Need for speed: Boosting X-ray inspection speed in advanced electronics

Need for Speed: Boosting X-ray Inspection Speed in Advanced Electronics

October 28, 2026

As electronics become more powerful and advanced packaging technologies more complex, manufacturers face the challenge of detecting ever-smaller defects without reducing throughput. Optical inspection methods cannot reveal the buried structures found in high-power electronics, chiplets, HBM, through glass vias (TGVs), and advanced 3D packages. X-ray inspection and automated X-ray inspection (AXI) provide the required visibility, but higher resolution and penetration have traditionally come at the expense of speed. Recent advances in micro and nano focus X-ray source technology are overcoming this trade-off by delivering higher photon flux, improved contrast-to-noise ratio, and faster imaging. In this post we review these developments in high-power electronics, where higher voltage and power are required to penetrate through dense structures while maintaining micro-scale imaging, and advanced packaging where increasing complexity from vertical integration and sub-micron resolution combine. We highlight how increased throughput can be achieved while maintaining reliable defect detection.

Methodology

Inspection throughput depends on the entire imaging chain, including the X-ray source, detector, sample geometry, system stability, magnification, and image-processing software. To isolate the influence of the X-ray source, this study compares different source technologies while keeping the remaining inspection parameters constant. Commercial electronics samples and standardized test structures were examined using both microfocus and nanofocus X-ray sources supplied by Comet X-ray. High-power electronics were evaluated using 2D imaging at voltages between 90 and 160 kV to assess how higher source voltage affects penetration, contrast, and inspection speed. For advanced packaging applications, high-resolution measurements were performed across a similar voltage range using nanofocus sources and high magnification.

Results and Discussion

High-power electronics

A sealed-type microfocus source was used to evaluate the effect of higher voltage operation on dense electronic assemblies, including an IGBT module used in electric vehicle traction inverters. Images are shown in the figure above. At 90 kV, the cooling pin fins could not be penetrated sufficiently, making void detection impossible, whereas at 130 kV and 160 kV, voids became visible with significantly higher contrast at the higher voltage. The contrast values are summarized in the table below. This increase in contrast translates directly into an exposure time reductions while maintaining defect detectability, resulting in substantially higher inspection throughput. While even higher voltages could further improve penetration, they would also increase shielding requirements, source weight, integration complexity, and overall system cost. These results show that higher source voltage can significantly improve both image quality and throughput, particularly for thick samples in at-line and in-line inspection environments.

Inspection location	90 kV	130 kV	160 kV
Large void center	0%	22%	33%
Small void center	0%	10%	25%

Advanced packaging

Advanced packaging requires the inspection of extremely small features, with defects often measuring as little as 0.5 µm. An example is a GPU with high-bandwidth memory (HBM) stacks connected by TSVs on top of C2 and C4 bump layers (see image below). In the image, voids in the 100 µm C4 bumps and the 20 µm HBM bumps can clearly be identified. Conventional nano-focus sources provide sufficient resolution but are limited by low dose rates, resulting in long scan times, especially for 3D inspections. The Fyne NF4 delivers up to four times more usable X-ray dose at 400nm resolution, while the NF12 achieves up to ten times higher dose at 1.1 µm resolution, significantly improving throughput. Selecting a resolution that matches the actual defect size is therefore essential for efficient inspection.

Lifetime contribution to inspection speed

Maintenance is a key factor in inspection throughput, as service interruptions reduce system availability. In open nano-focus sources, emitter lifetime often limits operation because filaments must be replaced after only a few hundred hours. By contrast, the Fyne nano source showed no significant loss of resolution after more than 2,600 hours of continuous operation, equivalent to around 11 months at 8 hours per day. This greatly reduces maintenance requirements, downtime, and operator intervention. The target can also be operated at a single position for at least twice the emitter lifetime, eliminating readjustments during normal maintenance intervals. For sealed sources, lifetime and reliability are equally important for inspection efficiency. The improved thermal robustness of metal-ceramic tubes reduces tube failures and extends operational lifetime.

Commercial implications: cycle time, uptime, and cost

The technical advantages of an X-ray source only create commercial value if they improve inspection speed or confidence without affecting takt time. In high-power electronics, higher voltage and power can reduce false negatives in metal-shaded areas and shorten inspection times. For advanced packaging, increased dose at sub-micron resolution helps minimize the scan-time penalty of high-resolution 3D inspection. Inspection economics depend not only on image quality but also on acquisition time, machine availability, and maintenance requirements. Higher dose rates can significantly reduce 3D scan times, while longer maintenance intervals improve system uptime. Conversely, excessive voltage or unnecessarily high resolution can increase shielding requirements, inspection time, and overall costs. The most effective solution is therefore application-specific and must balance technical performance with economic efficiency.

Conclusion

Electronics are becoming more complex, making defect detection more challenging
X-ray inspection reveals hidden defects that optical methods cannot detect
Nano focus X-ray sources can improve image quality and inspection speed
Higher voltages can reduce inspection time while maintaining detectability
Optimized X-ray systems increase throughput, yield, and uptime

Chris Nicholson

Chris Nicholson is Product Manager for microfocus and nanofocus X-ray sources at Comet X-ray. His responsibilities include the development and strategic management of X-ray source technologies used in electronics manufacturing, semiconductor inspection, and battery applications.

Before joining Comet X-ray in 2023, Christopher Nicholson worked in both academic research and industrial instrumentation. He completed a PhD in physics at the Max Planck Institute and Freie Universität Berlin, where his research focused on laser-induced phase transitions at metal-semiconductor interfaces. Today, his work focuses on advancing X-ray source technology for high-resolution inspection and supporting customers in addressing emerging challenges in electronics and semiconductor manufacturing.

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