Viscoelastic analysis of multistage stacked via structure in build-up substrate

Compact high density electronic equipment is achieved using the stacked via technology in a build-up substrate. In order to design the build-up substrate, the impact of the viscoelasticity behavior of insulating resin under heating and cooling must be considered. This paper investigates how to predict the stacked via fatigue life using a viscoelastic analysis. The thermal cycle test, elastic analysis and the viscoelastic analysis were conducted in eight variations of stacked via structure including either of two resins. Either three, four, five, or six build-up via (BU via) were stacked on the plated-through hole (PTH) in these structures. As a result, the viscoelastic analysis agreed well with that of the thermal cycle test in any stacked via structure.