Quality assurance in electronics relies on several key non-destructive and destructive inspection methods. Each technique offers unique benefits and limitations depending on the defect type, resolution needs, and production environment.
Main inspection methods include:
Scanning Acoustic Microscopy (SAM / C-SAM): Uses high-frequency sound waves to detect hidden voids, delaminations, and cracks inside components and solder joints. Ideal for non-destructive internal inspection.
X-ray Inspection (2D Digital Radiography & 3D CT): Provides high-resolution internal imaging through X-rays, revealing solder joint quality and component positioning. CT adds volumetric defect analysis for complex parts.
Automated Optical Inspection (AOI) & 3D AOI: Visually inspects surface defects, component misalignments, and solder joint fillets using cameras with 2D or 3D imaging. Fast for surface-level faults but limited in subsurface detection.
Infrared Thermography (Lock-in & Pulse): Detects subsurface defects by analysing thermal response to controlled heating. Effective for delamination and thermal path issues but less precise for small voids.
Electrical Testing (Flying Probe & ICT): Measures electrical connectivity and component functionality to identify shorts, opens, and parametric failures. Highly accurate but limited to electrical faults.
Destructive Methods (Cross-sectioning & Dye-and-Pry): Provide direct physical evidence of internal defects and material interfaces. Used for failure analysis and process validation but not suitable for inline production.
Together, these technologies form a comprehensive inspection strategy tailored to specific defect types and industry requirements. The focus now shifts to a detailed side-by-side comparison emphasising precision, speed, and cost efficiency across these methods.
When comparing scanning acoustic microscopy (SAM) with other inspection techniques, several key factors shape the decision-making process. Here’s a clear framework to evaluate them side-by-side:
| Criterion | What to Consider | Impact on Selection |
|---|---|---|
| Resolution & Defect Size Detection | Ability to detect tiny features like solder voids or cracks | Higher resolution means better defect detection at micro-level |
| Penetration & Material Compatibility | How deep waves or signals can inspect different substrates | Determines suitability for multilayer PCBs, power modules, or thick cases |
| Inspection Speed & Throughput | Cycle time per unit and volume handled hourly | Faster inspection suits high-volume or inline testing environments |
| Automation & Industry 4.0 Integration | Support for AI, robotics, inline systems, and data analytics | Critical for smart factories and consistent quality control |
| False Positives & Negatives | Accuracy in defect calls without unnecessary alarms or misses | Low false rates improve yield and reduce rework costs |
| Cost Factors (CAPEX/OPEX) | Initial investment vs. operating and maintenance expenses | Balancing upfront costs with long-term savings influences ROI |
| Radiation Safety & Regulations | Exposure risks and compliance needs especially for X-ray methods | Safety protocols affect lab setup and operational flexibility |
Each inspection method—whether SAM, X-ray, optical, or infrared—scores differently against these aspects. For example, SAM offers excellent resolution and non-destructive delamination detection but may face challenges in rough surfaces or thick materials. X-rays penetrate complex assemblies well but require strict radiation safety controls. Understanding these factors helps tailor inspection setups to specific product needs and industry standards.
For detailed insights into the capabilities and limits of SAM and other techniques, check our technical resource on advanced inspection solutions. Also, industry-specific use cases highlight how automation and integration have evolved in smart electronics manufacturing.
SAM, or C-SAM (C-mode Scanning Acoustic Microscopy), uses high-frequency ultrasound waves to detect hidden defects like voids, delaminations, and cracks inside PCBs and semiconductor packages. It excels at identifying non-wet solder joints and die-attach delamination with resolutions down to a few microns, depending on the transducer frequency (usually 50–300 MHz). Its precision is unmatched for internal interface inspection, making it a top choice in automotive and power module applications.
However, SAM has some limits: air gaps, rough surfaces, and very thick substrates can reduce signal quality. Cycle times vary but typically range from seconds to a few minutes per scan area, slower than some inline optical methods. The cost tends to be higher in CAPEX and requires skilled operators, but advances like AI-driven image analysis and inline SAM integration (read about inline SAM inspection speed) are improving throughput and ease of use.
X-ray inspection uses ionizing radiation to image internal structures, ideal for identifying solder joint voids, bridging, and component misalignment. Digital radiography offers quick 2D snapshots with decent resolution for many defects, while computed tomography (CT) provides detailed 3D views for complex assemblies.
Strengths include good penetration through metals and dense materials and fast inspection speeds, especially for single-plane 2D X-rays. Limitations come from lower sensitivity to delamination versus SAM, radiation safety concerns, and higher equipment and operation costs for CT. Throughput varies but can be automated for inline use.
