How to test IGBT with SAT(scanning acoustic tomography)
How to test IGBT with SAT(scanning acoustic tomography)
Blog Article
Introduction
What is scanning acoustic microscope?
A Scanning Acoustic Microscope (SAM) is a nondestructive testing technology that employs highfrequency sound waves to inspect the internal structure and defects of materials. It is especially suitable for quality control and failure analysis of electronic components such as semiconductor devices, packaged modules, and printed circuit boards.
What is IGBT?
Insulated Gate Bipolar Transistors (IGBTs) are indispensable components in modern power electronics systems, widely used in inverters, motor drives, and other power conversion devices. To ensure the reliability of these critical components, manufacturers and users must employ advanced inspection methods to identify potential issues. The Scanning Acoustic Microscope (SAM), as a nondestructive testing tool, provides highresolution images that aid engineers in gaining deep insights into the internal structure and health status of IGBTs.
Working Principle of SAM
SAM operates by emitting highfrequency ultrasound into the material and capturing the reflected echoes. These echoes are generated when the ultrasound encounters boundaries between different materials within the sample. By analyzing the amplitude and time delay of these reflections, SAM can create detailed images of the internal features, including voids, cracks, delaminations, and other structural anomalies. This capability makes SAM invaluable for assessing the integrity and reliability of complex devices like IGBTs.
Preparation for IGBT Inspection
To prepare an IGBT for inspection with SAM:
Cleaning: Clean the surface of the IGBT to remove any contaminants that could interfere with acoustic coupling.
Frequency Selection: Choose an appropriate ultrasonic frequency that balances penetration depth and resolution based on the size and material properties of the IGBT.
Couplant Application: Apply a couplant (such as water or oil) to facilitate effective transmission of sound waves from the probe to the IGBT.
Inspection Procedure
Instrument Setup: Configure the SAM settings according to the specific requirements of the IGBT, adjusting parameters such as frequency, gain, and focus.
Sample Positioning: Securely place the IGBT on the scanning stage and ensure it is properly aligned with the acoustic beam.
Scanning: Perform a Cscan or Bscan depending on whether you need a topdown view or crosssectional view of the IGBT.
Data Acquisition and Analysis: Collect the acoustic data and generate images that reveal internal structures and potential defects. Analyze these images to identify areas of concern.
Reporting: Document findings in a detailed report, highlighting detected flaws and suggesting corrective actions if necessary.
Applications and Benefits
SAM has been successfully applied to detect various issues in IGBTs, such as voids in solder joints, delamination between layers, and microcracks caused by thermal cycling. Early detection of these defects through SAM can prevent field failures and improve product reliability.
Conclusion
The use of Scanning Acoustic Microscopy for inspecting IGBTs provides a powerful means of ensuring component integrity and performance. By visualizing internal structures without causing damage, SAM supports both quality assurance during manufacturing and root cause analysis for failed units. As the demand for reliable power electronics continues to grow, SAM will remain a critical tool for maintaining high standards in IGBT production and maintenance.