Permabond UV7220 (black) and Permabond UV7221 (clear) are epoxy resins that cure when exposed to 365nm UV light, and they can also cure with heat like standard epoxy resins, or by using a combination of the two: UV + heat.
Unlike UV adhesives based on acrylic chemistry, these cationic epoxies continue curing even when the UV light is removed, according to Permabond. This means they can cure in shadow areas. Other benefits include excellent chemical and temperature resistance, low shrinkage, reduced odour, and tack-free surfaces.
The tack-free nature of Permabond’s cationic epoxy/UV adhesives makes them particularly well suited to electronics applications such as bonding SMDs (surface mounted devices) onto PCBs, and glob top/semiconductor chip encapsulation.
In the Automotive industry they also are used for sensor sealing, lens bonding, and sealing glass-filled PBT or PBT-PC cameras. The glossy-tack free adhesive surface will not attract dust.
They are also said to have low shrinkage compared with regular UV-cure adhesives.