AOI systems scan boards with high-resolution cameras to detect surface defects like missing components, solder joint quality, and placement errors. 3D AOI adds height data, improving detection of solder volume and certain defects invisible to 2D optical methods.
AOI shines in speed and cost efficiency for high-volume PCB assembly but cannot see inside components or under solder joints. Resolution depends on camera optics but generally cannot match SAM or X-ray for internal defects. AOI is widely used in SMT lines for fast pass/fail sorting.
Infrared thermography methods apply heat pulses or modulated heat (lock-in) to a component, observing thermal patterns to reveal subsurface defects like delamination or cracks. It is non-contact and can cover large areas quickly.
While efficient for detecting certain defect types, thermography is limited by depth penetration and material emissivity differences, and it requires specialized expertise to interpret results properly. Cycle times are generally fast, but expenses can vary depending on the system complexity.
Electrical tests check continuity, shorts, and component functionality, using flying probes or in-circuit testers (ICT). These methods are highly accurate for functional defects and open/short circuits but can’t image physical defects inside components or solder joints.
Flying probes offer flexible, low-volume testing with longer cycle times, while ICT is faster but suited to large production runs. Both have moderate costs and are standard in many production lines.
These destructive tests physically slice or pry components apart to directly observe internal features under a microscope. They are highly precise for confirming defect types but very slow, expensive, and not suitable for inline production testing.
Used mainly for failure analysis or process validation, these methods provide ground truth data but lack throughput or practicality for routine inspection.
Here’s a clear snapshot comparing the main inspection technologies based on seven key criteria. The table shows both visual ratings (★ out of 5) and numeric scores where applicable, helping you quickly gauge how each method stacks up in precision and efficiency for 2025.
| Criteria | Scanning Acoustic Microscopy (SAM) | 2D/3D X-ray (DR & CT) | Automated Optical Inspection (AOI/3D AOI) | Infrared Thermography (IR) | Electrical Test (Flying Probe/ICT) | Cross-sectioning & Dye-and-Pry |
|---|---|---|---|---|---|---|
| Resolution & Defect Size | ★★★★☆ (1–10 µm) | ★★★☆☆ (10–50 µm) | ★★★☆☆ (50–100 µm) | ★★☆☆☆ (100+ µm) | ★★★★☆ (Down to µm-level electrical faults) | ★★★★★ (Sub-µm, destructive) |
| Penetration & Material Range | ★★★★★ (Thick, multi-layer materials) | ★★★★☆ (Good for metals & composites) | ★★☆☆☆ (Surface level only) | ★★★☆☆ (Surface & shallow layers) | ★★★☆☆ (Electrical pathways only) | ★★★★★ (Complete analysis) |
| Inspection Speed & Throughput | ★★★☆☆ (Moderate, depends on scan area) | ★★★★☆ (Fast for 2D, slower CT) | ★★★★★ (Very fast inline) | ★★★★☆ (Moderate to fast) | ★★★☆☆ (Slow for complex boards) | ★★☆☆☆ (Very slow, destructive) |
| Automation & Industry 4.0 Fit | ★★★☆☆ (Limited inline options) | ★★★★☆ (High automation available) | ★★★★★ (High inline automation) | ★★★☆☆ (Semi-automated) | ★★★☆☆ (Semi-automated) | ★☆☆☆☆ (Manual, destructive) |
| False Positives & Negatives | ★★★★☆ (Low false negatives on voids) | ★★★☆☆ (Moderate, overlaps possible) | ★★★☆☆ (Surface-only defects) | ★★☆☆☆ (High for subtle defects) | ★★★☆☆ (Misses non-electrical faults) | ★★★★★ (Ground truth standard) |
| Cost (CAPEX/OPEX) | ★★☆☆☆ (Mid to high upfront, low maintenance) | ★★★☆☆ (High upfront & OPEX) | ★★★★☆ (Lower upfront, moderate OPEX) | ★★★☆☆ (Moderate CAPEX & OPEX) | ★★★★☆ (Lower CAPEX, moderate OPEX) | ★☆☆☆☆ (High per-test cost) |
| Safety & Regulations | ★★★★★ (No radiation, safe) | ★★☆☆☆ (Radiation protection required) | ★★★★★ (Safe, optical) | ★★★★★ (Safe, non-ionizing) | ★★★★★ (Safe) | ★★★★★ (Safe, but destructive) |
This table highlights how SAM holds a strong position in penetration, defect detection precision, and safety, while automated optical inspection shines in speed and inline automation. The best choice depends on your specific defect types and inspection needs.
