8 large-angle high-density small-pitch LED screen technology

With the rapid progress of LED display technology, LED display point spacing is getting smaller, now the market has introduced P1.4, P1.2 high-density LED display, and began to apply in the field of command control and video surveillance.

In the indoor monitoring large-screen DLP splicing and LCD splicing the two display technology occupy the market opportunity, although they have advantages, but there is a common problem, that is the display unit between the seams. High-density LED display with congenital advantages can be seamless stitching. The high-density display pixels are getting smaller, the resolution is getting higher, the display is clearer and more delicate. When displaying standard high-definition images, the resolution requirements can be fully met. If the high-density lamp price is getting lower, the high-density LED display will occupy a larger market in the field of indoor video surveillance.

High-density LED display with HD display, high refresh frequency, seamless splicing, good cooling system, easy disassembly and flexible features. With the increase of the pixel spacing, the LED mounting, assembling, splicing technology and structure are demanding more and more. In this paper, the process problems are discussed.

1, LED selection: P2 above the density of the display is generally used 1515, 2020, 3528 of the lamp, LED pin shape using J or L package. Side weld pin, weld area will have reflective, ink color effect is poor, it is bound to need to increase the mask to improve contrast. Further increase in density, L or J packaging can not meet the minimum electrical performance spacing requirements, the QFN package must be used. The Guoxing 1010 and 0505 of the crystal table are in this type of package.

Original QFN package Welding unique process, this process is characterized by no lateral weld pin, the welding zone without reflection, which makes the color rendering is very good. In addition, all-black integrated design compression molding, screen contrast increased by 50%, showing the application of image quality compared to the previous display better.

2, Printed circuit board process selection: With high-density trend, 4-layer, 6-layer plate is adopted, the printed circuit board will be used micro-hole and buried hole design, printed circuit graphics wire fine, micro-porous narrow spacing, processing in the use of mechanical method drilling technology can not meet the requirements. The rapid development of laser drilling technology will meet the micro-hole processing.

3, printing technology: Too much, too little amount of solder paste and printing offset directly affect the high-density display tube welding quality. The correct PCB pad design needs to communicate with manufacturers after the implementation of the design, the opening size of the screen and the correct printing parameters directly related to the amount of solder paste printing. General 2020RGB Device using 0.1-0.12mm thickness of electric polishing laser steel mesh, 1010RGB The following devices are recommended to use 1.0-0.8 thickness of the steel mesh. The thickness and opening size are proportional to the amount of tin. High-density LED welding quality and solder paste printing is closely related, with thickness detection, SPC analysis and other functions of the use of printing presses will play an important role in reliability.

4, Placement technology: high-density display of the RGB device location of the fine offset will lead to uneven display screen, it is bound to require more high-precision placement equipment, Panasonic NPM Equipment placement Accuracy (qfn±0.03mm) will meet the requirements of P1.0.

5, welding process: reflow soldering temperature rise too fast will lead to wetting imbalance, it is bound to cause the device in the process of wetting imbalance caused by offset. Excessive wind cycles can also cause the device to shift. As far as possible 12 temperature zone reflow soldering machine, chain speed, temperature rise, circulating wind as a strict control project, that is, to meet the welding reliability requirements, but also to reduce or avoid device displacement, as far as possible to control the scope of demand. Generally, the 2% range of pixel spacing is used as the control value.

6, Box assembly: The box is a different module splicing, the flatness of the box and the gap between the modules directly related to the overall effect of the box assembly. Aluminum plate processing box, cast aluminum box is now widely used box type, flatness can reach 10 wire inside. The splicing gap between modules is evaluated with the spacing of the closest pixels of the two modules, and two pixels too close to the bright line, the two pixels too far can lead to dark lines. Before assembling, it is necessary to measure and calculate the joint of the module, and then use the relative thickness of the metal sheet as the fixture to insert the assembly beforehand.

7, screen Assembly: Assembly completed cabinet needs to be assembled into a screen after the display of fine screen, video. However, the size tolerance and assembly cumulative tolerance of the box can not be neglected in the assembling effect of high-density display. The pixel spacing between the box and the box is too large and too small will result in the display of dark, bright lines. Dark lines, bright line problem is now high-density display can not be ignored, need to overcome the problem. Part of the company through the 3m tape, small adjustment nut to adjust the box to achieve the best results.

8, System Card selection: High-density display light and dark lines and uniformity, color difference is led device differences, IC current differences, circuit design layout differences, assembly differences, such as the accumulation of criticism, some system card company through the software correction can reduce the light and dark lines and brightness, chroma uneven. Nova introduced the brightness, color correction system has been applied to the high-density display, and achieved a good display effect.

The high-density display has the fine display effect, must start from the material choice, the circuit design, the temperature rise control, the craft and so on each link. believe that high-density display with the progress of technology, the price of the populace, will achieve greater and broader market share.

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8 large-angle high-density small-pitch LED screen technology