作者：Blade

Foreign companies stationed LED commercial lighting market

Market expending of led commercial lighting

From 2010 to 2011, the two years is important time for the rapid growth and popularity of LED lights commercial lighting market. Compared with LED home lighting, commercial lighting market is more convenient in civil lighting market, sold in bulk and scale of procurement, which makes it obvious in the growth rate of the LED lighting in the LED commercial lighting market.

So far, commercial lighting is LED highest penetration rate of breakdown of lighting areas. It is easier for enterprises to accept the commercial space lighting in the price. In addition, with increasing consciousness of energy saving requirements, LED spot plays a growing role in commercial space. The data shows that commercial lighting accounts for 43% in the global lighting market of electricity consumption, which is the highest proportion. It takes 73% of the consumption for retail, office, storage purposes, educational buildings, health care applications.

Foreign companies stationed LED commercial lighting market

At present, there are about more than half of the existing LED commercial lighting needs to be replaced in the next three years. For the next decade, about 300 million people will go into cities, the city commercial lighting will further expand, which will lead to greatly prosperous situation.

Foreign companies spent a lot of money in LED market
From Guangzhou International Lighting Exhibition ended June, we can know that, besides the LED exhibiting significant increasing, another change is that LED products is gradually changing from decorative to functional. Under the baton of industrial policy, LED is getting new Pushing Hands. With the competition of foreign brands and domestic brands, the strategic change in function and decoration becomes the point. Who can take a great share finally? God knows.

Foreign brand competition is increasingly intense. Economic and Trade Commission of Guangdong Province authorities admitted that the LED market is large enough to satisfy everyone. But in another two years or even one year, it is difficult to say who will be the big boss. Indeed, China has become one of the global commercial lighting of the fastest growing market in recent years, annual growth of 20% constitutes a huge commercial lighting market. China’s lighting market have huge capacity, many brands, but it has been showing a dominant situation for foreign brand. More critical is the foreign brands use own technology, capital, sales and other advantages from epitaxy, chip, package, and application of a complete industrial chain, occupying the key areas of the market.

Mechanism Introduction for LED source

First, the light-emitting mechanism of LED lights source

with incandescent or gas discharge lamp light-emitting principle is very different. LED spontaneous luminescence is due to the compound of electrons and holes.

Mechanism Introduction for LED source

LED is formed by the  P-type semiconductor layer P and N-type semiconductor the formation of the N layer, and into the middle of the double hetero structure active layers. The active layer is a light-emitting area, the use of external power injected electrons to the PN junction under forward bias, the role of the N-zone electronic will is the direction of diffusion into the active layer, P area hole will be the negative direction of diffusion into the active layer, the electron and hole recombination will result in the spontaneous emission of light. As led source used different material, its diode electron, hole-share level different energy level high and low differential photon affect the binding energy of different wavelengths of lights, that is , the different color of light, such as red, orange, yellow, green, blue or is not visible and so on.

Second, the white LED bulbs

The emergence of the white LED provide white LED semiconductor lighting for the growing number of indoor and outdoor lighting project. The white led source luminous efficiency has made substantial progress, the white LED has even begun to challenge the status of the traditional light source.

The white LED has two main ways: The first one is to get white light through the phosphor conversion; second is to put different colors of LED chip package together with multi-chip hybrid white light. For the above two ways, according to the number of light sources in mixed white base color, it can be divided into two primary color system and the multi-primary color system.

Phosphor converted white LED

(1) two color phosphor converted white LED lamps

wo-color white LED is made ​​of blue LED chip and YAG phosphor. Generally use blue chip InGaN chip, and can also use the AlInGaN chip. The advantages of blue-chip LED with YAG phosphor are simple structure, low cost, simple production process, but there are a number of shortcomings, such as blue LED efficiency is not high enough, so resulting in  low white led source efficiency. The phosphor itself exist energy loss, and with the aging time of  phosphor and packaging materials, it also result in the color temperature drift, and shortened life expectancy.

Judgment standard for LED lighting products

LED lights industry need pay attention to develop the measurement standards

LED light-emitting surface is small, narrow beam, he characteristics of high brightness decided the particularity of detection.In order to deal with this problem, CIE set up seperately the “TC2-45 LED measurement and TC2-46CIE/ISO LED strength measure standards ” two technical committees. CIETC2-34 team held a meeting in Vienna, headquarters in October 1997, develop and recommend CIE127-1997 LED measurement standards, it involves  LED radiometric, photometric and colorimetric measurement. But because the rapid development of LED technology in recent years, especially the white LED lighting products, a lot of problems are not taken into account in the past. Therefore, the CIE at the annual meeting held in Kyoto, Japan, in 1999, proposed by the participants on behalf of the developed countries, to develop the white LED lighting equipment standards by CIETC2-34.The Japanese delegation also submitted two draft standards of general lighting with white LED.

