Application Note XCT2601
About the sample: Multilayer ceramic inductor
Multilayer ceramic inductors contain conductive layers arranged within a ceramic body to form a three-dimensional coil. Key structural characteristics include the continuity of the conductive path, the thickness and uniformity of individual conductor layers, the spacing between adjacent turns, and internal defects such as pores or discontinuities. These features provide useful indicators of manufacturing consistency and the integrity of the internal conductive structure.
Because the conductive coil is embedded within the ceramic body, conventional cross-sectional inspection provides information from only a limited section of the component. Small internal pores and local variations in the conductive layers may therefore be difficult to evaluate comprehensively using destructive sectioning alone. X-ray CT provides a non-destructive method for examining the internal coil throughout a three-dimensional volume.
In this example, high-resolution X-ray CT was used to visualize the conductive structure of a 0402-size multilayer ceramic inductor, evaluate local variations in conductor thickness, and characterize pores ranging from the submicron to micron scale within the conductor.
Analysis procedure
- An 0402-size multilayer ceramic inductor was scanned using the CT Lab HR160.
- The internal conductive structure was visualized in 2D and 3D CT images.
- The conductive coil was segmented and analyzed to visualize local variations in conductor thickness.
- Small pores within a selected region of the conductor were segmented and analyzed by size.
1. CT scan
The CT image reveals the conductive layers embedded within the ceramic body. Individual conductive layers are distinguishable throughout the component, allowing regions of interest to be examined non-destructively.
Figure 1: CT cross-section showing the conductive layers within the inductor
2. Conductor thickness analysis
The conductive coil was segmented and analyzed in three dimensions to map thickness variations throughout the entire conductive path. The calculated thickness was color-coded from 1.35 to 15.19 µm, making it easy to identify locally thinner and thicker regions across the coil.
Figure 2: 3D thickness map of the segmented conductive coil
3. Pore size analysis
Closer inspection of the conductive material revealed small internal pores. We segmented these features from the surrounding conductor to visualize their distribution and support quantitative evaluation of pore size and porosity within the selected volume.
The detected pores were less than 2 µm, with some extending into the hundreds-of-nanometers range. The segmented 3D volume can also be used to calculate pore volume fraction when porosity is an important evaluation parameter.
Figure 3: Segmented pores within the conductive structure and pore-size analysis
Because the analysis is performed in three dimensions, pore size distribution and volume fraction can be evaluated throughout the analyzed volume rather than only in a single polished cross-section.
Video: Segmentation and quantitative analysis of conductor thickness and pore size
Conclusions
High-resolution X-ray CT enabled non-destructive visualization and quantitative analysis of the internal conductive structure of a multilayer ceramic inductor. Local variations in conductor thickness were mapped in three dimensions, and pores smaller than 2 µm were identified within the conductive material.
These results demonstrate how the CT Lab HR160 can characterize micron- and submicron-scale structures in multilayer electronic components, including conductor geometry and small internal pores that conventional cross-sectional methods struggle to evaluate.
