What is Laminography?
Laminography is a 2.5D X-ray inspection method developed specifically for flat, extended components whose in-plane dimensions (x/y) are significantly larger than their depth (z). Classic applications are printed circuit boards (PCBs), solar modules and weld seams on sheet metal. Unlike standard CT, laminography rotates at an oblique angle relative to the board, so the component does not need to be fully irradiated.
Scientific background
In laminography, X-ray radiation is directed through the object at an oblique angle (typically 15–45°) while source and detector rotate jointly around an axis perpendicular to the component plane. From the projections obtained, a partial volume is reconstructed that resolves individual layers with high sharpness. Unwanted information from adjacent layers creates only blurred overlays rather than structured artifacts.
Relevant key metrics
- Lateral resolution is comparable to standard CT; axial resolution (z) is limited by the method.
- Typical resolutions: 5–50 µm lateral for micro-laminography.
- Relevant defects: voids, cold solder joints, delamination, hairline cracks in solder connections.
Standards and thresholds
- Standards: IPC-7711/7721 (PCB repair and rework standards), IEC 61188-7 (circuit carriers), ASTM E2445 (standard practice for laminography).
- Typical thresholds: Smallest detectable defect ≥ 2–3 voxels; for solder-joint CT a void detection requirement of < 25 % of the solder joint area is typical.
- Validity: Layer selectivity depends strongly on tilt angle and component thickness; method selection should be based on the number and thickness of layers.
Application in industrial practice
- Reliability inspection of BGA, QFN and through-hole solder connections.
- Detection of delamination and hairline cracks in multi-layer PCBs.
- Inspection of solar module interconnections and thin-film components.
Sources and reference date
- IEC 61188-7.
- ASTM E2445.
- IPC-7711/7721.
- Reference date: March 2026.