Contents Introduction
As the drive for increasing functional density in packages converges with greater mass production of electronic devices, the task of addressing the growing thermal challenge in packaging requires consideration for existing established packaging designs [1]. Thermal management strategies that are designed around the conventional flip-chip BGA and Quad-Flat-No-Lead (QFN) packaging structures can effectively leverage them as a test-bed for potential thermal improvements in future packaging structures. One such focus is the advances in improving the thermal properties of packaging materials, from thermal-interface-materials (TIM) to underfills, die-attach (DA) materials and mold encapsulation. For flip-chip packaging, previous studies show the configurable role that Thermal Interface Material (TIM) plays in the package's thermal performance with a focus on thickness, thermal conductivity and coverage parameters [2], [3]. Experimental characterization also reveals actual realworld performance differences in adhesive vs gel-based TIMs. Furthermore, underfill studies indicate significant impact for thermal performance, with regards to board-level underfill [4]. In QFN packaging, previous studies on die-attach (DA) material describe impact on thermal resistance from the DA bondline thickness to type of voids [5], [6]. Mold compound findings consider the encapsulation as an obstacle in the thermal path from die to heat sink, with thinner mold and higher thermal conductivity clearly playing a noticeable role in improving thermal performance [7].
