Thermal analysis and thermal design of LED lamps and lanterns in China is a work to be done in the design of lamps and lanterns. According to the thermal analysis formula of LED lamps, only to reduce the thermal resistance of the heat sink to achieve the effect of heat dissipation. Thermal resistance to heat transfer capacity of the integrated parameters, the lower the value of the heat transfer to the chip chip or aluminum substrate faster. The heat transfer should be enhanced by reducing the thermal resistance, which is helpful to reduce the temperature of LED and prolong the life of the LED lamp.

One of the main failure forms of the external LED is the thermal failure due to the ambient temperature of 25. With the increase of temperature, not only the failure rate of LED increased significantly and LED decay increased, shortened life expectancy, so the thermal design is an indispensable link in the structure design of LED lamps. High power LED lamp shell protection level is generally more than IP65, the heat can not be distributed through the air convection outside the lamp. Therefore, the use of good thermal conductivity of the LED heat transfer to the shell of the lamp; select the appropriate thermal conductivity materials, such as the design of the lamp cooling directly determines the performance of the product.

The calculation method of the thermal resistance of 1.LED lamps is a work that must be done when the lamps are designed. The lamp is in the open after rising to achieve thermal stability finally, cM said heat stable state of each point is high, so heat calculation considering only the steady condition, the distribution of thermal transient is not important. Therefore, when the lamp is in the state of thermal stability, the calculation of the heat dissipation.

The theory of *LED junction temperature, unit: *C; Ta* use environment temperature units of%Rthb-a* lamp radiating parts total thermal resistance, total power: tW; PtotalLED: W; Pu* single unit LED power unit: W; unit resistance, single LED DEG CW; Chinese: a department of electrical lighting limited the general is not controllable, in addition to meet the lighting effect, so the thermal analysis of LED lamps mainly considering the heat in the lamp LED lamps, Ptrtal total power of single LED power dissipation effect should transfer in the way of heat conduction in the design before.

Can not change the resistance has been determined, finally the single LED current resistance is on the two refers to the heat transfer between the channel parameters at the temperature of 8 CW. lamps in accordance with the LED thermal analysis formula, only rely on the reduction ratio and heat transfer rate difference between the two methods, units of degrees CW. heat resistance heat lamp parts heat dissipation effect.

The following is a 16 LED (W, CREE brand XR-E Series) lamps as an example to calculate.

From the above calculation can be drawn: heat sink thermal resistance Rthb-a< 5.182CW lamps can be used in the external environment of 45C.

The heat transfer mode of 2.LED lamp structure is heat transfer, thermal radiation and heat convection. For high power LED lighting, heat conduction is the most important parameter for the ability to block the heat transfer. When the heat transfer in heat conduction way inside the object, encountered resistance is called thermal resistance; solid heat flow through the two phase of the contact interface, the interface itself shows obvious resistance to heat flow is called thermal contact resistance. Therefore, we consider the thermal resistance including thermal conductivity and thermal contact resistance. The main reason for the contact thermal resistance is that any actual contact area of two objects that appear to be in good contact with the surface is only part of the interface. Heat transfer is carried out by heat conduction and heat radiation in the gap, and the heat transfer capacity of the gas is far less than that of the conventional solid material. The thermal resistance of the contact heat flow through the interface, along the direction of heat flow temperature sudden drop, which is the need to avoid the phenomenon of lighting design.

An example is given to illustrate the method for calculating the thermal resistance of LED lamps. The basic structure of lamp as shown in the LED Aluminum Alloy closed shell, heat primarily through the support plate, Aluminum Alloy shell, and then scattered into the air through the external air convection, heat conduction, such as the other part of the convection between the aluminium substrate and the transparent glass lamp shell heat conduction, because the cooling effect is not obvious. Temporary negligible. Therefore, the total thermal resistance R heat dissipation is expressed as: R2 - LED thermal resistance of the supporting plate; R3 - LED between the support plate and the metal lamp shell. The metal shell R4* lamp thermal resistance; thermal resistance R5* lamp metal shell and the external environment of convective heat transfer.

The support plate and the metal shell two parts of the thermal resistance of Rth=1 contact resistance: ChhaAcadcJo coffee alElectronicPublishingtalk which at the conduction distance / cross-sectional area perpendicular to the 1 direction of heat flux, the thermal conductivity of materials for K.

The cross-sectional area of the radial length of L 3.1 decreases the total thermal resistance and improve the lighting effect of heat dissipation methods 3.1 reduced LED support plate and the metal shell LED to increase the support plate and the metal shell heat flow direction, the thermal resistance of the thermal conductivity of good material can reduce the support plate and the metal shell two parts.

3.2, LED increased between the support plate and the support plate and the aluminum substrate LED lamp metal contact surface pressure, make the object to highlight the part of interface deformation so as to reduce the gap and increase the contact surface; in the method of two objects at the interface of jelly have higher thermal conductivity with a heat conductive grease can reduce contact resistance.

3.3 in accordance with the requirements of the light design of the lamp shell curve, the aluminum substrate directly fixed in the interior of the lamp housing can save the thermal resistance caused by the LED support plate.

3.4 the arrangement and arrangement of the radiating ribs should consider the distance, direction and surface