Laser Ultrasound-Interferometric System for Packaged Electronic Devices Quality Evaluations

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This grant provides funding to develop a novel quality inspection system that will evaluate the defects in packaged electronic devices. Such defects would include misaligned, short, missing, cracked, voided, delaminated, partially connected, open, excessive and starved solder bumps that occur in such packaged devices as flip chip (with no underfill), direct chip attach (DCA), chip scale packaging (CSP), and cracks in chip capacitors and resistors. The PI proposes to develop an automated laser ultrasonic-interferometric system that uses a single optical fiber for evaluating the quality of packaged electronic devices. This system can be used in a production line as a go/no-go inspection tool, or off-line during process development for process optimization. This will be a high resolution, non-contact, non-destructive, low cost, fast and accurate quality inspection system. The PI will also develop a signal processing procedure for determining the presence of one or more of these defects. A finite element analysis model will be developed to explain the experimental results. The final objective is to use the experiences gained in the conduct of this study to build an industrial grade prototype system for use as a Beta test in industry. The PI and his students will swiftly transfer this technology to the industry. This research will result in the development of a novel and automated non-contact, non-destructive, fast, sensitive, accurate and low cost solder bump quality inspection system. It is also expected to be applicable to many types of surface mount devices such as chip resistors and capacitors, and conventional lead frame packages, making it a versatile and cost-effective automated manufacturing tool. This tool could be used on-line as a go/no-go inspection tool, and off-line during process development for process optimization. Use of this new Laser Ultrasound-Interferometric inspection technology for automated manufacturing inspection will bring tremendous cost savings by catching defects early in the process. With access to rapid, accurate inspection systems, cost savings will also be realized in process development by reducing the time to market new products, and allowing better process optimization before manufacturing ramp-up. If the research objectives are fully implemented, the proposed technique will help to increase the yield of DCAs, flip chips, CSPs, silicon chips, and chip resistors and capacitors. The research will impact the nation's human resources by training these students in the development and application of low cost and high performance sensors, for on-line and off-line quality evaluation of microelectronic packaging devices. The students who will be participating in this research will learn how to carry out applied and fundamental research in microelectronic packaging, on laser ultrasound, on optical techniques, on system integration, on signal processing and on finite element modeling. They will also learn about technology licensing and commercialization