Inspection of Flip-Chip Epoxy Underfill in Microelectronic Assemblies Using Compensated Laser-Based Ultrasonic Receivers

摘要

In the industrial community, there is a need for process control and inspection tools that can improve the efficiency, yield and performance of various manufacturing processes including bonds, surface treatments, case hardening, composites, metallurgy, microcrack detection, adhesion, remote temperature and thickness measurements. By performing the inspection on-line and in real-time, the possibility exists for closed-loop, in-process control. This can lead to reducing cost, labor, scrap, and machine downtime. Conventional ultrasonic methods can be employed to diagnose many materials, in that their acoustic properties are typically functions of the parameters to be ascertained. Present techniques, such as liquid immersion, jet-spray approaches, air-coupled and direct transducer contacting may be of limited use in many process-control applications, including those involving vacuums, high temperatures, plasmas, and workpieces with highly structured and complex surfaces.