@article{sinha_zaghari_ryu_hopkins_2024, title={A 400W, 250kHz (2kW Peak) Integrated GaN Half Bridge Power Module in a Non-Isolated Buck Converter}, ISSN={["1048-2334"]}, DOI={10.1109/APEC48139.2024.10509081}, abstractNote={This work demonstrates the design, fabrication, and electro-mechanical performance of a 60V/400W/250kHz Buck Topology-based GaN Half Bridge power module using high thermal conductivity thin organic substrates. The module integrates GaN power devices, gate driver, bypass capacitor, bootstrap capacitor, diode, resistor, and power decoupling capacitors into a power-dense package for increased performance. Thermally the module produces 97% efficiency under hard switching with forced air cooling. ANSYS Q3D parasitic extraction revealed a 2.7nH DC power loop inductance and 2.5nH at the switching frequency (250kHz). A Double Pulse Test (DPT) verified high switching speed performance at an instantaneous 2kW, i.e., five times than rated steady state buck operation. Finally, an FEA-based thermo-mechanical analysis was carried out to predict the package's stress distribution and mechanical reliability.}, journal={2024 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Sinha, Sourish S. and Zaghari, Pouria and Ryu, Jong E. and Hopkins, Douglas C.}, year={2024}, pages={168–174} }
 @article{shin_ahn_mun_lee_zaghari_park_park_ryu_jang_2024, title={Deep Neural Network-Based Temperature Mapping Technique for Heat Sink on Electronic Devices Using Local Thermocouple Sensors}, volume={38}, ISSN={["1087-6545"]}, url={http://dx.doi.org/10.1080/08839514.2024.2389374}, DOI={10.1080/08839514.2024.2389374}, abstractNote={Heat generated by electronic devices can lead to thermal deformation, damage, and fatigue failure, underscoring the importance of monitoring heat distribution. This study introduces an artificial neural network using two thermocouples for cost-effective temperature distribution prediction. Experimental data from heated systems on chip with attached heat sinks were used for training and validation, integrating thermocouple measurements and infrared camera data. The method's applicability was verified across four different heat sinks. Additionally, finite element analysis compared stress and strain based on predicted and actual temperature distributions, addressing conventional limitations that focus solely on temperature validation. Furthermore, the temperature of any coordinate could be output by including the coordinate as an input of neural networks, eliminating the hassle of re-constructing or learning the DNN to obtain the temperature of the desired coordinate. Results showed that the temperature distribution could be predicted with high accuracy (over 0.95), and the maximum error rate for stress and strain predictions was 7% in the worst case. This confirmed the feasibility of artificial neural networks to predict the temperature distribution using a minimal number of sensors and ensure robust performance even if the heat sink changes.}, number={1}, journal={APPLIED ARTIFICIAL INTELLIGENCE}, author={Shin, Jaehee and Ahn, Hyun and Mun, Gwang-Hyeon and Lee, Jeongmin and Zaghari, Pouria and Park, Young-Min and Park, Jinhyoung and Ryu, Jong Eun and Jang, Dong-Won}, year={2024}, month={Dec} }
 @article{phillips_zaghari_ryu_zikry_2024, title={Microstructural behavior of CNT-PDMS thin-films for multifunctional systems}, volume={187}, ISSN={["1878-5840"]}, url={https://doi.org/10.1016/j.compositesa.2024.108473}, DOI={10.1016/j.compositesa.2024.108473}, journal={COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING}, author={Phillips, Matthew and Zaghari, Pouria and Ryu, Jong Eun and Zikry, Mohammed}, year={2024}, month={Dec} }
 @article{al shibli_chaturvedi_kanagaraj_zaghari_choi_ryu_2024, title={Sol-gel fabricated one-dimensional LiFePO<sub>4</sub> microstructures for carbon nanotube-based nanocomposite freestanding sheet as cathode material for Li ion batteries}, volume={1}, ISSN={["1530-793X"]}, url={https://doi.org/10.1177/00219983231225703}, DOI={10.1177/00219983231225703}, abstractNote={ Lithium Iron Phosphate (LiFePO4) microstructures have been synthesized using the sol-gel process. One-dimensional (1D) LiFePO4 microstructures were fabricated using tissue paper as a template under different temperatures to form pure phase microstructures. XRD analysis confirmed the single phase nature of orthorhombic olivine-structured LiFePO4 with Pnma space group. SEM analysis authenticated the formation of 1D LiFePO4 microstructures along with some clusters of particles. LiFePO4-multi-walled carbon nanotubes (MWCNT) freestanding sheets were prepared using a tape-casting process. Further, the electrochemical properties of LiFePO4-MWCNT freestanding sheet were analyzed through electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge analysis. }, journal={JOURNAL OF COMPOSITE MATERIALS}, author={Al Shibli, Hamda and Chaturvedi, Prerna and Kanagaraj, Amarsingh Bhabu and Zaghari, Pouria and Choi, Daniel S. and Ryu, Jong Eun}, year={2024}, month={Jan} }
