LED lighting applications are gaining popularity, but a lack of standards is hampering their development in the industry. The DTF Taiwan LED Supply Chain Technology Forum invited Jay-San Chen, director general of the Bureau of Standards, Metrology and Inspection (BSMI) under Taiwan's Ministry of Economic Affairs (MOEA) to give a talk on the issue of LED lighting standards. Chen also revealed his related experiences in China and current cross-strait communication on the subject.Firstly, Chen talked about the LED lighting industry in Taiwan. The MOEA has introduced a green energy industry program. Its goal is to make Taiwan the leading LED light source and module supplier and create 54,000 new jobs. Hopefully, by 2015, the production value of the industry will reach NT$540 billion. In the first half of 2010, the industry generated NT$77 billion in revenues, which is equivalent to 80% of the total revenues in 2009. We expect that the total revenues of 2010 will reach NT$170 billion, with a 79% growth.China's LED lighting industry is heavily subsidized by its government under the 11th Five-year Plan, which allocated 1-1.5 billion yuan for the industry. In addition to the subsidies, the government also helped to set up production bases for semiconductor lighting and removed the non-tariff obstacles. At the same time, it also launched the Lighting Engineering and the 10 Cities with 10,000 Lights projects. It is expected that the above policies will generate 500 billion yuan in revenues and total export value of US$30 billion, and create one million jobs.As for LED lighting standards, Taiwan is working on 21 new standards and amending another. These include three standards for light sources; three for lighting devices; one for photobiological safety; 12 for components and modules; and two for key components. The priority is given to the standards for light sources, lighting devices and photobiological safety, followed by components and modules. The one being amended is CNS 15233 for "LED street lamps," and the revision has been passed and will be announced soon. We hope to gather opinions from the industry during the process of making the standards.The CNS 15233, first announced in December 2008, was the first LED street lamp standard in the world. We expect that the national standards for AC LED issued in 2010 will also be the first in the world. CNS 15233 has also been listed as an item under the CNS certification program, and the LED street lamps made by Everlight Electronics has been granted the CNS logo.In China there are 54 standards for LEDs and 45 for LED lighting. There are 28 national standards, and 71 industrial or local standards. Although it seems that China has more standards than Taiwan, most of them are on industrial levels, which are not as strict as national ones.Taiwan and China have started communication on LED standards. In the fourth meeting between their envoys, Taiwan and China agreed to jointly build a set of cross-strait mechanisms concerning standards, metrology and certification. They will cooperate in five areas: standards, metrology, inspection, certification, and consumer product safety. The MOEA's Bureau of Standards, Metrology and Inspection and China's General Administration of Quality Supervision, Inspection and Quarantine will be in charge of the work.A symposium on cross-strait certification and standards was held in Chengdu, China in July, 2009. China suggested setting up a self-evaluation certification system, and the four group discussions were organized during the symposium to touch on the issues of LED standards, LED evaluation, LED terminology, and LED certification technology. In the coming future, both parties will exchange information regularly and have closer communication. In March 2010, another symposium was held in Fuzhou, China, focusing on the issues of energy saving and new energy. The main themes were 3D displays and photovoltaics (PV). But issues concerning LEDs are expected to be included in the future.A comparison of CNS 15233 and China's GB/T 24827 for street lamps will show that they are similar in performance levels, safety requirements, power factors, protective enclosure levels, vibration and electromagnetic compatibility. The major differences are the standards for temperature cycling (not regulated in China), surge protection, endurance and beam maintenance rate.We have started our cooperation on cross-strait LED product tests, and signed a letter of intent with the Xiamen China National Center for Quality Supervision and Test of Semiconductor LED. We have begun trial runs for semiconductor LED lighting projects. Moreover, we are working with the National Lighting Test Center in Beijing to study and compare LED street lamps' optical and electrical properties. Civilian cooperation has been handled by the Industry Technology Research Institute (ITRI) and the Lighting Association, and they have made a lot progress in different fields since 2006.Jay-San Chen, director general of BSMI Photo: Digitimes, October 2010

Testing is of great importance as most problems occurring during the manufacturing process are related to ineffective testing before production. Jeff Lee, director of Chroma ATE's Integrated System Solution BU, in his analysis of the LED's light, electrical and heat characteristics, noted the key points of testing and introduced some testing methods adopted by the industry.The interaction of light, electrical and heat characteristicsLee began by analyzing the LED's light, electrical and heat characteristics that are interrelated to one another. The characteristics of light include light pattern, light quality and light intensity, and spectrum is the characteristic of light quality. The characteristics of light intensity include luminous flux, luminous intensity, radiation flux and radiation intensity. The electrical characteristics include AC, DC, silicon controlled rectifier (SCR), and electrostatic discharge (ESD). AC and DC include electrical voltage and current, and ESD involves human body model (HBM) and machine model (MM). The characteristics of heat include thermal resistance, heat capacity and heat conduction. We need to run tests in accordance with all these various characteristics.Color rendering index (CRI) is the indicator of the quality of color, and incandescent bulbs have the best CRI at 100 among all light sources. The LED's CRI is not as high in conventional CRI calculation method but the difference is minor for human eyes.Snell's law, a theory that