Lateral growth of coating on Co2Z ferrite during electroplating of multilayer chip inductors

Lateral growth of nickel coating on a ferrite substrate during electroplating of multilayer chip inductors (MLCI) was investigated. It was found that the lateral growth occurred after a certain time of electroplating, but not at the initial stage. Resistivity of the ferrite and inductance of MLCI decreased continuously with electroplating time. Moreover, surface morphology of the ferrite changed significantly after electroplating, which indicated chemical reactions to take place during the plating process whereas corrosion effect of acid solution on the material can be neglected. Judging from the results obtained, it was inferred that the resistance degradation should be attributed to hydrogen reduction during electroplating, which consequently led to the lateral growth of on the ferrite.