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66 DESIGN007 MAGAZINE I DECEMBER 2022 Incorporating surface mount components directly onto a flexible circuit's etched cop- per land patterns is not unlike the assembly process used for rigid circuit boards. To maxi- mize robotic assembly efficiency and increase throughput of the flexible circuit, however, the circuit design engineer will need to provide a format that includes all features required for in-line assembly processing. ere are three primary process stages for surface mount assembly: solder paste deposition, compo- nent placement, and reflow-solder process- ing. To maximize manufacturing efficiency, automated systems developed for performing these functions are each designed to accom- modate the in-line conveyor transfer between one system to another (Figure 1). Conveyor systems, although adjustable, rely on at least two parallel edges to support and transport the circuit from one machine to another. While rigid circuit boards are easily configured for conveyor processing, handling flexible material in a production environment will require a provision for the support of the thin, film-based circuit throughout each stage of the assembly process. For the low- and medium-assembly volume applications, a con- veyor-compliant pallet fixture can be prepared to retain the individual flexible circuits during each stage of the assembly; however, products requiring high-volume assembly processing require a more efficient solution. To better accommodate conveyor handling, flexible circuits can be furnished from the cir- cuit fabricator with a temporary, rigid carrier panel backing. Figure 2 exhibits a single flexi- ble circuit assembly with a rather complex out- Flexible Circuits and In-line SMT Assembly Processing Designers Notebook by Vern Solberg, CONSULTANT Figure 1: Basic conveyorized SMT assembly line configuration. Figure 2: Flexible circuit retained in a uniform panel format.