UV Exposure
Photochemical hardening of photopolymer plates
Photopolymer Plate UV Exposure
UV exposure is one of the most critical stages in flexographic plate manufacturing, involving the photochemical hardening of photopolymer plates using ultraviolet light. The process consists of several sequential stages, starting with back exposure to form the floor layer, followed by main exposure using UV-A light at a 365nm wavelength to transfer the design onto the plate.
After exposure, the plates go through washout to remove uncured polymer, then drying, and finally post-cure treatment to ensure plate stability and print-readiness. At Unidots, we use the latest conventional exposure units alongside advanced Esko XPS Crystal UV LED units that deliver superior precision and control throughout the exposure process.
UV Exposure Process Stages
Back Exposure
Exposing the back side of the photopolymer plate to UV light to form the floor layer, which determines the relief depth and provides structural stability for the plate.
Main UV-A Exposure
Exposing the front side of the plate through the negative or LAMS mask using UV-A light at 365nm wavelength, where the polymer hardens in exposed areas and remains soft in masked areas.
Washout
Removing uncured polymer from unexposed areas using appropriate solvents or water (depending on plate type), revealing the raised printing design ready for press.
Drying
Drying the plate after washout at a controlled temperature to remove residual solvents or water and restore the plate to its original thickness while preserving detail accuracy.
Post-Cure
Exposing the plate to an additional dose of UV light (UV-A and UV-C) to fully cure the polymer and eliminate surface tackiness, ensuring a longer lifespan and better stability during printing.
UV Exposure Service Benefits
UV Exposure Technical Specs
| Wavelength | UV-A 365nm |
|---|---|
| Equipment | Esko XPS Crystal UV LED |
| Plate Thicknesses | 1.14mm - 5.5mm |
| Plate Types | Digital and Analog |
| Washout Methods | Solvent / Water |
