Patent ID: 6891392

Claim:
A probe structure for testing impedance of a package substrate using time domain reflectometry, the probe structure comprising: a connector for electrically connecting the probe structure to a time domain reflectometry tester, the connector having a signal conductor and a ground conductor, an electrically conductive cantilever signal pin electrically connected to the signal conductor, the electrically conductive cantilever signal pin having a tip for making an electrical connection with an electrically conductive structure to be tested on the package substrate, the electrically conductive cantilever signal pin electrically isolated by and sheathed within a ground shield that is electrically connected to at least one of the ground conductor and electrically conductive cantilever ground pins, where the around shield is disposed coaxially along substantially an entire length of the signal pin with just the tip of the signal in extending from the around shield, and the electrically conductive cantilever ground pins electrically connected to the ground conductor, the electrically conductive cantilever ground pins having tips for making electrical connections with electrically conductive structures on the package substrate that surround the electrically conductive structure to be tested on the package substrate.