1.  Field of the Invention
The invention relates to a frame structure for light emitting diodes, particularly to the frame structure having a large cooling area to enhance overall cooling efficiency. 
2.  Description of the Related Art
LED, light emitting diode, is a semiconductor solid light-emitting device which uses a solid semiconductor chip as a light emitting material.  Due to the advantages of high energy-saving, long life and environmental protection, LED applications are more and more widely.  LED has environmental protection and energy saving features considered as a replacement of traditional light bulbs as the light source lighting.  The volume of LED is quite small, so LED frames are required in most of the production process for providing leads to connect the LED chip. 
The US Patent Pub.  No.  2010/0001306 as shown in FIG.  1 discloses a light emitting diode package 100, comprising a mold 102 with an opening portion 101, a plurality of lead frames 103, 104, 105 extending from an inside of the opening portion 101 to an outside of the mold 102 and a cavity 106 having a bottom exposed at a bottom of the mold 102 to increase cooling effect.  An angle θ1 of an inner wall of the opening portion 101 is smaller than an angle θ2 of an inner wall of the cavity 106.  Hence, the reflected light passing through the opening portion 101 is increased and thus the luminous height cannot be increased. 
A conventional frame structure 110 for the light emitting diodes as shown in FIG.  2A has features similar with the frame 100 as shown in FIG.  1, comprising a mold 112 with an opening portion 111, a plurality of lead frames 113, 114, 115 and a cavity 116.  However, the cavity 116 has a deeper depth d1 and thus a part of light is covered, having poor light-emitting efficiency; the cavity 116 is thin and thus it is easy to be broken, reducing reliability. 
The Taiwan Utility Model No.  M376909 applied by Fu Sheng Industrial Company discloses a frame structure 120 for the light emitting diode to improve the conventional problems.  The cavity 126 has a highest horizontal position lower than horizontal position of lead frames 123, 124 extending from a mold 122; that is, h>H. The cavity 126 is arranged in the mold 122 to decrease the depth d2 of the cavity 126 to maintain the thickness and structural strength. 
The Taiwan Utility Model No.  M408793 applied by Honhai Precision Industry Company discloses a light emitting diode lead frame 130, including a base 132 defined a top recess 131 and a lower recess 137, a plurality of metal frame 133, 134, 135 partially embedded in the base 132 and a chip bearing stand 136 for bearing the chips.  The top recess 131 and the lower recess 137 include an inclined inner wall.  A lighting area of a top of the top recess 131 is from 5.5 to 6.5 times of a bottom of the lower recess 137.  An angle B1 defined between two opposed walls of the top recess 131 is larger than another angle B2 defined between corresponding two opposed walls of the lower recess 137.  Thus, the reflected light from the wall of the top recess 131 is decreased to enhance the light-emitting efficiency. 
Based on the conventional features disclosed, according to the amount of wattage of the LED chip, the LED frame is molded and stamped in response to the cooling requirements of the LEDs.  That is, a smaller wattage LED chip has a smaller size of specification of LED frame referring to a small cooling area.  Conversely, a larger wattage LED chip has a larger size of specification of LED frame referring to a larger cooling area.  If a large wattage LED chip has a small size of specification of LED frame, the LED chip will be overheating, resulting poor light-emitting efficiency of light difference.  Therefore, there is room for improvement.