Reactive flow simulation in transfer molding of IC packages

Transfer molding is currently the most widely used process for encapsulating integrated circuits. Although the process was introduced over 20 years ago, generating billions of parts each year, it is far from being optimized. With each new mold, molding compound, and device, lengthy and expensive qualification runs have to be performed to minimize defects ranging from incomplete fill, part-non-uniformity, wire sweep, and voids. Testing is carried out more on a trial-and-error basis than by following some heuristic process guidelines. This paper describes how reactive flow simulation can be applied to transfer molding to yield acceptable design and processing parameters. The non-isothermal filling of non-Newtonian reactive epoxy molding compounds in a multi-cavity mold is analyzed and modeled. Analysis is conducted to investigate the influence of process deviations on the final molded profile. The rheological and kinetic behavior of a low-stress compound used for encapsulating ICs is studied