Effect of Ag on the Co-firing Behaviour of Ferrite and LTCC
Date Issued
2010
Date
2010
Author(s)
Lee, Yueh-Han
Abstract
The co-firing behaviour of NiCuZn-ferrite, LTCC and Ag has been investigated in the present study. In order to investigate the effect of each component during co-firing, the glass powder and Al2O3 powder were mixed with ferrite powder and sintered. Then, ferrite powder, LTCC powder and Ag powder were mixed with each other and co-fired. The interactions between Ag and ferrite/LTCC are observed. Several model laminated specimens composing of ferrite, LTCC and Ag layers are also prepared. After co-firing, the interaction and diffusion between each layer are investigated. The microstructure is observed by scanning electron microscopy (SEM). X-ray diffraction (XRD) is used for phase identification. The magnetic properties of the samples are measured by superconducting quantum interference device magnetometer (SQUID) and impedance analyzer. The diffusion is investigated by electron probe micro-analyzer (EPMA). As co-firing Al2O3 with ferrite, Fe3+ ions are substituted by Al3+ ions and the reactant, α-Fe2O3, is formed. Such reaction induces a degradation of magnetic properties. The ions in glass phase also diffuse into ferrite during co-firing, but the extent of reaction is lower comparing to that during co-firing of ferrite and Al2O3. Such ion exchange changes the composition of glass, and induces the precipitation of a second phase. While co-firing of ferrite, glass and Al2O3, theα-Fe2O3 and anorthite phases are also found. The magnetic properties of ferrite are degraded further. The chemical interaction is not found as co-firing Ag with ferrite/LTCC, but a large number of Ag diffuses into glass phase of LTCC during co-firing. Such reaction should be an ion exchange reaction, which change the composition of LTCC. In the laminated specimens, because of the interaction between ferrite and LTCC, the diffusion of Ag into LTCC is possible. Therefore, a larger amount of second phase is precipitated and some may contact the Ag electrode.
Subjects
NiCuZn-ferrite
LTCC
silver diffusion
laminated specimen
ion exchange
Type
thesis
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