In PCBA processing, FCT and ICT are two complementary testing methods, and the core differences are as follows:
1. Test target
ICT: Focus on physical defects at the component level and circuit level, such as open circuit, short circuit, component parameter deviation, to ensure welding quality and connectivity.
FCT: Verify system-level functional integrity, simulate actual working scenarios (such as signal processing, logic control), and detect dynamic performance and software logic problems.
2. Test method
ICT: Contact PCB test points through probes, statically measure component parameters and logic levels, support JTAG boundary scan, and have fast test speed (seconds).
FCT: Rely on external signal sources, loads or simulation software, dynamically input stimulus and collect response, require customized fixtures, and have slow test speed (minutes).
3. Equipment and cost
ICT: Expensive equipment (millions), require customized needle beds, suitable for high-reliability, high-density PCBs (such as medical devices).
FCT: Flexible equipment (integrated general instruments), fixture costs vary depending on function, suitable for scenarios such as consumer electronics where actual functions need to be verified.
4. Application scenarios:
ICT: Prioritizes early defect screening, especially for connectivity verification of complex packages such as BGA.
FCT: Cannot be replaced by dynamic functional testing (such as communication protocols, human-computer interaction) and multi-module collaborative verification.
5. Complementary relationship:
Usually ICT first and then FCT: ICT eliminates basic physical problems and reduces FCT misjudgment; FCT supplements high-level functional verification. The combination of the two can cover about 95% of defects, taking into account efficiency and reliability.
ICT focuses on "hardware connectivity" and FCT focuses on "software functionality". The choice needs to be combined with product complexity and quality requirements.
