TWI390761B - LED package - Google Patents

Description

LED package

This invention relates to light emitting diode packages and, more particularly, to light emitting diode packages using thermoelectric elements.

A light-emitting diode (hereinafter referred to as "LED") refers to a semiconductor device having a positive-negative junction structure in which a minority carrier (electron or hole) is implanted, and light is emitted via a composite of carriers. Various light sources can be constructed by modifying materials of synthetic semiconductors (eg, GaAs, AlGaAs, GaN, InGaN, and AlGaInP) to provide light having a plurality of colors. The brightness of the LED is proportional to the current applied to its luminescent wafer, and the current applied to the luminescent wafer is proportional to the amount of heat generated from the luminescent wafer. Therefore, a high current should be applied to increase the brightness of the LED. However, since the light-emitting wafer may be damaged by the heat generated therefrom, there is a problem that the current cannot be increased indefinitely. That is, as the current applied to the light-emitting wafer increases, the amount of heat generated therefrom also increases.

5 is a cross-sectional view of a conventional light emitting diode package including a substrate on which at least one light emitting wafer is mounted, and a pair of lead frames. The substrate is formed of an insulating resin and has a reflective portion formed to surround the light emitting wafer. The two electrodes of the luminescent wafer are connected to the respective frame via conductive wires. The lead frames are electrically isolated from each other.

In a conventional light emitting diode package constructed as described above, heat generated from the light emitting wafer is dissipated via the lead frame. However, there is a limit in the amount of heat dissipated only by the heat dissipation of the lead frame of the light emitting diode package. special In addition, for newly developed high power LED packages, heat conduction through the lead frame alone is not sufficient to dissipate heat. That is, if there is no appropriate heat dissipation structure in the light emitting diode package, the heat generated by the self-luminous wafer cannot be effectively dissipated, thereby causing a problem of shortening the service life of the light-emitting chip.

The present invention has been conceived to solve the above problems in the prior art. It is an object of the present invention to provide a light emitting diode package in which a thermoelectric element is used to effectively dissipate heat generated from a self-luminous wafer to the outside, thereby extending the life of the light emitting wafer and thereby improving the function of the light emitting diode. .

In order to achieve this object, the present invention provides a light emitting diode package including a thermoelectric element and at least one light emitting chip mounted on the thermoelectric element. Additionally, the present invention provides a light emitting diode package including a housing, a thermoelectric element coupled to the housing, and at least one luminescent wafer mounted on the thermoelectric element. The thermoelectric element may include a heat absorbing portion on which the light emitting wafer is mounted, a heat radiating portion parallel to the heat absorbing portion, and a plurality of thermoelectric semiconductors disposed between the heat absorbing portion and the heat radiating portion. A plurality of electrodes are formed on a top surface of the thermoelectric element, the electrodes are electrically coupled to the light emitting chip and the thermoelectric element, and the light emitting chip is mounted on at least one of the electrodes.

The light emitting diode package of the present invention may further comprise a reflective portion provided around the light emitting wafer.

The light emitting diode package of the present invention can further include a heat sink coupled to the thermoelectric element.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Detailed description. However, the invention is not limited to the embodiments, but may be constructed in various forms. These embodiments are provided for purposes of illustration only and a full understanding of the scope of the invention. Similar elements are denoted by like reference numerals throughout the drawings.

