Printing defines the solder deposit
A stencil deposits solder paste onto the required pads. Aperture geometry, paste behavior, board support and stencil alignment affect the result. Large exposed pads and fine-pitch packages often need specific aperture decisions rather than a direct copy of every copper pad.
Placement depends on consistent data
Automated placement uses component definitions and position data. Reference designators, side, rotation and package origin must agree with the assembly drawing. A component that appears aligned in CAD may still be incorrectly oriented if the placement conventions are interpreted differently.
Reflow is a controlled thermal process
The board and its components pass through a temperature profile chosen around the soldering materials and assembly. Thermal mass, moisture-sensitive components and temperature limits matter. A generic profile is not a substitute for evaluating the actual assembly.
Inspection has defined coverage
AOI checks visible placement and solder features within its configured program. X-ray can inspect some hidden structures. Electrical and functional tests address circuit behavior. Select the combination around the failure modes that matter to the product.
Release checklist
Verify the BOM and placement data, define all unpopulated references, document polarity, and state programming, cleaning and coating operations. Agree how first-article findings and component substitutions will be approved.