refraction or total reflection occurs when light goes through different mediums, is another consideration in light testing. Measures have to be taken to avoid errors in testing, as in reality a luminous body would be affected by substances nearby.Different chip structures also matter. Chip structures are often upgraded in order to elevate light extraction efficiency, such as truncated inverted pyramid (TIP) that increases the luminous efficacy of red light, or surface roughening and so on.The space between chips also influences measurement. Testing of a multi-chip design would be different from a single-chip one, and the smaller the space between chips is, the higher the luminous intensity will be. The LED's light profile also matters, as the luminous intensity varies with different light profiles even though the luminous flux is the same. Therefore, re-calibration will be needed when testing emphasizes a particular factor. Light uniformity is another problem that needs to be taken care of in testing, because even if there is only one single-chip, the phosphor-excited light still may have uniformity problems and with more chips the differences will be bigger.In terms of LED's electrical property, if uneven curves occur when analyzing LED I-V characteristic due to thyristor effect, forward bias has to be raised to a certain level for the conduction of light, and vice versa, the avalanche current should also be measured.Static can cause damage to LEDs. Sometimes it is due to human contact, and sometimes static discharge from machines sends ESD pulse to the interior of the semiconductor and damages the insulation, which can cause an early disruption of negative voltage. Tests should be done to detect any damage; otherwise LED devices will suffer attenuation as time goes by.In addition, as the LED changes with different materials due to the band gap, wavelength will be different as the band gap decreases with higher temperature.Reference for measurementThe standard for luminous intensity measurement is CIE 127:2007. The included angle will be smaller when measured from a distance, and the specimen under testing will be closer to the point source. Different standards should be adopted for different light-emitting areas. It should also be noted that light is the strongest around the optical, instead of mechanical center of the specimen under testing.The calculation of luminous flux, if done at every angle with a sensor, is very time-consuming and costly, so it can be calculated by using integrating sphere. As the distance and size of partial flux's opening will affect test results, there are strict rules in this regard. In addition, illuminance can be worked out with relative area figures when measuring radiant flux density and irradiance.The measurement of electrical characteristics is under the influence of thyristor effect that was first used by the US military and applies to all PNPN semiconductors because LED phenomena are similar to thyristor's. The reference standards in use now are: MIL-STD-750E Method 4026.3: Forward recovery voltage and time; and Lumileds' Application Brif AB22 Test Conditions For P3 series TS AlInGaP LED Chips.ESD requires various tests in accordance with the causes, and MM is used to simulate the electro-static discharge protective ability when the machine touches the components in the fabrication process. The standards include ESDA STM5.2, JEDEC EIA/JESD22-A115 and Q100-003-Rev-C. HBM simulates the components' electro-static discharge protective ability to human bodies, or the human bodies' to the components. CDM simulates the components' protective ability against ground discharge. All these have their own standards.Jeff Lee, director of Chroma ATE's Integrated System Solution BUPhoto: Digitimes, October 2010

LED heat dissipation is a much more serious issue than thermal conductivity to the extent that it remains a major bottleneck for systems so far. With in-house developed technology, TeamChem has invented a flexible ceramic thermal conductive adhesive to replace traditional thermal conductive adhesive and the anodizing process. Todd Yeh of TeamChem's R&D unit elaborated on the problems of thermal conductivity and heat dissipation as well as applications of the company's products.Thermal conductivity and heat dissipationThermal conductivity and heat dissipation are just like traffic problems. Germany has a relatively big population. The country has a sizeable population in its suburban areas partly because there is no speed limit on its highway. However, highways without speed limit can still suffer traffic jams due to poor interchange design. Both factors have to be taken into consideration to achieve smooth traffic and better commuting experience.Thermal conductivity and heat dissipation are two different concepts. For LED, substrates act as a thermal conductor instead of a heat dissipater, since heat dissipation means spreading heat into the air. As heat dissipation is a bigger issue than thermal conductivity, the 5W and 10W thermal conductive substrates commonly seen now actually are approaching the issue in the wrong direction and often turn out to become bottlenecks.Conventional thermal management methods include fans and heat sinks. But these are not applicable to LEDs. Fans, with their problems of energy conservation and dust accretion, reduce the durability of LEDs, while heat sinks are less effective. We still need to find better solutions to LEDs' heat dissipation problem.What are the possible solutions? Should we resort to air flow, increase the surface area or reduce the mass (thickness) in order to decrease heat storage?It is generally believed that a higher k value means better thermal conductivity, but thickness is often not taken into consideration. Thermal impedance will decrease with lower thickness, and heat dissipation can only be completely achieved with low thermal impedance.For traditional MCPCB, the thickness measures more than 1,600µm, with 35µm of copper foil, 100µm of adhesive and 1,500µm of aluminum plate (their k values are 400, 1 and 200W/m-K, respectively). The thermal impedance results are 0.1, 100 and 7.5µm2-K/W, respectively, adding to a total of 1.08cm2-K/W thermal impedance. This is actually the whole picture of MCPCB's heat dissipation performance. Thermal impedance measurements of several commercialized MBPCBs range from 2-4c m2-K/W.However, as the aforementioned figures are the sum of individually-calculated thermal conductivity measurements from three different