LED lighting why heat, how to solve the problem of LED life

First, on the origin of LED heat:

LED is the core of the PN junction, so it has the general P-N junction I-N characteristics, namely the forward conduction, reverse cut, breakdown characteristics. In addition, under certain conditions, it also has luminescent properties. Under the forward voltage, the electrons are injected into the P region from the N region, and the holes are injected into the N region from the P region. Each part of the minority carrier into the other region and the majority of the carrier recombination and light, and its current high-power LED luminous efficiency of about 30%, the heat will be 70%, the need for its heat treatment.

The relationship between the junction temperature LED of the TJ and the lifetime when the brightness is 70%

TJ (c) Life (H) TJ (c) Life (H) TJ (c) Life (hours)

75390008034000150 6000

65540007046000120 11700

55750006064000110 15100

451070005090000100 19500

351570004012900095 22300

252340003019100090 25700

From the chart we can see the importance of a direct impact on the temperature, it is particularly worth mentioning is that the material for cooling the heat balance speed of importance, cause the light heat without effective treatment due to serious optical attenuation. Now many manufacturers of high power LED heat sink cooling shell application of different basic aluminum alloy material, its thermal conductivity is different, some materials cooling speed is difficult to meet the working conditions of LED.

Aluminum substrate and conductive silica gel can not be ignored, thermal link grease materials, the actual life of the quality of materials used, will directly affect the LED industry with cooling conditions. How to reduce the intermediate link, directly with the heat sink close contact heat will quickly reach the balance of effective heat dissipation, is now the high quality LED lamp product development need to test the direction of the filter.

Two, heat dissipation material and heat dissipation method

Sheet metal heat transfer coefficient

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4294013172378067

Thermal conductivity unit: W/m.K, said the cross-sectional area of 1 square meters along the axis of the axial distance of 1 meters from the temperature of 1 Kelvin

The heat transfer power (K= +273.15), the larger the value, the faster the heat transfer rate of the material, the better the thermal conductivity.

Cooling method

1 get low thermal resistance and low junction temperature

2 good heat dissipation material.

3 heat dissipation area is proportional to the heat dissipation.

4 the entire heat dissipation path no bottle.