Actually, AOI (Automated Optical Inspection) inspection after solder paste printing means using AOI equipment to check the solder paste printed on the pads right after the solder paste printing process is completed.

Why is this step necessary?
In SMT assembly, the quality of solder paste printing directly determines the reliability of subsequent soldering. Poor solder paste printing can easily cause issues such as cold joints, short circuits, or misalignment.
Therefore, after solder paste printing, AOI inspection is required to check each pad and detect problems in time for correction.

Main inspection items:

Solder paste position: Whether it is accurately printed on the pad, any offset.

Solder paste area: Whether the coverage is sufficient or if solder paste is missing.

Solder paste thickness/volume: Whether it is uniform, avoiding excessive or insufficient solder.

Solder paste shape: Whether there are defects like tails, collapse, or bridging.

Contamination and defects: Such as foreign particles on the pad or solder paste overflow.
 

The significance of AOI inspection:

Controls printing quality at the source, reducing defects during placement and reflow soldering.

Saves rework costs and improves product yield.

Enables quality traceability throughout the production process.

In short, AOI inspection after solder paste printing in SMT means using AOI equipment to automatically detect the position, area, thickness, and shape of solder paste on pads, ensuring the reliability of subsequent placement and soldering.

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