layers, problems may occur in the future if interfacial thermal impedance rises. Moreover, the substrate surface needs to be filled by liquid because it is uneven from a microscopic view. Whether the surface of the thermal conductive board (TCB) can become totally even is one problem, and aluminum plates often suffer inconsistent heat dissipation.As for heat dissipation, its measurements involve still air and moving air, as air is the source of thermal impedance. Thermal impedance in still air ranges from 400-3,000cm2-K/W, and 200-1,000 cm2-K/W in moving air. You can multiply these thermal impedance figures.LED-related applications have their own heat-dissipation characteristics. For example, as there is no moving air to accelerate heat dissipation without fans, thermal impedance will be pretty high around 1,000cm2-K/W in still air. The fact that the surface temperature of most substrates is kept below 60 degrees Celsius is also a major limitation in need of solutions. Besides, while heat dissipation does represent a bottleneck, thermal conductivity is not much a problem in comparison.A number of factors must be addressed in order to promote growth of the entire LED industry, including lower costs, simplified structures and assembly processes, and better thermal management and reliability. These can all be achieved with the introduction of new materials such as low-cost thermal conductive FPCB (while aluminum costs are four to five times higher), low-temperature-curable silver conductive adhesive, and optically clear thermosetting adhesive film.Trends in product applicationsTeamChem's flexible ceramic thermal conductive adhesive - a waterproof, antistatic and self-cleaning material with high tolerance pH range of 3-11, insulating properties, weatherability and great heat dissipation - can be used for outdoor LED lamps. According to tests by clients who are LED lamp makers, system temperature is lower than traditional treatment by 10 degrees Celsius, and 7 degrees Celsius lower than anodizing treatment. The cost is also low at below NT$90 for every square meter of TC-19E thermal conductive spray coating.Conventional LED aluminum substrate fabrication is a time-consuming and costly method using copper foil, multi-layer thermal conductive adhesives and aluminum plates before anodizing the lower part of the substrates. The new fabrication method also requires cooper foil and aluminum plates but there is only one layer of thermal conductive adhesive, and the thermosetting, high-temperature-resistant, shockproof TC-19EW coating can be easily spayed and effectively bring down the temperature. The material is also acid/alkali resistant, anti-static and can prevent dust from sticking to the surface.Other applications include large thermal conductive aluminum plates for LED TVs, capacitors, or various devices, such as motors, heat exchangers, transformer boxes and internal combustion engines, that generate heat and may be exposed to natural elements.Todd Yeh of TeamChem's R&D unitPhoto: Digitimes, October 2010

Thermal issue has always been a key part in the development of the LED industry. Polytronics Technology offers aluminum substrates as the best solution for edge-lit LED TVs. Yi-An Sha from Polytronics is optimistic about the growth of LEDs' application in backlighting and general lighting. He discussed the technological development trend of thermal substrates and analyzed the pros and cons of different technologies.The trend of backlighting and lighting marketThe market trend of LED replacing CCFL is obvious. Taiwan's top CCFL manufacturers are gradually turning their focuses to LED-related products, whose share of their revenues has reached 52%. Meanwhile, the proportion of revenues from CCFL products has come down to 42%. LED backlighting is applied to various LCD panels, using such backplanes as FPCB (screen size below 15 inches), MCPCB (screen size above 15 inches, mostly edge-type) and FR4 (screen size above 6 inches, mostly direct-type).According to DisplaySearch, the penetration rate of LED backlighting in the notebook market is estimated at 90% in 2010 and 100% in 2011. In the LCD monitor market it is estimated at 25% in 2010, 50% in 2011 and 85% in 2016. In the large-size TFT-LCD market it will reach 50% in 2011 and 80% in 2012. Now the sales of LED TVs are facing short-term fluctuations mainly because of price differences, inventory digestion of CCFL sets, and adjustments in LED-backlit product lineups.As for the cost of LED TVs, the edge type is cheaper than the direct type. In the case of edge type, to further reduce the cost of backlighting, the amount of LEDs and light strips has to be reduced. Meanwhile, the brightness of LEDs, the light extraction efficiency and heat dissipation of modules need to be improved as well. Heat dissipation can be improved by using high thermal conductive board (TCB).IEK estimates the LED lighting market will reach US$5.2 billion in 2012, and its compound annual growth rate (CAGR) from 2007 to 2012 will reach 28.5%. At present LED lighting is mainly found in architectural, industrial and commercial applications. The LED streetlamp sector now embraces the concept of Energy Performance Contracting (EPC), which came into existence amid the energy crisis in the 1970s. The proprietor does not have to pay, while the supplier earns from the price difference resulting from energy savings. For the supplier, the better their technical capabilities, the more their profits. But they need to keep considerable capital in the short term.Industrial application and technological developmentThe trends of industrial application and technological development include brightness enhancement, optical improvement, energy saving, product reliability and reduction of cost. Among them product reliability is highly related to heat dissipation. The key issue of LED heat dissipation is to provide thermal conductive media to transfer the heat from the LED to the thermal substrate and then to the thermal module. If the base area of the LED is widened, then the area of heat dissipation will increase. Power supply is needed as well. The materials for composing thermal substrates are related to three areas: copper foil electric circuits, ceramic powder plus macromolecules, and aluminum substrates. The thermal conductivity of ceramic powder is 20W/m-K, macromolecules is 0.1W/m-K, and FR4 is 0.36W/m-K.Heat dissipation materials include fused silica (SiO2), aluminum oxide, crystalline silica, silica, aluminum nitride, and