I. Overview
The packaging of LED devices has been forty years. In recent years, with the rapid development of the LED industry, the application fields of LEDs have been expanding, and higher and more special requirements have been placed on the packaging form and performance of LED devices. In order to meet the different requirements of various LED application fields, LED packaging companies have introduced a variety of advanced and reliable LED devices to meet the requirements of the application side, and also promote the advancement of LED packaging technology.
Second, several leading edge LED packaging devices
1. Red, green and blue in-line elliptical LEDs with high brightness, low attenuation and perfect light distribution
In the outdoor large-size, high-brightness, dynamic, weather-resistant display field, LED display is undoubtedly the only choice. In recent years, with the improvement of cost performance, full-color LED display has replaced the single-color display to become the mainstream product of outdoor display, and it shines in outdoor advertising, information display, stage background, building decoration, outdoor signboard and other fields. The high-tech LED display products at the 2008 Beijing Olympic Games gave the world a deeper understanding of the advantages of LED display.
At present, 90% of the display devices of outdoor large-scale color LED display are red, green and blue in-line elliptical LEDs. Since every square meter of outdoor LED display contains tens of thousands of LED devices, and each hundred square meters of color display contains millions of LEDs, the oval LEDs for such display applications belong to the high-end LED field, and the following major advantages are required. Features: 1 high brightness; 2 high anti-static; 3 consistency (wavelength, highlight, angle); 4 low attenuation; 5 low failure rate; 6 red, green and blue light distribution consistency.
It is well known that LED devices in this field have been monopolized by foreign brands for some time. Fortunately, in the past two years, domestic packaging technology has made great progress, and there are possibilities for catching up in the above six aspects.
In terms of high brightness, with the advancement of the chip manufacturing process, the current highest brightness chip in China has been able to reach or reach the foreign level, thereby achieving the goal of high efficiency and energy saving.
In terms of high antistatic, the current elliptical LED has an antistatic capacity of 4,000 volts (human body mode), which can meet the demanding production and application environment of the application end.
In terms of high consistency, the wavelength and brightness can be effectively screened by a spectroscopic color separation machine. The consistency of the angle is controlled by precise solid crystal, sealing equipment and good process control, plus excellent elliptical lens design, which can achieve the consistency of different batch angles of the same machine, and the discrete performance control of the angle. Within the valid specifications.
Low attenuation, by using high UV resistance of the outer sealing glue, excellent solid crystal low glue and low thermal resistance heat dissipation structure design, can now effectively control the attenuation of LED, especially the attenuation of blue and green LED control 3000 hours 20mA is less than 10% after normal temperature, so the red, green and blue attenuation is kept consistent and small, so that the color LED display will not cause brightness degradation and color distortion for a long time.
In terms of low failure rate, by selecting high-matching packaging materials, advanced packaging technology and strict quality control, the failure rate of LED devices is less than 30PPM within 3000 hours of normal operation, reaching the international level.
Red, green and blue light distribution consistency, through the excellent computer optical design software and a thorough understanding of the package characteristics, design a red, green and blue elliptical lens mold with high light distribution consistency, making the LED full color display white at any angle The balance is relatively consistent, thus ensuring the color reproduction and fidelity of the LED color display.
The perfect combination of the above five performances can meet the needs of high-end full-color LED display.
At present, such elliptical red, green and blue LEDs are used in outdoor full-color LED display applications, and domestic LEDs have occupied half of the country, and the high-end products have been able to compete with foreign products.
2, high protection grade outdoor SMD
SMD LED is a new type of LED device, especially the top-emitting TOP SMD has small size, ultra-thin, high brightness, large angle and so on. However, such devices are often used indoors and do not have outdoor protection. With the increasing demand for outdoor use of SMD devices in recent years, especially the demand for outdoor full-color display and outdoor building lighting, high-protection outdoor SMD came into being.
SMD is used in outdoor full-color SMD display, with ultra-small pixel point spacing, high production efficiency, large horizontal and vertical angle, good color mixing effect, high contrast, etc. With the improvement of SMD brightness, it can now meet the outdoor display of 20mm point spacing. Screen 5000 nits brightness requirements.
Outdoor high-protection grade SMD needs to meet the harsh conditions of high temperature resistance, high humidity resistance and UV resistance. Therefore, the adhesion between the metal bracket and the PPA material, the UV resistance of the outer seal glue, the UV resistance of the PPA material, and the sealant glue The key factors such as the adhesion properties of PPA and the permeability of the outer seal glue should be solved through material selection, test process and control.
There are currently not many companies with high-protection outdoor SMD technology. It is expected that the introduction of this type of SMD will greatly promote the application of SMD in outdoor display lighting, reduce the cost of the previous extra cost of installing waterproof design, and simplify the design.
3, wide color gamut, low attenuation, high color temperature stability white SMD
In the next five years, an important application area for LED devices will be large-size LCD backlights, especially large-size LCD TVs. Traditional LCD CCFL backlights are being phased out due to their shortcomings of environmental protection, high energy consumption, narrow color gamut and short life. According to reports, due to the long life, low power consumption and wide color gamut of LED backlights, LED backlights account for 40% of the LCD backlights shipped in July 2009.
Although LCD LED backlights have a RGB color mixing solution in addition to the white SMD solution, due to economic and technical reasons, this solution has basically withdrawn from the market, and white SMD has become the mainstream solution for LCD LED backlighting.
White SMDs for large-size LCD backlights require the following features: 1 high light efficiency; 2 low attenuation; 3 wide color gamut; 4 high color temperature stability.
At present, the leading color efficacy level of the wide color gamut white SMD is on average from 50 lm to 60 lm per watt. Different sizes of LED chips, different package forms, and different phosphor ratios have different luminous effects. There is still a big gap between the wide color gamut white SMD light effect and the non-wide color gamut white SMD. The former is only about 60%, and this aspect needs to be further improved to reduce energy consumption.
The attenuation level of white SMD in wide color gamut is an important indicator. In addition to the attenuation factor of conventional white SMD, it is mainly related to the stability of wide color gamut phosphor. It is necessary to select a wide color gamut phosphor with good stability and Matching high performance fluorescent glue.
The color gamut of the white SMD determines the color and fidelity of large-size LCD screens. Therefore, it is necessary to select a high-efficiency phosphor having three peaks of RGB. Currently common is the RG phosphor with blue chip solution.
The color gamut stability of the wide color gamut white SMD will affect the color consistency and stability of the entire LCD screen. Because the LCD backlight module usually consists of hundreds of SMDs, the color temperature of these hundreds of SMDs will be stable and consistent for a long time. Directly affect the stable color performance of the LCD screen.
With the strong growth of large-size LCD backlight LEDs, the wide color gamut SMD packaging technology will be more perfect and progressive.
Third, the conclusion China is a large LED packaging country, but also a major application of LED. The strong demand for LED applications will promote the development and advancement of China's LED packaging technology. China's LED packaging companies are expected to gradually occupy the high-end packaging technology field.
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