CAD model reconstruction of solder balls for the computationally efficient electromagnetic field simulation

In this paper three different methods for reconstructing CAD models of solder balls based on 3D computed tomography (CT) data are discussed. The resulting CAD model contains accurate geometrical data of the device which can be used for an electromagnetic field simulation using the finite difference time domain (FDTD) method. This allows a non-instrusive evaluation of the electrical parameters of passive circuits, in this case for solder balls or bumps. All three reconstruction methods presented here will result in simulation meshes with a significantly reduced number of mesh cells compared to a simulation directly based on the original CT data. This leads to a significant reduction of both memory usage and simulation time which is important for complex packages.