 @inproceedings{zaghari_sinha_ryu_franzon_hopkins_2023, title={Finite Element Analysis and Fatigue Life Prediction of a Laterally Conducting GaN-Based Power Package Under Thermal Cycling}, volume={Volume 12: Micro- and Nano-Systems Engineering and Packaging}, url={http://dx.doi.org/10.1115/imece2023-111682}, DOI={10.1115/imece2023-111682}, abstractNote={Abstract Thermal fatigue life analysis of GaN packages is an important consideration that affects the reliability and durability of electronic devices. In this paper, the fatigue life assessment of a GaN laterally conducting power packaging, including SAC305 and Sn63/Pb37 solders was conducted using the finite element analysis (FEA) method. The thermal cycling loading was chosen based on JEDEC Standard JESD22-A104D condition M. With temperature cycling from −40°C to 150°C. To simulate the viscoplastic behavior of solder materials under thermal cycling, the Anand constitutive model was adopted. Coffin-Manson, Engelmaier, and Solomon empirical models were utilized to predict the cyclic life of the package based on stress and strain distribution in the solder layers. Results showed that the critical solder joint location of the failure was in the SAC305 solder. The maximum inelastic strain range of SAC305 solder was calculated to be 0.023697. The fatigue life prediction of the module showed that the Engelmaier model was the most conservative model resulting in a fatigue life of 136 cycles.}, booktitle={Volume 12: Micro- and Nano-Systems Engineering and Packaging}, author={Zaghari, Pouria and Sinha, Sourish S. and Ryu, Jong Eun and Franzon, Paul D. and Hopkins, Douglas C.}, year={2023}, month={Oct}, pages={V012T13A021} }
 @inproceedings{zaghari_sinha_ryu_franzon_hopkins_2023, title={Thermal Cycling and Fatigue Life Analysis of a Laterally Conducting GaN-based Power Package}, ISSN={["2164-0157"]}, url={http://dx.doi.org/10.1109/3dic57175.2023.10154901}, DOI={10.1109/3DIC57175.2023.10154901}, abstractNote={Thermal reliability is a critical factor in ensuring the performance and efficiency of GaN-based electronic devices. In this paper, the fatigue life assessment of a laterally conducting GaN power package that uses a two-solder hierarchy of SAC305 and Sn63/Pb37 on a 120μm thick dielectric for device attach was conducted using an FEA. The double-sided package structure also introduced thick Cu as integrated baseplate layers for mechanical mounting into higher packaging levels while providing surfaces for double-sided cooling. The internal structure varied spacer thicknesses for planarization and inclusion of package-integrated decoupling capacitors. The solder materials were simulated by using the Anand viscoplastic constitutive model. Coffin-Manson, Engelmaier, and Solomon empirical strain-based models were utilized to predict the cyclic life of the package. Based on the results, the critical solder joint location was predicted in the Sn63/Pb37 solder layer between the GaN and Cu spacer, with a strain range of 0.02797. The worst-case life prediction for the module was 150 cycles using the Coffin-Manson model.}, booktitle={2023 IEEE International 3D Systems Integration Conference (3DIC)}, publisher={IEEE}, author={Zaghari, Pouria and Sinha, Sourish S. and Ryu, Jong Eun and Franzon, Paul D. and Hopkins, Douglas C.}, year={2023}, month={May} }
 @article{hosseinalipour_zaghari_2022, title={Design and fabrication of catalytic infrared fruit dryer to evaluate its performance in the bananas drying process}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85128922328&partnerID=MN8TOARS}, DOI={10.1111/jfpp.16627}, abstractNote={The present research was aimed to investigate the effects of utilizing catalytic infrared (CIR) heaters and their combination with convective heat transfer (Combined method) on the drying characteristics of bananas. The CIR and combined drying of 5 mm $$ 5\ \mathrm{mm} $$ samples were conducted at various temperatures (60, 70, and 80°C). The drying kinetics, mathematical modeling, and color change in samples were investigated. The results showed that the combined method would prolong the drying process compared to the CIR drying up to 31%. Among the seven investigated thin-layer drying models, the two-term model showed the best accuracy with R 2 $$ {R}^2 $$ ranging between 0.984 and 0.998. The results showed that the drying rate had a decreasing trend by a decrease in moisture content and temperature. The color change in samples ( ∆ E $$ \Delta E $$ ) was observed in the range 15.18–33.61. The study of sample colors indicated at 70 and 80°C, the combined method could result in minor change. Practical applications Due to multiple advantages such as significant durability, ease of transportation and storage, and providing essential nutrients, dried fruits have attracted much attention over the years. This study investigates the Catalytic IR method and the combined CIR and hot air method in the drying process of bananas. According to the results, utilization of the CIR method of drying results in a significant drying time compared to conventional methods such as hot air or solar drying. Moreover, the advantages of the CIR emitters, such as lower fuel consumption and reduced emitted pollutants such as CO and NOx, could be considered a great potential to supersede the conventional drying methods. The outcomes of this study can be used to predict the drying kinetics of bananas and to opt for the best drying conditions to achieve the most desirable color quality.}, journal={Journal of Food Processing and Preservation}, author={Hosseinalipour, S.M. and Zaghari, P.}, year={2022} }