sink 300, and the positioning portion 240 may be provided in the shape of a fixing pin that is inserted into the hole or recess.

[0058] Furthermore, by configuring the positioning portions 240 formed near the four corner portions of the printed circuit board 200 with different positions on the top and bottom on a plane (for example, by forming a concave portion on the top side and a convex portion on the bottom side), the up-down, left-right and right directions on the plane in which the printed circuit board 200 is joined to the heat sink 300 can also be determined by a simple method.

[0059] The LED lighting device according to the present invention may further include a temperature sensor unit 400 that is at least partially provided on the first intermediate pad 221 of the printed circuit board 200 to measure the temperature. Since the life and light emitting characteristics of the LED lighting device may vary depending on the temperature of the LED element 110, it is necessary to monitor the temperature of the LED element 110 in order to manage the performance of the LED lighting device. Although it is most effective to measure the temperature by approaching the LED element 110, since the LED element 110 is provided inside the LED unit 100 and the LED unit 100 is also mounted on the printed circuit board 200, it is not easy to attach a temperature sensor unit that measures the temperature without interfering with the progress of the light emitted from the LED unit 100. In the present invention, since the first intermediate pad 221 is the position closest to the LED unit 100 on the heat path that dissipates the heat generated from the LED unit 100 to the outside, the temperature sensor unit 400 is provided on the first intermediate pad 221 to accurately measure the temperature of the LED unit 100 or the LED element 110.

[0060] Since the heat transfer pad 130 is connected to the central portion 221a of the first intermediate pad 221, the temperature sensor unit 400 may be connected to both ends of the central portion 221a and provided on the extension portion 221b, or the temperature sensor unit 400 may be provided so as to overlap on the extension portions 221b of adjacent first intermediate pads 221 to measure the average temperature of multiple LED units 100.

[0061] The LED lighting device according to the present invention may further include an air flow generating section (not shown) that is controlled based on the temperature measured by the temperature sensor section 400 and generates an air flow toward the heat sink 300.

[0062] In order to manage the performance of the LED lighting device, the temperature sensor unit 400 monitors the temperature of the LED unit 100 or the LED element 110, and the amount of air generated by the air flow generating unit and directed to the heat sink 300 can be adjusted based on the temperature measured by the temperature sensor unit 400. When the temperature of the LED unit 100 is not high, the heat generated from the LED unit 100 can be naturally dissipated by heat exchange with the atmosphere through the heat sink 300. However, when the temperature of the LED unit 100 becomes higher than a predetermined temperature, there is a limit to heat dissipation by natural convection, so that the air flow generating unit is used to generate forced convection so that the air flow is directed to the heat sink 300 to cause rapid heat exchange. The air flow generating unit is a device that forcibly moves air, such as a fan or a blower, and can adjust the amount of air directed to the heat sink 300 by changing the rotation speed of the fan based on the temperature measured by the temperature sensor unit 400. A controller (not shown) connected to the temperature sensor unit 400 and the air flow generating unit and controlling the air flow generating unit using the temperature measured by the temperature sensor unit 400 may be mounted on the printed circuit board 200 or may be provided separately.

[0063] FIG. 4 is a perspective view of an LED lighting device according to another embodiment of the present invention, and FIG. 5 is a perspective view of an intermediate plate according to another embodiment of the present invention.

[0064] An LED lighting device according to another embodiment of the present invention includes an LED unit 100 that emits light, a base plate 210 having opposing first and second surfaces, a printed circuit board 200 on which the LED unit 100 is mounted on the first surface, a heat sink 300 that is provided on the second surface to dissipate heat generated from the LED unit 100 and has an upper surface smaller than a lower surface of the printed circuit board 200, and an intermediate plate 500 that is provided between the printed circuit board 200 and the heat sink 300 and has a lower surface larger than an upper surface of the heat sink 300, and the intermediate plate 500 and the circuit board 200, and the intermediate plate 500 and the heat sink 300 may be joined to each other by welding, respectively.

[0065] In describing the LED lighting device according to another embodiment of the present invention, the same points as those described above regarding the LED lighting device according to the embodiment of the present invention will be omitted.

