The Future of AC LEDs = Flip Chip + Si Substrate + CSP Technology
AC LEDs, non-driven light sources, light engines, and power-off have become hot topics of common concern in the industry. Not long ago, at the new product launch conference of the integrated optoelectronic module light engine organized by Zhonghao Optoelectronics, Professor Wang Gang from Sun Yat-sen University of Science and Technology spoke of the term “going to powerâ€: the word sounds “awkward†because all electronic and electrical products All are inseparable from the power supply, LED lighting is no exception. Professor Yan Chongguang from the Shanghai Institute of Microelectronics, Peking University believes that “de-powering†is actually a false proposition. What is even more strange is that many people in the industry call the AC LED "light engine" somehow? Regarding the above-mentioned various technical terms, how to classify and define them, the author believes that it is necessary to discuss these technical terms at present. It is undoubtedly beneficial to standardize the definition of AC LED technical terms, establish relevant standards, and lead the industrial market with scientific attitude.
The service life of LED lighting products is far lower than the theoretical value. The reason is that the driving power supply is easy to damage and the system life is not long. The industry circulates: "99 out of 100 lamps are caused by problems with the driving power supply." Moreover, the cost of the drive power in the overall luminaire accounts for 20% to 30%. The power supply is driven by the power supply during AC/DC conversion, and the power loss is as high as 20 to 30%. Therefore, discarding the driving power supply can not only improve the system light efficiency, reduce the cost, but also completely avoid the damage of the LED lamp caused by the problem of the driving power source.
AC LEDs can be divided into two categories: one is packaged in a single chip, and there are more LED units connected in series on the chip, and some of the LED units are used to form a rectifying path to realize AC illumination. See Figure 1.
This type of light source is represented by the Seoul company in South Korea.
The other is an integrated module invented in the United States and Germany. It uses an external AC rectification and driver to form a photoelectric integrated lighting module in the C0B package line, which is currently the most popular and well-known "light engine". See Figure 2.
The AC LED in the dry period is a multi-chip high-density synthesis. The serial-connected relative-DC package requires complex solid-crystal and money-making processes. Multiple chips form a series circuit on one chip. Damage to one will affect the normal operation of the system. In order to improve this situation, many chip factories have introduced high-voltage HV LEDs in recent years, which can greatly reduce the post-packaging process and reduce the manufacturing cost.
AC LED has already appeared in foreign countries very early. As early as 2005, Seoul Semiconductor Co., Ltd. has directly used AC power to directly drive AC LEDs, followed by the United States, Germany, Taiwan, etc., which have completed industrial production. AC LED products for practical application of system solutions. In recent years, domestic companies such as Zhuo Nai Optoelectronics Co., Ltd., CLP Jintai Optoelectronics, Xinli Optoelectronics, Hongri Optoelectronics, Zhonghao Optoelectronics, etc. have sprung up.
The biggest disadvantage of single-core AC LEDs is the connection of multiple light-emitting devices on a small die. The limited chip area limits the power output. The process affects the light efficiency, and the built-in constant current is difficult to control. When it is raised, the power of the dissipated work power is suddenly increased, which may cause damage.
The so-called "light engine", which is widely used at present, adopts the aluminum substrate COB package, and the linear constant current technology provides an effective solution for high-power output, becoming the mainstream of AC LED. However, the fatal disadvantage of this technology is that it must rely on an aluminum substrate with multiple layers of thermal resistance. The traditional aluminum (or copper) substrate is a composite aluminum substrate with a FR4 fiberboard or BT plate, which has the best thermal conductivity. Only about 2 w / mK, compared with the thermal conductivity of pure aluminum without insulation layer is 237 w / mK difference of more than one hundred times, such a large package thermal resistance, will inevitably increase the heat consumption ratio, accelerate the LED light decay, Damage, reducing the life of the LED, although some people use ceramic substrates, although the thermal conductivity has improved, but it still has many problems with the heat dissipation of the lamp body.
AC LED has just entered the growth stage, and it is not ideal in terms of brightness, medium and high power output. The main reason is the poor heat dissipation caused by SMD and aluminum substrate, which affects stability and longevity. I believe that there will be new solutions soon. The solution, its application is simple, no need for transformer converter, electrolytic capacitors and excessive peripheral components, integrated package integration technology will seize the market. AC LED technology has passed the budding period and is in a period of rapid development. From its development trend, ACLED technology will inevitably become an inevitable direction for the development of the industry. Some people think that in the near future, more than 80% of the entire application market will adopt AC LED technology, or give the driving companies a fatal blow, and will change the LED industry landscape.