boron nitride. Fused silica and aluminum oxide are low-cost, and aluminum oxide has high thermal conductivity of 30W/m-K; so they are the main stream in the market. Aluminum nitride has the best thermal conductivity of 320W/m-K, but costs are high and reliability is low.Glass-fiber thermal substrates are made with macromolecules, high thermal conductive ceramic powder and glass fiber cloth. The advantages of glass-fiber thermal substrates are their easy manufacturing process, better thickness uniformity and low production costs. Their disadvantages include: good thermal conductivity on the Z axis but bad on the X-Y plane; and serious warpage.As a kind of traditional PCB, FR4 is often used in low-power electronic components or LEDs. Its thermal conductivity is merely 0.36W/m-K, therefore lower reliability. Its disruptive voltage is around 40KV/mm and price is low. Ceramic thermal substrates are suitable for high-power LEDs or electronic components. They have thermal conductivity of 2-12W/m-K and thus are more reliable. Its disruptive voltage is around 60KV/mm, but the price is three times that of FR4.Technological development of metal thermal substrateThere are two ways to produce metal thermal substrates: the dry process and wet process. The former is processed with macromolecules through continuous injection, and no solvents are needed, which reduces pollution. The latter is simple but has lower reliability. It uses solvents for blending and its chief process is printing (screen or blade printing), which needs to be dried.Polytronics' high thermal conductive silicon film adopts the "roll-to-roll' continuous dry process. It is the only 12W/m-K thermal film roll in the world. Its dry process is environmentally friendly.Yi-An Sha from PolytronicsPhoto: Digitimes, October 2010

Power modules play a key part in power saving. TM Technology's MSI sales department senior manager Alex Hor introduced their power module solutions and analyzed its technical challenges in the future.LED lighting marketHor first explained LEDs' characteristics and the history of lighting. He stated that LEDs save energy and enable long battery life; moreover, LEDs are mercury-free, small, rich in colors, sturdy, easy-to-control, and efficient. Hor also noted that the concept of lighting emerged in the 1800s. The candle lamp was invented in 1810. Sixty years later Thomas Edison invented the first incandescent lamp, which was popular for the next 60 years before fluorescent lights became available in 1938. In 1996, the need for next-generation lighting technology gained more attention due to the issue of global warming. Additionally, incandescent lights will be prohibited in 2012, and white light LEDs will be the mainstream, with OLED being another option.The advance of LED technology has allowed LEDs to penetrate the lighting market. Red lights, yellow-green lights, and orange lights had been commercialized by 1990. GaN blue lights and green lights were commercialized in 1993 and 1994, respectively. White LEDs were commercialized in 1996. Commercialized white LEDs reached 100 l m/W in 2008. In 2009 Nichia displayed white LEDs with 249 lm/W.According to Strategies Unlimited's estimates in 2009, the luminous efficacy of cool white and warm white LEDs will reach 120 lm/W and 100 lm/W, respectively, in 2010, and 150 lm/W and 130 lm/W in 2013.Current LED lights can replace regular bulbs, candle lamps, PAR lamps, reflector lamps, mercury lamps and fluorescent lamps. Strategies Unlimited estimated its CAGR from 2008-2013 to reach 146%, 211%, 92%, 119% and 45%, with overall CAGR of 134%.Some catalysts are driving LED lights' growth. Lighting is an elementary need of human beings, but it consumes a lot of energy. The huge costs mean significantly low energy efficiency. Moreover, lighting creates a lot of carbon dioxide. Therefore, governments all over the world have announced plans to ban incandescent light bulbs during 2010-2015, and may prohibit fluorescent lights that contain mercury. But there is an issue: we are not certain whether LED lights are good enough to replace fluorescent lights.IEK has provided the reasons for robust sales of LED light bulbs in Japan. First, the luminous efficacy of warm white LEDs has increased to 97 lm/W from 83 lm/W, and cool white LEDs to 147 lm/W from 132 lm/W. Moreover, the price of LED lights has dropped from 9,000 yen to 2,000-3,000 yen. Additionally, the rise of environmental consciousness, higher electricity rates, (2.5 times that of Taiwan), recognition of LED lighting's advantages, and government support have all helped drive sales of LED light bulbs.LED lighting power solutionsWhen we analyze LED lighting's cost structure, we will find thermal components make up 30%, power supply 20%, assembly 5%, and LED components 45%, the most expensive of all. The US Department of Energy expects the price of LED light bulbs to decline 15%-20% yearly, or even faster, so that they can replace conventional lighting devices in 2012-2015.Power modules play a key role in LED lighting's power-saving. The basic requirements concern the difference in input and output voltages, maximum output voltage, efficiency under different power sources, load and temperatures. The HV LED is a possible trend; its working environment is related to its life cycle (decided by the environment) and operating temperatures. Related technologies include the measurements of PFC and driver systems. Its protection functions address power surge and over-voltage, as well as extra protection. Compatibility involves special dimming systems and ambient light sensors.There are two kinds of power module solutions: linear and switching. The advantages of linear solutions are: free from the electromagnetic compatibility (EMC) problem, fewer external components, higher current stability and smaller size. Its disadvantages are: lower efficiency, heat problems, and more restrictions on design. The advantages of switching modules are: higher efficiency and higher current stability; and its disadvantages are more external components, difficult to design, larger in size and problem with EMC. TM Technology has combined the advantages of linear and switching modules to provide four solutions: mobile solutions, switching solutions, isolated solutions and non-isolated solutions for different LED lighting markets.The challenges of LED lighting technologyLED lights have encountered many challenges, including higher prices, difficulty in designing its power management and driver ICs, temperatures, product