X-Ray (RTG) PCB inspection — quality control where AOI cannot reach
RTG PCB inspection, also known as X-Ray inspection, is a method of quality control for solder joints invisible to the naked eye and to AOI inspection. Key for BGA, QFN components and THT connectors with hidden connections. Our RTG scanner lets you detect potential errors and problems before your product reaches final assembly.
Request a quote →What is X-Ray (RTG) inspection and when is it essential?
AOI (Automatic Optical Inspection) controls what is visible — the board surface after the soldering process. However, the growing popularity of BGA (Ball Grid Array), QFN (Quad Flat No-lead) and other components with hidden leads means that a growing part of solder joints is invisible after assembly.
RTG inspection sends an X-ray beam through the board and creates an image of the internal structure of the joints. RTG PCB analysis can detect:
- Missing solder balls under BGA
- Solder bridges between pads invisible from the outside
- Voids and bubbles inside joints — especially important in power and medical electronics
- Cold joints and incomplete solder paste melting
- Component alignment errors hidden under the housing
When to use X-Ray inspection?
BGA and flip-chip components
Processors and microcontrollers, FPGA chips, memory modules, communication chips in BGA packages — solder balls are completely hidden under the housing. The only way to verify joint quality is X-Ray.
QFN and LGA components
Power, RF and mixed-signal circuits in packages without visible side leads. AOI will not detect problems with thermal pads underneath.
Medical and industrial electronics
Projects where the consequences of a hidden joint defect are critical — medical devices, control systems, safety electronics.
Process verification when launching a new project
X-Ray at the first series confirms the quality of the soldering process and line settings before series production starts.
X-Ray (RTG) inspection at Siltegro — what is worth knowing?
New X-Ray machine
Siltegro has an RTG PCB inspection machine — operated by a team working as per IPC-A-610, which guarantees a reliable assessment of joint quality, not just an image.
Integration with the AOI process
X-Ray inspection complements AOI inspection — together they form a complete quality control system: AOI detects visible defects, X-Ray detects hidden ones.
Inspection report
RTG analysis results are documented and attached to the order report. You gain full traceability, and we store X-Ray analysis results for you.
Qualified interpretation of results
We carry out RTG analysis as per the IPC-A-610 standard — the inspection result is not just an X-ray image, but an assessment of the joint's compliance with quality acceptance criteria and a professional comment.
Technical parameters
| Method | RTG / X-ray radiographic inspection |
| Components | BGA, QFN, LGA, THT, flip-chip |
| Detected defects | Missing balls, bridges, voids, cold joints, alignment errors |
| Result interpretation | Per the IPC-A-610 standard |
| Report | Yes — attached to the order documentation |
| Contact time | 24 hours |