What method can reduce the LED decay?

To improve the temperature characteristics of LED light source can reduce LED decay

1 why to improve the temperature resistance of LED light source

Because after the LED fever after multiple resistance and high temperature radiator channel, meet 30-40, low heating radiator, low-temperature heat source in natural cooling conditions the cooling efficiency is very low, because LED heat by convection and radiation of heat to the air, if the LED radiator temperature and the ambient temperature is very small, then increase the radiator area the change of heat dissipation effect. Theoretical study shows that the radiation heat loss is proportional to the temperature of the 4 side: Q= epsilon S (T w 4 - T0 4), the greater the temperature difference, the more heat emission. That is, the higher the temperature of the radiator is, the more heat it emits. Therefore it is possible to improve the radiator temperature control, LED light source in the long steady light effect is no big change without attenuation principle. The design ideas for improving high temperature LED light source that is not only the balance of heat dissipation and cost considerations, but also enables the LED light source in high temperature safety work without light. It can not only reduce the amount of the heat sink and cost, but also can increase the bearing capacity of the working current of the chip, at the same time to reduce the LED decay to prolong the service life, is fully staffed design revolution.

2 how to make LED light source withstand high temperature

Since the advent of LED, the industry paid a huge investment to study LED decay. LED heat affects everyone engaged in LED nerve, trying to do a lot of ways, including:

Flip chip technology: flip chip technology as early as 10 years ago, foreign companies invested heavily in research, to free substrate glue grain direct welding technology, not only from the flip chip on the surface of wire is fatal, but also through direct welding technology to reduce the thermal resistance of high temperature tolerance, let light, the industry generally believe that LED is a cutting-edge technology package. But people have to ask: after many years of research, why the flip chip technology can not replace the formal chip technology and become mainstream? The basic reason is: flip early process depends not only on the ceramic substrate, but also on aluminum (copper) as substrate, (two) after soldering to withstand the high temperature of 280 degrees, will cause damage to materials and components. Compared with the metal substrate, the reflection rate of the ceramic substrate is not high, and the transient light effect is difficult to improve, and the thermal conductivity of the ceramic substrate and the contact area of the chip are limited, which also determines the stable light effect is difficult to improve. Processing and installation are not as good as the metal substrate is simple and convenient, flip process two times and double resistance soldering ceramic substrate + aluminum substrate is sufficient to offset the advantages of lazy to do. In addition, the flip chip process hot pressing welding, reflow soldering equipment and other expensive, and not mature, the future of the future of the LM flip chip technology value, that is, the first efficiency of light, the price is king. So caused a small factory wait and see, Dachang product promotion difficult embarrassing situation. Flip chip technology in the future direction of development is a mirror aluminum COM marriage, two is a fluorescent film grafting.

Phosphor away from chip technology

The fluorescent powder and potting glue tightly wrapped the chip, which seriously affected the heat dissipation. Let the fluorescent powder away from the chip, can reduce the thermal resistance of the light source package. The international patent technology of fluorescent powder and chip separation up to two hundred or three hundred, but the market has not seen this kind of products come out, the reason is the difficulty of this technology is to change the dielectric refractive matching fluorescent powder from the chip, and the chip with bare gold is also the technical difficulties of how to get the door. At present, some factory fluorescent film in small power light source experiment, but the manufacturing process and material corrosion resistance is not yet mature, the fluorescent powder from the chip technology can not only reduce the thermal resistance of light source, it is more important to glue mixing, vacuum, baking and other miscellaneous packaging factory in the process to get rid of. Once the breakthrough will undoubtedly be a change in the pattern of packaging technology revolution.

Liquid cooling technology

The method of cooling the chip into the coolant is to allow the LED to be immersed in a transparent conductive liquid. Heat transfer and dissipation due to the heat transfer of liquid. As long as there is a temperature difference between the chip and the heat conducting fluid, the heat exchange is never stopped. It can greatly reduce the thermal resistance of the package, is a very good design ideas. Many experts at home and abroad have proposed this method, the number of patents. However, in the actual design, it is very difficult to inject the liquid in a small package space, and it is subjected to high temperature and low temperature and no leakage.

Using integrated (COB) package, compared to a number of small power array, because the light intensity and heat dissipation in parallel, can increase the intensity / thermal resistance ratio.

The leather is used to remove the adhesive from the substrate and the leather, and the leather is used to remove the high temperature resistant material of the dam glue, and the temperature resistance of the light source is improved.

To reduce the total reflection light path optimization, the angle of light, LED light source light that improve efficiency, reduce the heating system.

It can improve the steady state light efficiency and transient light efficiency ratio.

Lens loss reduction.

Reduce the light loss protection component.