reliability, quality and education of clients.LED lighting power management also faces a lot of challenges in terms of EMC, and the efficiency and size of power modules. For example, LED lighting modules with built-in PSR and power MOS will effectively reduce the adoption of peripheral parts and the size of the circuit. LED lighting module makers also need to consider dimming technology. Designers should weigh the pros and cons and see how they can integrate the different dimming technologies of TRIAC, ON/OFF, and PWM.Passive power factor adjustment can now reach 0.8 from the previous 0.9. The structure is simple, the price is low, and the operating frequency is the same as power supply. But passive components are big and heavy, and they have to be designed according to specific input voltage and load conditions. TM Technology can provide passive valley-fill filter to adjust its overall power factor, so that the LED driver's power factor can reach beyond 85%, in order to achieve the goal of energy saving. TM Technology's upcoming driver will adopt active power factor adjustment, with its overall power factor to surpass 95%. TM Technology expects its latest products to be more environmentally friendly.TM Technology's MSI sales department senior manager Alex Hor Photo: Digitimes, October 2010

Traditionally, LEDs are packaged on ceramic substrates, but with more and more demand for high-power LED applications, solving heat dissipation is a new challenge. That is why Visera Technologies Company is devoted to the development of silicon substrates for better heat dissipation. Yu-Hua Lee, R&D director of Visera, analyzed the heat problem and solutions for LED packaging in the DTF forum, explaining the advantages of wafer-level lens and phosphor coating technologies.Heat dissipation is critical for LED packagingLee emphasized the packaging demand for LED lighting application. The most important issue of LED packaging for next-generation lighting is heat dissipation, said Lee, estimating the heat problem could be here to stay for the next five years. And he noted another important issue in the need for a robust structure and stable materials. In addition, light performance is also important, such as the strength of the light and lighting efficiency. The last issue is the management of costs and mass production.Over the past 30 years, the evolution of LED package technology has been characterized by the shrinking of the size. However, the thermal effect is more obvious when the driving current is higher.Compared with traditional incandescent and fluorescent light bulbs, LEDs produce 20-25% radiant energy, and all is visible light. But heat conduction is up to 75-80%. The incandescent light bulb produces 95% radiant energy, of which 90% is infrared, but heat conduction is only 5%. Heat conduction of the fluorescent light bulb is 41%. Obviously LED has a more serious heat problem than the other two.The demand for high-power LEDs is rising. Heat will be produced as soon as one little LED chip is powered on. In order to reduce heat, the light's brightness has to be reduced. But at the same time, in order to increase the brightness, it needs the inputting of a higher current. However, the higher current produces more heat. And it is a circle, with heat continuing to increase.LED light efficiency drops 5% with the rise of every 20 degrees Celsius. In other words, when the temperature rises one degree Celsius, the efficiency drops 0.25%. When the temperature is at 100 degrees Celsius, YAG phosphor light efficiency would drop 20-40%. Also, the life of LED applications decreases significantly at high temperatures. With the rise of every one degree Celsius, their life would decrease 1,000 hours. Higher junction temperatures will also increase the failure rate.Generally, 90% of the heat that conventional LEDs produce moves downwards. Therefore it is a critical issue to solve the heat problem in LED packaging technology. The following data analysis reveals the importance of heat dissipation. Usually, heat conduction is the way for the internal cooling of connected surfaces at a power density of 3W/mm2. As for the external cooling, heat moves down to the heat sink through convection. If it is free convection, the power density will be 750W/m2, and if it is forced convection, the power density will be 7,500W/m2. Free convection flow may need a heat dissipation area 4,000 times as large, and it may be 400 times for forced convection. Hence, we can understand the importance of heat transfer.LED life cycle is highly related to thermal resistance. According to data from Cree, when the junction temperature rises one degree Celsius, the life of an LED will reduce 1,000 hours. If an LED works five hours per day, then the rise of one degree Celsius will reduce its life by six and half months.MaterialsMaterials for high-power LEDs sub-mount include ceramic (Al2O3, AIN) and silicon. However, silicon is the best choice for LED sub-mount materials because of its properties of thermal conductivity and thermal expansion. The thermal expansion coefficient of silicon is only at 2.6-4.0 ppm/K, which is smaller than ceramic. The thermal conductivity coefficient of silicon is 140 W/m-K, which is much higher than Al2O3 and a little bit lower than AIN. Hence, compared with ceramic, silicon is the better material for LED packaging.The thermal resistance of silicon substrates can be as low as five degrees Celsius/W, and 10-15 degrees Celsius/W for Al2O3. It seems that the resistance of silicon substrates is at least four degrees Celsius/W lower than ceramic substrates, that is to say, using silicon materials can prolong the life of LED applications by 4,000 hours.Wafer level packaging technologyThe sequence of the silicon-based LED packaging process is: isolation and metal scheme, chip/wire bond and phosphor coating, lens assembly, dicing and testing. With silicon wafers, TSV technology (single or multiple cavities) can be used to enhance light extraction efficiency, and that is what cannot be achieved with ceramic substrates.VisEra's proprietary wafer-level conformal phosphor coating technology can put a thin extraction layer of highly efficient phosphor on top of LED chips. With the innovative technology, it can improve the yellow rings phenomenon. Conformal phosphor coating can also control the consistency of color temperatures.The hemispherical lens designed to enhance light extraction is also another of VisEra's achievements. It can meet the need of every