LED Display Screen Is Touchable

- May 13, 2020-

As a display product with high engineering and customization, at the beginning of the birth of LED display screens, most of them appear as outdoor large screens near the building surface and squares and other landmark buildings, but with the dot spacing of LED display screen products From PXX to PX, and then to break through P1, and continue to march in the direction of P0.X, LED display screen products began to penetrate into the direction of indoor applications, the "sense of distance" between the early outdoor large-screen era and users is following The continuous decline of the distance and the continuous narrowing, whether it is Samsung's entry into the LED movie screen, or the mutual achievements between the construction of e-sports venues and LED display screen manufacturers, all illustrate this point. Therefore, the debate about whether it is practical to develop smaller-pitch LED display screen products was clearly settled: For LED display manufacturers, the dot pitch is getting smaller and smaller, it is the LED display that can penetrate the indoor market and expand more The basis of multi-segment fields, and on the eve of the arrival of this "5G + 8K" era, only when the dot pitch becomes smaller and smaller, the interactivity of the LED display can be realized.

   The development and maturity of small-pitch technology has shortened the distance between the LED display and the audience. When the picture of the LED display screen product begins to become more and more clear, how to further reduce the distance from the user User interaction has become a problem that manufacturers must consider.

  Although LED display screen has the advantages of fast response speed and high degree of freedom compared to other display methods, in terms of touch screen technology, LED display screen is more difficult to achieve touch interaction than other technologies: LED display screen wants to achieve For interaction, the point spacing must be reduced as much as possible, so that even when the picture is viewed at a very close distance, there is still no obvious "graininess", but as the point spacing decreases, it will inevitably face the stability brought by the reduction of the solder foot With regard to safety issues, as for LED display screen, as a discrete device assembly product, LED display products have "congenital deficiencies" in stability compared to other display products, even bumps during transportation may cause the screen body The display is faulty, so at this stage, many LED display screens often make a "prohibited touch" label during exhibition and use, because when the audience touches, it is easy for the sweat and grease secreted on the finger If left on the screen, it may cause a short circuit and reduce the life of the lamp beads. The static electricity carried by the human body may cause static electricity breakdown. . Therefore, it is conceivable that the touch caused by the audience ’s touch interaction is obviously stronger and more frequent than the collision during transportation. In terms of touch screen, the pace of LED display screen is always slower than other display methods. It is no surprise. Although some manufacturers choose to solve the above problems by coating the surface of the screen, in general, in terms of how to solve a series of problems caused by touch, such as dead lights, bad lights, short circuits, electrostatic breakdown, etc., LED display screen companies still have a long way to go.

   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, and this will inevitably include the improvement of touch requirements. In order to make the display "accessible", the first thing to consider is how to improve the stability and security of the screen.

   At present, the types of LED packages on the market are different. Among them, the most common N in 1 SMD (4 in 1/6 in 1) products are an extension of the SMD technology route and a transitional product of traditional SMD production plants. SMT technology is still used for mounting, using 4 in 1 lamp beads, the distance between the edge of the lamp bead and the internal solder point is about 0.1mm, the core problems such as air tightness of the lamp bead edge, bare solder legs, etc. have not been fundamentally resolved, and product reliability The problem will be exposed again in the process of delivery and use, and it has not been effectively improved. Under normal conditions, a gap of 0.25mm needs to be reserved between the lamp beads, and the size of the discrete device specifications, it is basically impossible to achieve mass supply below 0.9mm. At the same time, N in 1's products are more grainy in display effect, and have discrete pitting in the side view angle.

   Therefore, in the current formal wear technology has come to "both fish and bear's paw can not have both", due to the dilemma between size and stability, and therefore close to the small size of the ceiling, some manufacturers began to find another way to adopt flip Technology for packaging. Because the flip chip technology directly bonds the light emitting chip to the pad of the PCB board, and uses a solderless wire packaging process, the welding area is from point to surface, which increases the welding area while reducing the number of welding points, so it can make the product performance more stable.

   As an upgraded product of the formal COB, the flip COB further improves the reliability on the basis of the ultra-small pitch of the formal COB, high reliability, and non-glare surface light source. The package layer has no bonding wire space, the package layer is lighter and thinner, and the heat is reduced. Resistance, improve light quality, and increase display life. Super high protection, anti-collision, anti-shock, waterproof, dustproof, anti-smoke, anti-static. More importantly, because it inherits the characteristics of the COB overall package, it has a high degree of guarantee in touch smoothness, does not have a bumpy feel during touch operation, and can also withstand high-intensity and frequency touch operations Don't worry about the situation that the lamp beads are damaged due to excessive force during the touch.

   It can be said that flip-chip COB is a real chip scale package, because it does not need to wire, the physical space size is only limited by the size of the light-emitting chip, and it breaks through the limit of the dot pitch of the chip, and has the ability to further dip the dot pitch. ability. Therefore, compared with SMD and other packaging forms, flip-chip COB has the above characteristics, and before the advent of the "human-screen zero-distance interaction" era, it has the advantage of one step ahead of other packaging methods on the road of touch screen development. It should be noted that as the advantages of flip-chip technology become more and more obvious, some SMD manufacturers have also begun to use flip-chip technology for packaging, but for cost considerations, the number of companies currently choosing flip-chip SMD is still less than the flip chip. Install COB enterprises.

   However, while affirming the advantages and progress of flip-chip COB, we should also note that there is no perfect technology in this world. No matter what kind of flip-chip technology, the threshold of technology improvement and the upgrade of front-end equipment The cost increase is a problem that manufacturers who choose flip-chip technology must face, especially flip-chip COB technology, which relies more on the machine, so the operational risk brought by the replacement and upgrade of the machine, It is also the risk that every enterprise needs to face when making a choice. While the flip-chip COB has made progress on the basis of the formal COB, it also inherits the shortcomings of the formal COB that cannot be repaired by a single lamp, and the uneven color of the ink, but the flaws cannot be concealed. Although the shortcomings of the flip COB are obvious, in terms of LED touch screen manufacturing Compared with other packaging methods, COB mounting still has considerable advantages, so it is conceivable that with the continuous exploration of the dot pitch, the flip-chip COB technology is becoming more mature and commercialized, and the LED display is within reach The arrival will undoubtedly become a practical possibility, not just a theoretical stop.