As with the DC light source, the non-isolated power supply is the same. Because the input terminal is directly inserted into the high-voltage power supply, if there is no protection measure, it will cause electric shock to the human body, and it cannot pass the safety regulation. This is the most difficult technical problem for designers, and it is estimated that it will not be completely in the near future. solve. At present, most of them use physical isolation and anti-shock methods, such as the use of plastic-coated aluminum in the bulb casing or the passive structure of the light source and the insulating film, but this increases the system thermal resistance and manufacturing cost.
The stroboscopic problem is considered by many in the industry to be a problem with LED products. In fact, this is a misunderstanding. It is no exaggeration to say that this is a false proposition. Because: First of all, LED strobe has no legal provisions at home and abroad; secondly, it has no authoritative report on the adverse effects on the human body; Third: LEDs will have ripples as long as they are converted by AC/DC, but the size is different. Finally, most of the current household appliances are equipped with electromagnetic radiation or stroboscopic, such as fluorescent lights, televisions, etc. Why do so many people pass and say that they have to say NO to the LED?
Whether it is a single-chip integrated AC LED or HVLED+SMD architecture, the most basic technical requirement is constant current control, otherwise it will cause damage when the grid voltage is too high. There are many options for constant current control. In the future, it is necessary to take the simplification, high reliability and low cost. It is the most basic technical idea. The author has achieved good results with HVLED+ constant current diode + mirror aluminum COB package.
The following is a bulb made by the author using HVLED + constant current diode + mirror aluminum COB package. 3 is a light source of a HVLED+constant current diode+mirror aluminum COB package, and FIG. 4 is a bulb assembled with the light source.
Constant current characteristics: Io≦ rated current ±1.5mA when Vin=198-242 V
The author designed an AC LED bulb using the above light source, Figure 4.
The basic idea of ​​the design of this product is:
In order to be simple and complicated, the price is king.
It completely eliminated:
(1) 20-30% AC/DC energy loss.
(2) 20-30% lamp driving cost.
(3) More than 90% of the faults caused by the drive are damaged.
This product has a very high price/performance ratio:
(1) Abandoning the multilayer thermal resistance barrier of the aluminum substrate, greatly reducing the thermal resistance of the package and prolonging the service life of the light source by about 3-5 times, about 200,000-300,000 hours.
(2) High luminous efficiency 100-130 lm/w.
(3) Low light source cost price 0.5-0.8RMB /100lm/W/.
(4) Long life: 30 years of life, the cost of value is 0.3-0.5RMB/100lm/W/.
AC LED development trend:
In the future, the single-chip + SMD package may have to be placed in a high-voltage HVLED+COB package. The high-voltage HVLED is a basic component and will have the following development trends:
(1) Switch to flip chip;
(2) using a Si substrate material;
(3) Develop white light CSP technology to achieve high luminous efficiency, high stability and high power integrated process.
Some of the former LED chips use a silicon substrate. The chip electrodes of the silicon substrate can be in two contact modes, namely, Latin-co ntact, (horizontal contact) and Vertical-contact, (V contact vertical contact), through which the current inside the LED chip can be It is horizontal or vertical. Since the current can flow longitudinally, the light-emitting area of ​​the LED is increased, thereby improving the light-emitting efficiency of the LED.
Because silicon is a good conductor of heat, the thermal conductivity of the device can significantly improve the life of the part.
CSP technology was invested heavily by many companies at home and abroad for a few years ago. China has also included it in the "863" scientific research program a few years ago. Many units have research results. Simultaneous installation of chips, but also research and development from materials, processes and equipment, when the CSP technology is fully solved, once it is put into the market, it will soon replace the current SMD light source, a large number of SMD packaging plants will have to change the production pattern. According to reports, the semiconductor grade phosphor vacuum coating equipment and process independently developed by Taiwan Semiconductor Optoelectronics Co., Ltd. can form a uniform, dense phosphor with a thickness of only 30 microns on the five light-emitting surfaces of tens of thousands of flip chips. film. The dense and thin phosphor layer makes the film CSP more than 20% lighter than the CSP made by spraying or potting, and it is easier to increase the color rendering index with a color rendering index of over 95.