kind of light extraction.By using the phosphors compensation process to achieve tight control of color temperatures, the yield can be improved from less than 70% to above 95%.VisEra's LED lighting applications packaged with silicon-based technology have already been installed in many places, including the company's headquarters at the Hsinchu Science Park (HSP), the National Tsing Hua University campus, as well as in China's Qinhuangdao and along the JingShen Expressway.Still, many technological obstacles need to be overcome. For example, silicon materials are fragile, and mechanical strength is also a challenge. The reflection rate and the heat stability of lens - all of them are challenges for researchers. As for the structure, the isolation layer and metallization layer also pose challenges. As for the manufacturing process, phosphor coating technology and lens design are also key points that need to be addressed.Yu-Hua Lee, R&D director of ViseraPhoto: Digitimes, October 2010

Epistar was one of the pioneers that worked together with Samsung to apply LEDs in mobile phones. It is eager to expand its share in lighting market. The company's vice president, Carson MH Hsieh, gave an in-depth analysis on the trend of LED lighting, and he also discussed issues concerning LED lighting's commercialization and breakthroughs. LED lighting is the trend, but technical problems need to be overcome ETP pointed out in 2008 that if global carbon emissions have to be lowered from 62 billion tons to 14 billion tons in 2050(BLUE Map scenario). To eliminate 48 billion tons of emissions, the key point would be to improve the energy efficiency at the end-user side, which would account for 47% of the emission reduction target. Supply of renewable energy would come in second, accounting for 21%. LED lighting approaches the issue at the end-user side in line with the low-carbon economy trend. How efficient is LED lighting? In terms of luminous efficacy, incandescent and halogen devices are around 20-30 lm/W; energy-efficient light bulbs are about 70 lm/W; and HID lamps can go up to 100 lm/W; and fluorescent lights luminous efficacy has slightly improved to 120 lm/W. Although the luminous efficacy of LED and OLED lights remain at 80 lm/W and less than 30 lm/W respectively in 2010, they are improving quickly and within a few years time, LED lighting is expected to surpass conventional lighting in luminous efficacy. In lab development, we have seen luminous efficacy of LED lighting approaching 200 lm/W. Fiber to the home (FTTH) was once the talk of the town in 2000, promising opportunities for the optical communications industry. But wireless communications came along and quickly replaced FTTH, and shortly after the optical communications industry lost its momentum. We believe LED lighting is repeating wireless communications' history and will soon become the lighting for the new generation. As incandescent bulbs produce light through heat, which increases the temperature of the surrounding environment, they are not very ideal for lighting. For 20-40W lighting devices, LED has gained momentum in the market. As for 60W lighting devices, the heat issue needs to be solved first, and on top of that, LED glare remains an issue. As for lighting devices' product life, it may not need to be very long. If a product can last for 10 years or more without the need to be replaced, it would mean an end to the industry. Luminous efficacy in lm/W may not mean much to the consumers, as what really is more important is lm/$. This is the key issue, and we are aiming at 800-1,000 lm/$ to begin with. In addition, the current design for multiple light sources is very different from traditional ones. We may have to concentrate multiple light sources into one. If it is a design of lights emitting in all directions, the qualities of light - including color rendering, color temperature, lumen and the type of light - must be at least as good as traditional ones or similar to them. In practice, energy savings must be translated into money savings in 1.5 years, but there are technical hurdles to overcome. GE has recently closed its last major factory making incandescent light bulbs in the United States, a victim of a 2007 law banning sales of such light bulbs by 2014, because conventional incandescent light bulbs cannot meet the energy efficiency requirements. Furthermore, Philips also said that LED is becoming the main growing engine for lighting industry. It estimated that the market penetration rate will be more than 50% in terms of revenues in 2015. The pioneer Japanese market has already reached 50%. Technology trend for commercializing LED lighting There is no doubt that LED lighting is the future, but making LED lighting devices can be difficult, because there is no universal standard and technology is still being developed. Moreover, the optical communications industry and LED lighting industry are two different sectors, and it takes time and effort to put them together. For example, in the world of lighting, family run businesses are common and usually passed down from one generation to the next, and the proportion of in-house production is high. It is an eco-system with many "local kings" who are still reluctant to enter the LED lighting market, or have invested minor sums to test the waters. LED lighting devices form a very competitive market, and there is room for improvement regarding different standards and sales channels are still limited. Most of the producers have yet to make profits. The popularity of LED lighting definitely hinges on pricing. The current retail price of an LED bulb may stand at US$20, but an incandescent light bulb only costs US$1.5. We expect the penetration rate will be 4% when the price is cut to US$15 per bulb, 10% at US$7.5, and 25% at US$3.75, which is 2.5 times the price of an incandescent bulb. Epistar believes LED applications have no boundaries. We were the first company to work with Samsung and introduced LEDs in mobile devices. Nowadays, we can find that 50% of the notebooks on the market have adopted LED technology. Epistar was the leading company in adopting LED technology in TVs, when Korean peers were still lagging behind. Lighting will be our next focus. Why does LED lighting cost so much? The answer is in the cost structure. Cooling and metal bonding have the highest shares of the costs, while LED drivers come in second, followed by LED bin sorting. People may usually attribute the high costs to the high prices of LED chips, but