Electrical characteristics of 25 mil pitch JEDEC PQFP surface mountlead frames for multichip modules

摘要

The electrical characteristics of the leadframe used to form theJEDEC standard 25-mil-pitch PQFP (POLYHIC quad flat pack) outlinepackage are examined. The characteristic impedance is computed and threemodels of the leadframe pins are created for each ground configurationcase for both isolated and coupled pairs of pins. Crosstalk betweenadjacent pins has been simulated and measured as a function of signalrisetime. The risetime degradation of signals transmitted through theleadframe pins has been simulated and measured. These data have beenused to estimate a conservative upper limit for clock and data ratecapability of this leadframe. The POLYHIC PQFP outline package is shownto be a multi-gigabit-per-second package