As the backbone of electronic devices, printed circuit boards (PCBs) directly impact product reliability. With trends like miniaturization, lead-free processes, and high-density designs, rigorous inspection is critical to prevent defects such as poor wetting, cracks, or delamination.
Key Inspection Methods
Visual Inspection
Conducted post-solder printing, component placement, or reflow.
Identifies obvious defects (e.g., contamination, missing components) but lacks precision for hidden joints (e.g., BGA, flip-chips).
Limited by inspector expertise and unable to quantify structural integrity.
Automated Optical Inspection (AOI)
Uses cameras and LEDs to analyze solder joints via light reflection patterns.
Detects bridging, misalignment, and insufficient solder at 30–50 joints/second.
Cost-effective for visible joints (>0.5mm pitch) but ineffective for hidden connections.
Laser Testing (ALT)
Measures solder height/alignment using laser reflections.
Ideal for pre-reflow paste deposition monitoring, enabling real-time process control.
X-Ray Systems
Fluoroscopy: Captures 2D grayscale images to inspect voids, cracks, or bridging on single-sided PCBs. Fails for double-sided boards due to overlapping images.
Laminography: Generates cross-sectional 3D images by rotating X-ray beams. Detects defects in BGA/PTH joints and handles double-sided boards via vertical scanning. Operates at 30–40 joints/second but has high costs.
Optimizing Inspection Strategies
Combine visual checks with AOI for cost-effective surface defect detection.
Use X-ray laminography for critical hidden joints, despite higher expenses.
Leverage ALT for real-time solder paste quality control.
By aligning inspection methods with design complexity and defect risks, manufacturers enhance PCB reliability while balancing cost and efficiency.
