TECHNICAL FIELD

[0001] This application relates generally to light emitting diodes (LEDs), and more particularly to efficient heat dissipation in LEDs.

BACKGROUND

[0002] Light emitting diodes (LEDs) are increasingly used these days to replace conventional lighting devices. Because of their small size, low power consumption, and long life, LEDs are applied to various display applications. These lighting devices, however, have one drawback - they generate large amounts of heat, and if the heat is not dissipated effectively, the efficiency and the lifetime of LEDs may be limited.

[0003] Generally, LEDs are encapsulated in a transparent resin and mounted on a printed circuit board (PCB). The resin, however, is a poor thermal conductor, preventing heat dissipation from the LED's front surface. Therefore, heat is typically dissipated from the non- emitting side of the LED, which is welded to one side of the PCB. In general, PCBs include two metal layers and an insulating layer sandwiched between the metal layers. A heat sink is mounted on the other side of the PCB. Further, LEDs may include a metal plate such as a heat slug attached above the LED that improves heat dissipation. For these structures, the cooling path is defined as - LED heat slug - PCB's first metal layer - PCB's insulting layer - PCB's second metal layer - heat sink. Often, the insulating layer prevents effective heat dissipation from the PCB to the heat sink leading to high LED junction temperatures.

[0004] Thus, it would be desirable to provide an efficient heat dissipation path from the LED to the heat sink for maintaining a low LED junction temperature and ensuring efficient LED function.

SUMMARY

[0005] In accordance with an embodiment of the present disclosure a thermal management system for light emitting diodes (LEDs) is disclosed. The system includes a printed circuit board (PCB) having one or more apertures, a light emitting diode (LED) mounted on PCB's first side, a heat sink mounted on PCB's second side, and one or more inserts, having a first end and a second end, implanted in the one or more apertures, wherein the first end is connected to the LED and the second end is connected to the heat sink.

[0006] According to another embodiment a LED assembly is disclosed. The LED assembly includes a PCB having one or more apertures, one or more LEDs mounted on PCB's first side, a heat sink mounted on PCB's second side, one or more inserts, implanted in the one or more apertures, having a first end and a second end, wherein the first end is connected to the one or more LEDs and the second end is connected to the heat sink, and a thermally conductive member disposed between the PCB and the heat sink. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings illustrate one or more embodiments and/or aspects of the disclosure and, together with the written description, serve to explain the principles of the disclosure. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment. The drawings are illustrative in nature and are not necessarily drawn to scale.

[0008] FIG. 1 is a side view of an exemplary light emitting diode (LED) structure according to an embodiment of the present disclosure.

[0009] FIG. 2 is a front view of an exemplary LED assembly according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

[0010] To promote an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will, nevertheless, be understood that no limitation of the scope of the disclosure is thereby intended; any alterations and further modifications of the described or illustrated embodiments and any further applications of the principles of the disclosure as illustrated therein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. All limitations of scope should be determined in accordance with and as expressed in the claims.

Overview [0011] The present disclosure provides a thermal management system for light emitting diodes (LEDs). Generally, heat sinks are employed to dissipate the heat generated by LEDs in high power applications. The thermal management system of the present disclosure includes a printed circuit board (PCB) having one or more apertures. A light emitting diode (LED) is mounted on one side of the PCB, and a heat sink is mounted on the other side, opposite to the LED. Moreover, one or more heat conductive inserts are embedded in the apertures to connect the LED with the heat sink. Because the inserts directly connect the LED to the heat sink, the PCB is removed from the heat path. With the insulative PCB layer out of the heat path, the generated heat can be efficiently transferred to the heat sink, thereby lowering the LED junction temperature.

Exemplary embodiments

[0012] FIG. 1 is the side view of an exemplary LED structure 100. In the exemplary

LED structure 100, an LED 102 is mounted on a first side of a PCB 104. A heat sink 106 is disposed on a second side of the PCB 104 to dissipate the heat produced by the LED 102. The PCB 104 includes an aperture 108 to accommodate an insert 110. One end of the insert 110 is welded to an LED heat slug 112 and the other end to the heat sink 106. Thus, the insert 110 directly connects the LED heat slug 112 with the heat sink 106, bypassing the PCB 104, resulting in direct and efficient heat transfer from the LED 102 to the heat sink 106. This configuration provides a direct thermal path between the LED and the heat sink and reduces heat transferred to the PCB 104 and other components mounted on the PCB 104.

Alternatively, the PCB may include multiple apertures and inserts to connect the LED 102 with the heat sink 106.

