UV curing encompasses different types based on the light source, such as arc lamp and LED systems, and the UV spectrum (UVA, UVB, UVC, UVV, NUV, DUV) used to initiate chemical reactions. Additionally, UV curing can be categorized by the chemical system used, such as acrylic or epoxy-based formulations. Dual-cure methods, which combine UV with other methods like heat or moisture curing, are also used to ensure complete curing.
Types of UV Light Sources
- Arc Lamps / Mercury Vapor Lamps: Traditional industrial method emitting a broad UV spectrum including UVA, UVB, UVC, and visible light.
- LED Curing Sources: Emit a narrow band of UVA wavelengths such as 365, 385, 395, or 405 nm.
- Excimer Lamps: Serve as an alternative UV curing source for specialized applications.
Types of UV Spectrum
- Near UV (NUV): 300–400 nm. Useful for curing thicker layers.
- Deep UV (DUV): 100–300 nm. Ideal for thin layers and coatings.
- UVA (320–400 nm): Most commonly used; balances penetration and safety.
- UVB (280–320 nm): Suited for niche curing requirements.
- UVC (200–280 nm): Primarily used for germicidal applications.
- UVV (Visible Light, 400–450 nm): Helps cure white/silver pigments and deep layers.
Types of Chemical Formulations
- Acrylic-based: Cure through free radical chain reaction; commonly used for fast polymerization and cross-linking.
- Epoxy-based: Use a different chemical mechanism, offering distinct cured properties.
- Other Polymer Systems: Includes polyester, silicone, styrene copolymer, and vinyl systems.
Curing Methods
- Sole UV Curing: Ideal for rapid, on-demand curing where light can fully access the material.
Dual-Cure Systems
- UV/Anaerobic Curing: UV sets the bond initially; oxygen-free areas complete the cure.
- UV/Heat Curing: UV cures the surface, and heat completes curing in shadowed areas; used in electronics.
- UV/Moisture Curing: UV initiates bonding, moisture cures areas not reached by light; common in conformal PCB coatings.