Technology of packaging by Liquid Mold-Underfill (MUF) material for advanced mobile devices

As one approach of advanced packaging technologies, high reliability Liquid Mold UnderFill (Liquid MUF) materials and unique process will be presented here. Liquid MUF materials have the features of high adhesion, low CTE and low modulus. It is possible to alleviate the stress of the solder of each device mounted in the package, and they have excellent reliability too. These materials are adjusted the workability depending on the application. Moreover, because of low viscosity, the Liquid MUF material could be mold-underfilled with relatively lower stress to large Flip Chip devices with small gap and narrow pitch compared to the conventional solid materials. As for the processes of the liquid materials, printing, dispensing and compression molding are applicable. In this paper, the printing process, especially vacuum printing encapsulation systems (VPES) and pressure curing systems, will be mainly discussed. In addition, module package structure that achieved by these material and process development will be also explained in detail.