LED display new high density level LED encapsulation, rounding

With rapid development of LED display technology, the point spacing are getting smaller, LED encapsulation from 3528, 2020, 1515, 1010, 0505, to a smaller size in order to satisfy the demands of high density, become the LED industry hot products. High-density LED with high pixel density and scanning ratio, high refresh rate and high gray level four development trend. High-density LED can be used to touch, 3-d, intelligent applications, such as cloud seeding control concept, broadening the application field of LED display. At present, the small distance between the LED display market potential is tremendous. LED display has no small spacing flat-fell seam, low energy consumption, long life and excellent display effect, with the improving of the photosynthetic efficiency and integrated control technology matures, the LED screen will gradually replace the original small spacing DLP, LCD, expanding the size of its market space. But little distance between the LED display screen display effect, high resolution on load, splicing gap the three bottlenecks restricting the development of LED display. At the same time, the high density LED display distance is more and more small, heat dissipation problems stand out, also seriously affect the color uniformity and screen life. In order to solve the problem of high density LED display heat dissipation, in this paper we put forward a new type of packaging, can effectively solve the difficult problems such as heat dissipation, pasted on. 1, traditional encapsulation mode display screen is in printed circuit board ( PCB） One side of the SMT driver integrated circuits ( IC) Mount the lamp body, the other side, through constant current lamp body emitting chip driver. Constant current chip layout is reasonable directly influence the screen display effect, thermal effect produced by the LED to normal luminescence properties; Color uniformity, in turn, affects the whole screen. In addition, the LED lamp body size miniaturization leads to surface patch encapsulation technology of SMT process and difficulty of repair. In addition to high density display pixel pitch is more and more small, constant current output chip foot also increases, heat dissipation problems highlighted become needs to solve the problem, bad heat dissipation will lead to screen body heat unevenly, and affect the display uniformity and life. LED packaging of 1515, 2020, 3528, light body, pin J or encapsulation mode L shape. The star of the 1010 and 0505 are using square flat no pin encapsulation ( QFN) 。 QFN is a kind of bonding pad size, volume is small, with plastic as the sealing material of the new type of surface-mount packaging technology. By the leakage and has a direct cooling channel lead frame of the solder heat release package chips, has good heat dissipation performance. At the same time, because the internal pins and bonding pad between the conductive path is shorter, so the self-inductance and encapsulate the body wiring resistance is very low, so can offer good performance, and overall small electromagnetic interference. But its weld fully at the bottom, the whole device removal, repair need for high-density LED display repair is difficult. 2, new way of packaging in order to solve the problem of traditional way encapsulation of heat dissipation and the two difficulties of repair, this paper puts forward a new way of packaging, can effectively solve these problems, and can greatly promote the reliability of the product, make it possible to have extremely high density pixels LED array. Law of development of LED technology is summed up that, can tolerance on smaller LED chip area larger current drive, and get better luminous flux and tropical characteristics, so as to get better performance. New packaging is a kind of based on ball grid array structure and chip level LED new packaging, are shown in figure 1 below. Constant current drive logic chip and LED wafer packaging together, construction mainly include seven parts: epoxy resin filling, LED, IC chip, wafer, support body interconnection layer and solder ball ( Or bumps, welding column) And the protective layer. Interconnection layer through the load with automatic welding, wire bonding and flip chip method to implement the chip and the solder ball ( Or bumps, welding column) Internal connection between, is a key part of encapsulated. LED life is closely related to heat dissipation, high temperature operation for a long time will accelerate the attenuation, reduce the service life. And as the temperature increases, the LED light color performance also has obvious changes, color offset, color distortion, further affect the quality of the LED display. The new packaging form, will use tin ball and cooling channel to assist cooling heat dissipation, and the best way to increase the heat dissipation is the use of heat dissipation tin ball. Heat dissipation tin ball is directly installed on the chip directly under the base board of tin ball, tin can borrow the ball directly upload heat on PCB, and to reduce the thermal resistance of the air. In order to make the heat to the ball more quickly, can use cooling channels through the substrate. The application of new packaging way to drive IC manufacturers and LED packaging manufacturer integrating resources, and that makes it possible to micro spacing LED display promotion. 3, the conclusion of this paper mainly introduces the LED display is a new type of high density level LED packaging format. LED the new packaging is the product of IC with lights, modular, assembly easier, more efficient. This new packaging format also can effectively improve the micro spacing LED heat dissipation problem, play an important role for the promotion of micro spacing LED display.