Measuring Reflective Surfaces
High reliability requires measurements in multiple directions.
By: Dr. Subodh Kulkarni, CyberOptics CEO (as published on Semiconductor Engineering)
Manufacturers are adopting automated optical inspection (AOI) systems based on phase shift profilometry (PSP) for applications in advanced packaging processes. Many of these processes use front end-like techniques to create connections among die within a package and from the packaged die to the outside world. The technique offers fast, precise measurements of the 10µm to 100µm features that are typical of these middle-end manufacturing processes. Some of the materials and features, such as silicon wafers, glass substrates, solder bumps and pillars, and more, have specularly reflective (mirror-like) surfaces that present special challenges.