Package and heat dissipation of High Power LED,also has the relationship between junction temperature and LED color. Generally under normal light color is most pure, junction temperature will result in increased or decreased light color drift. Different wavelengths of light
has different the temperature sensitivity。The least sensitive to the highest sensitivity green light, The blue lights has bad sensitivity。
In any case, color drift will make the color temperature is not stable, affect the optical properties of white LED.The structure and principle of High-power LED heat dissipation Package LED Chip heat by conduction to the heat sink, heat sink through the air convection or outward radiation. In the high power LED cooling channel, MCPCB (meta1 core printed circuit boards) is connected with the internal and external cooling channel, at least the following functions:
1) Radiating channel of High Power LED chip;
2) electric LED chip connection;
3) The physical support of LED chip. Substrate materials for high power LED must have electrical insulation resistance, high stability, high thermal conductivity。 A few metals or alloys can meet the high thermal conductivity and low expansion coefficient requirements, To assume for electrical insulation, need to be coated polymer film (rarely have high thermal conductivity) or the deposition of a layer of ceramic film. Ceramic material of difficult processing and high cost, some semiconductor material physical parameters can well meet the requirements of the same substrate material, high cost, they are unlikely to be used for general lighting of the LED, but you can use a small as carrying LED Submount (one level heat sink), insulation function, attached to the heat sink (two level heat sink)。Power LED LumlledS as flip mode, with the silicon chip as the heat sink. Provide electrostatic protection through the zener diode of integrated in the silicon heat sink, this design can reduce the mismatch of thermal expansion coefficient of impact (silicon and sapphire substrate have similar thermal expansion coefficient). In addition, the silicon material and solder ball playing stress absorber, in order to further relieve the thermal expansion effect. In the silicon carrier adhesive solder ball makes the LED chip closely with silicon carrier joined together, and then the line connected to the lead frame.