AOI vs SPI on the SMT Line
SPI (Solder Paste Inspection) catches volume and alignment before placement; AOI catches post-reflow defects. They catch different failure modes.
SPI upstream
Measuring paste volume stops defects before components are placed.
AOI downstream
Post-reflow AOI finds missing, shifted and bridged parts.
Complement, not replace
Neither sees under a BGA; X-ray still owns that.
Key Takeaways
Key Takeaways
- SPI catches paste, AOI catches joints.
- Place SPI before and AOI after reflow.
- Keep X-ray for hidden joints.
