It is important to consider the variables associated with the LED source and proper measurement tools in order to understand, maintain, and control the adhesive curing process.
UV LEDs with peak spectral outputs of 365, 385, 395, or 405 nanometers (nm) are increasingly being used to cure adhesives formulated to work with LEDs. When compared to broadband mercury sources, UV LEDs offer:
The impact of spectral differences should be evaluated based on the adhesive, photoinitiator package, and desired cure properties. The longer UV wavelengths typically found in LEDs have the ability to penetrate but are missing the shorter UVC wavelengths normally associated with surface cure. In adhesive applications, the lack of the shorter UVC wavelengths may not be an issue compared to the other UV applications that are dependent on the surface cure properties that UVC provides (see Figure 1).