[0066] The printed circuit board 200 on which the LED elements 100 are mounted may be provided in a number of sheets according to the amount of light required for the LED lighting device, and the heat sink 300 may also be provided in a number of sheets according to the amount of heat to be dissipated. When the area of ​​the lower surface of the printed circuit board 200 is smaller than the area of ​​the upper surface of the heat sink 300 (for example, see FIG. 1), the heat can be dissipated more quickly, so there is no thermal problem. However, when the area of ​​the lower surface of the printed circuit board 200 is larger than the area of ​​the upper surface of the heat sink 300, the heat of the LED elements 100 located above the area where the printed circuit board 200 and the heat sink 300 do not abut each other may not be dissipated sufficiently. Even when the printed circuit board 200 having a larger lower surface is joined to the multiple heat sinks 300, a space is inevitably created between the multiple heat sinks 300, so the heat of the LED elements 100 located above the space may not be dissipated sufficiently. This situation can occur frequently when a commercially available heat sink is used rather than having a separate heat sink fabricated to fit the shape and size of the printed circuit board.

[0067] In order to solve this problem, in the present invention, an intermediate plate 500 having a lower surface larger than the upper surface of the heat sink 300 is sandwiched between the printed circuit board 200 and the heat sink 300 to suppress the deterioration of the heat dissipation characteristics of the LED unit 100 that may occur depending on the difference in the area of ​​the joint surface between the printed circuit board 200 and the heat sink 300. Since the intermediate plate 500 covers the upper part of the space between the multiple heat sinks 300, all the LED units 100 mounted on the printed circuit board 200 can exhibit uniform heat dissipation characteristics.

[0068] In order to allow heat transferred from the printed circuit board 200 on which the LED units 100 are mounted to be rapidly transferred to the heat sink 300, the intermediate plate 500 is welded to the circuit board 200 and the intermediate plate 500 is welded to the heat sink 300, so that the welded printed circuit board 200, intermediate plate 500, and heat sink 300 are completely integrated thermally and mechanically. As a result, heat generated from the LED units 100 can be rapidly dissipated to the outside through the heat sink 300, and the welded printed circuit board 200, intermediate plate 500, and heat sink 300 can suppress problems in thermal contact or assembly state without a separate thermal pad or fastening member.

[0069] In this case, the intermediate plate 500 may be made of a thermally conductive metal so that the heat transferred from the upper printed circuit board 200 to the lower heat sink 300 can be quickly transferred, and the heat can also be quickly spread horizontally between the heat sinks 300 to ensure a certain degree of heat transfer. The intermediate plate 500 may be made of a metal material having excellent thermal conductivity, specifically, any one of copper, silver, aluminum, iron, nickel, and tungsten, or an alloy material containing at least one of these metals. A nickel layer or a nickel alloy layer may be formed on the outer surface of the intermediate plate for strong soldering.

[0070] At least one of the upper and lower surfaces of the intermediate plate 500 may be provided with auxiliary positioning portions 511-514, 521-524 that determine the joining position between the intermediate plate 500 and the printed circuit board 200, or that determine the joining position between the intermediate plate 500 and the heat sink 300.

[0071] An intermediate solder pattern layer may be formed between the printed circuit board 200 and the intermediate plate 500, and between the intermediate plate 500 and the heat sink 300, and then a reflow process of heat treatment may be used to form an intermediate solder pattern layer to solder the printed circuit board 200 and the intermediate plate 500, and the intermediate plate 500 and the heat sink 300, respectively, but for stable bonding, the intermediate solder pattern layer formed on the upper and lower surfaces of the intermediate plate 500 may have a larger planar area than the first solder pattern layer 261. For example, the intermediate solder pattern layer may be formed on the entire upper and lower surfaces of the intermediate plate 500.

