Abstract
We developed a new flip-chip process called NSD (Non-Conductive Adhesive Stud-Bump Direct Interconnection) method. First, a resin encapsulation sheet is attached to the substrate by heat compression. Stud-bumps are formed on an IC chip by means of conventional wire-bonding technology. The chip is then attached to the substrate. Finally, the encapsulation film is heated and compressed using a heating tool, during which the stud-bumps contact the electrodes on the substrate to form electrical interconnections that follow the substrate warp. When the encapsulation film cools, a compression force is generated between the IC chip and substrate, thus maintaining the interconnections. Highly reliable interconnections were obtained by optimizing the encapsulation film properties using the Finite Element Method (FEM). We report on the relationship among the encapsulation film properties, the reliability and Von-Mises stress amplitude. Applied case to the stacked package and the ultra-thin type module is described.
