LED lighting market is now the opportunity to heat the key material is a foregone conclusion

Recently held in Taipei Taiwan international lighting technology exhibition just ended, exhibitors Gongxiangshengju, showcased the latest application of LED lamps. Continue to expand in the global LED market on the occasion, in addition to Europe and Chinese, etc. the potential market, and do not neglect a very explosive market in India. India demand for LED products mainly rely on imports, imports in 2004 LED in India for $64 million 700 thousand, imports in 2005 has increased to $71 million 230 thousand in 2006, LED imports reached $88 million 500 thousand, the annual growth rate of more than 11.93%, to 2007 India economic development more rapidly, LED import amount highs.

After two years of development, India in 2010 is expected to more than $1 billion, the annual growth rate of 12%, is one of the global LED market is quite promising emerging markets, this is mainly the power demands of the country with the economic growth driven by the great, limited by resource, but the advance on energy saving application the layout of LED carbon, or to build more power plants is not enough.

Before the date of the Ministry of economic affairs have estimated that if the future of Taiwan 2 million 300 thousand street lamp can change LED lamp, 1 year can save 750 million kwh, and NT $1 billion 500 million for electricity, while reducing carbon dioxide emissions 517 thousand tons.

"LED street light" seriously need a fundamental LED cooling technology to solve

In technology lighting the exhibition, we see some interesting phenomena. The discovery of large lights, stage lights, outdoor display that is in some manufacturers wash wall lamp, lamp shell lamp radiating coated with a thick layer of the traditional black paint, the painting is like a LED lamp as pump motor. After that interview, manufacturers said that because is used in outdoor, to resist erosion of climate change to acid rain, spraying paint protection. Why do you want black paint? The answer is actually more resistant to dirty, dirty comparison can not see. Why paint? Don't worry about the paint will form a heat resistance caused by LED decay? The answer is that if the protective anode will have thermal resistance, and failure in a few months will be exposed, had to use paint protection, even if it will also try to get through the light engineering units is good acceptance.

Temperature actually is the key problems of LED street light, LED lights are on the card in this link. LED lamp as the light emitting power is higher than domestic lamps, so manufacturers in the design of heat dissipation substrate fin, the radiating fan is painstaking, wait until the assembly is completed and outside the lamp and radiating module with spray protection to prevent climate erosion. Unexpectedly this painting is the external protection of thermal module to dissipate the heat to row back closure, caused by poor cooling, resulting in severe LED epitaxial decay. According to the current large lamp acceptance, LED lamp life testing: the life of more than 1000 hours of testing (LifeTest), light attenuation is less than 3% (dry of light); more than 15000 hours of life test (LifeTest), light attenuation is less than 8%. Pass specification, it can not get public works acceptance.

In the LED application, terminal heat dissipation is better than the heat conduction interface layer

Industry for the heat from the thermal conductivity (HeatConductivity) and (Heatdissipation) on both sides has been cooling. For the industry in the LED heat is too much emphasis on the pursuit of the end of the heat conduction layer approach, crown product chemistry company's R & D Vice President Dr. Ye Shengwei, put forward the fundamental solution is different from the general practice of the industry.

Dr. Ye pointed out that if the import the following formula of thermal resistance of Rtotal=Rl-s+Rs+Rs-a, the LED of LED to the total thermal resistance thermal resistance between Substrate substrate (Rl-s), and substrate thermal resistance (Rs) resistance plus substrate to the air terminal (Rs-a) the sum of the three. In general aluminum substrate Rs thermal resistance of about 2~3cm2? K/W, and the substrate to the air side of the thermal resistance Rs-a heat can reach 400~3000cm2? K/W, but the bottleneck on the substrate side. When importing the formula to calculate the heat flux, heat flux q=Q (total energy) /A (surface area) = (T1-T2 difference)? K (thermal conductivity) /l (the length), due to the thermal flow Q LED constant as a constant, so the thermal resistance (Rt) by length L divided by the thermal conductivity of K values. The shorter the length of the heat conduction can effectively reduce the thermal resistance, thermal resistance and thermal resistance as the interface between the interface and the interface between the cumulative resistance and rise.

Bottleneck in the heat of the traditional aluminum substrate

Dr. Ye pointed out that the conventional MCPCB heat aluminum substrate industry, is from the bottom of aluminum block and the upper copper group, middle filling adhesive (Adhesive). The thermal resistance of the copper foil is close to 0 0.001cm2, and the thermal resistance of the aluminum substrate is 0.08cm2? K/W, but the thermal conductivity of the thermal conductivity is as high as 1cm2? K/W, and the actual measured MCPCB thermal resistance is about 2~4cm2? K/W? K/W. From the point of view of heat conduction, aluminum plate at the bottom of the traditional MCPCB is redundant, and the conductive adhesive between copper foil is usually hard material, the temperature rises because of copper and aluminum expansion coefficient caused by different intermediate heat conduction glue gap increases the interface thermal resistance layer.