When inserting products with polarity prerequisites, listen in order that their polarity is notreversed. Roll built-in block components right after SMT. No matterwhether They are really vertical or horizontal areas, there needs to be no evident tilt. That means DFA is in full impact for one-sided and double-sided PCBs. Like https://custom-service-baseboard38160.activablog.com/30663555/considerations-to-know-about-6-layer-one-stage-led-small-pitch-display-pcb-board