What’s the key factor of UVC LED dissipation?

To make UVC LED technology better benefit mankind, as the pioneer of UVC LED deep ultraviolet sterilization industry, Lanjin launched UVC LED packaging technology series of popular science articles, share solutions, and provide more technical solutions for human healthy life.

UVC LED is popular and continuous hotting market. We all know that UVC LED sterilization effect is significant, in a certain dose and distance, only a few seconds to tens of seconds to kill common bacteria. But what we do not know is that with the hot market, a variety of UVC LED application products appeared on the market , many of which are shoddy goods, Usually the same level of UVC LED products but the actual use effect is very different.

Thermal management is the key factor to improve UVC LED lifespan.

Like any electronic component, UVC leds are sensitive to heat. The external quantum efficiency (EQE) of UVC leds is low, and only about 1-3% of the input power is converted into light, while the remaining 97% or so is basically converted into heat. At this time, if the heat is not quickly removed and the LED chip is kept below its maximum operating temperature, it will directly affect the LED chip service life or even cannot be used. It can be said that thermal management is the key to improve the UVC LED service life.

To do a good job of thermal management, the key is to reduce the welding low void ratio

Due to the small size characteristic of the UVC LED, most heat can not be dissipated from the surface, so the back of the LED has become the only way to effectively dissipate heat. At this time, how to do a good job of thermal management in the encapsulation process is very important.

Comes to thermal management on the packaging, there are two aspects, one is the material and the other is the process.

On materials, after years of development, UVC leds on the market are basically flip chips with high thermal conductivity aluminum nitride substrate solutions. Aluminum nitride (AIN) has excellent thermal conductivity (140W/MK-170W/mK), which can withstand the aging of the ultraviolet light source itself and meet the needs of UVC LED high thermal management.

On process, there are several die bonding methods on the market. The first is the use of silver paste, although this way of binding force is good, but easy to cause silver migration, resulting in device failure. The second is the solder paste welding, this way because the solder paste melting point is only about 220 degrees, after the device patch, there will be a remelting phenomenon after the furnace, the chip is easy to fall off and fail, affecting the reliability of UVC LED. Therefore, on market mostly use the third die bonding method: the use of gold tin eutectic welding. Compared with the first two solidification methods, it is mainly through flux eutectic welding, which can effectively improve the bonding strength and thermal conductivity of the chip and the substrate, and is more reliable, which is conducive to the quality control of UVC LED.

Since the materials and die bonding processes of UVC LED packaging on the market are mostly the same, why is the effect of thermal management so different? It is necessary to mention the weld void ratio.

Welding void rate simply refers to the LED chip and substrate welding process, due to the influence of the process, resulting in some areas can not be welded on, the formation of defects, in the shape of the hollow state, is an important indicator affecting heat dissipation.

In reducing the welding cavity rate of UVC LED products, Lanjin has formed a relatively advanced and perfect process technology. At present, the overall void area of UVC LED products of Lanjin is below 10%, and the single LED largest void area is below 2%. Compared with the void rate of similar products in the market, it is at the leading level in the industry, with excellent heat dissipation effect, long product life and excellent product control. Reducing the welding hole rate is a key step to do a good job in product thermal management and improve the quality and life of UVC LED.