With this system, a drop of adhesive is used to form a bridge between the component or wire, and the substrate. Exposure to UV light quickly cures them, and holds the component in place. Useful applications for NEA 121 and 123 include wire tacking, chip capacitor bonding, coil termination, bonding of head gimbal assemblies and tamper proofing adjustable components. The unique advantage of these adhesives is that even though they cure in seconds, they are extremely stable when not exposed to ultraviolet light. Norland 121 and 123 are sensitive to the whole range of UV light from 320 to 380 nanometers with peak sensitivity around 365 nanometers.
Cure time is dependent on light intensity and thickness of adhesive layer.
The adhesives have been designed to be spot cured in small areas with hand held or desk top UV light sources that are safe and easy to use. These are most commonly used in conveyorized applications because the light must be shielded from the operator. These types of lights are available from companies such as American Ultraviolet or Fusion UV Curing Systems. In addition to the UV cure, Norland 121 and 123 contain a latent heat catalyst that can quickly cure areas that do not see the ultraviolet light. Faster cure times are possible with infrared ovens.