Materials Science Forum Vol. 954

Abstract: Si/SiC heterostructural impact avalanche transit time (IMPATT) diode indicates of important applications in Terahertz (THz) power source, integrated circuit etc. In this paper, the (n)Si/(p)4H-SiC, (n)Si/(p)6H-SiC, (n)Si/(p)3C-SiC heterostructural double drift region IMPATT diodes operating at the atmospheric window frequency of 0.85 THz are designed by the drift-diffusion model while their static state, large signal and noise properties are numerically simulated. The performance parameters of the studied devices such as breakdown voltage, peak electric field strength, optimal negative conductance, output power, power conversion efficiency, admittance-frequency relation, quality factor, noise electric field, mean-square noise voltage per band-width and noise measure were calculated and compared. This method can guide for optimizing the Si/SiC heterostructural IMPATT device in the future.

Abstract: Power electronic devices are the basis of power converters, and excellent device performance improves that of power converters directly. In this paper we take SiC MOSFET CAS120M12BM2 (1200V/ 120A) and Si IGBT FF150R12KE3G (1200V/150A) as examples, which have the same voltage rating, to apply to the converters of urban rail vehicles, whose switching frequency, power density and efficiency are analyzed and contrasted. The results show that the switching frequency of the SiC MOSFET converter can be increased to 50kHz, at the same time its power density and efficiency are significantly higher than that of the Si IGBT converter.

Abstract: Silicon carbide (SiC) devices have been gradually applied in power electronic for the characteristics of high voltage, high power densities, elevated operating temperature and low switching energy loss. In this paper, a SiC MOSFET welding power module is proposed based on high voltage Si IGBT standard module structure to evaluate the thermal performance. The thermal lateral spread model expounds the expansion of the heat flow in the vertical crossing of a thermal conductor, and thermal resistance distributions of packaging materials in Silicon carbide and Silicon power module are studied through the COMSOL Multiphysics finite element software based on the thermal lateral spread model assumption that minute changes in thermal conductivity would produce no alterations in heat spreading angle. The result indicate that SiC MOSFET module gives the larger thermal resistance than the Si IGBT module with the same encapsulation structure but higher power densities for SiC, what’s more, the solder for die attach and direct bonding copper which include upper copper, substrate and lower copper contribute more thermal resistance in SiC MOSFET module. The differences of thermal Performance in SiC and Si modules can be obtained to benefit us in optimizing SiC MOSFET power module structure design and packaging materials selection.

Abstract: 1200V-450A IGBT power modules are fabricated in this paper. We study both the steady state and transient thermal performance of the IGBT assemblies by the finite element method using commercial software ANSYS Workbench to better understand the characteristic. Furthermore, power cycling tests indicate that inelastic strain increase as the numbers of cycles increase. In addition, X-ray photographs and ultrasound scan images were compared before and after the experiment. The thrust force of bonding wires decrease with increasing numbers of cycles, as indicated by tested.