Scanning Acoustic Microscope for Non-Destructive Failure Analysis and Material Characterization/ Quality Control

January 15,2023

Scanning Acoustic Microscopes (SAM), also called Acoustic Micro Imaging Equipment (AMI), use ultrasound pulses (>20kHz) to inspect and characterize the internal structures of microelectronics such as semiconductors, circuit boards, ceramic capacitators, LED packages, as well as biological and medical samples.

A typical SAM consists of an ultrasonic pulser-receiver, a mechanical scanner, and an image processor.

Scanning Acoustic Microscope Structure diagram
Figure 1: Scanning Acoustic Microscope Structure (Yu, 2020) https://appmicro.springeropen.com/articles/10.1186/s42649-020-00045-4

How do Scanning Acoustic Microscopes work?

  1. Piezoelectric transducers, which convert electrical energy into mechanical vibrations, produce ultrasonic waves.
  2. The ultrasonic waves are focused through a lens system, before traveling through the material under inspection.
  3. Internal features of the inspected material, such as boundaries between different materials, variations in density, and other subsurface structures interact with the ultrasound waves.
  4. The ultrasound waves are then reflected to the piezoelectric transducer, a part of which also functions as a receiver.
  5. The mechanical scanner moves the focused ultrasound beam and allows for systematic scanning.
  6. The received signals are then processed to create an image of the internal structure of the material. Variations in the time of flight (TOF) and intensity of the reflected ultrasound waves are used to generate an image which reveals the existence of any subsurface defects, interfaces, or other variations in material properties.
Figure 2: Scanning Acoustic Microscope C-Scan System (Hozumi, et al., 2013)
Scanning Acoustic Microscope C-scan system

How do you choose a suitable SAM？

 

Thanks to its high-resolution and sensitivity to sub-surface features, SAMs are ideal for non-destructive testing of subsurface defects such as voids, delamination, and cracks. They are often used for quality control, failure analysis and research in microelectronics, material sciences, and biological imaging.

 

Due to the wide range of potential applications, SAMs can be configured in various ways. Some common customizations include:

Frequency range:

  • The frequency of the ultrasound waves dictate the penetration depth and resolution of SAM imaging. Generally, higher frequency waves produce higher resolution images, because they have shorter wavelengths that allow them to detect smaller features in the specimen.

Penetration Depth:

  • There is a trade-off between frequency and penetration depth, where higher frequency translates to lower penetration depth. Therefore, the optimal choice will depend on each user’s specific inspection requirements.

Scan modes:

  • Multiple scanning modes exist. Choosing the optimal one will depend on the specimen shape, material, inspection needs, and other factors.
  • Common types of scanning modes include A-scan (a raw waveform), B-scan (cross-sectional scan along a selected plane), and C-scan (contour scan providing a top-down view of the inspected area).

Sample stage:

  • Boundary dimensions of the scanning stage determine the size and shape of samples that can be inspected.

Data processing software:

  • Customizable software options exist for image processing and data analysis.

Customizable Scanning Acoustic Microscopes on US Korea Hotlink

 

To meet various inspection requirements for the microelectronic, medical, automotive, aerospace, and advanced material industries, we offer standard and custom scanning acoustic microscopes (5-300 MHz) with detailed acoustic analysis capabilities.

 

Our SAM models are developed in partnership with Pukyoung National University‘s R&D laboratory, and are equipped with self-developed multi-channel, high bandwidth ultrasonic pulser-receivers that enable high-speed and high-resolution 2D and 3D imaging output. We incorporate CUDA GPUs to ensure high-speed image processing and fast defect detection.

 

Our models are equipped with advanced C-scan capability, which provides a detailed and comprehensive visual representation using colors or contour lines to represent variations in the underlying materials.

See our SAMs in action:

Scanning Acoustic Microscopy Testing Process for Semiconductor and Advanced Materials Components

Learn more about our scanning acoustic microscopes and project experience, or contact us to speak with a specialist.

Yu, H. Scanning acoustic microscopy for material evaluation. Appl. Microsc. 50, 25 (2020). https://doi.org/10.1186/s42649-020-00045-4

Hozumi, et al. (2013). Quantitative Acoustic Microscope- Measurement, Analysis, Biological and Material Science Applications [Lecture notes]. Retrieved from https://ewh.ieee.org/conf/uffc/2013/download/ius/maev1.pdf