1 and 2 are views specifically illustrating the thermoelectric effect. As shown in FIG. 1, a semiconductor (for example, a semiconductor doped with an n-type impurity) is overlapped between the same metal, and one of the metals is connected to the positive electrode of the power source, and the other of the metal is connected to The negative electrode of the power supply. In this case, electrons in the n-type semiconductor move to one metal and then to another metal, resulting in a flow of current. As shown in FIG. 2, the charge carriers (ie, electrons) flowing from the metal to the n-type semiconductor are limited to those having an energy greater than the potential barrier (E _c -E _f )/e[J/C]. Therefore, only electrons having a sum of (E _c -E _f ) and having an average kinetic energy of electrons 3k _B T/2 at an absolute temperature T can flow into the n-type semiconductor region. Here, E _c is the energy level of the conduction band of the n-type semiconductor, E _f is the Fermi level of the n-type semiconductor, e is the number of charges of the electron, and K _B is the Boltzmann constant. In the interface between one of the metals and the n-type semiconductor, when the charge carriers move from one of the metals to the n-type semiconductor, the charge carrier loss E (=E _c -E _f +3k _B T/ 2[J])) Energy to be able to cool the metal. Conversely, in the other interface between the other of the metals and the n-type semiconductor, when the charge carriers move from the n-type semiconductor to the other of the metals, the charge carrier loss E (=E _c -E The energy of _f +3K _B T/2[J]) to cause an exothermic reaction in another metal. If the polarity of the applied voltage is switched, a reverse phenomenon occurs. Thus, heat can be transferred by electrical energy. In this way, the phenomenon of generating or absorbing heat in the portions of the two different metal connections when the current flows through the junction of the two different metals is called the Peltier effect.

The thermoelectric element used in the present invention is a Peltier element using a Peltier effect. Referring to Fig. 3, when direct current is applied to the n-type and p-type semiconductors, electrons having thermal energy absorbed from the surrounding environment move into the thermoelectric semiconductor at the negative charge contact points of the metal and the semiconductor, thereby causing an endothermic reaction. At the positive charge contact point, the electrons release thermal energy, thereby causing an exothermic reaction. The thermoelectric element is obtained by continuously combining elements each of which includes a metal and a thermoelectric semiconductor as described above, and can be constructed as illustrated in FIG. Referring to the drawings, a thermoelectric element for use in the present invention includes a heat absorbing portion, a heat radiating portion parallel to the heat absorbing portion, and a plurality of thermoelectric semiconductors disposed between the two portions. Here, when heat absorption by the endothermic reaction is provided in the LED package, heat dissipation of the light emitting diode can be further promoted. 6 and 7 are circuit diagrams showing internal circuits of a light emitting diode package in accordance with the present invention. A thermoelectric element is provided within the LED package to effectively dissipate heat generated by the self-illuminating wafer. In Fig. 6, two terminals are provided in such a manner that V _P and V _{LEDs are} combined into a single terminal, whereby a power source is simultaneously supplied to the light-emitting chip and the thermoelectric element. Alternatively, as shown in FIG. 7, three or four terminals are provided in a manner of separately constructing a V _P to be connected to the thermoelectric element. In this case, since the V _P for supplying power to the thermoelectric element is separated, the light-emitting chip and the thermoelectric element can be independently driven. Thereby, the efficiency of the thermoelectric element can be easily controlled by controlling the current in the external circuit.

Figure 8 is a perspective view of a light emitting diode package in accordance with a first embodiment of the present invention. In this embodiment, thermoelectric element 30 is combined with housing 35 in a typical LED package. Thereby, the thermoelectric element 30 is used as a direct dissipation generation A heat sink that self-illuminates the heat of the wafer. Figure 9 is a cross-sectional view of an LED package in accordance with this embodiment.

8 and 9, the light emitting diode package of the present invention includes one or more light emitting wafers 50 that emit light according to a voltage, an outer casing 35 made of a thermosetting resin and having predetermined through holes, and meshed with the outer casing 35. The thermoelectric element 30 in the through hole. Further, the light emitting diode package further includes: a lead frame 20 for inputting an external voltage on both sides of the outer casing 35, and an electric wire 60 for electrically connecting to the light emitting wafer 50. The thermoelectric element 30 is electrically insulated. For the electrical connection of the luminescent wafer 50, the electrode 40 is formed at a predetermined position on the top surface of the thermoelectric element 30, and the luminescent wafer 50 is mounted on the electrode 40. Preferably, the electrode 40 is fabricated and formed by a metallic material having excellent conductivity (e.g., copper or aluminum) and printing techniques. In this embodiment, the electrodes 40 are coated to facilitate electrical connection and mounting of the luminescent wafer 50. Alternatively, the luminescent wafer 50 can be directly mounted on the top surface of the thermoelectric element 30, and the two electrodes of each of the luminescent wafers can be connected to both sides of the illuminating diode package by a pair of wires 60. Lead frame 20.

