Failure mechanisms of microwave (MMIC) packaging

摘要

Thermo-mechanical failure mechanisms of microwave ceramic packaging is reported. The effect of die attach processing parameters on GaAs monolithic microwave integrated circuit (MMIC) channel temperature and die themo-mechanical interface stability has been investigated Finite Element Analysis (FEA) methods were used to simulate the dynamic stresses that are produced in the MMIC devices when they are subjected to power cycling, thermal cycling or thermal shock. FEA was further used to study theeffects of die attach voids on peak surface temperature and on the Von Mises and shear stress in each of the device layers. The shear stress typically initiated horizontal cracks at the die-attach interface, while the normal stress initiated verticalcracks. Voids beneath the location of the power transistors were found to significantly increase the thermal resistance resulting in an increase in device surface temperature. Localized regions of attach voids may also lead to burnout type of catastrophic failures. Scanning Infrared Microscope (SIM) was used to determine the thermal surface temperatures while Scanning Acoustic Microscopy (SAM) was used to identify nondestructively voids at the die substrate interface.