Automated optical inspection

Automated optical inspection (AOI) is an automated visual inspection of printed circuit board (PCB) (or LCD, transistor) manufacture where a camera autonomously scans the device under test for both catastrophic failure (e.g. missing component) and quality defects (e.g. fillet size or shape or component skew).

It is implemented at many stages through the manufacturing process including bare board inspection, solder paste inspection (SPI), pre-reflow and post-re-flow as well as other stages.

[1] Historically, the primary place for AOI systems has been after solder re-flow or "post-production."

[2] AOIs for a PCB board with components may inspect the following features: AOI can be used in the following locations in the SMT lines: post paste, pre-reflow, post-reflow, or wave areas.

[citation needed] In many cases, smaller circuit board designs are driving up the demand for AOI vs in-circuit testing.