Optimization of solder joint configuration in multi-chip packaging system

Abstract

Packaging engineers, in the search for the perfect packaging technology, are turning to three-dimensional packaging technologies that stack multiple dies/chips within a single package. Prevailing problems with stacked dies and clips are the tilting of the chips or clips due to the unbalanced bond line thickness of different solder attachments at different height levels or unbalanced weight distribution of the components inside the package. This could be a result of offset pads or inaccurate solder volume which results to uneven BLTs or solder joints, which all boils down to not having adequate modeling tools at hand to foresee potential tilting issues in a complicated solder joint system constrained in one package. This paper addresses this issue by utilizing an FEA modeling tool that can model the solder joint system of any stacked or clip packages. The tilting of the die is successfully modeled and the BLT predicted correlates well within the actual result. The mechanism of chip tilting was investigated and correlated with actual cross-section result. The availability of the modeling tool to successfully model multi-body solder joint system is a breakthrough in package tilting modeling efforts. Optimization of the solder joint system of any package is now possible with the Tool.