Study of dielectric materials coating conformality and adhesiveness on epoxy mold compound surface

Dielectric material coating process on the surface of epoxy mold compound has been successfully developed for fan-out wafer level packaging. This paper introduces the pretreatment process and conditions required for dielectric coating, coating process and the studies of dielectric material coating conformality and adhesiveness on epoxy mold compound, silicon and copper surface. The DOE of these film deposition process parameters was performed to develop the pretreatment process conditions for dielectric. Coating conformality was studied here to decide the optimized conditions. 250μm solder bump reflowed on UBM is the test structure to examine the strength of the dielectric adhesion on the silicon and epoxy mold compound surfaces through shear test. This shear test results is compared with the similar test structure which the dielectric material was coated on the copper surface built-on silicon substrate. Failure mode analysis using microscope is carried out to evaluate the bonding strength of individual layers. A further evaluation on the reliability of solder joint, dielectric adhesiveness and failure mode will be performed. [1], [2]