[0013] In the embodiment shown in FIG. 1, the aperture 108 and the embedded insert 110 are placed directly above the LED 102. Alternatively, the PCB 104 may include the aperture 108 at some other location, which is not directly above the LED 102. In such a scenario, the insert 110 may be a flexible structure, such as a conductive wire, that connects the LED 102 to the heat sink 106 through the aperture 108.

[0014] Generally, the aperture's 108 geometry and dimension correspond with the insert's 110 geometry and dimension. For example, the insert 110 may be substantially cylindrical in shape and the aperture 108 may have a circular cross-section. Also, the aperture's dimension may be substantially equal to or greater than the insert's cross-sectional dimensions. It will be understood by those skilled in the art that the aperture 108 and the insert 110 may have any suitable geometry or dimension without departing from the scope of the present disclosure. For example, the insert 110 may be shaped as a cuboid and the aperture 108 may have a generally rectangular cross-section.

[0015] Moreover, the insert 110 may be formed of any thermally conductive material, such as copper, but it will be understood that any suitable thermal conductive material may be utilized just as easily without departing from the scope of the present disclosure. For example, the insert 110 may be formed from aluminum.

[0016] In addition to the insert 110, a thermally conductive member, such as conductive plate 114 may be placed between the PCB 104 and the heat sink 106 for improving heat dissipation between the LED 102 and the heat sink 106. The thermally conductive plate 114 includes one or more apertures to allow the insert 110 to pass through.

[0017] In an alternate embodiment, the conductive plate 114 may not include apertures. In this embodiment, one end of the insert 110 may be connected to the heat slug 112 and the other end may be connected to the conductive plate 114. The conductive plate 114 is, in turn, connected to the heat sink 106. The LED cooling path for this structure may be defined as LED heat slug - insert - thermally conductive member - heat sink.

[0018] The thermally conductive plate 114 may be formed of any suitable thermally conductive material such as copper or aluminum. Further, the thermally conductive plate 114 and the heat sink 106 may be coated with an appropriate amount of thermal grease to improve thermal conductivity.

[0019] Permanent or detachable connecting means may be utilized to attach the conductive plate 114 to the heat sink 106 and the PCB 104. Detachable connectors may include screws, snap fits, nuts and bolts, and so on. Other detachable connection techniques known in the art can just as easily be used without departing from the scope of the present disclosure. Permanent connections may include welding, molding, or gluing. Other methods for permanent connection may also be utilized.

[0020] As shown in FIG. 1, the heat sink 106 may include multiple fins to increase the surface area available for heat transfer to the atmosphere. Different fin types exist, and any one of these may be utilized here without departing from the scope of the present disclosure. For example, pin type, straight or flared fin type heat sinks may be employed. Alternatively, non-fin type heat sinks may also be incorporated. It will be understood that heat sink designs may vary, and any of the now known or future heat sinks may be utilized instead. Further, the heat sink 106 may be formed from any suitable material. Example materials may include, but are not limited to, aluminum, copper or any other highly conductive material.

[0021] Various methods may be used to increase heat transfer from the insert 110 to the heat sink 106. For example, the surface of the heat sink 106 in contact with the insert 110 may be highly polished to increase the surface area.

[0022] FIG. 1 illustrates the thermal management system for a single LED. This system may be extrapolated for a multiple LED lighting system. FIG. 2 is the front view of one such exemplary LED lighting system 200. In the exemplary LED lighting system 200, multiple LEDs 202 are mounted on a PCB's first side. A heat sink 206 is disposed on the PCB's second side for heat dissipation. The PCB 204 includes multiple apertures (not shown), above the LEDs, to accommodate inserts (not shown) corresponding to each LED 202. Further, a thermally conductive member 208 may be placed between the PCB 204 and the heat sink 206. This thermally conductive member 208 improves heat dissipation between the LED 202 and the heat sink 206. In one embodiment of the present disclosure, the thermally conductive member 208 includes multiple apertures to allow the inserts to pass through. Thus, the ends of the inserts are welded to the LED heat slugs (not shown) and the heat sink 206 resulting in efficient heat transfer. Alternatively, the ends of the inserts may be welded to the LED 202 and the thermally conductive member 208, resulting in heat transfer from the LED heat slugs to the thermally conductive member 208 and then from the thermally conductive member 208 to the heat sink 206. Further, multiple inserts may be employed to connect each individual LED 202 with the heat sink 206.

[0023] The specification has set out a number of specific exemplary embodiments, but those skilled in the art will understand that variations in these embodiments will naturally occur in the course of embodying the subject matter of the disclosure in specific

implementations and environments. It will further be understood that such variation and others as well, fall within the scope of the disclosure. Neither those possible variations nor the specific examples set above are set out to limit the scope of the disclosure. Rather, the scope of claimed invention is defined solely by the claims set out below.