High Temperature SiC Embedded Chip Module (ECM) with Double-Sided Metallization Structure

The work reported in this dissertation is intended to propose, analyze and demonstrate a technology for a high temperature integrated power electronics module, for high temperature (e.g those over 200C) applications involving high density and low stress. To achieve this goal, this study has examined some existing packaging approaches, such as wire-bond interconnects and solder die-attach, flip-chip and pressure contacts. Based on the survey, a high temperature, multilayer 3-D packaging technology in the form of an Embedded Chip Module (ECM) is proposed to realize a lower stress distribution in a mechanically balanced structure with double-sided metallization layers and material CTE match in the structure. Thermal and thermo-mechanical analysis on an ECM is then used to demonstrate the benefits on the cooling system, and to study the material and structure for reducing the thermally induced mechanical stress. In the thermal analysis, the high temperature ECM shows the ability to handle a power density up to 284 W/in with a heat spreader only 2.1x2.1x0.2cm under forced convection. The study proves that the cooling system can be reduced by 76% by using a high temperature module in a room temperature environment. Furthermore, six proposed structures are compared using thermo-mechanical analysis, in order to obtain an optimal structure with a uniform low stress distribution. Since pure Mo cannot be electroplated, the low CTE metal Cr is proposed as the stress buffering material to be used in the flat metallization layers for a fully symmetrical ECM structure. Therefore, a chip area stress as low as 126MPa is attained. In the fabrication process, the high temperature material glass and a ceramic adhesive are applied as the insulating and sealing layers. Particularly, the Cr stress buffering layer is successfully electroplated in the high temperature ECM by means of the hard chrome