Thermal modeling of wire-bonded power modules considering non-uniform temperature and electric current interactions

Abstract

To assess power devices' reliability, it is crucial to have a relatively accurate thermal approach which provides valid temperature estimates. In this paper, for two commonly used Si IGBT and SiC MOSFET power modules, the electric current-induced effects on bond wires and the correlation between the non-uniform temperature distribution and electrical conductivity of the sensitive constituent materials are studied. In addition, a more realistic active area of the modules is defined by excluding inactive regions, i.e., the gate area, gate runners, and termination ring. Also, the electric current distribution among parallel bond wires attached to the dies' metalization pads is investigated. Comparisons made between an approach which includes all the above aspects with a conventional one where uniform heat is injected into semiconductor dies, although showing acceptable error in Si IGBTs, result in a very significant difference in SiC MOSFETs.

Effect of Current Distortion and Unbalanced Loads on Semiconductors Reliability

“…For the inverter analyzed, a power module based on SiC MOSFETs is used. From the analyses performed by different authors, [42]- [47], it is clear that the number of cycles to failure, Nf, is closely related to the average junction temperature, Tjm, and the junction temperature swing, ΔTj.…”

Trade-offs Between Gate Oxide Protection and Performance in SiC MOSFETs

“…The simulations in this investigation show a marginal temperature increase and its impact on the lifetime of the packaging will be difficult to quantify. Finite element simulations [36] can be paramount for understanding the impact of these small junction temperature changes on the packaging stresses.…”

Non-uniform Temperature Distribution Implications on Thermal Analysis Accuracy of Si IGBTs and SiC MOSFETs

“…In Fig. 1, typical static electric current-voltage (I-V) curves of semiconductor devices are shown at different temperatures [11]. It can be seen that in the positive temperature coefficient (PTC) region, the higher the temperature of the semiconductor die, the lesser the electric current density, hence power loss.…”

“…Such a high htc parameter almost makes a constant temperature equal to the ambient temperature at the backside of the baseplate. Also, the ambient temperature is defined as 25 C., the temperature dependency of thermal conductivities is taken into account because they might cause temperature errors to a few degrees [18]. Table 1 lists the characteristics of the constituent layers for each module as well as the temperature-dependent thermal conductivities for the thermo-sensitive layers.…”