Designing a stencil for a conventional rigid printed circuit board (PCB) is challenging enough in this day and age, but designing a stencil for a much smaller IoT rigid-flex or flex circuit takes on a considerably new meaning.
On its surface, a stencil looks a bit like kitchen tinfoil, but is made of extremely thin stainless steel and not overly flimsy like tinfoil. Based on a specific stencil design, an automated laser cuts small, specified openings on that stencil for each surface mount (SMT) component and device supporting a particular IoT product.
The stencil’s job is to serve as a guide for transferring and printing the dispensed solder paste onto the PCB. In the case of smaller IoT products, solder paste is dispensed on rigid-flex or flex circuits to solder SMT joints to a bare PCB. The pick-and-place system in the assembly process then places components and devices on to the tiny boards.
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