[0072] During the reflow process, the intermediate solder paste pattern layer is at least partially melted, and the printed circuit board 200 and the intermediate plate 500, and / or the intermediate plate 500 and the heat sink 300 may slip relative to each other and become displaced from their fixed positions. If the printed circuit board 200, the intermediate plate 500, and the heat sink 300 are displaced from their fixed positions, the area of ​​heat transfer from the LED unit 100 may be relatively reduced, and the heat may not be able to escape quickly. To solve this problem, auxiliary positioning parts 511-514, 521-524 are formed on at least one of the upper surface and the lower surface of the intermediate plate 500, so that the printed circuit board 200, the intermediate plate 500, and the heat sink 300 can be bonded at accurate bonding positions without being displaced from their fixed positions during the reflow process.

[0073] The auxiliary positioning portions 511-514, 521-524 may be provided in the shape of a recess or protrusion that fits into each other at the joining positions between the printed circuit boards 200 or the heat sink 300 and the intermediate plate 500. For example, when joining a plurality of printed circuit boards 200 to the upper surface of the intermediate plate 500, recesses (or protrusions) may be formed near the four corners of each of the printed circuit boards 200, and protrusions (or recesses) may be formed at corresponding positions on the upper surface of the intermediate plate 500. Similarly, auxiliary positioning portions in the shape of recesses and protrusions may be formed at corresponding positions on the lower surface of the intermediate plate 500 and the upper surfaces of the plurality of heat sinks 300.

[0074] Through holes may be formed in place of recesses in the printed circuit board 200 or the intermediate plate 500, and a part of the upper side of the through holes may be filled with a filler. Alternatively, stepped auxiliary positioning portions 511-514, 521-524 may be formed on the joint surface of the intermediate plate 500 so as to correspond to the peripheral portions of the printed circuit board 200 and the heat sink 300, or holes or recesses may be formed at corresponding positions of the printed circuit board 200, the intermediate plate 500, and the heat sink 300, and auxiliary positioning portions in the form of fixing pins to be inserted into the holes or recesses may be provided.

[0075] The positioning portions 240 formed near the four corners of the printed circuit board 200 may be configured with the top and bottom differing on a plane (for example, by forming a concave portion on the top and a convex portion on the bottom), and auxiliary positioning portions may be provided on the upper surface of the intermediate plate 500 with the top and bottom differing on a plane so as to correspond to the positioning portions 240 of the printed circuit board 200. With this configuration, the top, bottom, left and right directions on a plane of the intermediate plate 500 and the printed circuit board 200 to be joined can be easily determined and joined.

[0076] In the LED lighting device of the present invention, the printed circuit board on which the LEDs are mounted and the heat sink are joined by welding, so that the heat generated by the LEDs, of which a significant portion of the power consumption is converted into heat, can be quickly transferred to the heat sink, keeping the temperature of the LEDs low and also lengthening the lifespan of the LED lighting device.

[0077] In addition, because the printed circuit board on which the individual LEDs are mounted is joined to the heat sink by welding, there is no need for additional processes such as sandwiching a thermally conductive material such as a separate thermal pad between the printed circuit board and the heat sink, or pressing the printed circuit board and the heat sink together with fastening members. As a result, not only is the LED lighting device easier to assemble and the stability of the assembly improved, but stable heat transfer characteristics are also ensured.

[0078] In addition, a heat transfer pad is formed on the bottom surface of the LED unit mounted on the printed circuit board, and the heat generated from the LED unit can be quickly transferred to the heat sink through the intermediate pad of the printed circuit board joined to the heat transfer pad and the heat transfer via hole.

[0079] Furthermore, by providing a temperature sensor at least partially on the intermediate pad, which is the thermal path through which heat generated from the LED is transmitted to the heat sink, the temperature of the LED or the LED lighting device can be measured with high accuracy, and the temperature of the LED lighting device can be effectively controlled.

[0080] In addition, when the planar areas of the printed circuit board and the heat sink are different, an intermediate plate made of a thermally conductive material can be sandwiched between the printed circuit board and the heat sink to join the printed circuit board and the heat sink. This makes it possible to join multiple heat sinks to the printed circuit board even in the case of a heat sink that has an even smaller planar area than the printed circuit board, thereby making it possible to effectively dissipate heat generated by a single LED to the outside.

