Use of optical technique for inspection of warpage of IC packages

Abstract

The packaging of IC packages has changed over the years, from dual-inline, wire-bond, and pin-through-hole in printed wiring board technologies in the 1970s to bali grid array, chip scale and surface mount technologies in the 1990s. Reliability has been a big problem for manufacturers for some moisture-sensitive packages. One of the potential problems in plastic IC packages is moisture-induced popcorn effect which can arise during the reflow process. Shearography is a non-destructive inspection technique that may be used to detect the delamination and warpage of IC packages. It is non-contacting and permits a full-field observation of surface displacement derivatives. Another advantage of this technique is that it is able to give the real-time formation of the fringes which indicate flaws in the IC package under real-time simulation condition of Surface Mount Technology (SMT) IR reflow profile. It is extremely fast and convenient to study the true behaviour of the packaging deformation during the SMT pro cess. It can be concluded that shearography has the potential for the real-time detection, in situ and non-destructive inspection of IC packages during the surface mount process.