Light emitting diode lighting module and method for making the same

A method for making a light emitting diode lighting module includes steps of: (a) packaging a plurality of light emitting diode dies respectively on a plurality of die-mounting parts of a metal lead frame to form a plurality of light emitting diodes, respectively; and (b) cutting off supporting parts of the lead frame so as to form a connecting structure through which the light emitting diodes are connected to each other in one of serial, parallel, and serial-and-parallel connecting manners.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese application no. 097108677, filed on Mar. 12, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a light emitting diode lighting module and a method for making the same, more particularly to a light emitting diode lighting module including a conductive connecting structure of a punched metal sheet, through which a plurality of light emitting diodes are packaged and connected to each other in one of serial, parallel, and serial-and-parallel connecting manners.

2. Description of the Related Art

Referring toFIG. 1, a conventional light emitting diode lighting module (hereinafter referred as LED lighting module)1is shown to include a printed circuit board12(or a ceramic board) with conductive traces121, a heat sink13connected to the printed circuit board12, and a plurality of light emitting diode packages10(hereinafter referred as LED package) soldered to and arranged on the printed circuit board12so as to be connected to each other in a serial or parallel connecting manner through the conductive traces121. The LED packages10can be formed using any well-known method. For example, the LED packages10can be formed by attaching light emitting diode dies (not shown) to a lead frame (not shown) to form an assembly (not shown), followed by enclosing each of the light emitting diode dies using an encapsulant or lens (not shown).

However, the steps of arranging and soldering the LED packages10onto the printed circuit board12result in a decrease in the productivity of the LED lighting module1. Besides, the presence of the printed circuit board12between the LED packages10and the heat sink13will reduce the thermal dissipation of the LED packages10when the LED lighting module1is turned on, and thus, will shorten the service life of the LED packages10.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a method for making a light emitting diode (LED) lighting module that can overcome the aforesaid drawbacks associated with the prior art.

Another object of the present invention is to provide a light emitting diode (LED) lighting module that dispenses with the need for a printed circuit board.

According to one aspect of the present invention, there is provided a method for making a light emitting diode (LED) lighting module, comprising: (a) packaging a plurality of light emitting diode dies respectively on a plurality of die-mounting parts of a metal lead frame to form a plurality of light emitting diodes, respectively; and (b) cutting off supporting parts of the lead frame so as to form a connecting structure through which the light emitting diodes are connected to each other in one of serial, parallel, and serial-and-parallel connecting manners.

According to another aspect of the present invention, there is provided a light emitting diode lighting module comprising: a punched metal sheet having a conductive connecting structure; and a plurality of light emitting diode, each of which includes a light emitting diode die packaged on the punched metal sheet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 2 and 3, the LED lighting module200of the first preferred embodiment of this invention is shown to include: a conductive connecting structure2of a punched metal sheet, and a plurality of light emitting diodes (hereinafter referred as LEDs)3. The connecting structure2is formed from a metal lead frame used for packaging a plurality of light emitting diode dies (not shown, hereinafter referred as LED dies) thereon. The LEDs3are formed by packaging the LED dies therein using any well-known method, and are connected to each other in one of serial, parallel, and serial-and-parallel connecting manners through the connecting structure2. It is noted that the printed circuit board12employed in the conventional LED lighting module1is dispensed with in the present invention, and thus, the requirement of arranging and soldering the LED packages10onto the printed circuit board12in the conventional LED lighting module1ofFIG. 1is eliminated in this invention.

In this preferred embodiment, the connecting structure2includes a plurality of die-mounting parts (not shown) for mounting LED dies thereon and for electrical connection, parallel first and second rails21,22, a plurality of first leads25connected to and disposed along the length of the first rail21, and a plurality of second leads26connected to and disposed along the length of the second rail22. Each of the LEDs3is electrically connected to an adjacent pair of the first and second leads25,26and is packaged on a respective die mounting part.

Preferably, the LED lighting module200further includes a heat sink5connected to the bottom of the LEDs3. The heat sink5includes a thermal conductive layer51and a mass metal part52. Each of the LED dies of the LEDs3is mounted on a thermal conductive pillar31which can be a material made from metals, such as, Cu, Al, Fe, or their alloys. Each of the pillars31protrudes from the bottom of a respective LED3. When the LED lighting module200is turned on, the heat generated from each of the LED dies of the LEDs3can be dissipated to the thermal conductive layer51and the mass metal part52of the heat sink5through the thermal conductive pillar31thereof (seeFIG. 2).

