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UV curing technology is utilized for drying inks, coatings, adhesives and other UV sensitive materials through polymerization. UV LED improves on that existing process by enabling thinner, heat-sensitive substrates while reducing harmful byproducts such as ozone, and improving workplace safety. Additionally, UV LEDs can be turned on and off instantly, and utilize input power efficiently to enable lower operation costs over the application lifetime.
LED UV Curing technology uses Light Emitting Diodes (LEDs) which are semiconductor devices that emit light with a specific peak wavelength when electric current is passed through them. As with all semiconductors, the technology associated with production has rapidly improved in recent years, resulting in products that emit much brighter light and are available over a broader wavelength. LEDs are beginning to replace conventional light bulbs in many illumination applications.
The majority of LEDs are supplied with the active semiconductor mounted on to leads and moulded into a clear plastic package. This limits how closely they can be packed together. For example with 3mm diameter parts it is only possible to fit nine in a 1cm2 area. However, the bare semiconductor (known as a die) is a very small, ranging from 0.3mm x 0.3mm to 1mm x 1mm, and this enables up to 200 devices to be assembled into the same area while allowing space for the electrical connections. More densely packed devices result in higher intensity light output.
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However, it is not that simple!
LEDs are around three to four times more light efficient than bulb technology with 15 - 20% of the applied electrical energy being converted into light. Unfortunately, this means that 80 to 85% is transferred into heat. Increasing the packing density of the LEDs increases the heat density generated and complicates the thermal management system required to keep the LEDs cool.
If LEDs are allowed to get too hot their life will be significantly shortened. Water cooling is probably the most efficient method of removing the heat. Forced air cooling can be used but this reduces the density of LEDs that can be thermally managed hence reducing the radiant flux density (light intensity). Reducing the density even further will allow simple heatsinks and natural convention cooling.
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