Fluid/Structure Interaction Analysis of the Effects of Solder Bump Shapes and Input/Output Counts on Moulded Packaging

This paper presents a fluid/structure interaction (FSI) analysis of the effects of solder bump shapes and input/output (I/O) counts on moulded packaging. The FSI events during the encapsulation process are investigated using a virtual modeling technique, whose mesh-based parallel code-coupling interface couples both finite volume and finite element codes. In this paper, the effects of five different solder bump shapes, denoted Cases 1-5, are considered in the perimeter and full array of solder bump arrangements with different I/O counts. The FSI between the epoxy moulding compound and structures (silicon chip and solder bumps) is presented in the displacement profile. The effects of the bump shape and I/O count are considered in the flow front advancement, structure displacement, stress, and void formation. The maximum displacements, von Mises stresses, and voids are minimized by implementing the bump shape in Case 3. The applications of Cases 3 and 5 with higher I/O counts (full array type) reduced the stress concentration in the solder bump by nearly 40% and 60%, respectively, compared to the cases with lower I/O counts (perimeter type).