• • • DEFENCE TECHNOLOGY • • •
ENSURING HIGH RELIABILITY IN AEROSPACE MATERIALS AND
ELECTRONICS WITH SAM Scanning Acoustic Microscopy (SAM) has become a critical non-destructive testing method for confirming high reliability in aerospace and defense applications by detecting hidden flaws and validating material integrity By Jeff Elliott, Torrance, California-based Technical Writer
n aerospace and defense, the electronics and materials incorporated into satellites, aircraft and defence platforms are expected to function in conditions that push the limits of materials science and engineering design. Unlike consumer- grade devices, which may tolerate minor faults, aerospace devices cannot afford a single unexpected failure, since mission success and human safety depend on consistent performance. This principle forms the foundation of a high-reliability approach, an engineering philosophy focused on designing and manufacturing systems, components and processes that must perform dependably under mission-critical or extreme conditions. Such conditions may include severe temperature fluctuations, intense mechanical shock and vibration and corrosive environments. Achieving high reliability in aerospace and defense requires the deliberate selection of specialised materials coupled with durability-focused design practices to ensure structural and electrical integrity when subjected to extreme stress. To counter continuous vibration and sudden mechanical shocks, components are often housed in metal enclosures, and their materials are
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selected for their proven resistance to fatigue and cracking under dynamic loads. High-reliability components may also incorporate specialised coatings and corrosion-resistant alloys that protect against moisture, salt and fuel vapors. To withstand prolonged mechanical and environmental stress, materials are layered and bonded in a way that helps prevent delamination and surface fractures. However, even with the most advanced designs and high-performance materials, tiny flaws in electronic assemblies or structural components can trigger system-wide failure once in operation. Hidden defects such as microscopic voids in solder joints, delamination within composite structures, or cracks in semiconductor packages may remain undetected during fabrication. When subjected to the extremes of vibration, thermal cycling, or radiation, such flaws can compromise the entire system. Testing is, therefore, an essential element of high reliability to ensure potential weaknesses are identified, functionality is verified, and systems demonstrate lasting dependability prior to deployment. This is where nondestructive evaluation methods become indispensable.
Ultrasonic NDT
Ultrasonic non-destructive testing (NDT) has long served as a core inspection method within the aerospace and defence sectors. This technique employs high-frequency sound waves to detect even the smallest defects in components or assemblies without inflicting any damage. By transmitting these sound waves into electronic materials and structures, ultrasonic inspection can expose hidden internal flaws that would not be visible through external examination alone. Scanning Acoustic Microscopy (SAM) is a more specialised ultrasonic method that uses much higher frequencies, usually between 50 megahertz and several gigahertz.
“SAM extends defect detection to an entirely new scale: scans that were once limited to 500-micron flaws can now reach down to 50 microns, exposing imperfections that previously went undetected,” says Hari Polu, President of PVA TePla OKOS, a Virginia-based manufacturer of SAM and industrial ultrasonic non-destructive (UT-NDT) systems.
Unlike conventional ultrasonic NDT, which is used to detect flaws in large components with complex shapes, SAM is designed to generate highly detailed acoustic images of microstructures and stacked flat layers.
“SAM’s high-frequency operation delivers exceptional resolution at the micron or sub-micron level, a precision best suited for analysing thin samples and layered microstructures,” says Polu.
SAM applications in
electronics and metals In the semiconductor and electronics industries, the need for non-destructive failure analysis and reliability testing is accelerating. As a result, SAM equipment has evolved and is now being used to detect subsurface flaws, dis-bonds, cracks and other irregularities in these types of materials that constitute the ‘packaging’ of semiconductor components.
Beyond the semiconductor components themselves, today’s electronics products contain various specialty metals, alloys, plastics and glass components. All semiconductor components need to be enclosed and packaged in consumer usable form factors. As a result,
12 ELECTRICAL ENGINEERING • NOVEMBER 2025
electricalengineeringmagazine.co.uk
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