Judgment standard for LED lighting products

In order to develop LED lighting products, developed countries have attached great importance to the study of LED spot test methods and standards. Such as theU.S. National Institute of standard tests (NIST),organizations the
international renowned testing experts to carry out the LED test, focus on studying the LED light emitting characteristics, temperature characteristics and lumen characteristics etc.test methods,and trying to establish a LED test methods of comprehensive set and technical standards. It has been walking in the forefront of the world in the aspect of LED test. Japan set up a “white LED Test Research Council, specializing in study of lighting white LED test methods and technical standards. In order to seize the developed countries in the world of high ground of the LED flood lights research, have invested a lot of manpower and resources in the LED standards and testing , the s focus on selection the parameters and testing methods of the led characteristics in the standard.

In China, there is no corresponding national standards about the semiconductor light-emitting diode test method , so often generated much controversy between different manufacturers and users . In recent years, the professional branch of the Optical Society of optoelectronic devices in succession organized academic discussions and exchanges of a number of semiconductor light-emitting diode test method,person in the industry form gradually more unified understanding, and develop a unified industry standard SJ/T2355-2005 semiconductor light-emitting diode test method, the exchange of products in the industry, played an important role in the comparison.

LED light source mechanism Introduction

Now, with the LED lights industry supply with mature, low barriers to entry, the influx of a large number of small businesses, resulting in excess of the LED industry and business capacity utilization is low, certainly competition in the market but the brand maker Philips (Philips), OSRAM Long (Os-ram) and GE, these manufacturers are actively occupying the main LED lighting market through vertical integration or strategic alliance layout. Whether it is the gross profit margin after the layers of exploitation or a powerful enemy camouflage, and thus a small factory are difficult to escape the huge market pressure.

LED light source mechanism Introduction

China has rich resources of non-ferrous metals, gallium, indium, accounting for 70% -80% of the world’s reserves, which makes the development of semiconductor lighting industry in China owning advantage on the resources. By 2010, the Chinese LED light source industry output value will be more than 150 billion yuan. Japan in 2002 cost five billion yen to implement white light, the entire project budget is 6 billion yen.

With the rapid growth rate of the penetration of LED bulbs, along with the price war arrival in 2010, because the LED is different from the traditional lamps and the light source separate from the sales model, under such pressure, some companies can not take into account quality and price competitiveness. It may fall into the acquisition or be doomed.

May 7, 2010 -12, lighting experts and entrepreneurs organize a line of Henan Province, the Illuminating Engineering Society Organization Investigation in Japan Japanese lighting the status quo, LED light source status is not satisfactory.

In recent years, the most interesting events in the lighting filed is the rise of the semiconductor lighting. In mid of 1990s, Japan’s Nichia Chemical Company Nakamura in the 20th century, breakthrough the key technologies for the manufacture of blue light-emitting diode (LED), and thus developed a fluorescent material to cover the blue LED to produce white light source technology.

The light-emitting diode is a new type of solid cold light source. The most notable characteristic is long life, high photoelectric conversion efficiency, good seismic performance, easy to use, etc. Under the same illumination, LED lamp power consumption and lifetime  have a distinct advantage than incandescent and fluorescent lamps.

LED lighting products quality explanation

In order to develop LED lighting technology, developed countries focus on the LED lights features, temperature characteristics and lumen characteristics, test methods, and try to establish test methods and technical standards of the whole set of LED. LED test has been walking in the forefront of the world.

LED lighting products quality explanation

Different applications determines the performance requirements of LED lighting products. From the point of view of optical performance, the LEDs for display, and more attention to the luminous flux, spatial distribution of the beam, the parameters of color, the color rendering properties, and biological application of LED panel is more concerned about the parameters of the biological effective radiated power, the effective irradiates. About its quality, it must be a comprehensive evaluation of many aspects of optical, electrical and thermal.

From the current structure and industrial development of LED lighting products, LED lighting products mainly consider several parameters of the optical properties, electrical properties, thermal properties, radiation safety and lifespan.

Optical properties: the optical performance of LED are mainly related to the performance requirements of the spectrum, brightness, and chroma. According to new industry standards set by “the semiconductor light-emitting diode test method “, the main parameters are peak wavelength, spectral radiation bandwidth, axial luminous intensity, the beam angle of half intensity, luminous flux, radiant flux, luminous efficiency, aromaticity coordinates, color temperature, color purity and dominant wavelength and color rendering index. The display LED are mainly visual effects, so the correlated color temperature and color rendering index is not required. and the white LED lighting, these two parameters is particularly important. It is an important indicator of lighting atmosphere and the effect, while the color purity and dominant wavelength is generally not required.

