During the operation of an LED array, its thermal and optical performances are always not equal to the superposition of the individual LED's characteristics because of a significant thermal coupling effect between the arrays. Based on this, this paper proposes an electrical–photo-thermal model, with considering both junction temperature and luminous flux, to predict the both the thermal and optical performances of LED arrays operated under different currents, case temperatures, and lighting methods. The junction temperature and luminous flux of a single LED operating under different driving currents and case temperature conditions are firstly collected to establish the luminous flux response surface model of a single chip. Then it is used to predict the luminous flux of an array, whose junction temperature is predicted using both thermal coupling matrix (TCM) and numerical models. Experiments verify the luminous flux of the LED array under different operation conditions and show that the proposed electrical–photo-thermal modeling can be used to predict the thermal and optical parameters of LED arrays with 95 % accuracy. Thus, it is effective for the fast prediction of the junction temperature and luminous flux of large LED systems with array structures, i.e. intelligent automotive lightings and displays.

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Thermal management has always played a significant role in power module design. Double-sided heat dissipation is more efficient at transferring heat than the traditional package. Although there are several thermal modeling approaches to power modules, the application of the numerical models, which are computationally fast and accurate, has rarely been investigated for double-sided heat dissipation scenarios. This paper proposes a numerical heat conduction model of a double-sided heat dissipation power module with multiple chips embedded. The model was developed by solving Laplace’s equation for the temperature distribution of steady state heat transfer using the separated variable method. The individual chip placement, two-chip distance and orientation, and four-chip placement were discussed through this modeling approach. The optimal layout was found. Then, a half-bridge topology module that consisted of two chips was investigated. To verify the accuracy of the numerical model, Finite Element Analysis (FEA) of the model was performed using the same boundary conditions. The experiments were applied on the power cycling tester to extract the junction temperature and case temperature. The numerical methods show good temperature prediction accuracy compared to both FEA and experiments.@en

Double-sided packages for heat dissipation are an efficient thermal management mechanism for power semiconductor devices. A fan-out panel-level packaging (FOPLP), as one of the double-sided forms, exhibits excellent electro–thermal characteristics and provides low stray inductance and thermal resistance. Besides, the temperature at each point within the structure is closely related to its thermo–mechanical properties and device reliability. However, thermal resistance is limited in describing the temperature distribution. Finite element analysis (FEA) requires time-consuming construction of 3D models. Therefore, to depict the temperature distribution of FOPLP rapidly and accurately, a numerical heat transfer model was proposed for the double-sided package structure. The solution was obtained from the steady-state thermal balance Laplace equation using the separation of variables method. Several boundaries were analyzed to determine the specific parameters in the model. Finally, the temperature field predicted by the derived numerical model was compared with finite element simulation results. The proposed model was consistent with both Silicon (Si) and Silicon Carbide (SiC) FOPLP structures within the error of 15 % at the center of the device, which verified the validity and accuracy of the numerical model for double-sided heat dissipation. The proposed models and results could contribute to the development of effective thermal design tools for double-sided thermal power modules.

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The creation and evolution of the Songliao Block, Northeast China, is believed to be related to the closure of the Paleo-Asian and Mongol-Okhotsk oceans, and to the subduction of the Paleo-Pacific Ocean. Geochemical and geophysical data indicate a complex tectonic history that may have left signatures of the superposition of separate tectonic events. However, the relationship between the current lithospheric structure of the Songliao Block and those tectonic events is not clear. In order to shed light on this question, a three-dimensional electrical resistivity model of the crust and mantle was generated from 138 magnetotelluric sites. The results show a heterogenous lithosphere with anomalous low-resistivity zones (∼10 Ω·m). The position of upper-crustal features (<10 km) correlates with a network of fault systems and rift basins. Based on estimates of high crustal temperatures, mid-lower crustal features (15–35 km), some of which appear near seismic reflectors, are attributed to partial melts (∼5%) containing moderate-high water contents (4.5 wt. %). A deep (>45 km) feature is interpreted as an asthenospheric upwelling near the center of the Songliao Block, where seismic evidence indicates a thin lithosphere. It is proposed that the collision, convergence, and suturing of blocks caused by the closure of the Paleo-Asian Ocean and the bidirectional convergence between the Mongol-Okhotsk and Paleo-Pacific Ocean may have produced weak tectonic zones throughout the lithosphere. They provided a structural basis for the later upward movement of fluids and melt, likely due to hydrous upwellings caused by the subduction of the Paleo-Pacific system.@en