By the way, the AOI inspection equipment introduced by Jeenoce can detect the bonding process, so its precision is relatively high. If you have any higher configuration requirements, don't worry. Just fill out the form and get in touch directly with our engineering team.
For more on modern scanning acoustic microscopy capabilities and how it compares technically with X-ray systems, check out our detailed overview of scanning acoustic microscopy.
When it comes to choosing the best inspection method, the defect type greatly influences which technology wins out. Here’s a quick breakdown of the top performers in key defect categories:
Voids in Solder Joints: Scanning Acoustic Microscopy (SAM) leads for detecting fine voids, especially in BGAs and power modules. Its high resolution and ability to visualize internal layers without X-ray’s line-of-sight limitations make it ideal for spotting hidden solder voids.
Die-Attach Delamination: SAM again is the clear winner here. It excels in identifying non-destructive delamination issues within die attach layers, outperforming X-ray and thermography which struggle with subtle internal separations.
Cracks in MLCC or Substrate: X-ray CT provides the best overall view for substrate and MLCC cracks through its 3D imaging. SAM can detect some cracks but limited penetration depth and surface roughness can reduce effectiveness.
Non-Wet / Head-in-Pillow Defects: These subtle wetting issues are tricky, but SAM’s acoustic micro imaging gives superior discrimination compared to standard X-ray or AOI. It reveals voiding and poor solder connections missed by optical and electrical tests.
Component Placement Errors: Automated Optical Inspection (AOI), especially 3D AOI, remains unmatched for component misalignment and polarity errors. While SAM and X-ray focus on internal defects, AOI ensures surface assembly correctness swiftly.
This decision matrix shows that no single method covers all defects equally, but SAM stands out for internal voids and non-destructive delamination, critical for high-reliability electronics. For comprehensive inspection strategies, combining SAM with X-ray and AOI provides the best defect coverage and process stability.
Different industries and products require specific inspection strengths, and the best non-destructive testing method varies accordingly.
Automotive electronics demand high reliability and strict quality standards. Scanning Acoustic Microscopy (SAM) leads here, especially for detecting voids and die-attach delamination in power modules and advanced packaging. Its ability to catch hidden defects without damaging the part aligns perfectly with AEC-Q100/Q104 requirements. Inline SAM solutions ensure fast throughput with consistent results, reducing returns and failures.
5G components and System-in-Package (SiP) modules benefit most from high-resolution X-ray CT and advanced AOI techniques. Their tiny multi-layered structures make 3D X-ray inspection ideal for spotting cracks and non-wet joints. However, SAM complements X-ray by providing sensitive delamination detection unmatched by other methods. Hybrid inspection setups combining SAM and X-ray are increasingly common here, boosting defect coverage and process stability.
Medical implants require zero-compromise on safety and material compatibility. SAM stands out with its ability to detect internal delamination or voids in polymer-encapsulated devices non-destructively. Infrared thermography is less favored due to limited penetration, while X-rays can raise regulatory concerns related to radiation exposure. The non-invasive nature of SAM makes it a go-to for qualifying medical-grade electronics and ensuring compliance.
For high-volume consumer and industrial PCBA production, speed and cost-efficiency rule. Automated Optical Inspection (AOI) and 3D AOI dominate here with rapid cycle times and ease of integration on SMT lines. While SAM offers deeper defect detection, its cycle time and CAPEX may not suit all mass production lines. Still, for critical applications with higher quality demands, integrating inline acoustic microscopy boosts overall process control.
By matching inspection tech to industry needs, manufacturers can optimize both precision and efficiency.
In recent years, tier-1 automotive manufacturers have reported significant improvements in product quality and reliability thanks to inline scanning acoustic microscopy (SAM). Using SAM, these companies achieved notable return reductions by catching hidden defects like die-attach voids and delamination early in the production line. Inline SAM’s high resolution and ability to detect non-wet solder joints helped maintain strong process stability, which traditional X-ray inspection systems sometimes missed.
Another compelling case comes from power module manufacturers, where SAM identified 300 µm die-attach voids that were invisible to 2D and 3D X-ray inspections. These small voids can severely impact thermal performance and long-term reliability. Deploying C-SAM in their inspection routine enabled defect detection earlier, reducing costly failures in the field and improving overall throughput.
These cases highlight the advantage of acoustic micro imaging for BGA voids and die attach inspection techniques, especially when combined with automation for inline operation. For more detailed insights on integrating SAM into production lines, check out our resources on inline scanning acoustic microscope solutions and scanning acoustic microscopy resolution improvements.
Scanning Acoustic Microscopy (SAM) is powerful but not without limits. One common challenge is detecting defects near air gaps or on rough surfaces, where acoustic signal reflection can reduce image clarity. Thick substrates also pose a problem, as ultrasound penetration weakens, making it harder to spot deeper flaws.
