The Polymer Stud Grid Array (PSGA) Package: Test and Electrical Characterization for RF Applications

摘要

We study the RF electrical performance of the new 72 pin Polymer Stud Grid Array (PSGA) Package. This work demonstrates three types of test structures used for electrical evaluation of the package from 1 GHz to 10 GHz. These are PCBs (Printed Circuit Boards) using microwave substrates with coplanar transmission line patterns, test patterns fabricated on glass wafers using the IMEC's (Interuniversity Microelectronics Center) MCM-D (Multi Chip Module-Deposited) thin film technology and a demonstrator board with an RF chip packaged using the PSGA. Lumped element RLC (Resistance-Inductance-Capacitance) models are developed by extracting these parameters from simulations. The average self-inductance from the wirebond pad to the bottom of the stud is 1 nH and the capacitance to the ground is 0.35 pF for the PSGA with 'Over The Edge' (OTE) interconnection. The lumped model is verified by 3D electromagnetic simulations and is found to be valid at least up to 10 GHz. Basic through line measurements on the glass substrate show much better performance compared to the measurements on the PCB, thus making de-embedding easier and improving accuracy. Simulation models indicate that the 'Micro-via' (μ-via) type of interconnection on the PSGA package improves performance by decreasing the inductance on an average by 60%.