Under normal circumstances, LED light-emitting wavelength with temperature change for the 0.2-0.3nm / ℃, spectral width increases, the impact of color brightness. In addition, when positive current flows through the pn junction, fever, loss of end zone so that have a temperature rise, at room temperature near the temperature rise 1 ℃, LED luminous intensity of a corresponding decrease of about 1%, cooling package; when maintaining color purity and luminous intensity is very important, in the past, the use of its drive to reduce the current approach to reduce the junction temperature, the majority of LED drive current limit of about 20mA. However, LED light output increases with increasing current, at present, a lot of power type LED drive current can reach 70mA, 100mA or 1A level, the need to improve the package structure, a new design LED package and low thermal resistance package structure and technology, to improve the thermal characteristics. For example, the use of large-area flip-chip structure, thermal properties of a good selection of silver plastic, metal stents increase the surface area of the silicon carrier solder bump directly installed in the upper heat sink method. In addition, in the application design, PCB circuit board, such as the thermal design, thermal performance is also very important.
Into the 21st century, LED-based high-performance, ultra-high brightness, and the continuous development of innovative panchromatic, red, orange LED luminous efficiency has reached 100Im / W, green LED for the 501m / W, the luminous flux LED alone also reached tens of Im. LED chip and package is no longer along the Gong traditional design and manufacture production patterns, increasing the chip's light output, the R & D is not limited to material changes in the number of impurities, lattice defects and dislocation to improve internal efficiency
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