Fortunately, advances in modern transducers—ranging from 50 MHz up to 300 MHz—are improving resolution and penetration balance. Higher frequencies sharpen detail but work best with thinner materials, while lower frequencies penetrate deeper with some resolution trade-offs. Combining different frequency ranges lets you optimize for varied inspection needs.
Another game-changer is AI-enhanced image analysis. Smart algorithms now reduce noise, improve defect recognition, and cut down false positives. This helps overcome some inherent acoustic microscopy limitations by sharpening defect visibility and boosting overall reliability.
For those interested in integration best practices and enhancing inline acoustic microscopy performance, explore our detailed guide on inline scanning acoustic microscope integration tips.
By pairing advanced hardware with AI-driven software, SAM can continue expanding its role as a top choice for high-precision, non-destructive inspection across industries.
The next few years will see big jumps in scanning acoustic microscopy technology. Expect 1 GHz+ transducers that push resolution and defect size detection to new limits. These ultra-high-frequency probes will reveal even finer microvoids and delaminations, critical for advanced semiconductor packaging and power modules.
Real-time inline SAM inspection will become more common, integrating directly into SMT production lines. This leap will boost throughput and allow immediate process feedback, reducing defects and rework. AI-driven image analysis and smarter automation will support these inline setups, making SAM a vital tool in Industry 4.0 environments.
Another promising trend is the rise of hybrid SAM + X-ray inspection stations, combining the strengths of both methods. While SAM excels at detecting delamination and voids inside complex multilayers, X-ray adds high-speed volumetric imaging for solder and component alignment. Together, they provide a more complete picture of hidden defects in PCBA and advanced modules.
These innovations will help manufacturers handle evolving challenges in automotive electronics, 5G RF modules, and medical implants with higher precision and efficiency. For a smooth transition to these advancements, it’s wise to consult the integration tips for SMT lines and prepare for evolving operational needs.
In , the 2026–2030 horizon for scanning acoustic microscopy looks set to deliver:
1 GHz+ probes for ultra-fine resolution
Real-time inline SAM for higher throughput and faster feedback
Hybrid SAM/X-ray stations for comprehensive defect detection
Stronger AI and automation support for Industry 4.0 integration
These trends will solidify SAM’s role as a leading NDT method in high-end electronics manufacturing.
When you’re ready to invest in a Scanning Acoustic Microscope (SAM), asking the right questions upfront can save time and money. Here are 12 critical vendor questions to guide your decision:
What frequency ranges do your SAM transducers cover?
Higher frequencies boost resolution but reduce penetration depth.
Can the system handle different materials and PCB thicknesses common in my products?
Material compatibility affects image quality and detection limits.
What is the typical inspection speed and throughput for inline and offline modes?
Speed impacts your production efficiency.
Does the system support automation and Industry 4.0 integration?
Compatibility with your SMT line’s data ecosystem is key.
How does the SAM handle difficult surfaces like rough or uneven areas?
Some transducers and software handle these better.
Can the software differentiate between false positives and real defects?
AI-enhanced analysis can drastically reduce inspection errors.
What is the maintenance schedule and associated costs?
Understand ongoing expenses beyond CAPEX.
Is training included for operators and engineers?
Smooth adoption depends on user knowledge.
What support and upgrades are offered?
Long-term vendor support matters for tech investments.
Can it integrate seamlessly into existing SMT lines?
Check compatibility with your line’s layout and flow.
How customizable is the system for specific defect types or product families?
Flexibility avoids retooling headaches later.
What safety and regulatory certifications does the system meet?
High safety standards provide peace of mind.
Jeenoce specializes in integrating SAM into SMT lines smoothly, focusing on minimal disruption and maximum data flow. Here are some practical tips:
Plan inline vs. offline use based on throughput needs. Inline SAM inspection boosts process control but requires careful placement.
Use data integration software to connect SAM results directly to your MES or SPC systems. This ensures fast defect feedback and trend analysis.
Train operators early on image interpretation and system basics. Better user knowledge shortens ramp-up time.
Combine SAM with complementary methods like X-ray or AOI in your line for more thorough coverage. Hybrid approaches catch more defect types.
For those interested in this specialized integration, Jeenoce’s solutions provide tailored automation and SMT line expertise to maximize SAM effectiveness and uptime. Learn more about Jeenoce’s SMT line integration services and how they can fit with your inspection goals.
This checklist and integration insight ensure you get the most from your scanning acoustic microscopy investment—boosting defect detection and process stability in your production line.
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