Versatile Metrology Platform for FOWLP PoP Manufacturing Process Control

Package-on-Package (PoP) has many advantages, small foot-print, better performance, easier to debug, and better control over supply chain, etc. Recently PoP integration architecture based on fan out wafer level package (FOWLP) and through mold connection (TMC), demonstrated and many back-end manufacturing houses completed the qualification and migration to this architecture. Despite the cost and performance benefits with this new architecture, the assembly process is complex. Traditional SMT process for chip-attach and die attach are being leveraged but require close monitoring. The registration and volume of screen-printed materials, solder paste and solder flux need stringent control. The accuracy requirement for die placement coupled with thin die handling challenges warrants continuous monitoring for this process step. Further, TMC formations, laser drilling, and bumping require close monitoring. To address these metrology challenges, Koh Young developed a versatile sensor, rapid area scan interferometer (RASI), an area scan interferometer that can measure thickness and volume on all kinds of materials, highly reflective, diffusive, opaque, semi-transparent, and transparent materials. The sensor has measurement repeatability in nanometers at the same time RASI innovative instrumentation provides inspection speed that exceeds throughput requirements of IC package assembly line.