Flip chip interconnect analysis at millimetre wave frequencies

This paper examines the variation of RF performance on a flip chip due to changes in bump height, bump position, bump shape and number of bumps per interconnect. A full 3D electromagnetic simulator is used extensively to compute the scattering parameter response, impedance and electric field distributions. Varying the bump height will change the reflection coefficient and return loss at millimetre wave frequencies significantly. It is found that proper bump positioning could improve the return loss of the structure. Different bump shape also affects the RF performance of the flip chip. Tapered bump shape gives the best return loss and the lowest reflection coefficient.