叠层片式电感器过载电流下热应力对开路的影响

Influence of thermal stress on the open circuit of multilayer chip inductor(MLCI) under overload current

为了降低叠层片式电感器(MLCI)在过载电流下的开路失效几率,提高MLCI的可靠性,研究了MLCI过载电流条件下热应力对内电极开路的影响。将同等型号的MLCI样品分为三组,分别放置于-55℃、25℃、120℃三种不同温度的环境中,通过调节电流,使得内电极电阻都达到0.57Ω且能够稳定5 min,电阻与温度的关系表明内电极温度相同,环境温度不同,热应力不同。保持加载电流的大小,直到电感器发生开路。实验结果显示:低温环境中的MLCI比高温环境中开路时间短,是因为MLCI粗细不均匀的内电极在热应力的作用下,电极较细部位发生形变,致使电阻增大,焦耳热增多,温度升高,温度达到熔点后,电极开路。

In order to reduce the failure rate of open circuit of multilayer chip inductor(MLCI)under overload current and improve the reliability of MLCI,we investigated the influence of thermal stress on the open circuit property of the inner electrode under the overload current condition.The MLCIs were divided into three groups,which were placed in–55℃,25℃and 120℃environment.The resistance of inner electrodes in the three groups of MLCIs reached 0.57Ωand kept for 5 minutes via adjusting the injected current.The relationship of the resistance value and the temperature indicates that the inner electrode suffered from varies thermal stress under same inner electrode temperature and different environment temperature.Keep the injection current till the inductor opens.The results show that the open time of MLCI in low environment temperature is shorter than the one in high environment temperature.The difference of open circuit time in different environment results from the thick and thin irregularity of the MLCI inner electrodes under thermal stress condition.The thinner part of the inner electrode was easier to be deformed and suffered from higher resistance value and increased joule heat.Eventually,the temperature of the inner electrode was heated up to the melting point of electrode and further caused the open circuit of MLCI.