As a display product with high engineering and customization, LED display screen mostly appeared near the building surface and square and other landmark buildings in the image of outdoor large screen at the beginning of its birth. However, with the point spacing of LED display products from Pxx to PX, and then breaking through P1 and marching towards p0.x, LED display products began to penetrate towards indoor application, In the early era of outdoor large screen, the "sense of distance" between users and users is getting closer with the continuous decline of point spacing. This is illustrated by Samsung's entry into led film screen, or the mutual achievements between E-sports venue construction and LED display manufacturers. Therefore, the debate on "whether the development of LED display products with smaller spacing has practical significance" has obviously settled: for LED display manufacturers, the smaller and smaller point spacing is the basis for LED display screens to penetrate the indoor market and expand more segments. On the eve of the "5g 8K" era, only when the point spacing is smaller and smaller, The interactivity of LED display screen is possible.
The development and maturity of small spacing technology has shortened the distance between LED display screen and audience. When the picture of LED display products begins to become clearer and clearer, how to further shorten the distance with users and make LED display screen interact with users has become a problem that manufacturers must consider.
Although compared with other display methods, LED display has the advantages of fast response speed and high dimensional freedom, in terms of touch screen technology, the difficulty of LED display in realizing touch interaction is significantly higher than that of other technologies: if LED display wants to realize interaction, it must reduce the point spacing as much as possible, so that the picture still has no obvious difference even when viewed at a very close distance "Granular", but with the reduction of point spacing, it is bound to face the stability and safety problems caused by the reduction of welding feet. For LED display, as a discrete device assembly product, compared with other display products, LED display products have "congenital deficiencies" in stability , even the bumps during transportation may cause the display failure of the screen. Therefore, at this stage, many LED displays often make "no touch" during exhibition and use The reason is that when the audience touches, it is very easy to leave the sweat and grease secreted by the fingers on the screen, resulting in the hidden danger of short circuit and reducing the service life of the lamp beads, and the static electricity carried by the human body may cause electrostatic breakdown. Therefore, it can be imagined that the touch caused by the audience's touch interaction is obviously stronger and more frequent than that during transportation In terms of screen, it is no accident that the pace of LED display is always slow compared with other display means. Although some manufacturers choose to solve the above problems by coating the screen surface, overall, LED display enterprises still have a long way to go on how to solve a series of problems such as dead light, bad light, short circuit and electrostatic breakdown caused by touch
However, with the advent of the "5g 8K" era, ultra-high definition video display and ultra-high speed signal transmission will inevitably put forward higher technical requirements for display products, which will inevitably include the improvement of touch control requirements. In order to make the display screen "within reach", the first thing to consider is how to improve the stability and security of the screen.
At present, there are different types of LED packages in the market, among which * N in 1 SMD (4 in 1 / 6 in 1) often appears The product is not only an extension of the SMD technical route, but also a transitional product of the traditional SMD production plant. This product is still pasted with SMT technology, using 4 in 1 lamp beads. The distance between the edge of the lamp beads and the internal solder joints is about 0.1mm. The core problems such as the air tightness of the edge of the lamp beads and the bare welding feet have not been fundamentally solved, and the problem of product reliability will be exposed again during delivery and use Under normal conditions, a 0.25mm gap needs to be reserved between the lamp beads. In addition to the size specifications of discrete devices, it is basically impossible to supply in batches below 0.9mm. At the same time, N in 1 products have a stronger sense of particles in the display effect and serious discrete hemp spots in the side view angle.
Therefore, at present, formal dress technology has come to "you can't have both fish and bear's paw" , because of the dilemma between size and stability, when it is close to the small-size ceiling, some manufacturers begin to find another way and use flip chip technology for packaging. Because flip chip technology directly bonds the light-emitting chip with the pad of PCB board and adopts solderless packaging process, the welding area is from point to surface, which increases the welding area and reduces the welding cost at the same time Therefore, the product performance can be more stable.
As an upgraded product of formal cob, flip cob further improves its reliability on the basis of the advantages of ultra-small dot spacing, high reliability and non glare of formal cob. The packaging layer has no welding line space, and the packaging layer is lighter and thinner, reducing thermal resistance, improving light quality and improving the service life of display screen. It has ultra-high protection, anti-collision, shockproof, waterproof, dustproof, smoke and static electricity. More important What's more, because it inherits the characteristics of cob overall packaging, it has a high degree of guarantee in terms of touch smoothness, does not have concave convex feeling during touch operation, and can withstand touch operation with high intensity and frequency. There is no need to worry about excessive force damaging the lamp beads during touch.
It can be said that flip chip cob is a true chip level package, because it does not need wiring, and the physical space size is only limited by the size of light-emitting chip, which breaks through the point spacing limit of formal chip and has the ability to further explore the point spacing. Therefore, compared with SMD and other packaging forms, flip chip cob is in "human screen zero distance interaction" because of the above characteristics Before the advent of the era, it had the advantage of being one step ahead of other packaging methods on the road of touch screen R & D. it should be noted that with the increasingly obvious advantages of flip technology, some SMD manufacturers also began to try to use flip technology for packaging. However, considering the cost, the number of enterprises currently choosing flip SMD is still less than that of flip cob enterprises.
However, while affirming the advantages and progress of flip-flop cob, we should also note that there will be no perfect technology in the world. No matter what kind of flip-flop technology, the threshold increase brought by technology improvement and the cost increase brought by front-end equipment upgrading are all problems that manufacturers choosing flip-flop technology must face, especially the dependence of flip-flop cob technology on machines The reliability is higher, so the operation risk brought by the replacement and upgrading of the machine is also the risk that every enterprise needs to face when making choices. While the flip cob has made progress on the basis of the formal cob, it also inherits the shortcomings that the formal cob cannot be repaired by a single lamp and the ink color is uneven, but the shortcomings are not hidden. Although the disadvantages of the flip cob are obvious, the flip cob is better in the manufacturing of LED touch screen Cob still has great advantages over other packaging methods. Therefore, it can be imagined that with the continuous exploration of point spacing, the increasing maturity and commercialization of flip cob technology, and the comprehensive arrival of the era of "within reach" of LED display screen, it will undoubtedly become a practical possibility, not just a theoretical assumption.