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LED lighting is the key away from us how far the silicone-HongYe silicone

Writer:TcoglorSource:www.szrl.net Date:2013-04-23

Energy and the environment is a major test facing humanity in the 21st century green energy to become the focus of world attention. Lighting, for example, about 20% of the total power consumption, significantly reduce electricity for lighting is an important way to save energy. LED with its energy efficient features, and unprecedented opportunities in the lighting field.

LED light-emitting diodes, also known as light emitting diode (Light Emitting Diode, abbreviated as LED) semiconductor devices for electrical energy into light energy, belong to the solid state light source. It is a solid semiconductor chip as luminescent materials and ends with a positive voltage, the semiconductor carrier compound and release excess energy to produce visible light photon emission. Compared with the traditional vacuum incandescent light bulbs, semiconductors, LED light source with unparalleled advantages. Semiconductor LED is very long working life of more than 10 times the conventional lighting apparatus, effectively reducing the cost; it is low power consumption, high luminous efficiency, energy saving, suitable candidates for future energy strategy; the small size of the LED light source, the weight light, adaptability, and provides great flexibility for the design and application; white power LED light source is a solid light bulbs, do not need is packaged in a vacuum glass, and thus resistant to shocks and collisions; LED light source or a pollution-free mercury light source.

Especially with the LED chip technology to improve in recent years, lower prices and drive circuit mature, so that the LED light source in the field of lighting applications possible. In the increasingly tense situation in the global energy, some of the world's developed countries and regions have implemented a plan to promote the development of LED industry. LED lighting efficiency, the United States, Japan and other countries and regions were predicted, 55% of the incandescent, fluorescent LED to replace annual savings of $ 35 billion of electricity every year 755 million tons of carbon dioxide emissions can be reduced. Japan 100% of the incandescent to LED, can be reduced by 1 - 2 nuclear power plant generating capacity, an annual saving of more than one billion liters of crude oil consumption. In Taiwan, 25% of the incandescent and 100% fluorescent LED replaced by an annual saving of 11 billion kWh of electricity.

Attracted worldwide attention in 2008 Beijing Olympics and 2010 Shanghai World Expo are invariably around the green energy as the theme to the development of the LED lighting industry in China has brought great historical opportunity, according to the domestic well-known research firm, Chi Ngong Consulting (Sinotes), recently The forecast, released in the Olympics, World Expo, driven by strong Chinese LED lighting market to grow from $ 48.5 billion in 2007, rapid growth to $ 98.1 billion in 2010. Global energy shortage, the increasing requirements of environmental protection, with LED lighting technology, high brightness, long life, energy saving, green, and other significant advantages, along with the rapid development of LED technology, LED general lighting time draws near, will become the history of mankind lighting Following the incandescent, fluorescent lighting revolution.

However, replacing the traditional incandescent lamps, high-brightness white LED is still poor heat dissipation and the rate is not high light the problem, since heat directly affects the reliability of the LED, thereby affecting their life and out of the light is low directly restricts the LED the development of LED cooling and packaging of optical design study is particularly important. The key to light the rate of increase is the selection and application of the encapsulant and phosphor in addition to some of the heat from the LED chip, the energy released by the phosphor luminescent into the potting, the current high-power white LED, because of good thermal stability and optical characteristics of the silicone, the world's major LED manufacturing business, for example, Japan's Nichia. Germany, OSRAM, CREE of the United States, the Netherlands, Philips, United States, GE, etc. are based on two-component transparent silicone encapsulants for LED packaging. But silicone has good thermal stability, but low thermal conductivity, so a lot of heat will accumulate in the silicone material and lead to aging of materials, failure of a large number of reports of LED lighting products with silicone. So far, the relationship between the unknown mechanism of aging of silicone, and its molecular structure and optical characteristics do not know, the uncertainty of the material, resulting in major LED lighting company in the world today can not in their product description LED life is to make an accurate prediction, but also delayed the real popularity of LED products. Recently, the author was informed that Dr. Cai Dengke (Dortmund, Germany University of Technology), by the International Spectroscopy Journal of Molecular Structure, invited a theory: RAMAN, mid-infrared, near-infrared and ultraviolet-the visible spectroscopy. Of the PDMS silicone rubber for the characterization of of polymer optical waveguide materials, in which he detailed analysis of the relationship between silica gel and molecular structure of the optical absorption spectrum from ultraviolet to infrared. And he detailed description of the absorption spectra of silica gel in the visible range, and in this range, the absorption peaks, including its strength for accurate analysis and summary. Analysis of these data will be LED aging has a vital role, and spectroscopy to analyze the organic matter of aging is a very common method of testing, Dr Choi summarize the data, researchers from the molecular structure to accurately determine what silica gel lead to failure, and then can be fed back to the silicone material silicone molecules to further improve and enhance its reliability.

In addition, because the mechanical characteristics of silica gel and the LED chips are very different, the silicone material of high temperature will cause it to the light from the LED chip from the stripping and the ultimate impact rate. Understanding of Dr. Cai's research results, we find that Dr. Cai on this issue has been analyzed and summarized, after mechanical testing and aging tests confirm the polymerization of the silicone, he summed up a widely used blocking agent formulations for a variety of substrate, and this material can be a simple spray or spin coating in a variety of substrates, very suitable for the LED package. The results of this research has been published by the internationally renowned magazine Microfluidic and Nanofluidic.

