Reverse-Installed Capacitors Can Be Detected via Visual Inspection or ICT Testing

For polarized capacitors (e.g., electrolytic/tantalum capacitors), reverse installation is strictly prohibited. Powering such incorrectly installed capacitors will lead to rapid failure or even explosion. Thus, verifying capacitor orientation during PCB production—especially on manual assembly lines where misplacement risks are high—is critical.

Detection Methods

1. Visual Inspection (Automated Optical Inspection, AOI)

   • After soldering, PCBs are transported to an inspection station.

   • High-resolution cameras capture images and compare them to a reference standard.

   • Misoriented or wrong capacitors are flagged as defective; compliant boards proceed.

2. In-Circuit Test (ICT)

   • ICT systems, essential in modern PCBA production, detect opens/shorts and validate component placement.

   • How it works for capacitors:

     • Standard probe connections to capacitor pins cannot identify reverse installation.

     • An additional probe must contact the capacitor’s casing.

     • Polarity is determined by measuring impedance differences between the casing and each terminal (anode vs. cathode).

Why ICT Excels

• High accuracy and efficiency in mass production.

• Functions like an "automated multimeter" for comprehensive PCB testing.