The hottest nano ceramic becomes the perfect choic

2022-08-13
  • Detail

Nano ceramics become the perfect choice for UVC led thermal management

UVA based curing has been used in industrial applications for many years. However, the use of high intensity discharge (HID) mercury vapor lamps as UV light sources limits their scope of application, because although these lamps are effective, they are large, fragile and slow to start

technological progress has led to the rise of UV LED as a substitute for hid. LEDs use less power, operate at a lower temperature, and can immediately operate at a specific wavelength and power cycle. These features are changing the UV curing industry, from improving efficiency to providing new solutions, such as handheld curing applications, which are unimaginable for HID lamps like selling vegetables 1

and LEDs are still relatively inefficient. Only about 40% of the power entering UVA LED is converted into light, and the remaining 60% is converted into waste heat. This waste heat needs to be removed from the LED as soon as possible to prevent the LED from overheating and exceeding its maximum operating temperature. Failure to eliminate this heat may lead to deterioration of light quality and eventually led failure

unlike HID lamps, LEDs have a small surface area and relatively low temperature, which means that they can convection and emit negligible heat. The only way to remove heat is to export it from the back of the chip, through the PCB, to the heat sink, and then to the surrounding environment. In order to keep the LED chip at its optimal working temperature, the substrate material used for PCB needs high thermal efficiency

6: there are deficiencies in aluminum nitride when loading

in UVA applications, the module substrate tends to be metal substrate or electronic grade ceramics, especially high-performance aluminum nitride (AlN). In applications with higher power density, MCPCB based on epoxy resin does not have the necessary thermal properties (100w/mk, while AlN is 170w/mk), making AlN the preferred substrate

however, aluminum nitride is not perfect. The material itself is expensive and fragile, which is difficult for manufacturers. The general size of aluminum nitride is 4x4 inches (occasionally 7x5 inches). Larger sizes usually have lower yield and stronger brittleness. Even for 4x4 inches, it is not uncommon to lose 20% of production

Another problem of brittleness is to install the completed module on the radiator. Ideally, the circuit should be connected as firmly as possible to reduce the air gap between the circuit and the radiator. If the force is too large, it is easy to cause the aluminum nitride module to break when screwing the aluminum nitride module onto the radiator

obviously, if there is an alternative material with the same performance as AlN and the mechanical properties of MCPCB, it is very ideal. That choice is nano ceramics

nano ceramics have more advantages

cambridge nanotherm uses the patented electrochemical oxidation (ECO) process to transform the surface of aluminum plate into a thin layer of alumina (Al2O3) ceramics only dozens of microns thick. The alumina layer acts as a dielectric between the upper circuit and the lower aluminum. Compared with aluminum nitride, the thickness of this layer not only makes up for the relatively low thermal efficiency of alumina, but also conducts heat very effectively

the next step of the electrochemical oxidation process is film treatment, which sprays the copper circuit layer directly into the nano ceramic dielectric to further improve the thermal efficiency. Nanotherm DMS (a direct substitute of AlN for UV modules) has a composite heat dissipation performance of 152 w/mk, which is slightly lower than that of high-grade AlN. It can meet all other applications except the most demanding UVA applications

because the nano ceramic is essentially an aluminum pcb, it can be treated by mechanical method, the same as the standard MCPCB, without loss of production due to brittleness, and it can be fixed on the radiator with screws, without any risk of damage. Therefore, nano ceramics provide the best of both worlds: the thermal performance of AlN and the robustness of aluminum MCPCB

not only uva

uva is not the only field in which nano ceramics can exert their unique properties. It can also be used for UVC. The unique sterilization characteristics of UVC radiation enable nano ceramics to kill bacteria by destroying bacterial DNA to prevent reproduction, which makes UVC an ideal choice for sterilization

like UVA, HID lamps have been used for UVC although they do not have any phosphor coating. Mercury lamps are very effective for large-scale applications, such as municipal water disinfection. In these applications, if the lamp is damaged, the toxic bulb can be strictly controlled and quickly replaced before mercury may cause harm. HID lamps, like the UVA market, limit the range of possible applications

now, LED technology is creating a new market for small portable disinfection equipment, which is due to the small size, durability and low power consumption of LED. Products such as portable disinfection "magic wand" are about to be launched. Consumers can disinfect daily necessities such as smartphones, tablets and keyboards. The water disinfection device connected to the water supply pipeline can also disinfect groundwater, etc

moreover, consumer goods manufacturers can now embed UVC LED technology into their products and turn them into "self disinfecting" items. For example, the toothbrush can be disinfected by itself after being put back into the dental rack, the baby bottle can be disinfected by itself, and the bottle can disinfect the water inside through the button. There are actually infinite possibilities for such applications, which may have a far-reaching impact on public health

the growth potential of UVC industry is huge. According to ledinside, it will grow rapidly from 2018 onwards. However, the heat challenge cost of UVC LED is still expensive, far higher than UVA, which is also a challenge that this industry needs to face

the power of UVC LED is great. 1. About 95% of the variable width is converted into heat, which means that only 5% of the power is converted into useful light, because UVC operates in short wavelength. UVA operates at 380nm, while UVC disinfection equipment operates at 260nm. The challenge is that as the wavelength becomes shorter, the external quantum efficiency (EQE) of LEDs will decrease. At 380nm wavelength (UVA), the best EQE is 40%. When it reaches 260nm (UVC), EQE drops to a few percent, which means that for UVC led, about 95% of the power entering the LED is converted into waste heat, which needs to be removed quickly

in order to reduce external quantum efficiency (EQE), significant progress has been made in all these areas, including the use of bulk AlN wafers as the basis of epitaxial processes, because it has a low defect density, which increases internal quantum effects. Bulk AlN can also transmit light below 280nm, which may lead to innovative applications. Projects around quantum tunneling are exploring ways to reduce resistance, improve electron efficiency to improve electron injection efficiency, and use different chip geometries to improve light extraction efficiency

the current fact is that the application efficiency of ultraviolet light with shorter wavelength is very low, and a lot of heat is generated. In order to obtain a suitable output, a large amount of power needs to be input. This generates excess heat that needs to be removed from the led to keep the connection point at its maximum operating temperature

AlN is traditionally the only choice for UVC led. MCPCB does not have the required thermal properties, and due to the organic epoxy resin used to form the dielectric layer, they will be photodegradated by UVC. Nano ceramics are the most perfect choice at present: high thermal efficiency, durable, inorganic and cost-effective. If the problem of thermal management can be solved, the possibility of application will be huge

thermal management led: the key to UV success

LED technology is having a far-reaching impact on the UV industry. As manufacturers turn to LEDs, the cost of the printing industry is falling and efficiency is improving. The application of UVC LED is bringing a revolution to disinfection and sterilization. However, thermal management is still a core issue before thermal issues are addressed. However, one thing is certain. The unique quality of nano ceramics is of great significance for bringing UVC sterilization into daily life

Copyright © 2011 JIN SHI