Numerical fluidic-chemical multi-physics simulation of a mass production model for electroless plating of fine-pitch interconnections in a microchannel for chip packaging applications

Abstract

Current chip packaging technologies for fine-pitch interconnections require high heat and pressure which could lead to failures on the surrounding delicate parts in the scaling-down process. By using electroless plating instead, these limitations could be avoided which already has been demonstrated in various experiments. However, the transition from experiments in the laboratory to the industrial fabrication has to face various challenges. A numerical multi-physics model to investigate the fluidic-chemical aspects while scaling-down the geometry for a possible mass production is developed. By the usage of this model, possible limitations, theoretical requirements and optimizations on the packaging system can be estimated and investigated. The results show that the pressure gradient of the model follows Darcy's law for porous medium. Furthermore, pillar couplings with gap usually have a non-uniform grow behavior. This non-uniformity can be optimized by applying a dome-shaped pillar-tip. Moreover, the convectional flux is in most of the samples of the domain dominant. Only by approaching the reactions surface, diffusion becomes a relevant part of the mass transport. The investigation of the Cu-ion concentration gradient shows that more Cu-ions are consumed while scaling down.