In printed circuit assembly, surface mount adhesives are used in both thewave soldering and reflow soldering operations to maintain component placement on the printed circuit board (PCB). Adhesive is required only between device placement and the soldering process to ensure that the surface mount or thru-hole component does not shift or lift while conveying through the assembly line or during the soldering process. The majority of surface mount adhesives used in printed circuit assembly are epoxies, although acrylic adhesives are still used for some applications.
Surface mount adhesives are cured by heat. Typically, heat cure takes place in an in-line Infrared (IR) curing oven. While the minimum temperature to initiate cure is 100°C, in practice, a typical curing profile consists of ramping to 120°C and holding for a period of approximately 5 minutes. ETS does not recommend curing SMD adhesives at temperatures exceeding 150°C as this will likely result in a brittle joint.