LED chips in fact do not cost a lot. Their share of the production costs is even smaller than that of phosphor, whose prices are increasing. Take 800 lm light bulbs for example. The luminous efficacy is 100 lm/W in 2010, with 0.5 in luminous efficiency (0.5 for heat); driver and optical efficiency is both 80%; and Delta T is 106.3. Based on the above data, the input power is 12.5 W. If all the factors above are to be improved year by year, by 2015 the luminous efficacy will be 150 lm/W and luminous efficiency will be 0.75 (0.25 for heat). The input power will be 6.6W, and the heat it generates is less than 2W (6.6x25%), which means that cooling will not even be an issue in the future. Another concern for LED lighting devices is the actual use. For consumers, all they need to do is switch on or off the lights. Therefore, the development of AC LED technology is crucial. However, the bridge rectifier for AC LEDs is more costly, so we transform the integrated single-chip to a single chip with an external bridge rectifier diode, making it an HV LED which can endure high voltage and low current (no adopter needed). On top of that, without the internal bridge rectifier, the emitting area has increased. It suits both AC and DC. Not only does it save energy, but it is also more economical. It also supports the original design for dimming current. Epistar's high brightness blue HVLED is an InGaN LED, whose brightness has improved by 20%. The high brightness red HVLED is an AlGaInP LED which can greatly narrow the gap between warm and cold lights from the original 30%. Epistar's goal is to reach 130 lm/W in 2010, and over 150 lm/W by 2012. We believe that cooling will not be an issue by then. Epistar vice president Carson MH HsiehPhoto: Digitimes, October 2010

LED-backlit LCD TV (LED TV) shipments have seen a ten-fold increase in 2010, and growth is estimated at 2.4 times in 2011. Massive demand has driven down LED costs, and as LED luminous efficacy is expected to reach 150 lm/W in 2012, a further slide in cost is widely anticipated. Meanwhile, as the problem of heat dissipation will soon be effectively resolved, reliability and product life of LEDs will also increase as a result.While LED technology is maturing, its application market will also expand gradually with the LED lighting segment getting most attention. As global warming has become the hottest issue and energy conservation an irreversible trend nowadays, adoption of high-efficiency lighting equipment will help save massive amounts of energy since lighting accounts for 19% of all electricity consumption. Meanwhile, major countries' decision to phase out incandescent bulbs will also trigger a replacement cycle for bulbs.LED lighting prices are still much higher than those of conventional lighting now, but according to estimates by Japanese experts, LED lights will become more economical than incandescent bulbs in 19 months (electricity fees included). A further slide in prices will bring more advantages to LEDs on its way to replace traditional lighting.Besides an upgrade in technology, another crucial link necessary for LEDs' application in the lighting market is standards. This is why the DTF's Taiwan LED Supply Chain Technology Forum 2010 invited Jay-san Chen, director general of the Ministry of Economic Affairs' (MOEA) Bureau of Standards, Metrology and Inspection, as the opening speaker addressing the progress of Taiwan government's promotion of LED standards. Taiwan Lighting Fixture Export Association Chairman David Chang also made a speech in the forum, offering insight into the competition and cooperation between the island's conventional lighting sector and LED industry from a lighting vendor's point of view.On the technical front, heat dissipation remains the biggest bottleneck for LED packaging. Therefore, VisEra Technologies Company, Polytronics Technology Corporation and TeamChem Company were invited to present their optimized heat dissipation solutions in the forum. Meanwhile, TM Technology and Chroma ATE Inc shared their expertise on power module and testing, respectively, with forum participants, while Epistar Corporation, Taiwan's leading LED chip manufacturer, explored the commercialization of LED lighting and presented its state-of-the-art solutions.Taiwan steps up pace to establish LED lighting standardsTaiwan's LED industry has become the world's number-one in terms of output, and its output value also ranks second around the world. Due to a lack of common standards, however, lighting vendors still have no basis to rely on when developing products, so the government is accelerating the pace to decide on a set of standards. The standard CNS 15233, made public by the MOEA in December 2008, became the world's first set of standards for street lamps, and the AC LED national standards is also expected to become the first of its kind around the world this year. With cooperation and promotion among the industry, the government and the academic community, it will not be long before LED lighting grows into a full-fledged market.Among all its number-on titles for different industries, Taiwan was dubbed "the kingdom of lighting" 30 years ago. An integrated supply chain composed of both upstream and downstream vendors was the main reason for the fast development of the island's lighting industry back then. As Taiwan's LED industry is also equipped with an integrated supply chain now, lighting vendors are looking forward to another round of boom for the industry.However, lighting and photonics are two totally different industries where scores of cultural differences exist. For example, lighting companies are mostly family businesses supported by apprenticeship or father-to-son succession that is rare in the photonics industry. Therefore, there is still a long way to go for the two industries to achieve further integration.Moreover, LED applications in lighting still need to conquer the problem of conflicting characteristics. For example, the characteristics of LEDs include lower beam and higher luminance of point sources, lack of unified standards, fast development of products, premature performance and higher costs. However, lighting requires comfort, reliability and standardization, with higher demand for illuminance and uniformity but lower lost.Progress in LED TCB technologyLEDs face serious heat dissipation problem whether they are used in display backlighting or general lighting. Demand for high-power LEDs is rising, and high-power LEDs mean that more heat will be