Reliability Design and Optimization Process on through Mold via using Ultrafast Laser

Abstract

In this study, a through mold via (TMV) process using ultrafast Laser has been developed for the interconnection on 3D package-on-package (PoP) application. Epoxy molding compound (EMC) is a composite material consisted of epoxy resin, filler particles (fused silica) and other constituents. Among these chemical compositions, the size and spatial distribution of fillers on the EMC dominate the sidewall quality on drilled trench. However, random filler leakage on the sidewall leads to an irregular and uneven trench and these drop out fillers become a problem needed to be solved. Faster removal of debris can be achieved by controlling the laser drilling parameters. Parametric studies have been performed to determine the specification of trench and design rule of material. The optimal desmear process on TMV bottom PoP package developed in this study demonstrates the reliability improvement on follow-up sputtering or filling process.