In pursuit of developing a low-inductance power module, we engineered a module featuring a POL double-layer facing structure. This design demonstrated a mutual inductance cancellation effect of 14.9nH, reducing the module's parasitic inductance to 8.7nH. Furthermore, by decreasing the inter-module distance to 1.0mm in the simulation, the mutual inductance cancellation effect was enhanced, resulting in a reduction of the module's parasitic inductance to 5.5nH.
Commercial solder alloys with the addition of bismuth (Bi) have gained prominence in the electronics manufacturing industry, because of their low melting point and the strengthening effect associated with Bi. If the Bi concentration exceeds the solubility of Bi in Sn at room temperature (approximately 1.7 wt” in typical Sn-based solder alloys), there will be a driving force for precipitation of Bi within the Sn phase. However, the solubility of Bi in Sn is strongly temperature dependent and dissolution of some or all of the Bi precipitates may occur at higher temperatures, depending on the alloy composition. To study the thermal stability in solders with different Bi content, two samples: Sn-3.SAg-3Bi-2Sb-O.8Cu and Sn-l.SBi-O.7Cu-O.OSNi (in wt.%) were characterised by in-situ scanning electron microscopy (SEM) and in-situ powder x-ray diffraction (PXRD). Bi dissolution was observed in the sample with higher Bi addition upon heating and pores remained when the sample was cooled down. On the contrary, in the sample with lower Bi concentration the microstructure remained identical before and after heating, indicating better thermal stability. Furthermore, the microstructure change caused by Bi dissolution is reflected in a volume expansion in the Sn phase lattice obtained by PXRD data.
With the increasing popularity of hybrid vehicles (HVs) and electric vehicles (EVs), the time required for their mass scrapping is also increasing. Therefore, attempts have been made to use storage batteries acquired from scrapped vehicles as fixed storage batteries; however, these batteries have not been widely used because of their lack of versatility and poor cost-effectiveness. In this study, we developed a versatile control program and hardware to use all vehicle-mounted storage batteries as stationary storage batteries regardless of the vehicle type, using the entire vehicle-mounted storage battery and parts. As a result, we realized batteries with a more stable system whose selling price was lower than that of new batteries. Moreover, attempts are in progress to develop a high-performance energy storage system that is not possible using fixed batteries by developing a system that integrates high-power (e.g., in HVs) and standard-power (e.g., in EVs) storage batteries. To use vehicle-mounted storage batteries from HVs and other vehicles as fixed storage batteries, we analyzed their charge/discharge control signal data to construct a basic algorithm for the control program, and we further succeeded in developing an original hardware design for incorporating the storage batteries into the system.
The objective of this study is to evaluate how boiling heat transfer performance changes when inhibitor EDTA that we developed as scale inhibition technology is added to LLC (Long Life Coolant) for cooling automotive inverters. The boiling heat transfer performance of water, water+antioxidant, LLC@30vol % , LLC@30vol % +antioxidant, and LLC@30vol % +EDTA are investigated in the order. Since the Pr number of the LLC@30vil % is much higher than that of water, so that the heat transfer performance of LLC30vol% with/without the antioxidant, including the boiling heat transfer performance, decreases compared with water. However, adding the inhibitor EDTA to LLC makes the heat transfer performance to recover and overcome the performance of LLC30vol % with/without the antioxidant.
A novel planar solder geometry is described that allowed real-time. non-destructive monitoring of the rate of bismuth segregation at the anode in eutectic Sn-Bi solder joints of lengths in the range 180-450 µm at various current densities and temperatures while tracking the extent of electromigration by electrical resistance means. The rate of bismuth segregation was found to be somewhat proportional to the solder joint length indicating a probable Blech back-stress effect. Initially, the solder joint electrical resistance decreased followed by an increase. The period of decreasing electrical resistance was much less at higher current densities. The electromigration activation energy was determined to be 0.92 eV.
Exploiting the growth rate dependency of intermetallic compounds (IMCs) on the substrate composition, the possibility of controlling porosity during transient liquid phase (TLP) bonding via a composition gradient is investigated. A Cu substrate with a variable Ni concentration was prepared through selective electroplating and subsequent heat treatment. When this substrate reacted with a molten Sn-rich alloy, there was a non-uniform growth of the Cu 6 Sn 5 IMC. It is proposed that by tailoring the direction of the composition gradient in the substrate, the IMC growth rate can be controlled in such a way as to progressively move the solid-liquid front to redistribute any porosity away from the central region of the joint and thereby improve reliability.
The common-mode antenna (CMA) model and the equivalent differential-mode (DM) circuit are based on the imbalance difference theory. The theory describes the mode conversion between the common mode (CM) and differential mode (DM) by focusing on the imbalance difference. The CMA model has been proven to provide excellent estimations of CM radiated emission. In this work, the CMA model is combined with the equivalent DM circuit to extend the CMA model to practical applications that include the mode conversion in both DM to CM and CM to DM directions and radiation loss. The combined model is applied to cable-connected printed circuit boards (PCBs) with an adjacent metal chassis that imitates a signal transmission system placed close to the metal chassis. The combined model calculated the CM radiated emission using a field-and-circuit co-simulator, considering the mode conversion in both directions and the radiation loss. Simulation results confirmed that the combined model precisely estimated the CM radiated emission by being separated from the DM radiated emission. The combined model also provided physical insights into EMC design that will enable the CM radiated emission to be efficiently reduced.
