The new phase of PK technology from pitch to package, small pitch LED

ISLE, known as the world's most prestigious LED display industry event. 2017 ISLE, COB small pitch LED debut on the stage to bring visitors a refreshing look, breaking the previous various types of LED manufacturers in the space more and more small competition. This also means that, for the entire LED industry, people are no longer just to separate the different spacing of LED products, different packaging technology has become a distinction, choose another key LED products.

Into the indoor market, the advantages of small spacing LED

LED products are available at the beginning, because of its high brightness, bright colors and other characteristics in the outdoor market, but seldom in the indoor field ". However, with the development of technology, the emergence of small spacing LED (P3.0), making LED indoor applications become a reality.

The small spacing of LED products

From a technical point of view, although the small spacing LED in the indoor application is still a long time, easy to watch and other issues, but it is undeniable, but also has its inherent advantages. The first is the "seamless", from the visual effect, small spacing LED can do the whole screen seamless display, the screen is more complete. In addition, the interior of the big screen project, the space, the area is often limited, and small spacing LED thin, screen thickness of less than 100mm, compared to the provincial space. Furthermore, the small pitch LED brightness is high, and its brightness can be adjusted between 350~2000cd/m2, the ability to adapt to the environment is more light. Finally, the small spacing LED wide color gamut, color gamut reached 114%NTSC, more colorful, especially suitable for indoor scenes in the auditorium, demonstration hall, television studio, etc..

From SMD to COB, the leap in the development of LED Technology

Previously, the user is concerned, the choice of small spacing LED is more in different spacing to make the choice, and spacing for small pitch LED mainly affect the unit area resolution. Currently, from different packaging technology to compare, whether it is from the technical innovation or display effect, COB small spacing LED is a great improvement on SMD small spacing LED. This also shows that in use, can be used to solve the indoor Humphreys problems based on the small spacing LED development has entered a higher reliability and effect of visual experience stage, COB packaging is one of the most important technical direction.

SMD products, the lack of traditional packaging methods

The SMD (surface mount technology) package of LED products, the upstream manufacturers will package lamp bracket, lamp cup, wafer, lead, epoxy resin and other materials into different specifications of beads. The lower screen factory commercial high-speed SMT machine, reflow welding with high temperature will be led on the circuit board, a display unit made of different spacing.

The SMD LED PCB small spacing plate cross section diagram

As the first generation of small pitch LED products, SMD small pitch LED can be said to have been widely used, but also occupy a larger share of the LED application market. However, due to the inherent principle of LED products and SMD packaging technology can not avoid the defects, in the long-term market applications, SMD small spacing LED also showed obvious deficiencies.

Dead light, bad light phenomenon. LED dead light directly affects the display effect of the screen, and the use of SMD packaging technology of small spacing LED extremely easy to use in the process of producing dead lights, bad lights. This is because the first SMD small spacing of LED in the production process, will need to light high temperature reflow (240-270 degrees Celsius) way of welding on the circuit board, and in high temperature reflow due to expansion coefficient in the lamp bracket, substrate, epoxy resin and other materials, easy to produce cracks, resulting in beads the sub healthy state in the factory. Secondly, using SMD encapsulation technology, LED lamp foot pads exposed is easily oxidized, resulting in water vapor intrusion LED chip, running in the water under the action of oxygen caused by long-term internal wick electrochemical reaction, dead lights, "Caterpillar" phenomenon. In addition, the electrostatic damage to the LED lamp can not be ignored. Small pitch SMD products are sensitive to electrostatic, bare foot pads are susceptible to electrostatic effects, resulting in dead lights.

Analysis of the causes of bad light SMD

Generally speaking, the factory will be dead manufacturers rate control within the standard value; but as time goes on, Huaidian will continue to accumulate, the general use of half a year after the dead is obvious. How to reduce the dead light rate has become the primary problem to be solved at present small spacing LED.

Poor viewing comfort. In viewing comfort, the human eye will be due to the frequent refresh of the LED screen, periodic optical signal stimulation, long time viewing and close viewing will feel uncomfortable. In addition, the existence of "blue" effect, due to the short wavelength of blue LED, high frequency, the human eye directly, long-term acceptance of the blue light effect, easy to cause retinopathy.

Low gray level is not good. In outdoor applications, the brightness of the LED display has a natural advantage. However, in normal indoor applications, large screen before the brightness of the general 200nits of the human eye for a long time to watch only comfortable. However, the brightness of the LED display will appear gray scale, affecting the image quality.

COB products, small spacing LED innovation

From a technical point of view, COB small spacing LED is the second generation of small spacing LED products.

COB (Chip On Board) is a kind of packaging technology, the circuit board of RGB packaging, mainly through the silicon wafer, the resin will lead directly packaged on the circuit board, eliminating the beads package SMD package, placement, reflow process, greatly enhance the stability of small spacing of LED products and viewing comfort.

From pitch to package, small pitch LED technology P