2016 small pitch LED industry once again get a bumper harvest. LED display from the industry to see the growth of small, small distance LED TV has won almost 90% increase. In the small-pitch LED display products at the same time high-speed growth, small-distance LED display technology is also progressing. This year the COB package products become the new darling, and have become the future trend of the king.
COB came, small pitch LED TV into a new stage
What is the COB (Chip On Board) small pitch display technology? That is directly LED light-emitting crystal package in the PCB circuit board, and the CELL unit into a display technology. At present, Granville, Sony and other industry giants of the technology to give strong support.
Domestic high-end large-screen display leading brand Wei Chong believes that small-distance LED display development can be divided into two stages: the first stage is to solve the problem, can use the core technology breakthrough is reflected in the pixel pitch reduced to 2 mm , P1.5 and P1.2 products mass production; small pitch LED display the second stage of development is to provide a higher product reliability and visual experience, which COB package is one of the most critical technology direction The
In the spring of 2016, Granville officially launched P1.5 standard COB package products. Industry experts believe that, with the 2016 COB package small pitch LED TV products at the beginning of meritorious service, 2017 this type of product or gradually into the "supply side of the outbreak of growth."
Simplify, COB package small pitch LED so magical
For small pitch LED screen applications, dead lights are the biggest problem. P1.6 products, for example, more than 39 million per square meter lamp beads, nearly 1.6 million with the lead. These components as a whole constitute a very complex process system problems: that is, such a complex system, should be used as a "reflow" process to achieve the connection. The reflow process itself means "artificial high temperature" (240 degrees, far more than the normal temperature of the LED display).
In the high temperature operation process, due to LED lamp beads SMD patch package of different materials, such as copper bracket, epoxy resin, crystal thermal expansion coefficient is different from the lamp itself will inevitably change the thermal stress. This became a small pitch LED screen bad lights, dead light core "culprit".
The use of COB packaging technology, in the chip after the lamination of the packaging process, LED crystal one-time to become the smallest CELL display unit, not the need for late "surface" welding. This process, by reducing the high degree of precision and high temperature environment operation, the maximum degree of protection of the LED crystal electrical and semiconductor structure stability, can make the display bad light rate decreased by an order of magnitude or more.
In other words, COB package is characterized by, LED packaging, no longer need the traditional "surface paste" process. Due to the omission of a step high temperature and high precision process, which brought the whole project system reliability enhancement. This is the core reason why the COB package is favored by the small pitch LED industry.
The overall package, COB technology a lot of benefits
From the small pitch LED screen of the bad lights and stability point of view, in addition to reflow soldering "high temperature" damage process, there are the following aspects need to attach great importance:
First, the display unit of the collision process. SMD surface lamp is not a seamless connection with the PCB board, which makes the collision process is likely to cause stress on a single lamp beads on the concentration. And large-screen system of transport, installation, etc., inevitably have shock and collision. This results in an increase in the "engineering" of the small-pitch LED display with a bad light rate. COB packaging technology, through the epoxy resin, chip, PCB board of the high degree of integration of bonding, can effectively protect the wafer and wafer electrical connection parts of the stability.
Second, the system works during the temperature uniformity. The smaller the SMD package smaller spacing products, the more to use high-power small particles of LED crystals. At the same time, the gap between the lamp beads and the display panel leads to the thermal conductivity of the wafer during operation. COB package due to the use of a more integrated overall process, making the choice of crystal can be used in the lower power density, crystal particles larger chip, thereby reducing the core light point of work intensity. At the same time, COB package to achieve the full encapsulation of epoxy resin under the solid heat dissipation, making the working state of the LED crystal heat concentration decreased, is conducive to extend product life and improve system stability.
Third, the overall packaging process, COB to "seal five anti". That is, COB can be very good to do crystal, crystal electrical connection parts of the "waterproof, moisture, dust, anti-static, anti-oxidation." In contrast to the SMD package, long-term chemical and electrical stability damage occurs in the process, especially after a shock and collision, which is one of the culprits of a long-term use of persistent bad lights.
So, the overall look, COB package is more SMD products can provide "high reliability" of the process.
From the visual effect, the COB change is not a little bit
What are the benefits of the LED display system? Highlight, colorful. However, in a system in which a single lamp base is used as a base member, the pixel granularity, the viewing angle and the picture softness are also defects in the display effect.
The traditional LED display system for outdoor display, long-distance viewing display, its viewing angle and visual comfort needs are not obvious. However, with the popularity of small-pitch LED applications, indoor display system, a large number of close-up viewing system, how to enhance the viewing comfort of the LED display has become a big industry problem.
Comparison of SMD package, COB technology under the small pitch LED products, natural is the "non-particle display", the quality of uniformity, color curve, viewing angle effects have different degrees of improvement. In the use of PCB cell board built-in point by point tuning technology, COB in the crystal and unit effect uniformity also received great progress. These changes combine to make the COB package the best technology to achieve a small pitch LED TV "visual comfort" and "experience enhancement".
The description of this is that COB "implements the conversion of the LED display unit from the 'point' light source to the 'face' light source, the picture is more uniform, no spot, combined with advanced surface coating technology, COB small pitch LED product image display Softer, effectively reduce the light intensity of radiation, eliminate moire and glare, to reduce the damage to the viewer's retina, conducive to close and long time to watch.
Dingding the next generation of small spacing LED TV new standard, COB on the road
Although COB display technology has become a small pitch LED industry tomorrow's star, but this does not mean that COB technology has been perfect.
In fact, because COB technology is a one-time CELL packaging technology, completely eliminate the reflow as the core of the surface paste process, which in itself means "packaging process" increased complexity. Including the number of crystals within the unit CELL, from the SMD red, green and blue, into thousands or even more, this complexity of the upgrade, making COB package in the CELL stage of the stability control, reliability testing For the complex.
At the same time, COB packaging technology itself started late, and long-term use for high-end light source and custom light source market, in the small interval LED display technology and material technology in the field of less than SMD technology. This results in a very small pitch product, the combined cost, COB also than the traditional SMD technology disadvantage. It is predicted that the key to COB technology in 2017 is to make more technological breakthroughs and cost breakthroughs on P1.5, P1.2 and P1.0 products.
However, depending on the COB technology's own display performance advantages, COB products have achieved very good market response. For example, in the field of radio and television studio, due to COB technology's own anti-Moire pattern characteristics, making the camera system personnel like this new technology. In the command and dispatch center market, COB's high stability, maintenance and repair convenience and viewing comfort, also received a high customer recognition. In the leasing industry, COB more to prevent the collision and vibration damage characteristics, making the rental market is very optimistic about the promotion of this product, P1.9 COB products, has become the new darling of the rental industry.
In short, technological innovation is always on the road, small distance LED display to solve the problem, how "easy to use" has become the industry competition focus - this will be the biggest opportunity for COB.