Effective Evaluation Method: A New Delamination Test Method for MUF (Molded Underfill) Package

Abstract

Molded underfill (MUF) is one of the most effective molding technologies in the advanced packaging industry. Developing highly reliable MUF is still challenging due to all basic requisitions of semiconductor packaging. Among all these requirements, controlling interfacial delamination between materials in integrated circuits (IC) packages has been considered to be the most important challenge to be achieved. Even though there are many efforts to characterize the package delamination, an effective method to speculate the delamination has not been well established. Herein, we introduce an effective and reliable evaluation method to characterize and predict the interfacial delamination and cohesive failure under mechanical and thermal stresses. The delamination temperature of moisturized EMC package is defined at the fluctuated thermal mechanical analysis (TMA) signal point which is proportionally correlated to the delamination of real packages. Based on this result, we established the equation of package delamination with the result of package curvature by TMA and package warpage by shadow moire at 20 and 260°C. The package delamination temperature can be simply calculated by using general epoxy molding compound's properties, such as global dimension change and storage modulus from TMA and dynamic mechanical analysis (DMA) respectively. The package delamination temperature calculated by the equation is well matched with the actual package delamination temperature detected by infrared reflow method. In this paper, we will address details of theoretical backgrounds of the equation and introduce a new method for detecting the delamination temperature of packages. This novel evaluation method is able to develop and optimize a highly reliable epoxy molding compounds for MUF package.