With opaque materials, a greater percentage of light gets absorbed or reflected with each unit of substrate thickness penetrated. By its very nature, an adhesive to be cured tends to be sandwiched between two materials, both of which may be opaque. The manufacturer must somehow get enough light to the adhesive to cure it, while keeping the heat low enough to avoid thermal damage and using as little energy as possible. Pulsed UV curing brings together the requisite energy efficiency and depth of penetration. Whereas a continuous mercury lamp will deliver most of its energy as heat near the surface of an opaque substrate, light from a pulsed lamp penetrates much farther into the substrate before being totally absorbed or reflected.
Pulsed light is thus more effective at delivering light energy for curing where it is needed most.
Most UV curing today is carried out with standard mercury-vapor lamps that must be left on continuously. For many applications, the warm-up time and mechanical shielding necessary for the noncuring phase of the cycle for these lamps can result in undesirable process constraints. With pulsed systems, processes can be repeatedly started or stopped with the pressing of a button or sending of an electronic signal. This greater degree of control can translate to process improvements and to significant savings in time and lamp maintenance on high-volume manufacturing lines. It is also safer for the lamp to be completely off when not curing.