MANUFACTURING
images are then analysed to detect and characterise flaws such as cracks, inclusions, and voids,” says Polu.
With the rising demand for batteries in the market, there is now a need for an automated method to inspect all batteries during the manufacturing process. The challenge, however, is performing 100% inspection at sufficient throughput speeds to remove materials with defects that do not meet strict quality requirements. As with other inspection systems, increasing scanning speed traditionally meant sacrificing scanning image resolution.
Fortunately, recent advancements in SAM technology have significantly improved throughput speeds and defect detectability. “While a conventional 5 MHz sensor could take up to 45 minutes to inspect a battery’s components, an advanced phased array with 64-128 sensors and innovative software to render the images reduces inspection time to five minutes with more granular detection of small impurities or defects,” says Polu. By dramatically increasing inspection speed, Polu says the battery industry is no longer limited to selective sample testing during In-Process Quality Control. Although SAM has
Battery manufacturers are increasingly integrating SAM inspection tools into their process to catch defects at an early stage.
Scanning Acoustic Microscopy (SAM) inspects batteries for microscopic cracks, defects, separations and delaminations.
long been utilised for this type of inspection, the testing involved a handheld unit or a multi- point inspection. Now it is more feasible to conduct 100% inspection of the entire surface/ interface. In addition, these advances also facilitate the detection of not just gross defects, but much smaller defects, to drive highly consistent, high yield products.
“Advanced, phased array SAM systems make it possible for battery manufacturers to move to a higher level of failure analysis because of the level of detection and precision
involved,” says Polu. “In the past, detecting a 500-micron defect was the goal; now it is a 50-micron defect. And with batteries integral to increasingly important products like electric vehicles and battery energy storage systems, they want to inspect every item, not just a few samples.”
When high throughput is required for 100% inspection, ultra-fast single or dual gantry scanning systems are utilised along with 128 sensors for phased array scanning. Multiple transducers can also be used to simultaneously scan for higher throughput. “In tests, the equipment can now scan batteries over ten times faster,” says Polu. As important as the physical and mechanical aspects of conducting a scan, the software is critical to improving the resolution and analysing the information to produce detailed scans. Multi-axis scan options enable A, B, and C-scans, contour following, off-line analysis, and virtual rescanning for batteries, which result in highly accurate internal and external inspection for defects via the inspection software. “OKOS decided early on to deliver a software-driven, ecosystem-based solution,” said Polu. The company’s ODIS Acoustic Microscopy software supports a wide range of transducer frequencies from 2.25 to 230 MHz. Polu estimates that the company’s software- driven model enables them to drive down the costs of SAM testing while delivering higher quality inspection results at faster speeds. “With more sensors and advanced software to interpret the information at very high resolutions, battery OEMs can inspect 100% of the materials utilised at a level one to two orders of magnitude better to discover flaws that were previously undetected. This will increasingly become the industry’s best-in- class standard,” concludes Polu.
By Del Williams
Del Williams is a technical writer based in Torrance, California.
APRIL 2024 | ELECTRONICS FOR ENGINEERS
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