[0081] The term "on" used in the above description means that it is in direct contact with something and that it is located opposite the upper or lower part without direct contact, and it can be located not only opposite the entire upper or lower part, but also partially opposite, and is used to mean that it is located opposite to the upper or lower part at a distance or in direct contact with the upper or lower part. In addition, the terms "upper", "lower", "front end", "rear end", "upper part", "lower part", "top end", "bottom end", etc. used in the above description are defined based on the drawings for ease of explanation, and these terms do not limit the shape and position of each component.

[0082] Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the above embodiments, and it should be understood that various modified embodiments and other equivalent embodiments can be adopted by those skilled in the art without departing from the gist of the present invention as claimed in the claims. Therefore, the true technical scope of protection of the present invention should be determined by the appended claims. [Explanation of symbols]

[0083] 100: LED only 200: Printed circuit board 300: Heat sink 400: Temperature sensor part 500: Intermediate plate

Claims

1. A single LED that emits light, a printed circuit board including a base plate having a first surface and a second surface opposed to each other, the LED unit being mounted on the first surface; a heat sink provided on the second surface to dissipate heat generated from the LEDs; Equipped with The LED lighting device, wherein the printed circuit board and the heat sink are joined to each other by welding.

2. A single LED that emits light, a printed circuit board including a base plate having a first surface and a second surface opposed to each other, the LED unit being mounted on the first surface; a heat sink disposed on the second surface to dissipate heat generated by the LEDs, the heat sink having an upper surface smaller than a lower surface of the printed circuit board; an intermediate plate disposed between the printed circuit board and the heat sink, the intermediate plate having a lower surface larger than an upper surface of the heat sink; Equipped with The intermediate plate and the circuit board, and the intermediate plate and the heat sink are respectively welded to each other.

3. The LED unit is 3. The LED lighting device according to claim 1, further comprising a heat transfer pad provided on a lower surface of the printed circuit board opposite to the first surface.

4. The LED unit is An LED element, a first electrode pad and a second electrode pad provided on the lower surface to supply power to the LED element; Equipped with 4. The LED lighting device according to claim 3, wherein the heat transfer pad is provided apart from the first electrode pad and the second electrode pad, and is made of metal.

5. The LED unit is a ceramic substrate on which the LED element is mounted; a first via hole and a second via hole penetrating the ceramic substrate so as to electrically connect the first electrode pad and the second electrode pad to the LED element; The LED lighting device of claim 4 further comprising:

6. The printed circuit board comprises: a first intermediate pad provided on the first surface and connected to the heat transfer pad; a second intermediate pad provided on the second surface to correspond to the first intermediate pad; a heat transfer via hole passing through the base plate to thermally connect the first intermediate pad and the second intermediate pad; The LED lighting device of claim 3 further comprising:

7. The first intermediate pad comprises: A central portion joined to the heat transfer pad; extension portions connected to both ends of the central portion and extending to both sides; 7. The LED lighting device according to claim 6, comprising:

8. 7. The LED lighting device according to claim 6, wherein the heat transfer pad and the first intermediate pad are welded to each other by a first solder pattern layer provided between the heat transfer pad and the first intermediate pad.

9. 9. The LED lighting device according to claim 8, wherein the second intermediate pad and the heat sink are welded to each other by a second solder pattern layer provided between the second intermediate pad and the heat sink and having a planar area larger than that of the first solder pattern layer.

10. 7. The LED lighting device according to claim 6, further comprising a temperature sensor portion at least partially disposed on the first intermediate pad for measuring a temperature.

11. 11. The LED lighting device according to claim 10, further comprising an air flow generating section controlled based on the temperature measured by the temperature sensor section and generating an air flow toward the heat sink.

12. The LED lighting device according to claim 1 , wherein at least one of the printed circuit board and the heat sink is provided with a positioning portion that determines a joining position between the printed circuit board and the heat sink.

13. The LED lighting device according to claim 2 , wherein the intermediate plate is made of metal.

14. 3. The LED lighting device according to claim 2, wherein at least one of the upper surface and the lower surface of the intermediate plate is provided with an auxiliary positioning portion for determining a joining position between the intermediate plate and the printed circuit board or a joining position between the intermediate plate and a heat sink.

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