Thermal management innovator Cambridge Nanotherm has announced the launch of Nanotherm DMS, a unique direct-metallised single-sided thermal management solution that addresses the challenges created by UV LED modules.
Ultraviolet (UV) light has key applications for curing resins and inks (UVA) and for disinfection and sterilisation (UVC). LED technology has transformed the industry by enabling smaller, more cost-effective and robust devices that have opened up previously inaccessible applications.
UVA LEDs are rapidly displacing traditional UV lamps in the industrial printing industry, speeding up print times and reducing cost, while UVC LEDs open up applications like portable sterilisation units that can provide millions with clean drinking water, or let you sterilise your toothbrush when you’re camping. The UVC market in particular is on the cusp of meteoric growth. Yole Développement expect the market for UVC LEDs to grow from $7 million in 2015 to $610 million in 2021.
However, UV LEDs present a significant thermal challenge. UVC LEDs often only convert five per cent of the power put in to photons. The remainder must be conducted away as heat via the base of the LED to a thermally conductive PCB to avoid the LED die overheating.
As shorter wave lengths of UV light degrade organic material the choice of PCB is often limited to inorganic materials, discounting cost-effective metal-clad PCBs (MCPCBs) that rely on an organic epoxy based dielectric layer. Ceramics such as aluminium oxide (Al2O3) or aluminium nitride (AIN) are used, but they present a conundrum to LED designers — low-performance but cost-effective alumina (25W/mK), or high-performance but expensive aluminium nitride (140-170W/mK).
There is another issue with ceramic. It’s brittle and prone to cracking, far from ideal for the new wave of portable applications and equally an issue for industrial applications — overtighten a screw and the module PCB will fracture.
Cambridge Nanotherm has developed Nanotherm DMS to address these issues. It combines the robustness and manufacturability of aluminium with the high thermal performance of AIN and as it undergoes thin-film processing, it’s entirely inorganic.
Nanotherm’s direct metallised single-sided PCB (Nanotherm DMS) uses an extensively patented electro-chemical oxidation (ECO) process to convert the surface of aluminium into an alumina dielectric layer. This nanoceramic alumina has a thermal conductivity of 7.2W/mK which, coupled with being just tens of microns thick and using a direct metallisation process, gives a composite thermal performance of 152W/mK. While this is slightly inferior to the very best and most expensive AIN substrates, the mechanical robustness of the Nanotherm metal board permits better approaches to mounting so measured system performance exceeds that of aluminium nitride.
Cambridge Nanotherm sales and marketing director Mike Edwards said: “UV LEDs are opening up incredible new opportunities for applications ranging from the life changing to lifestyle changing. The challenge for module manufacturers remains how to balance thermal requirements with cost and practicality. With Nanotherm DMS there is now an option that brings together the performance of ceramics with the robustness and manufacturability of MCPCBs and being fully inorganic it won’t degrade with use.
“Nanotherm DMS is designed to meet the extremely challenging requirements of the UV industry and offers the only alternative to ceramics on the market. We’re working with our customers on some really exciting applications that take full advantage of the unique properties of Nanotherm DMS and are looking forward to helping more.”