Despite the potential hazards of ultraviolet (UV) light that are evident in everyday life, such as sunburn, the UV spectrum offers many benefits in a multitude of areas. Not unlike how standard, visible LEDs have impacted today’s marketplace, the advance of UV LEDs is offering a range of advantages to a diverse number of applications.
Recent technological developments are moving the UV LED market segment into a whole new level of product innovation and performance. Design engineers are taking note as emerging UV LED technologies generate significant cost, energy, and space savings compared to alternate technologies. In fact, five key benefits of the latest generation of UV LED technology demonstrate why the market is projected to grow 31% in the next five years.
Range Of Applications
The UV spectrum encompasses all wavelengths between 100 and 400 nm in length. It’s commonly broken down into three distinct subfields:
• UV-A: 315 to 400 nm (also known as long-wave UV)
• UV-B: 280 to 315 nm (also known as medium-wave UV)
• UV-C: 100 to 280 nm (also known as short-wave UV)
Dental curing instruments and counterfeit detection applications were early adopters of UV LED technology. But performance, cost, and durability benefits combined with recent enhancements in life span are causing UV LEDs to be integrated into a rapidly growing number of applications. Today, UV LED applications include:
• 230 to 400 nm: optical sensors and instrumentation
• 230 to 280 nm: UV ID verification, barcodes
• 240 to 280 nm: sterilization of surface areas and water
• 250 to 405 nm: forensic and bodily fluid detection and analysis
• 270 to 300 nm: protein analysis, drug discovery
• 300 to 320 nm: medical light therapy
• 300 to 365 nm: polymer and ink printing
• 375 to 395 nm: counterfeit detection
• 390 to 410 nm: superficial/cosmetic sterilization
UV LEDs provide several environmental benefits compared to alternative technologies. They consume up to 70% less energy than cold-cathode florescent lamps (CCFLs). UV LEDs also comply with the European Union’s Restrictions on Hazardous Substances (RoHS).
Further, UV LEDs don’t contain the toxic mercury often found in CCFL technology. They are much smaller and more durable than CCFLs and are more resistant to vibration and impact, resulting in less product breakage and reduced waste and maintenance expense (Fig. 1) as well.
Enhanced Life Span
Over the last 10 years, insufficient life spans have challenged UV LED technology. Despite its many benefits, its adoption was significantly slowed due to the fact that UV rays easily broke down the LED epoxy, degrading the life span of UV LEDs to less than 5000 hours.
The next generation of UV LED technology featured “hardened” or “UV resistant” epoxy packages that provided life spans of up to 10,000 life hours, which still wasn’t nearly enough for most applications. This still insufficient life span was further complicated by the fact that epoxy breakdown is erratic and not graceful or linear, resulting in poor performance even before the life span was completely exhausted.
In the last several months, new technology has solved this engineering challenge. For example, Lumex’s QuasarBrite UV LED technology replaces the epoxy lenses with a robust TO-46 package that has a glass lens, allowing the technology to last at least 10 times longer and providing a life span of more than 50,000 hours.
The next major challenge will come in efficiency. For many applications such as fingerprint identification (Fig. 2), medical light therapy (Fig. 3), water sterilization, and polymer curing at less than 365 nm, the output power of UV LEDs is only 5% to 8% of input power. The efficiency improves at 385 nm and above, but only to about 15%. As emerging technology addresses these efficiency challenges, even more applications will begin to adopt UV LEDs.
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UV LEDs can provide tight beam angle and uniform beam patterns. Because of the challenges in optical efficiency inherent to UV LEDs, most design engineers are looking for a specific beam angle that maximizes the output over the targeted area.
With ordinary UV lamps, the engineer has to flood the area with enough light to try and achieve the right combination of uniformity and intensity. With UV LEDs, the lensing allows for a much tighter emission angle, allowing most of the UV LED’s output to be focused directly where it is required. To match this performance, alternate technologies would require secondary lenses with additional cost and space requirements.
Cost-Effective Application-Specific Options
It’s often far more practical from both a cost and performance perspective to create UV LED solutions specifically designed for a particular application than it is to adopt standard technology to specific applications. In many cases, UV LEDs are used in an array where beam pattern and optical intensity consistency are critical across the entire array.
By having a UV LED supplier provide a fully integrated array specifically for the application, the overall bill of materials (BOM) can be reduced. The number of suppliers also can be reduced, and the array can be tested for the specific application before it is released to the design engineer.
However, it is important to make sure the UV LED supplier can provide cost-effective custom UV LED solutions specifically designed for your application needs. For instance, a supplier partner with decades of experience with printed-circuit board (PCB) design, custom optics, ray tracing, and moulding will be able to offer a host of options for the most cost-effective and targeted solution.
In conclusion, recent technical enhancements to UV LED technology have resolved issues with die stabilization and greatly expanded life span—up to 50,000 life hours. These developments, combined with their enhanced durability, lack of hazardous materials, reduced energy consumption, compact size, quality performance, cost savings, and cost-effective custom options, are making UV LEDs an attractive alternative for a rapidly growing list of markets, industries, and applications.
Richard Halliday is the director of sales and marketing at Lumex. He has worked in the electronics industry for more than 12 years, working with design engineers on customized solutions from the PCB level up to finished goods solutions.