SDG #076 PCB Assembly Process using JLCPCB Paste Stencil - Soldering Techniques #04

This instalment of the Soldering Techniques series moves from iron work to stencil based paste assembly, the method most small volume builders adopt once a board has more than a handful of fine pitch parts. The workflow covers registering a stainless steel paste stencil ordered alongside the PCB, taping or jigging the board so that it cannot shift, choosing how much paste to load onto the squeegee, and achieving a single clean pass across the apertures rather than repeated smearing that fills vias and forces paste under the foil.

The practical detail is where this is most useful. Paste selection and storage matter more than most beginners expect, since separated or dried out paste is the root cause of many defects blamed on technique. Placement is done by hand with tweezers, and the video makes the point that parts only need to be roughly seated because surface tension pulls them into alignment during reflow. Reflow itself is done with a hot air station rather than an oven, so preheat, nozzle choice and airflow are discussed in terms of avoiding displaced components and uneven heating across large copper areas.

Post reflow inspection receives fair coverage as well: bridging on fine pitch pins, tombstoned passives, insufficient joints, and how added liquid flux plus a quick pass with an iron or hot air fixes most of them. Residue cleanup is the final step, with a reminder that no-clean paste still leaves flux worth removing before a board goes into service. For anyone weighing whether a stencil is worth the extra cost on a prototype order, this is a realistic look at the time saved against the setup effort involved.