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LED lamp heat conduction

In Electronic Infomation Category: L | on September 30,2011

Luxeon high power LED in the thermal performance significantly better than the ordinary low-power LED, the LED chip which is connected to a metal embedded chip, cooling performance is greatly improved. However, for special high-power LED lamps, or lamps for use in harsh environments, these lamps are generally in the enclosure rating IP65 above, if the shell is non-metallic (eg plastic) material, although the LED connected to the aluminum plate ( MCPCB), but the aluminum plate can not be effective if the heat conduction to the surface of the shell, then gather the heat will rapidly increase the temperature of the aluminum plate, causing the temperature is too high, increasing the likelihood of failure of the LED, the LED light failure caused by increased , shortened life expectancy.

theoretically heat lamps have many difficulties, the main difficulty is that while conduction and LED datasheet and convection heat transfer plays a role, while convection is convection in a closed cavity, the boundary conditions are very complex; transmission is through multi- layer thermal conductivity material, multi-layer interface, cross-sectional area is usually ranging, leading to the distribution of heat flow line before the calculation can be difficult to get through the analysis.

Because lighting is turned on gradually warming up, the last to reach thermal steady state, that is, when the thermal steady state temperature of the highest points, so the calculation of the heat lamps generally only consider the steady-state conditions, transient state temperature distribution is not important. Because the structure of a variety of media lights, so the actual calculation, we must solve them one by one for each medium, calculating the temperature distribution inside the lamp is very difficult, but it is not necessary. In fact the design is of concern in some parts of the temperature is tolerable temperature range, as long as the calculation of these parts of the thermal stability is reached when the temperature can be.

traditional lamp type LED package structure, usually with conductive or non conductive glue chip installed in the reflective cup or small Yun platform slides from gold to complete internal and LED price and external devices connected with epoxy resin package is made up of its thermal resistance 250 ~ 300 / W. The new high-power chips, if using the traditional style of the LED package, will lead to poor heat dissipation because of the chip junction temperature rose rapidly and LED suppliers and epoxy carbon yellow, resulting in the device accelerated decline until the light failed, or because of rapid expansion generated by the heat the stress caused by open circuit failure. Thus, for large current of high-power LED chips, low thermal resistance, good heat dissipation and low stress of the new package structure is the key technology. Low resistivity, high thermal conductivity of the material bonding the chip, the chip plus the lower copper or aluminum heat sink, and semi-encapsulation structure, accelerate the cooling; even secondary cooling device designed to reduce the devices thermal resistance. Inside the device, filled with a transparent soft silicone rubber, silicone rubber to withstand temperatures in the range (typically 40 ~ 200CC), colloids will not sudden changes in temperature cause the device to open, it will not appear yellowing. Parts and materials should take full account of its thermal conductivity, thermal properties, in order to get a good overall properties.

high thermal conductivity thermal insulation of soft silicone pad is being widely used in LED lighting, automotive, displays, computers and other electronic equipment and power industries. Seal contact with the surface structure, reducing the thermal resistance of air, have by their own thermal characteristics, maximum heat transfer technology to meet the requirements of the device, the device used to enhance the power and durability; 160 high temperature for several hours under the conditions of continuous testing, stable performance for a variety of LED lamps cooling needs.

soft silicone thermal interface materials, heat insulation pad is in one of the sheet material, according to the heating power devices cut any size and shape, has good thermal capacity and insulation properties, its role is filled radiator heating power devices and the space between the alternative to thermal grease, thermal paste plus mica (insulation) dual cooling system, the ideal product. Thickness 0.5-5 mm range, special requirements may be increased to 12 mm, and has passed the SGS, RoHS standards and UL safety test.

soft silicone thermal pad is a very good thermal insulation material, but also because of its particularly soft, specifically to take advantage of the gap heat transfer design production to fill the gap, complete heating and cooling parts of the area of ??heat transfer, increase the thermal area, but also play damping, insulation, sealing and so on, to meet the miniaturization, ultra-thin design requirements, is extremely use of technology and new materials. Thickness of the wide scope of application, particularly suitable for automotive, displays, computers and other electronic equipment and power industries. Especially in the non-fan cooling design, thermal silica film due to soft good thermal insulation is strong, have a certain flexibility, the heat on the chip, such as the use of soft silicone thermal film products has lead to the shell by metal cooling, very easy to use.

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