Electrical properties: LED’s are PN junction electrical characteristics, and it determines the electrical properties of LED lighting products applications, that is  one-way non-linear electrical properties, low-voltage drive, as well as sensitive to static electricity and other characteristics. The main measurement parameters include the forward drive current, forward voltage drop and reverse leakage current, reverse breakdown voltage and electrostatic sensitivity.

Thermal performance: lighting with LED luminous efficiency and power is one of the key issues in the development of LED industry, at the same time, LED PN junction temperature and shell heat issues is particularly important, generally with thermal resistance, junction temperature and other parameters.

The reason for damaged advanced led lights

High-power white LED as a new green lighting, it will own light conversion, high efficiency, low power consumption, long life, no maintenance, etc, and thus gradually being used in a variety of lighting in the area. The long life of the advanced led lights are based on a safe working environment. LED lighting is concerned. There are two threats affects their life. a electric shock over electric shock is applied to the LED on the current exceeds the maximum rated current of the LED technology in the data sheet, including over-voltage caused by over-current shock; another is overheating damage. Damage can be expressed as the immediate failure of the components that may also occur through electric shock after the incident for a long time before failure and to shorten the working life of LED.

The reason for damaged advanced led lights

The reason for advanced led lights 

The failure of LED lamps have two reasons. First, from the power supply and drive failure, the second is from the LED assembly failure. Normally, the failure from LED power supply and drive through electric shock (EOS) and the load side of  circuit failure. Input power over electric shock often cause damage to the driver chips in the driver circuit such as capacitors and other passive components breakdown damage; Load side short circuit failure may cause over-current drive of the drive circuit, drive circuit may short-circuit damage or short-circuit fault caused overheating damage.

The failure of LED components itself

Transient over-current events is to flow through the LED current to exceed the maximum rated current of the LED technology in the data sheet, which may be the direct result of the large current, and may be indirectly due to the high voltage generation, such as transient lightning switch over voltage event of power transient switching noise, power fluctuations caused by over-current. These events are transient, and shot duration, we usually referred as spikes, such as “current spikes, voltage spikes. The event caused by transient over current includes LED connected to the transient over-current power or hot plug.

For the LED lighting products in the car, ISO7637-2 transient load-dump surge impact is a major threat to their normal work.

The requirement for 12v LED lamps on the low-voltage driver chip

The requirement for 12v led lamps on the low-voltage driver led lights chip

1. The nominal input voltage range of driver chips should meet the DC 8 ~~ 40V, in order to cover a wider application needs. Pressure capacity should be greater than 45V. When input AC 12V led lamps or 24 V, a simple bridge rectifier output voltage with the grid voltage fluctuation, especially when the high voltage output DC voltage will be high.  If the driver IC does not have a wide input voltage range, often in the grid voltage is increased breakdown, and thus burn the LED light source.

The requirement for 12v LED lamps on the low-voltage driver chip

2. The nominal output current of the driver chip is greater than of 1.2 ~~ 1.5A.. As the lighting of the LED lighting source, 1W power LED lighting source, 1W power LED lighting source, the nominal operating current is 700mA. The need for greater current of the power LED street lights source, so the optional LED lighting driver IC must have enough current output driver IC design products at full load output of 70 to 90% of the best work area. Full load output current drive IC for lighting small spaces, poor heat dissipation, and easily lead to the lamps to the occurrence of fatigue and early failure.

3. The driver chip output current must be kept constant, so that the 12v led lamps can be solid light and does not blink. Driver chips in the same batch under the same conditions, the size of the output current should be as consistent as possible, so that in a high volume automated production line in order to ensure efficient and orderly. For certain discrete driver chips, the output current must be selected before the factory or put into production lines for the selection of sub-file, to adjust the current setting resistor size on the PCB,  so that the production of LED lighting keep the same with current driver board for similar LED products the light source luminance, in order to maintain the consistency of the final product.

 

 

How to select correct LED drivers IC

LED lighting will leap in the development in the near future. LED is widely recognized as a green clean light. The long life LED lights source, energy saving, easy application, the use of low-cost lighting in the home will be a flood of applications.

How to select correct LED drivers IC

In the field of LED lighting, the correct choice of the LED driver IC is essential. In order to reflect the characteristics of the LED lamp energy saving and long life. Good matching of the driver IC, the advantages of LED lighting can not be reflected. In the selection of LED drivers IC should be noted the performance indicators and how to use it?

The LED light source technology are getting mature. The per-watt light-emitting lumen rapid growth, and lead gradually decline to lower prices. 1W LED light source for example. The price in spring of 2008 is one-third of the price in spring of 2006, and it will dropped to fourth in year of 2009.

The high-energy, long life, and the environmental benefits of the superior performance of LED lamps are generally recognized.

