Improved Curing Solutions with LED Wavelengths below 365nm
Mike Kay, Excelitas Technologies
Abstract:UV LED solutions have demonstrated the ability to successfully replace older mercury lamp solutions in a number of curing applications by providing reduced operational costs through longer lifespans, reduced electrical consumption, higher reliability and reduced heating of substrates. However, in a number of applications such as UV curable coatings, there are still limitations for UV LED curing, preventing wide commercial adoption.Among the available formulations, the variation in curing performance compared to existing Hg lamp solutions can be quite large and surface cure remains the biggest challenge to overcome with LED curing. Current LED systems are restricted to wavelengths of 365nm or higher, limiting the available photoinitiators compatible with LED systems as well as eliminating the benefits of UVC exposure for improving surface cure. Providing UV LED solutions with wavelengths below 365nm, including systems with multiple wavelengths to closer match the spectral output of a Hg lamp is an attractive solution that is investigated in greater depth to explore irradiance, dose and wavelength requirements for industrial curing solutions. In addition, the feasibility of providing commercial LED curing systems at wavelengths below 365nm as well as with multiple wavelengths is also discussed.