Can AOI automated optical inspection equipment replace ICT?
Release date:
2015-11-13 00:00
Source:
Cannot be substituted.
1. Differences in detection principles:
ICT: The In-Circuit Tester, akin to a powerful multimeter, primarily uses test probes that make contact with the test points laid out on the PCB to detect open circuits, shorts, and verify the soldering quality of all components. It can perform various tests, including open-circuit detection, short-circuit checks, resistance measurements, capacitance tests, diode testing, transistor testing, field-effect transistor testing, and IC pin inspections. Additionally, it identifies common and specialized component faults such as missing or misplaced parts, incorrect component values, solder bridging, and even pinpoint exact locations of open or short circuits on the board—clearly indicating which component is affected or where the fault lies.
The AOI inspection process for components mimics the visual inspection performed by human workers, using a ring-shaped, tower-like three-color LED light source for illumination. Light emitted from different angles—red (R), green (G), and blue (B)—as well as white (W) light created by combining these three colors, is projected onto the PCB to provide 360-degree, all-around illumination of the component being inspected. By analyzing the reflections—such as specular reflection, grazing reflection, and diffuse reflection—the system captures distinct color information corresponding to the component body, solder joints, and pads, respectively.
2. Different testing items:
ICT Testing:
A. Component failures: Over-tolerance or damage to components such as resistors, capacitors, inductors, diodes, transistors, integrated circuits, and more;
B. Soldering defects: Bridging or soldering omissions occurring after wave soldering or reflow soldering during PCB assembly and fabrication;
C. Component Placement (Mounting) Errors: Missing, reversed, or incorrectly placed components during PCB assembly and manufacturing.
D. Circuit Board Failure: Open or Broken Copper Traces on the PCB Board.
AOI Inspection ：
A. Components: Missing components, misaligned components, components standing sideways, components mounted upside down, damaged components, incorrect polarity, wrong components;
B. Solder pads: missing solder, excess solder, solder bridging, and lifted pins;
C. Solder Paste Printing Defects: insufficient solder, excessive solder, presence/absence issues, misalignment, contamination, solder bridging, and more;
D. OCR, Barcodes
