Test & Measurement
The power trio behind superior SAM performance
Selecting and integrating the right transducers, digitizers, and software drives superior scanning acoustic microscopy quality control
F
or manufacturers in electronics, aerospace, and advanced materials like metals, alloys, and composites, scanning acoustic microscopy (SAM) offers a powerful quality control tool, ensuring structural integrity, reliability, and performance – all without damaging a single component. SAM uses high-frequency ultrasound to inspect and characterize internal features of materials, detecting cracks, voids, inclusions, and delaminations that could compromise performance.
SAM is a powerful non-invasive and non-destructive method for inspecting internal structures in optically opaque materials. Depth-specific information can be extracted and applied to create two- and three-dimensional images without the need for time-consuming tomographic scan procedures and more costly X-rays. Today, SAM facilitates the detection of much smaller defects than previously possible. “Advanced, phased array SAM systems make it possible to move to a higher level of failure analysis because of the level of detection and precision involved. In the past, detecting a 500-micron defect was the goal; now it is a 50-micron defect. With this type of testing, we can inspect materials and discover flaws that were previously undetected,” said Hari Polu, president of OKOS, a US-based manufacturer of industrial SAM ultrasonic non-destructive testing systems. The company serves the electronics manufacturing, aerospace, and metal/alloy/ composite manufacturers, and end-user markets.
For electronics manufacturers, SAM is said to be indispensable for inspecting microchips, bonded wafers, and underfills, where failure is not an option. Aerospace firms rely on it to identify subsurface flaws in lightweight composites or high-performance alloys, ensuring safety in flight-critical applications. In metals and composites, it verifies adhesion quality and detects fatigue or internal corrosion early, saving money and lives.
38 October 2025
Scanning acoustic microscopy (SAM) serves as a critical non-destructive tool for evaluating internal structures in electronics, aerospace, and composite materials.
However, to unlock the full power of SAM, manufacturers need the right system. Toward this goal, the most effective SAM systems are built on a triumvirate of high- performance components: transducers, digitizers, and software.
Optimizing SAM with critical components
Polu explains how transducers, digitizers, and software seamlessly work together in scanning acoustic microscopy to benefit manufacturers.
“Transducers generate and receive the ultrasound signals, acting as the system’s ‘eyes.’ Digitizers convert high-frequency acoustic signals into precise digital data for analysis. Software brings it all together, enabling real-time visualization, defect identification, and actionable reporting. When these three elements work in harmony, SAM
Components in Electronics
becomes more than a quality control step – it becomes a competitive advantage,” says Polu.
Transducers
A scanning acoustic microscope operates by utilizing a transducer that converts electrical energy into highly focused, ultrahigh- frequency sound waves. These waves are directed to a precise point on the target object, enabling internal inspection with exceptional accuracy. The shape of the transducer’s lens and the frequency of the sound waves determine both the focal length and the resolution of the scan. As the sound waves interact with the internal features of the material, they reflect back to the transducer, which then converts the returning acoustic signals into voltage. This returning analogue signal is subsequently amplified by a pulser/receiver and digitized for further analysis. All ultrasonic scanning
systems rely on this essential dual function – signal generation and detection via at least one transducer – to perform precise, non- destructive evaluations of internal structures. Transducers come in a variety of sizes and shapes for different applications. Some require direct contact with a material to operate; others use an air gap or are immersed in a fluid, usually water, in order to better transmit the sound wave through a material. OKOS offers a large variety of transducers up to 300 MHz for different applications and can custom engineer transducers for specific applications to suit specific needs.
According to Polu, the OEM offers four general types of transducers (epoxy, PVDF, delay line, phased array), each of which has advantages for certain applications: Epoxy tipped transducers tend to be less than 30 MHz and are useful for imaging thick samples or samples with very
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