What should I pay attention to when using domestic COB chips?

Although COB packaging still has some shortcomings to be solved, COB is the mainstream direction of future lighting design in terms of application and cost. As early as 2011, data shows that COB packaged bulbs account for about 40%. The LED bulb market shows that it has a lot of potential for development.

Compared with the traditional LED light source, the advantages of COB are mainly as follows:

First, the COB lamp has the same brightness as the traditional LED lamp, but consumes less power.

Second, the COB lamp is a stroboscopic design, no UV, eye protection, green and environmentally friendly.

Third, the COB lamp has no chromatic aberration problem, and the illumination is uniform and soft.

Fourth, the COB lamp can create a color visual effect, which perfectly presents the true color of the object.

5. COB lamps are widely used and safe. Because it is glare-free, it won't be as dazzling as traditional LEDs, and it is not suitable for home and children.

Sixth, the COB ball is suitable for promotion. Because it has few solder joints, it does not require patching and reflow soldering, and the installation is simple and convenient.

With the increasing use of LEDs in the field of lighting, from the perspective of cost and application, the integrated COB package is more suitable for the next-generation LED lighting structure. The development of COB package is to solve the high thermal resistance in the existing SMD package structure. The main way of high cost issues. The number of COB packages will gradually increase in the proportion of LED packages with its excellent performance, especially the increase in the proportion of output value, which further promotes the popularity of LED lighting.

COB (Chip On Board) COB is a method of directly bonding a bare die to a circuit board (PCB) and bonding the wire/wire directly to the gold-plated line of the PCB. The encapsulation technology effectively transfers the packaging steps in the IC manufacturing process to the board for direct assembly.

In the past, COB technology generally used consumer electronics products that did not pay much attention to reliability, such as toys, calculators, small monitors, watches and clocks, and other daily necessities, because manufacturers of COB are generally low-cost (Low Cost). Consideration. Nowadays, more and more manufacturers are looking at its small size, and the trend of thin and light products, and the use of more and more trends, such as mobile phones, cameras, LED lamps and other short-term products.

2, COB environmental requirements

It is recommended to have a Clean Room and the Class is preferably below 100K. Because the process of COB is at the wafer package level, any small particles contaminated at the solder joint can cause serious defects.

The basic dust-free coat is also necessary. It does not need to be wrapped into a dust-free clothes, but basic hats, clothes, and static shoes are all necessary.

Also, the clean room should strictly control the carton and any items that are easily entrained or produce dander. All packaging should be unpacked outside the clean room before entering the clean room, in order to keep the clean room clean and extend the life of the clean room.

3, COB manufacturing flow chart

4, COB classification

For COB packages, there are currently two categories: (1) low thermal resistance packaging process; and (2) high reliability packaging process.

(1) Low thermal resistance packaging process

The low thermal resistance COB package is currently divided into an aluminum substrate COB, a copper substrate COB, and a ceramic substrate COB.

Due to the low cost of the substrate, the COB light source of the aluminum substrate has a high cost performance. In addition, the luminous efficiency can be up to 130LM/W. Based on the above advantages, it can be widely used with LED bulbs , LED downlights. On the luminaire, but due to the thermal conductivity of the aluminum substrate, 5-10W COB light source is suitable.

Copper substrate COB, because the chip is directly fixed on the copper, the heat conduction effect is good, can encapsulate 20-50W COB, and the light efficiency can reach 130LM/W. It is widely used in LED projection lamps, LED street lamps, etc., but to prevent Local overheating, generally package 20-50W COB light source.

Ceramic substrate COB, ceramic is currently recognized as the most suitable material for LED packaging substrate, with its excellent thermal conductivity, excellent insulation performance, small thermal deformation and other advantages. Widely used in high-grade, high-reliability LED lamps, currently packaged 10-50W COB light source, but due to its expensive substrate, it is generally used in the field of high-end LED lighting and high reliability requirements.

(2) High reliability packaging process

At present, for the lighting of some special occasions, the reliability requirements of LED lamps are particularly high, such as LED street lamps, LED tunnel lights, LED explosion-proof lamps, LED miner lamps, etc., so the reliability requirements for LED light sources are also very high.

The thermal impact of LED packaging as one of the top three effects (heat effects, electrostatic effects, moisture effects) affecting reliability is an important cause of LED attenuation. According to the Arrhenius model for LED chips, for every 10 °C increase in junction temperature of LEDs, the lifetime of LEDs will be reduced by one and a half.

Due to the high thermal conductivity and insulation properties of the ceramic substrate, the thermal influence and electrostatic influence can be solved. In addition, the ceramic substrate and the silica gel have good bonding properties, which can solve the influence of moisture, and the use of the flip chip process to remove the gold wire further The reliability of the entire light source component is improved, and the COB package is used to improve the cost performance of the light source component. Therefore, the ceramic substrate COB plus flip chip process can meet the demanding LED application field.

Although COB light source has many advantages, such as low thermal resistance, high reliability, and high cost performance, it still needs to consider color rendering and stability in practical use, especially domestic COB.

What is the performance stability and life of domestic COB chips? Is there any comparison data in this regard?

(Quality and price) are directly proportional. : The domestic LED fabric core has problems. Although the luminous flux color rendering performance is very good, the central light intensity is not good, basically it is 10000cd徘徊, and it has not been measured yet. I always feel that in some places where the lighting time is more than 12 hours, the lamps with domestic COB chips have no bottom. It is meaningless to say that the light is strong.

Since the LED will produce light decay, in order to ensure the illumination demand in a certain period, the common practice is to match the constant illumination power supply, and to compensate for the lack of illumination caused by the light decay when the light decays automatically, the above is the constant illumination power supply. The advantages of using. The constant illumination power supply is not omnipotent and needs to have sufficient margin. More and more electricity has also sacrificed the interests of customers? This has been considered at the beginning of the design, the current working range can reach 1A, compared to the lighting effect, the electricity bill can be accepted. This depends on the need to be so bright, if the corridor does not matter, the stadium that needs high-definition live broadcast is estimated to be necessary. The current does not work much until 1A, and the lamp current is not large. There are several amps of power supply for multiple parallel lamp beads. I am talking about the current adjustable range. I did not say that I push a single lamp bead. It is necessary to leave a surplus for the lamp beads, but most of them are currently used up.

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