LED packaging it comes to knowledge in the field of light, heat, electricity, polymer materials, is a comprehensive and complex subject, including packaging materials, silica gel has been the main factors to affect the LED quality and life into the indoor lighting applications still need to technical improvements. We believe With Dr Choi's findings, the LED is also not far from the real indoor lighting.
   
LED lighting can not be ignored technical details
    
led lighting in the recent leap in the development, led as green clean light is widely recognized. led light, long life, energy saving, easy application, the use of low cost, and thus will be a flood of applications in the home lighting, Osram Opto Semiconductors 2008 survey, the global annual household lighting lamp shipments of 50 billion. led light technology matures, the rapid growth of per-watt light-emitting lumen led gradually decline to lower prices. 1W led light source, for example, in the spring of 2008 the price of the price in the spring of 2006, third in the spring of 2009 will be reduced to a quarter in 2006. LED green lamps, mass market and growth in demand will be steady for several years the IC industry, the consumer electronics market, super VCD, DVD, mobile phones, MP3, after tsunami! The advantages of led lamps, high energy, long life, environmental protection can be generally recognized. led energy saving: DC drive, ultra-low power consumption (single tube 0.03 W -1 watt) electro-optical power conversion close to 100%, the same lighting effects than traditional energy sources more than 80%. led a long life: the LED light source is known as the longevity of the lamp. Solid cold light source, epoxy encapsulated, light body and no loose parts, does not exist filament light easy to burn, heat deposition, the light fades and fast drawback life of up to 50000-100000 hours longer life than traditional light sources 10 times. led environmental protection: LED is a green light, and better environmental benefits. No ultraviolet and infrared spectra, low in calories and no flicker, no radiation, and waste recycling, no pollution, no mercury element, cold light source, is safe to touch, is a typical green lighting. led light work characteristics of lighting the LED light source VF voltage is very low, generally the VF = 2.75-3.8V, the IF in the 15-1400mA; led driver IC output voltage is the VF XN or VF X 1 IF constant current in the 15 - 1400mA.led lamps led light two kinds of low-power (IF = 15-20mA) and high power (IF 200mA)), low-power led usually used to make the led fluorescent, decorative lights, grille; power led with do household lights, spotlights, underwater lights, wall wash lights, street lamps, tunnel lights, car work lights and so on. Power led light source is a low voltage, high current-driven devices, the luminous intensity by flow led the current size of the decision, the current is too strong will cause attenuation of the led light, led the luminous intensity of the current is too weak will, therefore, led The drivers need to provide a constant current power supply, in order to ensure the security of power led to achieve the desired luminous intensity. Led lighting field to reflect the characteristics of energy saving and long life, choose the led driver IC is vital, there is no good match of the driver IC unable to realize the advantages of LED lighting. led lighting design requires attention to technical details
led lamps for low-voltage driver IC requirements:

A driver chips nominal input voltage range should meet DC8-40V, to cover the needs of the application surface, the pressure, such as greater than 45V better; AC 12 V or 24 V input bridge rectifier output voltage with the grid voltage fluctuations, especially the high voltage output DC voltage will be high, the driver IC such as can not adapt to the wide voltage range, often breakdown in the grid voltage is increased, the LED light source also burned.

2, the nominal output current of the driver chip is greater than 1.2-1.5A, as lighting with LED light source, 1W led light with a nominal operating current of 350mA, 3W power LED light source of its nominal operating current of 700mA. power requires more current, led lighting optional driver IC must have enough current output, the design of products necessary to make 70-90% of the driver IC to operate at full negative output of the best work area. Full load output current drive IC for lighting small spaces, poor heat dissipation, fatigue and early failure.

3, the output current of the driver chips must be a long time constant, stable and light-emitting LED light source to the brightness does not blink; with the number of driver chips are used under the same conditions, the size of the output current to be as consistent as possible is discrete, so high-volume automated production line to be effective and orderly; certain discrete driver chips will be selected in the factory or put into the production line before the sub-file for the output current, adjust the PCB current setting resistor (Rs) of resistance size, so that similar led light brightness, constant current driver board of the LED lamps to maintain the consistency of the final product.

Driver chip package should be conducive to the rapid cooling of the driver IC chip, such as die (Die) binds directly to the copper, and a Pin is a direct extension of the package, for soldered directly to the PCB copper foil rapid thermal conductivity (Figure 1). 4X4mm a similar silicon die long by 300-1000mA current, there must be power, is bound to heat the chip itself, the physical thermal structure is also crucial.

5, the drive chip itself anti-EMI noise, high voltage ability to also relates to the led lighting products certified by CE, UL and other successful driver chip itself should be used and the beginning of the design good topology and high-pressure production process.

6, driver chip power requirements is less than 0.5W, the requirements of the switching frequency greater than 120Hz, and in order to avoid frequency interference and produce visible flicker. green led lighting to promote driver chip to the development of innovative design, LED lighting is inseparable from the driver chip, and therefore need a variety of LED light source drive IC.led lamps selection below 36V AC power can be considered non-isolated power supply, such as the selection 220V and 100V AC power should consider the isolated power supply. AC100-220V driver IC, depending on the application volume demanding, technically there are higher requirements, the more difficult countries in development. The demand for mass market of led lamps to all IC design company once again the chances of success, the rapid transformation as early as the product a chance to win a lot.

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Keywords for the information:Silicone  Silicone rubber  silicon 

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