Scanning Acoustic Microscope (SAM) and X-ray testing are two widely used non-destructive testing technologies, with obvious differences in working principles and applications.

1. Different Imaging Principles

SAM: Uses high-frequency ultrasonic waves (10MHz–300MHz) to form images through reflection and refraction inside materials, ideal for detecting interfacial defects such as delaminations and microcracks.

X-ray: Relies on electromagnetic waves penetrating materials and forms images based on density differences, more suitable for inspecting metal structures such as solder joints and wires, as well as high-density defects.

2. Difference in Detection Capability

SAM: Highly sensitive to internal delaminations and microcracks (resolution up to 0.05 μm), but less effective for metal solder joint inspection.

X-ray: Clearly identifies solder joint defects such as bridging and cold solder joints, but performs poorly on delaminations or microcracks with similar density.

3. Application Scenarios

SAM: Mainly used for semiconductor packaging (chip defects), composite materials (carbon fiber delamination), and biological sample testing.

X-ray: Suitable for electronic assembly (PCB solder joints), metal components (welds and porosity), and lithium battery inspection.

4. Safety and Limitations

SAM: Radiation-free; requires liquid coupling medium, not applicable to porous materials.

X-ray: Radiation protection is mandatory; strong penetration, but limited imaging performance for high-density stacked structures.

The two technologies are often used complementarily: X-ray screens macroscopic defects, while SAM performs precise inspection of microscopic delaminations.

Typical Application Cases of SAM and X-ray Testing

1. Application Examples of SAM

Semiconductor Packaging Delamination Detection

TO/SOT packaged chips: Detect delamination and debonding between lead frames and plastic encapsulation, and locate micron-level cracks (e.g., 0.1 μm interfacial separation).

BGA packaging: Identify voids or delaminations in underfill beneath solder balls to prevent chip failure caused by thermal stress.

Composite Material Defect Analysis

Detect micro-delaminations at bonding interfaces of carbon fiber reinforced polymer composites (aerospace components).

Locate microcracks inside diamond heat sinks to ensure heat dissipation reliability of high-power devices.

Biomedical Non-destructive Imaging

Scan internal structures of soft tissues and biological samples by water immersion coupling, avoiding damage from ionizing radiation.

2. Application Examples of X-ray Testing

Electronic Assembly Solder Quality Inspection

BGA/CSP solder joints: Detect bridging, cold solder and voids on mobile phone motherboard solder joints caused by uneven solder distribution.

QFN packaging: Insufficient or offset solder under pins to prevent poor electrical contact.

New Energy Battery Quality Inspection

Analyze electrode stacking alignment of power batteries via 2D/3D imaging; identify anode/cathode layer offset which may cause short-circuit risk beyond threshold.

Inspect the integrity of tab welding of lithium batteries to avoid thermal runaway hazards.

Metal Component Non-destructive Testing

Screen porosity in welds of automotive engine blocks by density difference imaging.

Locate inclusions and shrinkage cavities inside castings such as aluminum alloy wheels.

3. Typical Complementary Application Cases

Combined Inspection of Chip Packaging

X-ray for rapid screening of macroscopic solder defects such as BGA solder bridging;

SAM for precise detection of microscopic delaminations such as debonding between chip encapsulation and substrate interface.

Failure Analysis of High-end PCB

X-ray detects gold wire breakage;

SAM locates delamination between substrate copper layer and PP resin.

Note: SAM is sensitive to air gaps such as delaminations and cracks; X-ray excels at density-based imaging for metal solder joints and foreign inclusions. Combined use of the two technologies covers over 90% of industrial non-destructive testing requirements.