Modelling and characterisation of the polymer stud grid array(PSGA) package: electrical, thermal and thermo-mechanical qualification

摘要

We characterise the polymer stud grid array (PSGA) packageelectrically, thermally and thermomechanically for successful commercialapplication. For the electrical characterisation, we extract lumpedparameter RLC (resistance-inductance-capacitance) models for theinterconnects from simulations. We also measure the RF performance ofthe package on test structures and also by mounting an RF chip on thePSGA. The average self-inductance from the wirebond pad to the bottom ofthe stud is 1 nH and the capacitance to the ground is 0.35 pF for thePSGA with `Over The Edge' (OTE) interconnection. The lumped RLC modelverified by full 3D electromagnetic simulations and is found to be validat least up to 10 GHz. Simulation models also indicate that the`Micro-via' (μ-via) type of interconnection on the PSGA packageimproves performance by decreasing the inductance on an average by 60%.Thermal characterisation involves the development of a steady-statethermal compact model with 6 nodes for the 72-pin PSGA. We also performtransient thermal measurements on test packages to fine-tune thedetailed model. For the thermo-mechanical case we test the first leveland second level reliability by experiments and optimise them usingsimulations. The board level reliability for the 72-pin PSGA mounted ona PCB is very high (N50%>10000 cycles). Simulations also show ahigher reliability for the PSGA than the PBGA (plastic ball grid array)