Papers by Keyword: Electrical Stress

Abstract: This paper presents electrical stress analysis from capacitor bank switching in a 115 kV substation. The actual data of all equipment in substation are used in the simulated circuit by using ATP/EMTP program. The cases study focused on the determination of proper value of series reactor, effect of circuit breaker pole discrepancy on inrush current, line model selection and load variation. Electrical stress from energizing inrush current as well as transient recovery voltage and rate of rise of recovery voltage imposed on power circuit breaker during capacitor bank has been analyzed. The obtained results are used as guidelines for analysis of the electric stresses on substation equipment while capacitor banks are energized. Moreover, those results can be used to select the proper rating of circuit breakers to withstand the electric stresses in the transmission network.

Abstract: Heat flux inside the HP LED chip is also increasing with the increasing drive current, integration and miniaturization of LED chips. The junction temperature of LED strongly depended on the heat transmission capacity of die attach layer, which provided the heat dissipation channel between the heat generating LED chips and the heat slug. The voids, interrmetallic compounds or a small delamination would lead to the increasing thermal resistance in the die attach layer. In this paper, the reliability of soldered-bonded interfaces was studied in high-brightness LEDs, which were prepared by Cree and currently available on the market. Results revealed that the higher drive currents would lead to the accelerated degradation or failure of treated LEDs. Additionally, the injection current had an important effect on void formation and growth at the solder-bonded interfaces. The larger drive current would induce the delamination between LED die and heat slug. This study provided some guidance for the end users and a theoretical basis for solder-bonded technologies.

Abstract: Heterojunction bipolar transistors (HBTs) are playing an important role in microwave and power applications. When HBTs operated at high power, the power dissipation and self-heating effects will enable the generation of electrical properties in the transistor failure. The failure experiment system of microwave power HBTs was established. Based on this system, the changes of electrical parameters of HBTs in deferent stress, such as Gummel plots, base current various different base-emitter voltage and base-collector voltage, were measured and analyzed. At the same time, the failure of base current of SiGe HBTs under the condition of FC, SC and thermal stress are studied respectively. It was found that ΔI_B is the sensitive parameter of electrical and thermal stress. Based on this reason, we presented the failure model of I_B. This model could explain the experiment phenomenon successfully, which is very important and useful for applications of microwave power analog IC’s.

Abstract: The influence of stacking fault (SF) generation on the reverse blocking characteristics has been investigated on SiC 10 kV, 5 A Merged PiN (MPS) diodes. For the first time, we have observed that the generation of SFs under forward biased stress increases the reverse leakage current. In addition, the presence of a secondary diode formed by the electrical stress was observed and attributed to the breakdown voltage failure on certain devices.