Preferably, the mass metal part52is made from aluminum or copper. In other embodiments, the thermal conductive layer51can be a thermal conductive glue or a thermal conductive film, and preferably provides electrical insulation.

Moreover, the connecting structure2further has upper and lower sides27,28. The LED lighting module200further includes an upper electric insulator plate4disposed on the upper side27of the conductive connecting structure2and formed with a plurality of through-holes41as shown inFIG. 5for extension of the LEDs3therethrough (seeFIGS. 2 and 5).

As shown inFIG. 2, the LED lighting module200further includes a lower electric insulator plate7attached to the lower side28of the connecting structure2between the conductive connecting structure2and the heat sink5. The lower electric insulator plate7is formed with a plurality of through-holes71, as shown inFIG. 5, for extension of the thermal conductive pillar31of each of the LEDs3therethrough (seeFIGS. 2 and 5). The presence of the upper and lower insulator plates4,7not only prevents the connecting structure2from short circuit, but also enhances the structural stability of the connecting structure2. The upper and lower insulator plates4,7can be made from any conventional electric insulator materials.

Preferably, the LED lighting module200further includes a plurality of fasteners6for locking the conductive connecting structure2, the LEDs3, the upper and lower insulator plates4,7and the heat sink5together. As shown inFIGS. 2,5and6, the upper and lower insulator plates4,7have upper and lower screw holes42,72, respectively, for extension of the fasteners6(for example, screws) therethrough. It should be noted that the upper insulator plate4used in the present invention is preferably slightly deformable upon tightening the fasteners6to press the pillars31of the LEDs3against the heat sink5. Since the LEDs3in the LED lighting module200are fixed by the fasteners6, not by soldering, and since the pillars31of the LEDs3are pressed against the heat sink5, the thermal conductivity between the LEDs3and the heat sink5can be greatly improved. As such, the efficiency of the heat dissipation of the LED lighting module200is better than that of the prior art.

FIG. 7illustrates the second preferred embodiment of the LED lighting module200′ according to this invention. The second preferred embodiment differs from the previous embodiment in that only the upper insulator plate4is attached to the upper side27of the connecting structure2and that the lower insulator plate7is dispensed therewith.

The method for making the LED lighting module200of the first preferred embodiment includes the following steps:

(a) packaging a plurality of LED dies (not shown) respectively on a plurality of die-mounting parts of a metal lead frame201to form a plurality of LEDs3on the lead frame201, respectively, using any well-known LED packaging method (seeFIG. 4);

(b) cutting off supporting parts23,24of the lead frame201so as to form the connecting structure2(seeFIGS. 3 and 4) through which the LEDs3are connected to each other in one of serial, parallel, and serial-and-parallel connecting manners;

(c) covering the upper and lower sides27,28of the connecting structure2using the upper and lower insulator plates4,7, respectively, after step (b) (seeFIGS. 2 and 5);

(d) attaching the LEDs3to the heat sink5after step (c) (seeFIG. 2); and

(e) locking the connecting structure2, the LEDs3the upper and lower insulator plates4,7, and the heat sink5together using the fasteners6(seeFIG. 2).

As shown inFIGS. 3 and 4, in the first preferred embodiment, prior to the cutting operation in step (b), the conductive lead frame201includes the die-mounting parts, the first and second rails21,22, the first leads25, the second leads26, and the supporting parts20interconnecting and disposed along the lengths of the first and second rails21,22. Each of the supporting parts20has latitudinal ribs23and longitudinal ribs24, and functions to support the LEDs3before the cutting operation.

By forming the connecting structure2from the lead frame201to interconnect the LEDs3in the method for making the LED lighting module200,200′ of this invention, the need for a printed circuit board is dispensed with, and thus, the aforesaid drawbacks associated with the prior art can be eliminated. Therefore, a light emitting diode lighting module having a longer service life and higher thermal conduction efficiency can be achieved by the present invention.