Analysis and Mitigation of Effect of Plating Stub on Transmission Waveform and Eye Diagram

Plating stubs inevitably form in the manufactured processes for ball grid array packages. This paper investigates how the plating stub affects the time-domain transmission (TDT) waveform and eye diagram. A scheme for mitigating the effect of the plating stub is also proposed. The effects of time-domain reflection noise generated by the plating stub on the TDT waveform are precisely studied using a lattice diagram. Simple and approximate formulas are developed to determine whether the eye diagram crosses the eye mask. With this determination, the maximum length of the plating stub can be estimated.