Any new products and new technologies will bring new markets to our entrepreneurs, and innovation is the only way for enterprises to develop. Only by seeing the trend and clear goals, will there be profit growth points. The beginning of any new thing is not perfect, and there needs to be a technical improvement and market acceptance process. AC LEDs can reduce lamp drive costs by 20%-30%. Effectively avoiding the damage of the LED lamp caused by the driving power source, it has shown its strong vitality. AC LED technology will inevitably become a direction of the development of the industry, and will revolutionize the development of the LED industry. In less than a few years, high-brightness, high-power, low-cost AC LED products will enter the market quickly, welcoming her beautiful spring!
The service life of LED lighting products is far lower than the theoretical value. The reason is that the driving power supply is easy to damage and the system life is not long. The industry circulates: "99 out of 100 lamps are caused by problems with the driving power supply." Moreover, the cost of the drive power in the overall luminaire accounts for 20% to 30%. The power supply is driven by the power supply during AC/DC conversion, and the power loss is as high as 20 to 30%. Therefore, discarding the driving power supply can not only improve the system light efficiency, reduce the cost, but also completely avoid the damage of the LED lamp caused by the problem of the driving power source.
definition
AC LED is a light source that can be directly inserted into 220V (or 110V) without the need of AC/DC conversion compared to conventional DC LEDs.AC LED technology classification
AC LEDs can be divided into two categories: one is packaged in a single chip, and there are more LED units connected in series on the chip, and some of the LED units are used to form a rectifying path to realize AC illumination. See Figure 1.
This type of light source is represented by the Seoul company in South Korea.
The other is an integrated module invented in the United States and Germany. It uses an external AC rectification and driver to form a photoelectric integrated lighting module in the C0B package line, which is currently the most popular and well-known "light engine". See Figure 2.
The AC LED in the dry period is a multi-chip high-density synthesis. The serial-connected relative-DC package requires complex solid-crystal and money-making processes. Multiple chips form a series circuit on one chip. Damage to one will affect the normal operation of the system. In order to improve this situation, many chip factories have introduced high-voltage HV LEDs in recent years, which can greatly reduce the post-packaging process and reduce the manufacturing cost.
Why AC LED technology is not easy to be accepted by users
AC LED has already appeared in foreign countries very early. As early as 2005, Seoul Semiconductor Co., Ltd. has directly used AC power to directly drive AC LEDs, followed by the United States, Germany, Taiwan, etc., which have completed industrial production. AC LED products for practical application of system solutions. In recent years, domestic companies such as Zhuo Nai Optoelectronics Co., Ltd., CLP Jintai Optoelectronics, Xinli Optoelectronics, Hongri Optoelectronics, Zhonghao Optoelectronics, etc. have sprung up.
The biggest disadvantage of single-core AC LEDs is the connection of multiple light-emitting devices on a small die. The limited chip area limits the power output. The process affects the light efficiency, and the built-in constant current is difficult to control. When it is raised, the power of the dissipated work power is suddenly increased, which may cause damage.
The so-called "light engine", which is widely used at present, adopts the aluminum substrate COB package, and the linear constant current technology provides an effective solution for high-power output, becoming the mainstream of AC LED. However, the fatal disadvantage of this technology is that it must rely on an aluminum substrate with multiple layers of thermal resistance. The traditional aluminum (or copper) substrate is a composite aluminum substrate with a FR4 fiberboard or BT plate, which has the best thermal conductivity. Only about 2 w / mK, compared with the thermal conductivity of pure aluminum without insulation layer is 237 w / mK difference of more than one hundred times, such a large package thermal resistance, will inevitably increase the heat consumption ratio, accelerate the LED light decay, Damage, reducing the life of the LED, although some people use ceramic substrates, although the thermal conductivity has improved, but it still has many problems with the heat dissipation of the lamp body.
AC LED will be the future trend
AC LED has just entered the growth stage, and it is not ideal in terms of brightness, medium and high power output. The main reason is the poor heat dissipation caused by SMD and aluminum substrate, which affects stability and longevity. I believe that there will be new solutions soon. The solution, its application is simple, no need for transformer converter, electrolytic capacitors and excessive peripheral components, integrated package integration technology will seize the market. AC LED technology has passed the budding period and is in a period of rapid development. From its development trend, ACLED technology will inevitably become an inevitable direction for the development of the industry. Some people think that in the near future, more than 80% of the entire application market will adopt AC LED technology, or give the driving companies a fatal blow, and will change the LED industry landscape.
About safety regulations
As with the DC light source, the non-isolated power supply is the same. Because the input terminal is directly inserted into the high-voltage power supply, if there is no protection measure, it will cause electric shock to the human body, and it cannot pass the safety regulation. This is the most difficult technical problem for designers, and it is estimated that it will not be completely in the near future. solve. At present, most of them use physical isolation and anti-shock methods, such as the use of plastic-coated aluminum in the bulb casing or the passive structure of the light source and the insulating film, but this increases the system thermal resistance and manufacturing cost.