Meanwhile, the wiring of the thermoelectric element 30 is not shown in FIGS. 8 and 9. However, referring to the circuit diagram of FIG. 6, this embodiment provides a light emitting diode package having two terminals, wherein the two electrodes of the thermoelectric element 30 are electrically connected to the lead frame 20 by additional wiring. This means that the V _P and the V _LED are connected to each other in common to supply the power source to the light-emitting chip 50 and the thermoelectric element 30 at the same time. Further, referring to the circuit diagram of FIG. 7, three or four lead frames 20 may be provided to independently drive the light-emitting wafer 50 and the thermoelectric elements 30.

The light emitting diode package further includes a reflective portion on the outer casing 35 15 and a lead frame 20 for increasing the brightness of light emitted from the light-emitting chip 50 and improving light concentration. The reflecting portion 15 is recessed in the form of an inverted truncated cone having an upper diameter at least larger than the lower diameter, and the inclined portion at the recess serves as a mirror for reflecting light emitted from the light emitting wafer 50. The reflective portion 15 should be electrically insulated from the lead frame 20 provided at the lower portion and should be composed of an insulating thermosetting resin. Further, a molded portion is formed on the light-emitting wafer 50 using an epoxy resin.

Figure 10 is a perspective view of a light emitting diode package in accordance with a second embodiment of the present invention. In this embodiment, the thermoelectric element 30 is formed by the substrate itself such that the thermoelectric element 30 functions as a heat sink that directly dissipates heat generated from the light-emitting wafer 50. Figure 11 is a cross-sectional view of the LED package.

Referring to Figures 10 and 11, the light emitting diode package of the present invention includes one or more light emitting wafers 50 that emit light according to a voltage, and a thermoelectric element 30 on which the light emitting wafer is mounted. The light emitting diode package further includes a lead frame 20 for inputting an external voltage on both sides of the top surface of the case 35, and an electric wire 60 for electrically connecting to the light emitting chip 50. Thermoelectric element 30 is electrically insulating. For the electrical connection of the luminescent wafer 50, the electrode 40 is formed at a predetermined position on the top surface of the thermoelectric element 30, and the luminescent wafer 50 is mounted on the electrode 40. Preferably, the electrode 40 is fabricated and formed by a metallic material having excellent conductivity (e.g., copper or aluminum) and printing techniques. In this embodiment, the electrodes 40 are coated to facilitate electrical connection and mounting of the luminescent wafer 50. Alternatively, the luminescent wafer 50 can be directly mounted on the top surface of the thermoelectric element 30, and the two electrodes of each of the luminescent wafers can be connected to both sides of the illuminating diode package by a pair of wires 60. Lead frame 20.

Meanwhile, the wiring of the thermoelectric element 30 is not shown in FIGS. 10 and 11. However, referring to the circuit diagram of FIG. 6, this embodiment provides a light emitting diode package having two terminals, wherein the two electrodes of the thermoelectric element 30 are electrically connected to the lead frame 20 by additional wiring. This means that the V _P and the V _LED are connected to each other in common to supply the power source to the light-emitting chip 50 and the thermoelectric element 30 at the same time. Further, referring to the circuit diagram of FIG. 7, three or four lead frames 20 may be provided to independently drive the light-emitting wafer 50 and the thermoelectric elements 30.

The light emitting diode package further includes a reflective portion 15 on the thermoelectric element 30, and a lead frame 20 for increasing the brightness of light emitted from the light emitting chip 50 and improving light concentration. The reflecting portion 15 is recessed in the form of an inverted truncated cone having an upper diameter at least larger than the lower diameter, and the inclined portion at the recess serves as a mirror for reflecting light emitted from the light emitting wafer 50. The reflective portion 15 should be electrically insulated from the lead frame 20 provided at the lower portion and should be composed of an insulating thermosetting resin. Further, a molded portion is formed on the light-emitting wafer 50 using an epoxy resin.

