Laminated Chip Inductor Open Circuit, Short Circuit Failure Mode

In recent years, there has been a developing trend that electronic devices shouldbe of super-small, lightweight and high-performanable. Therefore, more and moreattention has been paid to the high-density surface mount technologies (SMT), amongwhich the multi-layer chip inductor (MLCI) is one of the most important three majorpassive components in the surface mount circuits.MLCI is mainly applied to the electronic circuits or the systems, and thebreakdown of which is usually due to the “open-circuit” or “short-circuit” effects. Inthis thesis, by investigating the failure mode and the related mechanism of“open-circuit” or “short-circuit” in MLCIs, we could carry out some modificatiosduring the design and implementation processes of the MLCIs, which can effectivelyreduce the rate of the open-circuit and short-circuit and protect the electronic circuitsor systems from the damage of the component failure.In this thesis, the reasons that lead to the failure of the open-circuit andshort-circuit in MLCIs are analyzed. And on this basis, the modification suggestions inrelation to the product design and manufacturing processes are put forward, whichfinally help to optimize the quality of the MLICs. The main contents of the paper are asfollows.1) The paper analyses and studies the influence of the design and productionprocess in the multi-layer chip inductor (MLCIs) on the open-circuit failure. Duringthe design stage, the coincidence degree of contrapuntal connection, which are amongthe inner conductor layers and among the connection points, are the main parameters inthe inductor production, therefore they should be paid to high attention. During theproduction stage, the environmental humidity, the mold printing quality, thecontrapuntal connection range and the matching co-firing, etc. are the key processes inthe production of the MLCIs. Based on a quantity of contrast test, a key point thatresults in open-circuit failure is found out, and then some improvement measures areproposed.2) The paper systematically studies the influence of the cast membrane, the forming process and the end coating on the short-circuit failure of MLCIs. The kindsand the uniformity of the slurries, the particle size and its distribution characteristics ofthe raw powder, all have an important effect on the short-circuit failure of the devices.The paper specially focuses on the key technical specifications and the defects, such asthe thickness of the inner-conductor silver layer and the dielectric film, voids andbubbles which are caused by casting. Furthermore, the reasons and the relatedmechanisms of the failure are emphatically analyzed and discussed. In the end, bycombining with processing experiments, some preventive actions are put forward.