About strobe
The stroboscopic problem is considered by many in the industry to be a problem with LED products. In fact, this is a misunderstanding. It is no exaggeration to say that this is a false proposition. Because: First of all, LED strobe has no legal provisions at home and abroad; secondly, it has no authoritative report on the adverse effects on the human body; Third: LEDs will have ripples as long as they are converted by AC/DC, but the size is different. Finally, most of the current household appliances are equipped with electromagnetic radiation or stroboscopic, such as fluorescent lights, televisions, etc. Why do so many people pass and say that they have to say NO to the LED?
Future AC LED development trend
Whether it is a single-chip integrated AC LED or HVLED+SMD architecture, the most basic technical requirement is constant current control, otherwise it will cause damage when the grid voltage is too high. There are many options for constant current control. In the future, it is necessary to take the simplification, high reliability and low cost. It is the most basic technical idea. The author has achieved good results with HVLED+ constant current diode + mirror aluminum COB package.
The following is a bulb made by the author using HVLED + constant current diode + mirror aluminum COB package. 3 is a light source of a HVLED+constant current diode+mirror aluminum COB package, and FIG. 4 is a bulb assembled with the light source.
Constant current characteristics: Io≦ rated current ±1.5mA when Vin=198-242 V
The author designed an AC LED bulb using the above light source, Figure 4.
The basic idea of ​​the design of this product is:
In order to be simple and complicated, the price is king.
It completely eliminated:
(1) 20-30% AC/DC energy loss.
(2) 20-30% lamp driving cost.
(3) More than 90% of the faults caused by the drive are damaged.
This product has a very high price/performance ratio:
(1) Abandoning the multilayer thermal resistance barrier of the aluminum substrate, greatly reducing the thermal resistance of the package and prolonging the service life of the light source by about 3-5 times, about 200,000-300,000 hours.
(2) High luminous efficiency 100-130 lm/w.
(3) Low light source cost price 0.5-0.8RMB /100lm/W/.
(4) Long life: 30 years of life, the cost of value is 0.3-0.5RMB/100lm/W/.
AC LED development trend:
In the future, the single-chip + SMD package may have to be placed in a high-voltage HVLED+COB package. The high-voltage HVLED is a basic component and will have the following development trends:
(1) Switch to flip chip;
(2) using a Si substrate material;
(3) Develop white light CSP technology to achieve high luminous efficiency, high stability and high power integrated process.
Some of the former LED chips use a silicon substrate. The chip electrodes of the silicon substrate can be in two contact modes, namely, Latin-co ntact, (horizontal contact) and Vertical-contact, (V contact vertical contact), through which the current inside the LED chip can be It is horizontal or vertical. Since the current can flow longitudinally, the light-emitting area of ​​the LED is increased, thereby improving the light-emitting efficiency of the LED.
Because silicon is a good conductor of heat, the thermal conductivity of the device can significantly improve the life of the part.
CSP technology was invested heavily by many companies at home and abroad for a few years ago. China has also included it in the "863" scientific research program a few years ago. Many units have research results. Simultaneous installation of chips, but also research and development from materials, processes and equipment, when the CSP technology is fully solved, once it is put into the market, it will soon replace the current SMD light source, a large number of SMD packaging plants will have to change the production pattern. According to reports, the semiconductor grade phosphor vacuum coating equipment and process independently developed by Taiwan Semiconductor Optoelectronics Co., Ltd. can form a uniform, dense phosphor with a thickness of only 30 microns on the five light-emitting surfaces of tens of thousands of flip chips. film. The dense and thin phosphor layer makes the film CSP more than 20% lighter than the CSP made by spraying or potting, and it is easier to increase the color rendering index with a color rendering index of over 95.
in conclusion
Any new products and new technologies will bring new markets to our entrepreneurs, and innovation is the only way for enterprises to develop. Only by seeing the trend and clear goals, will there be profit growth points. The beginning of any new thing is not perfect, and there needs to be a technical improvement and market acceptance process. AC LEDs can reduce lamp drive costs by 20%-30%. Effectively avoiding the damage of the LED lamp caused by the driving power source, it has shown its strong vitality. AC LED technology will inevitably become a direction of the development of the industry, and will revolutionize the development of the LED industry. In less than a few years, high-brightness, high-power, low-cost AC LED products will enter the market quickly, welcoming her beautiful spring!
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