x-ray inspection of solder
**X-ray inspection of solder** is the **non-destructive imaging method used to evaluate hidden solder joints and internal defects in assembled packages** - it is indispensable for BGA, QFN, and other packages with limited optical visibility.
**What Is X-ray inspection of solder?**
- **Definition**: Uses X-ray attenuation contrast to reveal joint shape, voids, bridges, and opens.
- **Coverage**: Provides visibility for hidden joints under array and leadless package bodies.
- **Modes**: Includes 2D X-ray and computed tomography for higher-detail analysis.
- **Limitations**: Image interpretation can be sensitive to overlap, resolution, and setup parameters.
**Why X-ray inspection of solder Matters**
- **Hidden-Joint Control**: Essential for defect detection where AOI cannot see solder interfaces.
- **Reliability Link**: Void and joint-geometry analysis helps predict thermal and mechanical risk.
- **Process Optimization**: X-ray trends directly inform paste and reflow tuning.
- **Failure Analysis**: Supports rapid diagnosis of field-return and production-yield anomalies.
- **Cost Efficiency**: Early detection reduces expensive downstream debug and rework.
**How It Is Used in Practice**
- **Program Setup**: Define package-specific algorithms and threshold criteria for automated analysis.
- **Sampling Strategy**: Balance inline throughput with risk-based sampling for critical packages.
- **Correlation**: Validate X-ray findings against cross-section and electrical test outcomes.
X-ray inspection of solder is **a primary inspection technology for hidden-solder-joint quality assurance** - x-ray inspection of solder should be integrated with process feedback loops to maximize yield and reliability impact.