Loctite 3621 surface mount adhesive is designed for the bonding of surface mounted devices to printed circuit boards prior to wave soldering. Particularly suited for applications where very high-dispense speeds, high-dot profile, high-wet strength and good electrical characteristics are required. LOCTITE® 3621 is designed for the bonding of surface mounted devices to printed circuit boards prior to wave soldering. Particularly suited for applications where very high dispense speeds, high dot profile, high wet strength and good electrical characteristics are required. Particularly suited where dispense speeds greater than 35,000 dots/h are required. LOCTITE 3621 has been used successfully in lead free processes with water and alcohol based fluxes under conditions outlined in the Environmental Resistance section.