HIGH-SPEED ELECTRICAL CHARACTERIZATION AND SIMULATION OF A PIN-GRID-ARRAY PACKAGE

A 181 pin Pin Grid Array (PGA) was characterized using time and freque ncy domain techniques to identify major sources of signal degradation, The pins, as well as a layer of plating lines that was included for e lectroplating the exterior metal surfaces, were found to have a delete rious effect on the signal transmission within the package, In additio n, a ground delay resulting from the separation of the signal pin and its nearest ground pin was seen to cause significant degradation in si gnal lines whose pin was far from a ground I/O. For signal lines that are geometrically equivalent due to package symmetry, this effect was seen to increase with increasing signal/nearest ground pin distance, r esulting in as much as a 79% increase in the package risetime in some lines, These effects were simulated using a model whose elements were based on actual physical structures within the package and whose param eters were derived from experimental measurements.