1. High energy saving LED: DC drive, ultra-low power consumption(single tube 0.03-1W) electro-optical power conversion close to 100%, the same lighting effects than traditional energy sources more than 80%.

2. Long-life LED: LED light source is known as the longevity light. Solid cold light source, epoxy encapsulated, light body and no loose parts, it 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.

3. The LED environmental benefits: LED is a green light, the environmental benefits of better. No ultraviolet and infrared spectra, low in calories and no flicker, no radiation, and waste recycling, no pollution, and no mercury element, cold light source. It is safe to touch and belongs to a typical green lighting.

The working character of LED lighting source

The VF voltage of the LED lighting is very low, under normal circumstances is 2.75 to 3.8V, the IF is generally is 15 to 1400mA. LED driver IC output voltage is VFxN, VFx1 IF constant current at 15 ~~ 1,400 mA, LED lamps use LED light source has low power (IF 15 to 20mA) and high power (IF greater than 200mA) two kinds.

The improvement measure for saving the failure of led light system

Second, the improvement measures

LED lights described above, the main failure mode analysis, from the informed to improve the LED in the actual life of the technology.

(1)cooling technology

Cooling technology has been an important part of the LED application, LED light system can not be heat will cause the junction temperature of the chip serious rise, then the luminous efficiency of a sharp decline in reliability(eg, life, color shift, etc.) will deteriorate; Meanwhile, the high temperature and high fever will make the LED package structure of the internal mechanical stress may further lead to a series of reliability issues. Therefore, in the manufacturing process, you can choose the good thermal conductivity of the base, and makes the LED heat dissipation area as large as possible, thereby increasing the thermal performance of the device.

The improvement measure for saving the failure of led light system

(2) anti-static technology

Using the GaN chip LED, a large electrostatic will effect. If you do not deal with this problem, it will seriously affect the life of the device. In LED light system design, we should give full consideration to the design of anti-static, and to avoid device failure phenomenon caused by the breakdown of the high electrostatic voltage.

(3) packaging technology

Epoxy material that used by the package, will change because of light and temperature rise. In the use of the original transparent epoxy material browning affect the device spectral power distribution. Therefore, during the time of LED package, we should strictly control the curing temperature. Avoid to result in the premature aging of the epoxy resin.

On the other hand, in order to prevent device corrosion phenomenon we need to pay attention to the injection molding process,  the row of clean material inside the bubble as far as possible to reduce the residual amount of water vapor, reducing devices of corrosion chance, while transparent good packaging materials.

(4) optimize the manufacturing process

LED manufacturing process requires an appropriate bonding conditions, if the bond is too large, it will be crushed chips, on the contrary, the device will result in insufficient bonding strength. The LED light system device is easy to take off the loose. Therefore, to ensure that the device bonding strength at the same time. We need to try the best to minimize the damage caused by the process of bonding the chip in order to achieve the purpose of optimization of the bonding process.

 

Analysis of LED light fittings failure

In terms of the package, there is an important factor to affect the LED life is corrosion. In the use of LED lights, the general corrosion caused mainly due to water vapor infiltrated within the packaging material, resulting in lead deterioration, PCB copper corrosion; sometimes movable ions introduced with the water vapor resides in the chip surface, resulting in leakage. In addition, the package poor quality of the devices, encapsulated within a large number of residual bubbles, these residual bubbles would also cause corrosion of the device.

Analysis of LED light fittings failure

(3) thermal stress failure of led light fittings

The temperature has been an important factor of the LED optical properties, LED failure modes of the research scholars to consider the working environment temperature accelerated stress to the LED accelerated life test. This is because the LED spot lights system thermal resistance of the same premise. The welding point of the package pin temperature, junction temperature will also increase, leading to early failure of LED.

Hsu test samples provided by different vendors LED, the LED samples in the experiment were placed 80、100、120℃, 3.2V voltage drive, and provisions when the optical power of the sample decreased to the stating value of 50%, which is determined to be invalid. High power led light fittings with the accelerated life test temperature and the accelerated and the acceleration time increases and decreases.  In the accelerated life test, the LED junction temperature rise will make the epoxy material mutation, thereby increasing the thermal resistance of the system between the chip and package thermal surface degradation, eventually leading to package failure.

(4) electrical overstress failure of led light fittings

If LED tunnel used under the current circumstances or electrostatic impact damage of the chip, the chip will result in open circuit, the formation of electrical overstress failures. For example, GaN is a wide band gap materials, high resistivity. If you use such chips, the induced charge due to static electricity generated in the production process which is not easy to disappear when its accumulated to considerable extent. It can produce very high electrostatic voltage, this voltage exceeds the bearing capacity of the material occurs of the material, it will occurs breakdown phenomena and discharge, and making the device failure.