Functional degradation of NiZnCu-based multilayer chip inductors during nickel electroplating

Abstract

Functional degradation of NiZnCu-based multilayer chip inductors (MLCI) during nickel electroplating and subsequent lateral growth of metal coating on the ferrite substrate were studied. It was found that the resistivity of the NiZnCu ferrite and inductance of MLCI decreased continuously during the electroplating. Scanning electron microscopy (SEM) analysis showed that the surface morphology of the ferrite had changed significantly after the electroplating. However, the resistance-degraded specimens can be restored partially through air annealing at elevated temperature. Based on the results obtained, it was inferred that the ceramics surface had suffered hydrogen reduction during the electroplating, which led to the functional degradation of ferrite material and the lateral growth of nickel coating.