Current Status and Development Trend of COB Packaging

With the gradual maturity of the LED application market, users are more and more demanding on the stability and reliability of the products. Especially under the same conditions, the products are required to achieve better energy efficiency index, lower power consumption, and more competition Force product prices. It is based on this, compared with the traditional LEDSMD chip package and high-power package, chip-on-chip (COB) integrated packaging technology will be more than a few LED chips directly packaged in the metal-based printed circuit board, as a lighting module through the substrate directly Cooling, not only can reduce the manufacturing process of the stent and its cost, but also has the advantage of reducing the thermal resistance of the heat, it has become a lighting business owners push a package.

 

In addition to COB light heat dissipation, low cost, but also for personalized design. However, technically, the COB package still has the problems of light failure, short service life and poor reliability. If it can be solved, it will be one of the leading directions for the development of the package in the future.

 

COB performance tends to be stable, widely used

COB products are mainly used in commercial lighting market. As technology improves, the performance of high-power COB products tends to be stable. Recently, COB products have been gradually applied to outdoor lighting, including LED high bay lamps and street lamps. Due to the product design advantages and high light intensities that high-power LEDs and COB LEDs have, they will be able to enhance the competitive edge of the high-end lighting market.

 

First of all, in the high-end commercial lighting market to lighting used in museums, galleries and other display space market, mainly downlight, spotlights and reflector lights. According to the data, 40% and 75% of the most widely used downlights and tracklights in the global high-end commercial lighting market adopt COB light source (calculated according to the number of lamps, mainly COB below 30W) ), Followed by a compound growth of 11% and 6% respectively.

 

In addition, car COB is one of the areas of application of COB. However, due to the fact that the COB market itself is a small niche market and the vehicle COB is one of the branches of this niche market, there is less concern in the industry. However, as many COB manufacturers began to cut into the car COB market on a large scale, the car COB soon became the main battlefield of the price war. Zheng Haibin, deputy general manager of Siu Chi energy, said the cost is king, he does not agree with this view. In his view, the main COB car after-loading market, relatively low entry barriers, price competition is relatively large is normal. For any market, just enter the product standardization stage, can be called the Red Sea market.

 

In addition, industrial lighting offers new opportunities for small and medium-sized COB enterprises. According to the survey data, LED industrial lighting in the next few years will grow rapidly in 2016 LED industrial lighting market reached 2.932 billion US dollars, after which the annual growth rate of 16% or more, in 2016 the growth rate even as high as 24% to 2018 Year, the market size will reach 3.935 billion US dollars. At the same time, due to the fact that most of the industrial lighting is guided by invisible engineering channels, it is possible to eliminate the price war and the scale war.

 

Advantages and Disadvantages of COB Package

COB packaging applications have been used in the field of lighting for many years, its advantages in all aspects, it has been the favor of many lighting companies, COB packaging technology used in the top of the screen, what kind of spark will be wiped? Will there be some levels of acclimatization phenomenon? Together to analyze the advantages and disadvantages of COB package. It is understood that COB packaging technology used in the display, with the traditional packaging technology incomparable advantages.

 

1. Ultra-thin: According to the actual needs of customers, the thickness of 0.4-1.2mm thickness of the PCB board, the weight of at least reduce the original traditional products 1/3, customers can significantly reduce the structural, transportation and engineering costs.

 

2. Anti-collision compression: COB products are directly encapsulated in the LED chip LED board concave light level, and then cured with epoxy adhesive encapsulation, bulge the surface of the bulge into a spherical, smooth and hard, crash-resistant wear .

 

3 large angle: COB package uses a shallow spherical light, the angle is greater than 175 degrees, close to 180 degrees, but also has better optical diffuse color muddy light effect.

 

4. Bendable: Bendability is a unique feature of COB package, PCB bending will not cause damage to the packaged LED chip, so the use of COB module can easily make LED arc screen, circular screen, wave Shaped screen. Is the bar, nightclub personalized styling screen ideal substrate. Can be seamlessly spliced, making a simple structure, and the price is far lower than the flexible circuit boards and traditional display module LED shaped screen.

 

5. Cooling ability: COB product is the lamp package on the PCB board, through the copper foil on the PCB board quickly heat the wand, and the thickness of the copper foil PCB board has strict process requirements, coupled with the gold Shen Process, almost no serious light attenuation. So few dead lights, greatly extending the life of the LED display.

