When electronic components fail—whether in the lab, in the field, or during production—accurately identifying the root cause is critical to improving reliability, preventing future issues, and meeting quality goals. Traditionally, electrical testing and physical inspection have been the go-to methods for failure analysis. But today, more and more engineers are turning to Scanning Acoustic Microscopy (SAM) as the preferred first step in the failure analysis workflow.
At CSAM Lab, we specialize in SAM and Confocal SAM (C-SAM™) imaging, and we’ve seen firsthand how this non-destructive technique provides critical insights faster, safer, and often more cost-effectively than traditional methods.
What Is SAM?
Scanning Acoustic Microscopy (SAM) uses high-frequency ultrasound to detect internal features within electronic components. It works by transmitting acoustic waves through a sample and analyzing the echoes that bounce back from internal material boundaries. Differences in acoustic impedance between materials make defects like delaminations, cracks, and voids clearly visible—without having to cut open the device.
Key Benefits of SAM Over Traditional Failure Analysis Techniques
1. Non-Destructive Insight
Unlike cross-sectioning or chemical decapsulation, SAM does not damage the part under test. This makes it ideal for:
- Preserving evidence before deeper destructive testing
- Screening expensive or limited-quantity parts
- Retesting or reusing the device after analysis
Example: A BGA package shows signs of thermal failure. Rather than delidding the package immediately, SAM imaging reveals delamination between the die and substrate, allowing targeted further analysis.
2. Faster Root Cause Isolation
Electrical tests may indicate that a part is failing, but they rarely explain why. SAM can quickly localize physical anomalies, allowing engineers to zero in on the problem area before committing to more invasive steps.
Example: A short circuit is detected in a QFN device. Instead of blindly delayering the entire die, SAM pinpoints a package crack from mechanical stress—cutting investigation time in half.
3. Layer-Specific and Subsurface Imaging
Unlike optical inspection, SAM can “see” inside components and distinguish between layers, making it highly effective for identifying:
- Internal voids in underfill or mold compound
- Cracks in die attach or leadframe interfaces
- Delamination between encapsulant layers
Electrical testing cannot provide any visual confirmation of these subsurface issues.
4. Ideal for Moisture-Sensitive Failures
Many field failures are caused by trapped moisture in plastic packages that expands during solder reflow—leading to “popcorn cracking.” SAM is one of the only techniques that can non-destructively confirm moisture-induced delamination.
5. Efficient Screening Tool
SAM is ideal for high-volume screening to catch early-life package defects or manufacturing process issues.
Example: A customer is seeing a 1% fallout rate on a new IC product. Using SAM to inspect 100 units helps uncover a recurring delamination pattern—before those units reach the field.
When to Use SAM in Your Workflow
SAM is most effective early in the failure analysis process, especially when:
- The defect is suspected to be structural or package-related
- The device must be preserved for further testing
- You need fast, actionable insights to guide next steps like cross-sectioning or decap
Final Thoughts: Don’t Start Blind
While electrical and physical failure analysis are still essential parts of the toolkit, SAM offers a unique combination of speed, precision, and non-destructive imaging that makes it the ideal first step. It helps you avoid unnecessary destructive testing, protect expensive samples, and get to the root cause faster.
At CSAM Lab, we specialize exclusively in SAM, C-SAM™, and precision cross-sectioning services. Our team delivers industry-leading acoustic imaging for failure analysis, quality control, and process validation.