Light emitting diode assembly with low thermal resistance

The present invention relates to a light emitting diode assembly with low thermal resistance, especially to a light emitting diode assembly with low thermal resistance equal to aerial thermal resistance.

For the package of the conventional light emitting diode (LED), the LED is generally fixed on a leadframe by binding paste and then wire bonded to corresponding pads on the leadframe. Afterward the LED is encapsulated by epoxy and the packaged LED is soldered to a printed circuit board.

The LED in above-mentioned package has performance and life inversely proportional to the junction temperature of the LED with respect to the package. Therefore, the performance of LED is influenced by the heat dissipation effect provided by the package.

It is the object of the present invention to provide a light emitting diode with low thermal resistance equal to aerial thermal resistance.

In one aspect of the present invention, the die of the LED is arranged on a heat-dissipating plate and has pads connected to a printed circuit board.

In another aspect of the present invention, the LED is mounted on a circuit board and a heat-dissipating substrate, whereby the thermal resistance of the LED assembly can be advantageously reduced to enhance the performance of the LED assembly.

The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which:

FIG. 1 shows the perspective view of the LED of the present invention;

FIG. 2 shows the sectional view of the LED of the present invention;

FIG. 3 shows the sectional view of the first preferred embodiment of the present invention;

FIG. 4 shows the sectional view of the second preferred embodiment of the present invention;

FIG. 5 shows the perspective view of the second preferred embodiment of the present invention;

FIG. 6 shows the sectional view of the LED of the second preferred embodiment of the present invention; and

FIG. 7 shows the sectional view of the third preferred embodiment of the present invention.

With reference now to FIGS. 1 and 2, the present invention provides a light emitting diode assembly with low thermal resistance. The light emitting diode assembly comprises an LED 1 , a circuit board 2 and a heat-dissipating substrate 3 .

The LED 1 is provided with a heat-dissipating plate 10 with a recess 11 .

The LED 1 has a die 12 bound within the recess 11 and the die 12 has pads (not shown) wire bonded to a printed circuit board 13 . Moreover, a protective encapsulation 14 is formed atop the die 12 .

As shown in FIGS. 1 to 3 , the printed circuit board 13 has copper trace 15 thereon and the copper trace 15 can be connected to the circuit board 2 and the heat-dissipating substrate 3 . Therefore, the heat generated by the die 12 can be dissipated out through the heat-dissipating plate 10 and the heat-dissipating substrate 3 . The heat-dissipating plate 10 and the heat-dissipating substrate 3 provide a large heat-dissipating surface to the die 12 , thus reducing the thermal resistance of the LED assembly.

FIG. 4 shows the sectional view of the second preferred embodiment of the present invention. The printed circuit board 13 is connected to the circuit board 2 through the copper trace 15 and the heat-dissipating plate 10 is directly in contact with the heat-dissipating substrate 3 on bottom thereof. The thermal resistance of the LED assembly can be advantageously reduced to enhance the performance of the LED assembly.

As shown in FIGS. 5 to 7 , the printed circuit board 13 of the LED assembly is connected to the circuit board 2 and the heat-dissipating substrate 3 through a plurality of pins 16 or connector (not shown). The thermal resistance of the LED assembly can be advantageously reduced to enhance the performance of the LED assembly.

As shown in FIG. 7, the circuit board 2 and the heat-dissipating substrate 3 have a plurality of via holes 4 therein, through which the pins 16 pass and are solder on distal ends thereof. The thermal resistance of the LED assembly can be advantageously reduced to enhance the performance of the LED assembly.

As can be seen from above description, the thermal resistance of the LED assembly can be advantageously reduced and the LED assembly can be applied to illumination utility, traffic sign and warning devices.

Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have suggested in the foregoing description, and other will occur to those of ordinary skill in the art. For example, the printed circuit board and circuit board can be rigid circuit board, flexible circuit board, metal frame or circuit trace on a metal plate. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.