 

6, wear-resistant, easy to clean: the surface of the bulge bulge into a spherical, smooth and hard, crashworthy wear and tear; appear dead pixels, you can point maintenance; no mask, dust, water or cloth can be cleaned.

 

7, all-weather excellent features: The use of triple protection, waterproof, tide, rot, dust, static electricity, oxidation, UV highlight; meet all-weather working conditions, minus 30 degrees to 80 degrees above zero temperature environment can still be used normally.

 

To put it, COB shows the advantages of the package is really a lot, especially compared with the traditional package form, then the contrast effect is even more obvious. Since there are many advantages, why not in the early development of LED display get large-scale use of it? COB package inadequacies reflected in where? Hu Zhijun, vice president of Shenzhen Overseas Chinese Shun Photoelectric Co., Ltd. said: "COB packaging is the only drawback is not good control of the screen color is the light does not light when the surface is inconsistent ink color." Yang Rui, director of marketing, also admitted: "COB shows that the flawed packaging is that the surface consistency is not enough, this problem is not resolved, it is difficult to get the customer's approval."

 

 

COB packaging process interpretation

COB packaging technology has been classified as packaging-free or province package mode, but this package is not to save the packaging process, but eliminates the need for packaging process, and COB packaging process compared to the province To a few steps, to a certain extent, save time and technology, but also to a certain extent, cost savings. SMD production process needs to go through the solid crystal, wire, dispensing, baking, stamping, color separation, taping, patch and other links, and COB process simplified on this basis, the first IC is attached to the circuit board Then solid crystal, wire, testing, dispensing, baking, into a finished product.

 

Just on the production process point of view, eliminating the need for several steps, industry sources said, this way, you can save a large part of the cost. It is noteworthy that, COB package does not require reflow, which has become one of the advantages of COB. Yang Lei, director of marketing at Ala Lei, said the conventional package is to place the lamp beads on the PCB board for welding. When the lamp is getting closer and closer, the lamp legs will be smaller and smaller, so the precision requirement for welding will be higher. A square how many lights, a lamp has four feet, then a square there will be a lot of solder joints, this time, the requirements for the solder joints is very high, then the only solution is to reduce the solder joints. Very small solder stability is very poor, you may touch it, it is possible to fall off, which is the SMD can not be avoided; COB package eliminates the need for spectrophotometric separation, drying and other processes, the key difference is to remove the solder Process, SMD in the solder process, the temperature control is extremely difficult to grasp, the temperature is too high, will cause damage to the lamp is too low, the solder is not completely melted. It is easy to cause Weld, false welding and so on, for the stability of the lamp beads is a big challenge. COB without this process, then the stability will be greatly improved.

 

Conventional LED display processing more numerous, especially in the process of reflow, SMD LED bead holder and epoxy under high temperature expansion coefficient is not the same, can easily lead to bracket and epoxy package shell off, there Cracks, the gradual emergence of dead lights in the late use of the phenomenon, leading to higher rates of non-performing. The reason why the COB display is more stable, because there is no reflow process in the post lamp, even if there is a post-reflow IC process, the diode chip epoxy resin package has been cured and protected, to avoid the welding Machine caused by high-temperature solder ball holder and epoxy resin gap between the issue.

 

COB package is facing the challenge

A new product and the emergence of new technology and new technology, never down the road, in the R & D and production process of continuous testing, keep trying, will find the problem lies in the right remedy in real time. The emergence of each problem are R & D personnel research process, in this process, full of hardships, but also accompanied by achievement and satisfaction. The development of all new things is improving little by little, and it is also approaching success step by step. But for now, the development of COB packaging technology can not be called mature, after all, the development of new things still take time. At this stage, COB packaging technology also faces some challenges, these challenges, but also the continuous efforts of enterprises gradually improved. It is understood that at present, COB packaging technology there are still three challenges.

 

1, the packaging process of a pass rate

COB package due to its characteristics, COB package is to be in a large board, this board has a maximum of 1024 lights, SMD, if a lamp is damaged, only need to change one on the line, but COB package of 1024 After the lamp package is completed, to be tested, all the lights to confirm no problem, in order to seal. How to ensure the entire board 1024 lights completely intact, a pass rate is a very big challenge.

