The LED package is: bracket package, chip package, module package, these packaging methods are common and commonly used.
First, conventional existing packaging methods and application fields
The bracket package is the earliest used to produce a single LED device. This is our common lead-type LED (including piranha package), which is suitable for instrument indicator lights, urban lighting projects, advertising screens, barrier pipes, traffic Indicator lights, and some products and fields that are commonly used in China.
SMD package (SMD) is a leadless package, small and thin, very suitable for keyboard display illumination of mobile phones, backlighting of TV sets, and electronic products that require illumination or indication. In recent years, patch packages have been large. Dimensions and high power development, three or four LED chips in one chip can be used to assemble lighting products. The module package is also a multi-chip package, which packages dozens or hundreds of LED chips on a small or high package density on an aluminum oxide or aluminum nitride substrate, and the internal connection is a hybrid type, that is, There are multiple chips in series and several parallels. This package is mainly to expand the power and use it as a lighting product. Due to the high density of the package, the module package generates a large amount of heat during application, and heat dissipation is the primary problem to solve the application. The devices produced by the above packaging method have a common feature for the production of lighting fixtures: the number of thermal resistance is large, it is difficult to produce high-quality lighting fixtures, and the connection processing requirements between the module itself and the heat sink are relatively high. . At present, all the packaging methods are to mix the yellow phosphor (YAG) and the epoxy resin in different ratios, directly point to the blue LED chip, and then heat and solidify. The advantage of this common practice is that it saves materials. The disadvantage is that it is not conducive to heat dissipation and the phosphor will also age. Because both epoxy and phosphor are not heat-conducting materials, and wrapping the entire chip will affect heat dissipation. This approach is obviously not the best solution for the manufacture of LED lighting fixtures.
At present, high-power chips produced abroad, white light chips of 0.5 watts or more are coated with a uniform layer of YAG phosphor powder on the blue chip, and the appearance is a yellow cube (except for the two gold used for welding). The pad has no phosphor. This method can improve the light efficiency compared with the conventional methods. Therefore, it is widely used in foreign countries.) It is only necessary to solder the white chip to the designed circuit board during packaging, and the coating is omitted. The process of phosphors. It has brought convenience to the lighting manufacturers, but the current domestic production chip suppliers can not mass produce such LED white light chips.
China is an early country to develop LED street lamps. It is also good for domestic use. The reason is that the country attaches importance to the "low-carbon economy." In 2009, China implemented ten-city LED street lights. Many cities have experimental sections to test LED street lights. Feasibility, China is a breakthrough in the application of street lamps, while foreign countries ( Osram , Nichia, Samsung and other companies) are based on indoor lighting as a breakthrough, who is more advantageous in these two routes, has not yet seen. As far as China is concerned, LED lighting is the application direction, which is caused by the national conditions. The reason is that China's national income is low, and the cost of LED indoor lighting is high, and the people can't accept it. The use of LED street lights is the government's silver, LED street lamp manufacturers are fancy this. In fact, the working conditions of LED street lamps are more demanding and more demanding than indoor LED lighting fixtures. If quality can be achieved (heat dissipation, service life, color rendering, reliability, etc.), then it is easier to do indoor LED lighting. It is. At present, foreign LED giants are launching hundreds of models or even thousands of LED indoor lighting fixtures. The price ranges from 20 to 75 US dollars, and the power ranges from a few watts to 20 watts. But the packaging methods they used were all mentioned above. The only Philips company that applied phosphors to LED shades was named one of the most innovative LED lighting products of 2009.
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