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The Packaging Technologies for GaN HEMTs
Published in Hongyu Yu, Tianli Duan, Gallium Nitride Power Devices, 2017
In conventional power electronics, three-lead packages, like TO-220, are commonly used for packaging discrete power transistors. As for power integrated circuit (IC) applications, PQFN packages are mostly available. However, these conventional packages cannot take advantages of GaN HEMTs. Therefore, some enhanced packages like DirectFET and Land Grid Array (LGA) are adopted. DirectFET is a packaging technology created by International Rectifier. Nowadays, this technology is used to package the GaN radio frequency (RF) power transistors, and the packaged products have been introduced to some base station manufactures. These devices with larger bandwidths, higher power density, and higher efficiency could pave the path to 5G technology. Another major corporation in the GaN power field, Efficient Power Conversion (EPC), is pushing its LGA packages for GaN HEMTs. By adopting this method, EPC has launched its fourth-generation commercial products, Gen4 eGaN® FETs, ranging from 30 V to 200 V [30].
Layout, Grounding, and Cooling
Published in Douglas Self, Audio Power Amplifier Design, 2013
Many standard shapes are available for common semiconductor packages. For a TO-220 package and a mounting pressure of 50 psi, thermal resistance ranges from 1.5 to 3.4°C per Watt. Some of the bulk thermal conductivities for the Warth/Laird materials are included at the bottom of Table 25.5, and it can be seen that there is quite a difference between the standard K177 and the high-performance K381. You can also see that even the best thermal washer materials have much less thermal conductivity than the worst of metals, and this is why thermal washers have to be so very thin.
Effect of pin geometry on material flow characteristics of friction stir welded dissimilar AA6061/AA2014 alloys
Published in Australian Journal of Mechanical Engineering, 2022
R. Venkateswara Rao, M. Senthil Kumar
Ductility of the weld samples was studied by conducting the flexural test. Test specimen profile is cut from weldment as per ASTM E190 standard. Generally FS is more than YS which referred in (Rao, Reddy, and Rao 2015), the experimental results noted that the maximum UTS measured 191MPa, whereas minimum FS reported as 220 MPa, which is supported with above reference. The results reveal that fracture strength of all the welds are more than YS of AA 6061 base alloy, it showed an improvement of 102–122%, but FS values are less than UTS of similar alloy in the range of 81–97%. Flexural stress increases with increasing the tool rotational speed between 710 and 900 rpm, after that it decreases from 1120 rpm onwards. The welds processed at 710 rpm (S1–S9) show min and max FS values as 220 MPa (81%) and 249 MPa (92%) respectively. At higher tool rotational speeds at 900 rpm (S10–S18) FS values are increased as 239 (88%), 263 MPa (97%) as compared to UTS of base AA6061 alloy. The subsequent welds processed with 1120 rpm (S19–S27) showed the lower FS 236 MPa (87%), 256 MPa (94%) as compared to UTS of base AA6061 alloys. Finally the maximum flexural strength recorded 262 MPa of the sample 11 processed at 900 rpm, with a feed of 20 mm/min using a hybrid square pin profile shown in Figure 20.
Exergy analysis of a novel low-heat recovery organic Rankine cycle (ORC) for combined cooling and power generation
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Fidelis I. Abam, Tobinson A. Briggs, Ekwe B. Ekwe, C. G. Kanu, Samuel O. Effiom, M. C. Ndukwu, S. O. Ohunakin, M. I. Ofem
Additionally, to improve the performance of ORCs, the cycle has undergone modifications from the generic cycle to ORC with an internal heat exchanger, ORC with turbine bleeding and ORC with turbine bleeding and regeneration (Dai, Wand and Gao 2009; Roy, Mishra, and Misra 2010). In all this technical improvement, the ORC has continued to have some marginal improvement from the generic cycle. To further improve the performance of the ORCs many researchers have carried out designs, modeling and optimization of ORC, either at hybrid form or non-hybrid form. For example, Wenqiang, Xiaoyu, and Yanhui (2017) evaluated the efficiency of a combined cycle ORC with an absorption refrigeration system (ARC). The results obtained show that the ARC cannot couple well with ORC section at waste heat temperature greater than 220℃ or lower than 140℃. However, the combined ORC and ARC maintained a higher exergy efficiency than the generic system.
Compact instrumentation and (analytical) performance evaluation for laser-induced breakdown spectroscopy
Published in Instrumentation Science & Technology, 2019
Guangmeng Guo, Guanghui Niu, Qingyu Lin, Shuai Wang, Di Tian, Yixiang Duan
Overall seven unites were integrated into the unified system, including a power module, an optical device module, a spectrometer, a laser source, a control module, a sample stage, and a client software. The function of each unit is described as follows: The power module converts the input 220 VAC to the operating voltage for the control module and for the laser source, respectively. The optic devices module is utilized for focusing the laser pulse beam onto sample surface, obtaining the real-time image of the sample, and transferring the light signal of plasma to electric pulse. The spectrometer is a device for the acquisition of plasma spectrum information. The laser source is used to be focused onto the sample surface and generate laser induced plasma. The control module is regarded as an intermediate device for interaction between client software and the instrument, and it also achieves the functions of conducting the emission of the laser source and making a delay time for the electric pulse to trigger the spectrograph for spectral acquisition. The sample stage makes sure that focus of laser beam is accommodative in terms of different conditions. The client software serves as an interactive interface to give guidance on measurement, such as setting the parameters of laser and spectrometer, displaying the real-time image of sample surface, receiving and operating the spectral data of the plasma.