IGBT and silicon carbide power modules are widely used in electric vehicles, renewable energy equipment, industrial drives, charging systems and high-power electronic applications. Their internal structures may include semiconductor dies, solder or sintered layers, ceramic substrates, bond wires, terminals and metal baseplates.
Many of these structures are sealed inside the module and cannot be examined through visual inspection. An electronics 3D X-ray system allows quality engineers to inspect internal features without cutting or damaging the component. Compared with a conventional two-dimensional projection, 3D CT can separate overlapping structures and reveal the location, shape and distribution of hidden abnormalities.
For power-module manufacturers, the purpose of using an industrial 3D CT scanner is not simply to obtain a clearer image. The inspection system must provide information that helps engineers evaluate production quality, investigate failures and improve manufacturing processes.
Power modules contain several materials with different densities, thicknesses and thermal properties. When a standard 2D X-ray image is captured, all structures along the X-ray path are compressed into one projection.
A solder layer may overlap with a semiconductor die, ceramic substrate, copper layer or metal baseplate. Although the image may show an abnormal region, inspectors may not be able to determine its exact depth or identify which internal layer contains the defect.
An industrial microfocus X-ray 3D/CT machine captures projections from multiple angles and reconstructs the internal structure. This enables inspectors to review cross-sectional slices, separate different depth levels and evaluate complex features that cannot be reliably interpreted from one 2D image. NIST identifies X-ray CT as an important nondestructive method for characterizing hidden defect morphology, dimensions and locations inside complex parts.
Voids are among the most important abnormalities evaluated in IGBT and SiC power modules. They may form in soldered or sintered layers because of trapped gas, contamination, material conditions or unsuitable process parameters.
Large or unevenly distributed voids can reduce the effective bonding area between the semiconductor die and substrate. They may also influence heat-transfer consistency and create local areas of increased thermal stress.
A 2D industrial Xray scanner can reveal the projected void area, making it useful for routine screening. However, the image may not show whether a void is located near the die, within the middle of the bonding layer or close to the substrate interface.
An industrial 3D CT scanner can reconstruct the bonding layer and provide more complete information about:
Void volume
Void depth
Void distribution
Distance from critical interfaces
Connection between several small voids
Relationship between the void and die edges
This information helps engineers compare process conditions and determine whether defects are isolated or part of a repeated manufacturing pattern.
Power modules may use fine bond wires or other internal interconnection structures to connect semiconductor dies with terminals. These connections can experience deformation, displacement, incomplete bonding or breakage.
In a standard X-ray projection, several wires may overlap. Dense terminals and metal structures may also obscure part of the wire path.
An electronics 3D X-ray inspection process can separate these features spatially and allow engineers to observe the internal connection from different directions. This is particularly useful when a failure cannot be explained through electrical testing alone.
Inspectors can evaluate:
Broken or displaced bond wires
Unusual wire-loop geometry
Incomplete connection areas
Internal terminal alignment
Foreign material near critical connections
Package deformation affecting internal structures
NIST is actively researching X-ray CT methods for three-dimensional semiconductor characterization and defect detection, reflecting the growing need to inspect complex subsurface features without destructive preparation.
IGBT and SiC modules may contain ceramic substrates combined with copper and bonding layers. Cracks, delamination or internal separation can be difficult to detect when dense structures overlap.
An industrial Xray scanner may reveal an abnormal line or density change, but a two-dimensional image does not always confirm which layer is affected. CT reconstruction allows engineers to review the module layer by layer and examine the suspected region through virtual cross-sections.
A suitable semiconductor inspection system can support the analysis of:
Ceramic substrate cracks
Layer separation
Internal porosity
Die-attach abnormalities
Sintered-layer inconsistencies
Terminal-position deviations
Hidden structural contamination
The inspection recipe must still be developed for the specific product. Module dimensions, material density, defect size and required resolution all influence the selected voltage, power, magnification and scanning method.
High-quality CT images do not automatically create a reliable inspection process. Manufacturers should define how samples are positioned, scanned, reconstructed and classified.
A practical inspection recipe should record:
Module type and dimensions
Target internal structure
Defects that must be detected
Required defect resolution
X-ray voltage and power
Geometric magnification
Number of projections
Reconstruction settings
Measurement method
Acceptance and review limits
The same settings should be used when comparing production batches. If operators frequently change contrast, filtering or reconstruction parameters, inspection results may become inconsistent.
The XCT8500 universal industrial X-ray inspection system combines an X-ray source, detector, scanning system, reconstruction system and analysis software. SEAMARK states that it supports 2D, 3D and CT inspection for nondestructive analysis, quality inspection and three-dimensional measurement.
Not every power module requires a complete CT scan. A conventional offline X-ray inspection machine may be sufficient for routine void screening, general alignment checks and rapid production sampling.
An industrial 3D CT scanner becomes more valuable when:
Several internal layers overlap
The defect depth affects the decision
Void volume must be measured
A crack or separation cannot be confirmed in 2D
Bond wires overlap in the projection
Detailed failure analysis is required
Engineers need virtual cross-sectional views
A practical factory workflow may use 2D X-ray for fast screening and apply CT to selected samples, failed components, new-product validation and complex engineering investigations. This approach balances inspection time with the need for detailed internal information.
Manufacturers should not select a semiconductor inspection system based only on maximum magnification. The equipment must match the module size, material density, target defect and production objective.
Important evaluation factors include:
X-ray source type
Detector resolution
Available sample space
Geometric magnification
CT scanning modes
Reconstruction speed
Measurement software
Defect-analysis functions
Recipe repeatability
Technical support
A demonstration should use representative IGBT or SiC samples rather than simple test objects. The supplier should show whether the system can identify the actual defects that influence the manufacturer’s quality decisions.
IGBT and SiC power modules contain overlapping semiconductor dies, bonding layers, ceramic substrates, wires and metal structures that cannot be fully evaluated through visual inspection.
A 2D industrial Xray scanner remains effective for fast screening and projected void analysis. However, an electronics 3D X-ray solution provides additional value when defect depth, volume and internal location must be understood.
By combining routine 2D screening with targeted 3D CT analysis, manufacturers can investigate hidden defects, validate new processes and improve power-module quality without destroying valuable samples.
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