LED

In comparison to lamp systems, the single wavelength and lower power of LED do limit how and where it can successfully be used, but for applications that are suited to it, LED offers some great advantages:

• High Durability and lasts > 20,000 Hrs.
• Controller has a small form factor and can independently control multiple heads
• Last much longer than lamps leading to less continuous replacement, thereby can be more cost effective.
• Contain no mercury and consume less power ("green")
• Instant ON/OFF
• Small control box and more flexible heads (vs. fiber liquid light guides)
• Narrow wavelength which is great for applications that don’t require additional wavelengths
• Relatively stable power output throughout the life of the LED
• Relatively slower degradation when compared to conventional arc lamps

Narrow Wavelength

• Many UV curable adhesives, sealants and substrates require additional wavelengths for effective curing.

Narrow Beam Profile

• The power of an individual LED is focused on a very small area. Irradiance UVA levels similar to arc lamp systems can be achieved but only over a very small diameter (1-2mm).

Lower Optical Power

• Optical power of a UVA LED is < 20% of the comparable optical power of a typical UV lamp and is getting closer.

Typical LED Challenges

• Insufficient power for larger spot sizes.
• Insufficient intensity (over entire spot) leading to surface tackiness.
• Insufficient spectrum for effective curing and/or depth of cure.
• Commercially available adhesive suitable for lamp based systems do not always react well with monochromatic wavelength of the LED source.
• Lower speed of cure.

Whether or not LED can be used for a particular application will depend on the following:

• Availability of an adhesive suitable for the application that cures well at 365nm and doesn’t require additional wavelengths.
• Small spot size (typically no more than 3-5 mm).
• Low cure depth requirement.

LED best suited where:

• 365nm is the dominant required wavelength.
• Cure area is relatively small.
• Cure depth is low or not critical.
• Potential surface tackiness is acceptable.

Comparison Chart

	LED	Lamp
Wavelength	365nm/385nm/400nm or more	250-600nm
UVA Wavelength Availability	Single Wavelength	Multiple Peak Wavelengths
Optical Power (@365nm)	Significant development is underway to increase power efficiency	Maximum 1.3 watts
Peak Irradiance (365nm)	Maximum 8000 w/cm2	10500 w/cm2
Energy Consumption	Low energy consumption. Can be powered by universal power adaptor.	High energy requirements. Internal power supply.
Ecological Friendliness	No Mercury	Lamp contains mercury
On/OFF Time	Instant ON/OFF	4 minute warm up
Light Source Lifetime	>20,000 hours	3,000 to 4,000 hours typical
Spot Sizes	3-12mm (Significant loss of power with higher spot sizes)	Variable with light guides, light lines and accessories
Adhesive Selection	Small but growing.	Relatively large.
Substrate Selection	Heat sensitive and exacting substrates can be used such as thin film, thin plastics, foam plastic, paper, leather, etc. Minimal defect(warp, melt) of the substrate.	Same substrates can be used by selecting the appropriate filter.
Available Accessories	Few	Many
Applications	Limited due to fixed wavelengths, spot size and power.	Many applications.