generated.As traditional heat dissipation tools such as fans or heat sinks are not suitable for backlighting or lighting, the development of LED thermal conductive board (TCB) technology has become an important issue.Generally speaking, ceramic substrates are the most common TCB and work well with low-power LED. Due to poor thermal conductivity, however, such substrates will suffer serious heat dissipation problems and need to be improved or simply replaced by materials with better thermal conductivity.For example, Polytronics Technology uses MCPCB substrates as its mainstream technology for applications in edge-lit LED TVs. Such Substrates are manufactured with a dry process for lesser solvent consumption, and its high thermal conductive film is made with a roll-to-roll process.TeamChem said the technological focus has been mostly on heat conductivity solutions instead of heat dissipation, which is actually the key issue. The surface of substrates is actually uneven in the microcosmic sense and needs to be filled by fluid. It may be a problem to achieve an even surface on the TCB using the traditional MCPCB technology. But it can be solved by using FPCB, a new type of flex board with great thermal conductivity.VisEra analyzed that silicon will be a better choice in terms of thermal conductivity and thermal diffusion, as aluminum substrates often suffer warpages. In addition, the thermal impedance of silicon substrates can be as low as 5 degrees Celsius/W while that of aluminum oxide is 10-15 degrees Celsius/W. As its thermal impedance is 4 degrees Celsius/W lower than ceramic on average, silicon will have an additional 4,000 hours of life in comparison.DTF Taiwan LED Supply Chain Technology ForumPhoto: Digitimes, October 2010

Micro-Star International (MSI) has announced the new 17.3-inch FX700 and FR700 notebooks featuring Intel's Core i5 processor and MSI's exclusive TDE Turbo technology.The FX700 is equipped with a discrete graphics card along with MSI's GPU boost technologies to enhance performance. The model also adopts Creative's THX high-end cinema-class wrap around sound technology to boost the audio experience.The MSI FX700 and FR700 also feature MSI's Cinema Pro technology, with which users can simply click a hotkey to instantly switch to film mode for higher resolution and richer colors. MSI FX700 and FR700 notebook specifications Model FX700 FR700 Processor Intel Core i5 Processor Intel Core i5 Processor Operating System Windows 7 Home Premium Windows 7 Home Premium Memory DDR3 1066MHz up to 8GB DDR3 1066MHz up to 8GB Display 17.3-inch HD+ LED backlight (16:9) 17.3-inch HD+ LED backlight (16:9) Graphics Nvidia GeForce GT 425M -1GB Intel integrated HD graphics Hard Disk Drive 320/500/640GB 320/500/640GB Source: Company, compiled by Digitimes, October 2010MSI new 17-inch notebookPhoto: Company

In 2010, Epson Toyocom has introduced the AH-6100LR, which is a 6-axis motion sensor, ushering in a new era of portable consumer electronics. The AH-6100LR, specialized for precise motion tracking, comprises a 3-axis QMEMS quartz gyro-sensor, and an extremely stable 3-axis accelerometer within a single packageTakeshi Miyazawa, general manager of Epson Toyocom, remarked that the company in 2004 launched its XV-3500CB angular velocity gyro-sensor that has been applied largely to digital cameras, handsets and in-car navigation systems. The AH-6100LR was developed by leveraging these technologies for high-integrity motion tracing and motion tracking applications.The new 6-axis sensor packs critical application performance features into a small package (10.0 x 8.0 x 3.8t mm). Among these features are 5,000 g of shock resistance and current consumption of just 6.1 mA, a more than sufficiently low power draw to meet the requirements of low power systems.Compared with other materials, quartz shows a high degree of stability while consuming very low power. In addition to angular rate sensors and accelerometers, Epson Toyocom continues to make better use of the characteristics of quartz material by introducing an absolute pressure sensor, the XP-6000CA.The XP-6000CA employs an innovative new QMEMS pressure-sensing structure that allows it to squeeze into a tiny 7.0 x 5.0 x 2.0t mm package yet still provides excellent total pressure accuracy (±30 Pa) and high resolution (0.3 Pa).Both the AH-6100LR and XP-6000CA have been applied to a wide variety of applications. When built into bicycles, cyclists are able to access different information as they ride such as time, speed, distance, energy consuming, route tracking, and so on. Cyclists are allowed to monitor their physical conditions during their training, and work out better solutions to avoid the impact of other external factors and reduce accident risks. Epson Toyocom will continue its dedication to developing a variety of highly accurate motion sensors that satisfy the needs of customers.The portable Seiko Crystal Chronometer QC-951, developed as a backup timer for marathon events in the 1964 Tokyo Olympic Summer Games, influenced the later development of quartz crystals and devices used for measurement and sensing. Quartz device is increasingly regarded as an essential component in electronic products where precise frequency control is necessary.Epson Toyocom Corporation was formed by integrating the operations of the Quartz Device Operations Division of Seiko Epson Corporation and Toyo Communication Equipment Co.,Ltd. in October 2005. The merged entity stays to strengthen on development of quartz components for consumer and industrial electronics applications, with products that include timing devices, sensing devices and optical devices.Manufacturing of electronics products toward weight-reduction, thin-wall and minified-size is now an inescapable trend, and constituent components need to fit in with their miniaturized designs. Therefore, the need for compact and high-precision quartz devices is increasing, and Epson Toyocom has responded to this trend with its QMEMS technology.QMEMS is a combination of "Quartz," a crystalline material with excellent characteristics such as high stability and high precision, and "MEMS" (micro electro mechanical system). QMEMS quartz devices are created using quartz material instead of the semiconductors used by MEMS. We perform precision microfabrication on the quartz material to offer high performance in a compact package.QMEMS is a registered trademark of Epson Toyocom.Takeshi Miyazawa, general manager of Epson ToyocomPhoto: Digitimes, September 2010