Silicon-Carbide (SiC) power devices have become a promising option for traditional Silicon (Si) due to the superior material properties. To fully take advantage of the SiC devices, a high-performance power device packaging solution is necessary. This study proposes a cost-effective double-sided cooled (DSC) 1.2 kV SiC half-bridge power module using organic epoxy-resin composite dielectric (ERCD) substrates. The high mechanical and thermal performance of the power module is achieved by the low-modulus, moderate thermal conductivity, and relatively thin (120 μm) layer of ERCD material compared with traditional metal-clad ceramic approaches. This novel organic dielectric can withstand high voltage (5 kV @ 120 μm) and operate up to 250°C continuously, which is indispensable for high power applications. The thermal modeling results show that the equivalent thermal resistance junction-to-case (Rjc_eq) of the DSC power module using dual direct bonded copper (DBC) is 17% higher than the dual ERCD configuration. Furthermore, a non-insulated DSC power module concept is proposed for maximizing thermal performance by considering thermal vias in the ERCD substrate and direct-soldered heat sink. A thought process for optimization of thermal via design is demonstrated and it shows up to 24% of improvement on thermal performance compared with the insulated DSC power module.
As mentioned before, many implants have motion between their elements which causes wear of the implant parts. Consequently, the effect of corn cob weight fraction on the tribological properties of the PLA composites was investigated. Studying the tribological properties of any material is conducted by exploring the friction coefficient of the material and the specific wear rate . The PLA-CC composites were rubbed under a normal applied load between 5 to 20 N against a stainless-steel counterpart. The friction coefficient average was estimated, as shown in Figure 14.
Usually, biomedical implants are designed to work for long periods. Consequently, they should withstand the load if there is a relative motion between the implant components. Therefore, in the current study, the friction coefficient of PLA-CC composite was investigated under 20 N normal load for different sliding times 5 to 20 min that, represents 120 to 480 m, as shown in Figure 15. Increasing sliding distance led to a decrease in the friction coefficient but with the same behavior for the composites where PLA-CC10 recorded the lowest friction coefficient at different sliding distances. The decrease in the friction coefficient could be attributed to the smoothness in the sample surfaces due to the rubbing for a long distance, and the abrasion occurred against the counterpart. Dass et al.  claimed that when polymers rubbed for long periods against steel disks, the generated heat could lead to a localized melting for the polymeric samples; in which a thin film from the polymeric material transmits to the steel counterpart working as a third body between the rubbed surfaces causing a decrease in the friction coefficient. Furthermore, the mechanical properties of the PLA-CC showed an enhancement in the load-carrying capacity, and the enhancement of the load-carrying capacity decreases the friction coefficient of the material . To verify the load-carrying capacity based on the frictional process, the stresses generated during the tribological test were recorded using ANSYS software based on the model in Section 2.3.2. Figure 16 shows the equivalent and maximum shear stresses along the PLA-CC composite samples due to the friction under normal load of 20 N. For all composite samples, the maximum equivalent and shear stress appear at the composite edge where the direction of friction could be identified. Figure 16 illustrates that PLA-CC10 has the lowest contact stresses among other composites, indicating that it has the highest load-carrying capacity. This result is in line with the mechanical properties that showed the highest ultimate strength for PLA-CC10 besides the lowest friction coefficient. 2b1af7f3a8