Abstract: A fine-pitch pin grid array for mounting an IC chip having a number of signal, ground and power contact pads thereon comprises a square as-fired ceramic substrate having a corresponding number of signal, ground and power metal filled vias located on the side portions of the surface thereof. Deposited on the surface of the substrate is a thin-film metallization which includes a corresponding number of signal, ground and power bonding pads located on the sides of the central portion thereof and further includes conductive traces which provide for connecting each signal metal filled via to a signal bonding pad. Deposited over the thin-film metallization is a multilayer circuit which includes a first dielectric layer having a low dielectric constant, a ground metal layer, a second dielectric layer having a high dielectric constant, and a power metal layer. The ground metal layer is used to commonly connect the ground metal filled vias to the ground bonding pads.

Abstract: An as-fired alumina substrate for a hybrid microcircuit formed of GaAs dies operating at gigahertz frequencies has a large number of about 0.013" diameter via holes drilled on the surface thereof by use of a laser. A metal filling in each via hole is formed with about 85% sintered tungsten and 15% copper reflowed into the pores thereof to provide a composition that has a thermal coefficient of expansion that substantially matches that of the GaAs dies and the alumina substrate and also provides for hermetically sealing the via holes. The alumina substrate is further provided with a ground plane by which it is mounted on a metal block serving as a heat sink. The high frequency GaAs dies mounted on the via holes use the metal fillings therein to carry their internally generated heat to the heat sink and to provide low inductance ground paths for the microcircuit.