Accurate measurement of ground-ring inductance in ball grid arraypackage

A new technique has been developed to measure the ground-ring inductance in a ball grid array (BGA) package. A simple parallel LC circuit is used to model the ground-ring parasitics at frequencies up to 1 GHz. After connecting an SMA connector to the ground ring of the BGA package, a network analyser can be used to measure the reflection coefficient (S₁₁) up to 1 GHz from which the ground-ring inductance can be extracted. It has been found that the ground-ring inductance depends very strongly on the phase of S₁₁. This leads to the advantage of excellent accuracy for the extracted quantities. The experimental ground-ring inductance data for a variety of BGA packages are verified by Ansoft simulation results