 

2, the finished product once pass rate

COB product is the first closure of the lamp, sealed lamp, the IC drive device to be reflow process, how to ensure the lamp surface in the reflow process, the furnace temperature of 240 degrees does not cause damage to the lamp. This is another big challenge. Compared with the SMD, the COB saves the light reflow process. However, the device surface needs the same reflow process as the SMD. That is to say, the SMD needs to be reflowed twice, Yes, SMD over reflow, the furnace temperature will cause damage to the lamp surface, one is the wire, the temperature is too high, it will rapidly rapid expansion, will cause the filament pulled off, and the second is The heat in the furnace is rapidly transferred to the wick via the four pins of the holder. The wick may cause finely fragmented damage, which is fatal. The detection is often difficult to find, including the aging test, which is difficult to detect. However, This tiny tiny damage to the crystal cracks, over time.

 

Use, this drawback will be highlighted, which led to failure of the lamp. The COB is to ensure that the lamp surface after reflow when the furnace does not cause damage to its high temperature to ensure yield, which is also very important level.

 

3, the whole lamp repair

For the COB lamp maintenance, need a professional together to repair and maintenance. The single lamp maintenance has one of the biggest problems is that after repair, the lamp will appear around a circle, repair a lamp, around the torch will be smoked, maintenance is also relatively high difficulty.

 

There are challenges that need to find the appropriate solution, for the moment, COB package in the packaging and maintenance problems encountered during the process, companies have come up with the corresponding solutions, such as the light reflow soldering time, the use of a Ways to protect the lamp face, reducing damage; in the maintenance process using point-by-point correction technology to ensure consistency between the lamp beads.

 

Research on the Development Trend of COB Package

One of the advantages of COB packages is that they are encapsulated directly on the PCB without being limited by the lamp beads. Therefore, it is unscientific for the COBs to be spaced apart. Theoretically, it is very easy for a COB package to achieve high density . To borrow a word from the industry, COB package is tailored for small spacing.

 

Yang Rui, director of marketing at Aoleida, said: "COB does not take the conventional screen line. Products made out of it will lose their meaning. COB is mainly used in small-screen displays. Currently, small-screen displays have more applications in security areas. One of the main areas of application for COB displays is security. "

 

Hu Zhijun, deputy general manager of Wei Qiaoshun Optoelectronics Co., Ltd., also expressed the same view. "SMD solves the problem of solder fillets. One lamp bead has four fillets, so as the density of the display is higher, the unit square meter The lamp beads will be more, the welding legs will be more and more dense, this problem can not be solved, and the miniaturization of the SMD is a very big challenge. The COB skips this part of the bracket and millions of solder joints All the problems are thrown away, so miniaturization easier to do together. "" COB package is a feature that can be a good solution to the problem of outdoor protection, Wei Qiaoshun adopted a "rural encircling the city" strategy, the first The development of small outdoor space, for the COB, even to P3, P2.5, P1.8, are easy to achieve, so Wei Qiaoshun intend to seize the moment to seize the opportunity to break the outdoor small spacing, the use of high reliability advantages Detours to infiltrate areas of small indoor spaces. "Hu Zhijun thus portrayed the blueprint for future development.

 

"We think COB has very good development prospects, because the reliability of COB products is far higher than the surface-mount products, which is the first point; the second point, COB products with the lower the point density, the lower its cost, the more Close to the common people, which are two very important characteristics, they are enough to support the COB towards a better future.

 

"For COB, it is not limited by the lamp beads. The following can be easily done below 1.0, but the manufactured product will lose its meaning and value without the market. The COB display is hope for the future, but this article Road to go smoothly, it will take some time, because in order to solve the problem of consistency also need to make more efforts.COB is a very good trend.Because the price of both is similar, but the cost of COB To about 15% lower, one is the process, to save a few processes, while the other is to achieve more easy to batch. "

 

 

COB next profit growth where?

Among the many fields of application of COB, the competition has been extremely fierce due to the large number of participating companies in the fields of business license and vehicle lighting. Looking at the current stage of the LED packaging industry, some companies make large-scale transformation to open up markets for flood lighting and seek diversified development to gain new high-margin growth points. Some enterprises also focus on product upgrades in the field of LED packaging by optimizing products Performance and quality, kill the Red Sea.

 

The COB as one of the niche market, business license, car lighting and other areas into the Red Sea, the next profit growth point where?

 

In this regard, Wang Meng source general manager of Optoelectronics believes that the next COB profit growth in the COB flip chip COB and light engine COB module applications. He predicts that in the next three years, the COB will gradually replace the regular COB to become the mainstream. As the light engine COB module solves the problem of luminous efficiency and safety as technology continues to mature,