As described above, by using the endothermic reaction of the thermoelectric element, the thermoelectric element is used as a heat sink, so that the heat generated by the self-luminous wafer can be effectively dissipated to reduce the stress caused by the heat generated from the LED.

Furthermore, as described above, the heat generated by the self-illuminating wafer can be effectively dissipated by applying the thermoelectric element to the light emitting diode package. The external heat sink can be further combined into the light emitting diode package to more effectively improve heat dissipation efficiency.

According to the invention described above, there is provided a light emitting diode package using a thermoelectric element. Thus, it can be effectively generated from the inside of the package The heat of the optical wafer is dissipated to the outside without the need for additional external heat dissipating members.

Further, a reflective portion is provided outside the light-emitting chip to increase the brightness of the light-emitting diode, thereby improving the efficiency of the light-emitting diode.

The light emitting diode package of the present invention is not limited to the above embodiment, and can be applied in various forms.

For example, although the embodiment described above includes four light-emitting wafers, the number of light-emitting chips is not limited to four, and five or more light-emitting chips may be mounted on the thermoelectric elements.

15‧‧‧Reflection

20‧‧‧ lead frame

30‧‧‧Thermal components

35‧‧‧Shell

40‧‧‧Electrode

50‧‧‧Lighting chip

60‧‧‧Wire

The above and other objects, features and advantages of the present invention will become apparent from

Fig. 1 is a schematic view explaining the principle of a thermoelectric element.

Fig. 2 is a schematic view showing an exothermic and endothermic reaction according to the energy level of the thermoelectric element.

Figure 3 is a schematic diagram showing the basic connection of thermoelectric elements.

4 is a schematic view showing the internal structure of a thermoelectric element according to an embodiment of the present invention.

5 is a cross-sectional view of a conventional light emitting diode package.

6 and 7 are circuit diagrams showing internal circuits of a light emitting diode package in accordance with the present invention.

Figure 8 is a perspective view of a light emitting diode package in accordance with a first embodiment of the present invention.

Figure 9 is a cross-sectional view of a light emitting diode package in accordance with a first embodiment of the present invention.

Figure 10 is a perspective view of a light emitting diode package in accordance with a second embodiment of the present invention.

Figure 11 is a cross-sectional view of a light emitting diode package in accordance with a second embodiment of the present invention.

Claims (8)

A light emitting diode package comprising: a thermoelectric element; and at least one light emitting chip mounted on the thermoelectric element, wherein a plurality of electrodes are formed on a top surface of the thermoelectric element, the electrode and the light emitting chip and The thermoelectric element is electrically coupled, and the light emitting chip is mounted on at least one of the electrodes. A light emitting diode package comprising: a housing; a thermoelectric element coupled to the housing; and at least one light emitting chip mounted on the thermoelectric element, wherein a plurality of electrodes are formed on a top surface of the thermoelectric element, The electrode is electrically coupled to the light emitting chip and the thermoelectric element, and the light emitting chip is mounted on at least one of the electrodes. The light emitting diode package of claim 1 or 2, wherein the thermoelectric element and the at least one of the light emitting wafers are supplied with power via the same terminal. The light emitting diode package of claim 1 or 2, wherein the thermoelectric element and the at least one of the light emitting wafers are independently driven. The light emitting diode package of claim 1 or 2, wherein the thermoelectric element comprises a Peltier element. The light emitting diode package of claim 1 or 2, wherein the thermoelectric element comprises: a heat absorbing portion on which the light emitting wafer is mounted; a heat radiating portion parallel to the heat absorbing portion; and a plurality of thermoelectric semiconductors disposed between the heat absorbing portion and the heat radiating portion. The light emitting diode package of claim 1 or 2, further comprising a reflective portion surrounding the light emitting wafer. The light emitting diode package of claim 1 or 2, further comprising a heat sink coupled to the thermoelectric element.