(1) Field of the Invention
This invention relates to a light emitting diode (LED) package, and more particularly relates to a multi-chip LED package.
(2) Description of the Prior Art
Light emitting diode LED) is a small-sized cold-light solid-state lighting capable of transforming electric power into optical power with high efficiency. The LED is mainly composed of a semiconductor p-n junction structure. When a potential is applied to the p-n junction structure, electrons and holes are driven by the potential toward the junction surface and combined to release photons.
It is a typical method to use conductive glue, such as silver conductive adhesion, to fix the LED chip 12 and electrically connect the LED chip 12 to the wiring pattern 17 as shown in
In order to prevent the conductive paste layers 26 from being overlapped, a typical method is to increase the interval between neighboring LED chips 22. However, this method increases the size of the LED package.
Accordingly, it is an important issue for the LED packaging industry to provide a multi-chip LED package capable of preventing the unwanted influence due to the flowable conductive paste layers when using conductive glue to fix LED chips.
It is an object of the present invention to preventing the unpredictable bad influence toward circuit design for a multi-chip LED package because of the flowing of conductive glue.
A multi-chip light emitting diode (LED) package is provided in the present invention. The multi-chip LED package has a plurality of LED chips and a substrate. The substrate has a plurality of conductive patterns formed thereon. Each of the LED chips are assembled on the respected conductive pattern and electrically connected to the respected conductive pattern. The LED chips are connected in serial through the conductive patterns.
In an embodiment of the present invention, the substrate has at least two hollow areas, and each hollow area has at least two LED chips assembled therein and connected in parallel.
In an embodiment of the present invention, the substrate has at least two hollow areas, and each of the hollow areas has only one LED chip assembled therein.
The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which:
As a preferred embodiment, the board 120 may be formed of high thermal-conductivity metal, such as aluminum and etc., and the substrate 160 may be formed of semiconductor, such as silicon and etc. The substrate 160 has at least two hollow areas 162 formed thereon (four hollow areas 162 are shown in this figure). The hollow areas 162 are square in shape and evenly arranged on the substrate 160. The LED chips 140a,140b are assembled in the hollow areas 162.
The hollow area 162 has a conductive pattern 170 formed on a bottom surface thereof. The plurality of conductive paste layers 180 are formed on the bottom surface of the hollow areas 160 respectively for fixing respected LED chips 140a,140b. It is noted that the LED chip 140a,140b may be fixed on the conductive pattern 170 by eutectic bonding or using solder balls or gold balls if needed. The negative electrode of the LED chips 140a, 140b are electrically connected to the respected conductive pattern 170 on the bottom surface of the hollow area 162 by using the respected conductive paste layer 180 so as to have the LED chips 140a,140b flip-chip assembled on the substrate 160. The passivation layer 190 is deposited on the substrate and filled into the hollow areas 162 to prevent the LED chips 140a,140b from the intrusion of environmental particles and moisture.
Among the plurality of LED chips 140a,104b of the multi-chip LED package 100, the positive electrode of the LED chip 140a is electrically connected to a high level end 152 by using a wire 150, and the positive electrodes of the other LED chips 140b are electrically connected to the conductive patterns 170 in the neighboring hollow area 162 by using wires 150. Therefore, the LED chips 140a,140b located in the different hollow areas 162 are connected in serial. In addition, the conductive pattern 170 without connecting to the positive electrode of the LED chips 140a,140b (or the conductive pattern 170 in the hollow area 162 near the right upper corner of
Referring to
It is noted that the substrate 160 and the hollow areas 162 on the substrate are square in shape. However, the main idea of the present invention focuses on preventing the uncontrollable flowing of the conductive paste layer 180 by the formation of hollow areas 162. The shape of the substrate 160 and the hollow areas 162 should not be a limitation to the present invention. Thus, the substrate 160 and the hollow areas 162 may have a different shape, such as circular or rectangular according to the need.
The first hollow area 262 and the second hollow area 264 are rectangular in shape and evenly arranged on the substrate 260. Independent conductive patterns 270 are formed on the bottom surfaces of the first hollow area 262 and the second hollow area 264 respectively. Each of the hollow areas 262, 264 has two LED chips 240a,240b assembled therein. The plurality of the conductive paste layers 280 are pasted on the bottom surface of the first hollow area 262 and the second hollow area 264 for fixing the LED chips 240a,240b, respectively. The conductively paste layers 280 are also capable to electrically connect the negative electrode of the LED chips 240a,240b to the respected conductive patterns 270. The passivation layer 290 is deposited on the substrate 260 and filled into the hollow areas 262,264 to prevent the LED chips 240a,240b from the intrusion of the environment particles and moisture,
It is noted that the negative electrodes of the LED chips 240a,240b in each hollow areas 262,264 are electrically connected to the same conductive patterns 270 through the conductive paste layers 280 respectively. In addition, the positive electrodes of the two LED chips 240a assembled in the first hollow area 262 are electrically connected to a high level end 252 by using wires 250, the positive electrodes of the two LED chips 240b assembled in the second hollow area 264 are electrically connected to the conductive pattern 270 in the first hollow area 262 by using wires 250, and the negative electrodes of the two LED chips 240b are electrically connected to a low level end by using wires 250. That is, the LED chips 240a in the first hollow area 262 are connected in parallel, the LED chips 240b in the second hollow area 264 are connected in parallel, and the LED chip 240a in the first hollow area 262 is connected to the LED chip 240b in the second hollow area 264 in serial. The circuit diagram of the LED chips 240a,240b is shown in
In the present embodiment, the flowing of the conductive paste layer 280 pasted on the bottom of the hollow areas 262, 264 respectively are restricted by the sidewalls of the hollow areas 262,264. That is, because the uncontrollable flowing of the conductive paste layer 280 is restricted in the hollow area 262, 264, the negative electrodes of the LED chip 240a in the first hollow area 262 and that of the LED chips 240b in the second hollow area 264 would be perfectly isolated to prevent the happening of short circuit.
In addition, the multi-chip LED package 100 in
In the traditional multi-chip LED package 20 of
In addition, it is a traditional method to increase the interval between neighboring LED chips for preventing the unwanted influence of the flowing of the conductive paste layer. However, this method increases the size of the whole package and badly influences the focusing of illumination of the LED chips. In contrast, because the multi-chip LED package 100,200 of the present invention has hollow areas 162,164 formed on the substrate 160 for restricting the flowing of the conductive paste layers 180,280, the distance between neighboring hollow areas 162,164 can be reduced. Thus, the multi-chip LED package 100,200 in the present invention may prevent the problems of size increasing and the difficulty about illumination focusing of LED chips.
While the preferred embodiments of the present invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the present invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the present invention.
Number | Date | Country | Kind |
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96128027 | Jul 2007 | TW | national |