| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 101 === The present study aims to investigate the co-firing behavior between dielectric and ferrite. The present study is divided into two parts. In the first part, a series of powder mixtures composing of low-temperature-fired dielectric and NiZn ferrite have been prepared. The reactions between the dielectric and ferrite during co-firing are investigated. In the second part, dielectric layer, ferrite layer and Ag electrode, were laminated together to form various patterns. The diffusion behavior between the dielectric and ferrite is studied.
For the first part, the composites can be densified below 950℃except the specimen containing 90% ferrite. The addition of dielectric inhibits the grain growth of ferrite. The resonance frequency increases with the increase of ferrite content; while the dielectric constant decreases at the same time. A larger permeability μ’ is observed with increasing NiZn ferrite content. The Maxwell-Garnett mixing rule was used to describe the magnetism of the composites, assuming dielectric or NiZn ferrite as matrices. The measured results were closer to the values calculated by using dielectric as matrix.
For laminated specimens, two groups of specimens were prepared. The delamination was observed in some laminates. It may due to the difference in the sintering shrinkage and thermal expansion. The diffusion distance increases with the increase of co-firing temperature. The diffusion behavior is also affected by the design of Ag pattern. The inter-diffusion between ferrite and dielectric is taken place during co-firing. The Fe, Cu, Ni, Zn (from ferrite) diffuse to dielectric layer and the Ti and Nd (from dielectric) diffuse to ferrite layer. A new layer is formed between Ag layer and dielectric layer as the laminate was fired at 950℃.
|
|---|
